OF THE NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 1949/67531/metadc60233/m... · CONTENTS .,. Page Letterof Transmittal. . . . . . . . . . . . . . . . . . . . . . . . . . . .

THIRTY=FIFI’H ANNUAL REPORT

OF THE

NATIONAL ADVISORY COMMITTEE

FOR AERONAUTICS

1949

INCLUDING TECHNICAL REPORTS

NOS. 922 to 950

UNITEDSTATE3

GOVER.N__T PFCJXTJXGOFFICEWMHINGTON : 1951

Fm de bytheSnmIntendentofDocmnentqU.S. OowrmnentPrintincO&q W6sh!ngtom2 D. C. - - - Prise $S50(Bnckram)

CONTENTS .,.Page

Letter of Transmittal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vLetter of%bmittal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VIIThirty-fif thAnnualRepor t...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1PART I. TECHNICAL ACTWITIES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

RESEARCE ORGANIZATION AND PROCEDURES. . . . . . . . . . 3AERODYNAmC RESEARCH . . . . . . . . . . . . . . . . . . . . . . . . . . . 5PROPULSION RESEARQt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

AIRFRAME CONSTRUCTION RESEARCH. . . . . . . . . . . . . . . . 36OIWRATING PBOBLEMS RESEARCH. . . . . . . . . . . . . . . . . . . . 45

PAETII. COMWITEEORGANIZATION. . . . . . . . . . . . . . . . . . . . . . . . . 57PART III. F’INANCIAL REPORT.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62TECHNICAL REPORTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

11

TECHNICAL REPORTS

No.

922. CharacterMicsofLow-.kWCct-RatioWingsat Super-critical Mach Numbem. By Johu Stack and W.F.Lindsey, NACA ------------------------------

W23. Effect of .ifterbociy Length and Keel Angieon Mini-mum Depth of Step for Landing StabiIity and onTake-Off StabiIity of a Fl}ing Boat. By RoIandE. Olsonand Norman S. Land, NACM----------

g24. Application of Theodor.wn’s Theory to PropelIerDesign. By John L. CrigIer, NAC.A___________

925. StabiIity Derivativ= at Supersonic Speeds of ThinRectangular Wings with Diagonals Ahead of TipI[ach Lines. By Sidney M. Harmon, NACA----

926. Sound-LeveI llewuements of a Light AirplaneModiEed to Reduce Noise Reaching the Ground.By .& W. Vogeley, NilCA- -------------------

927. Appreciation and Prediction of Flying QuaIities. ByWilliam H. PhiIIips, NAC.4--------------------

WM.Analysis of Performance of Jet Engine fmm Charac-teristics of Components. II—Interaction of CoU-pone])ts as Determined from Engine Operation.By Arthur W. GoIcMein,Sumner Alpert, WiiliamBeede, and Karl Kovach, NACA ---------------

929. Dislocation Theory of the Fatigue of Metafs ByE. S. MachIin, NACA------------------------

930. h Analytical Method of Estimating Turbine Per-formance. By Fred D. Kochendorfer and J. CaryXettIes, >-.lCA------------------------------

931. Correlation of CyIinder-Head Temperatures andCoo[ant Heat Rejections of a MuItic@nder,I.iquid-CooIed Engine of 1710-Cubic-Inch Dissplacement. By Bruce T. Lundin, John H.PovoIny, and Louis J. Chelko, NACA--- -------

932. Effect of ReynoMs N-umber in TurbuIent-FlomRange on FIame Speeds of Butwen Burner Flames.By Lawelf M. BoUingerand David T. ‘iWliams,NAC1---------------------------------------

W33. Performance of Conical Jet Nozzlesin Terms of F1OWand l’eIocity Coef6cients. By RaIph E. Grey,Jr., and H. Dean Wilsted, NACA-------.-__--_

934. Recommendations for NumericaI ScJution of Rein-forced-Panel and FuseIage-Ring ProbIems. ByX. J. Hoffand PauI A. Libby, Polytechnic Im=tituteof Bmoldyn----------------------------------

g35. Two-Dimensional Compressible FIow in Turbo-machines with Conic Flow Surfaces. By John D.Stanitz, NACA------------------------------

036. Design and Performance of FamiIy of DitTusingScrolls with Mised-Flow ImpeIIer and VanelessDiffuser. By W. B}-ron Bron-n and Guy R.Bradshaw, N.lC -----------------------------

Pwe

63

ml

S3

101

115

12L

167

1s3

193

207

231

239

305

A-o.

‘337.Constant-P~urc Combustion Charts InciudingEffects of Diluent Addition. By L. RichardTurner and DonaId Bogart., XACA------------_

93& Summary of Section Data on TrafIing-Edge High-Lift Devices. By Jones F. CahilI, !SACA-------

939. Theoret ioaI Characteristics in Supersonic FIOWofTwo Typea of Control Surfaces on TriangularWings. By Warren A. Tucker and Robert. L.Nelson, NAC4--------------------------------

W(I The D@gn of Low-Turbulence Wind TunneIs. ByHugh L. Drycfenand lra H. Abbott, NACA-----

941. Prediction of the Effects of Propeiler Operation onthe Static Longitudinal Stability of Singl&EngineTractor Monoplanes with Flaps Retracted ByJoseph Weil and WWam C. Sleeman, Jr., NACA-

942. Inwstigat ion in the Langley 19-Foot Preswre TuIl-neI of Two ‘il’iigs of NACA 65-210 and 64-210Airfoil Sectione with Various Type Flaps. ByJames C. SiveUsand Stanley H. Spooner, A’AC.4-

943. A Simplit7ed 31ethod for the Determination andAnalysis of the Neutral-LateraI-OscWt ory-Sta-bility Boundary. By Leonard Sternfield andOrdway B. Gates, Jr., NACA------------------

$)44.Heat Transfer to Bodies Traveling at High Speedin the Upper Atmosphere. By Jackson R. Staiderand David Jukoff, NACA---------------------

945. Two-Dimensional unsteady Lift Problems in Super-sonic FIight. By Max. .L Headet and HarvardLoma% NACA-------------------------------

946. PI@ic Buckling of a Rectangular Plate under EdgeThrusts. By G. H. HandeIman and W. Prager,Brown LTniversity----------------------------

947. The Development of Cambered AirfoilSections Hav-ing FavorabIe Lift Characteristics at SupercritictdMach Numbers. By Dowld J. Graham, NACA-

948. .ti Apparatus for Varying Effective DihedraI inFlight with Application to a Study of TolerableDihedral on a Con\-entionafFighter .tirplane. ByIf”fliam M. Kauffman; Charles J. LiddeU, Jr.;Man Smith; and Rudolph D. Van Dyke, Jr.;NACA--------------------------------------

949. Effect of Screens in Wide-angle DitTwws. By G. B.Sohubauer and W. G. Spangenberg, XationafBureau of S@&& --------------------------

950. Investigation of a Systematic Group of NACA 1-Series Codings With and Witbout. Spiunem. ByMark R. A’icholsand Arvid L. Keith, Jr., NACA-

111

Prigs

315

341

371

3s7

399

419

443

455

460

47g

507

529

545

5s5

Letter of Transmittal

To the Congrtw of theUnited States:In compliance with the provisions of the act of March 3, 1915, as

amended! establishing the NationaI Advisory Committee for &ro-mtutiq I transmit herewith the Thirty-fifth &mual Report of theCommittee co-rering the fiscal year 1949.

ELmm S. Tmmww.THE WI- HOUSE.

JANUARY16,1950.v

Letter of SubmittaI

~.lTION.iL bWSOEY (jomwrmm FOE AEION.\~~,

Wcuhington, D. C., December 16, l&f9.DE= MR. PRESIDENT:In con~pIiance with the act of Congress ap-

proved Narch 3, 1915, as amended (U. S. C. 1943, title 50, sec. 153),I have the honor to submit herewith the Thirty-fifth Aunual Reportof the Natiomd Advisory Committee for Aeronauti@ covering thefiscal year 1949.

Achievement of flight faster than the speed of sound by Americanresearch airplanes has gi-w.u a strong stimulus to the desi=mof veryhigh speed aircraft both in this country and abroad. The Committeehas evidence of increasing international competition in aeronauticalresearch and development. The stakes are high. Superior speed inmilitary aircraft is eesentiaI to the success of air attack m -wellas airdefense. In the age of atomic bombs it appears that no nation canwin a war without control of the air.

During the past year the Committee has directed much of its effortto solutions of the complex problems of high-speed flight. By theachie~ement of successful supersonic flight there -WRSgained forAmerica a substantial advantage in the race for air Leadership. This~min was made through the coordinated effort of scientists and en-gineers throughout the country-notably in the aircraft industry,the military establishment, and N’ACA—and supported by the workof educational institutions and other research agencies. The sameteamwork is required to consolickde these gains and to push for-ward. The Congress has wisely provided for increasing the effec-tiveness of the team by authoriz@ the Unitary Wind Tunnel P1anfor estabolishmentof needed facilities for tranwmic and supersonicresearch, development, and evaluation. The Unitary Plan repre-sents an extension of the teamwork idea initiated by the cooperativemilitary-industry-NACA research-airplane program that M toachievement of supersonic flight. In that program forces were joinedto produce research redts. In the Unitary Plan the same forceswill be joined to expedite the development and sound evacuation ofpracticaI aircraft capable of the superior performance required tomeet an emergency.. Respectfully submitted.

JEROMEC. HUNS.QChairman.

TEE PRESIDENT,The White Howe, Washington, D. C.

m

National Advisory Committee for Aeronautics

Headquurteiw,17S4 F StreetNW., Washington 96, D. C.

Created by act of Congress approved March 3, 1915, for the supervision and direction of the scientific studyof the probkms of flight (U. S.”Codej title 50, sec. 151). Its membership was increased from 12 to 15 by actapproved March 2, 1920, and to 17 by act approved May 25, 1948.. The members are appoin hxl by the President,and serve as such without compensation.

JEROMEC. HUNBAKER,Sc. D., Mssaachusette Institute of Technology, CMrrnun

ALEXANDERWETMORE,Sc. D., Secretary, Smithsonian Institution, T’iceChairman

HON.JOHNR. ALISOFT,Assistant Secretary of Commerce.DE~LEVW. BECO~K,PH.D., President, Johns Hopkins University.KARLT. CO~PTON,PH.D., Chairman, Research and Development

Board, Department of Defense.EDWARD U. CONDON,PH. D., Director, NationaI Bureau of

Stmdarde.JAMESH. DOOLITTLE,Sc. D., Vice President, Shell Union Oil

Corp.R. M. HAZEN,B. S., Director of Engineering, AIlison Di\tilon,

General Motors Corp.WILLIAMLrrTLEWOOD,M. E., Vice President, Engineering,

American Afrlinas, Inc.THEODOREC. LO~NQUEST,Rear Admiral, United States. Navy,

Deputy and Assistant Chief of the Burau of Aeronautic.

DONALD.L. PUTIT,Major General, Unit-cd StatesAir Form?Director of Research and Development, Officeof tho Chief ofStat7, Mat&iel.

JOHND. PRICE,Vice Admiral, United States Navy, Vice C!hicfofNaval Operations.

ARTHURE. RAYMOND,Sc. D., Vice President, Engineering,Dougl~ Aircraft Co., Inc.

FRANCISW.REXCHELDERF~R,Sc.D., Chief,United Stat- WeatherBureau.

HON.DELOSW. RENTZEL,Administrator of CivilAcronautiea,Departmentof Cogonerce.

HOYTS.VANDENBERG+,General,Chiefof Staff,UnitedSiatcaAirForce.

THEODOREP. WRIQHT,Sc. D., Vice President for Research,Cornell University.

HUGHL. DRYDEN,PH.“D., Direc~or—

JOEINF. VKWORY,LIJ. I)., .Ececutiue SccretarU

JOHNW. CRO”WLEY,JR., B. S., Amoakte Directorfor Re8earch E. H. CHA~BERL~~,fiecutive O@er

.-

HENRYJ, E. REID,D. Eng., Director, Langley Aeronautical Laboratory, Langley Fiel& Va.

SAIITHJ. DEFMCE, B. S., Director, Am= AeronautictiI Laboratory, Mof?fettField, Calif.

EDWARDR. SHARP,Sc. D;, Director, Lewis Flight propulsion Laboratory, Cleveland Airport, Cleveland, Ohio

TECHNICAL COMMITTEES

AERODYNAMICS OPERATINQPROBLEMSPO-iVERPLANTSFORAIRCRAFT INDUSTRYCONSULTINGAIRCRAFTCONSTRUCTION

Coordination of Reeearch Needs of Militarj and Cim”lAviation

preparation of Research Programs

Allocation of Probfems

Prevention of Dupkcafian

Considerattin oj Inuentione

.. ...+-..

IJAX~LEYAERONAUTICALLABORATORY, LEWS FLIOHTPROPULSIONLABORATORY, AXESAERONAUTICALLABOIZATOnY,Langley Field, Va. Cleveland Airport, CIevekmd, Ohio Moffett Field, Calif,

Conduct, unckr unijied control, for afl agencie8, of wientifi research on the fundamental prob.femaof jlight

OFFICEOF AERONAUTICALINTELLIGENCE,Wdington, D. C.

VIII

filf.ection, ctasei$cation, wrnpilation, and diaserninationof 8cien4i$cand technical information on aeronauhte

THIRTY-FIFTH ANNUALOF THE

NATIONAL ADVISORY COMMI!171!EE

V7.awmwrrox, D. (7., November 17,1949.

To the Qongrew of the United State8:

In accordance with the act of Congress, approvedMarch 3, 1915 (U. S. C. title 50, sec. 151), which estab-fi~hed the National Advisory committee for AWW-nautics? the Committee submits its thirty-fifth mnualreport for the fismtlyear 1949.

In the Committee’s report last year it was statedthat the tierican achievement of flight faster thanthe speed of sound by a special research airph+newouldinfluence our future concept of national security. Itwas pointed out that this accomplishment was actingas a stimulus to the design of very high-speed airpk.nesby removing concern relative to the existence of an un-known sonic barrier. During the past year the effectsof this stim.dus have become evident both here andabroad through supersonic fights by other experimen-tal airplanes.

The demonstrated possibility of supersonic flight isa significant turning point in aircraft performance.For the future, we must accept the view that flight atsupersonic speeds by practical military airplanes canbe attained by any nation wilLing to make the tiort.Another nation has apparently achie~ed succees in de-veloping an atomic eqhsion. It is logicaI to assumethat an intensire effort is being made to develop a meansfor transporting atomic weapons with as high a degreeof effectiveness as possible and at the same time to pro-vide defense against invading aircraft armed withatomic -weapons. Superior speed is generaIly ac-knowledged to be the most. important sirgle elementin successful air attack and in defense against such anattack Range also is important.. The attainment oflong range at supersonic speeds poses a most dficultproblem.

For America to continue its present supremacy inthe air till require that it de-relop military aircraftthat can fly faster than sound. This places emphasison research and development & in the case of theatomic bomb, America cannot expect to enjoy an exclu-sive ad~antage. At best it can only plan by vigorousand timely research to stay ahead of any potentialenemy in the development of aircraft of superior per-formance.

The Committee feels a sense of urgency in the con-duct of its broad comprehensive programs of scientficresearch in aeronautics, -which include the stimrdation

924i7a-51-2

REPORT

FOR AERONAUTICS

and coordination of basic research in scienti& andeducational institutions. There is no excuse for a com-placent attitude. We need to maintain technologicalsuperiority, in order that tve may have the most mod-ern aircraft as the backbone of American air power inb~g, on ~hatever basis it may be determined by theCongrees to be necersav to afford a reasonable degreeof security consistent -withthe national economy.

To e@ore more rapidly the little-known re@ons oftransonic and supersonic fight speeds, the cooperative .—industry-military-NACA research airplane project,which commenced with the USAF X-1 and Navy D-553airplanes, has grown to include more than a half-dozenairplane types. The scientfic information obtained todate from this flight program has given aeronauticsperhaps the greatest impetus in its history.

Notable during the past year has been the eagernessof aircraft designers to apply the new knowledge beiigobtained from the Committee’s high-speed research pro-gram. Now that experimental supersonic flight hasbeen attained, great efforts are bekg made by the AirFome and the Navy in fostering the design of opera- .-. ___tional transonic and supersonic aircraft. The Com-mittee notes with satisfaction a heaIthy pressure uponit from the military air servcies and from the air-craft industry for advanced scientfi data. This is thefit occasion in peacetime history that organized re-search effort has been unable to stockpile scientifickno-wkdge for future use. The demand is for advancedscientific knowkdge for immediate application.

ln the past &al year, the Cmnrnitteeplaced in opera-tion the third of its large sde supersonic wind tunnels.Each of thesetunnels is be~u used to study f undamentalaspects of supersonic aerodynamics and propulsionproblems. For some time it has been evident that addi-tional supersonic facilities are needed for deve~opmentand evaluation purposes as welI as for research. Fromthis need has evolved what is Imomn as the ‘~nitaryWind Tunnel P1am” Enabling legislation for this planbecame public Iaw on October 27,1949.

The history of the Unitary Phm goes back to late1945 when the military services and the Committeestudied the possibiIit.iesof supersonic flight in its effecton the research, development, and evaluation effort re- “” -quired to insure leadership of the United States in theevolut.ion of aircraft and missiks. The conclusions ar-rived at, including those of the Guided Mkiks Corn- _.mittee of the Joint Chiefs of Staff, concerning their

1

2 REPORT NATIONALADVISORY

special wind tunnel requirements, were available at theApril 1946.meeting of the Committee where it WRSagreed that the recomm&dations of all figencies shouldbe coordinated to eliminate duplication and nonessen-tial items, and to evolve a single plan for the Unitalstates.

The desired coordination was effected by specialpanels of the Committee studyirqg the questions in theperiod April 1946 to Jannary 1947. The resultingUnitary Phm was approved by the Committee on Janu-ary 24, 1947, and was forwarded to the Research andDevelopment Board of the National Militmy Establish-ment (then the JRDB ) and -wasapproved by the”headsof the armed services. The plan aimed at the fme-seeable needs of the country in the next 10 years; itrecommended allocation and operating responsibilitiesamong the hTcmy,Air Force, and hTACA for an in-tegrated wind tunnel construction program. Thesewincl tunnels will be available for the use of all inter-ested agencies and the aircraft industry. Provisionwas made for improved resenrch facilities at univer-sities, not only to perform productive research but alsoto assurean output of qualified aeroclynamiciststo stuffthe tunnels contemplated under the Unitary plan.

Many problems remain to be solved before tacticallynseful aircraft capable of sustained supersonic flightcan be produced. The outstcmding problems involve Rbetter understanding of the transonic speed regionthrough vvhich supersonic aircraft must pas% and thedevelopment of proptision systemsgiving higher thrustfor longer periock of time, at increased efficiencies.

In the tranxmic speed region, an airpkme encountersa mixture of subsonic and supersonic flow. The es-tablishment of the physical laws governing such mixedflow will be extremely important. Since the study oftransonic flow in conventional wind tunnels is not pos-sible, the development of new experimenttilmethods andfac.ilities is required.

In the pnst few years the advent of new forms ofpropulsion challenged the resourcefulness of the aero-dynamicist to utilize effectively the high thrusts madeavailable. The challenge is no-w somewhat reversecl,and it is necessary thut means be found to provide im-proved propulsive systems for ~ircraft being designedfor transonic and supersonic flight. Sufficient thrustis now available for short periods from rocket enginesand jet engines with thrust augmentation arrangements.Progress is being made toward the development of ade-quate propulsion systemshaving the hig~ efficiencyncc-,essary for flights of reasonable duration. WThatmustbe done is clear, but the problems are exceptionally dif-ficult and intensive research is required for their solu-tion.

In addition to the primary problems of high-speed

COMMITTEE FOR AERONAUTICS

aerodynamics and propulsion, a considerable effort isrequired in the numerous and extensivo fickle of com-plemenhwy research that are equally important to thoachievement of useful supersonic flight. Thus, in-creased emphasis is being given to research on the prob-lems of aircraft construction including such subjectsas aeroelasticity, aerodynmuic and impnct loads, struc-tural etliciency,and materials. Attention is also beMggiven to research on such operational problems as icing,fire prevention, atmospheric turbulence, and emergencyescape from high-speed aircraft.

The work of the Conunittee is in genend directedtoward the over-all objective of improving the per-formance, efficiency, and safety of both civil and mili-tary aircraft and of disco~ering ancl applying ncwscientific knowledge eesential to continuing Amcricnnkadership. The immediate objective is to solrc, asquickly as facilities and personnel permit, the most,pressing problenls attendrmton high-speed ffight.

A matter of current interest is the ~pplimtion ofturbopropellers and turbojets to transporl aircrafLThe British Governnlen~ through the Ministry of Sup-ply, several years ago sponsored the development ufnew types of power plants solely for transport.use, cIndfhmced the developnwnt of several transpmi oircrnf~incorporating these engines, The design and construc-tion of such airplanes in the United States is dependentmore on finding an acceptable method of financing ofprototypes than on additional research. $uccessfulcommemial use of such aircraft will depend, however,on research to solve tile many operationnl problems ofhigh-speed transport airplanes.

There is one factor in the administrateion of resmrchthat should not be overlooked. This is the extrcmopressure which arises, when budguts must be curtailed,to approve only thow research projects which have animmediate bearing on current development. 111thelong run this is a fahd policy. Research nufurally learlsdevelopment, If the reverse were attempted, only mi-nor improvements of existing types would result. Pro-curement-mindecl, short-range research could neverproduce such mdicnl developments as supersonic flight,atomic power and radar. There is no surer wny tofall behind thn to perpetuate the old and f(]rego thenew by thinking only of today% production Dnd pro-curement problems.

Parts I, II, and HI of this annual repopl present ar6sum4 of the scientific activities of the Commiltcej adescription o&the Committee’s organization and mem-bership, and the financial report fur the fiscal year 1949.

Respectfully submitted.

JEROMEC. HUNSAKKR,Chairman.

Part J—TECHNICAL ACTIVITIES

RESEARCH ORGANIZATION MTD PROCEDIJRES

COMMITTEE IABOIMTORIES

Research of the National Advisory Committee forAeronautics is conducted largely at its three lAora-tories-Langley Aeronautical Laboratory, LangleyField, Va.; Ames Aeronautical Labomtory, MoffettField, Calif.; ~nd Lewis Flight Propulsion Laboratory,C1eveIand, Ohio. A subsidiary station is located atlYallops Island, Vs., as a branch of the Langley Lab-oratory for conducting ressarch on models in flight inthe transcmic and supersonic speed rang= At MurocLake, Oalif., is located the NACA Iligh-Speed F1ightResearch Station for research on tmnsonic and super-sonic airplanes in flight. The totnl numb+r of en~-ployees, both tecbnical and administrative, at these firestations and headquarters in Washington was 6,93S atthe end of the fiscal year 1949.

TE$HNICAL COMMITTEES AND RESEARCHCOORDKNATION

h carrying out its function of coordinating aeronau-tical research the Committee is assisted by u group oftechnical committees and subcommittees. The membersof thesa committees are chosen for their particularknowledge in a specific field of aeronautics. They areselected from other Government agencies concernedwith aviation including the Depmtment of Defense,from the aircraft and air tmnsport industries, and f romscienti.tlcand educational institutions. These commit-tees protide for the interchange of ideas and preventionof research duplication except where parallel efforts aredesired. There are four technical committees underthe National Advisory Committee for Aeronautics:

1. Committee on Aerodynamics.Q. Committee on Power Plants for Aircrafi.3. Committee on Aircraft Construction.4. Committee on Operating Problems.

Each committee is supported by three to eight technicalsubcommittees.

In mlclition to the four technical committees, there isan Industry Consulting Committee established to twsistthe main Committee in formulation of general policy.Membemhip of this Committee as viell as the technicalcommittees and subcommittees is listed in Part II ofthis report.

Re~earch coordination is fither efiect~ firough di5.cnssionsbetween Committee technical personnel and theresearch stnfls of the aviation industry, educutional andscientific organizations, and other aeronautical agencies.hTumerousconferences me held at Committee labora- ‘-tories to examine research being conducted by theA’.$C.\ and to see that. the proper Government andprimte organizations m-ereceiving full benefit from it.The Research Coorclintition Office is f urther assistedbya west coast representative who maintains close conttictwith the aeronautical research and engineering stuffs ofthat geographical arm.

RESEARCH SPONSORED IN SCIENTIFIC ANDEDUCATIONAL INSTITUTIONS

To utilize most effectively the aeronnntictd researchtalents and facilities of the Nation, the hTACA sponsorsresearch in universities and other nonprofit scientificinstitutions. Through this sponsorship the N’ACA hasaccesston diversity of specialized talent in mathematits,physics, and engineering, which has contributed much~aluable research in many fiekts of aeronautical im-portance. By thus tapping a reservoir of specializedcompetence and unique research fmciIities-which wouldnot otherwise have been brought to bear on pressingaeronautical problems, it is possible to complement theresearch carried on in hrACA labomtories. This ac-tivity has the additional desirable advantage of training~gradnatestudents in practical research techniqu~=.

Tmnsonic aerodynamic research, and instigationsof helicopter characteristics, boundm-y-layer flow, thenature of turbulence+and the physical properties of nipunder the extreme conditions of very high dt itude andspeed Imve been instituted. ‘The development and ew~l-uation of high-temperature alloys and ceramic coat-ings for turbine blades in ~gpm-turbinepower plants arecontinuing under hTACA sponsorship, and the proper-ties of aircraft structures and structural materials, andthe mechanisms of failures in each, are under instigat-ion in a number of institutions. Problems involvingbearings and lubricants, pressurized cabins, combustion,m-d personal aircraft opemt ion are also included in theprojects supported by N’ACA centracts. These vmi-ous research projects are described in greater detail

8


under the headings of the committeesand subcommitteesconcerned.

During this year the .NAC!A lMSsponsored new re-search on fundamental aeronautictd problems at theNational Bureau of Standards, Brown University, Bat-t.de Memorinl Institute,Polytechnic Institute of Brook-lyn, California Institute of Technology, University ofCalifornia, Cornell University, Forest Products Labo-ratory, Georgia Institute of Technology, Harvard Uni-versity, Iowa State Colleg~ Johns Hopkins Univer-sity, Masaclmsetts Institute of Technology, Universityof Michigan, University of Minnesota, Mount Washi-ngton Observatory, University of Notre Dame, OhioStnte University, Oregon State Ckdlsge,Princeton Uni-versity, Stanford University, Syracuse University,Agricultural and Mechanical College of Texas, nndUniversity of lQashington.

RESEARCH INFORM.ATION

Research results obtained in the Committee’s labora-tories and through research contracts are distributedin the form of Committee publications, Formal Re-ports, printed by the Government Printing Office, con-tain unclassified information and are available to thegeneral public from the Superintendent of Documents.Technical Notes, released by the Committee in limitednumbers, also.contain unclassified research resuks of amore or less interim nature and are distributed to in-terested organizations throughout the country. Fre-quently-,research results which -willultimately be pub-lished in Report form are issued initially as TechnicalNotes in the interest of speedy diseanination of datah American technical. people and organizations.Translations of foreign material are iesued in the formof Technical Memorandums.

In addition to unclassified publications the Commit-tee prepares a large number of reports containing clas-sified research information. For rensons of nationalsecurity, thesereports are controlled in their circulation.From time to time the classified reports are examinedto determine -whether it is in the national interest-todeclassify them. If it is found desirable to declassifythe reports, they. are then published as unclassifiedpapers,

Another important means of transmitting qui@lyand etliciently the latest information in a particularfield of research directly to d&igners and engineersworking in that field is the holding of technical con-

COMM.ITTEEFOR AERONAUTICS

ferencw. from time to time at an appropriate NACAlaboratory. Several conference of this natUN wereheld (luring the past year.

The Office of Aeronautical Intelligence was estab-lished in 1918 as an integral part of the Committee’sactivities. Its functions are the collection and classi-fication of tec.hnicalknowledge on the suhjcc~ of atwo-nauti~ including the results of rcsenrch nm.1mpcri-mental -work conducted in all parts of the world, andits dissemination to the Department of Defense, air-craft manufacturers, educational institutions, and otherinterested people. American mld foreign reports o~J-t.aineil are analyzed, classifieit, and broughL to theattention of the proper persons through the medium ofpublic and confidential bu]]etins.

AERONAUTICAL H+WENTIONS

By act of congress, appro~’ed July 2, 1!)20 (U. S. C.title 10, sec. 310-r), an Aeronautical Patents and De-sign Bo~rd was established consisting of the AssistantSecretaries for Air of the Departments of War, Navy,and Commerce. In accordance with that act asamended by an act, approved March 3, 1927, theNational Advisory Committee for Aeronautics ischarged with the function of analyzing and reportingupon the technical merits of aeronautical inventionsand designs submitted to any tigency of the Goww-ment. The Aeronanticul Ptitents and Design hoard isauthorized, upon the favorable recommendation of the~ommittee, to “determine whether the use of the designby the Government is desirnble or necessary am] evalu-ate the design and fix its worth to the United States inan amount not to exceed $75,000.”

Recognizing its obligation to the puMic in this re-spect the Committee lMS continued to accord to “allcorrespondence on such matters full considcrntion. A1lproposnls receivec? have Leell carefully an~lyzcd nndevaluated find the submitters l~are been advised w)]~-cerning the probable merits of ~heirsugge.st.icms.Manypersonal interviews have been granted invcntma whovisited the Committee’s offices, and technical infurma-tion has been supplied when requested.

* * * ● *

The following detailed summnry of research, com-pleted during the fiscal year 1949, is orgnnizcd to reflectthe areas of research over which each technical com-mittee and related subcommittee have cognizance.

REPORT NATIONAL ADVISORY COMMITTEE FOB AERONAUTICS 5

AERODYNAMIC RESEARCH

F1ights of man-carry@ aircraft at speeds greaterthan the speed of sound have up to the present timebeen of very limited duration. Much ressarch remainsto be accomplished to make possible the design of morepractical tmnsonic and supersonic aircraft. While realprogre= has been macIe during the past year in explo-mt ion of new ideas in high-speed aerodynamics, con-siderable effort has also been expended in obtainingclearer undemtancIings of previous research findingg.ln view of the present nature of the problem, theX~C.$ has undertaken extensive studies of tmnsenicand supersonic nir flows with n vie-w to providing ad-ditional aerodynamic information required for airplaneand missile design. h’ew and uncon~entional high-speed airplane configurations ha-ie further dictated thatadditional emphasis be placed on studies at subsonicspeeds of take-off and lancling characteristics. Studiesof subsonic boundary layers have likewise been ex-tended to provide a more thorough understandi~o ofthe phenomena as related to the new confqyrations andto assist in achieving improvements in performance ofmore conventional aircraft flying at subsonic speeds.Explomtory research on the nature of nir flow at ~eryhigh supersonic speeds has also been undertaken andthe development of new research equipment for thispurpose is also under way.

It is apparent from the details of the report whichfolio-iis that the term “aerodynamic research” has bwnapplied in a general senseto broad areas of the NTACA’Sscientific etiort. Accordingly, the scope of the currentactivit ies of the Committee on Aerodynamics includes

COMM.I’IT13E ON

AirfoiIaBecause of the need for airfoil data at high Reynolds

numbers the aerodynamic characteristics of a numberof NACA 6-series airfoils! in both smooth and roughconditions, were determined experimentally at Reynoldsnumbers of 15,000,000, 20@-0#100, and 25,000,000, andreported in Technical h70te 1773. The investigationincluded a systematic study of the effects of airfoilthicknessratio, thickness distribution, and camber uponthe aerodynamic characteristics of the airfoils at thedifferent Reynokls numbers. One of the airfoils wasakmstudied with a split flap. A particularly interestingresult wns the relatively large increase in the maximumlift coefficient of the 6-percent-thick sections as theReynolds number vras increased from 15,000,0cKlto95,000,000.

A compilation has been made of data obtained fromtests in the Imngley two-dimensional low-turbulence

consideration of many problems of flight experiencedat submnic, tmnsonic, and supersonic speecls-which aredirectly, or in some cases indirectly, related to aerody-namics. The Committee on Aerodynamics is aided inits retiew of this broad field of research by the Subcom-mittees on F1uid Mechani~ l%gh-Speed Aeroiiynam-ics, Stability and Control, Internal Flow, Seaplanes,PropelIers for Aircraft, Helicopters, and the SpeeialSubcommittee on the Upper Atmosphere. During thepast year a new Subcommittee on F1uid Mechnnics wascreated to review and coordinate the rapidly expandingresearch in this field. The Special Subcommittee on Re-search Problems of Transonic Aircraft Design, men-tioned in the previous annual report, -wasdischarged inview of the completion of its special assignment. TheSukwommittee on Eigh-Speed Aerodynamics vine r.s-

..—

organized in order that it might devote more attention Tto the desiaa problems of missiles and airplctnes, and -‘“assume the duties previously assi~~ed to the SpecialSubcommittee on Research Problems of Transonic Air-craft Design. Resenrch on air loads, effects of wingflexibility, clyn.nmic maximum Iift, flap effectiveness,ancl pressure distribution studies are c~iscussedin thesection “Airframe Construction Research” under activ-ities of the Subcommittee on Aircraft Loads.

In order to promote early use of the research results,a technical conference on supersonic aerodynamics washeld early in the fiscid yenr at the Ames Laboratory,with representati~esof the militnry services nnd the air-craft industry. Some of the Committee’s recent workin aerodynamics is described in the following sections. —.—

AERODYNAMICS

tunnels of a Iar=n number of tiellaneous airfoils.The airfoiIs consist of 14 modified or unconventionalNK.A 6-series sections and 5!0other sections of specialdesign. The aerodpunic characteristics of these nir-foils extend over a range of Reynolds number from3,000,000 to 9,000,000. .

The accuracy of the method described in Report 824(“Summary of Airfoil Data”) for rapidly calcrdatingthe increment in the velocity distribution about a sym-metrical airfoil due to angle of attack has been inves-tigated. An analytical study was made of the accuracyof the method by the use of the exact theory of Theo-dorsen and Garrick for the potential flow about nrbi-trary airfoils. The resuIts of the study reported inTechnical Note 1884 show that the method of Report624 evaluates the tied of angle of attack on the netvelocity at any point of a symmetrical airfoil with amaximum error that is proportional to the cosine ofthe angle of attack

6 REPORT NATIONALADVISORYCOMMITTEE FOR AERONAUTICS

A theoretical method has beenstudied at the LewisLaboratory for calculating the velocity distribution onarbitrary airfoiLq in closed subsonic wind tunnels byconformal mapping. This study is reported in Tech-nical Note 1899.

High-Lift DevicesIn an effort to improve the maximum lift and stalling

characteristics of moderately thin nirfoilsl modificat-ions of the contour very near the leading edge of anNACA 631-012 airfoil section have been investigated inthe Ames 7-by 10-foot wind tunnels. The modificationsincluded iucreased leading-edge radii and camber andseveral nose flaps with increased leading-edge radii.The basic airfoil had a leading-edge radius of 0.0109chord and stalled abruptly at a lift coefficient of 1.36.No turbulent seprmaticn was evident before the stzdland the stall occurred because of a sudden fa,iluw of theseparated 1aminar boundary layer near the leading edgeto reattach to the airfoil surfuce. Maximum lift WMfollowed by a large loss”tiflift. Increasing the leading-edge radius increased maximum lift and the ang~e ofattack for maximum lift; however, the stall remainedabrupt with a large loss of lift beyond the maximum.The nose flaps and increased camber near the leadingedge in conjunction with fin increased Iemdmg-edgertdius provided additional increases of maximum lift;however, again a large lose of lift fgllowed. Witl~ aleading-edge radius of 0.035 chord added completelybdow the upper surface of the bmic airfoil, a maximumlift coefficient of 1.71 was obtained. Some of the modi-fications teeted initiated turlndent separation near thetrailing edge along wit~~_theincr~se of maximum ljft;however, the stall appeared to be controlled by a suddenfuilure of the separated laminar boundary layer nearthe leading edge to reattach to the airfoil surface.

Results have reccdy been obtained of tests in theLangley two-climensiomd low-turbulence tunnels ofleading-edge slats on two airfoils of 9- and 19-percentthickness to investigate means of improving the maxi-mum lift and stalling characteristics of thin wings nec-essary for high-speed flight. The results indicatedthat.,in combination with a split trailing-edge flap, theleading-edge slat increased the maximum sectiou liftcoefficient by 0.81 and 0,60 on the 9- and 12-percent-thick airfoils, respectively. The slats also increasedthe angle of stall and caused the stall to become moregradual.

Although sharp-edged airfoil sections offer consid-erable promise for application to certain supersonicaircraft, they have a low maximum lift and a rapidincream of drag ]tith lift at low sqyyiie. An investiga-tion of nose and trailing-edge flaps on a modified dou-ble-wed% section was therefore undertaken in the Ames

7-by 10-foot wind tunneI to ewluak the elhxis of theseflaps on the aeroclynrunicchamcteristics of the section.

The basic airfoil section with flaps unddhxt d lmd nmaximum Iift coefficientof 0.S4, With the trailiug-cdgoflap deflected 60° and the O.l&chord nose [Ial} deflected30°, a maximum lift coefficient of 1.96 was olhincd.Variation of the chord of the nose flap had little effecton the mrminlumlift; however, the effect on the angleof atttick for zero lift was mther pronounced. In-creasing the deflection or the chord of the nose il.apor the deflection of the trailing-edge fltip resulted inmore negative pitching moments. ConsiderAlo reduc-tions of drag at high lift codieients were noted forsuitable combinations of nose-fhtp A trailing-edge-flnp deflections. The lift coefficient for minimum drugincreased with increasing chord of the nose ilnp withthe net result that the largest chord flaps provided theleast drag at the highest lift coetliciente.

WhgsAn exploratory investigation to determine the wwo-

dynamic effects of camber on a 60° apex trinugular-wing model has been couducted in the LangIey 300-n@~7- by 10-foot tunnel. Camber variation was nccom-plishecl through the defhwtion of full-spnn round-lead-ing-edge flaps and ’25° be~elell-leadil~g-e{lge ilnps on aflat-sided, trimlgular-plan-fcmn wing.

A 63° sweptback wing being studied in several of tlmfticilities of the Ames Laboratory has been investi-gated in the 7- by 10-foot wind tunnel to evaluate theeffectivenew of various controls and Iift-iumeasing de-vices. The results indicrtte a rwlical reductiuu of lon-gituclintil stability at moderate lift codicients for lhobasic wing. The reduction of stability was roughlyequivalent to a 50-percent mean-aerodynamic-chordshift in neutral point. The large reduction of longi-tudinal sttibility can be delayed to a higher lift cocAl-cient by incorporating either a full-span now flap ordrooped nose with a half-span split flap at the trailingedge and utilizing an eleven for hdance.

The stfilling and maximum lift characteristics ofwing plan forms suitable for current high-speed air-plane designs have required a hwge runountof researcheffort. These characteristic are strongly nflected. t.JyReynolds number. Facilities capable of tests at essen-tially full-sealc Reynolcls numbers are required. lte-sults from the Lungley low-turbulence, Langley full-scale, Langley 19-foot, Ames 40- by 80-foot, und A meal%f oot tunnels can be used to predict the bchnvior ofair flow on wings at landing speeds,

A series of swept wings has been designed cm thebasis .of the analysis presented in l’ethnical Note 177S?to determine at large scnle the extent to which camberand twist will improve the low-speed characteristics of

REPORTNATIONALADVISORYCOh.1311TTEEFOR AERONAUTICS 7

thin sweptback vriuga. Wings having 45° and 60° ofsweepback and three -dues of twist and camber havebeen inves~cated in the Ames 40-by 80-foot wind tun-neL The results show that even moderate twist andcamber? such as appear suitable for high-speed flight,-will produce marlwd impro~ements in the lo-iv-speedcharacteristics of such wingF. It is anticipated thatfurther refinement viill enable full realization of thetheoretical possibilities of these -wings which are con-siderably better than those of untwisted, uncamberedswept wings.

An analytical study has been made of the landing-flare paths of hypothetical airplanes covering a widera~~e of masimum lift coe5cient, wing loading, andlift-drag ratio. Generalized charts as well as a step-by-step method of analysis are presented in Technicalh~ote 1!330for predicti~u the power-off landing-flarecharacteristics covering the conditions of various typesof high-lift devices. From power-off considerations,airplanes having -rery low Iiftdrag ratios and highstalling speeds require exceeshe horizontal hmding dis-tances?high ratea of descent, and high altitudes at thestart of the flare maneu~er. These landing considera-tions are expected to have considerable influence on theultimate sdection of wing conflgumtions for high-speedairplanes.

The lovi-speed characteristics of an equilateml tri-angular wing having 10-percent-thick biconvex sectionsha~-ebeen determined in the Langley full-scale tunnel.The effects of flaps on the maximum lift coefficient andon the lift-drag ratio were determined, and an analysiswas made of the cmresponding pwer-off landing char-acteristics. The effects of a fin on lateral and direc-tional stability were also determined.

The effects on maximum lift of ~ariations in the spanand deflection of tmiling-edge split flaps, operating inconjunction -witha 0.59-span leading-edge flap on a w5ngof 42° svreepback and aspect ratio of 4, have been in--wstigated in the Langley 19-foot pressure tunnel. Themasimum-lift results were evaluated in terms of thehtnding characteristics in order to define the optimumcombination of leading-edge and traili~~-edge flaps.

An investigation was made in the Langley two-dimensional lo-iv-turbulence pressure tunnel of a semi-span model of a 42° s-weptbtickwing of aspect ratio 4,which had pre~iously been tested in a full-span arrange-ment in the Langley 19-foot pressure turmel, to obtainan indication of the vaIidity of the semispan methodof obt~ining aerodynamic data in this particular ar-rangement. This investigation indicates that data ob-tained from semiepan-=ing tests may be expected tobe in good a=mment with data obtained from full-span tests of the wing alone except for unusually sensi-ti}’e configurations, -where the Iift distribution is such

that small disturbances produced by the tunnel-wallboundary layer may cause a radical change in the loca-tion of the original stall or in the manner in which thestall progresses.

