AERONAUTICS

NINETEENTH ANNUAL REPORT “

OF THE

ONAL ADVISORY COMMITTEEFOR AERONAUTICS

NAT

1933

INCLUDING TECHNICAL REPORTS

Nos. 441 to 474

UNITEDSTATESGovERNMmwPRINTING

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LETTER OF SUBMITTAL.

To THE CONGIZESSOF THE UNITED STATES:Pursuant to the act of March 3, 1915 which established the National Adviso Committee for Aeronautics,

I submit herewith the Nineteenth Anmxd Report of that Committee for the b (X7 year ended June 30, 1933.The attention of the Congress is invited to the o e- pages of the Committee’s report giving the ma-or

i dreasons for the recent improvements in the speed an efficlenc of airplanes for military and civil uses. heprincipal underlying cause of this remsxkable progress has been d e efficient functioning of the National AdvisoryCommittee for Aeronautics in coordinating and planning for the research needs of aviation, civil and military,and in conducting the necessary fundamental scientific researches to serve the needs of all encies.

I concur in the Committee’s opinion that the continuous prosecution of fundamen 3 research in aero-nautics is essential to the national defense and to the future of ti transportation upon a sound economic basis.

FEANKLIN D. ROOSEVELT.THE WHITE HOUSE,

January 1%,1934.III

LETTER OF TRANSMI’I”TAL

NATIONAL ADVISORY COW~EE FOR AERONAUTICS,Wmh{n@on, D.(7., Decemkr 16, 1933.

ME. PEESIDENWIn compliance with the provisions of the aot of Con ess a

I have the honor to transmit herewith the Nineteenth %lmu&aroved March 3, 1915 (lJ.S.C., title 50, sec. 153),

Aeronautics for the fiscal year ended June. 30, 1933.port of the National Admsory Committoe for

The past year has to an unprecedented degree witnessed the application by the Arm ~ the Navy, and theaircraft indust of the cumulative results of years of fundamental research oonducted by

3&s Committee to meet

the needs of “ “tary and civil aviatiom It saw greater improvement in the speed of mrcraft and in economy ofoperation than has been made in any dngle year since the war.

~her speeds have introduced new problems into a heavily crowded progrsm of investigations. The Conwmittee IS energetkall~ proseout@j a comprehensive research progrsm to serve all needs, snd is coniident thatcontinued support of Ii%work will continue to yield results of immeasurable milit

%value and of economic value

qeatl in excess of its annual appropriations. The independent status of ther

ommittee hss been the mostwtal aotor in its success and is essential to its continued efficient functioning.

Respectfully submittid.JOSEPH S. AMES, Ch&nuzn.

THE PRESIDENT,The White Howe, Wwhington. D.C.

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TECHNICAL REPORTS

PageNo. 441. A Flight Investigation of the Spinning of the NY-1 Airpfane with Varied Mae-eDistribution and other MOCMIX.

tiom, and an Analysis Based on Wiid-Tunnel Tests. By Nathan F. Schudder ----------------------------No. 4.42. A comparison Between the Theoretical and Measured Longitudinal Stability Characteristics of an Airplane.

By Hartley A. Sou16 and John B. ~eatiey -----------------------------------------------------------No. 443. Premum-Distribution Measurements on the Hull and Fins of a l/40-Scale Model of the U.S. Airship AIwon. By

Hugh B. Fmeun--------. ---- _-__ ---------------------------------------------------_---------:---No. 444. Wind-Tunnel Research Comparing Lateral control Devices Particularly at High Anglw of Attack. VI-Skewed

Ailerons on Rectangular ‘i%@. By Fred E. Weick and Thomas A. Hati -------------------------------No. 445. Working Charts for the Deterrrdnation of the Lift Distribution Between Biplane WingS. By Paul Kuhn -------No. 446. Airfofl section Chamcteristics aa Affected by Protubemnces. By Eastman N. Jacobs ------------------------No. 447. Static Thrust of Airplane Propellem. By ‘Wrdtw S. DieM ------------------------------------------------No. 448. Improved Appamtus for the Measurement of Fluctuations of Air Speed in Turbulent Flow. By W. C. Mook,