—

Boundary-Layer InvestigationsBoundary-1ayer utudies. A continued study of the

boundary-layer and stalling chamcteristics of airfoilsections in the Ames 7- by 10-foot wind tunneki hasadded much to the understanding of the mechanism ofthe stall of thin airfoils. It has been shown that thereare, in general, three types of airfoil staLI: (1) Thatre.wdting from turbulent separation beginning near thetmiIing edge and gradually progressing forward alongthe airfoil upper surface as the angle of attack is in-creased; (2) that resulting from the sudden failure ofa separated bounckwy layer near the leading edge to re-attach to the airfoil upper surfuce at the angle of attackfor maximum lift; and (3) that resulting from theseparation of flow from the leading edge but reattach-ing to the airfofl surface at positions progressivelyfarther downstream as the angle of attack is increased.The first type of stall appears on relatively thick air-foil sections and the last type is evident on thin, sharp-edged sections. The intermediate type appears on sec-tions of moderate thicbess. These types of stall arefound separately or in combination; depending on theairfoiI under consideration.

The results of Technical Note 1894 indicate that foran NACA 63-009 section there was a short region ofseparated laminar flow near the leading edge prior tothe attainment of maximum lift. The separated regiondecreased in extent as the angIe of attack was in-creased. Maximum lift was attained when the sepa-rated kuninar botidary ~ayer failed to reattach to theairfoil surface. Other tests have shown that, with amodified double-wedge section, a form of separation ap-peared at the leading edge for a very low angle of attackand the separated region increased in extent as the angleof attack was increased. The flow over the h’ACA 63- ...009 section for angles of attack greater than that formaximum lift -wassimilar to the flow over the double-wedge section for angles of attack Ieas than that formaximum lift. Tests of an NACA 64AO06 section(Tecbnical Note 1923) have indicated that, at an tingleof attack of about 5°, the flow changed abruptly froma type similar to that for the NACA 63-009 sectionbefore its stall to a type similar to that for the modifieddouble-mdge section before its stall.

Bounda&ayer control. h extensive study of theuse of boundary-layer control as a means of improvingthe aerodynamic characteristics of airfoil sections isunder way in the Langley Iow-turbulence section.

h investigation was made to determine the effective-n~ of boundary-layer control together with relatively “”--

8 REPORTNATIONALADVISORY

small deflections of n plain ffnp m a means of increasingthe lift-drag ratio. The boundary-layer control wasapplied through a single suction slot located just be-hind the hinge line of the plain flap. The airfoil em-ployed in the two-dimensiom-d investigation -was theNACA 65, 6-418. The rewdts indicate tlntt the maxi-mum ratio of lift to total drug of finite-span wingsmade up entirely of NACA 65, 3418 airfoil sectionswould not be improred by this type of boundary-layercontrol if the wings were in the aerodynamicallysmooth condition. For the rough surface condition, theresults indicate that the boundary-layer control wouldincrease the mmrimumratio of lift to total drag.

Wing sections suitable for high-speed applicationsusually stall abruptly with a large loss of lift at rela-tively low values of maximum lift bemuse of the failureof a sepmated h-tminarflow near the leading edge toreattach to the airfoil surface. It has been demon-strated previously in the Ames 7- by 10-foot wind tun-nel that a suction slot near the leading edge was effectivein delaying the complete flow separation, and increasedthe maximum lift about one-third above that mf thebasic section. Turbulent separation occurred at thetrailing edge prior to the attainment of maximum lift;however, it could not, be shown that the stall was en-thdy the result of turbulent separation. To determinewhether or not the nose slot was capable of holding theflow on the. surface at higher values of lift, a secondsuction slot was installed at the midchord of the modelto control the growth of tle turbulent boundary layerover the rem portion of the model. It was found thatthe operation of the midchord sIot in conjunction withthe nose slot resulted in substantial gains in maximumlift over that obttiined with nose suction alone. Thecause of the stall with combined nose and midchordsuction is uncertain; however, it was demonstrated that,the nose suction slot combined with the midchord slot-waseffective at lifts ~aater than maximum lift -withthe nose dot alone,

An exploratory investigation was made at the Lang-ley Laboratory of boundrtry-layer control through aporous leading edge as a means of delaying leading-edge separation and thus increasing the maximum lift,coefficient. The NACA 64A212 airfoil was employedin the investigation. The results, which are reported inTechnical Note 1741, indicate thnt the effectiveness ofthe boundary-layer control in improving the maximumlift coefficient is about the same as would be obtainedfrom a vrell-designed leading-edge slat.

A study has been undertaken at the Ames 40-by 80-foot wind tunnel to determine the possible gains resrilt-ing from the applicationof bound! ry-layer control to amveptbackwing by means of-porous suction at the lead-ing edge in conjunction with circulation control. Pre-liminary resultshave estal.iishedthat the porous suction

COMMITTEE“FORAERONAUTICS

must beapplied over the entire span of the lcwling edgoand over about 5 percent,of ihe chorcl. IYith such cort-trol it was found possible to &lay the appc:trance 0[leading-edge sepnration to wt least the OXLCH1possiblewith leading-edge ffaps. With the general requirwmmtsdetermined from the preliminary tesh it is anticipatedthat further studies will yield n distribution of leadingedge su!itionproducing even more fttvomblc results.

The problem of reducing the lmofilc-drrLgcocKkiel~tof airfoils by increasing the relative ex(cllt uf htminarflow wa.s.consideredin some detail at the Y.alq+ey Lab-oratory. A two-dimensional wind-tunmI invest.igaticmrepelled in Technical Note 1905 vnasmade of an XAC.i64AO1O airfoil having a porous surf}lce of sinkwdbronze to determine the reduction il] section drag codTi-cient that might be obtaineil at large Rqmoltls l~umlwrsby the useof continuous boundary-layer suction throughthe surfaces of the mocle}. Combined WAC and SUC[iundrags lower than the drag of the plwin airfoil weroobtained up to Reynolds numbers of R,000,OOO.‘Nwmodel iurftices were neither aerodynmnicttlly smoothnor fair, -whichindicated that the suction had some st:L-bilizing effect on the laminar boundary hlycr. Aret(lriqgreductions could not be obtttined with thk model aI,Reynolds numbers higher than 8,000,000.

The study of the application of boundary-hlyer con-trol to a sweptforward wing has been comple[wl at lhcAmes 40- by 80-foot wind tunnel. Satisfactory h?adilJg-edge flaps were found nud boundary-layer control skiswere placed titvarious chordwise and spnnwise positionson the wing upper surf me. The optimum posi[ion furapplying boundary-layer centrol, howevm, wtis fottnc,lto be a slot placed in the fuselage next to ~hewing uppersurface and extending a short distance fore and af[ ofthe hinge line of the nose flap.

In an effort to clarify the presentstatusof resmrch onboundary-layer control and its possible applicntions inaeronautics, a survey and evaluation were made of theresults obtained from numerous individual investiga-tions of various app]icntions of boundary-layer con[rol.

The results of the survey indicate th:k sullic.ient.in-formation is not available to permit the pr~~cticalappli-cation of some types of Ixxudary-lttyer control and thrttother types do not promise sutlicient,incroascs in air-plane performance to warrant their use. The applica-tion of boundary-layer control which appears to offerthe most immediate promise of improved airl)lane per-forrmmce is the use of suction to eliminate turbulentseparation over the rear of very thick uirfoils. l’hoprevention of turbulent septiration on such airfoils per-mits their use as root sections of wings having very highaspect ratio. This application should result in sub-stantial improvements in lift-drag ratio and range oflong-rangerelat.ively slow aircraft.

REPORTNATIONALADlT30RY

Research on the use of multiple slots for the controlof the laminar boundary Iayer has shown in general thatat low Reynolds numbers it is possible to extend thelaminar la-yerin a region of adverse pressure gradientpractically to the trailing edge of an airfoil with a smallexpenditure of power, such that large net drag savingswere realized. Studies are under way in an attempt toachieve extensive laminar flow at flight values of theReynolds numhws.

Research Equipment and Techniquesiyele trind tunnels. SeveraI new supersonic research

facilities viere put into operation during 1949. Amongthese facilities viere three large supersonic tunnels, the&by 4-foot viincl tunnel at the Langley Laboratory, the& by 6-foot wind tunnel at the Ames Laboratory, andthe 8- by (1-foot wind tunnel at.the Lewis Laboratory.The first two of these tunnels are of the varinble-pres-sure type which permits in-restigationsto be carried outover a range of Reynolds number. A range of super-sonic Mach number is provided for in all three tunnels.In the Langley tunnel, Mach number variation is ac-cmnplished in fixed incrementsby means of flexible wallswhich are held to the correct shape by means of tem-plates; the Lewis tunnel utilizes flexible -wallswhich arecontinuously adjustable; and the Ames tunnel utilizesa new type of asymmetric supersonic nozzle which, likethe Lewis arra~aement, permits the Mach number ofthe tunnel to be varied continuously.

Blomdozrn tunnel instrumentation. MIUly mindtunnels of the blow--down type, in which air is com-pressed in a large chamber and then released throughthe tunnel, are limited to test runs of a ~ery short durn-tion. 3feasurements in these tunnels are either of tran-sient phenomena which are continuously and rapidlychanging or of quantities which attain a steady valuefor onIy a fraction of a second. One of th= tue~has a steady-state run of approximately 0.02 secondduring -whichmeasurementscan be made. The instru-mentation included a strain-gage sting bahmce formeasurementof dragon the model, shadowgraph equip -ment for obta@u photographs of the rapid develop-ment of the shock pattern caused by the model, andcontroLsto synchronize the instruments within the briefrunning time.

wind-tunnel corrections. IiItheLangley full-scaleanalysis section several studies have been made of theproblem of corrections for wind-tunnel-mall interfer-ence on test re.sult~ In Technical Note 1748 is givena general graphical procedure for calculating tunnel-induced-npwash angles for s-wept and yavred wings,both at the -wing and at the tail. The required chartsfor a number of existing wind tunneIs are included inthe paper. In Technical Note 1826an exhaustive analy-

COMMITTEE FOR AERONAUTICS 9

sis has been made of the -wind-tunnel interference inopen wind tunnels -with consideration for the effect ofthe closed entrance and exit bdhi. This study was madeprimarily in order to determine corrections for heli-copter tests in the Langley fnll-scale tunnel, where thelarge rotor disk extends so far forward that the presenceof the entrance bdl cannot be negkcted. The reportdiscussesthe basic phenomena involred, deriws methodsfor determining the interferenc~ and presents manycalculated results.

Computations have been made in the Langley 7- by10-foot-tunnels section in which the numerical vahmsof the calculateclboundary-induced-upwnsh angks nec-e=ary for the determination of the jet-bounclary cor-rections for swept reflection-plane models mounted ver-tically in 7- by 10-foot, closed, rectangular wind tun-nels ha-rebeen e-raluated. A few calcuIatiom made byusing these values of upwash indicated thatj for planforms having taper ratios of about %, s-weephas e+sentially no effect on the correction. lhcept for ex-treme cases of inverse taper the collectof sweep on thea-rernge induced angle appeiim to be less than 10 per-cent for sweep angles up to 60°. The restits of thisinvestigation are presented in Technical Note 1752.

Study of airspeed indicator installations. Calibra-tions of the static-pressure or “position” errors of theservice airspeed installations of 10 present-day air-planes are presented in TechnicaJ Note 1892. Tests wereconducted from speeds near the stall to maximum indi-cated speeclsnot exceeding 260 miles per hour. Analy-sis of the data presented showed that the static-pressureerror for static vents on the rear section of the fuselageremained approximately constant -withangle of attackand became more negative -with flap deflection. Thestatic-pressure errors for the wing, fuselage-nose, andvertical-tail insta~ations became more negative with in-creasing angle of attack and more positive with flapdeflection; the effect of engine power for these installa-tions followed no consistent trend.

Response of pre3sure-measurkg systems. C)fmajor interest in many test indal]ations is the responseof pressure-distribution systems to rapid~y varyingpressures,both where thesepresanreemust be accuratelymeasured and where unwanted owillations must be ill-tered out or eliminated. Technical Note 1S19presentsa method for calculating the response of preeeure-measuring systemsto steady-state sinuosoidalIy varyingpressures. The pressure system is assumed to consistof an inlet restriction, tubing length, and connected in-strument volume. The materiaI presented is limitedby the fact that no theoretical method of predictingthe attenuation characteristics of the tubing is given.This limitation is not severe, however, as these charac-teristics may be experimentally determined for given


tube sizes and pressure frequencies. Experimentaldata for some sample systems tested are presented nndshow good agreement with calculated values. The xe:suks are presented in such fashion that the qualitativeeffect of varying the dimensions of system componentsis apparent. It is therefore possible, once the attenua-tion characteristics of the.tube are determined, to designa system with a required frequency response.

SUBCOMMITTEE ON HIGH-SPEEDAERODYNAMICS

Airfoils and Wings at Transonic SpeedsThe study of airfoils at high speeds has continued

to receive emphasis iu the Committee’s research pro-grams. Several airfoil investigations were completedin 1949, A static-pressure investigation of the tvro-dimensioual flow field in the neighborhood of twoNACA 6-series airfoils at high subsonic speeds wasconducted in the Langley rectangular high-speed tunneland is reported in Technical Note 18’73. Pressure meas-urementswere made by means of wlarge number of ori-fices iu the model end plate which was fitted flush withthe tunnel wall. Reasonable agreement between theoryand experimen~ was obtained for Mach numbers up tothe critical values except at high angles of attack.

A two-dimensional pressure-distribution investiga-tion of NACA 6&-012 and 64,AO12airfoils was carriedout iu the Langley rectangular high-speed tunnel todetermine the effect of removing the cusp from thetrailing edge. A similar investigation on thinner sec-tions was carried out in the Ames 1- by 3~&foot high-speed wind tunnel. in which the NACA 64AI1O and64AO1Oairfoils were employed. A study was made inthe Langley rectangular high-speed tunnel of eight 6-percent-thick airfoils incorporating sharp and roundletiding edges. The aerodynamic characteristics of eachairfoil were determined from the pressure-distributiondata. A new series of airfoil sections, designated theNACA 8-series, w-as designed to have favorable liftcharacteristics at supercritical Mach nmribers. Expec-tations were cmdirrneilby results of wind-tunnel inves-tigation to the extent that little or no vnriation in liftcoefficient was found up to Mach numbers of about 0.9at the constant desi=guangle of attack, It was not foundpossible, however, to improve the lift-curve slope or thedrag at supercritical speedsby use of these airfoils.

The linearized equations of compressible flow werestudied for the cma OLnear-sonic speeds and resultswere obtained for the time-dependent motion of two-dimensional airfoils and for particular steady-statethree-dimensional lifting-surface problems at Mnchnumber 1. These resultshave been reported in Techni-cal Note 1824 Studies in the Langley 16-foot high-speed tunnel of the effects of co.mpressibility on the


maximum lift characteristic of unwept wings havebeen exkirided to ii~clude the effects of deflected splitflaps as reported in Technicnl Note 1759. The flapsmere shown to be effective in producing increases inmaximum lift at all speeds up to the maximum twJ value(M= O.7). Although the flaps increased tlm vrL1uesofmaximum lift over the test speed range, the trend ofmaximum lift with the increasing Mach number wassimilar to that previously shown for plnin wings. l?ur-ther studies on other wings employing different airfoilsections have been macle to investigate thu eflect of air-foil sectiou on wing maximum lift characteristics (Tech-nical hTote1877).

A systematic series of several unswept wings of vnry-ing aspect ratio has been investigated at hmgc scales andhigh subsonic Mach numbers in the Ames l&foot high-speeclwind tunnel. A thin unswept wing of low aspectratio has been investigated at the Ames Laboratory bymeans of the NACA wing-flow method and the resultshave been compared with wind-tunnel results tind with _subsonic and supersonic -wing theory.

The merits of the swept-wing plan form at transonicspeeds hare been established qualittitivdy from boththeoretical and experimental investigrttions. ‘Nw fullexploitation of such plan forms, however, rcquircs fur-ther investigation. Several investigations were madeduring the past year which will add to the body of in-formation required for proper design of such wings.An invwtigation was conducted in the Ames 12-footlow-turbiilence presmre wind tunnel on a swept winghaving 37° svreepback of the leading edge. Tho aero-dynamic characteristics and load distribution for thiswing were measured and compared with theoreticalestimatw for Mach numbers up to 0,94. at constant -Reynolds numbers in the range from nbout 1,000,000trJ3,000,000. A theoretical method for clefhing criticalflow conditions at high Mach numbers was found to bein good agreement with experimental results and thusto offer a satisfactory meansby which the Mach numberfor drag divergence could be estimated for thie wing.Further investigation is required to establish the degreeof applicability of the results to other swept wings andto problems reloted to the effects of fusehtge mid na-celle interference on such wings.

A coordinated research program to determine thocharacteristics of a configuration incorporating a wingof 63° m%epback has been continued. A model of thisconfiguration has been investigated over a wide rangeof subsonic and supersonic Mwch number in tho Ames1- by 3++foot high-speed wind tunnel and mothermodel incorporateing certain special featurcs desigucdto improve its characteristics has been invessigatwl atrelative]y large scale and high subsonic Mach numbersin the Ames 12-foot high-speed tunnel.

REPORT NATIONAL ADVISORY

~ study was made In the Langley E&foothigh-speedtunnel to determine the effects of the addition of a tri-angular mea aheacl of the inboard part of a conven-tional sweptback wing. The addition of this are~formed a wing with two stages of sweepback. Resultswere obtainecl for a Mach number mnan of 0.40 toabout 0.94.

As part of a specinl research program recommendedby the Special Subcommittee on the Aerodynamic Prob-lems of Transonic Aircmf t Design, x systematic seriesof wing-body combinations has been inrestigtatedin theLangley high-speed 7- by 10-foot tunnel over a Machnumber range of about 0.60 to 1.1S,~~ing the transonic-bump test technique, Lift, drag, pitching moment,root bending moment, and the effectire do-wnwashangksand dynamic pressures in regions of possible tuil loca-tions were measured.

The freely falling body technique continued to beused during the pnst year to irrrestigate the effects ofwing sweep, taper, ancl thickness ratio on the zero-liftdrag of a number of wing-body configurations in thetranaonic s~eed rang~

The triangdar-wing plan form continues to be of iu-terest and several instigations have been conductedin the past yw.trat transonic speeds on such plan forms.

Two domnviash investigations were made in connec-tion with the X.-!CA tramcmic research airplane pr-ogram. Calculations were made to determine from lin-earized theory the downwnsh at the tail of the X–1.airplane at supersonic speeds and the effect of the do-wn-wash on the elevator deflection required for trim. De-tailed experimental measurements of downwash anglewere made in the Langley 8-foot high-speed tunnel fora model oft he D–558-I airplane at high subsonic speeds.

Wings at Supersonic SpeedsThe source-distribution method for analyzing the

steady flow o~er thin finite wings at supersonic speedshas been extended in Technical X-ote 1699 to permit theprediction of slowly varying, unsteady load clistribu-tions over finite wings. Similarly, the simplified methodof determining lift distribution for thin three-dimen-sional wings of fairly genertd p~an form has been ap-plied to predict the load distributions for a wing insteady roll and pitch (.Technical Note 16S9).

The explicit evaluation of the suction forces alongsubsonic Ieading ec@s of a family of ~ings at super-sonic speeds (Technical N’ote 1718) led to the conclu-sion that higher lift-drag ratios may be obtfiined withcurved than with stmight-hne, plan-form boundaries.

A theoretical method was developed in Technical hrote1736 for obtaining the aerodynamic forces acting onthin wings in an irrotational nonuniform supersonicstream. In tiddition, the source-distribution method


was applied to estimate the properties of u ring airfoil(Technical Note 167S).

The resuIts of the linearized theory for the loads onthin wings at supersonic speeds hare been comparedwith experimental -raluesobtained in the Lewis 1S- bylS-inch supersonic tunnel at a Mach number of 1.9.Other experiments are being conducted to check theaccumcy of theoretical methods.

Experimental studiw have indicated that the opt in-nunairfoil shape for two-dimensional supersonic flow is notnecessarily that indicated from theoretical considera-tions based on a nonviscous flow. An in-restigation atsupersonic speeds in the Ames 1- by 3-foot supersonicwind tunneIs has indicated that principks other thanthose heretofore considered may lead to airfoil sectionswith improved chamcterist its.

An experimental investigation in the new ties 6- by6-foot supersonic wind tunnel was conducted to meas-ure the load distribution owr a 63° svreptback vring atseveral supersonic speeds. This investigation was partof the coordinated research program on this cor&gura-tion mentioned in the preceding section. Another studyof the same cor@nrat ion to determine Iift, drag, andmoment characteristic has been carried out in the Ames1- by 3-foot supersonic wind tunnel at n Mach numberof 1.5.

An extensive investigation of triangular wings wasmade in the Langley 9-inch supersonic tunnel. Thein-reetigation included tests of 22 trianadar wings of2 airfoil sections and 11 apex angles at Mach numbersof 1.6, 1.9, and 9.4. One series of U wings had double-wedge sections and the other series had sections withelliptical leadi~~ edges.

The downwsh and wake behind unswept, swept, andtrian.gdar wings ha-re been measured at supersonicspeeds in the Ames 1- by 3-foot supersonic wind tunnelNo. 1. The resuIts ha~e been compared with avaiIablelinearized theory.

Bodies and Wing-Body Interference&nalyses are being conducted to determine the load

distributions and the aerodynamic characteristics ofarbitrary thin bodies at supersonic speeds. An approx-imate method for obtaining the flow around thin arbi-trary conical bodies at supersonic speed by the use oflinearized theory is reported in Technical Note 1659.This method was extended to simplify the descriptionof angle-of-attack and yaw effects. Experimental re-sults have been obtuined on an elliptic cone in an inves-tigation conducted to check this theory. A graphicalmethod was presented in Technical hTote176Sby -whichthe approximate pressure distribution on a slender ar-bitmry body of resolution moving at supersonic speedsmay be calculated with appreciab~esaving of tima


l@eriments were conducted on m asymmetricalnonconical body to determine pressure distributions onHtypical fuselage of a supersonic airplane. An attemptto estimate the theoretical lords on this body led to thediscussion of thee-dimensional characteristics pre-sented in Teclmicnl Note 1849. In another investiga-tion the method of churacterietics was applied to thedetermination of the exact nonviscous supersonic pres-sure distribution around bodies of revolution at smallangles of attack, The system developed considers theeffect of the variation of entropy due to the curvedshock and is described along with two prmcticalmethodsfor numerical calculation in Technical Note 1809;

An investigation -wasconducted in the new Langley4-by 4-foot supersonic tunnel to determine the pressuredistribution over the fuseh~geof a supersonic airplanemodel with and without canopies. Experimental re-sults have been compared with theoretical calculationsand analytical procedures have been evolved for thecalculation of canopy presure distributions.

A method has been developed for evaluating fromshadow or schlieren photographs the pressure drag ofaxially symmetric ancl two-dimensional bodies operat-ing with detnched shock. The method vvhich is de-scribed in Technical Note 1808 tin be used also todetermine the extermd drag of supersonic inlets withclettiched shocks and to evaluate the external shocksof perforated inlets

The pressure drngs of a Munt-nose and sharp-nosebody were measured at transonic speeds by means ofthe wing-flow method and the results compared.

Investigations of wing-body and wing-nacelle inter-ference at supersonic and transcmic speeds have beenconducted. Theoretical methods have been developedfor the prediction of the mutual interference betweena body and either a single wing ora cruciform wing atsupersonic speeds. Two reports have been published(Technical Notes 1662 and 1897), giving the load dis-tribution, lift.?side force, pitching moment, and yawingmoment for configurations of themissile type.

An experimental investigation hys been conducted tostudy means for increasing the force-divergence Machnumber of s-wept-wing-body combinations. A methodfor alleviating the adverse interference between sweptwing and body was tried which involved the contouringof the fuselage sides to conform ta the normal path ofthe streamlines of a s-wept-wing. Theoretical calcula-tions of the contours required were dkmssed in a pre-vious annual report. A second method involving modi-fications to the wing-root section was aIso investigatedexperimentally.

The effects of a nacelle on the aerodynamic character-istics of a swept wing have been investigated in the~ngley 16-faot, ]Iigh-speed tunnelup to Mach numbersof 0.61 for the wing-nacelle combination and 0.70 for


the wing done. The results which are published inTechnical Note 1709 show tlmt the presence of Llmnacelle had no effect on the lif t-curre slope of the un-swept wirg, increased the lift-curve slope about 10 per-cent with the wing swept baclc 450, and dccrcascd 1110lift-curve elope slightly with the wing swept forward45°. The presence of the nacelle did not appreciablyalter the stalling characteristics of the -i5° sweptf!Jr-w-ard and svveptl.)ackwings but. mused an nppreciablcreduction in maximum lift for the wing in the unsweptposition. The drag increment due to the nacelle wasgenerally lower for the s-weptconfigurations tlum fur ‘“”the unmvept case. Adtltion of tho nacelle to ilw wingreduced the longitudimd etabi1ity of all the swept wings.

The eyternal-store problem centinues to be of impou-tan.ce. The rocket-prope]led-model technique was uti-lized to determine the drag increments at hmsonicspeeds due to the presence of strut-mounhxl wing tanksof moderate finenessratio on a sweptbtickwing.

SUBCOMMITTEE ON FLUID MECHANICS

Viscous F1OWSA f uncltitnentalkno-wledgc of boundary-layer pl~e-

nomena af,high speeds has assumed increasing impor-tance to the aeroclynamicist. Dnring the pas~ year astudy was made of the behavior of ~helaminar lJound-iry layer in compressible flow, following prmmluresevolved previously for the incomprcsible case; the re-sults were reported in Technical h’ote 1S05. Theoreticalconsiderations indicate that with the usual assumptionsof boundary-layer theory the separation point- cd thesteady compressible larninar boundary lnyer is inde-pendent of Reynolds number when the Mach number,the gas properties, and the velocity and Lwnlwatureprofiles do notclmnge with Reynolds number. I?or thesame conditions the boundary-layer t.hickmwsis in-versely proportional to the square root of the Rqmoldsnumber.. Separation of the laminnr boumlury layeroccurs only when the static pressure along the surfacerises in the direction of the flow.

The flow over the Munt bme of bodies and over blunttmiling edges of wings is important from drag consid-erations in supersonic flow. As a fumlamenttilapl)rozchto these problems an analytical study was made of thophenomena of laminar mixing in a compressive fluidand reported in Technical hTote1800. Detai~cdvelocit.yprofiles were computed for free-stream Mach numbersfrom Oto 5.0. The effect of various assumptions for thochange of viscosity with absolute temperature wasconsidered.

The free turbulent mixing of a supersonic jet of Machnumber 1.6has been experimenhdly investigmtcdand therewdtehave been reported in Technic-alNote 1857. Aninterferometer was used in the investigation to measure

m-- a-- . . . . . . . . . . . . ..- ”------- COMMITTEE FOR AERONAUTICS u.tiLJXlfCl NALiUNflli RDV~UKX

density and -relocity distributions through the mixingzone. Velocity distribution vm.sfound to be similar tothe distributions for incompressible jets only over thesubsonic pm-t of the mixing region.

An investiemtionwas undertaken to study certain in-terference effects arising from tunnel-wall boundariesin airfoil investigations at supersonic speeds. The re-suks of the investigation indicate that for airfoil modelsmounted from the wall of a supersonic tunnel largepressure disturbances over parts of the model can resultfrom shock--wavepropagation into the stream due to athickened tunnel-vvall boundary layer at the modellocation.

Compressive FlowsThe results of a study of the subsonic flow past an

infinitely long corrugated circular cyIinder are pre-sented in Technical Note 1850 to show the relation be-tween two-dimerisiond and three-dimensional axisym-metrical flow. A solution is obtained which containsas limiting cases both the Prandtl-Glauert correctionfor tvrodimensiona~ flow and the Gothert correction forthe flow past slender bodies of revolution. Includedde-o are velocity-correction f ormrdas for a cylinder witha single bump and for a corrugated cylinder in thepresence of walls.

In connection with the use of the hodograph methodof treating plane potential compressible flows, varioushypergeometric functions that arise m particular solu-tions of Chaply=ti’s differential equation ha-re beentabukded in Technical h’ote 1716. These tables shouldprove useful in the tabulation of other auxiliary func-tions arising in various compre~ible-flow problems.

A number of investigations have been made by se-rerdeducational institutions, under contract to the NACA,reIative to the theory of compressible flows past two-dimensionaI airfoils. Among these investigations wasa study made at Harvard University of the supercriticdflow past an NACA 0012 airfoil (TechnicaI Note 1746).Relaxation methods were employed to calculate thepressure distribution, and the results were observed toaameequalitatively quite -well with experiment. In acentract investigation by Brown University, reportedin Technical Note 1875, the application of the methodof operators to the study of two-dimensional comprts-sible flows was estended to the case of supersonic flowpatterns.

The analytictd methods that appear to be best suitedfor the treatment of two-dimensional supersonic flo-wswith detached shocks have been reviewed in Technicalh’ote 185% A short discussion of the application of themethods regarded as reliable in the transmit mnge isincluded.

Interest has increased recently in the theory andapplication of unsteady flows. Experimental measure-

ments and theoretical calculations have been made forunsteady flows in passages of constant cross-sectionalarea. The flow considered included expansion zones, -discontinuous compression fronts, temperature contactdiscontinuities, and reflections and interactions of thesequantities. Agreement of experimental pressure-timemeasurementsand discontinuityy position and configura-

,-_—

tion with the theory is very @.An extended point-by-point method has been devel-

oped and desxribed in Technical Arote1878 for the cal-c~ation of unsteady flows thro~ah tubes with variable ___cross sections containing strong shocks and large tem-perature contact discontinuities. Calculations -weremade of the flow pattern created by the bursting into avacuum of a diaphragm at the minimum section of asupersonic nozzle.

Gas DynamicsThe extreme altitudes at which sounding rockets and

missiles operate ha~e introduced a new fleld of funda-menttd rterodynamic research. At these altitudes theair must be considered as composed of individual mole-cules rather than as being a continuous medium. Newfacilitiw have been put into operation for exploring the ‘-phenomena encountered in very low density flows. Dif-hdt problems of technique have been encountered inthe design of these facilities and the greater part of theefEortto date has been concentrated on the developmentof research methods. One example of these problems isin the visualization of lowdensity flows. At very lowdensities the schlieren technique for flow visualizationbecomes impracticable or irnpossib~e. A new and prom-ising method of flow visualizdion has been investigatedand reported in Technical h’ote 1900, in which the phe-nomenon of afterglow was utilized.

A preliminary investigation of free-molecule flowabout transverse wires has been undertaken. Heat-transfer and drag measurements have shown goodagreement with free-molecuIe theory.

Theoretical research on lovvdensity flovis has alsobeen conducted during the past year. Calculations ha-rebeen made using the methods of kinetic theory of thetemperature rise of uncoded flat plates traveling athigh speeds in the upper atmosphere. These calcula-tions were reported in Technicrd h’ote 16S2. A methodwas deri~ed in Technical h’ote 1S21by mems of whichpressure measurements obtained behind an orifice on arapidly moving object may be used to determine theambient-air pressure. A comparison of the results ob-tained by this method and that which considers the gasto be a continuum shows the method based on the fluidconcept to be in error at altitudes which are attainable .with modern rockets.

An approximate method has been developed for theextension of the properties of the incompressible lami-

14 REPORT NATIONALADVISORY—---- ..-———--- .- A-A.-.—-A-CXMM1’l”ll$Et“UH AKkiUNAU”llC=

mm bounclary layer on a flat plate into the slip-flowregion, using Kctrmctn’smomentum methocl. At equiv-tdent stations on the same body at the sctmeReynoldsnumber the totttl thickness ctnd the skin friction of a.slipping bounchwy layer are less thn those of themmmctlboundary luyer. The difference between theslip and the normal boundary layer is small until slipvelocities at the wall become about one-thircI of thefree-stream velocity.

Very high supersonic wind-tunnel Mctchnumbers fortieroclymunicinvestigations me obtuined by ctccelerationof the air by means of a pressuredifference so that therandom kinetic energy of the molecules is con-rertedintokinetic energy in the wind-tufinel test section. For veryhigh Much numbers high stagnation tempercttnresctndpressures may be required which introduce effects ofvibmtioncd heat capacity aud of molecular forces ctndsize such thcttthe perfect gas la-ivand the asmmptionof constant heat capacity may no longer be sufficientlyaccurate. Errors in using the perfect gas law and theassumption of constant heat capacity have been evalu-atecl. The variation of heat capacity is accounted forb-y quaut.mnmechanical considerations and the effectsof molecular forces and moleculctrsize are accounted forby use of van der Waals’ equation.

In the operation of supersonic wind tunnels in gen-eral, the condensation of moisture in the air stream is animportmlt consideration because the formation of a con-densation shock distorts and modifies the flow andshould therefore be avoided. A study has been made ofthe limiting conditions under which a condensationshock will form.

Aerodynamic Heating and Heat TransferBecause of aerodynamic heating the opemtion of air-

craft at high speeds is dependent on the provision ofndequate insulation ancl coding systems or on keepingthe time of high-speed flight short. Cnlculation of sur-ftice tempercttures find the design of coding systemsare dependent on adequa~eheat-transfer data and 011”:1body of theory by which the dcttctmay be ccn’re]atedcmdapplication of the datti extencled. Experiments hambeen conducted during the past year to detel~nineheflt-tmnsfer coefficients at supersonic speeds. Duriug thecomse of this experimental work comparisons weremade with certain theoretical results which indicate astabiliztition of the laminar boundary layer when thedirection of the heat flow is from the bounclary luyer tothe surface.

Experimental results have indicated that heat-trans-fer theories that assumea constant surface tempercttureare in some respects inadequate. A general tl~eoryhasbeen developed by means of which temperature andvelocity profil% heat transfer, and skin friction can hecalculated for huninar boundary layers on a t-wo-clinwn-

sional or axially symmetric surface witbout prcssurogradient but with an arbitrary distribution of surfticctempemture.

A small supersonic wind tunnel designed cx~measlyfor the investigateion of ILeattransfer autl rclahxl plw-nomena has been phwed in opemtion during the lMSLyear. This tunnel is of the vctriable-clensilytype whichenables a large Reynolds number range to be obtttiucdjfind has special provisions for cmmring constant airtemperature and a low turbulence level. All investig:t-tion ]Msbeen undertaken in which teu]perulure-recoveryfactors have been measured in the laminrtr, tmnsilicmjand turbulent boundary-layer regions of :111inslllatc~iflat-plate model.

An investigation was couducted at the CaliforniaInstitute-of Technology, under centract with LIMXACA,to stuclythe flow and heat transfer in a heated turbulenkair jet. lfeasurernents were macle of t.hc tohil ptws-sure and temperature fields in a round turbulent jetwith various initial temperatures, and the rcsulls lmvobeen published in Technical NoLe1865. O~]eresult ~~its

thot the jet spreads more mpidly as its density buxmuslower than that of the surrounding medium. Ihtfa onshear stress and heat-transfer distrilmtious were ob -tained from these experiments.

SUBCOMMITTEE ON STABILITY ANDCONTROL

Longitudinal StabilityTo detemine the stutic longitudinal stability cl~ar-

acteristics of complete models with swept wings at lowspeeds, an investigation was cond~lctell ill tl~~IJ~@cY300-mpl~7- by 10-foot wind tunnel. The longitudinalstability characteristics with flaps dcflec’twl and re-tracted were obtained for mode.ls having wings with0°, 15°, 80°, and 45° of svreepforwarcl and swccpback.In ctddition, the eflect of horizontal-tail locatiul~on tholongitud@al stability characteristics of u series of wingancl tail combinations was investigated. Simihtr teslswere conducted at larger scale in the Lxnglcy 19-fod.pressure tunnel for a 42° and a 52” sweptback wing.Results of these investigations were compared withctvctilabletheoretical and empirical methods fur predict-ing longitudinal stability clmmcteristics.

Downwash ancl dynamic-pressure characteristics lm-hind various swept wings have been inwd.igatecl. Theresults, including the tierodynctrnic-furcechamct misticsof the wings, have been reported in Technical Note1703. It was f ouncl, for the range of configurcttioninvestigctted,that a low tail position provided [ho mostsatisfactory stability characteristits. The center 1incof- the wcdcewas found to be located in a higher posi-tion for the swept.forwctrdwings thtmfor the swepllmckwings,

REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 15

Other irmessigatione of W@ -wake have includedmeasurementsof both downmsh and side-washbehind a42° svreptbrtckwing and an analytical study of the wakeof a trian~@ar wing. This Iatter research has beenreported in Technical h’ote 1803. A method pre~iousl.ydeveloped -wasapplied to calculate dowrmnsh in bothvertical and horizontal planes of symmetry.

The effects of propeller operation on the static longi-tudimd stability of single-engine tractor monoplaneshave been irmstigated at the Langley Laboratory anda method has been developed for computing power-onpitching moments. The results of these studies arepresented in Technical Note 17522. The method devel-oped to compute the po~er-on pitching-moment curvesevolved from a study of results of 28 wincl-tunneI pow-ered-model in-instigations and permits predictions ofpower-on longitudid stability characteristics that arein good agreement with experimental results.

The effects of tail length and tail vohtroe on the lon-gitudinal stability characteristics of a powered modelof a propeller-dri~en lo-iv-vringsirgle-engirie airplane-wereinvestigated at the Langley Laboratory. The re-sults?presented in Technical h’ote 1766, show that thedestabilizing shift in the neutrd point caused by powereffects increaseswith increasing tail length or increasinghorizontal-tail area.

Severe diving tendencies experienced on straight-wing con-rentiomd aircraft at supercritical speeds havebeen irrrestigated at the Ames Laboratory. These div-ing tendencieshave been attributed in a large pwt to theincrease in angle of attack required to maintain a con-stant lift coefficient as the speed increaees.

Tests at the Ames Laboratory of two airplanes em-ploying different airfoil sections were conducted to de-termine the effect of airfoil modifications on the longi-tudinal stability characteristics at supercritical speecls.Contributions of the various airplane components tothe static longitudinal stability of the airplanes meredetermined.

For certain supersonic speed ranges, design studieshave indicated that a thin sharp-eclged wing -withoutsweep would ha-re better performance characteristicsthan other wi~~ mrangements. The Ames 1~-foot low-turbulence pressure wind tunnel has been used forinmstiegztion of fin airplane contiggration utilizing twing of this type at high subsonic speeds. In additionto basic studies of the wing and fueelage combination,various locations of the horizontal tail were investi-gated. The rewdts indicate that, at least for one generalarrangement, there are no erratic effects of compres-sibility on the longitudinal characteristics of the modelup to the highest Mach number irmestigatecl. In addi-tion, the effects of leading- and trailing-e~~e wing napswere imestigated to determine the maximum lift char-acteristics of the confibmration.

Lateral and Directional StabiiityLateral- and dired.ional-stability problems, like the

longituclinal-stability problems, ha~-e ~titiplied andassumed new importance with the increrwesin aircmftspeeds and the resultant changes in configurations.

Investigations of complete model cofiamrations haveincluded a lo-iv-speedstudy of the static lateral stabilitycharacteristics of a 55?0sweptback wing. This investi-gation conducted in the Langley 19-foot pressure tunnelwas undertaken to study the effects of Reynolds number,leading-edge flaps, and wing-fuselage combination Onthe Iateml stability characteristics The static androIIing stability characteristics of triangular-wingmodels ha-ring various tispectratios, airfoil sections, andvertical-iln arrangem&s ha-realso been investigated a~”the Lar@ey Laboratory. The effects of tail length and “- ‘-tail volume on the Iateral stability chamcterist ics of apowered model of a single-engine propeller-dri~en low-wing airplane hare been reported in Technical hrote1766, previously mentioned. TIIiS report shows that ‘-—-the increase in directional stability caused by powerbecomes Iarger as the ttiil length is increased. Therundts also show that the tendency toward rudder lockdecreases in the positive yaw mnge as the tail lengthincreases, but is unaffected in the negati~-e YaW range.

Calculations of lateral-stability deri-rative weremade for a group of wing plan forms suitable for su-personic flight. Technictd Notes 1700 and 1850 present ___the results for the rolling moment due to sideslip andthe yawing moment due to sideslip, respectively.

h in-restigation to determine the effects of thick- ___new on the lateral force and yawing moment of side-sIipping triangular w-ins was conducted at the Lang-ley Laboratory. This investigation was based onlinearized supersonic-flow theory and the results arepresented in Technical Note 179S. In this in-restiga- ._.tion, it -m-Lsfound that the contribution of wing thick-ness to the values of the lateml-force and yawing-moment stability derivatives is small in comparisontith the effects to be expected from ~ vertical tail.However, for some designs, the contribution of wingthickue= to the yawing-moment derivatives can be ap-preciable.

The effect of varying the yawing moment due torolIing over a tide range of values on the lateral oscil-latory stability characteristics of a typical swept-wingfighter has been investigated. The airplane loading _conditions were also varied to simulate an airphme -withand without -wing-tip fuel tanks. Results of this inves-tigation, pressnted in Technical Note 1723, show that “increasing the yawing moment due to rolling in a posi-tive direction increases the damping of the short-period -‘””oscillation. For any given v-alue of yawing momentciue to rolIing, the addition of the wing-tip tanks de-creased the damping of the short-period mode.