Jr., and H. L. Dryden ------------------------------------------------------------------------------No. 449. Wing Characteristka as Affected by Protuberances of Short Span. By EaatmanN. Jacobs and Albert Sherman---No. 460. The Calculation of Take-Off Run. By Walter S. Diehl-----------__-- -----------------------------------No. 451. The Dmg of Two Streamline Bodies as AiTeeted by Protubemncea and Appsmdages. By Ira H. Abbott --------No. 462. General Potential Theory of Arbitrary Wing Sections. By T. Tkodomen and I. E. &rfick------------------

— No. 453. The Esthnat[on of Maximum Load Capacity of Seaplanes and Flying Boata By Walter S. Diehl--_”_---------No. 454. Photomicrographic Studies of Fuel Spmys. By Dana W. Lee and Robert C. Spnwr ------------------------No. 455. Penetmtion and Dumtion of Fuel Spmys from a Pump Injection System. By A. M. Rothrouk and E. T. Marah-No. 456. The Aerodynamic Forms and Moments Exerted on A Spinning Model of the NY-1 Airplane aa Measured by the

Spinning Balance. By M. J. Barnber and C. H. Ztiemn -------------------------------------------No. 457. Maneuvembility Investigation of an 03U-1 Observation Airplane. By F. L. Thompson and H. ~. Kirachbaum--No, 458. Relative Loading on Biplane Wings. By Walter S. Diti -------------------------------------------------

%- No. 459. The N. A.C.A. Full-Scale Wind Tunnel. By Smith J. De Fmnce ------------------------------------------No. 460. The Chamcteristics of 78 Related Airfoil Sections from Testa ~ the Variable-Density Wind Tunnel. By Eaatman

N. Jacobs, Kenneth E. Ward, and Robert M. Ptietin ------------------------------------------------\No. 4(31. Interfenmce on an Airfoil of Finite Span in an Open Rectangular Wind Tunnel. By Theodore ‘Theodo~en-----No, 462. Tern%of Nacelle-Propeller Combination in Varioua Positiona with Reference to W’ings. III-Clark Y wing—

Various Radial-Engine Cowlings— Tmctor Propefler. By Donald H. Wood -----------------------------No. 463. The N.A.C.A. High-speed Wind Tunnel and Tests of Six Propeller Sections. By John Stwk-----------------No. 464. Negative Thrust and Torque Characteristics of an Adjustable-Pitch Metal Propeller. By Edwin P. Hartmen---No. 466. Determination of the Theoretical Premmre Distribution for Twenty Airfoils. By I. E. &mick----------------No. 466. Aircmft Power-Plant Instruments. By Harcourt Sontag and W. G. Bmmbatier ----------------------------No. 467. The Experimental Determination of the Moments of Inertia of Airplanes. By Hartley A. SOUM and Marvel P.

MMer --------------------------------------------------------------------------------------------No. 468. ,I!he Interference Between Struts in Various Combinations. By David Biermann and William H. Herrnstein, Jr--No. 469. Increasing the Air Charge and Scavenging the Cleamnce Volume of a Compression-Ignition Engine. By J. S.

Spanogle, C. W. Hioks, and H. H. Fotier -------------------------------------------------------------No. 470. The N. A.C.A. Tank-A HighSpeed Towing Basin for Testing Models of Seaplane Floats. By Starr Truscott--No. 471. Performance of a Fuel-Injection Spark-Ignition Engine Uding a Hydrogenated Safety Fuel. By Oscar W. Schey

and Alfred W. Yo~g ------------------------------------------------------------------------------No. (472. Wind-Tumel Tests on Combinations of a ‘iVfng With Ffxed Auxiliary Airfoils Having Various Chords and Pro13ks.

By Fred E, Weick and Robert S=dem ---------------------------------------------------------------No. 473. Strength Tests of Thin-Walled Duralumin Cylindem in Compression. By Eugene E. Lundquist-_.-----------No. 474. Nomenclature for Aeronautics. By National Advisory Committee for Aemnautim ---------------------------

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NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

lD3ADQUARTBlWjNAVYBUUDINQ,WASHINGTON,D.O.