A theoretical investigation wus undertaken to de-velop a sinlplifiecl expression for the neutral-lateral-os-cillatory-stability boundary. The results Of this studyare reported in Technical Note 1727. The investigationshows thut, for particular combinations of the mass andaerodynamic parameters, two neutral-oscillatoryboundaries exist, correspcmdin.gto the high- and low-frequency modes of motion of the airplane. Simpletest functions were derived which, if satisfied, indicatethat these expressions may be used to approximate theneut.ral-stability boundary, The results obtained bythe simplified expression are in good agreement withthe results of more exact calculations.

A study was made of the lateral oscillatory mode ofmotion to determine a boundary whit.11d&nes satisfac-tory relationships between the period and damping ofthis mode of motion for a given criterion. This analy-sis reported in Technical Note 1859 rewdted in thedevelopment of a method which can define the relation-ship between period and damping for a given set ofrequirements. The report also presented a method bywhich curves representing a constnut rate of spiraldivergence may be constructed. The methods pre-sented in this report are applicable to both lateral- andlongitudinal-stability analyses.

The effects of various design parameters on the lat-eral-stability characteristics of a glider pulled by asingle towline were experimentzdly investigated in theLrmgley free-flight tunnel. The effects of varying effec-tive dihedral, directional stability, relative density, tow-line-attachment location, and towline length weredetermined from model flight tests. The results of thisinvestigation show that it is possible to obtain lateralstability with a single towline. An approximatetheoretical analysk wae also made and the results comp-ared with the model-flight-test results, The theorypredicted the existence of divergence and the periodsof 1atera.1oscillations with fair accuracy although thetheoretical damping values were too conservative to beof much practical value.

Rotary Stab~lty DerivativesBefore calculations of the dynamic-stability char-

acteristics of an aircraft can be made? the rotary-sta-bility derivatives of the design must be known. Therange of vah.ws of these derivatives and their relativeimportance have been greatly affected by changes inaircraft configuration. Research studies of these de-rivatives (yawing, rollingl and pitching) have beencontinued by the NACA laboratories with much of thelow-speed experimental -work being conducted by theuse of the rolling and curved-flow facilities of theLangley stability tunnel.

Rotary-derivativebility tunnel have

investigations in the Langley sta-covered pitching derivatives of

COMMI’ITEEFOR AERONAUTICS

wings, effects of airfoil section on rolling and yawingderivatives, effect of addition of wing-leading-edgeskits on the derivatives of swept and unswept wings,and rolling stability derivatives of a series of thinsvreptback wings. The results of ti)~exlwrimrmtal in-vestigation of the effect of geometric dihedrul on therolling stability derivatives me presented in TechnicalNote 1732. A c.ompmison of these datti with currenimethods of ctdcu]ntion indicates the effects of gcometuicdihedral can be predicted with ftiir accurncy.

Empirical corrections to the thwwet.icalvalues of theyawing n]oment resulting from rolling are presented inTechnical Note 1835. These corrections were developedfrom experinlental dattiand have been found to be gen-eralIy reliable over a wide range of lift codlicient.

A stability-tunnel investigation of the odditiondspanwise.wing loading caused by rolling lMSbeen re-ported in Technical Note 1839. The wings invcsti-gat~d covered a range of aspect ratio, sweep angle, andtaper ratio. These data can he used to determine thodamping-in-roll due to sideslip for wings with dihedral,It has been found that the values of the derivative ob-tained by applying the above data are more relialdothan vahws obtained by strip theory.

Several methods for predicting the damIling-in-mllof wings through the lift-coefficient- range have beeninvestigated rind me reported in Technical Note 192.4.One method, in which the damping-in-roll at zero liftcoefficient was modified only in accordance with vmia-tions in bite-span lift-curve slope, was found to bealmost as reliable ae the complete method in which allknown factors are accounted for.

An analytical investigation wms made to derive amethod for modifying existing correction factors forlifting-surface theory to account approximately furthe effects of sweep. Theee factom, report.cd in Tech-nical hTote1862, lmve hen applied to existing lifting-line theories for damping-in-roll of swept wings. ‘1’heresulting formulas are simple and cahmlateclrcsnlts arein good agreement with low-speed experimenttil data.If the G1auert-Prandtl trimsformation is used, theformulas me applicable to swept wings at s~)eedslwlowthe critical.

Analytical investigations have been mado of the ef-fects of compressibility at subsonic speeds on the sta-bility derivatives. Formulas based on semiempiricalconcepts are given in Technical h’otc 1854 for makingcompressibility corrections to the static and rotaryderivatives of wings.

To obtain damping-in-roll data at high speeds, aninvestigation employing the free-roll technique wasconducted in tl~ Langley high-speed 7- by 10-foot tun-neI. The investigation covered a series of sweptl.mck

.

REPORT NATIONALADVISORYCOMMITTEE FOR AERONAUTICS 17

wings of various aspect ratios. Data were obtained for31ach numbers up to about 0.91.

Further high-speed data on damping-in-roll &ac.teristics viere obtained on a sweptback configurationthat was twisted linearly to represent the rolling wing.Tests were made at Mach numbers between 0.6 and 1.15in the Langley high-speed 7- by 10-foot tunnel usingthe transonic-bump technique and at a Mach numberof 1.9 in the Langley 9- by K?-iich Supersonic blo-w-down tunneI. The effects on the damping-in-roll char-acteristics of thickening the trailing edge of the aileronwere also determined.

The Langley stability amdysis section has developedtheoretical values of the stability derivatives at super-sonic speeds for thin, flat>rectangular - without di-hedral. The results of th~ study are presented in Tech-nical h’ote 1706. A linearized theory xas used in thisstudy -which pre.~ts the value of the derivatives forsteady and accelerated vertict-d and longitudinal mo-tions and for steady roLling, ynwing, sideslipping, andpitching vekities, These data are limited to Machnumbers and aspect ratios greater than those for whichthe 31ach Iine from the Ieading edge of the tip sectionintersects the trailing edge of the opposite tip section.

An analysis of the stability derivatives for a seriesof svieptback -wingswith sweepback and svreepforwardof the trailing edges has been made using the pressure-distribution data presented in Technical Note 1572.The derivatives were forrmdated for a range of angleof attack, sidedip, verticaI acceleration, pitching, roll-ing, and yawing. The results of the investigation, pre-sented in ‘Technical hTote1761,are Iimited to Mach num-bers for which the wing is wholly contained between theMach cones from the lea@o and trailing edges of thecenter section of the wing.

A theoretical evacuation has ah been made of thelift and damping-in-rolI of a series of thin sweptbackwings of arbitrary taper and s-weep. This analysis ispresented in Technical Note 1860 and is based uponlinearized supersonic-flow theory. The resdts are validfor a range of supersonic speed for which the wing iswhoIIy contained bet-men the Mach cones from theleading ancl trailing edges of the center section of thewing. A series of design charts is presented whichpermits rapid estimation of the lift-curve slope anddamping-in-roll derivatives.

A preliminary experimental investigation to deter-mine the damping-in-roII of severaIrectangular and tria-ngular -wiWshas been conducted in the Langley 9-inchsupersonic tunnel.

controlsConsiderable research is being undertaken on con-

trol problems because control characteristics, both

static and dynamic, are of great importance in aircraftand miss.iIedesign.

An analytical and experimental investigation of th~eilect of plan-form changg on the lift and hinge-mo-ment characteristics of control surfaces has been madeat the Ames Laboratory m a continuation of an exten-sive control program. The systematic experimental re-sults obtained in this investigation have been comparedwith various theories for predicting Iift and hinge-moment parameters for the con-rentional and sweptlmckplan forms investigated. This comparison indicated amethod of prediction sufficient’lyaccurate for prelimi-nary design purposes.

A flight investigation was conducted on an airplaneequipped -with an ull-rnovable horizontal tail having acontrol system incorporati~~ the combination of gemedunbalancing tabs and ser-rotabs. The results of this in-vestigation are reported in Technical Note 1763. Thebasic system offered the possibility of having a constantcontrol-force gradient regrmdIes of altitude or airplanecenter-of-amvity position, but was found to be unsati+factory when rapid elevator deflections viere requiredbecause of light stick forces. Flights made vvith thesystem modi&d to increase the stick force for rapid ‘-control application (whiIe maintaining low controlforces for gradud maneu~ers), in conjunction -with anall-movable horizontal tail or a corrrentiomd elevatorlindicated that satisfactory stick-force gradients for anymaneuver -wereprovided.

As part of the lateral-control program at the AmesLaboratory, high-speed tests of lateral controls of nswept wing with fences to improve the low-speed stallingcharacteristics indicated tlmt the pnrticuIm fences in-vestigated mill have no appreciable effect on the higll-speed control characteristics.

The Iateral+ontrol characteristics of several aileroncon6gurations investigated in the 300-mph 7- by 10-foottunnel at the Langley laboratory have been reported inTechnical Note 1738. This report presents the resultsof the efiects of varying trail@edge angle and controlspan on the rolIing effectimnes, lift etkcti~enesss,andcontroI hinge moments. It vias found that, for the thin-ner trailing-e~~e anglw, theoretical methods for pre-dicting control d?ectivenees viere satisfactory. How-ever, the abmement between experiment and theory waspoor for the large trailing-edge angles. The e&ctive-ness of 20-percent-chord half-span ailerons and high-lift and stalI-control devices on three s-weptwings hasbeen investigated at high ReynoIds number in the Lang-ley 19-foot pressure tunneI. The effects of airfoil trail-ing-edge shape on aileron effectiveness at high-subsonicMach numbers have been investigated in the LangIey8-foot high-speed tunnel. The resultsof this investiga-tion are presented in Technical Note 1596.

18 REPORT NATIONALADVISORYCO~fI~EE FOR AERONAU’T~CS

Auxiliary types of lateral controls huve been investi-gatedin the Lungley 7- bylO-foot tunnel. Oneinves-ti.gtitioninchded the study of eebgnentedplug aileronsextending from the 20-percent-span station to the 80-percent-span station of a 42° sweptback wing. The seg-ments were mounted normal to the free-stream flow.The basic aileron and the aileron with several modifica-tions -werein~estigated for a range of spoiler projectionfor vmious angles of attack. The plug aileron was alsotested in conjunction with a full-span slotted flap.

The results of the investigation .of plug ailerons on nthin low-drag straight wing in conjunction with a full-span slotted flap are reported in “Technical hTote1802.The investigation, which covered the range of Machnumber from 0.13 to 0.61 indicated tlutt the plug-aileronconfiguration developed would be suitable for lateralcontrol in conjunction with full-span slotted flaps. Theeffectiveness of the plug aileron increased with increas-ing Mach number and Reynolds number, The vnriat ionof rolling moment with aileron projection was fairlylinear. The rolling effectiveness was greater with theflap deflected than with the flap retracted.

Anotier unswept wing with 15-percent-thick airfoilsections was investigated with both plug and retract ableailerons in conjunction with a full-span slotted flap.The results of this investigation are presented in Tech-nical Note 1872. The study indicates that large iu-cremee in lift can be obtuined by use of full-span slottedflaps nnd that, in a certain deflection range, the flaps canbe used to advantage as a glide-path controL It wasfound that the plug aileron was generally more effectivethan the retractable aileron, but that both were effectiveroll controls. The yawing moments produced by theailerons were generally favorable -with the flap re-tracted, becoming less favorable with increasing angleof attack or flap deflection.

To investigate the low hinge-moment characteristic?of spoilem, tests -weremade of an unswept wing withan aspect ratio of 3.

An investigation was made in the Langley two-dimen-tional lo-w-turbulence pressure tunnel to determine theeffectiveness .of n lateral-control device for a wingequipped with a full-span double-slotted flap. The rearportion of the.flap was hinged in the manner of a con-ventional Frise aileron, and the lip of the double-slottedflap acted as a slot-lip aileron. This study showed thatthe lift effectivenessof the slot-lip aileron increased withincreasing flap deflection. In general, the results in-dicate that a slot-lip aileron can be combined with atrailing-edge Frise aileron on a full-span double-slottedflap to provide satisfactory lateral-control character-istics viith large flap deflections.

The Langley low-turbulence tunnel section also in-vestigated a two-dimensional airfoil equipped with a

sealed internally balanced control surfilce in conjunc-tion with a leading tab. Ihsults of this study indicatethat the w of a leading bab will result in large incre-ments in lift effectiveness for a range of tub-fia~l&llec-tion ratio.

To permit the intelligent selection of aerodynamicbrakes, the drag characteristics of various brakes Mmeasured in flight-and in wind tunnels have been col-lected and summarized. Chdculation procedures amlgraphs l~avebeen prepared that simplify the determhm-tion of the speed-altitude-time relationship)for nirplnnesequipped with aerodynmnic brakes in vnricmsspecifiedrnaneuvm.

A wind-tumlel investigation was conducted in [hoLangley 300-mph 7- by 10-foot tunnel to determine thecharacte&tics of ailerons used as speed brakes or glidc-path controls. The tests were mnde on an N.\CA65–210wing and an hTACA 65,-215 wing equipped withfull-span slotted flaps. Several plug-aileron nnrl re-tractable-aileron configurateions were investigoted utMach numbers between 0.13 and 0.71, Tllc results ili-clicate that plug or retractable ailerons, either nlonc orin conjunction with wing flaps, are very effective asspeed brakes or glide-path controls.

The effectiveness of the horn-balanced flap in reduc-ing hinge moments at high-subsonic nnd transomcspeeds has been inwstjgated, respectively, in the IMlg-ley high-speed 7- by 10-foot tunnel and by the wing-fiow method. The investigation in the 7- by 10-foottunnel was mnde with a 45° sweptback wing wl~il~thewing-flow-method study employed a 35° swep[backwing.

The efect of-- trailing-eclge thickness on the high-subsonic and traneonic characteristics of an aileron una 42.7° mveptback wing has been investigated iu thfiLangley high-speed 7-by 10-foot tunnel.

The tr&sonic-bump twhnique has nlso been used todetermine the lateral-centrol characteristics of 30-pcv-cent-chord plain flaps of various spans. The wing uwdin this study had 450 of sweepback aml an aspec~ratioof 4. The rolling, pitchingl and lift charactwist icsattributable to control deflection were determincd.

The influence of spanwise position ~nd size of the ailwrons on the control characteristics wns investigated attransonic speeds. The investigation was made by meansof a coordhmtecl study of wind-tuunel results (transonicbump) and rewdts obtninecl with free-flight rocketmodels.

Generil investigations of the effectiveness of wingcentrole have been continued by the useof simpla rocket-propelled free-flight modek with the object of clevclop-ing controls satisfactory for flight at transcmic an(lsupersonic speeds. The data were obtained at almostfull-scale Reynolcls numbers. As part of the inve.sti- “

REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 19

~ntions, the rolling effectiveness of simple trailing-edgenilerons, in conjunction with a .~ries of viings differingin s-weepand airfoil section, was determined.

C)ne type of wing currently believed suitable forflight at supersonic speeds is the thin unsviept wing ofmoderate aspect ratio. Accordingly, a rocket-pro-pelled-model investigation of the rolling effectivenessof a typical wing of this type having outboard trailing-edge ~i]erons hl~sbeen Undertaken.

To obtain the supersonic control characteristics ofwing-body cornbinatiomq,two -wings of different planform were tested as dl-movnble surftices and as fixedsurfaces in the presence of a half fuselnge at a Machnumber of 1.9 in the Langley 9- by M-inch supersonicblow-clown tunnel. C)ne w~u had a triangular planform with 60° leading-edge sweep and the other a rec-tangular plan form modified by an Ackeret type tip.

.l hinge-moment investigation was conducted in theLangley %inch supersonic tumel to determine the feasi-bility of interconnecting Ieading- ancl trailing-edgeflmps for the purpose of reducing control hingemoments.

Experimental research on the effectiveness of con-trols at transonic and supersonic speeclshas shown thatthe thickness ratio of both airfoil and control surfacehas important effects on controI power. A study m-LS

conducted to determine the efiect of thickness ratio oncentrol effectireness. Results of this study me present-ed in Technical Sote l’iOS. The method developed em-ployed the Busemann third-order approximation fortwo-dimensional isentropic flow (-which incorporatesthe effects of thickness) with three-dimensional solu-tions found by the use of linearized theory.

Other investigations ha-re emphasized that, particu-larly at supersonic speeds, large twisting moments areimposed on a -wingby deflection of a trailing-edge con-trol. Hence, the torsional stiffness required of super-sonic wings to prerent aileron re~ersal is much greaterthan that required of subsonic wings. A study of wingtwisting moment imposed by traiIi.ng-edge ailerons onunswept and untapered winggnd the resulting -wingtwisting and accompanying lo= of rolling effectire-neas-htis been theoretically treated for the supersoniccase and the results have been reported in TechnicalNote 1769. The resuks of an analysis on tapered un-swept -i-ringsare presented in Technical Xote 1S90.

A study was made to determine the possibility of uti-lizing the principle of a sealed internal~ntrol-surfacebalance as a means of reducing control-surface hingemoments at subsonic and supersonic speeds.

Automatic ControIResearch on automatic controIs has been greatly ex-

panded—not only because of the increased interest in

the field of guided missiles but also because of the in-terest in automatic<ontrol applications to airplanes.Studies of some current and projected airplane designs ‘-indicate that their flying qualities can be improvedthrough the use of automatic devices.

As part of an in~estigation of control systems for ‘-target-seeking missiks, a study has been made in the ‘“’Langley free-flight tunnel to determine the automaticlateral stability of a flying model equipped with a gyro -stabilizing unit which applied control in response tobank and yaw. Fre~flight tests were matte with aficker-type controI system installed in the model andwith this system modified to produce a hunting controlwhich effectively ga-re proport iorml response. Theeffects of nmying the cant angle and rudder deflec-tions -were in-restigated.

The normally small-size, high-veIocity, and high-maneuwrability requirements of guided missiles neces-sitate automatic stnbilization systems possessing ex-ceedingly rapid response characteristics. The LangleyLaboratory is studying the factors limiting the responseof basic types of automatic stabilization =tems and therelevant aerodynamic characteristics of automatictd1ystabilized missiles in t-mendeavor to tichiere the neces-sary responsecharacteristics. In consequence%an analy-sis and a ground investigation of an automatic stabili-zation system viere undertaken. Thes.sstudies includeda generaI analysis of a system incorporating both clis-placement- and rate-sensitive gyoscopes. From thedata obtained, design charts have been prepared mhichpermit the rapicl determination of the stabilization “”””characteristics that may be expected from this system.

The Langley stability analysis section has made atheoretical investigation to determine the effect of auto-matic stabilization on the lateral oscillatory stability ofa hypothetical airplane at supersonic speeds. The in-vestigation included consideration of the effectivenessof an automatic piIot sensitive to a displacement ineither yaw or roll and of an automatic pilot sensitiveto either the yawing or rolling ana@ar -relocity. Thecalculations assumed an ideaIized control system with-out Iag. The rewdts of the investigation, preeented inTechnical Note 1S1S, indicated that, whereas all theautomatic pilots improved the stability of the sl~ort-period oscillations, the greatest improvement was ob-tnined for an automatic pilot sensitive to the yn~ingangular vebcity and geared to the rudder so that ruddercontrol is applied in proportion to the mqgdar velocity.

FIying QualitiesThe increases in speed of flight, mnde possible by

recent power-plant developments, have dictated rndicnlchnrgcs in aerodynamic design which, in conjunctionwith the mass characteristics of current and proposednircmf t. have necessitated extensive studies of the

20 REPORT NATIONAL ADVISORY

dynamic handling- or flying-qwdit y characteristics ofthese designs.

‘1’heeffect of variation of the aerodynamic chmacter-istics on the dynamic lnteral stability characteristics ofan airplane in flight has been investigated at the AmesLaboratory. A method of automatically varying thestatic lateral stability derivatives in flight was devisedto isoIate the efect.s of chnges in the derivatives fromthose resulting from other influences-such as air gusti-ness and piloting technique. The results of flight testsmade with the automatic equipment installed have dem-onstrated the practicabfity of the system (TechnicalNote 1788). This method of varying the aerodynamicderivatives appears to offer grent promise, both as nmeans for determining the optimum stability charac-teristics desired by pilots and also as a method forimproving the stability characteristics of existi~mairplanes.

Flight tests of an airplane having a 35° sweptbackwing have been completed. The results of the investi-gation are reported in Technical Note 1743, which pre-sente the laterid and directional stability and controlcharacteristics of the airplane with and without an8t)-percent-spnnslot and with and without a ventral fin.This flight investigation showed thtit the directionalstability of the airplane was positive in all conditionsbut was reduced tom undesirably low value at high liftcoefficients with the ventral fin removed. The pilotconsidered a slight negative dihedral effect, present atlow liftcoefficients, more objectionable than mhigh posi-tive dihedral effect present at high lift coeticients. Thelongitudinal stability with an 80-percent-span slot onthe wing and with the flaps neutral was high throughout.the speed range. With the-flapsdown, the Longitudinalstability became neutral or slightly negative near thestall. The stalling characteristics of the airplane wereconsidered good when the 80-percent-span slots wereused.

The Langley pilotks aircraft research division—using rocket-propelled models in free flight—has ob-tained extensive aerodynamic and flying-quality datafor a tailless triimguhu--wing airplane.

At present, flyingquality characteristics can be gen-erally compared with specific quantitative requirementexcept for stallwarning and the behavior of the airplanein the complete stall. In order to protide a preliminarybasis for a quantitative evaluation of the stall-warningcharacteristics of an airplane, a study has been made atthe Ames Laboratory correlating pilots’ opinions ofstall-warning properties of 16 airplanes with a numberof the quantitative factors producing the warning.The results of this study, reported in Technical Note1868, indicate the quantitative ranges over which satis-factory etall warning occurs for preliminary rollingmotion, buffeting, and rearward travel of the control


stick. It was found thut the degree of buffeting andrearward movement of the control stick consideredsatisfachry as a stall warning was iniluellced by themagnitude of the rolling velocity in the complvte d all.

SpinningAs have many of the other design factors, spinning

characteristics of aircraft have been affected by cl~ang-ing aerodynamic and mass characteristics. Investigat-ions of spinning problems have km conducted for themost pmt in the NACA free-spinning tunnel at theLangley Laboratory.

The results of an analysis of antispin fillets are prc- ‘“sented in Technical h70te1779. It was found that actionof the fillets is such as to increase the damping elk-tiveneasof the f uselage area below the fillets, thus tml-ing to prevent spin. An investigation of dorm] fins, inconjunction with this project, shows that the dorsal finsinvestiggt:ed had little effect on the spin and recoverycharacter~tics. An investigation of the effect of taillength on spin-recovery charncteriatice was completedand the results of the investigation were preseuted inTechnical Note 1’764. It was found thnt a model with along tail length had better recovery chrwactcristice thana model with a short tail length where the models hmlcomparable values of tail-damping power factor or evenwhen the damping factor for the short-ttiil model wasgreater.

The spi&ing characteristics of a twin-tail, low-wing 7personal airplane were investigated. Results d thisinvestigation (Technical Note 1801) indicated thatwhen the”rudders and ailerons were interconuec[ed fulldeflection of the controls against u spin would result insatisfactory recovery. The results also inclicato thatwhen an independent rudder-aileron system is em-ployed—with the up-aileron movement limited to a verysmall deflection and a rudder deflection which main-tained the outbomd rudder near neutral-tho modelwould be incapable of spinning.

& in previous years, spin-recovery investigationshave been conducted for a number of military-airp]anodesign configurations.

In connection with spinning studies Several emgr-gency recovery devices have been investigated. The re-sults of an investigation nmde witli. u dynamic modelhaving a reaction rocket attached to the inboard wingtip and ‘fired rearward to provide a yawing momentagainst the spin are presented in Technical Note lt3CC.Spins -wereterminated rapidly, indicating tll~tta prop-erly selected jet-reaction device is an effective methodof spin recovery in an emergency.

Results of testsof spin-recovery parachutes htivebeenreported in Technical h~ote1869. These data indicntothat parachute-opening charaetwistics are improved byincreasing relative shroud-line length, tacking of Woat-

REPORT NATIONAL ADVL90BY

ing”’ hem ties to prevent pulling out under load, orproviding a strip of low-porosity fabric around the”canopy in the area immediately above the hem line.These design idtemtions did not affect the drag charac-teristics of the parachutes appreciably, although thestrip of low-porosity f abric just above the ~em Iine hadw s~uht adverse effect on their stability characteristics.It is indicated that for a given parachute increased air-speeds generally impair opening characteristics, de-crease the drag coefficient, and improve stabiIity.

~ method for estimating the diameter of the spin-recovery parachute has been devised. Correlation withtest data indicates that the method will provide satis-factory estimations of the minimum-size parachute re-quired. ~ method for determining approximate shockload associated with rapid opening of the parachute hasalso been developed.

Speci’fic Design Studies

In addition to the many generalized studies of sta-bility and control undertaken at the laboratories, SpS-cfic studies of component parts or complete con6gura-tions of currently interesting designs were made. Pilot-less and piloted aircraft and special research designshave been included in these studies, Theee invest@-tions hare provided important design information, aswell as useful research data.

The 11’ACA, in cooperation viith the United States.lir Force and the Bureau of Aeronautics, Departmentof the h’avy, continued tra~onic-fight in~est@ionsof full-scale aircraft at the lluroc Air Force Base. TheX–1 and D–55S–H. airplanes were flown repeatedly atsupersonic speeds, rmd a Iarge number of successfulflights were made with otler research airpIanes. Theseinwstigutions ha-reextended the knovrkdge of phenom-ena encountered in the high-subsotic, transofic? andIow-supersonic flight regimes and have contributed tothe correlation of aerodynamic data obtained throughthe use of other research techniques.

During the past year, the longitudinal stability ofthe D-55 S-1 airplane in accelerated ~ht has been in-vestigated nncl the buffet boundary has been determined.The dynamic lateral stability and the approach andlanding characteristics of the airplane have also rmder-gone instigation.

IIeasurement of the geneml aerodynamic chamcter-istics and aileron electiveness of the .X–1 airplane wascent inued. Data have also been obtained for rudder-flxed aileron roIIs, during glides, at high 3fach num-bers Some of the longitudinal stability and controlcharacteristics of the .X-1 airplane configuration weredetermined also by the frefall-model technique. Inthis investigation, the elevator was automatically con-trolled so that it produced a constant value of norn~alnccelerat ion thro~ohout the speed range of the drop.


As one phase of the research-airplane program, aseries of wind-tunnel tests was made of a scale modelof a high-speed airpIane to determine the static lateraland longitu&al stability characteristics at Iow- andhigh-subsonic Mach numbem. The study includedmeasurements of the effectiveness of wing flaw hori-zonta~tail, and ailerons as welI as mwsurements of the

--

forces and moments acting on wing-tip ram jets andauxiliary fuel tanks. Pressure distributions on the -wing and fuseIage were also obtained.

~ lovr-speed investigation was made in the Langley -”300-mph 7- by 10-foot tunnel of a scale model of anairplane having a 38.7° s-iveptback wing and conven-tional tail surfaces. The investigation-the readts of-which are presented in Technical A’ote lT49-was con-ducted with se~eml wing-leading-edge and. tail con&l-rations to determine the low-speed stability and controlcharacteristics. ~ guod correlation of wing-fuselageinterfertmce effect on effective dihedral was obtainedbetweeu data for the test model and other &nerican andGerman data.

‘Using ro&et-propeIIed modeIs in free flight, thepiIotless aircmft research division of the LangIey Labo- ----ratory conducted tests on a supersmic airplane con-fi=gration at speeds varying from subsmic to low super-sonic. These tests were made to determine the genemlaerodynamic characteristics and stability and controlcharacteristics of the airplane contlguration. A simi-lar model was tested by the wing-flow method at theLangley Laboratory to determine the longitudinal sta-bility and control characteristics at tmnsonic speeds.

& investigation of a semispn model of a tailless-airplane design was conducted in the high-speed 7- by10-foot wind tunnel at the LangIey Laboratory. Theresults were compared with the results of sting-mountedcomplete-model tests and the results of semispan-rnodeltests (-wing-flow method), thus pro-riding a check on thevarious techniques.

An analysis of the estimated flying qualities of a tail-1sss airplane, having a 35° wveptback wing, over ahigh-subsonic speed range has been made at the Lang-ley Laboratory. This laboratory has also investigatedthe stability and controI chamcteristics of a scale modelof a taillees glider hawing a 43° sweptback wing.

The Langley Laboratory has conducted in-restiga-tions on sewraI unconventional aircraft configurations.One investigation was concerned with the flight char-acteristics of a canard con6guration (tail first) at _.transonic and supersonic speeds. Another investiga-tion was concerned with the determination of the staticlongitudinal stability and control characteristics of amodel of a convertible-type airplane with rigid andarticulated propellers.

Investigations of triangular wings ha~e shown this .._particular plan form to have certain aerodynamic ad-

22 REPORT NATIONALAD1’ISORY

vtintages. Studies of the dynamic lateral stabilitycharacteristics of a specific nirplane configuration em-ploying a triangular wing ~- made. These studiesincluded determination of the neutrnl-lateral-oscilla-tory-stability boundary, the period and time to dampto one-half amplitude of the lateml osciIIation, and thetime to damp to one-hnlf amplitude for the spiral modefor a range of lift coetlicient and nltitude.

SUBCOMMITTEE ON INTERNAL FLOW

?lflicient hmdling of the large -volumes of air re-quired by aircraft employing turboprop, turbojet, ranl-jet, or related propulsion systems is a prime considera-tion in eficient aircraft des+gn, To aicl in maintainingtin effective internal-flow research program, the Sub-committee on Internal Flow has conatmtly reviewedthe problems in this field. Some of the recent activityof the laboratories of the NACA and pellinent resultsof investigations, in the field of internal flow, follow.

Air InletslVork has been under way at both the Langley and

Ames Laboratories to. supply clesign data for nir in-takes suitable for the turbine-propeller type of po-iver-plant installation. In recent studies of cowl inlets withpropellers operating, the eflects of propeller-shankdesign on irdet-pressure recovery were investigated.In connection with this study a method was developedwhereby the flow fields of cowling and cowling-spinnercombinations can be calculated from surface pressuredistributions.

The Ames Laboratory has studied the effects of apropelIer on the characteristics of submerged inlets fora typical gas-turbine-powered airplane. With the pro-peller providing no thrust, there was a 10SSof ram-pressure recovery that varied vviththe blade angle andangle of attack, but was relatively unaffected by varia-tions of inlet-velocity ratio. & the thrust coefficientwas increased? the ram-recovery ratio increased andeventually exceeded that obtained with the propellerremo~ed.

Research on air inlets at high-s~lbsonic and transonicspeeds has been receiving greater emphasis because ofthe growing need for such datti, The Lnngley Labora-tory recently completed tests of a selected group ofISACA. l-series nose Mets operating in the transonicspeed range. It was the purpose of this project to snowthe degree to which critical Mach number can be esti-mated from lo-iv-speedpressure distribution.

In the supersonic range, theoretical and experimentalinvestigationslave been macle of. conical inlets havingcentral bodies. Inlet configurations giving the bestrelation between pressure recovery and external dragwere determined for the range of conditions investi-gated. Data obtained f ro~n this im-estimation have


made it possible to devise a method for the estimntiouof the drag ahd pressure recovery.

Bemuse of tile intereskof designers in lmding-edgeair inlets on swept wings, the Ames Laboratory hasinvestigated this type of inlet for a wide rango of inlet,vekwity. Pressure-distribution, rmn-prcssurc-rccov-ery, and wake-survey datu have km obtained. Theducted section of the wing was designed by the applica-tion of an analytical method deve]opcd for leading-edge inlets on unswept wings. It was found from thosetests that thin duct lips were sueceptible to Iami mrseparation near tl~ leading edge, resuIting in high sec-tion drag.

The installation of electronic de-rices, armament,ancl other equipment in nose sections of aircraft limitsthe use of simple nose inlets. llus, side inlets are ofconsiderable intcrest. In some instmccs side-inlet in-stallations permit atttiinmentof low duct kscs becauseof the short duct lengths used. Ill order to realize fur-ther gains in inlet-cliffuser-duct efficiency, th~ AmesLaboratory has been working on a submerged inlet withn cascade of airfoils to diffuse and at the same time turnthe nir into the engine settling chmber, The resultsindicate that at least for large air deflections the cascndcinlet has relatively good pressure recovery.

Boundiwy-layer control hns been anothcr mmms ofincreasing the performance of air inlets. Work at. [heAmes Laboratory on submerged side inlets with bound-ary-layer control has shown that an improvernwlt inram-pressure recovery can be realized, espccially atlow mass-flow ratios. It tdeo appears that.the sktbilitycharacteristics of submerged twin inlets can bo im-proved by the use of lxmnclary-lnyer centrol. Thequantity of bounclary layer removed ancl thus the cx-pencliture of power for this removal were found to bcrelatively small.

Other submerged-inlet configurateions invest.igntwlwere a pmxdlel-witIed inlet and al] inlet with divergingramp mulls. These stucliesindicate that diverging theinlet ramp walls effectively extends the satisfactory op-erating limit of the submerged inlet to higher 31adInumbers. The superiority of the divergent- wallecl in-let is attributed to the ramp bountlmy-layer character-istics aesociatecl with this configuration. The mos~ .promising of-the submerged-inlet configurations arcbeing studied at trnnsonic speeds.

A study at large scale of submerged side inlets hascontinued in the 40- by 80-foot wind tunnel at the AmesLaboratory. The effects of sideslip on the eillciency ofboth single- and twin-inlet systems and the effects ofmass-flow ratio on the stability of twin-inlet syshwshave been investigated, It was found that the rccovesycharacteristics of either the single or twin inlet are rela-tively insensitive to small angles of siileslip, A wcll-


defined region of unstable flow and of re~ersedflow wasencountered with the tmin-inlet system at low mass-flow ratios. Studies to explain and clarify the cause ofthis flow instability and re~ersal hn-re also been com-pleted.

Continued research in the Ames 8- by 8-inch super-sonic mind tunnel has shown that, at Mach numbers lessthan 1.S,extended side inlets can attain a total preesnrerecovery comparable with that of a nose inlet.

Ducts and Duct ElementsAir-handling components other than the air inlet

have received detailed consideration. Two annular dif-fusers of diflermt conical expansion angles but con-stant outer diameters hare been in-restigated -withrotat-ing flow behind an axial fan at the Langley Laboratory.The performance characteristics of the diffusers meredetermined and the rotational-kinetic-energy effects onthe over-ail energy transformation were obser-ied o-rera range of inlet Mach number and angle of flow. Theseresults have been reported and show that a -widerangeof flow distribution is encountered as a resuIt of changesin operating conditions. The o-rer-all performance ofan SOdiffuser was shown to be appreciably better thanthat of a 16° diffuser under comparable conditionsSharp reductions in efficiency were recorded in both dif-fusers at the maximum -raluesof stream rotation.

Further research on ducts in the 8- by S-inch super-sonic mind tunneI at the hes Laboratory has shownthat in supersonic flight, -wherethe flow -velocitiesin airinlets are relati~ely high, the design of the subsonic dif-fuser behind the inlet requires particular care. A ductshape that minimizes the adverse pressure gradient im-posed upon the boundary layer produces a considerableimprovement in pressure reco-rery.

A study of screens in -wide-angle diffusers was madeat the National Bureau of Standards under an X-KMcontract to determine the effect of screens on flow sepa-ration and flow turbtience. This study reported inTechnical Note 1610shows that screenscan prevent sep-aration and restore separated flow. The mechanism ofthe flow as affected by the screens is also discussed inthe report.

Results of a study of friction coefficients in the inletlength of smooth round tubes conducted at the Massa-chusetts Institute of Technology under an h’ACA con-tract are reported in Technical fiTote1785. The experi-mental redts of this study are compared with theory.As a result of the study, an approximate method w=de~eloped for predicting the discharge coefficient ofrounded-entrance flow nozzks.

Jet Exit StudiesStudies of exit influences on both the internal and

external air-flow characteristics of aircraft are assum-ing greaterimpofiance with increasing flight speeds.

COWTTEE FOR AERONAUTICS 23

An investigation is being made at the Ames Labora-tory of the effect of various asymmetrical exits on the

.—

direction of the jet. reaction. The jet beiug studied is-sues from the end of a streandined bocly. For the in-w3stigationjet-exit, cut-off angle was varied from 0° to75°, the jet-exit velocity ratio (jet velocity to free-stream RIocit y) was varied f rom Oto 4.0, and the n~axi-mum Mach number of the jet at the exit was 0.80. Thein-restigation indicated that angularity of the pipe cut-off does not affect the direction of the jet reaction, butmay have appreciable effects on the stability character-istics of an airplane if the mixing area of the jet in-fluences the air flow about the controki or stabilizingsurfaces.

Air ejectors for pumping cooling air for jet enginesare coming into general use. Ejector stuclieshave con-tinued at the Lewis Laboratory with emphasis on theoryof operation and performance. An investigation of theeffect of operating temperature on ejector-pump per-formance and an analysis of ejector thrust by integra-tion of surface pressureshave been completed.

SUBC03L711’ITEE ON PROPELLERS FORAIRCILAET

During the past year, research efforts have been ex-tended to impro~e the performance of propellers athigh speeds. To this end, considerable effort has beenexpended in conducting high-speed, wind-tunnel inves-tigations of propeller problems

B1ade SectionsAn investigation was made to evaluate the effect of

blade-section thiclmess ratio on the aerodynamic char-acteristics of a propeller. The instigation consistedof wind-tunnel stucliesof five related propelle~ havinga wide range of section thickness ratio.

High-Speed PropeIIersPreliminary studies have been made of the effects on

propeller performance of the utilization of blades em-bodying sweep in the blade plan form. A propelleroriginally designed for f3ight resermchwas imestigatedin a high-speed wind tunneL The results provide abackground of information on the operation of sweptpropellers at subcritical conditions-

It has been found that the introduction of sweep ina propeller blade introduces unusual md complex vari-ations in the distribution of stress in the blade. As aresult, special methods ha~e been developed to deter-mine and reduce the stressesand deflections in the bladesof swept propellers.

&t investigation has been made in which the staticthrust characteristics of four related propellers differ-ing in camber and blade -width were determined. Theresults obtained are useful in providing basic informa-tion on the design compromises necesary to obtain ‘--

24 REPORT NATIONALADVISORYCOMMITTEE FOR AERONAUTICS

~dequate performance for satisfactory t~ke-offcharacteristics.

An investigation has been made in flight to providebasic information on optimum propeller-Made loadingsfor both the climb and high-speed conditions. Theresultsobtnined, which were reported in Technical Note1784, indicate the large increase in power londingswhich is required to obtain maximum efficiency athigh speeds as well as the design compromises betweenthe climb and high-speed conditions. In the climb con-dition, the increase in blade loading associated with areduction in number of blades from three to two led tomarked reductions in propeller efficiency, whereas forthe high-speed, level-flight con~ltion, even greater 10ZSCSin propelIer efficiency -were associated with faihme toobtain sufficiently high blade londings to obtain mnxi-mum efficiency even with the reduced number of blades.

A contract investigation vrnsconducted by StanfordUniversity to determine the influence of blade-widthdistribution on propeller performance characteristics.Force and wake-survey data were obttiinedfor a numberof three-blade moclel propellers of equal activity factornnd dissimilar blade plan forms. Although the differ-ences in the efficiency envelopes for the various propel-lers were small, it was found that blndes tapered frombroad roots to narrow tips were more dlicient thanblades of relatively uniform width -whenoperating atpower coetlicientsgreater than 0.1 and at advance ratiosless than those for maximum efficiency. The resultsof the investigation are reported in Technical Note 1834.

Vil.mationand F1utterof PropellersAs a result of serious vibrational difficulties arising

from the operation of large propellers in nonuniformflow fields and under conditions of pitch and yaw, acomprehensive program was initiated to determinemethods of calculating the stressesinvolved as well asmeans of alleviating these stresses. Investigations onthis problem are under way at both the Langley andAmes Laboratories. The applicability of existing pro-peller theory and the theory of oscillating airfoils tothe problem has been studied.

SUBCOMMI’IT’EE ON HELICOPTERS

In order to provide nnd interpret fundamental infor-mation on the fuctors which affect the flying qualitie~performance, and reliability of helicopters, the NACAhas enlarged and intensified its resenrch in this field.In addition to theoretical studies,experimental investi-gations have been carried out on full-scale and emall-scale models in fligh~ in wind tunnels, and on the Lmlg-ley helicopter test tower:

Rotor-BIade SectionsFive NAC!A airfoil sections intended for use on heli-

copter rotor blades were designed and tested in the

Langley lwo-dimensiorml low-turbulence pressure tun-nel. These airfoils have thicknesses vnryiug from 9to 15 percent of the chord and design lift cocmcicntsfrom three-tenths to seven-tenths. Theoretical pressuredistributions, together with measured values of the two-dimensional aerodynamic chnracteristice over a rangoof Reynolds number, were obtained for each airbil.In nddition, the eflects of surfnce concMion on the :~ir-foil characteristics were determined, The results ofthe investigation, which are presented in Technical Note1922, N-tie nnalyzed to demonstrate the effects of varia-tions iu thickness nnd camber on the pertincn~ aero-dynamic chmwcteristics. Theoretical calcnlntions fordifferent flight-conditions are included to hdicate therelative performance of sample rotors employing thediffered airfoils. Thase calculations show thnt thenew mirfoilsare inferior in performance, for most. flightconditions, to the NACA 8-H-12 airfoil wction de--veloped in n previous investigation.

Rotor Performance

An investigation was made on the Langley helicoptertest tower to determine the effects of wind vchwity onrotor performance. This information was needed toenable correlation of data obtained under various windconditions and on clifferent rotors. The results of theinvestigation, reported in Technical h’oto 1M8, were inessential ngreement with simple momentum theory-which indicates that rotor performance incremcs wi~hincreases in airspeecl above zero. & an examplel itwas found that for a typical helicopter the power re-quired to produce a given amount of thrllst, was 1.7lwu-cent le~. in a U5-mile-pcr-hour wind than undvr zerowind conditions. It was also found that the effects ofwind velocity on ~wrformance were virtually indclmd-ent of blade load distribution.

An analysis of the stedy autorotative vertical descentof a helicopter wasmade by Princeton University uuderNACA sponsorship. The effects of both constant tindvariable induced velocity over the rotor (Usk were &-tern~ined and the results reported in Tkchuicnl hrotc1906. 1%was found that, although tho wssump[ion ofconstant induced velocity causes considerable error iuthe load distribution along the blade, the rotor speedand rate of descent for small angles of blade pitch aronegligibly affected. For high angles of pitch whereblade strollingis importtint the errors in theoreticallycomputed blade load distributions may be expected tobe sutlicientto CNW disagreement with experiment. Aconsideration of the forces of autorotution indicntcd thatfor small values of blade pitch these forces WW he nde-quate for autorotation, and blade stalling can be negl-ected. At the higher values of blacle pitch, however,the possibility of blade stalling resulting from anupward gust is increased.

REPORT NATIONAL ADVISORY COklXiITTEE FOR AERONAUTICS

An analytical study has been made by PrincetonUhivemity of the motions of the helicopter in the tran-sition range from ho~ering flight with po-wer on tosteady vertical autorotative descent following a powerfailure. The effects of hinging the blades, of blademoment of inertia? and of rate of pitch reduction afterpower failure were considered. The results of thestudy, -which were reported in Technical Arote 1907,indicate that the effect of blade flapping is negligibleinsofar m the estabtient of steady autorotation isconcerned. It was also found that in order to avoid ex-~-ive blade staIling during the transition, blade mo-ment of inellia should be large and blade pitch shouldbe reduced as rapidly as possible after povier failure.

Stability and ControI

.% part of an investigation to establish satisfactoryhelicopter flying-qualities requirements and to deter-mine means of satisfying these requirements, the flying-qualities problems of current helicopters as observedduring flight -were collected and are discussed in Tech-nical ~lfote l’i99. This paper contains information onthe fl@g qualities of helicoptem obtained from per-formance testing, experience with various helicoptertypes, and knowledge of foreign work in this field. Itwas found that the principal problems of current heli-copters are: Instability -withangle of attack in forvvardflight; control sensitivity in forward flight, particularlyfor the smaller helicopters; and control forces followi-ng control movements during maneuvers. Some dis-cussion is gi-ren of suggested remedies for theseproblems.

To aicl in establishing criterions for acceptable heli-copter stabiIity characteristics? ffight tests were con-ducted on a small single-rotor helicopter possessingstick-fixed longitudinal characteristics -whichwere con-sidered satisfactory by the test pilot. Time historiesof longitudinal mzmeuvers mm obtained for correla-tion with the test pilot’s pereonal observations.

Vibrstion

The dynamic response of a helicopter rotor to oscil-latory pitch and throttle morements -wasin-restigatedon the Langley helicopter test tower to determine thenatural frequencies of the drag-angle motion and thedamping required to prewmt excessive drag-angle oscil-lation respcmse. Both q-remetrical oscillations, in whichall of the blades lag and advance together, and unsym-metrical o.~ations? in -which the blades are out ofphase with each other, were studied. The results, -whichwere reported in Technical h’ote 1888~showed that,whereas the frequency of the symmetrical drag-hingeoscillations -wasinfluenced by the engine and gearboxinertias and rotor-shaft torsional stiffness, the fre-quency of the unsymmetrical oscillatione -wasaffected

primarily by the rotor-pylon bending stiffness. Thw.eresults were ahovm to be in agreement with predictedvahs and indicated that. care should be exercised toinsure the absence in the helicopter of regular dis-turbing forces, such as a hunting pitch and throttlegovernor or hunting automatic pilot, with frequenciesnear those of the resonant condition.

A contract investigation -wascarried out by the Poly-technic Institute of BrookIyn in which a theoreticalstudy was made of the dynamic properties of helicopterrotor-blade systems. The study dedt with the appli-cation of the theory of small oscillations about a steadystate of motion to a representative blade system hingedto a driving hub. The study corered the derivation ofthe angles of zdtack of the inflow, of the blade-positionvariables-pitch, flapping, and laggtig~d of theaerodynamic inertia forces acting on hinged blades inboth hover~ and translational flight. Mao includedwere the development and solution of the equilibriumconditions of the blade system and the development ofthe frequency, stability, and damping properties ofhinged blades in both hovering and trandational tlight.Four combinations of relative con.ckraintconditions be-tween angles of pitch, flapping, and Iag=tig were inves-tigated. The results are reported in Technical Note1430.

SUBCOMMITTEE ON SEAPLANES

P1aning-TaiI HuUeHy&odynamic research on the planing-tail type of

hull has been continued in Langley tank No. 2 withforms representing the extreme in aerodynamic refine-ment for improvement of flight performanc~” Theserefinements indicate the extent of the hydrodynamicpenalties to be paid for the compromises made to achieve

low drag, but at the same time demonstrate the prac-ticability of such forms for application to advanced sea-plane designs. With the point of view adopted in thoresearch toward over-cdl improvements in hull form,special techniques were necessarily developed in thetank for adequate e~aluation of thehydrodymunic quali-ties of interest. Parallel investigations of refined plan-ing-tail hulls were abm conducted in the Langley 300-mph 7- by 10-foot tunnel to indicate the aerodynamicgains that might be achieved with this type of hull.

Length-Beam Ratio

An in-restigation of the eflects of hull length-beamratio on hydrodynamic characteristics in waves has beenmade in Langley tank A’o. 1, and the resnltsare reportedin Teehnical h70te1782. It is concluded that when theproduct of ]ength squared times beam is held constant,as -would -rery nearly be the case for interchangeablehulls on a given seaplane, the motions in trim and rimand the matimum probable vertical accelerations in


waves are substantially reduced asthe length-beam ratiois increased. The maximum probable angular accelerti-tions on the other hand are increased until extremelength-beam ratios are reached because of the increasein hull length associated with decrease in beam for aspecific design.

The research to date is believed to establish broadlythe upper limit from the standpoint of hydrodynamiccharacteristics beyond which DO further over-all im-provements may be expected from increase in hull fine-ness ratio alone.

Similar tank investigations of detailed mochficationsof the form of a hull having a high length-beam ratioare reported in Technical Notes .1828and 1853. Fore-bocly warp (progressive increase~ dead rise f rorn stepto bow) and incmaw in afterbody lenati are shown tohave marked favorable influences on behavior in roughwater. Forebody warp greatly improved spray andoverload capacity -whileincreased afterbody length hada smaller adverse effect on thesequalities. Other hydro-dynamic characteristics of interest were relatively un-affected by the modifications.

The effects of combining the modifications are re-ported in Technical Note 1980. In general, the deckof the sepnrate changes were additive to a certain cle-gree resulting in a particularly promising hull form,with a high length-beam ratio, for open-sea operations.Inferior bow-spray characteristics associated with thelengthened afterbody alone were more than compen-

COMMI’PTEE FOR AERONAUTICS

PROPULSION

‘With the emphasis on higher speeds nnd on increasedaltitudes of operation, the objectives of propulsion re-seurch are to obtnin a mnximum of thrust f or a mini-mum of engine froutal aren, engine weight, fuel con-sumption, ancl rmmufa.cturing effort. Consiclerrd.ionnm.t be given to each of these points and a suitublebalance obtained. & pointed out in the previous wl-nual report, the l?AC-A research effort must providescientific information applicable to at least five typesof flight-propulsion engines-f or high-speed flight, theturbojet, the ram--jet, and the rocket; and for lowerf@]lt speeds, the turb~propeller and the compoundengine.

NACA efforts in this field have been assisteclby theCommittee on Power Plants for Aircraf t and its sevensubcommittees. Most of the research discussed in thissection has been couducted at the Lewis Flight Propul-sion Laboratory with additional assistanceprovided bythe National Bureau of Standnrds and by educationalnnd nonprofit institutions under contract to the NACA.

As a means of bringing the findings of the NACA tothe aircraft and related industries with a minimum of

sated for by the improvements in lhis quality gaiuedviith the warped forebody.

The aerodynamic investigateion of hull length-beamratio in the Langley 300-mph 7- by 10-foot tunnel hasbeen wiended to -rery high ratios. The additional cf -f ects of the extreme ratios (of limited usefulness froma practical design point of view) on the aerodynamiccharticterietimwere found to be small.

High.Speed HydrodynamicsThe long-range program of hydrodynamic resmrch

on methods of water-basing high-sped aircraft hits

been continued. The possibilities of various high-slmdconfiawiations and auxiliary devices for usc i~1writeroperation have been evalllated and the fuudm&talcharacteristics.of promising hydrodynamic liftiug elc-rnentshm-e been studied in Langley tank NTO.f?.

SPECIAL SUBCOMMITTEE ON THE UPPERATMOSPHERE

The Special Subcommittee on the Upper Atmospherehas continued the col.lectioll of data fur use in definingmore accurately the physical chamcteristicsof the ulq]cratmosphere. Efforts are also continuing to improveinstruments and techniques for measuring the physicalproperties of the atmosphere to altitudes of LIWorderof 400,000feet. When sufficientdata me available fromsoundings by various rocket vehicles, it will bo possibleto modify and standardize the existing tenttitiveuppcr-atmosphere tables published in Technicnl fiTotc 11200.

RESEARCH

delay, conferences on sptyific phws of propulsion re-search have been held at.the Lewis Laboratory in thepast year. At these conferences significant NACit rc-eearch results were presented on hn%ojet-engine thrus~augmentation and on aircraft power-ldant centrols.

In achieving a greater thrust per unit Ii.onhil arenthe aerodynamic aspects of flight-propulsion uesmrchhave assumed increased proportions and a need for fur-ther aerodynamic studies of propulsion problems is ap-parent. In order to obtain increased thrust per unitengine weight the resenrch approach vnries with thetype of power plant, and for turbojet engines emphasisis being placed on components of greatly improved per-formance and decreased size, such as supersonic com-pressors. To obtain increased thrust per unit of fuelconsumed an increase in the pressure ratio and operat-ing temperature of gas-turbine-typo engines is indi-cated. Effort is also being placed cm possible simplifi-cation of the shapes of components of gas-turbine-typopower plants in order to reduce the manufacturing ef-fort required. The ram-jet and the rocket power plantiare inherently suitable for high-speed flight as their

REPORT ISATIONAL ADTXXJRY

elements arecdready reilucedto a minimum of frontalmea and weight, and emphasis is placed on obtainingimproved performance.

With a major share of research effort behg de~otedto the gas-turbine type of power plant, considerable m-search information on such power plants has been madeavtiilable during the past year. Progress is behg madein obtaining increased endurance life for gas-turbineparts at current operating temperatures. As progresscontinues it may be possible to alleviate the demand forscarce alloying elements for the heat-resisting parts ofgas turbines. Once satisfactory endurance life is ob-tained it may be possible to commence utlizing mate-riaIs which mill be less expensive cmd easier to handlein manufacturing processes. With the application ofturbine cooling it may be that marked improvement inaircraft gas-turbine performance may be obtainedthrough the use of higher cycle temperatures and pres-sure ratios. Substantial progress has also been madein providing a fuel for use in aircraft gas turbines -whichwill be relatively easy to mcmufacture because of theready availabilityy of its constituents and the absence ofany knock-rating requirements.

The ram jet is the type of power phmt that shows mostpromise of supplying at reasonable efficiencies the tre-mendous power nec~cary to drive aircraft in the atmos-phere at extremely high speeds. The Lewis 8- by 6-footsupersonic wind tunnel that permits study of the aero-dynamic and combustion characteristics of turbojet orram-jet en@ms up to a Mach number of 2.0 has beenplacecl in operation during the past year. The researchprogram for this facility will supply greatly neededfundamental data on the design of power plants suitablefor super-soniciligh~

COMNIITTEE ON POWER PLANTS FOR. AIRCRAFI’

Engine Performance and OperationAn investigation of the altitude-performance char-

acteristics of a centrifugal-compressor-type turbojetengine has been completed. The resLdtsindicated thatunder standarcl atmospheric conditions best thrust perpound of fuel is obtained at the tropopause. Attemptswere made to predict performance by conventiomd ~-n-eralization procedures and it was found that these pro-cedures were not applicable to these engines abcme20.000 feet because of a chana~ in compressor perform-ance with decreas~~ Re~olds number.

.In investigation has been made of the aItitude per-formance of two axicd-flow turbojet engines. These in-wstigat ions protided clata on engine and componentperformance for altitudes up to 50,000 feet and flightMach numbers up to and exceeding the speed of sound.


The data have been analyzed to show the performanceof each of the major components of the engine. Thecombustion characteristics and blow-out limits were ofparticular interest.

A ram-jet engine was investigated at sinudated alti-tudes to determine an efficient combination of flameholder and fueL A series of flame holders vras investi-gated using se-reral different fuels. The results indi-cated the relative combustion efficiencies obtained withthe different fuels, as -wellas the effects of flame-holderconilgurntion on combustion temperatures, combustionefficiencies, and operable mnge of fuel-air ratio. Sev-

--——

eral flame holders and fuel-spray nozzles have been in-vestigateed in experimental captive flight tests ~~ing arectangrdar ram jet -which was integral with a sub- —sonic wing section. Because the combustion process in

--..-.

a ram-jet engine may affect the elllcienciesof the inletsand hence the net thrust obtainable, an imwstigation ofthe interaction between the combustion process and air _inlet was made,

An experimental irmestigation ~as conducted to de-termine the improvement in the performance of a re-

—

ciprocating engine readting from compounding with aned~anst-gas blow-down turbine. A I%cylinderj liquid-cooled, compound reciprocating engine was imrestigatedover a range of engine and turbine operating conditions.The data obtnined make it possible to predict the effect “”-”of independent engine and turbine ~ariables on turbinepovier output. For comparison, the performances of five .compcmnclreciprocating-engine power plants hare hencalculated. These consisted of a 12-cylinder, liquid-cooled engine compounded with (1) a blow-down tur-bine, (9) a blow-down and stendy-flow turbine in series,(3) all-geared supercharging, (4) turbosupercharging,and (5) a steady-flow turbine (Technical Note 1735).

Cooling characteristics of two different types of uml-ticylinder, liquid-cooled, reciprocating engine were de-termined and the cylinder-head temperature and cool-ant heat rejections correlated with the primary enginennd coolant variables. This corrdat ion is similar tothat previously de~eloped from anal@s of the coolingprocesses involwd in a single-cylinder, liquid-cooledenagineand permits the prediction of both the cylincler-head temperature and the coolant heat rejection for &wide range of operating conditions

SUBCONL}IITTEE ON MIWRU?P FUELS

Availability of FuelsTurbojet engines in the United States hare been de-

veloped to operate with either kerosene or high-octanegasoline. Consideration by the miIitary services andthe ATACA Subcommittee on Aircraft Fuels indicatedthat in case of a national emergency such fuels wouldnot be available in sufficient quantity for an air force

28 REPORT NATIONAL

with a large number of turbojet aircraft. A

ADVISORY

tentativespecification -ivasdmftecl that IVOUMinclude about,one-half the refined products from a barrel of crude oil andthis fuel was subsequently designated AN-I?-58 by themilitary services. The Lewis Laboratory evaluated theperformtince of this new fuel in current-productionturbojet engines.

A compmison of the performance of AN-F-58 fuelwith the fuel currently specified for the particular en-gine was macle in two rdtitucle test chambers, in thealtit.uclewind tunnel, and in flight, for a wide range ofsimulated nhitucle and flight Mach number. Tile en.gine investigated in one altitude test chamber wasequipped with a centrifugal compressor and tubularcmnbustors designed for a kerosene-type fuel. The en-gine investigated in the second altitude test chamberwas equippeclwith an axial-flow compressor and an an-nular combustor designed for gasoline-type fuel. Thealtitude-wind-tunnel investigation was made on an en-gine quipped with an Rxial-ffow compressor and tubu-lm combusto~ designed for a kerosene-type fuel. Theflight investigation vms conducted with aq engine in-corporating an axial-flow compressor and tubular corn-bustors designed for kerosene-type fuel. These full-scale engine investigations included a determination ofengine thrust, specific fuel consumption, combustion ef -ficiency, blow-out limits, ignition characteristics, andcarbon cleposition for both AN-F-58 and the currentfuel specified for the particular engine. The results ofthe investigation showed that the use of AN–F–58 fuelresulted in performance equal in practically every re-spect to that with the standard fuel.

Effect of FueI Characteristics on Turbojet-EnginePerformance

The effect of fueI variables on the starting of turbojetcombustors is under investigation. Some of the im-portant parameters include the vapor pressure and theboiling point of the fuel, the fuel and air temperatures,the chamcteristics of the fuel spray, and the type ofignition source.

The effect of varying the boiling point, the arornat ichydrocarbon content, md the ol&n content of fuelsthat fall witiin the AN-F–58 specification has beenstudied at simuhtted+dtitude conditions in a number ofturbo-jet combustors of different design. The perform-ance parameters that were investigated include com-bustion efficiency, altitude operational limits, and cw-bon formation.

Early investigations indicated that fuels containingaromatic hydrocarbons deposited more carbon in com-bustors than parailinic fuels. Studies on annular- mdtubular-type combusim~ have indicated that carbon de-posits may be correlated with hydrogen-carbon ratio

COh&ITNiiE FOR AERONAUTICS

and volumetric average boiling point of the fuel. ‘Wrelative quantities of curbon to be expected from fuelsof different characteristics may be estimated by usc ofthis correlation.

Fuel Synthesis

In smriecases fuels required for evaluwtion in turbojetand rarn:jet comlmstors are not uwilable from wmmwr-cial sources and in these cases the NACA prepurcs thofuels by isolation from petroleutn stocks or from nm-terials that will yield the desired product ill a fvw steps.A lmrgefractionating column htis prcrwcl to be of coLl-sidernble assistance in preparing clrum qunntitiw ofthese ftiels.

Emphasis has been giwm to the synthesis of high-clcnsity hydrocarbons because the aircm ft and missilesfor high-speed use me volume limited. By s~mlyingthe effect of Systemically changing the ndccularstructure on the heating vnhle and “physical propw!.icsof hydrocarbons, there is a his for predicting the typcof molecular structure thnt will give opt immn heatrelease per unit volume ancl optimum physicrtlproperties.

SUBCOMMITTEE ON COMBUSTION

Effect of Operating and Design Variables onbustion

com-

Long-mnge f undamentul resmrch on the physics andthe chemistry of the coml.mstion process has IJccncon-tinued. ‘1’he resenrch comprises attempts to analyzeflames for the rnoleculur spwics existing therein andstudies of the effects of different cnhdy(ic agents onflame speeds. Both lines of ut(ack are .nimcdnt ad(lingto the knowledge of the chemical nmchrinismof burl~ing,

Following a completed study of the effwts of air-velocity, tenl~)erature, and pressure on the energy,power, and duration of a spark cliscluwgefor diffwcntelectrode diameters and spticings, research was ini-tiated on the energies required to ignite flowing com-bustible propane-air mixtures. These ignition studieshave been comple~d for n pressure range of 1 to 2pounds per square inch.

In the continuing efiort to estal.dishgeneralized rulesand principles about the operation and the design ofgas-turbine combustors, several combustom of differentbasic design were investigated over a wide mngo ofaltitude. The designs included both annular and tubu-lar types, and deo included combustors representativeof both.United States and foreign design.

With previously acquired knowledge of the inthl-ence of operating variables, or inlet conditions, on tlmperformance of gas-turbine cornbust.ors,systematic re-search was conducted on specific design variables for

REPORT h’ATTONAL ADVISORY

~--turbine combustors. In one such study, the effectof fuel-nozzle size and fuel-injection pressure on theahitude performance of an annular combustor was de-termined. Inlet-air conditions were independentlyalterecl in the study. Results indicated that reducedfuel-nozzle size or increased injection pressure in-creased combustion efficiency at lo-ivheat-input valuesbut produced levier temperature-rise limits. Variationsin fuel volatility were made to verify the possible ~-planation for the observed phenomenon.

In another investigation, systematic research wasconducted on the arrangements of the air passages inthe wds of the combustor liner, or flame tube.

One method of auegnenting the thrust of u turbojetengine is to lead some of the air from the compressorto H separate combustion chamber vd~ere it is burnedwith fuel. The air thus t&en from the main combus-tors is replnced by a fluid, for example, -water. A study-wascompleted to establish the optimum location forinjecting the -i-raterinto a combustor and to determinethe maximum quantities of water that can be injectedwithout seriously depreciating the combustor perform-ance.

Rtim-jet combustion requires stable, ei%cientburningin a high-velocity air stream with a minimum of physi-cal obstruction in the air stream. Because basicresearch showed the high efficiency of incandescentsurfaces in supporting and stabilizing combustion, aperformance comparison was made between a con~en-tiontd single-row ram-jet burner and burners embodyingone, two, three, and four rows of gutters immersed inthe combustion zone.

Thermod.ynarnic charts and computational methodspreviously established hare been used to centinue theewduation of rocket-propellant systems that will givemaximum thrust per vieight flow and per ~olume flow.Experiment nl research on propert ies and characteristicsof propellants has been conducted to estabIishthe debgeeof suitability for any desired application. Propellantsoffering the possibility of greatly increased range ofrocket-propelled aircraft m compared -withalcohol andliquid-oxygen propellants have been experimentallyewduated in 100-pound-thrust engines.

Kinetics of Rocket-Motor Reaction

Design of the smaLlest, lightest, and most efficientrocket engine for a given thrust presupposes basicknowledge of the relation between propellant-injectioncharacteristics and combustion. High-speed motionp~ctures of the combustion of liquid oxygen and gaso-line in a rocket engine showed the effect of se-ren meth-ods of propellant injection on the uniformity of com-bustion. The flame front was generally found to extendto the injector f aces and fill the injection systems showed

COAIMI’ITEE FOR AERONAUTICS 29

considerable nonuniformity of combustion. Pressurevibration records indicated combustion vibrations thatcorrespond to resonant-chamber frequencies.

Heat-transfer research at high Reynolds numbers and ‘high temperatures imth with and without liquid filmson the inside malls of a duct was initiated to providebasic information pertinent to rocket cocding.

SUBCOMMITTEE ON COMPRESSORS

Gas-turbine power plants for high-speed and long-range aircraft require light compact compressors withlarge air-flow capacities and high efficiencies. In addi-tion, the compressors should be mechanically sturdy andeasily manufactured in order to obtain reliable engineshaving a comparatively low initia~ cost. These goalsare the objective of the research on two types of sub-sonic compresso=the axial-flow and the centrifugalor mixed-flow type-and on the supersonic compressor,each of which appermsto ha-reparticular advantageousappIications.

‘l%eoretictd Compressor Aerodynamics

Theoretical studies have been concentrated on deter-mining the compredie potential flow associated withthe conf&wation of the compressor and its operating _ _conditions. Basic general equations governing thethree-dimensional compressible flow in turbomachineshave been developed in convenient forms to be used forboth theoretictd and experimental investigations. Thes+eiptions vrereemployed in determining the radial flowinvolved in, and its effect on, the design of two axial-flow compressors and a turbine with a large number ofblades. The solutions obtained are for sn~alljlarge, andinfinite blade-row aspect ratios. As reported in Tech-nical Note 1795, the radial motion is found to consist ofa component due to the taper in the passage -walland anoscillatory component caused by the difl?erent radial ‘–”variation of specific mass flow at different stations alongthe axis of the machine. The effect of the radial flowis increased with higher aspect ratio and flow 31achnumber.

With the amunption of the Linearized pressure-vol-ume relation, a solution of the problem of designing anairfoil with any tlworeticaIIy attainabl~ prescribed, di-mensionless velocity distribution in a potential flow ofcompressible fluid was obtained by a method of corre-spondence between potential flows of compressible andincompressible fluids (Technical h’ote 1913). me ._ __,method was then extended to include the designing of ——cascade blacles for a given turning of the air flow and uprescribed velocity distribution along the blade.

Besides the potential-flow studies, immstigations have ““been made to determine the magnitude of some of tie ._.:


limitations imposed on compressor performance by vis-cosity and compressibility. From consideration ofavailable information on boundary-layer behavior, arelation of profile thickness, maximum surface velocity,Reynolds number, velocity diagram, and solidity hasbeen established for a cascade of airfoils immersed in atwo-dimensional incompressible fluid flow. The effectof various cascade-design parameters on minimum re-quired cascade solidity has been developed by severalillustrative examples (Technical Note 1941).

A theory developed for the analysis o&two-dimen-sional compressible flow in centrifugal and mixed-flowimpellers is presented in Technical Note 1744. The va-

riables taken into account are: Tip speed, flow rate,number of blades, and passage-area variation. Theimalysis is first developed for arbitrary blade shapesand then appliecl to several specific shapes of blade.

An analytical study was made of four combinationsof subsonic and supersonic flow in the rotor- and stator-blade passages of axial-flow compressors. A compres-sor with a rotor-contained normal shock ancl subsonicvelocity at the stator entrance was theoretically capnbleof producing a total-pressure ratio of about 3.5 perstage. A compressor with a rotor-contained normalshock and supersonic velocities at the stator entrancepermitted total-presure ratios above &Oper stage Acompressor utilizing supersonic flow throughout the ro-tor with complete diffusion in supersonic stators permit-ted total-pressure ratios above 5.0 per stage. A con~-pressor with subsonic velocity in the rotor and super-sonic velocity in the stator entrance permitted pressureratios of 2.2 per stage.

Experimental Compressor Aerodynamics

Investigations to determine methods of improvingthe performance of single-stage and multistage axial-tlow compressors and of investigating the pertinentf undamentak of flow are continuing. In genera], theresearch effort has been concentrated on increasing thepressure ratio per stage in order to reduce both theweight and the cost of axial-flow compressors.

An investigation was conducted on a 14-inch-diame-ter model of a typical inlet stage of a multistage axial-flow compressor to study the effect ofithe velocity dia-gram on pressure ratio,efficiency, and weight flow. Theresults of this investigation indicated that a compressorinlet stage designed on the basis of a symmetrical ve-locity diagram at all radii is capable of high flow capac-ities at reasonable stage preesure ratioa and permits theuse of the high rotor speeds that are desirable from thestandpoint of high pressure ratio in the latter stages ofa multistage comprewor.

Several investigations have been conducted to deter-mine the performance of large centrifugal compressors

COMMITTE& FOR AERONAtilCS

thati are components of- aircraft gas-turbine powerplants. A series of four comprtmor configtwations-wasexperimentidly investigated to determine posildesources of losses and to tinalyze improvements affwxlwlby subsequent modifications. Design chaugee in theimpeller and the diffuser resulted in a 3&percen~ in-crease in weight flow (without any orer-all ch~nge inpower-plant size), a 5-point increase in ovw’-all ctli-ciency, and an increase in p~itk pressure ratio of 11 per-cent at the operatiug speed of the power plant.

The eEects on compressor performance rcsultiugfrom injecting water (or other fluids) into the impellerfor augmentation purposes have been analyzed. .Forthe inlet conditions considered tind for pressure ratiosbelow 8:1 this study showed that water-air ratios lessthan 0.05 were very effective in increasing pressuroratio and weight,flow. When the water rate is incrcaswlabove this figure, however, the excess vratm is essen-tially wasted, as far as compressor performance is con-cerned. The method of analysis was then applied to thodata obtained from three Itirge clouble-eutry centrifu-gal comprewors operated with wuter inject-ion a~ thoimpeller inlet at a water-air ratio of 0.05. Althoughthe pressure ratio and weight flow of the compressorwere increased, the power rcqtiired to drive the com-pressor increased to such an extent that the acliitbaticefficiency wtis reduced by over 10 percentage I)oints.This impairment in efficiency does not nullify the gtiinsin engine performance resulting from the ohservcd in-creases in pressure ratio and weight flow.

An analysis of a compressor utilizing supersonic flowt,hrougllout the rotor and experimental invest igntionson two-dimensional turning passnges Lo simulaLo tlmblade shapes of such a compressor have I.weu complehd.The measured 10SWSon the two-dimensional turningpassrtges varied from 5 to 15 percent of the inlet tittig-nation pressure, the smallest 10SSbeing ohined for apassage in which separation on tho convex surfncowas minimized through introduction of u f awmddopressure gradient.

Vibration AnaIyses of Compressors

An investigation was conducted to determine the fac-tom affecting the vibration of axial-flow compressorblades. :Inlet disturbances at the cntrunce guide vaneswere found to affect the vibrations of all stages of a10-stage compressor. In general, the tendency was toincreassblade vibration, but in some cases the arrangc-mnt of the disturbances had the beneficial effect ofreducing vibrations. Of the various fnctuw tending todamp blade vibrations, aerodynamic damping wasfound to be the most important. Approximately four-fifths of the total damping in the experimental con~-pressor was attributable to aerodynamic effects.


The effects of centrifugal fume on the flutter ofcompressor and turbine blades -were investigated. ‘llvomethods of analyais were used in the investigation. Thefirst was an approximate method, employing the con-ventional assumption ti~at the flutter motion could berepresented by just two degrees of freedom, the fun-damental uncoupled torsion, and bending modes. Inthe second method, a solution of exact equations offiutter motion in a field of centrifugal force was ob-tainecl. Both methods showed essentially the same re-sults: Centrif ugal force can be detrimental by reducingthe critical flutter speed, but if the flutter coefficient iskept below approximately 4, vihich is generally the casefor compressor and turbine blades, there is little pos-sibility of the occurrence of flutter at 10-wangles ofattack. Hence, the important cases of observed com-pressor and turbine-blade flutter are of the %.tilIing-flutter”’ type.

Under NACA sponsorship the Mmsachusette Insti-tute of Technology has designed and irmstigated acondenser-type microphone to take instantaneous pres-sure measurements under conditions typical of thoseexisting behind the rotding blade elements of a com-pressor or turbine. The principal design element ofthis instrument is a dome-shaped diaphragm which isfitted to a stanclard pressure indicator and recordingsystem. The dome-shaped diaphragm was show-n tohave a better frequency-sensitivity characteristic thanu flat-plate-type diaphragm, Also, with regard to theproblem of instantaneous pressure measurements, theresponse of a pitot-tube system to large-amplitudepressure fluctuations has been studied. A sound gen-erator was designed to produce the large-amplitudefluctuating pressure and various pitot-tube systems-wereinvestigated.

SUBCOMUI’IT’EE ON TURBIN%S

Experimental and theoretical research investigationson turbines having the geneml objectiws of improvingthe efficiency, flow capacity, and expansion ratios acrosstie turbine are continuing. B1ade shapes that sntisfythe aerod~amic, thermodynamic, and st-h require-ments, and which are easy to manufacture> are essentialto the de-relopment of the turbines for gas-turbine powerphmts of high-speed, long-range aircraft. R=arch onmethods of cooling turbine blades is also receiving em-phasis becauseturbine cooI@ offers a meansof utilizinglow-alloy materiaIs, as -wellas permitting operation athigher turbine-inlet temperatures.

Theoretical TurMne Aerodynamics

The similarity of the aerodynamic problems arisingin compressor and turbine research makes the results of


nearly aII the theoretical research on compressors ap-plicable to turbines. ~Lw, owing to the fact that thesolidity of turbine blades is usualIy much greater thrmthat of compressor blades, the comparatively simple“stream-filamentn methods can he used to correlate the-oretically the turbine-blade shapes with the velocitydistributions in compressible flow. By using the busicprinciples of the stream-filament method, a step-by-stepprocedure has been devised for desi=tig turbine ~lades-with given -ielocity distributions on the suction surfaces(Technical Note 1931).

The difficulties in instrumenting rotating turbineblades to obtain fundamental infonuation about thecomplex-flow phenomena have resulted in resmrch withboth two-dimensional and annular static cascades. .Acomparison was made between the calculated designperformance of u gas-turbine stator blade and its per-formance in a sector of an annulm cascade tunnel.Information was obtained on the three-dimensionaleffects that occur and the influence these eilects haveupon various performance parameters. The gas veloci-ties on the blade surfaces were computed by the stream-flament method and then compared with the experi-mental values (Technical Note 1810).

The amdytical determination of the performance ofa gas-turbine engine under -rarious operating conditionsor the prediction of enggne performance at other thandesign conditions requires a knowledge of the completeperformance of ench of the engine components. ~method was developed for estimating turbine per-formance from the blade an@s and flow areas.” Themethod is based on amunpt ions that determine the~ariation of turbine-blade pressure losses and turningangles with variations of angle of incidence and en-trance ~lach number. The performance of a turbine ofan aircraft gas-turbine engine -was determined by meansof the analytical method and the results comparedfavorably with esperimentsd datti.

~ method of obtaining turbine-performance charac-teristics by use of a combination of t vie-dimensionaland three-dimensional stationary-cascade investia@ ionshas been developed. The object of this study was toreduce the experimental -work required to predict tur-bine performance.

Experimental Turbine Aerodynamics

A family of turbine rotor-blade designs based on one-dimensiomd flow theory and incorporating systematicchanges in design variables is being investigated. ~single-stage turbine having 40-percent reaction had amaximum internal efficiency of S4 percent at a total-pressure ratio of 3.5 and a hub-tip ratio of 0.8.

The air flow in turbines generalIy encounters favor-able pressure ~graclients and therefore the problenl of


attaining high blade-element efficiencies with turbineblades is not nearly so acute M in the case of compressorblades. The losses arising from blade-tip leakage andfrom improper flow distribution ahead of the turbinerotor, however, may seriously impair turbine pel+nml-tmce. In order to detertiine somtiffect.s of stator-tunecmgle and blade-tip leakage, a single-stage turbine wasinvestigated with etrdor~coneangles of 70° and 0° ~ndwith two stationary shrouds: (1) A labyrinth, no-leak-age shroud and (2) a cylindrical, stationary shroud.In combination with the labyrinth shroud the 0° ccme-cmgle stator gave a turbine efficiency slightly higherthan the 70° cone-angle stator. When tie labyrinthshroud was replaced by the cylindrical shroud, the effecton efficiency was negligible.

Theoretical Turbine Thermodynamics

Analyses have been made to explore the efficiency ofvarious methods of blade cooling. Analytical investi-gation of the use of ceramic coatings as insulation onwater-coded turbine blades indicatecl that, in order toobtain practical results, a very low-conductivity coat-ing must be used. With such coatings, many metalsand alloys with intermediatee concluctiviliee (betwwm15 and 210 Btu/(hr) (sq ft) (°F./ft) ) might be suit-tible for turbine use.

Preliminnry studies of the use of low-alloy nmte-.rials for cooled turbine blades for ctpplicat.ion to &turbojet eugine were n-rode. It was found that the cur-rent.values of turbine-inlet temperatures could be ob-tained with air-cooled blades made from low-alloy mn-terials by having fins inside the blades to give large heat-transfer surfaces. Slight increases in specific fuel con-sumption are necessary, however, for maintaining thethrust of the engine when use is macleof coded turbinebltides.

Experimental Turbine Thermodynamiea

Experimenhd data on the heat transfer from hot gwsto n cooled cascade of impulse blades and from cool gxsto the mrne cmcade of blades in a heated state have beenobtained. To date, the use of a velocity and a pres-sure that are the nvernges of the velocities and the pres-sures about the blade as the basis for Reynolcls numberdetermination has provided the best correlation of thesedata. lt vms found that the heat-transfer coefficientsfor impulse blades me higher than those for reactionblades and that the blade angle of atttick IMs a “largeeffect on the heat-transfer coefficients.

An investigation was conducted to determine theeffect of turbine-disk cooling with air on the efficiencynnd tile power output of a rndial-flo-w turbine. Overthe normal operating range of. the turbine, vimying thecorrected cooling-air weight flow from approximately0.30 to 0.75 pound per second produced no measurable


tiect on the shaft horsepower or adiahatic otkicnc,y.Va+ng the turbine-inlet total temperature from 1,200°to 2,000.””R. caused no measurable chtingo in the cor-rected cooling-air weight flow.

Stress and 17ilMation Analyses of Turbines

In the preliminary stuge of engine design or in rIcomparative evacuation of various types of power plant*it is ksi-rable to have a method of obttiining the ap-proximate weights of the various engine componentsand of determining the relative influence of vnrions de-sign variables, An analysis -wasmade tu show the ef -fects..of blading aspect ratio and solidity, the rn.t,ioofcentrifugal stress at the Made roots to that in the disk,and the ratio of wheel diameter nt the blwlc rod towheel cliameter at the blacle tip on turbine-wheel weightfor a wheel model based on the DeLavtil equation fur adisk of uniform strength (Technical Note 1S14).

Coneiderable attention was directed t,o stress and vi-bration problems of hollow blades for gas turbines.Hollow blades are subject to more serious vibrationsthan those encountered in solid blades. h au invcsti-gcdion of two blRdes of similar mrodynamic clesign, onesolid and one hollow, it was fuund that approxinmtelytwice as many vibration modes vicrc readily cxcitccl inthe hollow blade as in the solid Made. l%wuliar [o theholIow blade was a -rery easily excited “breathing mode”in -which the two sides of the blade mowxl altvrnntclytoward and then away from ench other, causing slrcssconcentrations to be produced at the lcwling and trnil-ing edges of the blade.

A direct rntional method has l.)cen derclopd for de-signing turbine disks to operate at any desired stressdistribu~ion resulting from the centrifugal effu% uf ro-tation and thermal effects of conduction f ron~ t.hc hot.gas. Blthis method, it is possible to clesign dislw eachportion of which operates at a uniform le.vcl of sWcs9-to-strength ratio, thus resulting in cmginc9 of minimum-weight tind most efficient U(ilization of scn~ce alloyingmaterials (Techuical Note 1957).

An experimental investigation was comluctcd 10check a theory ~sphtining the occurrence of rim crmk-ing of gas-turbine wheels with weldccl blades. Thetheory asserts thut cracking is the result of subjectingthe rim material to pltistic flow alternate y in eonlprcs-sion as. a result of high-temperature grndien~ tind intension ns n result of resiclunl strcses upon cooling. ltlthe experimental investigation, a disk that htid previ-ously been used in an engine and several small simu-lated turbine disks centaining machined slrws concen-trateions were subjected to thermal cycling similar tothat undergone by disks in service operntion. The oc-currence of rim cracking in accordance with theoreticalpredictions, particularly their occurrence during the

REPORT NATIONAL ADVLSORY COMNHT’IXE FOR AERONAUTICS 33

predicted cooling portion of the cycle, veritied thetheory and pointed to several remedial measures thatcould bet akento minimize or prevent such rim cracking.

SUBCOMMI’M’EE ON HEAT-RESISTINGMATERIALS

FumhunentaI Factors Meeting the Strength ofMateriels

Certain gas-turbine parts must withstand thermalshock caused by rapid coding and heating. k analy-sis was made to determine -whichproperties of ceramicmaterials affect their resistance to fracture by thermalshock. A criterion was developed from this analysisand was qualitatively vefied by experiment. Resist-ance to fracture by therm-d shock was shown to be de-pendent upon thermal conductivity, tensile strength,thermal expansion, and ductility modulus (ratio ofstress to strain at fracture) (’l%chnical Note 1918).

Phenomena such as age hardening, annealing, andorder-disorder transformation depend on the ability ofatoms to migrate through an atomic lattice. Onemethod of determining the movements of atoms withina lattice is to study the rates at which metals diffuse intoeach other under controlled conditions. A special caseof diffusion in metaIs is the case of self-diffusion. In atheoretical study an expression for the diffusion con-stant for sdf-diffusion in metals was derived based onthe assumption that se1f4iffusion occurs by the vacancymechanism (Technical h’ote 1856).

Simple bonding experiments were made to indicatethe compatibility of various metals and of ceramics toform a ceramal (a mixture of high-melting-point metaland refractory oxides or carbides). The temperature,time at temperature, and atmosphere suitable for sin-teting the ceramal -wereindicated by the results of thesepreliminary experiments. The bonding experimentsconducted with boron carbide and each of four metaIsshowed that cobalt, iron, and nickel formed a bond.@zone between the metal and the ceramic and that chro-mium showed physical -wetting characteristics on theceramic (Technical Note 1948).

The NACA sponsored an investigation at the Uni-~ersity of Michigan on the fnndamental effects of aagingand solution-treating on the creep properties of low-carbon NT–155alloy. In this investigation the reactionstaking place during aging were partially defined andmeasured. A theory was outlined describing the roleof precipitation and its effect on creep properties.

Another phase of the University of Michigan inves-tigation concerned the effects of heat treahnent and hot-cold work on properties of low-carbon N-155 alloy. Itis expected that the trends shown in this in-restigation

for the various treatmentswill hold for other alloys. Itis not expected, however, that the optimum treatmentswill be the same for all alloys. It was concluded thntwide ranges in properties of most of the better alloysdeveloped for gas-turbine service have been due to theMuence of heat treatment and procezsing conditions.The treatments used have been of more influence thanwide ranges in chemical composition. The propertiesof alloys in the hot--worked condition are quite variablebecause hot-workirg simultaneously involves scdutiontreatments, aging, and hoLcold work.

As a means of extending basic lmowledge on heat-resisting materials the NACA has sponsored an inves-tigation at the U~ve~ity of Notre Dame ‘on the chro-mium-cobaR-nickel alloy system. A preliminary surveyof this system has been completed at l@OO C.

Evahxation of 31aterial PropertiesShort-time tensile strength, thermal-shock resistance, __

coefficient of linear expansion, and dem~ityof seven hot-pressed ceramics were determined. The compositions ofthe ceramics viere maaguesiumoxide, titanium carbide,zirconium carbide, boron carbide> 85 percent siliconcarbide plus 15 percent boron carbide, silicon, andzirconia stabilized with 6 percent lime. Titanium car-bide hail the best resistanceto thermal shock and showedthe best o~er-aII characteristic of the sewn composi-tions in~est.igated.