LABORATO=, LANOLEYFIELD,7A.

Created by aot of Congmm approved Maroh 3, 1915, for the supervision and dirmtion of the soientffiostudy of the problems of flight. Its membership was inoreased ta 15 by aet approved March 2, 1929. Themodem are appointed by the I?reddentj and serve as suoh without compensation.

JoenPHS. _, Ph.D., Chairman, CHARLESA. hNDBKRQH,LL.D.,Preeidenk Johns Hopkins University, Baltimo~ Md. New York City.

DAVID‘iV. TAYLO~D. Eng., Vice Chairman, WILLLA~ P. MCCRACKEN,Jr., Ph.B.,IVashington,D-C. W’ashingtoh, D.C.

CHARLESG. ABBOT,SC.D., CHARLRSF. MARVIN,SC.D.,&cretary, SmithsonianInstitution. Chief, United States Weather Bureau.

Lmc.AN J. BRIQQS,Ph. D., HENRY C. PRAIIT, Brigadier General, United States Army,Director, Bureau of *dards. Chief, Mat6riel Division, Air Corps, Wright Field, Dayton,

ARmmm B. CooK, Captain, United Stat- Navy, Ohio.Assiitant Chief, Bureau of Aeronautics, Navy Department. EUQDNEL. VIDAL, C.E.,

BENJAMJND. FOULOW Major General, United Stak Army, Direator of Aeronautics, Department of Commerce.Chief of Air Cap, War Department. EDWARDP. WARNK~ M.S.,

HARRYF. GUQGENHEUWM.A., Editor of Aviation, New York City.Port Washington, Lang Island, N.Y. ORVILLEWRIGHT,SC.D.,

ERNDSTJ. KrNG, Rear Admiml, United States Navy, Dayton, Ohio.Chief, Bureau of Aeronautics, Navy Department.

GnormEJW. lkmmh Dirmior of Aeronautical Reaca.rch

Jom F. VIcroBY, Secrctav

J3mmY J. E. ItmD, Enginetr in Charge, LanglqI Memorial Acronauticul kboratorgq tingl~ Field, Va.

JOEN J. Irm, Technical Amistant in Etwopc, Paris, Frame

TEC~CAL COMMITTEES

AKRODYNAMI= PROBLRMSOFAIENAVIGATIONPOWRRPLANTSFORAIRCRAFT AIRCRAFTACQD~

MATRRIAISFORAIRCRAFT INVENTIONSANDDHGNS

Coordinatwn of Re-searvhNeeds of Milikny and Civil Aoiaiion

Preparation of Research Programs

~OMtiOll of Problume

Bwention of Dupltktim

Con&ikration of Inventions

LANGLEY MEMORIAL AERONAUTICAL LABORATORY OFFICE OF AERONAUTICAL INTELLIGENCE

LANGLEYFIRLD,VA4 WMHINGTON,D.C.

Uniiled conduct for all agenciu of Collection, clasaiication, compilation,scientific rwearoh on the fundamental and dimamma. tion of scientific andproblems of flight. technied information on aeronautics.

Vnx

NINETEENTH ANNUAL REPORTOF THE

NATIONAL ADVISORY COMMITTEE FORAERONAUTICS

WASHINGTON,D. C., Nooember 14, 1933.To the (bngrese of the Untied tia.ke:

In accordance with the act of Congress approvedMarch 3, 1915, which established the National Ad-visory Committee for Aeronautics, the Committeesubmits herewith its nineteenth annual report for theiimal year 1933.

Continued progress,-It is gratifying to the Com-mittee to report that the past year was notable aswitnessing the greatest advance in airplane perform-ance rmd efficiency accomplished in any single yearsince the Great War. This is largely the cumulativeresult of yews of organized scientific research con-ducted by this Committee and of the practiwd applica-tion of the results by the Army, the Navy, and theaircraft industry.