The properties of ceramale of titanium carbide plus5, 10, 20, and 30 percent of cobalt, molybdenum, andtungsten -werein-restigated. The properties evahmtedwere elevated-temperature tensile strength, elevated-temperature modulus of rupture, coefficient of linearexpansion, and density. A study was aIso made of themicrostructure of the ceramak. The ceramaIs exhibit-ing the highest strength as determined by modulus-of-rupture evaluations at 1,600° and 2,000° F. were 80 per-cent titanium cm-bideplus 20 percent cobalt and at 2,400°F. were 90 percent titanium carbide plus 10 percentmolybdenum. It -wasthus shown that the use of metalshaving better refractory properties imparted higherstrengths at the higher temperatures (Technical Note1915). Further studies of these titanium-carbide-baseceramals were made to determine their oxidation-perm~tration characteristics at various temperatures and ex-posure periods. The ceramaIs containing molybdenumshowed the least resistance to oside penetration and thetungsten and cobalt ccramals were about equal in thetime-temperature range for which the data were com-parable. The oxides formed on the molybdenum ceram-aIs had no protective value in inhibiting further otida-tion, ~hereaz the oxides formed on the tunatien andcobalt ceramals serred as protective coatings (TechnicalNote 1914).

9Mii&51-4


An investigation sponsored by the NACA at theUniversity of-bfichigan produced datfi on stress rup-ture and creep properties of S-590 alloy, S-816 alloy andInconel-X alloy from large forged disks similtir tothose used for gas-turbine wheels.

The investigation at the Th.ivemity of Michigan alsoshowed that the 100- and 1,000-hour rupture strengthat 1,200° and 1,300° F. varied approximately linedywith the cobalt content of alloys with 20 percent chro-mium, 20 percent nickel, 4 percent molylxlennrn, 4 per-cent tungsten, 4 percent columbium, and the remainderiron. CobaR apparently stabilizes and controls thetype and distribution of precipitated particks -whichgive these alloys their high-temperature strength.

An investigation was akmundertaken at the Univer-sity of Michigan to determine by means of tensile testewhether service in comkmstionchambem of jet engines,estimated to be at 1,700”0to 1,800° F., would increasethe brittleness at 1#00° to 1,400° F. The resultsshowed that the operation at the higher temperatureswould not adverselj a“ffectthe. ductility at 1#00° to1,400° F. as measured in the tensile test. In fact, cluc-tility seemed to be improved by exposure at the highwtemperatures.

Performance of MateriaIs under Operating Con-ditions

An investigation of turbojet combustion-chamberliners from two types of engines was conducted to de-termine the factors contributing to liner failure bycracking. It ivas found that buckling was produced ator near most cracks by thermal stresses that resultedfrom over-all temperature gradients and from Ioealtemperature gradients at. louvers in the liners. Cracksthat formed in the buckle were attributable to thermalfat igue. The results imlirated that cracking maybe re-tarded ancl liner life prolonged by removing stress-raisers. producecl by punching operations (TechnicalJSote 1988).

—.—-- -..

~er~mals offer promise of permitting higher operat-ing temperatures in gas-turbine engines. The problemsarising in the use of a carbide-type ceramal forgas-turbine blades were evaluate-d. Specimens of Rcermnal composed (by -weight) of 80 percent titaniumcarbide plus 20 percent cobalt were investigated. Gas-turbine blades of this material were operated in a quasi-eervice evaluation unit. The results indicated that thiscarbide-type ceramal may be suitable for gas-turbine-blnde operation at relatively high temperatures forshort times (Technical Note 1836].

The effectivenessof chrome plating in preventing oxi-clntionand erosion of graphite rocket nozzles was inves-tigated. This investigation was conducted on a 1,000-pound-thrust acid-aniline rocket. The results showed


that a thin chromium plating on the internal surface ofgraphite nozzles was effective in preventing the oxida-tion and the erosion that occurred during a run withunprotected graphite.

As a part of the research program on protective coat-ings for high-temperature mat erials an investigtitionwas co&cted on two ceramic coatings developed by theNational Bureau of-Standarcls to determine their suit-ability for turbine-blade application, C)pcration ofblades -with tlese coatings in a turbojet engine indlcatcdthat the fusion temperature of one .vras too low andsome of the coating was thrown off. The other coatingremained intact through 33 hours of operation exceptfor a small fimouut of flaking caused by mechanicaldamage to the blades.

SUBCOMMITTEE ON PROPULSION.SYSTEW3ANALYSIS

Comparative Performance of Various Engine Cycles

A method for predicting equilibrium performance ofturbojet engines was developed, with the i-wsumptionof simple mode] processes for the componcn L*. Resultsof the analysis vrerepresented in terms of dimensionlessparameters derived from cr~tical engine dimensionsand over-all operating variables. The analysis wasmade for an engine in which the ratio of wxial-inlet-nir”velocity to compressor-tip velocity is conshmt tind ap-proximates that of turbojet engines with axial-flowcompressors (Technical Note 195G).

The characteristics o&a turbine and a propeller wereinvestigated to determine the conditions of maximum-eficiency operation when utilized as an imlependentturbine-propeller combination. A method wus devel-oped for matching turbine anclpropeller churacteristicsfor maximum ove.r-all. efficiency. l’he condi~icms formaximum-efficiency operation were found to be definedadequddy by turbine-inlet tempemture, pressure ratio,and propeller speed for all flight conditions inwst.igatcd(Technical Nate 1951).

Theoretical and experimental investigations weroconducted to determine the perf omnance potentinlitiesof a highly compounded engine of the gas-generatortype consisting of a two-stroke-cycle compression-igni-tion eng&e driving a compressor with n turbine drivenby the exhaust from the engine. The turbino f urnishedthe useful work of the cycle. Analyses of this ty~]eofpower plant have indicated a very low specific fuelconsumption combined with low spectic weight andfrontal rtrea. The gas-generator-type engine has beenevaluated analytically by comparing the pay-load-rangoperformance of an airplane equipped -withthis type ofpower plant with the same airplane equipped with sev-eral other centempormy engines. Experimental inmst.i-

REPORT NATIONAL AIWLSORY

gations have been underttikento check the resumptionspertaining to the performance of the reciprocating-engine component of the gas-generator-engine mdysis.

The rery high manifold pressures associated with thegas-generator-type of engine require the use of a high-pressure-ratio compressor system. An analysis of thovarious compressor combinations indicates that com-pressor systems can be provided that should gi-re satis-factory operation and control for aRitudes from sea.level to 50,0CHIfeet.

Thrust Augmentation

The performance of different types of “clamshell”’variable-area exhaust nozzks for turbojet. engines hasken determined on afterburners and standard tailpipes, using fall-scale turbojet engines at zero-ram sen-level conditions. This type of nozzle properly de-signed is mechanically reliable under after-burningconditions. Efficiencies of the various types were viith-in Oto S percent of the efficiency of conventional fised-area exhaust nozzleS

The operational and performance characteristics oftwo different t-ypesof commercial afterburner and sev-eral NACA afterburner designs augmenting the thrustof con~mercial-type turbojet engines have been deter-mined in altitude test fticilities. Determinations weremade of the operable range of afterburner fuel ffow~burner-ignition characteristics, stability of combustion,and burner-shell temperatures~o~er a range of simu-lated-flight conditions for each conflbwration. Markedimprovements in the operation and the performance oftail-pipe burners were obtained by means of systematicmoclificationa of the flame holder and fnel system.Results obtained with these mod.if3cationsextended theknowledge of design requirements for tail-pipe burners:

Thermodynamics and Heat TransferBased on an amdysie of the compressible-flow rnria-

tions occurring in heat-exchanger pa~ages, workingcharts have been constructed to enable comnmient deter-mination of the preesure chop suetained by air flowingin turbulent motion through a smooth-wail passageheated to constant-wall-temperature conditions. Theeffect on the flow process of a high temperature differen-tial between the passage wall and the fluid may beaccounted for in the use of the charts by a method de-rived from recent NACA experimental data.

The experimental inw.stigation to obtain surface-to-fiuid heat transfer and associated pressure-drop infor-mation at high surface temperatures and flux densitieshas been extended to average surface temperatures of2,050° R. and heat flux densities of 15,000 Btu per hourper square foot. h additional in-instigation was con-ducted with air flowing through an electrically heated


silicon-carbide tube at average surface temperatures upto 2,500° R.

ControI ProbIems

The problem of accurate fuel metering for recipro-cating aircraft engines has become of increasing im-portance in recent yeara because of the de-relopment ofIorg-rangej high-altitude aircraft. An anal~ Of air-

craft-carburetor design w-ascompleted which dealt pri-mariIy with altitude-compensating systems. A prac-tical method was derived, -which presents a possiblemeans of obtaining accurate altitude compensation(Technical Note 1874).

The current development of gas-turbine engines indi-cates a future trmd toward a wide variety of enginetypes. & new- engines are developed by combiningbasic components of existing engines, the control prob-lem presented by each engine type vi-illbe different. Ageneral algebraic method of attack on the problem ofcontrolling gas-turbine engines having any number ofindependent variables was developed employing opera-tional functions to describe the assumed linear char-acteristics for the engine, the control, and other units ofthe system (Technical Note 1908).

A basic problem confronting the designer of enginecontrols is that of determining the dynamic behoviorof the complete engine and control system under vary-ing conditions of operation. A method of analysis wasdeveloped to obtain the frequency response character-istics of a complete system assuming the system to belinear and provided appropriate transient data wereavailable (Technical A’ote 1935).

SUBCOMWI’ITEE ON LUBRICATION AND WEAR

NeedIe Bearings

An analytical and experimental in}-estimation wasmade of needle bearings at rotating speeds to 17,000rpm. The analytical factors considered included:Stresses due to aircraft maneuvering loads, deforma-tions due to operation at high temperature, and inter-nal forces -within the bearing. An expr~on for e~thrust was derived wherein end thrust -wasfound to beapprozimately equa~to the external load multiplied byan o~er-all equivalent coefficient of friction. Thisequivalent coefficient of friction was experimentally ob-tained over a wide range of operating conditions. It-was found that the stiffness of the needle -wasa eig-ni6cant factor with shaft deflection present. The ex-perimental results for end thrust developed within aneedIe bearing agreed qualitatively with the derivedexpre*on. In general, the percentage of slip -withinthe bearings increaeed with increase in speed. The data

36 REPORT NATIONAL ADVISORY COMMI’JTiEE”FOR AERONAUTICS

indicatwl that the orbital needle speed may becomeindependent of shaft speed at high values ofishaftspeed tind at low loads (Technical Note 1920).

Bearing ErosionThe erosion of bearings is a constant source of trouble

in numy bearing applications. An investigation wasconducted to determine the effect of high shear rates onerosion of common benring metals. Studies were madewith filtered oil flowi~o at mean surface shear stressesof 11 and 43 pounds per square inch (roughly corre-sponding to mean surface rates of shear of 1.0X 10°and 19X ICYreciprocal seconds?respectively) for periodsof 6 hours. Under these conditions, specimens of cop-per, silver, and lead showed no indication of erosion orother surface damage. Studies made by flowing un-fdtered oil through a flow path, “one surface of whichconstituted the erosion specimen, produced a pseu-doerosion that resembled erosion found in aircraftpower plants. This pseudoerosion was found, byvisual observation, to be caused by small foreign par-ticles creating a multiplicity of small scoreson the speci-men surface. It was further observed that particlessmaller than the oil-film thickness were capable of pro-ducing another type of erosion if the oil in which theparticles were carried was forced to change directionsuddenly (Technical Note 1887).

S1iding and Rolling Friction

An experimental investigation was conducted toestablish the oxidation characteristics of molybdenumdisulfide (MoS,) and to determine the tiect of such

oxidation on its role ns a solid-film lubricrmt for rela-tively high temperature conditions. The oxidationcharacteristics were established with e]evated-ttmipcrn-ture X-ray-diffraction techniques. The effects ofvarious degrees of oxidation of surfaces coated withMoS, orIfriction at h’~h sliding velocities were studkd.With sIiding veracities between 50 and 8,000 feet, porminute and a load of 269 grams, a cozting of JIoS2serving as a solid-film lubricant maintained low frictiotlvalues during its oxidation as long m an effective sub-film of MoSa remained. Films of the oxidation productof MoS% (namely, molybdenum trioxide) alone pro-duced very high friction. When heated in air at 750°F., MoS, began to oxidize at a very low rate, the rateincreasing steadily and becoming high at,110500F. rIMIabov~ When heuted to 1,000° F. in vacuum, MoSSmaintained its original hexagonal structure (TechnicalNote 18E2).

Oil FoamingUnder certain types of operation in nircraft the foam-

ing of lubricating oil can prevent tidequatehdwicat,ionof critical engine components. An investigat ion of thefundamental factors affecting the foaming characteris-tics of lubricating oils was conducted at Stanford Uni-versity under the sponsorship of the NACA. ‘1’Imresults of this in-restigation are reported in TeclmicalNotes 1$40,1841,1842,1843, 18+1845, 1846, and 1847,Data vreie obtained on a number of commercially avail-able products showing their tendency to foam relativeto each other. In addition, theories were proposed forthe behavior of the various materi81sstudied.

AIRFRAME CONSTRUCTION RESEARCH

COMMI’IT’EE ON AIRCRAFI’ CONSTRUCTION

The Committee on Aircraft Construction has duringthe past year reviewed the programs of research underits cognizance with particular emphasis on the problemof- predicting the fatigue life of aircraft. The impor-tance of take-off, landing, and taxying problems asinfluenced by the increasing speed and size of aircrafthas also received attention. As in the past, a consid-erable amount of the hTACAresearch effort on structuralmaterials and structures was performed under contractby universitiesand other nonprofit scientific institutions.

Fatigue Life of AircraftResearch pertaining tdairframe construction involves

both the determination of the operating conditions ofthe airframe w well as the investigation of- suitablematerials and structures to meet these conditions. In-vestigation of the factors affecting structural designintreduces problems of joint concern to the structures

engineer and the aircraft-loads engineer. One of theseproblems is the prediction of the life of uircmfl Maffected by fatigue,

During the ptist few years the trend in aircmft designand operating procedures has been such as to cause thaproblem of fntigue of aircraft structures to become ofserious -concern. In line with this trend the Committeeon Aircmft Construction during the past year lMSreviewed both the fatigue problem and the programthat has been under -way to-alleviate it.

The problem of predicting quantitatively the fatiguelife of aircraft structures under service operating cm-ditions maybe considered to consist of two phases: (a)The detaminat.ion of the repented service loads and(b) the determinant ion of the resistance of the structureto the repeated loads. These two phases of the problemare interrelated: The resistance of the structure to re-peated lcmds depends on the manner in which the loadsme applied; yet adequate measurement and expression


of these loads require a knowledge of how the resistanteof the etructure depends on the manner of loading.This interrelation requires that the fatigue problem beregarded as having a third phase (c), the developmentof a reliable theory relating fatigue life to manner ofloading.

Phase (a) of this problem consists of the detmmina-tion of repeated service loads as functions of the im-portant. operating and structural parameters, ancl theadequate expression of these loads. During the pastyear, emphasis has been pl~ced on gust loads, as theseappear to be of the greatest importwme. The resultsof gust-loads studies are outlined in the section entitled‘Subcommittee on Aircraft Loads.”

Phase (b) of this problem consists of the determina-tion of fatigue properties of basic materials, the effectson these properties of stress-raisersresulting from f ab-dication?the fatigue properties of structures, id finallythe effects on these properties of the manner in -whichloaclsare applied. The first two parts of this phase arediscussed in the section entitkl “Subcomntittee on Air-craft Structural 31aterials.n The latter two parts areconsidered to be in the sphere of interest of the Sub-committee on Aircraft Structures and investigationsdirected toward the sdutiou of these problems are cur-rently under way.

Phase (c) of this problem, which concerns the e-ralua-tion of the fatigue damage caused by the cun~ulativeeffect of vm-ious loack, appears possible only after alarge amount of fatigue data has been obtained underVerycarefully controlled conditions. Having such data,it should be possible to appmise existing damage theo-ries and, if necessary, to de~elop a new theory. It isintended that the investigateions now under way shouldprovide satisfactory data for establ.idment of a relia-ble damage theory.

SUBCOMMITTEE ON AIRCIMI?I’ STRUCTURES

stress Distribution

The buckling resistance of a plate to one type of loadis usually lo-mred by the presence of another kindof load. The most important of the load combinationsis that consisting of shear>which ariss in the wingskin from twisting, and compression, -which arisesfrom bending. The buckliqg strength of flat platesunder the simultaneous action of these two loads wasstudied experimentally through tests on lo~u squaretubes (Technical Note 1750). The readts were foundto validate the use of the theoretical pmabofic inter-action curve which applies to an isolated plate.

In conjunction with the foregoing investigation, atheoreticd study was made of the buckhg behavior of

CWiIM~EE FOR AERONAUTICS 37

a seard~ square tube under torsion and compressionin order to evaluate the extent to which the bucklingstrength of a square tube diffem from that of four iso-lated plates (Technical Note 1751). The major differ-ence found was thzt for a square tube more than 35percent of the critical shear stresscan be appLiedbeforethe compressive strenag$his in any way reduced, whereasfor an isoIated plate the presence of some shear alwaysreduces the amount of comp~ive stress required forbuckling.

In most studies of the compressi~e buckling of flatplates, the prebuckling stresswas assumedto be uniformthroughout the plate. There are many practical caw, --however, in which the compressive stress is not uniformbut varies from one loaded edge to the other, as, for ex-ample, -whenthe plate forms pmt of the upper skin ofan airplane wing in bending. The buckling of a simplysupported plate uncler a linearly varying compressive

——

stress w-as therefore studied theoretically (TechnicalNote 1S91). The results showed that a plate with alinear stressgradient will buckle with .anaremge stressthat is lovrer, but -with a maximum stress that may be -appreciably higher, than the uniform compreesi~e buck-ling stressof the same plate.

Stability

M a conference on aircraft structures held at theLangley Laboratory in May 1948, it -wasmentioned thatthe use of -rertical posts to replace interior sheur -webswas being considered seriously by the aircraft industry.As a first step in the study of this type of construction,the compressive buckIing of simply supported tht platessupported in the interior by equaIly spaced rows of rigidposts wus investigated. It -wasfound that such platesbuckle vrith either tmnsverse nodes or longitudinalnodes pnssing through the rigid posts, the occurrenceof one buckling mode or the other depending upon thenumber and spacing of the posts.

For the achievement of high strength to resist thecompreske forces arising from wing bending, the up-per surface of the wing is usually reinforced by longi-tudinal stiffene~. Charts giving the compressi~e buck-liqg strength of simply supported flat plates w rein-forced have therefore been computed (Technical N“ote1825). Plates with one, two, three, or an infinite num-ber of identical, equally spaced stiffeners havi~~ zerotorsional stiffness -wereconsidered.

The comprwsion & of the wing is sometimes sta-bilized by chord-wise mther than spm-nrise stiffeners.The re.dts of a compressive-buckling analysis have beenused to construct charts for the minimum-weight designof this type of construction (Technical Note 1710).

The design of wing spars having shear webs withuprights and the design of chordwise-stiffened, vring-


skin pmelstoreaist wing torsion require aknowleclgeof the buckling strength of transversely stiffened longplatea under shear. This problem wos studied theoreti-cally for simply supported flat plates in which the stitl-eners are identical, are equally spaced, and have zero tor-sional stiffness (Technical Note 1851). Experiment:Llresults were found to be in good agreement with theo-retical results.

The longitudinally stM’ened panel of small aspectratio has long been one of the most important struc-tured components for which large amounts of experi-mental data have been accumulated. In order to makethese data useful in design, a system of direct-rendingcharts had been developed to maim possible the deter-mination of the stressand panel propertiw required fora given loading; the first set was published last year,Two additional sets have been published as TechnicalNotes 1777 and 1778 for panels of 24S–T alloy withY-stiffeners and Z-stiffene~, respectively.

The Y-stiffener (with straight webs) had been devel-oped in order to achieve higher efEciency than thatwhich could be obtained by conventional stiffenershapes. As a further improvement Y-stiffeners withcurved webs were developed. Tests in a series of pan-els with such stiffeners of ‘75S-T aluminum alloyshowed increased efficiency in panels designed to failat high stresses (Technical Note 1787).

Previous work on panels with formed stiffeners haclindicated that the Z-stiffener, which is very desirablefrom the production point of vie-w,has also a high struc-tural efficiency, In order to give thorough covernge OJ1this type of stiffener, a program oq..pgnels with extruded(instead of formed) Z-stiffeners was undertaken. Thedata obtained to-date on 75S-T alluminum-alloy panelshave been published in Technical Note 1829.

The investigation of. the effect of rivet diameter andpitch on the strength of- compression panels has beencontinued. In Technical Note 1737, a marked effect ofrivet strength on the local buckling strength of Z-stiff-enerswas reported.

The dingonal-tension theory was intended originallyfor benms with thin webs, in which the ratio of shearstress at f tiilure to buckling shear strew (the so-called“loading ratio”) was of the order of sevmd hundred.Because of the various trends in design, much lowerloading ratios are now frequently encountered, and itwas deemed advisable to check the accuracy of thetheory for low loading ratios. A series of tests waetherefore made on thick-web beams, and, after somemodifications, the theory -wasfound to be applicableto beams having loading ratios 1sssthan 2.5 (TechnicalNote 1820). Additional test data were also provided onthe failure of websby tearing along the rivet line (Tech-nical Note 1756).


As a contimation of the study of the bucldil]gstrength of curved elements of the airplane skin, tlmcase of curved rectangular plates ul](ler compressionwith simply support ecl edges and a centrally locatedlongitudinal stiffener of zero hmionnl stiffness wasstudied theoretically (Teclmicnl Note 187!)). llccauscpanels of moderate or huge curvature have been foundto buckle in axial compression at loads below the theo-retictd value, fin empirical modification of the tluxmti-cnl solution wns suggested fur use in design,

The tension skin of an airplmle wing and the ribsconnecting it to the compression skin have finite stiiE-ness and wil], in genera], distort along with the comp-ression skin when buckling of that skin occurs. Forthin wings it Jnay therefore be necessary to considerthe stability of the wing M R whole in addition to thestability of its individual compwlent~. h a first steptoward the solution of this problem, the buckling ofparallel tension nnd compression nlembws connectedby elastic defloctiorml springs was studied (TechnicalNote 1823). This case is an idealization of the type ofconstruction in which the rib spacing is SUMI1by com-parison Wth the spar spncing.

The existing theory of shear lag, th~t. is, of st res dis-tribution in shells of the type used in aircrnft construc-tion, is based on a number of simplifying assumptionswhich introduce errors of unknown magnitude. Theshear-lag analysis of wing corers, for instimcc, is lxrsedon the assumption that the transferee ribs are infinitelystiff, and it was known that this theory would lend tover.v large errors in the shear stresse9 in some cases. Asimple approximate method was thercfmw tlevclopcd(Technical Note 1728) which gives a reasonably accu-rate estimate of the shenr st resees as shown by a seriesof tests.

Ultimate Strength

In designs calling for a high degree of struc(uralstiffness, the buckling stress mny be above the clasticlimit for the material. An empirical correlation l)c-tween such plastic buckling stress and tho stress-strai~jcurve of the material, -whichenabled the buckling stressto be easily computed, was reported in the Imeviousannual report for the case of conl]nwssion. The samecorrelation was justified tlworetically by the plastic-buckling theory reported in the previous ~nnual.reperk.Additioid experimental confirmation of this correla-tion has now been obtained for IV3-lh magnesium-alloysheet formecl into Z’s (Technical Note 1’714) and forlong simply supported phltes of 14S-TG aluminum nlloy(Technicil Note 1817). In Technical Note 171.1--anempiriciil formula was also developed for the nltinmtccompressive strength of furmed Z-sections and channelsections of l?S-lh magnesium-alloy sheet aml 2-M-T


and l’iS-T aluminum-alloy sheet. Some data on ul-timate strength were aIso reported in Technical Note1817.

The investigation of plastic buckling presented inTechnical Note 1556 was extended to apply to the caseof simply supported Metalite-type sandwich plates incompression (Technical hTote18%2).

A series of torsional tests by Notre Dame Universityon stiffened structural specimens having the cross sec-tion of a D-tube were reported in the previous annualreport. The tests reported corered only specimens ofconstant cross-sectional area. These tests hare nowbeen extended by Notre Dame University to includespecimens of varying cross-sectional shapes.

The University of Alabama has inveatig~ted loadsand deflections in statically indeterminate structureswhere one or more of the members me stressed abovethe proportional limit of the material. Theoreticalanalyses were found to agree very closely with test re-sults of three coplanar, pin-ended structures.

At supersonic speeds, skin Klction can cause largeincreases in the temperature of the airframe. The Oc-currence of this aerodynamic heating has stimulated twophases of structures research: First, the determinationof the basic properties of nmterials at the high tempera-tures expected and, second, the development of methodsof structural nnalysis that include temperature effects.Studies have proceeded on both these phases. In linewith the first phtise,compressive stress-strain dat~ havebeen published for two aluminum alIoys-WS-T3 andRiS=T6-for temperatures up to about 700° F. and forvarious exposure times and rates of loading (TechnicalNote l&37). In line with the second phase, tests weremade on the plate buckliwg strenggh of H-sections atelevated temperatures (Technical h’ote 1806). It wasfound that the compressive strength of plate elementsatelevated temperaturea can be calculated by the samemethods that apply at room tempersture. It is onlynecessary to know the stress-strain curve for the mate-riaI appropriate to the temperature under consideration.

Deformation

Multicell wings have been fa-rored over corrrentionalsernimonocoque vrings in recent high-speed cksigns.Worli on the stress and strength analysis of such con-struction is proceeding. A paper has been published(Technical Note 1749) devoted to the determination ofrelations betvieen the ceklar shear flovis and the ratesof cell twist, and cases have been incIuded in which therate of twist varies from celI to cell. The relationsapply to uniform beams consisting of identical cells.Included in the paper are an nna]ysis of the shear flowassociated with spmm-ise rnte of change of antiekstic


curvature and dso a f orrnula relating the torsionalstiffness to the number of cells.

.

The tmalysis of plate structures loaded beyond theelastic range requires a bow~edge of the p+yaxial plas-tic stress-strain relations of the material. A variety oftheories has been proposed for these plastic stress-strainrelations. Some preliminary experiments of a crucialcharacter have led to the conclusion that none of theexisting theories is entirely satisfactory and an attempthns been made to devise one in better agreement withexperiment. As a result of this effort, a theory for “” -the phwtic stress-strainrelations has been detised whichconstitutes a radical departure from the main currentsof thought on phu+kicity(Technical Note 1871). Theformulation of the theory was guided mainly by theph-ysicnl considerations with respect to the mechanismof plastic deformation which is assumedto be slip. Thetheory is in better agreement -with the aforementioned -experiments than previously existing theories, but moreextensive experimental checks must be made before itsvalidity can be fully assessed.

In dynamic and aeroelastic wing analyses, relation-ships between load and deflection are necessary. Load-defkction relationships that give the deflections at anumber of dissrete stations in terms of the loading in-tensity can con-reniently be expressed by any one ofsevwralmatrix methods. The use of these methods nnda comparison of their accuracy are discussed in Techni- ‘-cal Xote 18M. In addition, it is shown how the nccu-racy of tlese methods may be improved, and the cal-culation time reduced, by the nse of weighti~~ matrices.

%ructurrd EfficiencyThe necessary condition thnt the wing surface of

modern high-speed aircraft remain smooth uncler highIoads has Ied to the consideration of the sandwich platem a substitute for sheet-stringer construction. Sancl-wich pIates consist of two thin sheets of material sepa-rated by a low-density, Iow-stiffness core whicht thoughcontributing Iit.tle to the strength of the plate, serveato increase tremendously the fiexural stiffness of theload-carrying faces. The increase in flexuraI stiffnessis somewhat offset, however, by deflections due to shearwhich become appreciable because of the Iow stiffnessof the core.

One type of sandwich called 31ettiliteemploys a coreof balsa -mod with the grain normal to the metaI faces.The compressive buckling of this type of sandwich hasbeen in-instigated theoretically and checked againstavailable test data for the cam of flat rectangular plnteswith simply supported loaded edges and clamped un-loaded edges (Technical Note 1886) as vreIIas for thecase of all edges simply supported (Technical N’ote

40 REPORTlJATIOl!?ALADVISORY

1822). The case of shear buckhng of long simplysupported plates has also been investigated theoretically(Technical NOte1910).

The Polytechnic Institute of Brooklyn has also in-vestigated the bending and buckling of rectangularsandwich plates. Equations were. developed for cal-culating the deflections and buckling load of rectangularsandwich panels under transverse loads and edgewisecompression. The equations were scdved for the caseof a simply supported plate under compression and theresults have been presented in graphical form.

Vibration Characteristics

The natural vibration modes and frequencies of air-planes often form the basic parameters in an analysisof the response of an airplane to dynamically appliedforces. A theoretical solution for thesevibration modesand frequencies must of necessity be made by someapproximate method because of. the complexity of theairplane structure. One such approximate method ispresented in Technical Note 1747 for the general prob-lem of coupled bending” and torsional vibration of anol]uniform wing mounted at an angle of sweep on ufuselage. This rnet.hod makes use of the energyapproach in conjunction with the natural bending andtwisting modes of tin unswept uniform benm to derivethe characteristic equations describing symmetrical andautiiymrnetrical modes of vibration of the wings andfuselage. Numerical examples are also given and theresults show that a desired mode and frequency may becalculated with good accuracy using lo-w-order deter-minants.

Among the factors ordinarily neglected in the bend-ing-vibrat ion analysis of wings are (a) the additiomdflexibility of the wing due to shear defo~rnation of thespare and (b) the additional inertia loading due to theangular accelerations of the wing elements. In orderto assessthe importance of these two factors, they wereincluded in a theoretical analysis of the nutural f requen-cies of uniform beams, with various boundwy condi-tions, in bending (Technical Note 1909). Both theshear deformation and the rotary inertia were foundto lower the natural frequencies. Charts were providedto permit a quantitative evacuation of the lowering ofthe frequencies.

Research Equipment

During the past yetir a unique combined-load testingmachine has been pImecl in operation at the LangleyAeronautical Laboratory, This machine permits appli-cation of forces and mm-nentsabout three perpendicularaxessimultaneously. The machine is greatly facilitatingthe study of structures under various combinations ofaxial loads, shears, and moments.


SUBCCEWWITEE ON AIRCRAFf’ STRUCI’URALMATERIALS

The majority of the investigations on aircraft 6iruc-tural materials have been cmried out by cou~racts withuniver~ties and other nonprofit,scientific organizat ions,These immstigations have complemented the programon materials for power plants.

Fatigue of MetaIs

A commonly recognized gap in infm-nat ion about thefatigue behavior of aircraft, materials is the lack ofcomprehensive testclata on one ~otof any sing~ematerial.At the same time, there is a serious lack of strictlycomparable fatigue test data for competitive matcrial~.Therefore plans were made to investigate ~athcr fullythe fatigue behavior of each of three metals commonl,yused in airframe construction: 243-T and 75S-T nlu-minum alloys and 4130 steel. It was planned 10obtaindata on a number of items including:

(1) Fatigue studies of unnotchwi sheet over the fullrange from completely reversed stressesto stressesvary-ing about a high mean tensile stress.

(2) Fatigue studies of notched specimens cowring arange of notches and, for each type of specimen, n rangoof stress conditions.

(3) Fatigue damage studiesIn the 1948 annual report, it was pointed out that.

Battelle Memorial Institute had completd invcstig.l-tions of most of item (1). During the past year 13:tl-telle Memorial Institute htiscontinued its irrmstigationsprimarily under item (2) along with scnno cxhmaionsof item (1) that appeared desirable.

For the studies under ite]n (2} it }~its necessary [odesign sismestandardized ftitigue specimens with shwss-concentration factors of known magnitude, Holes,notches, and fillets have been widely used for this pur-pose bemuse they represent, to some extent at least, ljr*c-tical cases of stress concentration. It WM founfl, how-ever, that-there was insufficientinformation avnihhlc onthe stressconcentrations produced by notches m-d filletsto cover the range that was consideral imporhmt. Pho-toelastic investigations were therefure initiatwl in orderto provide the necesmry information,

The Illinois Institute of Technology conductw-1thesephotoe]astic inv@igat,ions and determined f~ctors ofstress concentration for both grooves nnd fillets in barsunder tension, as well as distributions of principalstresses along the section of symmetry through thogroovesl.

The Lmlgley Laboratory has studied theeffect of plas-ticity on stress concentration. In the vicinity of holes,notch% ancl other discontinuitiea of structure, high-


stress peaks are dereloped when a load is applied. Ifthe peak stress is beyond the cIastic limit of the mate-rkd, there will be local plastic yielding; after release ofthe loa& residual stress -d remain in the structure,and the peak stresscaused by successive applications ofthe load -d be decreased. This phenomenon was stud-ied by tests on a series of large panels with round holes(Technical Note 1705). The results are espected to kuseful in de~eloping methods of fatigue analysis.

Sandwich MaterialsThe Forest Products Laboratory has continued inves-

tigations of sandwich materiak. They have completedan investigation of strength and elastic properties ofhoneycomb-type core materials fabricated from resin-imprea~ated myon-mat fabrics. The honeycomb corematerials fabricated from resin-impregnated rayon-matfabric do not appear to be better over-all core materialsfor use in sandwich construction than resin-impregnatedpaper honeycomb cores of equal density. However, forsandwich applicat.ions requiring a high-tensile-strengthCorel the. myon-mat honeycomb core material would bemore efficient than a paper core of equal weight..

The Forest Products Laborsto~ has conducted pr.e-Iiminary tests on adhesi~es for banding sandwich con-structions of aluminum facings on paper honeycombcorw. ~ total of 14 gluing processes was evaluated bytension testa on specimens of l-inch aluminum cubesbonded to a resin-impregnated paper honeycomb core.

The Forest Products Laboratory has also completedan analysis of the shear strenggh of honeycomb coresfor sandwich constructions. The analysis was under-taken to arri~e at a mathematical f ormula by which theshear strengths of honeycomb core materials could becalculated. It was assumed that each cell wall actedindependently, like a plate supported and loaded aIo~rits edges, and that the shear strength of the honeycombwould be determined by the failing stressof thess plates.A similar analysis had been made by the Forest Prod-ucts Laboratory in the past on the compreash.-estrengthof honeycomb cores.

Magnesium-Cerium Wrought Alloys

A program on the development of ma=gnesium-ceriumwrought aIIoys at Battelle 31emorial Institute underhrACA sponsorship showed that the wrought alIoyshave substantially lower creep resistance than the castalloya of similar composition, and that the effect of heattreatment was far greater than the effect of variationsof alloy compositions which were studiecL This pro-gram viaspreviously reported in the 1947annual report.

Inasmuch as previous in-restigationhas indicated thatmagnmium-cerium aIIoys in the wrought conditionpoasesaan unuaual combination of 10-wdensity and rela-

COMMIT’TEE FOR AERONAUTICS 41

tiveIy high mechanical properties for elevated-temper-ature service up to at least 600° F., the AT.ACAhas sup-ported additional investigation of these alloys at Bat-telle Memorial Iistitute during the paat year. Theinvestigation has included both fundamental studiesand aIIoy development because it was felt that thedevelopment of improved compositions -wouldbe facili-tated if there were a better understanding of the factomdetermining the creep resistance of the alloys. .-

SUBCOMMI’M’EE ON AIRCRAFT LOADS

Loads on Wings

The large variations in wing configurations whichhave accompanied the increased speed of modern air-planes and D&&S have made it neccsary to providemore generaI methods for computing span Ioading thanthose that were heretofore available. Before any of thenewIy developed geneml methods can be used with con-fidence, resrdts obtained with them must be comparedwith experimentally determined distributions. Twostudies conducted at the Ames Laboratory have per-mitted such comparisons. In one of these studies thepressure distribution over a highly s-wept w-@ wasdetermined for several angles of attack at supersonicspeed, and in another study the load distribution on asindar wing in combination with a body vm.sdeter-mined for a range of angle of attack thro~oh a range ofsupersonic speed. These resultsshowed that the theoryused predicts the loading due to angle of attack reason-ably -well, particular~y at the higher Mach numbersinvestigated.

In another investigation at the bes Laboratory, theIoad distribution-was determined for a moderately sweptwing at speeds up to a Mach number of 0.91. The re-sults, when compared with the Ioad distribution pre-dicted by theory, were found to be in good agreement.

An exact knowledge of the maximum lift obtainablefrom a -wingand its variation-with speed and -ivithpitch-ing velocity has become more important with the in-creases in wing loading and in operations at high alti-tude. Maximum lift is also a factor not onIy in the loadswhich may be imposed on the airplane but also in theturning radius of missiles and the maneuverability ofairphm= A study of tlie problem was conducted atthe Langley Laboratory using an airplane model whichcordd be pitched at various velocities through an angl~of-attack range frbm zero lift through maximum lift,and measurements were made of the increase in maxi-mum Iift with pitching vehcity. These results werecompared -withsimilar redta obtained in flight on theactual airplane to establish the vaIidity of this method.The resrdts have been reported in Technical Note 1734.

----


A related study has been conducted at the Ames Lab-oratory in which flights were made with a pursuit air-phme to determine the effect of rtite of change of tingleof attack on the maximum lift coefficient over a range ofReynolds number and up to a JUach number of 0.50.This study has indicated that the rate of increase ofmaximum lift coefficient with increasing abruptness ofthe stall is significantly affected by Reynolds number mwell as bfach number. Experiments so far orI this prob -lem have been limited mainly to subsonic and low tran-sonic speeds. Pending the availability of data at hight mnsonic and supersonic speeds, a method lMS beenderived by which the over-ail forces on an airfoil operat-ing in flow -with detached shock waves may be calcu-lated. This method employs a concept of a limitingpressure based on available pressure-distribution dat~~and assumes a shapa of the shock front. ~lile thamethod enablw the maximum lift coefficient to be cal-culated, it can also be used to calculate the lift-dragcurve in all conditions-where the shockwave is.detached.Comparisons show that the method agrees well not onlywith experimental data but also with the results ob-tained with the linear theory for the case where theshock -waveis attached at the leading edge.

The increased speed of aircraft has also necessitatedthinner and more flexible wings so that it has been nec-essary to include the effects of aeroelasticity in designcwlcuhttions. Thus the problem of predicting sptmload-ing has become more compkx than it was a few yearsago. A number of studies has been carried out on thisproblem rind, as a resultt a method has been developedby which the span loading of flexible wings of arbitraryplan form and stiffnessnmy be determined. This work,reported in Technical Note 1876, so systematizes theproblem that calculations may be made in a routinemanner.

Wing flexibility has also affected the related problemof the lateral control available with a given wing con-struction. Wing divergence and aileron reversal, which5 years ago were mainly problems of academic interest,have now assumedmajor proportions. Since spm load-ing and lateral control are linked together, the methoikdeveloped for predicting span loading have been ex-tended to permit calculations of the effects of structuralflexibility on lateral control of wings of arbitrary planform and stiffness. This work has also been system-atized so that calculations are routine.

Theoretical studies of the span load distribution onswept and low-aspect-ratio wings have been extended topermit prediction of tkxfhcts of wing twist. Thiswork has been reported in Tec~nical Note 1772 in whichthe theoretical development is given, together with allfactors required for its rapid application. The methodhas been applied to the study of the effects of wing twist


and the neroclynamic characteristics of some typicalsviept wings.

Studies have been conducted along both experimentaland theoretical lines to provide information relating tomaneuver loads on aircraft. In one investigrdion, re-ported in Technical Note 1729, the wing and tail loadsof a fighter-type airplane were determined from electricstrain-gage measurements These tests extended to uMach number of 0.8. The results in general supportthe conclusions found in previous pressure-distributionstudies.

Loads on TailsResearch on maneuvering tail lends hns been con-

tinued. In the investigation reported in Technical Note1729 the tail loads on a fighter-type airplane weredetermined in flight from electric strain-gage nleasure-ments at speeds up to a 3fach number of 0.8. Theresults of this study verify the f~ct that with an nccu-rate knowledge of the tail-load parwneters, such asmay be obtained from carefu]]y conducted wind-tunneltests,an accurate calculation of the tail loads in nlaneu-vers can be made. The parameters required arc thepitching--moment c~efficienti- the locat ion of the aerody-namic center, and the pitch ing acceleration.

As an approach to the problem of predicting tail loadsat supersonic speeds, a study has been conducted by theLewi& Laboratory in which a theoretical method forobtaining the aerodynamic forces acting on a thin winghas been applied to cletermine the lift and momentsacting on a rectangular tail surface due to linem nndspanwise pwwbolic upwash distributions. This studyhas been reported in Technical Note 1736.

Loads on ControI Surfaces

The investigation in the Langley If)-foot pressuretunnel of the loads on leading-edge flaps on swep~wingshas hen continued. ~.~ure-distribution lklewllre-ments over a half-span leading-edge flap on two wingshaving NACA 64,-112 airfoil sections have been mmle.Both wings were equipped with a half-span split flapand the 43° sweptback wing was invest igatwl in con-junction with a circular fuselage.

As a part of the Committee% continuing program of

research on the determimd ion of the aerodynamic chara-cteristics of various airfoil sections, an investigationof the pressure distribution over t-m NAC~ 66,1-11.5airfoil section with a 20-percent-chord flap has beenmade through a Iinch number range to 0.75 in theLangley 8-foot high-speed tunnel. Two flaps, onehaving the true airfoil contour and one lmving a 30°trailing-edge angle, were investigated. The results ofthis investigation, reportecl in Technimd Note 1596, pro-vide ndditiomd information on the efTectsof wiriation

-—-.-— --. —...- .-. -—. .-—COMkfITTEE FOR AERONAUTICS 43Ji&JKJK1’ NA’1’lUNAb AUVJ.SU.ttX

of the trailingedgs ang18 on the effectiveness of flapsor ailerons at high speeds.

Loads on Bodies and Wiig-Body ArrangementsOne loading problem which has become of major im-

portance is the determination of the division of loadbetween the airplane -wing, tail, and body. TO assistthe designer in more accurately dividing the loads, ananalysis has been made of all the available data on theeffects of wing-fuselage-tail and wing-nacelle interfer-ence on the distribution of the air load among the com-ponents of the airplane.

A theoretical approach has alsabeen made to the load-distribution problem for the case wherein the wing isrelatively srnaII in relation to the size of the body.This con&uration is typical of missiles. Using theassumptions that the body is slender and the wing is oflow aspect ratio, theoretical relations hare been devel-oped for the prediction of the effects of mutual interfer-ence between a body and either a simple or a cruciformwing, The theory and results of some calculations arepresented in Technical Notes 1669and 1S97.

Pressure coticients at local Mach numbers reachingsupersonic speedsha-rebeen determined for the flow overa prolate spheroid and a wing having an NACA 65-010section in the Langley S-foo~ high-speed tunnel. Thevalues of pressure coefficient and Mach number over thespheroid were compared with theory and a study wasmade of the development of a supersonic flow pattern.

Pressure distributions ha~e also been obtained on thewings and fuselage of u scale model of a research-typeairplane through a speed range to high subsonic Machnumbers. These data are of direct use in providing basicstructural loading information.

The effects of a nacelle on the neroclyrmmiccharacter-istics of a swept wing and the effects of sweep on thiswing have been irwestigated in the Langley 16-foot,high-speed tunnel up to Mach nmnbem of 0.61 for thewing-nacelle combination and 0.70 for the wing alone.Extensive pressure measurements, published in Tech-nical h’ote 1709, were made in the course of the in~esti-gation to provide a basis for detailed study of theinterference eflects.

As part of a general study to find the source of w+ngfailures following installation of a wing-tip tank on i-tservice airplane, an investigation was made in the 40-by SO-foot wind-tunnel section at the &aes Laboratoryto determine the effect of wing-tip tanks on the distribu-tion of wing load and on the distribution of wingbencling and twisting. Complete pressure distributionswere obtained over the wing and wing-tip-tank com-bination of the airplane.

Gust LoadaA series of calculations of the transient respon~

induced by gusts in airplane wings has been made andanalyzed. These calculations were made for the purpaseof comparing the ressonse of present-day large trans-port airplanes with that of an older transport airplane,-which has proved itself to be satiefuctory from thestandpoint of gust experience. On the basis of themethod of calculation used and the conditions selectedfor analysis, it is indicated that the newer airplanesshow appreciaMy greater dynamic response in guststhan did the older reference airplane and that increas-ing the forward speed or the operating altitude resultsin an increase of the dynamic response for the gust witha gradient distance of 10 chords. The results were alsoused in studying the advisability of including a tran-sient-stress requirement for gust loads in the civil airregulations of the International Civil AviationOrganization.

One of the problems associated with the design ofairplanes having -i-ringswith large angles of sweep isthe prediction of gust-load factora Previous researchon this problem had been confined to an airplane modelwith a 45° sweptback wing. During the past year, in-vestigations in the Langley gust tunnel of the effect ofwing s-weepon the gust-load factor have been extendedto include a 45° sweptforward wing and a 80° sweptbackW@ The results, presented in Technical Notes 1717and 179-11support the previous Endings that the masi-mum acceleration increment of an airpIane with a sweptwing will be generally less than that for an airplanewith an unswept wing under the same set of flightconditions.

A cooperat i~e flight investigation was undertaken bythe ATACAand the All ‘Weather Flying Division of theU. S. Air Force at CIinton County Air Force Base,Wibningt on, Ohio, for the purpose of determining theeffects of con~pressibiIitYon gust loads. This is be-

lie-red to be the first attempt to obtain aerodynamicinformation by the statistical comparison of airplanereactions. Test data orer n 31ach number range of0.25 to 0.6S were obtained from flights of two similarjet-propelled airplanes in rough nir. The datn andanalysis presented in Technical NTote1937 indicate nocompressibility effects on the over-aII gust reactions ofthe airplane tested within the limits of the dataobtained.

Technical Note 1753presents the resrdtaof an investi-gation made in the LangIey gust. tunnel to determinethe effectiveness of a fixed spoiler in reducing @-load --factors. The redts indicate that the moclel undergoesapproximately the same maximum acceleration in asharp-edge gust with cmwithout the spoilers. In a gusthavimg a finite gradient, ho-wev-, a reduction of 30percent in the maximum acceleration increment wasrealized through the use of the fixed spoilers.

44 REPORT NATIONAL ADWSORY-. .---—--- --- . ----- .—---

SUBCOMMITI’EE ON VIBRATION AND FLUTTER

Flutter of Winga and Control Surfaces

A comprehensive experimental and theoretical studyof the effects of wing svreepbackon the flutter chmac-teristics of cantilever wings throughout the subsonicspeed range has been made. The wings used in theexperiments included a large range of sweepback angleand aspect ratio. Compmison of the theoretical resultswith the experiments indicates that the theory will satis-factorily predict the effects of sweep on the flutter char-acteristics of uniform cantilever wings of moderateaspect ratio.

Investigtitions of the flutterof whgs of various shapesand thickness ratios at tranemic tmd supersonic speeclshave also been made utilizing test~~ techniques of windtunnels, freely falling bodies, and loti-acceleration,rocket-propelled vehicles. The results of these investi-gations have been used to evaluate the applicability ofexisting theoretical methods for calculating flutter clmr-acteristics at supersonic speeds.

An investigation of the flutter characteristics at su-personic speeclsof rnodels of the wing panels of a tran-sonic research airphme has been made by the Langleypilotless aircraft research division using rocket-propellecl models. The.rnodels used in this investiga-tion aerodynamically and structurally simulated thefull-scale wing panels. The structural parameters werevaried over a small range so m to yield design flutterspeeds greater than, equrd to, and less than the designflutter speed of the full-scale wing panel.

The effect of aspect ratio on the undamped torsionaloscillations of a finite mctangulnr wing in a supersonicstream has been reported in Technic&l Note 1895.” Thevelocity potential and aerodynamic-torsional-momentcoeilicients based on the tiearized equations of motionfor small disturbances are derived for a rectangularwing by means of appropriate dtilbutione of movingsources and doublets. The coefficients thus derived arecombined with a mechanical-damping coefficient tostudy the effect of aspect ratio. The results show thatdecreasing the aspect ratio of the wing has a highlystabilizing effect on the undamped torsional oscillations.

A theoretical approach to the prediction of flowsaround and forces on an oscillating airfoil of finite sptmhas been undertaken by the Massachusetts Institute ofTechnology under the sponsorship of the NACA. Theaim of this study is the development of a theory whichincorporates simultaneously the effects of three-dimen-sionality of the flow and compressibility of the fluid.An exact solution of this problem presents great diffi-culties and the work therefore is directed toward anapproximtde theory which is valid provided the aspect

ratio of tke lifting surface is not too small. Earlierwork has included the problem of t~vo-~lil~~el~siol~tilin-compressible flow as a special case. The present workgenernlizw these results so as to take account of com-pressibility in the supersonic range and clescribes amethod of solution for the tl~ree-di~~~c~lsiollnlprolhn.

Aileron flutter or “buzz” at transonic speeds has con-tinued to be a serious problem, and considerable researcheffort has been devoted by the NilCA to ifs solution.One investigation, utilizing both rocket-propelled andwincl-tuimel models, has been mmle to determine dmeffects of mechanical chimping in the control syshm onthe flutter characteristics of dynamically similar scalemodels of the ailerons of a research-type airplane, Thoresults of this investigation show that the occurrence05 aileron “buzz” is critically dependent. ulmn theamount. of damping in the aileron control syshun andalso tend to point up the critical nature of ucruelasticinstabilityy of wing-aileron combintdions at high speeds.

An investigation of the effects of altitucleon the flut-ter characteristics of un ttileron at high sped llNSbeenmade in the Langley 4.5-fout flutter resmrch tunnel.The eflkcts of n]titude were simnlnted by variation ofthe tunnel pressure from 1 to $-$atmosphere which cor-responds to an altituclc variation of from sea level toapproximately 38,000 feet.

An investigation has been made to determine the fea-sibility of studying aileron “buzz” by the wiug-flowmethod, using two swnispt-mmodels differing in airfoilsection. The half -span, quarter-chord, mwd.n~latmxlailerons used on both models were unrestrained exceptfor bearing friction. Aileron ‘%uzz’>was obtained forboth models for ~ small range of Mach number ]\enr0.90.

Flutter of VHngs with Concentrated Weights

The flutter characteristics of a wing are greatlyallecteclby the massand Iocntion of concentrated weightsuch as f uel tanh, enginesiand bombs. An experimentalpro=gram.on the eflkt of heavy conccntrtttcdweights onthe flutter speed and frequency of a straight cantileverwing was prem”onslyreported in Technical Nolc 15!34.These sm-oewing-weight combinations havo been ana-Iyzed by a method involving the (lirecLsolution of thedifferential equations of motion by operational methodsin Technical hlote 184S The theoretical two-dimen-sional oscillating air forces were used in the analysis,The theory accurately predicted the true [Iutter speedeven when that speed was critically dependent. uponmight position and upon changes in flutter mode.This agreement indicates that the theoretital.air forceswere adequate for these experirnenttil conditions andthat tlw structural representation of the problem wasaccurate, Sims this differential-equation method isdifficult to apply to an actual wing lmving taper and


many concentrated weights, a more practicrd methodusing these same experiments and the same themetictdoscillating air forces was e-rolved. This work is reportedin Technical Note 1902. The method involYes the sekc-tion of a few chosen uncoupled modes of stat ic vibrationas generalized coordinates for the flutter analysis. Sincetie differential-equation method of Technical Note 184Sgave good agreement with experiment, inaccuracies ofthe simplitled method are attributable to the approxima-tions in the structural representation. It was foundthat, for the cases with the -weight located forward onthe chord, remdts obtained with the mode analysis weredove the experimental value (that is, on the dangmmsor unconservative side) ; whereas, for cases -witha rear-ward location of the might, the theory predicted toolow a flutter speed. This work indicates that great caremust be used to sekct a sufficientnumber of mocks whenanalyzing cases with large mass coupling and -withforward weight positions.

The mutual tiect of large streamlined bodies, suchas external fuel tanks? on the oscillating air forces ofwings and bodies is not known. In order to gain someinsight into the magnitude and tiect of these air forcescm the flutter characteristics of a wing, the Langley4.5-foot flutter research tunneI was used in an investiga-tion in which the mass and moment of inertia of a con-centrated weight were held constant while the shape ofthe weight was varied. Two general contours of theweight were employed: One a streamlined body andthe other a nonstreamIined body. The results of thisinvestigation show only minor changes in flutter speedand flutter frequency m“th a change in the aerodynamicshape of the body.

The experimental investigation of the effects of con-centrated weight on the flutter characteristics of uu-swept wings previously reported upon has been extendedto the case of sweptback wings. Each -wing carried asingle weight, at a series of spanwise positions on theleading edge and midchord. The investigation co~eredsvreepbackangles of O“,45°, and 60°. The data obtained

AIRCRAFT OPERATING

Theresearch in the field of aircraft operating prob-lems conducted by the X~C~ is concerned with thoseproblems that impair aircraft performance or are re-lated to the inherent safety of the aircraft itself. l%emajor efforts of the ??~C~ in this Se=pent of its re-search activities are on the investigation of turbulence,icing, and fire pre-rention. The research on atmo%pheric turbulence is centered at the Langley ~eronauti-cal Laboratory. The research on icing and & pre-


from this investigation should be of considerable aid tothe airplane designer in choosi~u the optimum bcation,from flutter considerations, of such units as engines andexternal fuel tanks.

Fuselage Vibration Due to Propeller

Severa3instancesof structural failures of the fuselag+3in the vicinity of the propeller plane of rotation onmultienginedairplanes have been reported. It was rea-soned that these failures -werethe resuIt of fatigue ofthe fuselage material resulting from propeIler-excit.edfluctuation in air pressures on the fuselage side. Atheoretical and experimental investigation has beenmade of the characteristics of the pressure field in thevicinity of the tip of a rotating propeller. The resultsof this investigation as repotied in Technical Note 1870show that the shape of the propeLIer blade was not sig-rdicant in exciting fuselage vibration, but that thenumber of blad+ the powerl the tip ~fach number, andthe ratio of tip clearance to propeller diameter weresignificant. It was found that, for a given power,increasing the tip cIearance and increasing the num-ber of blades -wereof greatest importance in reducingfusdage tiration.

Towed Bodi~

Previous analpes of the stability of towed bodiesstabilized by fins have generally assumed that the tow-ing cable remained steady. These theories failed topredict the vio~entmotion of these bodies and the osoil-lations of the cable which have been observed above acertain airspeed. A theoretical investigation was there-fore made of the stabiIity of osdations of the cableand the results are presented in Technical Note 1796.This theory concludes that the vioIent osdations maybe attributed to cable osdlations which originate nearthe airplane and are amplified by aerodynamic forcesas they travel down the cable. hfeans are discussed forincreasing the speed at which these osdations becometiolent.

PROBLEMS RESEARCH

vention is centered at the Lewis Flight PropulsionLaboratory. A limited part of the icing research pro- _gram is under investigation at the &nes AeronauticalLaboratory. Contm.cts for research in thesefields haveaIso been placed with seyeral uni-renities. This work is-guided by the Committee on Operati~~ Problems andits subcommittees, the Subcommittee on MeteorologicalProblems, the Subcommittee on Icing Problems, and theSubcommittee on Aircraft Fire Prevention.


COMMITTEE ON OPERATING PROBLEMS

Effect of Flight Speeda on Aircraft Operation

The analysk.of the data obtained in the V-G programis being continued to obtain information on the imposedflight loads, operating speeds,anclroute roughness. Theresults of the records obtained from V-G recorders dur-ing the prewar period on three different commercial-traneport-airplane types are presented in TechnicalNotes 1733, 1764, and 1783. An analysis of the firstpost-warsample of V-G data obtained from commercial-transport operations indicates that, on the average, thepositive and negative gust-load-factor increments mayeach be exceeded once in about 5.8X 105 flight milesand the never-exceed speed may be exceeded once inabout 5.0X 105flight miles which is in agreement withpast exprience. These resuhs in}icated a trend towardhigher imposed flight loads and apparent increased gustexperience for postwar transport airphmes.

Pilot Escape

The problem of escape from airplanes has becomevery acute with the increases in speed recently achieved.A detailed study with free-flight models has been madeof pilot escape by use .of nose sections that can bejettisoned.

Noise

in the course of the investigation of airplane noise, alarge group of mufflers of-varied design mere evaluatedand repelled i]i Technical h70tes 1688 and 1838. Theresults indicate that the types of available commercialmufflers invest.igttted were relatively ineffective and thatvery little information is rendily available for effectivemuftler design. Theoretical and experimented investi-gations are being continued to determine the basic fun-dwnentds of aircraft-mufier design.

Ditching

Iu cooperation with the Civil Aeronautics Adminis-tration, ditching investigations of all of the four-engiued transport-type aircraft used in scheduled com-mercial operations have been mnde. These investiga-tions were conducted on the monorail in Langley tankNo. 2 using dynamically similar models. In addition,the models of the various aircraft had scale-strengthbottoms and flaps in order that the effect of damage oc-curring during a ditching would be simulated. Theditching behavior of the transports investigated wasgenerally similar and was better than the ditching be-havior of bombers because there is less damage and thedecelerations are lower.

One airplane ditching that occurred during the yearverified the fwct that transport-type airc.raft of the typesinvestigated can safely be ditched.

COMMITI’EE FOR AERONAUTICS

S~COMMI’iTEE ON AIRCRAFI’ FIREPREVENTION

The Subcommittee on Aircraft Fire Prevention lMScompleted the formulation of an experimenttil programthat was started during the past yeur. The initialphases of the research program are current1y under way.

Review of Fire Records and Survey of Fire ResearchAs an aid in esttiblishing the aircraft-fire-prevention

research program, ~n extensi~rebibliography of exkt ]ngliterature has been collected and an analysis has beenmade of the records of aircraft crashes accompanied byfire. Although the primary pnrpose for reviewing theaircraft fire records is to csttddish the fire researchprogram, it has become appmxmt that careful consid-eration has to be given to a metlml whereby datti nrecolkcted from crashes occurring in nornlal aircraftoperation.

Rate and Spread of Aircraft FiresLl order to gain an insight into the rate and spread

of tin aircraftfire following a crash, two experimentalprograms have been initiated. Ill the first progrnm,the propagation of the flame along nn air strenm overa flat surface, in a duct, and over the cxterual surfaceof a streamlined body is being investigated Ior com-bustibles common to current transport tiircntft. Ob-strnctions in the nir strewn and roughnc.~ on the sur-faces are being used to simulate the flow of uir in rindaround tjpical airplane components. Vnrintions in t.hccombustible and form ofi the conlbustible at scn-leveltemperature and pressure are akm being studied.

The second progrmn includes the use of war-surplustransport-type aircraft in simulated take-off or landingincidents thtit usumlly result in fire. The airplanw arcbeing extensively instrumented so that dntu will beobtained on the time history of the esents follrmiug im-pact, including the recording of ignition nml sprmd 01fire,

Inflammability of Aircraft Materials

In addition, work has been continued to eshd.dishpractical concepts of ignition sources and in[iamumbil-ity to determine the state of development of less in-flammable lubricants and hydraulic fluids in order toestablish guides for undertaking research lending to thediscovery of new compounds or additives, and to studythe physics anclchemistry of aircraft tireextinguishing.

SUBCOMMITTEE ON METEOROLOGICALPROBLEMS

Because the operation of airplanes in regions ofsevere atmospheric turbulence reduces the effwt ivc use-ful life of the airplane, emphasis lms been given to the


forecasting and the detection of regions of atmosphericturbulence.

Past work has indicated that the horizontal tempera-ture variations and height of connective actitity give ameasure of the maximum effective gust velocities inclouds in the temperate region. In order to check thisindicated relation for other condition=, an analysis ispresented in Technical Note 1917 of the relations be-t-wee-nthe horizontal temperature variations and themaximum observed effective gust vebcities for the dataobtained during operations of the United StatesWeather Bureau thunderstorm project in Florida andOhio. The results indicate that the relation, when ex-tended to include frontal conditions, appears useful forforecasting the intensity of turbulence for thunder-storms in temperate regions. The relation does notappear useful, however, for forecasting the intensity ofturbrdence in subtropical regions.

In order to evaluate radar as a means of detecting tur-bulence?acceleration measurementsand ah-borne radarobservations were taken during a transcontinental flightof an American Airlines airplane. Although sficientdata were not obtained to give adequate results for ap-plication to airline operations, the analysis indicatedthat some reduction in the turbulence experienced, anda consequent reduction in the risk of encountering theIarger ~nst velocities, maybe obtained by avoiding por-tions of clouds giving a radar echo.

SUBCOMMITTEE ON ICING PROBLEMS

The hazarcl of ice formation on airplanes involwd inall-vieather operations has received continued study.Work on the research program was conducted for themost pnrt at the Levrk Flight Propulsion Laboratory.Previous vrork at the Ames Aeronautical ll~boratoryancl contract research by the University of Californiaat Ims Angeles -wereanalyzed and repmted during thefiscal year.

31eteoroIogical Chamcteriatica of the Icing CIoudThe study of the important characteristics of icing

clouds was continued by means of specially instru-mented airplanes flown through icing conditions. Dataobtained with the same airplanes in succtive yearsshow (Technical Note 1793) unexplainable annual vari-ations in mean values of icing conditions. Analysis ofdata taken over most of the northern United States(Technical Note 1904) ga-reinformation on the regionalvariations of important paramete= Recommendedvulues of meteorological factom to be considered in thedesign of aircraft ice-prevention equipment were es-tablished and presented in Technical Note 1855. Thisreport extends the previous estimat~ of probable maxi-mum and normal icing conditions to corer as completely


as is presently possible all conditions likely to be en-countered.

Investigation of Methods of Ice Protection

JTings and empennages. Two important factorsinfluencing the design of ice-pre~ention equipment arethe amount of water striking the vringg and the area “““-”-on which it impinges. In order to provide informationon these factors, a theoretical investigation was under-taken to study the paths the water droplets dwicribein approaching an airfoil section. Using a diilerentialanalyzer, these paths -werecalculated for a number ofairfoil shapes by the University of California at LosAngeles for the NACA. As a result of an analysis ofthe datn supplied by UCIA, a semiempirical methodwas developed for computing the region covered by thedroplets and the amount of -water striking an airfoil ___section of any arbitrary shape.

Propellers. In order to provide further informa-tion on the ei?ects of ice accretions on propeller per-formance, tlight tests were conducted in natural icingconditions and measurements -were made of the per-formance changes resulting from a number of forma-tions. A study of these data, together -with similardata previously obtained, indicated that, with no iceprotection, performance loss-esnormally would be lowand that large performance losses would be rare.

Jet engines. Ieprotection methods under investi-gntion include inertia separation of freezing water fromthe air before it reachesthe engine, heating the incomingTater-air mixture abcwe freezing by taking hot gasfrom the combustion chambem and injecting it into theair at the duct entrance, and heati~mthe critical sur-faces of the duct and engine to pre-rent freezing of im-pinging water.

Continued studies of the mixing and the depth ofpenetration of high-velocity jets of hot gas injected atright angles to an air stream ha-re provided data forscdecting the size and the arrangement of orifices fora hot-gas bheclback ice-protection system. Adoptingthese practices, small percentages of gas at combustion- ‘“chamber &~charge conditions have successfully pre-vented icing in simulated icing testsof a full-scale axial-flo-wturbojet engine. In further investigations in theLewis ic@ research tunnel, using two-thirds-scale ~~~models of three different types of inlet, the requiredpercentage of bleeclback was determined for a tiderange of icing conditions and the uniformity of mixingwith proper ofice arrangements was demonstrated,The hot-gas bleedback method proved to be a qui&” ‘-””and effective way of providing complete ice protectionon suitably designed installations in which compressorair is not required for cabin pressurization.

48 REPORT NATIONAL ADVISOI&Y

Analysis shows that heating all the critical surfaces onwhich freezing water will impinge will provide ice pro-tection with mgligib~e thrust 10ZSbecause the optimumshape of inlet can be used and the engine air is heatedonly a negligible amount. With this method, the ductentrnnce and walls would be heated by internal hot-gasducts, whereas the engine struts, the inlet guide vnnes,and the accessory fairing would be heated by internalelectrical-resistance elements or by leading hot airthrough hollow paesages in these parts. Preliminaryanalyses and laboratory tests have been completed on amethod of heating compressor guide vanes and first-stage rotor bladea by means of electrical eddy currentsinduced in these parts ..by alternating electromagneticexcitation induced by the rotor, which is modified ta actas a multipIe generator.

Light.airplane induction systems. A Laboratoryin-vestigation demonstrated that safe operation of theinduction systemsof light airplaneacan be accomplishedwith cold ram air by using currently available equipmentprovided subcooled water and snow are excluded by aninertia-separation inlet with a filter and the carburetorthrottle valve is heated to above freezing wh~ever lowpower settings are used at air temperatures below 40°


F. Presmre-injection carburetors, similar to f.hos.eused on transport airplanss, gave reliable meteringunder icing conditions when errntic performance of unatural-aspirating carburetor would haye caused enginopower failure. Simple engine-oil-heated jnckets ttroundthe intake distribution mmlifulds successfully preventedice format ions that reduced engine air flow in unheabxlsystems (Technical hTote1790).

Nonplug~”ng }uel-tanh rents. An investigationmade of the icing characteristics of a recessed under-wing fuel-t ank vent led to a speciaI aiinptation forthis purpose of the NACA flush inIet with dirergentramp side -walls. This type-vent wassubjected to severeicing conditions -when mounted at approximately 70percent of- the chord on a wing unclemurftice at, highangles of attack and showed positive -rent-tube pressureswithout plugging for 60 minutes of icing (TechnicalNote 1789). This development represents a practicalsolution to the problem of safety veuting bla~kler-typofuel cells to prevent collapse due to negative pressuraor the stoppage of fuel flow when ice forms at the vent.The new vent principle should find other aircraft appli-cations, such as oil-tank vents.

RESEARCH PUBLICATIONS

TECHNICAL REPORTS

No.8S3. Wing Plan I?orms for HfgM@ed Fllght. By RobeN T.

Jones.804. Effects of Temperature IMstrtbntion and Elastic Properties

ot’Materials on [email protected]. By ArthnrG. Hohns and Rk’bard D. FaIdetta.

805. Method for Calculating Wing Characteristics by Lifting-Line Theory Using Nonllnear Section Lift Data. ByJames C. SfveIls and RoWrt H.“I?eely.

NM. An Analysts of the Full-Floating Journal Bearing. ByM. C, Shaw and T. J. Nusadorfer, Jr.

S67. A Theoretical Investigation of HydrodynamicImpact Loadson Scallop+xI-BottomSeaplanes and Comparisons wtthExperiment. By Benjamin M1lwltsky.

868. &unm&u’yof Lateral-CXontrolResearch. By LangIey Re-search Department-Compiled by Thomas A. To1l.

S6!).Isolated and Cascade Airfoils with I?rescrlbed VelocityDtstributfon. By Arthur W. Goldstein and Meyer Jeri-Son.

870. Tank Inwattgation of a Powered Dynamtc Modelof a LargeLong-RangeFlylng Boat. By John B. Parldnaon, RolandIl. Olson,and Marvtn I. Haar.

871. Determination of Elaetic Stresses in Gas-Turbine Dtaks.By S. S. Manson.

8i2 Tlworetlcal Study of M Forces on an oscillating or SteadyThin Wing In a Supersonic Main Stream. By I. D. Gar-rlck and S. I. RubLuow.

878. Hfgh-AItitude Fllght Cooling Investigation of Radial Air-Cooled Engine. By Eugene J. Manganlello, Michael F.Talerino, and E. Barton Bell,

No.874. A SimPIMed Method of Elastic-StabMtg Anal@s fur

TIIin Cylindrical SbeIls. By S. B. 13atdorLS76. Application of t.be Analogy Between Water Flow with a

Free Surface and Two-Dimensional Com~reaaMe GasFlow. By W’. James Orllu, Norman J. Limlner, nndJack G. Bitterly.

S70. The Stability of the Lnrninnr Itoundnry I~~yor in a com-preesible Fluid. By Lester Lees.

S77. Summary Re~ort on the High-Speed Charactm’lstlcs of WxModel Wings Having N.40AO&-SeriesScctlona. Ily Wil-liam T. Hamilton and Warren H. Nclaon.

S?& Ana~sfs of Performance of Jet Engine from Cbaracter-istks of Components. I—Aerodynamic and MatchingCluracterLstics of Turbine Component Determirwd withCold Air. By Arthur W’.Goldstein.

S79. Interference Method fur Obttiining the PotwNinl F1OTVPu.st

an Arbitrary Casc8de of Mrfoi[s. By S. Katn Kf,R{J)PrtS. Finn, and James C. Laurence.

S80. Analysis of Jet-l?ropulsion-hgine Colnl)llst!~ll~-Cliu~l~k,rPressure Losses. By L 1rving I’inkel and I htruldShames.

881. Effect-of Coiubnstor-Inlet C!!ndit ions on Pcrfurmanre oran .4nnular Turbojet Comhust ur. By J. HUM-Hrd Ubi!&,Richard J. McCafferty, and Oakley IV. Surine.

SS2. Frequmwy-llesponse Method f{}r Determinant ion of I)y-namic Stal)ility Chnrnct eristics of Airplanes wlt~ Autu-matlc Controls. By Harry Greenberg.

SS3. FII~ht Measurements of the Lateral Control Cbaraclcr-istics of Narrmr-Chot’dAilerons m the Trailing F~lgeOfa FulI-Span S1ottedFlap. By Richard H. Sawyer.

WM.Effects OPSweepbaekon Boundary Layer and Separation.BYRobert T. Jones.

REPORT ltATIONAL ABVISOEY

No.SS5. F1lght Lnrestigatlon ona Fighter-Type M@aneofFactom

Which Affect the Loads and Load Distributions on theVertical Tail Surfuces Dnrtng Rudder Kt&s and Fish-tak By John Boshar.

SS6. Spark-Timing Control Based on Correlation of Mashnum-EcwnoLuySprirk Timing, FIameFront Travel and Cylln-der Pre.ssnre Rise. BF Harvey A. CoolL Onllle H. Hefn-Me, and ‘William ELHayrde.

SS7. Critical Stress of Thin-IVaIled C@!nders h Axial Com-pression. By S. B. Batdorf, Murrg Schildcroub andManuel Stein.

SSS. A Theory of Unstaggered Airfoil Cascades in CompressibleFlow. By Robert A. Spurr and H. Jrdlan Allen.

SS9. Polterra’s SoIutfon of the ll”a~e Equation as Applied toThree-Dimensional Supersonic Airfoil Problems. ByMttx. A. Heaslet, Harvard Lamax, and Arthur L. Jones.

S00. Investigations of Effects of Surface Temperature and Sin-gle Roughness E1ements on Boundary-Layer Transition.By Hans IV. Lfepmsxm and Gertrude H. Film

S91. A Thermodynax.ulc Study of the Turbojet Engine. By Ben-jamin Pinkel and Irving M Karp.

S9!?!?Damping [n P1t& and Rolf of Tr@ngulnr Wfngs at Super-sonic Speeds. By CIinton E. Brown and Mac C. Adams

SW. YeIoc[t~DLstributlons on Two-DimenslonaI Wfng-Duct In-lets by Conformal ?Japping. By W. Perl and H. El Moses.

S64. On sfmI1ar@ Rules for Transonic Flows. By CarlKaplan.

S03. Anal$ws of }“arlatlon of Pfston Temperature wttb P@tonDimensions and Undergrown Cooling. By J. C. Sandersand Vi’.B. Schramm.

S96. PressurMensitive System for Gns-Temperature ControLBy Rhchard S. Cesaro and h-ormtm Matz.

S97. Knocking Combustion Obserred In a Spark-Ignition Enginewith Slmultaneam D~t and Schlieren High-Speed Motion Pictures and Pressure Records. By Gordon EOsterstrorn.

S!}S.A UnffIed Theory of Plastic Budding of CoIumns andPlates. By lil.lbridge Z. StowelL

N)% A General SmalI-Deflection Theory for Flat SandwichPlates. By Charles Libove and S. B. Batdorf.

000. The Use of Sonrce+hk and Doublet Distributions Ex-tended to the Solution of Boundary-Valne Problems inSupersonic Flow. By MLK. & Heaslet and HarvardLomru.

001. Anal@s of Effect of Basic Des@ Variables on SubsonicAsial-Flow-Compressor Performance. By John T.Siinette, Jr.

002. Subsonic Flow o~er Thin ObIique AMoils. By RobertT. Jones.

903. TheorethM and Experimental Data for a Number of NACA&l-Series Mrfotl Sections. By Laurence K. Loftin, Jr.

MM. HstimaUon of F~ and l?+ Knock-Limited PerformanceRatLngs for Ternary and Quaternarx Blends ContainingTrtptrme or other Htgh-Antiknock Aviation-Fuel Blend-ing Agents. By Henry C. Barnett.

303. FnU-Sctde Investigation of the Aerodynamic Character-fatics of a Typical Single-Rotor Helicopter in ForwardFlight. BI Richard C DMeldein and Ram-aond Ii’.Schaefer.

000. Determfnatlon of Stresses in &us-Tnrblne Disks Subjectedto l?IastIcFlow and Creep. By M. B. Mllenson and S. S.MansoL

907. Equations for the Design of Two-Dimensional SupersonicNozzles. By I. Irving PinkeL

COMMI’ITEE FOR AERONAUTICS 49

Ko.90S. Strhiity Deri~atiws of Triangular Wings at Supersonk

Speeds. By Herbert S. Rilmer and Frank S. Malrestuto,Jr.

909. Laminar-BonndarY-Layer Oscillations and Transition onFlat Plate. BYG. B. Schubrmer and H. K. SkramstacL

910. Summary of Drag Charactefi=tics of Practical-CcmWrnc-don Vilng Sectfons. By John H. Quinn, Jr.

91L Ltftlng-Surface-Theorr Aspect-Ratio Corrections to theLfft and Hinge-310mentPammetera for Full-SPan Ek--mtors on Horizontal Tail Surfaces. By Robert S.Swanson and Stewart X. CrandrLL

912. The Interdependence of Vartous TYpesof Autoignition andKmck. By H. Lowell OIaen and Cearcy D. 31tller.

913. Experiments on Stability of Buneen-Burner Flames forTurbulent Flow. BY Mwell XL Bollfnger and DatidT. Williams.

914. Eff~ of CentrL@al Force on the Elastic Curve of aVibrating Cantilever Beam By Scott H. Simpklnaon,Laural J. Eatherton, and Morton B. MiIlenson.

915i.Extension of Useful Operating Range of =ial-l?low Com-pressors by Use of Adj@ble Stator BIades. By JohnT. Sirmette, Jrq and Wiiliam J. Voss.

916. Correlation of the Drag Characteristics of a Typical Pur-suit AlrpIane Obtained from High-Speed Wtnd-Tunneland Flight Tests. By James 3L 3Xssen, Burnett L.Qadeberg, and William T. Hamilton.

917. The Effects of Aerodynamic Heating and Heat Transferon the Surface Temperature of a Body of Revolutionfn Steady Supersonic F1ight. By Richnrd Schemer.

91S. Theoretical Motions of Hydrofoil Systems. By FrederickH. Imlay.

919. Accuracy of Airspeed Measurements and Fltght Cullbra-tton Procedures. By IWIber B. Hueton.

920. The Development and Application of High~ritical-SpeedNose Inlets. By Donald D. BrIals, Norman F. Smith,tmd John B. Wright.

92L Theoretical Symmetric Span Laading at Sub.wnlc Speedsfor Wings Having Arbitrary Plan Form. By Juhn ?Je-Young and Chimles W. Ehtrper.

TECHNICAL NOTES ‘

1143. (Supplement) Charts for Determinhg the Characteristicsof Sharp-Nose Airfoils in Two-Dimensional Flow atSupersonic Speeds. By H Reese Irey, George IV. Stickle,and Alberta Schuettler.

1430. A Theoretical Study of the Dynamic PropMies of Hell-copter-Blade Systems. By H. Reissner and M. ?Jor-cluchow.

WAS. Theory of the Inlet and Exhaust Pro=es of Internal-Carnbustlon Engines. By Tsung-chi Tsu.

1433. An Investigation of Atrcrnft Heatera. XXIX-Compari-Wn of Sereral Methods of Calculaffng Heat Losses fTOmAirfofls. By L. XL K. Boelter, L. hf. Grossmanj R C.MartinelI1, and E. H. Morrin.

145& An Investigation of Aircraft Heaters. SXX-Xo&urnalIrradiation as a Function of Altitude and Its Use inDetermination of Heat Requirements of Aircraft. ByL. M K. Boelter, H. Poppendiek, G. Young, and J. R.Anderson.

14s7. Overbalancing in Eesidutd-Liquidation Computations.By Mred S. Xtles.

1The mkslng numbers in the series of technical notea were releasedbefore or after the DWodcoveredby thfs report.

—

50 REPORT NATIONALADVISORY‘-----—––- ‘-–.-- . . . .— ---

LXXklM1’1”1’ME FL)K AMUJNAUT1LX5

No.1403. AStatLetical Study of Wave Conditionsat Four Open-Sea

LocaIitiea inthe North Pacific Ocean. By L. A. Harney,J. F.T. Saur, Jr., aud A. R. Robinson,

1564. A MetallurgIcel Investigation of a Contour-Forged Dwof EME Alloy. By IP. Il. Eteynolds, J. W. Freemanj andA. E. White.

1.636. A Metallurgical Inves%gation of Two TurbosuperchargerDEWSof 19-9DL Alioy. By E: ID.Reyriolds, J. W. Free-”man, and A. El. White.

W31. Simmgth and Creep Characteristics of Ceramic Bodkw atElevated Temperatures. By hf. D. Burdick, R. H).More-land and R. F. Geller.

lS96. An Investigation of the Section Characteristics of P1ainUnsealed Ailerons on an NACA 66,1–115 Airfoil SectionIn the Langley S-Foot High-Speed TunneL By Arvo &Luoma.

1626. Observations on the Maximum Average Stress of FlatPlates Buckled in Edge Compression. By El. H.tihuet te

1649. Investigation of .a l/7-ScaIe Ptiwered hfodeI of a Tivin-Boom Airplane and a Comparison of Its Stability, Con-trol and Performance with those of a Similar A1l-WingAirplane. By Gerald ‘W.Brewer and Ralph W. May, Jr.

1688. D~mamometer-Stmit Investigation of the Mutlier Used inthe Demonstration of Ltght-Airplane Notse Reduction.By K. R. CZarnecki and Don D. DavLs, Jr.

1696. Chordwlse Pressure Distributions on a 12-Foot-Span WingNACA 66-Series Airfoil Sections up to a Mach Numberof 0.60. By Nancy E. ‘Wall.

1697. The Effects of Compressibility on the Lift, Pressure, andLoad Charncterlstics of a Tapered Wing of NACA 66-Serka A[rfoll Sections. By Morton Cooper and Peter F.Korycinski.

169S Efftwt of Wind Velocity on Performance of Helicopter Ro-tors as Investigated vilth the Langley Helicopter Appa-ratus. BY Paul J. Carpenter.

1760. The Rolling Moment- Due to Sldeafip of Triangular, Trape-zoidal and Related P1an Forms tn Supersonic Flow. ByArthur L. Jones, Tolm R. Spreitei’, and Alberta Alksne.

1703. Dowrnvaeh and Wake Behind Untapered Wings of VariousAspect Ratios and Angles of SIW?.D. BY H. Page Hog:gard and John R. Hagerman.

1704. Investigation of Boundary-Layer Reynolds Number forTransitIon on an NACA 65(=)-114 Airfoil b the LSng-Iey Two-Dlmenaional Low-Turbulence Pressure Tunnel,By Albert L, Brnslow and Fioravante Visconti.

1706. Stnbility Derivatives of Thin Rectangular Wings at Super-sonic Speeds. Wing Diagonals Ahead of Tip Mach LJnes.BY Sidney AL Harmon.

1709. Investigation of the Effects of a Nacelle on the Aerody-namic Characteristics of a Swept ‘iVIngand the IUffectsof Sweep on a VWng Alone. BY Gerald Hteser andCharles F. Whitcomb.

1711. Approximate Relations for Hinge-Moment Parameters OfControl Surfaces on Swept Wings at Law Mach Num-bers. BY Thomas A. Toll and Leslie E. SchneIter.

1714. Plate CompreazIve Strength of FS-lh Magnesium-A.UoySheet and a Maximum-Strength Formula for Magn%slum-Alloy and Aluminum-Alloy Formed Sections, ByGeorge L. Gallaher.

1715. MollferDiagramsfor AIr SaturatedwfthWaterVaporatLowTemperatures.BYReeceV.HensleY.

1716.Tablesof HYpergeometricFunctionsfor UseIn Compres-sible-l?lowTheory. By VeraHuckeL

No.1717. Gust-Tunnel Investtgrttion of a 45” SweIifurward-Wins

Model. By Harold B. Pierce.1719. Flight Measurements of Buffeting Tail Loads. By Ailen R.

Stokke and William S. Aiken, Jr.1720. Friction at High Sliding VeMltIes of Surfaces Lubricated

with Sulfur as an Addl tive. By Robert L. Johnson, ALtxA. Swikert, and Edmond H. Btsson.

1721. Calculation of the Effect of Thrnst-Axis Inclination onPropeller Disk Loading and Comparison with F1igl~tMeasurements. By A. W. Vogclcy.

1722. Prediction of the Effects of PropNlt?r Operation on theStatic Longitudinal Stabillt y of Sfngk-Engine Trnctw’lKonoplanes with Fhtps Retrncted. By Jos@l Weil and‘i’iWlam C. Sleeman, Jr.

1723. A Theoretical Investigation of the EffwA of Yawing Mo-ment Due to Rolling on Lateral OzcilWory Strdil[ty.By Joseph L. Johnson and Leonard Sternfleld.

1724. A Study of Skin Temperatures of Conlcnl Ilodlcs in Supm-sontc Flight. By WiIber B. Huston, Wlvln N. War5eId,and Anna Z. Stone.

1725 Determination of Transient Skin Temperature of ConicalBodies During Short-Time, High-Speed FI1ght. By HSUh.

1726. Spray Characteristics of Four Flying-Boat TIulla M Af-fected by Length-Benin Rntlo. By Willinrn W, HodgmJand David IL TVoodward.

1727. A $implh%d Method for the Determination nml Analysisof the Neutral-Lateral-Oscillatory-Stability Boundary.By Leonard Sternfleld and Ordwny IL Gates, Jr.

172$. Shear Lag in Axially Loaded Panels. By Paul Kuhn andJames P. Peterson.

1729. Flight Determination of Wing and Tnfl Loads on IIFighter-Type AirpIane by Means of St rain-(3age Meas-urements. By William S. Aiken, Jr.

1730. EITk@s of Temporal Tangentlal 13em’ing Acc@leration onPerformmce Charactertst.ics of Slider and JournalBearings. By Demo J. Ladanyi.

1731. Hfgh-Ten]perature Attack of Various Compounds on FoorHeat-Resisting Alloys. By D. G. Moore, J. C. I.tichmond,&nd W. N. HarrLeon.