Result of sound governmental policy.-In the opinionof the Committee aeronautiwil development in theUnited States is certainly abreast, and, in certain par-ticulars, in advance of the development in any othercountry. This is the result of long-continued soundgovernmental policy in supporting fundamental aero-nautical research. It began with legislation 18 yearsago which established the National Advisory Commit-tee for Aeronautic as an independent Governmentcmtablishment “to supervise and direct the scientificstudy of the problems of flight,” and has been con-tinued through generous appropriations to this Com-inittee. Thus one central governmental organization,with the active cooperation of the War, Navy, andCommerce Departments and of the aircraft industry,supplies the research needs of aviation. By this policyof coordination, remdts of greatest value to aeronau-tics are obtained with prevention of duplication andwaste. Supplementing this policy, there is effectiveapplication of the results of the Committee’s researchesin the experimental and development laboratories ofthe &my and Navy.

Comprehensive reseamhes serve all needs.—The research programs of the Committee are formu-lated largely by the various technical subcommitteeswhose membership embraces all governmental agenciesconcerned. A large part of the Committee’s rcswrchprograms consists of specitic requests of the Army and

Navy air organizations. The latter depend upon theCommittee for the scientific study and investigation offundamental problems necessary for the improved de-sign of military and naval aircraft. Aircraft manufac-turers and operahm also rely upon the Committeo forfundamental data, and the Committee broadens itsmilitary and naval researches to obtain as much funda-mental information as possible in order to meet theneeds of civil and commercial aviation. In this theCommittee is assisted by the cooperation of the Aero-nautic Branch of the Department of Commerce andby an annual conference with representatives of theaircraft industry, held at the research laboratories atLangley Field, Va.

Facilities for fundamental research.-The Commibtee has recognized its responsibility in shaping the prog-ress of aeronautics and, with the far-sighted supportof the Comgress, has anticipated the research needs ofaviation and developed at Langley Field, Vs., the best-equipped aeronautical research laboratory in the world.This one central laboratory is lmown as the LangleyMemorial Aeronautical Laboratory and is operatedunder the single and direct control of the Committee.The fundamental researches approved by the Com-mittee are conducted at that laborato~, where there .are combined under ideal conditions facilities for labo-ratory investigations and for researches on airplanesin flight. Much of the equipment there is original andingenious and permits investigations that give resultsnot obtainable in any other country. The develop-ment of this laboratory represents in itself an accom-plishment in which the Congress and the countrymay take pride, for the excellence of its product hasgained for the Unitid States an advantageous positionamong the progressive nations in the development ofaeronautics.

Itesulta of researoh,-speed is still the most impor-tant single factor in incmwing the relative importanceof aircraft for national defense and in extending theiruse for commercial purposes. Primarily as a directresult of the Committee’s researches there have beengreat increases in speed and efficiency during the pastyear, which have opened a new era in the developmentof both military and commercial aircraft. The in-

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2 REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

. crease in the speed of multiengined airplanes, militnqand commercial, from 1932 to 1933 has approxinmtec40 to 60 percent with practically the same engimpower. This development is one of the outstandingcontributions of the Committee, the major factors being:

(1) The National Advisory Committee for Aewnautics engine location and cowling. (The results oithe cowling research were published in 1928. Theresulk of the engine location research were issuedconfidentially to the Army, Navy, and industry in1930, and were kept cordidential until 1932, when thefirst American airplanes embodying the principleshad been d&gned and actually constructed.)

(2) The development by the Army, the Navy, andthe industry of reliable retractable lan~~ geara.

(3) Increased horsepower with same size and weightof engines, invol~~ increased revolutions per minute,higher compression ratio, improved fuels, and im-proved cylinder cooling.

(4) The development by the Army, the Navy, and theindustry of satisfactory controllable-pitch propellem.

(5) The development by the Committee of new andmore efficient wing sections.

(6) Improved stremnlhQ and use of wing flaps,assisted by the Committee’s researches.