1732. Calculated Effects of Geometric DIh~ral on the LOw.

Speed Rolling Derivatives of Swept Wings. By M. J.Queijo and Byron M. Jaquet.

1733. An Analysis of the Airspeeds and Normnl Accelerationsof Sikorsky S-42A Airplnnes in C’ommercinl ‘1’rnnsportOperation. By Waiter G. Walker.

1734. InWMigation of the Variation of Maximum Lift for aPitching Airplane Model and Canpariaon with IWghtResults. By Paul W. Harper and Roy Ill. Flnn[gan.

1735. Performance of Exhaust-Gas Blowdown Turbine andVarious Engine Systems Using a 12-Cyllnder Llquld-Cooled Engine. By Leland G. Desmon and Eldon W.Sams.

1736. Theoretical Method for SoIutIon of Aerodynamic Forceson Thin Wings in Nonuniform Supersonic Stream withan Application to Tail Surfaces. By Hurold Mrcls.

1737, Effect of Variation in Diameter and Pitch of Rivets ONCompressive Strength of Panels with Z-Section Stiffen-ers, Panels that Fail by Local Buckling and Have Vari-ous Values of ‘iVidth-to-Thickness Ratio for the Webs ofthe Stiffeners. By Norris F. Dow and ‘ivillimu A.Hickman.

REPORT NA’ITOA’ALADVISORY C031MITTEE FOR AERONAUTICS 51

No.173S. Wind-Tnnnel Investigation at Low Speed of the Lateral

Control CharacterLsttcs of Ailerons havhg Three Spansand Three Trailing-Edge Angles on a Semispan WingModel. By Leslie E. Schneiter and Rodger L Naeseth.

1739. CamparLscm with Experiment of Several Methcds of Pre-dk-ting the Lift of Wings in Subsonic Compresslble FIow.By Harry E. Murray.

1740. An Approximate Determination of the Lift of SlenderCyIindricaI Bodies and Wing-Bcdy Combinations atVery High Supersonic Speeds. By H. Reese Ivey andRobert R. Morrissette.

17-IL Exploratory Wind-Tunnel Investigation of the Effectlv&ness of Area Suction in Elhninating Leading-Edge Sep-aration over an NACA 64@12 AirfoLL By Robert J.h“uber and James IL Needham, Jr.

1742. Stability and ContioI Characteristics at Low Speed of anAirplane 310deIHating a 9S.7” Wveptback Wtng withAspect Ratio 4.51, Taper Ratio O.S~ and CorwentionalTail Snrfaces. By Ternmd E. Lockwoodand James M.Watson.

1743. FIigM Measurements of the Stabfllty, Contro~ and StalMngCharacteristics of an A@ane Having a 35” SweptbackWing without Slots anti with SO-Percent-SpanSlots enda Comparison tith WTnd-TunneI D~ta. By S. A.Sjoberg and J. P. Reader.

1744. Two-Dimensional Compressible F1OWin Conical 31txed-Flow Compressors. By John D. Strmita.

1741. Theoretical Evaluation of the Ducted-Fan Turbojet En-gine. By Richard B. Parisen, John C. Armstrong, andSidney C Huntley.

17-M.Flow of a CompressibleFluld Past a Symmetrical Airfoilin a Wind Tunnel and in Free Air. By Howard W.Emmons.

1747. Determination of CoupledandUncoupled3fodesandFre-quenciesof XaturalVtbrationof Sweptand lJnswept‘J%@ from UntformCantileverJ1odes. By Roger A.hderson andJohn 0. Houbolt.

17-E+.~tdculationof Tunnel-Inducedupwash ~elocltles forSweptand Yawed‘ilYngs. By S. Katzoffand NargeryE. Hannah.

lT40.ShetirFlow in IIulticellSandwichSections. By StanleyU. Bemzoter.

1750.BuckUngTests of Flat RectangularPlatesunder Com-bhvxiSkearand LongitudinalCompression.By Roger~. Peters.

1751.BuckLingof a LongSquareTubeInTorsionand Compress-ion. By BernardBudianskY,3fanuelStein,andArthurC. Gilbert.

l~il Jet-BoundarF-Induced-~pvwshVelocitiesfor Swept Re-lleetion-Planellodela ilounted Yerticalh in 7- by’10-Foot,C1OWQRectangularwind TunneIs. By l?kl-ward C Polhamns.

l=. E~alnatfonof a Fixed Spotleras a GustAlleviator. BYHarryC. 3f@leboro.

1734.An AnaI@s of theMrspeedsandNormalAccelerationofDouglas DC–2 Airplanes in Commercial Transport @er-ation. By Walter G. Walker.

1755. The Design of Low-Turbulence Wind Tunnels. By HughL. Dryden and Ira H. AbbotL

1756. U1timate Stresses Dereloped by 24S-T and Alclad 75S-TAlumhmm-AUoy Sheet in Incomplete Diagonal Tension.By L. R@ss L.eVill.

1757. Performance of Conical Jet Nodes in Terms of Flow anfll’eloclty C.aetlicients. By R E. Grey and H. D. Yilleted.

No.175s.

1759.

1760.

1761.

li62.

li63.

1764.

1765.

li66.

li67.

IiOS.

Properties of 19-ilDL Alloy Bar Stock at MOOeF. By J. W.Freemau FLE. Reynolds, D. N. Frey, and A. Il. White.

Effects of Compressibility on Xormal-Force, Pressure, andLoad Characteristics of a Tapered ‘7i%g of NACA66-Series Airfotl Sections with Split Flaps. By F. E.West, Jr. and J. 3L HallI&s, Jr.

NAC..Aand Ofdce of Naval Research 2Jet rillnrgicd Irivesti-gation of Tvio Large Forged Discs of S-590 Alloy. ByJ. W. Freeman and Howard Cl Cross.

~“mretical Stabtlity Derivatives of Thtn %veptback ‘iWngaTapered to a Point with Sweptback or %veptforwardTrailing Edges for a Limited Range of Supersonic Speeds.By Frank S. ?Jalvestnto, Jr. and Kenneth Margolts,

ControI Considerations for Optimum Power Proportion-ment in Tnrblne-Propetler Engines By Marcus F. Hei&mann and David Novik,

Flight Investigation of a Combined Geared Unbalancing-Tab and Servotab Control System as Used with an AU-Movable Horizontal TatL By Robert Q. 31ungaU.

Influence of TaiI Length upon the Spin-Recovery Character-istics of a Tratier-T~-Atrplane ModeL By ‘Waiter J.Klirmr and Thomas L. Snyder.

Office of Naval Research and NACA MetaIlurgtcaI Investi-gation of a Large Forged Disc of S-S16 Alloy. By How-ard C. Cross and J. W. Freeman.

Wind-Tunnel Inws@3gation of Effects of Tail Length on theLongitudinal and Lateral Stability Characteristics of aSir@-Propeller Atrplane 310deL By Harold S. Johnson.

The Application of Green’s Theorem to the Solution ofBoundary-Value Problems in Linearized Supersonic WtngTheory. By Max. A. Heaslet and Harvard Lomsx

A Rapid (Maphlcnl Method for Computing the PressureDistribution at Supersonic Speeds on a SIender ArbitraryBody of Revolution. By Jim Rogers Thompson.

1768. The F1exible Rectmgular JVIng in Roll at SupersonicFHght Speeds. By Warren A. Tucker and Robert L.A’elson.

1T70. OfEce of Naval Research and NACA Metallurgical Instig-ation of a Large Forged Disc of Inconel X Alloy. ByHoward C. Cross and J. W. Freemam

17TL The Development of Cambered AMoSI Sections HavingFavorable Lift Characteristics at Supercrftical MachNumbers. By DonaId J. Graham.

1~. Theoretical Basic Span Laading C!htiMCterLStb2Sof ~~viith Arbitrary Sweep, Aspect Ratio and Taper Ratio.By Victor I. Stevens.

Iii% The EtYects of Variations tu Reynolds Number between8.0 x 10’ and 23.0x 10’ upon the Aerodynamic Character-istics of a Number of NACA 6-Series Airfoil sections.By Laurence K. bftin, Jr. and WiLUam J. BnrsnaU.

li?4. Calculated Performance of a Com~rewion-Ignition En@n&Compresor-Tnrbtme Combination Based on Ekpertmen-taI Data. By Alexander MendeIson.

1775. Hydrodynamic Impact Loads tn Smooth Water for a Pris-matic Float Having an Angle of Dead Rise of 40”. ByPhilip 3L Edge, Jr.

li76. Hydrc@mamic Impact Lade in Rough Water for a Prts-matlc Float Having an Angie of Dead Rise of 30°. ByRobert W. MHler.

17=. D!rect-Reading Design Charts for 2-IS-T Alumlnnm-AUoyFlat Compression Panels Having Longttud[nal Straight-Web Y-Seetlon StURmer& By Norris F. Dow, Ralph E.Hubka, and William 31. Roberts.


No.1778. Direct-Reading Design Chtut.s for 248-T Aiuminurn-Alloy

Fiat Comimession Panels Haying Longitudinal FormedZ-Section SthTeners. By h’orris F. Dow and Albert S.Keevil, Jr.

1779. Effects of Antisp[n IMlete and Do&d Fins on the Sp[n andRecovery Characteristics of Airplanes as Determinedfrom Free-Spinning-Tunnel Tests. By Lawrence J. Galeand Ira P. Jones, Jr.

17S0. Charh for the Conical Part of the Downwash Field ofSwept Wings at Supersonic Speeds. By Jack N. Kielsenand Edward W. Perkins.

1781. Comparison of Over-All Impact Loads Obtained I)urlngSeaphine Landing Teste with Loads Predicted by Hydro-dynamic Theory. By Margaret F. Steiner.

1782. EITcct of Hull Length-Beam Ratio on the HydrodyuarnlcCharacteristics of Fi@ng Boats In Waves By Arthur W.Carter.

1.783. An Analysis of the Airspeeds and Normal Accelerations ofBoeing B-247 and B-247D Airplanes in (humerc[nlTransport Operation. By Wa]ter G. Walker and Ivan K.Hadlock

1784. Flight Investigation in Climb and at High Speed of a Tmo-Ftlade rmd a lWee-Blade Propeller. By Jerome B.Hammack.

1785. Friction Coef8cients in the Inlet Length of Smooth RoundTubes. By Ascher EL Shapiro and R. Douglas Smith.

17S6. Recommenciat ions for Numericnl Solution of Reinforced-PaneI and Fuselage-Ring Problems. By N. J. Hoff andPlllll A. Libby.

1787. Comparison of the Structural Ediciency of Pmels HavingStraight-Web and Curved-Web Y-Section Stiffeners. ByIVorris F. DOW and Wiiliarn A. Hickman.

17SS. Flight Tests of an Apparatus for Varying Dihedral Effectin FIigM. By William M. KaufPtnan, Allan Smith,Charles J. Llddell, “Jr., and Ge&-ge E. Cooper.

lTSO. Investigation of Aerodynamic find Icing Chnracteristicaof Reeessed Fuel-Vent Cfmflgurations, By Robert S.Ruggeri, Ihve Ton G1ahn, and Vern G. Rollin.

litkl. Inveatiga tlon of Icing Characteristics of Typical Llght-Airplane Engine Induction Systems. By Willard D.Coles.

1791. Corrosion Tests of a Heated Wing Utilizing an Exhaust-Gas-Air Mixture for Ice Prevention. By George H.Holdaway.

1792. Study by the Prandtl-Glanert Method of CompressibilityyEffects and Critical Mach Number for EIllpsoids ofVarious Aepect Ratios and Thk!kness Ratios. By Rob-ert ~. IleSs and Clifford S. Gardner.

1798. In-restigation of Meteorological Conditions Associated vr[thAtrcrsft Icing in Layer-Type Clouds for 1947-48 Winter.By Dwight B. Kline.

1794. Grist-Tunnel Investigation of a Wing Model w[th Sem[-chord Line Swept Back 80°. By Thomas D; Reisert.

1705. Application of Rndial-Equilibrium Condition to Axird-Flow Compressor and Turbine Design. By Chung-HuaW%and Lincoln V?olfenstein.

1706. Theoretlcal Analysis of Oscillations of a Towed CabIe.By William H. Phillips.

1797. A Study of Stall Phenomena on a 45° Swept-ForwardWing. By GeraId M. McCormack and Woodrow L.cook.

179S. Effect of Thicknees on the LateraI Force and Yawing Mo-ment of a Side-siipplng Delta Wing at SupersonicSpeeds. By Kenneth Margolis.

COMMI=E FOR AERONAUTICS

No.1799. On the Flying Qualities of Helicopters. By John P. Reeder

and F. B. Clustafson.1S00. M“minar Mixing of a Compressible Fluid. By Deau R

@apman.ItWI. Vi%d-Tunnel Inwstigat lon of the Spinning Cilarnctvrlstics

of a Model of a Twin-Tnil Lorv-Wing I%mi.mai-Owncr-Type Airplane with LInked and Unliniccd Rudder undA!leron Control& BY Walter J. Kiinar and LawrenceJ. Gal.%

1802. lTind-Tunnel Iuw?stigation of an NACA 63-210 SunispanWing Equipped with Circular Plug Aiicrone rmd a Fuli-Sptm Slotted Flap. By Jack I?ischel.

1808. Downwash in the Vertical and Horlmntal Plmwx of Synl-metry Behind a Triangular Wing in Supersonic Flow.By Harvard Lomax and Lamn Sludcr.

1804. Effect of Longitudinal Stevs on Skipping ClmrnWMstics ofPB2Y-6 I?iying Boat. By R. R. C1ark and W. T. Spm’row.

1S03. R&marks Concerning the Behavior of [he Laminnr Boun-dary Layer in Compressible Flows. By Neal Tetcrvin.

1806. Detiwmh.iation of Plate Compressive Strengths nt Elcra[&iTemperatures. By George J. I.Ielmerl and Wiilinm M.Roberts.

1807. Effects of Ptirtlnl Admission on Pcrformnnce of a GusTurbine. By Robert C. Kohl, Howard Z. Herzig, andWarren J. Whituey.

1808. Method for Evaluating from Shadow or &Mierun Photo-grnphs the Pressure Drag in Two-Dimwmionai or AxinilySymmetrical Flow Phenomena wilh DMacimd Shuck. ByAntonio Ferri.

lS4M. The Method of Characteristics for the Dcterminntlon ofSupersonic I?iow over Rodics of Ruwlut ion at SmaliAngles of Attack By Antonio Ferri.

1S10. Comparison between Prml[cted am-i (Merwd Perfurrnanceof Gas-Turbine Stat or Wnde I%signcd for i?r@-VortexFlow. By M. C. Huppiwt, tind c!luwiw SJa@3regor.

1811. The Longitudinal Stai)iiity of Eirwt!c Swei)t Wings ntSupersonic Spee& By C. W. Prick and R. S. Chubb.

1812 The Application of Airfoll Studies tu IIeiicoiMrr RotorDesign. By F. B. Gnst.afwn,

1S18. A Study of Flow changes Assochltwi with A[rfuil %ctionDrag Rise at Supercrlt ical Siweds. By (-hwald E. Ni!z-berg and Stewart Crandall.

1S14. Effects of Se!wral Design J’arinbles on Turidne-WheelWeight. By Vincent L. LaValie and Merie C. Huppvrt.

1815. OriTompressibilit y Correct ions for Sukmic Flow ovurBodies of Revolution. By Eric Reiesncr.

1S16. Triangular \Vings Cambered and Twisted to Support SiWi-t3ed Dist ribut ions of Lift at Supt’monic Spmls. NYBarrett S. Buldwin, Jr.

1S17. Plastic 13uck1ingof Simply Supported Compressed Pinted.By Richard A. Prhlc anti George J. Helmcrl.

ISIS. Effect of Automa t lc Stabiiizatiou on the Latmal OscillatoryStability of a Hypothetical Air@ne at SupmsonicSpeeds. By Leonard Sterntield. .

1819. The Response of l?ressure hkmsuring Systems to Oscillat-ing Pree.sures. By Israel Tnbaek.

1S20. Strength Analysis of StitYened Thirk l%am Webs. BY L.Ross L-win find Cbxr]es \V. Sandlin, Jr.

182L Ambient Pressure DXermination at High Altitudw byUse of Free-iMolecule Theor~. By Bt!rnard Wicrwr.

1822. Elastic and Plastic Bucikling of Simply Supporlcd MetaliteType Sandwich Plates in Compression. By Paul Seideand Elbrldge Z. Stowell.


No.lS23. The llucklingof Parallel Simply Supported TensIon and

Cmnpressson Members Connected by Elastic ReflectionalS@n@% By Paul Seide tmd John F. Eppler.

l,fi24. Linearized Compresslbl&Flow Theory for Sonic FIfghtSpet}ds. By Mux. A. FIeaslet, Harvard Lomax, and JohnR. Sprefter.

LSZ3. Compressive BuckIing of shnpl~ SupportedPlateswtthLm@tud[nal Stiffeners. BY Paul Selde and llnnuelStein.

1S26.LinearTheorrof BoundaryEffectsin OpenJ1’indTunnelswith F1uiteJet Length. BY S. Katzoff, Clifford S.Gmdner,Leo Dlesemlruck,and BertramJ. Elaenstadt.

lS2i. Matrix Methods for Calculating Canfflever-Bemu Deflec-tions. By Stanley U. Benscoter and 31yron L. Gossard.

MZS. Effect of Furebody Warp on the adrodmamic Qtilftiesof a Hypothetical FtyIng Boat Huringa Hu1lLw@h-BeamRatio of 15. By Arthur~. C’arteraml lrvtngWeinstein.

M29.Dataon the CompressiveStrengthof ‘i5%T6 Aluminnrn-A11oYFlat PmeLswtth Longttud[nalExtrudedZ-Sec-tionStiffeners. BYVi’llltamA. Hickmanand~orris F.Dow.

lS30.TensionPropertiesof .A1uminum~llo~s in the Presenceof stress-llnissrs.I—Effectiof TriaxialStressStateson the Frmturi~TCharacterlst&of 24S-T .Alumtnum~llrIY. By A. ~. Dan%E. L. AuljandG. Sachs.

1.SH.TensionPropertiesof AluminumAlloysIn the Presenceof ~tress-Ra&rs. 11—t2amparisonof Notchstre~Roperties of ?&T, MS-T, and 2X%TS6Aluminum.%WYS.B~E. L. Au4A. W. Dana,antiG. Sachs.

1S32 SnMllBendingand Strete~ingof sandwic~-TypeSheLls.BYEricIWsener.

lS33.~oteaon theFoundationsof theTheoryof SmallDisplac+mentsof OrthotropicShells. By F. B. HiIdebran&E.Relssner,and~. B. Thomas.

16.%.The Influenceof Bkde-wblth Distributionon ProgellerCharacteristics.By ELltottG. Reid.

lS35.Inwstlgat[onat Low S1* of the~ect of AspectRatioandSweepon KollingStablli@Derivati~esof Untaneredwings. BYMes Goodmanand LewisE. Fisher.

1.S36.Initial In~estIgatIonof Carbide-TypeCeramalof W-PercentTitanfrmCm~idePlus 20-PercentCobaltforUse as Gas-Turbine-BladelIateriaL By CharlesAHoffman,G. Mervin~ult, and JamesJ. Gangler.

lSST.Ele-iated-TemperatureCompressiveStress-StrainDatafor 2K+TSMumtnum-ARoySheetandComparisonswithExtruded75S-T6 AluminumMloy. BY Tviuam wRobertsandGeorgeJ. EieimerL

1SSS.Dynamometer-StandInwstigatlonof a Group of MuElers.By Don D. Davisr Jr., and K. R. Czarnecki.

I.SW. Some Theoretkzd Law-Speed Span Loading Chamcteristicsof %ve~t R’Ings in Roll and Sideslip. By John D. Bfrd.

1S40. AnaIyafs of Properties of Foam. By J. W. McBain, SydneyROM, and A. P. Brady.

1S41. Quantitative Stndy of Variations in Ckmcentratlon ofG@cerol and Aerosol GT on Foaming Volume of Otl atRoom Temperatuna By J. W. McBaln and SydneyRoss.

1S42. Control of Foaming by Adding Known Mixturesof PureChemicals By J. W. McBaLn, Sydney Ross, A. P. Brady,and R. B. Dean.


No.U!& Effect of Various Compounds in T?se with Airplane En-

gfnes upon Fonmlng of Aircraft Lubricating GfL ByJ. W. 31cBrdn and W. w. Woods.

ltlLL Surface Properties of Oils. BY J. IV. McBain and James V.Robinson.

1S45. Attempts to Defoam Existing Oils by Processing. ByJ. W. McBain, J. V. RobinsoL W. Vi’.Woods, and L M.Abrams.

M-M. Aeration of AIrcmft Lubricating 011s orer a Range ofTemperature. By Vi’.W. ‘Foods and J. 1’. Robinson.

lS47. Review of ~ulslfted Antlfoams for Aircraft LubricatingOiIs. By W. W. Woods nnd J. V. Robinson.

lWA. FIntter of a UnLform Wing with an Arbitrarilll Pla@dMass According to a D1fferentiaI-Eqnation Ar@afsand a Comparison with Experiment. By Harry LRnnTanand CharlesE. Watkins.

1649.Useof ChamcteristtcSurfacesfor UnsymmetrkalSuper-sonicFlow Problems. By V?.E. hIoeckeL

1650.TheYawing310mentDueto Sldeslipof Triangrdar,TraP&zoi~al,and RelatedPlan Formain SnPersonlcFloTv.BYArtlmrL. JonesandAlbertaMlcsne.

1631.CritIcalShearStressof InflnltelyLong,SimplySupporte!!Platewith~ransverseStieners. BYUanuelStetnandRobertlY. Fralfch.

lS32. Rdnforced Chxndar Cut-outs in Plane Sheets. BY H.Reissner and M. 310rduchow.

1S53. Effect of Increaee in Mterbo@ Length on the Hydrody-

namic Qualities of a Flylng-Boat Hull of High Length-Beam Ratio. By Walter. J. Kapryan and Eugene P.ClemenL

1S54. Approximate Corrections for the IiHects of Compres#bilityon the Subsonic Stability Derivatives of Swept [email protected] LCWk It. Fisher.

lS?i5. Recommended Values of Meteorological I?actolvi to be Con-

1s56.

IS57.

M5s.

lsa.

ls60.

ls61.

IS62.

sidered in the Desfgn of Aircraft Ice-Rerention Eqnip-.-

ruent. BYAlun R- Jones and Wllliarn Lewts.l%eoretkal Study of the Diffusion Constant for Self-Dtf-

fwfon In Metals- By X Leichter.Investigation Wth an Interferometer of the Tnrbulent Mix-

&- of a Free Supersonic Jet. By Paul B. Gooderum,George P. ‘iVocKLand Maurice J. Brevoort.

A Review of AnalyticaI llethods for the Treatment ofFlows with Detached Shocks By Adolf Bnsemmm.

A Method of Calculating a Stability Boundary thnt Defines—

a Region of satisfactory Period-Damping Relationshipof the Oscillatory Mode of Motion. By Leonard Stern-field and Ordmay B. Gates, Jr.

Theoretical Lift and Dnmping in Roll of T&in SweptbackYilngs of Arbitrary Taper and %veep at SupersonicSpeeds. Subsonic Leadtng Edges and Supersonic Trail- ~-ing Edges. By Frank S. Malw?stuto, Jr., Kenneth Mar-goLis, and Herbert S- R1buer.

One-DLmenslonal FIo’ms of an Imperfect Diatomic Gas.By A. J. Eggers, Jr.

A Shnple Method of Estimating the Subsonic IJft andDamping in Roll of Sweptback Wtngs. By Edward C.Pollmmns.

1963. Comparative Strengths of Some Adhesire-Adherent SYS-tems. By N. J. DeLoll@ A’ancy Rucker, and J. R TVier.

H164. Extended Applications of the Hot-Wire Anemometer. ByStanley Corrslm


No.1866. Further Experiments on the Flow and Heat Transfer in rI

Heated Turbulent Alr Jet. By Stanley Corrsin andMahlnder S. UberoL

1866. Spin-Tunnel Inwatigation to DArmLne the Effectireneesof a Rocket for Spin Recovery. By Anehal L Neihouse.

1S67. A Study of Eflects of Heat Treatment and Hot-Cold-Work011Properties of Low-Carbon N-155 Alloy. By J. Vi’.l?reemtm, HI,E. Reyiiokls, D. N. Frey, and A. E mite.

186S. Correlation of Pilot Opinon of Stall Warrdng with FltghtMeasurements of Various Factors Which Produce theWarntng. By Seth B. Anderson.

1869. TVind-Tonnel Investigation of the Opening Characteristics,Drag, and Stabiltty of Several Hemispherical Para~chutes. By Stanley H. Scher and Lawrence J. Gale.

IWO. Free-Space Oscillating Pressures near the Tips of Rotatingl?ropellers. By Harrey H. Hubbard and Arthur A.Regler.

1871. A Mathematical Theory of Plasticity Based on the Conceptof Slip. By S. B. Batdorf and Bernard Budiansky.

1S72. High-LLft and Lateral Control Characteristics o< an NACA6&Z1-6 Semlspan Wing EwO_JPed with plug ml Re-tractable Ailerons and a Frill-Span Slotted Flap. ByJack FLachel and Rnymond D. Vogler.

1S7S. Subsonic Two-Dimensional-Tlow Conditions near an Air-fo[l Determined by” Static Pressures Measnred at theTunnel Wall. By Bernard N. Daley and Lillian ?3,Harem.

1874. Anrdysis of Altitude Compensation Systems for Aircraftcarburetors. By Edward W.. Otto.

1875. On Two-DbnensLonal Supersonic F1OWS. By Stefan Berg-man.

1S76. Calculation of the Aerodwamic Loading of Flexible Wingsof Arbitrary Plan Form and Stiffness. By FrankLin W.Dkderich.

1S77. Effects of Compressibility on Lift and Mad Characteristicsof n Tapered Wing of NACA 64-210 Airfoil Sections upto a Mach Number of 0.60. B~ l?. E. West, Jr. and l’.Himka.

1S78. Study of Unsteady Flow Disturbfinces of Large and SmallAmplitudes Moving through Supersonic or SubsonicSteady P’1OWS.By Robert V. Hess.

1S79. Critical Axial-Compressive Stress of a Curved RectangularPanel with a Central Longitudinal Stiffener. By MurrySchildcrout and Manuel Stetn.

1S80. Determination of Centrifugal-CompreSor Performance onBaste of Static-Preffi-Lii’eMeasurement in Vanelees Dif-fuser. By Ambrose Ginsburg, Irving A. Johnsen, andAlfred C. Redlitz.

1881. Coxnpnrisori of Pltcl@~ Moments Obtained drming Sea-plane Landings with Values Predicted by HydrodynamicImpact Theory. By Gilbert A. Haines.

1ss2. Oxidation Characteristics of Molybdenum Dlsultlde andEffect of Such Oxidation on Its Role as a Solid-FilmLubricant. By Douglas Godfrey” and Erva C. A’etson.

1884. Note on the Accuracy of a lfethod for Rapidly CaIculatingthe Increments in Veloclty about an Ah’foil Due to Angleof Attack. By Laurence K. Loftin, Jr.

1885. Desfgn and Calibrntlon of a Total-Temperature Probe forUse at Supersonic Speeds, By David L. Goldstein andRichard Scherrer.

1886. Ckaupresslve Buckling of Flat Recta&ular hfetalite &vpeSandwich Plates wtth Simply Supported Loaded Edgesand Clamped Unloaded Edges. By Paul Seide.


No.1887. Effect of High Shear Rate on Erosion of Common Ihmrlng

Metals, By Charles D. Strang and Thomas I’. Clark.188S. ReEponse of a Helicopter Rotor to Oscillatory Pitch rind

Throttle Movements. By Paul J. Cm’peuter and IIerberlE Peitzer.

1886. Biaxial Fatigue Strength of 2-IS-T Alnmlnum Alloy. ByJoseph klarln and WilIiam ShclsoII.

1800. The Effect of Torsional k%?xlbility on the Rolling CIIar-acteristics at Supersonic Speeds of Tapered Unswept‘Wings. BY Warren A. Tucker and Rolwrt T.. Nebwn.

NW.. Elastic Buckling of a Simply Supp=mtcd I%tte under aCompressive Stress That J’nries Linearly lu the Directionof Loading. By Charles L1bove, Saul l’erclman, and JohnJ. Reusch.

1892. Position Errors of the Service Airspeed Installntlcms of 10Airplanes. By William Gracey.

1S03. Effect of Centrif ugtil Force on Flutter of Uniform Cantl-Iever Beam at Submdc Speeda wiLh Apfllicatlon tuCompressor and Turbiue Blades. By Alexander MwI-delson.

1804 Boundary-Layer and St~IIIng C’harncteristlcs of t lie NACA6S-609 Airfoil Section. By Donald E. Grmlt.

1S05. EtTect of Aspect Rat in on Undamped Torsional Oscillationsof a Thin Rectangohw Wing in Supersoulc J?Iow. IlyCharles E. Watkins.

1806. Improvement of .kccuracy of Ilalancerl-Pressure Indlcntorsand Development of an Indicator CallbraUng MachinaBy James C. Livengood.

1897. Aerodynamic Properties of Crucifornl-Wing nnd Body Corn.binations at SuMonfc, Trtmsonic and Supersonic SpccdSBy John R. Spreiter.

18Q8. Effect of n 00° Cross Wind on the Take. Off Dishmcc of aLight Airplane Equipped with a Cross-Wind LandingGear. By Seth B. Anderson, Burnett L. Gadclmg, nndWIlllam H. McAvoy.

1S00. TeIoctty Distributions on ArMtrary AirfulLs In ClosedTnnneLs by Conformal Mapping. Ry H. IL 31OSCS.

1000. Preliminary Investigate ion of theUsc of Afterglow forVisualizing Low-Density ComprcsslMc Flows. IlyThomas W. Williams and James M. Benson.

MM. A BIethod for Predicting tile Stability in RN1 of Aut{)-matIcally Controlled Aircraft Based on the I@M-mcntal Determination of thp Chwvwterist [es of anAutomatic Pilot. By Robert T. Jones nud I,wmnrdSternfield.

1902. Appraisal of Method of Flutter Analysis Bawd on ClwcnModes by ~omparisonwith Experimentfor Cases ofLarge Mass CoupUng. By Donnld S. Woolskut andHarry L. Runyan.

1004. Observations of Ichg Comlitkms Encountcrcd in Flight .During 194S. By William Lewis atil Walter 11.Hoecker,Jr.

1005.lMperImentalandThwreticalSLudlesof ArcnSucllonfortheCentrolof theLamh]arBoundaryLayerona l%rousBronze l’+ACA64AO1OAlrfoiL By Dale L. Burrov@AlbertL. Braslow,andh’ealTeterVin.

1006.An AnaMical Studyof the Steady T’WticaI DeSCCnLinAutorotation of Slnglc+Rotor Helicopters. By A. A.Nikolsky and Edward SeckeL

1007. An Analysis of the Transltton of a IIelicoptor from IIovcr-ing to Steady Autorotat ive Vertical Deaccnt. By A, A.Mkoleky and Edward SeckeL

REPORT NATIONAL ADVT.SORY

No.1003. General Algebraic 3fethod Applied to Control AnaIysIsof

Comple-- Engine Typss. By Aaron S. Bokaenbom andRichard Hood.

1909. Effect of Transverse Shear and Rotary Inertfa on theNatural Frequency of a uniform Beam. By Edwin T.~~~zewski.

1910. Shear Buckl[ng of lndnitely Lang Shuply Supported 31et-alite ~ Sandwich Plates By Paul Seide.

191S. Method of Designfng Airfoils with Prescribed VelocityDistributions in Compressible PotentiaI l?lows. ByGeorge R. Ck@ello.

1014. Oxldatfon of T2taniurn Carbide Base Ceramals CantahI-Ing Molybdenm Tungsten, and Cobalt. By M. J. Whft-man and J43. Repko.

1915. Elevated-Temperature Properties of SereraI Tltanfum Car-bide Base CeramaIs. By George C. Deutsch, AndrewJ. Repko, and lVillfam G. IXdrnan.

1017. An Analys[s of the Relatfon betvieen Horizontal Tempera-ture Ym’fattens rind Maximum Effective Gust Yelocttfeafn Thunderst~rms. By K Press and J. K. Thompson.

101% CorreIatfon of Phystcal Properties of Ceramic Materialswith Resistance to Fracture by ThermaI Shock. ByIV. G. Lidman and A. R. Bobrowaky.

1920. Preliminary Inw3st1gation of Needle Bearings of I%-InchPitch Diameter at Speeds to 17,000 rpm. By E. Fred31acks.

1022. Tw&Dimenaioual Instigation of Five ReIated NACAAfrfoil SectIons Desfgned for Rotating-Wing Aircraft.By Raymond F. Schaefer, Laurence K. Loftin, Jr., andElmer A. Horton.

1922. Boundary-Layer and Stalling Characteristics of the NAOA6-LUM6AirfoU Section. BY George B. McCullough andDonaId E. Gault.

1024. Estimation of the Damping in RoII of Wtngs through theNormal FIight Range of Lfft Coedicient. By Alex Good-man and G1enn H. Adair.

X130. An Analysts of the Effect of Lift-Drag Ratio and StallingSpeed on Landing-FIare Characteristics. By J. C!alrinLowll and Stanley L@on.

1031. Design Method for Tvio-Dimensional Channels for Com-pressible How with Application to Hfgh-Solidf~ Cas-cades. By Sumner AlperL

lfJ35. 31ethods for Determining Frequency Response of Engfnesand ControI Systems from Transient Data. By MelvinE. LaVerne and Aaron S. Boksenbom.

1937. A l?llght Investigation of the ISITectsof Ccon~ressibfIity onApplied Gust Loads. By E. l’. Binckleg and Jack Funk.

193& 31echanfsss of Frtilure of High Nickel-Alloy Turbojet Com-bustion Lfners. By John IV. Weeton.

IiMl. Attainable Circulation of AtrfoHs in Cascade. By ArthurW. QoIdstein and Artur 3.fager.

104S. Investigation of Bonding between Metals and Cersm!cs.l—PW2ke1,Cobalt, Iron, or Chromium with Boron Car-bide. By H J. Hamjian and W: G. Lidman.

1031 Method of Determhing Conditions of Maximum IiMicienmof an Independent Turbine-Propeller Combination. By3farcus l?. Heldmsnn.

1056.EquilibriumOperatfngPerformanceof W-Flow TnrbojetEngfnesby bfeanaof idealized~almfs. By John C.s~ders and Edwmdc. chap~

19.S0.Effectof Forebodywarp andincreaseinAfterbodyLengthon theHydrodwmmtcQnaIitiesof a F&iW-BoatHa ofHfgh Length-BeamRatio. BYWalterJ. KaPryan.

.

COMEWI?TEE FOR AERONAUTICS 55

TECHNICAL 31EMOIMNDUMS

Large amounts of the material translated from the Germanare parts of two regular series of reports. Reference wilI bemade to these series of German reports by abbrerlationa dednedas follows :

ZWB-Zentrale f i.lr Wiasenschaftliches Berichtswesen der Lnft-fahrt forschung des Generallnftzeugmeisters (German CentralPublication Ofiice for Aeronautical Reports).

FB-Forschun@erIcht (Research Report).lJM-Lintersuchrmgen und ?Jitteflnngen (Reports and Memo-

randa).

h-o.It6L

IJw.

U.96.

IK)!3.

1221.

WE.

1223.

Em-L

Lwz.

Km6.

120i.

I-209.

Wfnd-TnnneI Tests on Various Types of Dive BrakesMounted fn Proximitr of the Leading Edge of the Wtng.By Bernardino Lattanzi and Erno Bellante From Rela-zione Tecnica h-o. 10: Mintstero dell’ Aeronautlca Dire-zfone Superiore Studl ed IMperienze, 1 DM.sIon+S&zt-

.

one Aerodfnamica, Guidonia, December 1942.Force- and Preesure-Distribution Measurements on Eight

Fuselages. By G. Lange. From ZWB, FB 1516, @t_ 2A104L

Nonstationary Gas FLow in Thin Pipes of Tarfable CrossSection. By G. Guderley. From ZWB, FB 17M Ott-22, 1942.

Compression Shocks In Tvio-Dtmensfonal Gas Flows. ByA Buaemann. From Tortrtige aus dem Gebelte derAerodynamic und wnvnndter Gekeite, Aachen, 1929,pp. 16%169.

Rotation in Free Fall of Reetangalar Wings of EIongatedShape. By PauI Dupleich. From Publications Scien-Wiques et Techniques du Secretariat d’Etat a l’AvtatfoqNO. 176, l&!l.

On mind Tunnel Tests and Computations Concerning theProbIem of Shrouded PropelleE By W. Krifger. From2Pi’7B,FB 1049, Jun. 21, 10M.

The Compressible Flow Past Varfous Plane Profiles NearSonic Velocity. B. GGthert and K. K KawaIkL From~B, TAf 1471, Jan. 6, l*-.

Some New Problem on SheI1s and Thin Structures. ByV. S. VIasoY. From: Izvestia Akademli h’auk, 1O-K,No.1, pp. 27%3.

Exact Calculation of Laminar Boundary Layer in Longi-tudinal F1OW Over a FM Plate with HomogeneousSuction. By Rudolf Iglisch. From Mathematical In-stitute of the Technfcal Academy Brannachwelg,Schriften der Deutschen Akademie der Lufffahrtfor-Schung, vol. SB, No. 1, 1944.

Systeraatlc ln~estfgationa of the Effects of Plan Formand Gap Between the Fwed Surface and Control Sur-face on Simple Flapped Wings. By Gtithert and Rther.From zWB, FB 63224, Feb. 10, 1940.

The Theory of Plasticity in the Case of Sfmple LoadingAccompanied by Strain-Hardening. By A. A. Ilrnsbin.From Prikladnaya 31atematika i Mekhanika, VOL 11,No. 2, 1947, pp. 293-296.

Calculation of Counterrotatfng Propellers. By F. Gfnzel.From zWB, li’B 1752 Jan. 25, 1943.

Experimental Study of Flow Past Tnrbtne BIades. By EEckert and K. v. Vietinghoff-ScheeL From Vorabdrttckeaus Jahrbuch 1942 der deutschen Luftiahrtforschtmg, ‘6. Lfeferung, pp. 2-10.


No.1210. Development of Spoiler Contiols for Remote Control of

Flying Missiles. BYG. Ertit midM. Kramer. FromZWB, FB 1717,Jan. f3,194.3.

J.211.The Charncterk?ticsMethodAppliedto stationaryTwo-DhnensionalandRotationallySymmetricalGasFlows.By F. I?feifferand ~. bfeyer-K6nig.FromZWB, FB1581,~lm. 20, 1042.

1212.On theTheoryof theLavalNosale. By S. V. Falkovich.FromPr[kladnayaldutematikai hfekhanika.Vol. 10,No. 4, 1646, pp. 503-612.

1213. Gas Motion in a Loial Supersonic Region and Conditionsof Potential-Flow Breakdown. By A. A. NikoIMrii andG. I. Taganov. From Prikkidnaya Matematika i Mek-hanika Vol. 10, No. 4, 1!346,pp. 4S-502.

1214i Jet Diffusion in Proximity of a Wall. By D. Kilchemann.From ZWB, UM 8037, Dec. 81, 1943.

1215. Flow Pattern in a Converging-Diverging Nozzle. By KL@watitsch and W. Rothstein. From Jahrbuch 1942 derdeutachen Luftfahrtforechung, pp. I 01-102.

1216. An Approximate Methodfor Calculationof the UminarBoundaryLnYerwith Suctionfor Bodiesof ArbitraryShape. By H. schlic~ting From AerodynamischesInstitut der TechnischenHochschuleBrauneclmeig,Bericht48/13, June 12, 1043.

1217. Lecture Series “Boundmy Layer Theory”. Part I—Lam-inar Flows. By EL SchliciMng. (Given during WinterSemester 1041/2 at Luftfahrtforschungeanstalt HermannG6ring, Braunschw%ig) From ~B, pp. l-lkkl.

l%% Lecture Series “Boundary Layer” Theory”. Part II-Tur-bulent Flowe. By H. ScLdichting. (Given during Win-ter Semester 1941@ at Luftfahrtforeehungeanstslt Her-rnann G!king, Braunschweig ) From ZWB, pp. 154279.

COkLMITTE”EFOR AERONAUTICS

No.1219. The Influence of the Application of Power During Spin

Recovery of Multiengined Airplfines. 13y P. IIBhlcr.From ZWB, FB 1586, Feb. 12 1!)42.

1224. Lame’s Ware Functions of the Fillipsoid of Revolution.By J. Meixner. I?rom ZWB, FR 1952, June 1044.

122S. !Wet Report on Three- and Stx-Component 31@asurcmentson a Series of Tapered Wings of Small Atipcct Ratio,(Partial Report: Trapezoidal Wing) By I.unge/Wncke,J?rom ZWB, UM 1023/1, Sept. 15, 1943.

1229. Heat Transmission iu the Boundary Luyer. By L. litKalikhman. From Prikladnaya Mnt(!mat!ka i }ickha-nika, Vol. 10, 1946, pp. 44%474.

1230. Effect of the Accelemtfon of ElongntwI Bodies of RevohEtion Upon the Resistance in a Comprceslble I~lo!v. ByB’. L I?rankl. From Prikladnaya Mni ~mulika i Mekhnn-ika, Vol. 10, No. 4, 1046, pp. 521-624.

1288. CoiiEriimtion to the Prob!em of Flow at High Speed. 13yC Schmieden and K IL KawNki. From LiIienthal-G@eellechaft fiir Luftt%hrtforschung, Report S 13/1, 1942,pp. 40-66.