A great increase in the l@h speed of an airplanewould ordinarily be accompanied by a dangerousincrease in its landing speed. This presented aproblem of devising means of increasing the lift anddrag of the wing to permit landing at a lower speed,without attendant loss of control. Increased safetyin the operation of aircraft will resmlt primarily fromreduction in landing speeds with retention of adequatecontrol. Toward this end the Corm@ttee has con-ducted researches on a number of high-lift devices,some of which are now in use. . Othe~ under inve&-gation hold promise of further progress in retainingadequata control at lower landing speeds.

Researoh pays,—It is e~ntial. to nation~ defe~eand to American air commerce that the United States

strive to keep abreast or ahead of other nations in thetechnical development of both military and commer-cial aviation. The researches of the Comniittee leadto material improvement in the performance, eiliciency,and safety of aircraft. No money estimate can beplaced on the value of superior performance of air-craft in warfare, for aerial supremacy is quite likelyto be ultimately decisive of a war; nor can a moneyestimate be placed on the indeterminable savings inlife and proper@ due to improved safety in the opera-tion of both military and civil aircraft. The value indollars and cents of improved efficiency in aircraftresulting from the Committee’s work can, however,be fairly estimated. For example, the result.s of sixresearches completed by the Committee within thelast few years, when applied to airplanes equal innumber to those in use during 1932, show that savingsin money alone will be made possible in excess annuallyof the total appropriations for the Committee sinceits establishment in 1915.

In the opinion of the Committee the continueddevelopment of aviation is vital to our nationalsecurity and defense. Aviation is also becoming nnincreasingly important factor as an agency of trans-portation. Its continued development holds possi-bilities for the growth of a large industry, creatingnew sources of wealth, new fields of employment, cmdnew outlet9 for the energies of the American people.The Clmnnittee is of the opinion that the most es-sen-tial fundamental activity of the Govemrnent in aero-nautics is the continuous prosecution of well-organizedmd coordinated scientific research. Ckmtinuous fun-damental research is absolutely vital in the lad annly-is, as it underlies the effectiveness of the air arms ofthe natiomd defense, the stability of the aircraftindustry, and the prospect of ultimate success of airbmsportation upon a sound economic basis. TheZommittee accordingly recommends continuation of.ts work in the fields of pure and applied research on~hefundamental problems of flight.

PART I

REPORTS OF TECtiCAL COMMITTEES

In order to carry out effectively its principal func-tion of the supervision, conduct, and coordination ofthe scientific study of the problems of aeronautics, theNational Advisory Committee for Aeronautics hasestablished under the executive committee four maintechnical committw+-the committees on aerodynam-ics, power plants for aircraft, materials for aircraft, andproblems of air navigation-and under these comrnhtees, eight subcommittees. These technical committeesprepare and recommend to the executive committeeprograms of research to be conducted in their respectivefields, and as a result of the nature of their organiza-tion, which includes representation of the variousagencies concerned with aeronautics, they act as coor-dinating agencies, providing effectively for the inter-change of information and ideas tid the prevention ofduplication. The membemhip of these committeesand subcotittees is listed in part II.

The committees on aerodynamics and power plantsfor aircraft have direct control of the aerodynamicand aircraftmngine research, respectively, conductedat the Committee’s laboratory at Langley Field, andof special investigations conducted at the Bureau ofStandards. The greater part of the research underthe supervision of the committee on m&erials for air-craft is conducted by the Bureau of Standards. Theexperimental investigations in aerodynsmica, aircraftpower plants, aircraft materials, and air-navigationproblems undertaken by the Bureau of Aeronautics ofthe Navy, the Army Air Corps, the Bureau of Stand-ards, and other Government agencies are reported tothese four committees.

REPORT OF COMMITTEE ON AERODYNAMICS

SUBCOMMITTEE ON AIRSHIPS

In order that the committee on aerodynamics maybe kept in close touch with the latest developments inthe field of airship design and construction and thatresearch on lighter-than-air craft may be fostered andencouraged, a subcommittee on airships has beenorganized under the committee on aerodynamics..