1234. Coiiiiutation of Thin-Wnlled Prismatic ShNla. By V. Z, ‘-Vlasov. From Priklndmlya Mtitemntika i Mekhonlklt,VOL8, No. 6, lP&t.

123S.Two-Dlmemional Whlg Theory In the Snpcraonic Rmgc.By FL H8n1. FromzWB, FB 1008,Jan.6, 1944,

1240.Airfoil?demurementsIntheDVLIIlgl@~eedWnd Tunnei(2.7-XleterDiameter) By B.08thert, FromLilientlml-GesellscMftfilr Luftfahrtfmschung,Report 166, PP.6-16.

1249.Susceptlbll!t~to meldingcracking,\VeldingSvm=itiv~ty, “-Susceptibilityto Welding Seam Cracking,md Teatltfethodefor theseFailures. By K. L, 7@~cn, FromZWB,Luftfahrtforachung,Vol.20,No.S/0,Oct.10,l%i3,pp.231-241..

Part II—COMMITTEE ORGAAVZATION AND MEMk?ERSllIP

The act of Congress approved March 3, 1915, estab-lishing the Natiomd Advisory Committee for Aeronau-tics (U. S. Code, Supplement II, title 50, sec. 151), asamended by act approved March 25, 1948 (PubIic Law549,80th Cong.), provides that the Committee shall con-sist of 17members appointed by the President, and shallinchde “t w-orepresentati~es of the Depttrtment of theAir Force; two representatives of the Department ofthe h’avy, from the officein charge of navfd aeronautics;two representatives of the Civil Aeronautics Author-ity; one representative of tl~eSmithsonian Institution;one representatire of the United States Weather Bu-reau; one representative of the Nationtd Bureau ofSttindards; the Chairman of the Research and De~elop-ment Board of the h’ational 31i1itary Establishment;and not more than se-iertother members selected frompersons ttcquainted with the needs of aeronauticalwience, either civil or military, or slcilled in aeronau-tical engineering or ite allied sciences~t These latterseven members serve for terms of five yettrs. Therepreaentntives of the Government organizations servefor indefinite periods. MI members serve as such with-out compensation.

The retirement of 31aj. Gen, Edward M. Powem fromthe Air Force resulted in the termination of his mem-bership on the Committee, and uncler chtteof March 22,1949,the President appointed Maj. G-en.Donald L. Putttthen Brigadier General), Director of Reswmch andDevelopment in the Air Force, to succeed GeneralProvers as a member of the Committee.

Effectire December 1, 194S,the President reappointedMr. William Little-wood and Dr. Theodore P. Wright,members from pritate life, for” 5=~af terms.

Because of his resignation t-tsAssistant Secretnry ofCommerce for Aeronautics, Hon. John R. Alison hassubmitted his resignation as a member of the h’ACArepresenting the CiviI Aeronautics Authority, and his.mccessoron the Committee has not yet been appointed.

In mcordtmce -withthe regulations governing the or-~wnization of the Committee as approved by the Pres-ident, the Chtiirmannnd Vice Chairman are ekcted nn-nually, as are also the Chairman and Vice Chairmanof the Executive Committee.

On October 20, 1949, Dr. Jerom8 C. H~m~akerwasreelected Chairman of the N’ACA and of the ExecutiveCommittee, and Dr. Alexander Wetmore and Dr. Fran-cis W. Reichelderfer were reekcted lTice Chairman ofthe hTACA and Vice Chairman of the ExecutiveCotnmittee.respectively.

C03LMI’I’TKE ON AERODYNAMICSDr. Theodore P. Wrtght, Comell Unlveraity, Chahman.Capt. Walter S. Dieh~ U. S. N., Bureau of Aeronautics, Vice

Chairman.3daj. Gem Henry B. SayIer, U. S. ~, OfEce of the Chief of

Ordnance.COL O. J. RitIand, Afr 3fat&ieI Command, U. S. L F.COLGeorge F. Smi@ Air Mat&iel Command, U. S. A. F.Rear Adm. F. L Entwtstle, U. S. N., Bureau of Ordnance.?&E F. A. Londe& Bureau of Aeronautics, Department of the

Navy.Mr. Harold D. Hoekstra, Civil ~erontmtks Administration.Dr. Hngh L. Dryden (es ofllclo).Mr. FIoyd L. Thompson, NACA Langley Aeronautical Laboratory.Mr. CarIton Biolettl, NACA kes Aeronautical Laboratory.Mr. Paul S. Baker, Chance Vought Aircraft, United Aircraft

Corp.Mr. Otto E. Kirchner, tierlcan AfrIines, Inc.31r. Gro-ier Loenfng.Mr. L. E. Root, Rand Corp.Mr. George S. Schairer, Boeing Ah’pIane Co.Dr. WIII1am R. seam Cornell University.Dr. Theodore Ton Karman, Calffomia Institute of Technology.Mr. Fred E. Weick, Agricultural and Mechauicnl CoUege of Texas.

Mr. Milton B. kes, Jr., Secretary.

!%bcommittee on Flnid MeehanicsDr. Clark B. lfflllkim, California Institute of Technology,

Chahrnan.Dr. Frank L. Tattendorf, Air 31at6rieI Command, U. S. Air

Force.Mr. ELH. Kent, Ballistic Research Laboratory, Aberdeen Proving

Ground.Capt. Walter S. DiehI, U. S. N., Bureau of Aeronau~ic&Mr. George V. schl~estett, Office of Navttl Research, Department

of the Xavy.Dr. R. J. Seeger, Na~aI Ordnance Laboratory.Dr. G. B. Schubauer, National Bureau of Standards.Dr. Carl Kaplan, NACA Langley Aeronautical Lab&atory.Mr. John Stack, NACA Langley Aeronautical Laboratory.hr. Robert T. Jones, W4CA Ames AeronautkaI Laboratory.Mr. W. G. T%centi, NACA Amee Aeronautical Laboratory.Dr. John C. Evmrd, h’AC.l Lewis Plight Propulsion Laboratory.Dr. William Bollay, North tierican Aviatio% Inc.Dr. Francis H. Claussr,JolmsHopkfnsunlrerstt~.Pro~HowardT. Emmons,[email protected]. HansLlerimann,~alifomlaInstituteof Technology.Dr. C.C.Lin,}iaamchusettsInstltnieof Technolo&v.Dr. JtllllarnR Sears,C’ornellUniYersitr.

JIr.E.O.Pearson,Secretary.

.%hcommitteeon High-Speed.4emdynamicsW. L. E. Root,RandCorporation,Chairman.Mr.H, L. ~nderaan,.Mr31at&ielCoraman&U. S. Air ForeCOLJ. A. Gibbs,U. S.A. F.,A1rllat&ieICommand.Mr. C. L. Poor, LII,BrIHisticRe.wmchI..&wmtories,Abwdeen

ProvtngQronnd.Comdr.SFdneYS. Shet’bY,U.S. A’.,Bureauof ~eronautica.

57


Mr. William H. Miller, Bureau of Aeronantic& Delnutment ofthe h’aW.

Mr. Oscar Seldman, Bureau of Aeronaut its, Department of theNavy.

Mr. Andrew VazaonyI, Navtil Ordnance Test Stat Ion, Inyokern.Dr. Hugh L. Dryden (ex officio).Mr. Robert R. GIlruth, NACA Lnng!ey Aeronautical Laboratory.Mr.JolmStack,NACALatigieyAeronautlcrdLaboratory.Mr.H.JultanAllen,~AC.4AxuesAeronautIcalLt_tboratory.Mr.AbeSllverstein,NACALewisFli~hKPro@slon Laboratory.Mr.IrvingL. Ashkena~,NorthropAircrttft,Inc.Mr.BenedictCohn,[email protected]. Paul C. Emmons, Bell Aircraft Curp.Mr.JohnG. Lee,UnitedAircraftCorp.Mr.HaroldLusMn,Dou@asAircraftCo.,Inc.Prof. John R. Markham, Massachusetts Institute of Technology.Mr. Allen El.Puckett, California Instttute of Technology,Mr. WllJlam C. Schoolfteld, Chance Vought Aircraft, United Air-

craft Corp.Mr. H. A. Storms, North American Aviation, Inc.

Mr. E. O. Pearson, Secretary.

Subcommittee on Stability and Control

Capt. Walter S. DIehl, U. S. N., Bureau of Aerounutlcs, Chairman.Mr. MeIvln Shorr, Air Mat4rfel Command, U. S. Alr ForceMr. Gerald G. Kayten, 13Weau of Aeronautics, Department of

the Navy.Dr. George L. Shue, Naval Ordnance Laboratory.Mr. John A. Carran, C1vfl AeronautIce AdmfrdatratiomMr. Thomas A. Harris, NACA Langley Aeronautical Laboratory.Mr.HarryJ. WetLNACAAmesAeronauticalLaboratory.Mr.Ph[lipA. Culman,LuckheedAircraftCorp.Mr.PercyHalpert,SperryWroscopeCo.,inc.Mr.E. R. Heald,Dou@asAircraftCo.,Inc.Mr.VV.F. M1llfken,Jr.,CornellResearchI?oundatlon,Inc.Mr.DaleD.?&m’&NorthAmericanA\-IatIon,Inc.Prof. C. D. Perkins, Prfnceton Untvemity.Prof. Robert C Seamans, Jr., Massachusetts Institute of Tech-

nology.Mr. Charles Tilgner, Jr., Grumman Aircraft Engineering Corp.

Mr. Bernard Maggin, Secretary.

Subcommitteeon InternalFlowDr. Stewart Way, Westinghouse Electric Corp., Chairman.Bfr. James El.DeRemer, Air Mat&?lel Command, U. S. Air Force.Mr. Joseph Flatt, Air Mat&tel Command, U. S. Air Force.Mr. Parker M. BartIett, Bureau of Aeronautics, Department of

the Navy.Dr. K. F. Rubert, NACA Langley Aeronautical Laboratory.Mr. E. A. Mossman, NACA Ames Aeronautical Laboratory.Mr. John 0. Sanders, NACA Lewis lWght Propulsion Latmratory.Mr. Henry H. Hoadley, United Aircraft Curp.Dr. W. J. ODounell, Republlc Avlatlon Corp.Mr. Otto P. Prachar, Alltson Divfsion, General Motors Corp.Mr. Ralph H. Shlciq Ocmsolldated Vuitee Aircraft Corp.Mr. A. ?& O. Smith, Douglas Aircraft Co., Inc.Mr. hf. A. Sulkhi, North American Aviation, Inc.

Mr. Bernard Maggfn, Secretary.

Subcommittee on Propellers for Aircraft

Mr. George S. Schairer, Boeing Airplane Co., Chairman.Mr. Dttnlel A. Dickey, Air hfat6riel Command, U. S. Air Force.Mr. AnthonyF. Dernbach,Air Mat&lel Command, U. S. Alr

Force.Mr. Gerald L. Desmond, Bureau of Aeronautics, Department of

the Navy.

cohikfITTEE FoR ~RONAUTIC%

Mr. Iva~ H. Drfggs, Bureauof Aeronauth%,Depar(mt!ntof the -Navy.

Mr.JohnC.Morse,CivilAeronautlca~dminlstration.Mr. Engene C. Draley, NACA Lm@ey Aeronautical Laborrttot’y.Mr. Robert M. Crane, NACA Ames Aeronautical Laboratory.Mr. George W. Brady, Curttss-Wright Corp.Mr. Frank W. Caldwell, United Aircraft Corp.Mr. Thomas B. Rhines, Hamilton Shtndard Pr@e11er6, UnltMl

Aircraft Corp.Mr. R A, Anderson, Secretary.

Subcommittee on SeaplanesMr. Grover Luening, Chairman.Mr. H. L. .%ndersou, A1r Mzttgriel CommanQ U. S, A1r Force.Mr. J. M. HeraId, Air 31atCrlel Command, U. S. Air Force.Capt. Walter S. Dlehl, U. S. N., Bureau of Aet’OnfiWiCS.Mr. F. W. S. Locke, Jr., Bureuu of Aeronautlc& Department Of

the Navy.Commander Henry E. McN&?ly,U. S. N., Naval Air Test Center,

Patuxent.Rear Adm. C. O. Kell, U. S. N., David W. Taylor Model Iktsin.Coriunander Donald B, MacDiarmid, U, S. C. G., U. S. Coafh

Guard Air Station, San Diego.Mr. Albert A. VolImecke, Civil Aeronaut[ca AdmlnlatratIcm.Mr. John B. Parkinson, NACA Langley Aeronautical Laboratory.Prof. K. S. hf. Davidson, Stevens Institute of Teclmology.Mr. Leo Geyer, Grumman Aircraft Englneerlng Corp.Mr. J. D. Pierson, The Glenn L Martin CO.Mr. E. G. Stout, Consolidated Vultee Aircraft Corp.Mr. Willtarn R. Ryanr Edo Corp.

Mr. J. W. Elwrt, Secretary.

Subcommittee on HelicoptersMr. Richard H. Prewitt, Prewltt Aircraft Co., Chairman.Mr. Bernard Llndenbaum, Air Mat4r1eI Command, U. El. Air

Force.Mr. P. A. Simmons, Air Mat6r1el Command, U. S. Alr Force.Mr. Raymond A. Young, Bureau of Aeronautics, Department of

the Navy.Commanier James W. Klopp, U. S. N., Bureau of Aeronautic%Commander Frank A. Erldmcm, U. S. C. G., Rotary Wing Devel-

opment Unit, Coast Guard ALr Station.Mr. R. B. MaIoy, Civil Aeronautics Administration.Mr. B. L Springer, Civil Aeronautics Administration.Mr. R 0, Dlngeldeln, NACA Langley Aeronautical Labortttury.Mr. F. B. Guatafson, NACA Langley Aeronautlctd Laboratory.Mr. Michael E. Gluhareff, Sikorsky, Aircraft, Unit~d A[rcrtift

Corp.Mr. Charles EL Kaman, The Kaman Aircraft Corp.Mr. Bartram Kelley, Bell Aircraft Corp.Mr. Itene H. Miller, Massachusetts Institute of Technology.Afr. Robert R. Osboru, BfcDonnell Aircraft Corp.Mr. F. N. P1aseckl, Pku+scki HelicorIter Corp.

Mr. R. A. Anderson, Secretary.

SpFcial Subcommittee on the Upper AtmospftercDr. Harry VVexler, U. S. Weather Bureau, Chairman,Brig. Geri. Donald N. Yates, U. S. A. F., Air Weather Service.(%L Bedamin G?.Holzman, U. S. A. F., Office, Deputy Chief of

Staff for Bfat6rIe1, Department of the Air Force.Col.B.farcellusDuffy,U.S.A. l?.,81dOthElectronicStatIon,t2am-

bridge.Dr. MarcusD. O’Day,41i5SdAir ForceBaseUnit,A3fC,Cam-

bridge.Capt.WalterS.DiehLU,S.N.,Bureauof AeronautlcaDr. Har~eyHall, Bureauof Aeronautics,Departmentof the

Navy.

REPORT NATIONALADVISORY

Capt. Horrar(l~. Orville,U. S. & Office,Chiefof NavalOpera-tlolm

Dr.HouerE.Newell,Jr.,~wmlResearchLaboratory.Dr. lY. & Brcmbacher,~atiourdBureauof Standartls.Mr.JVIlliaraJ. O’Sullimn,~ACALangleyAeronauticalLalIom-

tory.Dr.L.V.Berkner,CarnegieInstitutionof M%@ington.Prof. C.~. Gartlel~Cornell~niveraaty.Dr.B.Gutenlwrg,CalifornlaInstituteof Technology.Prof.BernhardHmwwit~NewYorkI_k&wraity.Dr. JosephKaplan,~nirersit~of Caltforni&Dr. C.L. Pekeris,PrInvetm~ntvemity.Dr.J. & VanMien,JohnsHopkinsT_?niyersity~pP1iedPh@cs

Laboratory.Dr. FredL. ~h[pple, HarvardCn!versity.Dr.O.R JVnlf,CaliforniaInstituteof Technology.

Mr.O.J.Deters,secretary.

COM.MIYTEEOX POWER PWTS FOR AIRCR4FTMr.RonaIdM. Haze&MIkon Dtvisio&GeneralMotorsCorp..

Chairman.Prof.E S. Taylor,Massachusettslnstttuteof Technology,V&

chairman.COLR. J. Mtnty,U S. A. F.,Air Mat&lelCommand.COLRalphL.~aasell,~. S.A. F.,Alr31at&telCommand.Uipt.A. L.Balr&U.S.~., Bureauof Aeronautics.Mr.StephenRolIe,Ci\”ilAeronauticsAdmlnlstmtlon.Dr.HughL Dryden(ex otRcIo).Mr.CarltouKemper,?JAC~LewisFilghtPropuNlonLaboratory.Mr.L. S. Hobbs,UnitedMrcraftCorp.Mr.\YIU1auM.HoIaday,Socony-VacunmOtlCo.,inc.Prof.JosephH. Keenan,MassachusettsInstituteof Twlmology.Mr.R P. Kroon,~esttnghouseElectricCorp.Mr.~illlam C.Lawrence,American Ahlines, Inc.Mr. Norman L. 310che~Westinghouse Blectric Corp.Mr. D. F. Warner, GenemI Electrlc Co.31r.Raymond W. Young,Wright Aeronautical Oorpq Divfalon of

Curtisa-Wrtght Corp.Mr. Robert E. LtttelL secretary.

Subcommittee on AIrmaft FueIsMr. W. M. Holaday, Socony-Vacunm Oil Co., Inc., Ohatrman.Mr. E C. Phillips, Mr 3fat6riel Command, IL S. Air Forc&Commander R. J. HoyIe, U. S+N., Bureau of Aeronautics.Mr. DonaId B. Brooks, Rwearch and Development Board.Mr. Kenneth S. Cnllorq Civil Aeronautics Administration.Dr. L. C. G1bbo~ NACA Lewis Flight Propnlston Laboratory.Dr. D. P. Barnard, Standard Oil Co. of Indiana.Mr. A..J. BlackWood, Standard Oil Development Co.Mr. S. D. Heron,EthylCorp.Dr. J. BennettHII1,Sun011Co.Mr.C R. Jwhnsor&S~ellOilCo.,In&Mr.FloydG.Dougherty,AlltsonDlrtston,GeuemlMotorsCorp.Dr. ~. E Kuhn, The Texris Co.

Mr. HenryE.~lqulst,Secretary.Subcommitteeon Combustion

Dr. Bernard Lewis, Eiureauof Mines, Chairman.Mr. Garret t L Wander, Air Xfat@riel Comman% U. S. Air Force.Lt. Comdr. C. C. Hoffman,U.S.~., Bureauof ~erontiutks.Mr.ErnestF. Ftock,JSatlonalBureauof Smndards.Dr.M’alterT. Olson,~~C.ALewisFlightPropulsionLaboratory.Mr.EdmundD. Brown,Pratt& ll%ttneyAircraft,UnitedAtr-

CraftCorp.Mr.FloydG. Dougherty,AlltsonDivisio&GeneralMotorsCorP.Dr. JosephO. Hirschfelder,Untversitgof 11’bwonetn.

CO~EE FOR AERONA~ 59

Mr. Robert B. Lewis, Wright Aeronautical Corp., Divts[on ofCmtiss-Wrtght Corp.

Dr. Juhn P. Long’well, Standard Oil Development Co.Mr. T. E Myers, North American Aviation, Inc.Mr. A. J. Nerad, General Electric Co.Dr. Robert A’.Pease, Princeton Unirersdty.Dr. Martin SummerfleltL California Institute of Technology.Mr. E. P. Walsl& Westinghouse EIectric Corp.Prof. Glenn C. W1tliarns, Massachusetts Institute of Technology

Mr. Henry E. Alqulst, Secretary.

Subcommittee on Lubrication and WearMr. Arthnr F. Ilndervioo& General Motors Corp., Chairman.Mr. Edgar A. Wolfe, Ah Matt%iel Comman~ U. S. Air Force.Lt. Comdr. Leo W. Mrdlane, U. S. N., Bureau of Aeronautic&Dr. William Ziman, h-aval Re.warch Laboratory.Mr. John H. Collins, Jr., NACA Lewis Flight Propulsion Labom-

tory.Dr. O. Beec& SIMII Development C%.Prof. John T. Bnrweu Jr., Massachusetts Institute of Technolo~.Mr. C J. MCDOWSII,AI1faon DMafon, General Motors Corp.Mr. Joseph Palanllch, Cleveland Graphite Bronze Co.Mr. ELM. PhflIfps, Geneml Electric Co.Mr. Earle A. Ryder, Pratt & Whitney Aircraft, United Aircraft

Corp.Mr. CLEL Stockdale, ‘iVesttnghouse Electric Corp.Dr. Haakon Styri, SKF Industri+ Inc.Dr. John C. Ztmmer, Socony-Vacuum OiI Co., Inc.

Mr. William H. _iVoodward, secretary.

Subcommittee on CompressorsProf, Howard W. Emmons, Harvard University, chairman.Mr. Ople Chenoweth, Air 31at6riel Comman& U. S. Alr Forca3fr. Karl Guttmann, Bureau of Aeronautics, Department of the

Navy.Mr. John R. Erwfn, NACA Langley Aeronautical Laboratory.31r. Robert O. Bull- NACA Lewis Flight Propntsion Labora-

tory.Mr. Rudolph Bh’mann, DeLaval Steam Turbine C!o-Mr. Walter DoLl, Pratt & Whitney Atrcraft, Urdted Aircraft

Corp.Mr. R. S. Ha~ General Electrlc Co.Dr. W. R. Hawthorne, 31machnsetts Institute of Technology.

.

Mr. Gordon E. HolbrooQ Allison Division, GeneraI Motors Corp.Mr. Bernard J. 3.Ie%ger,Wright Aeronautical Corp., Dlvtsion of

Cnrtias-Wrtght corP.

Mr. Arnold H. lleddi~ Westinghouse Electric Corp.Mr. Allen C Staley, Chrysler Corp.Prof. George F. W%lIcenns, Johns Hopkins University.

Mr. Donald J. Tod& Secretary.

Subcommittee on Turbines

Mr. Arnold EL Reddlng, Westinghouse EIectric Corp. Chairman.Mr. Ernest C Simpsom Air 31at6rieI CommanQ U. S. Air Force.Commander Frank K. Slason, U. S. N., Bureau of Aeronautic.Mr. John V. Becker, NACA Langley Aeronautical Laboratory.3fr. Oscar ‘A’.Schey, NACA Lewts Flight Propulsion Laboratory.Mr. Earl L. Auyer, General Electric Co.Mr. Jack C. Fetters, Allison Divkdorq General Motors Corp.Mr. Donald S. HerseF, Pratt & Whitney A.Ircraf~ United Atr-

craft Corp.Mr. W. XL S. Rtchards, Wright Aeronautical Corp., DIvtston of

Curtfas-Wrtght Carp.ProL Ascher H. Shapiro, Massachusetts Inatltute of WehRoIogy.

Mr. DonaId J. ‘llodd, Secretary.

60 REPORT NATIONALADVISORYCO=~EE FOR “AERONAUTICS

Subcommitteeon PropuKlon-SystemsAnalysisProf. Joseph H. Keenan, Massaclmaetts Institute of Technology,

Chairman.Mr. Opie Chenoweth, Air Mat&lel Command, U. S. Air Force.Mr. Ivan H. Driggs, Bureau of Aeronautlce, Department of the

Navy.Dr. Kennedy F. Rubert, NAOA Langley Aeromutfcal Labora-

tory.Mr. Benjamin Plnkel, NACA Lewis E’ltght J?ropnlsion Labo~-

tory.Mr. Dimltrius Gerdan, Allison Division, GeneraI Motors Corp.Mr. Charles A. Meyer, Westinghouse Electric Corp.Dr. W. J. O’Donnell, ReiiibIic Aviation Corp.Mr. Erold F. Pierce, Wrtght Aeronautical Corp., Division of

Curtias-Wright Corp.Mr. Perry W. Pratt, Pratt & Whitney Aircraft, United Aircraft

Corp.Mr. El.E. Stoeckty, General Electric t%.Dr. Maurice J. Zucrow, Purdue Uni~-e&dty.

Mr. Robert O. Dietz, Jr., Secretary.

Subcommittee on Heat-Resisting MateriaIs

Mr. Norman L. Mochel, Westinghouse E1ect~ie Corp., Chalrumn.Mr. J. B. Johnson, Air Mat@rlel Command, U. S. Alr Force.Lt. ComcLC. C. Hoffman. U. S. N., Bureau of Aeronautics.hfr. Nathan E. Promlsel, Bureau of Aeronautics, Department of

the Navy.Mr. Irvin R. Kramer, Oltlce of Naval Research.Mr. W. N. Harrison, NatIonal Bureau of Stakdards.Mr. John H. Collins, Jr., NACA Lewis Flight Propulsion Labora-

tory.Mr. W. L Badger, General Electric Co.Mr. Howard C. Cross, BatteRe Memorial InstItute.Mr. Ruwell Franks, Unfon Carbide & Carbon Corp.Mr. Arthur W. F. @weu, Alllson Dfvtaion, General Motors corp.Prof. Nicholas J. Grant, Massachusetts Institute of Technology.Dr. Marcus A. Grossmanri, Carnegie-I1linols SteeI Corp.Dr. Gunther Mohllng, Allegheny Ludlum Steel COWMr. R. H. TMelemann, Pratt& WMtney Aircraft, United Aircraft

Corp.Mr. William H. Woodward, Secretary.

COMMITTEE ON AIRCRAF’i’ CONSTRUCTION

Dr. Arthur E. Raymorid, Douglas Aircraft Co., Inc., Chairman.Mr. R. L. Templin, Aluminum Co. of America.Lt. COLErnest N. Ljunggren, U. S. A. F.. Air Mat4r1el Command.Commander Cedric W. Stirllng, U. S. N., Bureau of Aeronautics.Nr. Albert A. Vollmeck% Civtl Aeronautk?e Administration.Dr. Hugh L. Dryden (ex OIRC1O).Dr. Henry J. E. Reid, NACA Langley Aeronautical Laboratory.Mr. Carlton Biolettl, NACA Areas Aeronautical Laboratory.Mr. Don O. Benson, Northwest Airline% Inc.Prof. Raymond L. BIsplhwhuff, Massachusetts Institute of Tech-

lloIogy.Dr. Emereon W, ConIon, University of Michigan.Dr. C. C. Furnas, Cornell Aeronautical Laboratory.Dr. Alexander A. Kartveli, Republic Aviation Corp.Mr. George Snyder, Boeing Airplane Co.Mr. Charles R. Strang, Douglas Aircraft Co., Inc-Dr, Clyde Williams, Battelle Memorial Institute.

Mr. 11’ranklyn‘W.PhilIips, Secretary.

Subcommittee on Aircraft Structnrea

Mr. Chaules R. Strang, Douglas Aircraft Co., Inc., Chairman.Mr. Joseph KeIla~, Jr., Air Mat6riel Command, U. S. Air Force.Mr. IfLH. Selnvartz, Air Matdrlel Command, U. S. Air Force.

Commander Willfam C. Dunn, U. S. N., Bureau of Aeromutice.Mr.O1lfl!ordw. Hurley,Bureauof Aeronautlca,DcParLmentUf

theNavy.Mr. William T, Shuler, Civil Aeronuutlce Admlnlstratlon.Mr. Samuel Levy, National Bureau of Standards.Dr. Eugene E. Lund@et, NACA Langley Aeronautical I.abora-

torj.Prof. W. H. Gale, Maesachwet ts lnst itute of Twhnology.Dr. Nicholas J. HofT,Brooklyn I?olytcchnic Inst Itute.Mr. Jerome F. McBreart y, Lnckheed Aircraft Curp.Mr. Frances Me Vay, Republlc AvlatIon Corp.Mr. John H. Meyer, McDonnell Aircraft. Corp.Mr. R. L. Templin, Alumhmm Co. of Amcrlca,

Mr. James C. McCulloctI, Secretary.

Subcommittee on Vkation and Fluttrr

Prof. Raymond L. Bisplinghoff, ?Jtwarwhusetta Institute of Tech.noIogy, Chairman.

Mr. Benjamin SnMg, Air Matdriel Command, U. S. .41r Force,Capt. Walter S. Diehl, U. S. N., Bureau of Aeromiullea.Mr. Douglas T. Egbcrt, Bureau of Aeronautics, DcpttrtmcnL of

the Navy.Mr. Robert Rosenbaum, Civil Aeronautics Adminlstrat [on.Mr. 1. E. Garrtck, NACA Langley Aerouautlcal Laboratory.Mr. A1lxwt Erkkson, NACA Ames Aeronautical Laboratt.try.Mr. SamueI S. .Manson, NACA LewSa F!tght Propulsion Lnbma-

tory.Dr. J. M. Frankhmd, Chance Vought Aircraft, Unitc(l Aircraft

Corp.Mr. E. l?. K[nnaman, Boeing Airplane Co.Mr. H. Erich Ntetsch, The G1eun L. Martin Co.

Mr. Clotaire Woo& Secretary.

Subcommittee on Aircraft LondaMr. George Snyder, Boeing Airplane Co., Chairman.Mr. Joseph H. Barrington, Air Mat&!iel Command, U. S. Afr

Force.Commander Norman J. KleIss, U. S. N., Burenu of .icronnulka.Mr. Robert F. Speaker, Bureau of Aeronautics, Department of

the Navy.bfr. Edward L Ryder, CN1l Awmutut ice Admintatrathm.Mr. Richard V. Rhode, NACA Langley Aeronnutlcal Laboratory.Mr. .Manley J. Hood, NACA Ames Acronnut lcnl Laboratory.Mr. John G. Borger, Pan American Airway% Inc.Mr. l?. D. Jew’ett, The Glenn L. Mnrtln Co.Mr. William C. Schoolfleld, Chance J’ought Aircraft, United

Aircraft Corp.Mr. K. E. Van Every, Douglas Aircraft Co., Inc.

Mr. Clotaire Wood, Sccretau.

%bcommittee on Aircraft Structural MatcrinL+

Dr. Clyde Williams, Battelle Memorial Iuditute, Chuirtnan.Mr. J. B. Johnson, Air Mat6r1eltlmm~nd, U. S. Afr FmcaMr. Jaines E. SullIwm, Bureau of Aeronautics, Department of

the Navy.Dr. Gordon M. Kline, National Burenu of Standards.Mr. Willinm F. Roeser, National Bureau of Standards.Mr. Stanley Yagtela, CiVIlAeronautic Admhdslration.Dr. S. B. Batdorf, NACALnrtgleyAeronautical I.aboratory.Mr. Frank B. Bolte, North Amcrlcan Aviation, Inc.Mr. Edgar H. DIx, Jr., Aluminum Co.of Anwrhw.Dr. MaxweR Gwmamer, Cfmuegie-Illinols Steel Ckmp.Dr. J. C. bfdlcma]d, The Dow Chemical Co.Mr. L. J. Marlmardt, Forest I?ruducts Laboratory.Dr. Robert F. Meld, Carnegie Instlt utc of Technology.Mr. T. E. Piper, Northrop Aircraft, Inc.

Mr. Franklyn W. PMIIiPs,SecretnrY.

REPORT NATIONALADVISORY

COMMITTEE ON OPIXMTING PROBLEMS

~[r. Wllllam Llttlewoo~ A.mefimn AlrHne$ kc., cha~r~n.Dr. Francis W’.Hek’helderfer,U. S. Weather Bureau, Vice Chair-

man.Maj. Gen. Wiiiiam H. Tnnner, M1lltary Air Transport Service.COLFrederick R. Dent, Jr., U. S. A. F., Air Mat4rie1Command.COLJ. Francis Taylor, Jr., U. S. A. F. Air Mrtt6riel Cmnmand.Commander G. A. Hatto~ U. S. N. Bureau of Aeronautics.Mr. George IV. Hak.leman, Civfi Aeronautics Admlnlstratlon.31r.DonaId M. Stuar4 CIYUAeronautics Admtnletration.Dr. Hugh L. Dryden (~ officio).Mr. Melvin N. Gougk NACALangley Aeronautical bborator~.Mr. Richmd V. Rhode, NACALangley Aeronautlcai Laboratory.Mr. Lewis A. Rodert, NAC!ALewis FiI@t Propulsion Laboratory.Mr. P. R. BassetL Sperry tl~roscoce Co.,Inc. Division of Sperry

Corp.Mr. ?&G. Beard. American AlrI1nes,Inc.Mr. CharIes E’roes@ Eastern Alr L[nes, Inc.Capt. HzroId E. Gray, Pan American World Airways.Mr. Ben O. Howard, Coneoiidated Vnltee Aircraft Corp.Mr. Louis R. Koeprdck, Transcontinenmi & Western Air, IncMr. Jerome Lederer.Dr. Ross A. McFarlan& Harvard School of Public Health.Mr. W. C. Mentzer, United Air Lfn~ Inc.

Dr. T. L K. Smull, Secretary.

Subcommittee on Meteorological ProblemsDr. Francis W. Re[chekierfer, U. S. Weather Bureau, Chairman.Brig. Gen.Donaki N. Yates, U. S.A.,A1rWeather Service.COLMarcelIus Duffy, u. S. A F., 31~h El@r~n!c station, csm.

brldg~Capt. Howard T. OrvIiie, U. S. X., OtEce,Chief of NavaI Opers-

tions.Mr. George M. FrencQ Cfvii Aeronautics Board.Mr. Robert W. Craig, CIvii AeronautIce Administration.Mr. Delbert M. L[ttle, U. S. ‘i’i’eatherBureau.Dr. Ross Gunn, U. S. ‘Weather Bureau.Dr. Harry Wexler, U. S. Weather Bureau.Mr. PhiI1p Donely, A’ACALangley Aeronautical Laboratory.Dr. H. R. B~ers, Unlw+raIty of Ctdmgo.Mr. AlIan C Ciark, Pan American WorId AIrwa~31r. Joseph J. George, Eastern Ab! Lines, Inc.Prof. H. G. Houghton, Maseachwtts Iwsritute of Technology.Prof. Athelstan F. Spiihaus, University of Minnesota.

Mr. Donald B. Taimage, Secretary.

Subcommittee on Icing Problems

Mr. R. L. McBrien, United Air Lines, Inc., Chtilrman.Mr. Bernard Chasman, Air Mr@riel Command, U. S. Afr Force.Mr. James E. DeRemer, Air Mat6riel Command, U. S. Air Force..Mr.Duane 31.Patterso& Air l.iat~riel Comman& U. S. Air Force.Mr. Parker M. Bartlett, Bureau of Aeronautic, DeRttrtment of

the Navy.

COMXJTTEE FOR AERONAUTICS 61

Mr. H. C. Sonta& Bureau of Aeronauti~ Department of theKavy.

Mr. Stephen Rolie, Chii Aeronautics Adminietratlon.Mr. B. C. Haynes, U. S. Weather Bureau.Mr. Aiun R. Jones, XACA Ames Aeronautical Laboratory.Mr. VWlson H. Hunter, BiACA Lewis Flight Propulsion Labora-

tory.Mr. Arthur A. Brown, Pratt & WMtney Nrcraft, United Aircraft

Corp.Dr. Wailace E. Howel~ Mount Washington Observato~.Mr. Robert L. Lfnforth, Boeing Airpiane Co.Mr. Da~id A. North, American Airifnes lialntenance Base.

—.

Mr. W. W. Reaser, Douglas Aircraft Co., InaMr. O. E. Rodgers, Westinghouse Electric Corp.Mr. Vincent J. Schaefer, GeneraI Electric Co.

-—

Mr. Donald B. Tahnage, Secretary.

Subcommittee on Aircraft Fire Pre~ention

Mr. Lcwis A. Rodert, NACA Leviis Flight Propulsion Laboratory,Chairman.

Mr. HowCmdA. Klein, Air Mat@riel Command, U. S. Air Force.Mr. Howard EL NoF~ Air 3iat&’iel Command, U. S. Air Forc&JIrLj. C. H. llcConuelI, U. S. A. F., Flying Safety DIvisio~

Langley AFB.Mr. Charles W. Shubrirt, Bureau of Aeronauti@ Department of

the Navy.Mr. John M. ChamberialU CiviI Aeronautics Board.Mr. Harvey L. Hansberry, Ci\-li Aeronautics AdministrationMr. David L. Posner, Civil Aeronautics AdminMration.Mr. John A DicL~n, National Bureau of Standards.Mr. E. IL Barber, The Texas Co.Mr. John G. Borger, Pan American Airways, Inc.Mr. Alien W. Dailas, Air Transport Association of America.Ml. HaroId E. Hobeu American Airihv?s, Inc.Mr. CLR. Juhnson, Sheii 011 Co., Inc.Mr. Raymond D. Keliy, Utdted Air Lines.Mr. GayIord W. Newton, Boeing Airplane Co.Mr. Ivar L. Shogra& Dongias Aircraft Co., Inc.Mr. Imn Storey, Jr., Iackheed Aircraft Corp.Mr. CIem G. Trimbtic~ Corneii Research Fonndatlon, Inc.

Mr. R[chard S. Cesaro, Secretary.

INDUSTRY CONSULTING COMMITTEE

Mr. John 11 Xorthro~ Northrop Aircraft, Inc., Chairman.Mr. Robert EL Gross, Lockheed Aircraft Corp., }-ice mairmag.Mr. Lawrence D. Beil, Beii Aircraft Corp.Mr. Lynn L. Boiiinger, The Aeronautical Research Foundation.?Lr. EL M. Homer, United Aircraft Corp.31r. E. l’. Rickentmcker, Eastern Air Lhs, Inc.Mr. Earl F. Slick, Siick Airways, Inc.Mr. Dwane L. Waliace, Cessna Aircraft 0.

Dr. T. L. K. SmulI, Secretary.

Part III—FINANCIAL REPORT

Approprff7tion8 for the @cal gear i’949.-Funda in the follow-ing amounts were appropriated for the Committee for the fiseaIyear 1940 trt the Independent OftIces Appropriation Act, 1949,approved April 20, 1943, and the Second Dettciency AppropriationAct, 1949, ttpproved June 23, 1649.

Salaries and expenses ..__._-. —---__---—-— $3s, 557,000Printtng and bindlng-—__— =-_-=-----L— - --95,000Construction and equipment of Laboratory facilities:

Lsngley Aeronautical Laboratory ----------- 4, lSS, 630Ames Aeronautical Laboratory___————— 870,300Lewts Flight Propulsion Laboratory __________ 6, Ml, 030..

Total approprlatlons_—_- 48,652,000

The amount appropriated for construction and equipment oflaboratory facilities includes $2,143,000 for liquidation of theObligations incurred under the contract authority provided inthe appropriate [on act for the fiscal year 1948. The remainder,$7,857,000, is available fcmobligation during the fiscal years 1949tmd 1050. Additional contract authority was provided for con-struction and equlwneut of laboratory facilities in the amountof $18,200,000 in the 1940 act, for obligation dm’lng fiscal Years1049 and 1950.

Obligations incurred agalnat the tlacal year 1049 appropriationsare listed below. The figures shown for salarles and expensesinclude the costs of personal services, travel, transportation,cor.umunication, utlllt y services, contractual services, supplies,and equipment.

Salaries and expenses:~NACAHeadqutirters----—___——_ --. —-- —-- $763,159Langley Aeronautical Laboratory-_ --__-—__ 1(3,238,616Ames Aeronautical Laboratory--- -- 6,133,977Lewis Flight Propulsion Laboratory---———- 14,303, 56SResearch Contracts-educational institutions--- 603,172Transfer to National Bureau of Standards_——_— 175,000

Printing and binding, all activities-———---- 04, 8%Construction and equipment of laboratory facilities:

Langley Aeronautical Laboratory-——----- 2,397, 6ssAmes Aeronautical Laboratory—-———- 359,364Lewis Flight Propuldon Laboratory_-_— 3, 6S3, 839

Total obIfgationa-——--___—— 44,673, 77R

Unobligated balances:Salaries and expenses—_-—_——————— 310, MMPrinting and binding.-------—-—-— 3.0sConstruction and equIpment--.-— 3, 65s, 009

Total approprlations— 43, WE, Ooo

The folloWng obligations were also incurred against the flscnlyear 1949 additkmtil contract authority prm%k’d fur const ruc-tion and equipment of laboratory ftwilltics:

LangIe~ Aeronautical Laboratory___—_—_— $3,554,372Ames Aeronautical L~hratory__—-——-— 395,622Lewis Filght Propulsion Labm’story _______ 3,333,478

TotaI obligations, tlscnl yettr 10NI---------- 7, ?&?,97!?,Total avallable for obligation, meal year l!MO---- 10,414,022

Total authoriztition_- l& 2qo, 000

Appropriations for the fiscal Vcar l!)50.-Funds in the follow-ing amounts were nppro~rlated for the Committee fur the decalyenr 1950 in the Independent 0f3rcs Appropriate ion Act, lWii,approved Augnst 24, 1049:

Salaries and espenses-- $X3,Ooo,OtMConstMction and equipment of Iaburatury facili-

ties:Langley Aeronaut ical Laborutory---_—--- 4,706,200Pilotless Aircraft Research Stat hm ----------- 771, OcioAxnes Aeronautical Laboratory---_-— Oco,OooLewis Fllght Propulsion Laboratory-—— ----- .3,502, ~

Total appropriations— -— 53,000,000

The $10,000,000 appropriated for construction ~nd equipmentof Laboratory facilities tncludea $7,277,200 for llquldnllon ofobllgat ions incurred pummmt to tbe contract nuthorizatlon con-tained in the appropriation act for the flacal year 1049. Theremainder, $2,722,800 is available for oblign tion during fiscalyears 19~Mand 1031 in accordance with the a~proprtatlfin actfor fiscal year 1%0. Additional contract aulhorlty for con-struction and equipment of laboratory facilities in the amountof $10,000,000 was also Rro~ided in the 1930 ncti fur Ohligatlcmduring the fiscal years 1050 and 1051.

62