The subcommittee has kept in close touch with theairship investigations under way at the Langley Memo-rial Aeronautical Laboratory: The program of airshipwork at the laboratory includes the study in the full-scale wind tunnel of the forces on a large airship modelut large angles of pitch and of yaw. In cooperationwith the Bureau of Aeronautics of the Navy, the Com-mittee has also obtained information on the speed anddeceleration on the full-size airship Mzcon.

LANGLEY MEMORIAL AERONAUTICAL LABORATORY

LANTXNGSPEED AND SPEED Rncm.—The speed ofboth military and commercial airplanes has increased ‘very markedly during the past year. This increasein speed has been accomphshed partly through anincrease of engine power, but mainly through the re-duction of drag. The low drag, while advantageousin obtaining high speed, is disadvantageous in that itlimits the gliding angle which can be obtained at low “speed, and makes necessary a very long flat approachto a landing. The higher maximum speeds have alsobeen accompanied by a tendency to use heavier wingloadings, and the landing speeds have increased towhat seems to be the practical limit. Under theseadveme landing conditions, devices for increasing themtium lift coefficient and also the drag at the highanglw of attack have been of great interest.

Flap mod&cu.t&nm-The cxmunittee’s work on splitflaps has been continued during the past year. Theseflaps have now been used on several airplanes, eitherin the simple form or in the Alfaro-Zap form, in whichthe flap is moved to the rear as well as deflected down-ward. In response to the demsnd for more detsiledinformation in regard to their aerodynamic effect andin regard to the air loads on the flaps, further tests havebeen made in the 7- by 10-foot wind tunnel. The airloads on t~e flaps have been measured for the purposeof supplying information on which to compute thestructural strength needed and the forces required todeflect them (report in preparation). The results ofthese tests showed that the ditilon of the tot~ lift .between the split flaps and the wing was little affectedby flap deflection in the ordinary fright range, althoughthe division of the total drag was greatly u%ected byflap deflection. The normal-force coefficient was alsogreatly affected by flap deflection, the coefficient forthe flap alone reaching a value of approximately1.40 at the angle of attack and flap deflection formaximum lift.

Another investigation was made in the 7- by 10-foottuunel to determhe the effect on the aerodynamic ‘characterktics of partial-span split flaps located atvarious positions along the wing span (TechnicalNote No. 472). The results showed that as the flap iscut away from the tip, the loss in lift is small at first,but becomes substantial if sufficient flap is removed toallow room for ordinary ailerons. If the flap is cutaway from the center, the loss starts more rapidly,being in the neighborhood of 8 or 10 percent for thecut-out usually found necessary for structural reasons.

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4 REPORT NATIOhTAL ADVISORY COMMITTEE FOE AERONA~CS

Full-scale tests with simple split tips have beenmade with a parasol monoplane both in the full-scaletunnel and in flight, with flaps 20 percent of the wingchord in width extending over the outer 90 percent ofthe wing span. The fubcale lift, drag, and pitching-moment coe5cienta for the airplane were found in thefull-scale tunnel both with the horizontal tail surfacesin place and with them removed (Technical NoteNo. 475). The value of C~_ was increased from1.47 to 2.09 by deflecting the flap, the stalling anglebeing the same in both casea. These results agreewell with the model resulti obtained in the 7-by 10-foottunnel with regard to the effect of the flap. Thecompukd landing speed of the airplane was reducedfrom 51 miles per hour to 41.9 miles per hour by theuse of the flaps.

The flight tests, the model tests in the 7- by lo-foottunnel, and the full-scale wind-tunnel tests all showedthat the control force required to displace a simplesplit flap is undesirably great. A series of wind-tunneltests is now in progress to study the effectiveness ofvarious methods of reducing the hinge moments ofthese flaps.

A year ago the highest lift coefficient obtained bythe Committee with any kind of flap device was 3.17,obtained with the Fowler flap. During the past yearattempts have been made to obtain still higher liftcoeflicienta. First, a slot was added to the leadingedge of the Fowler-ty-pe wing, but only a slight increasein lift cmdlicient resultad. A special slot having a slatof good airfoil section was then developed and this inits best location gave a maximum lift coefficient withthe Fowler+-pe flap of 3.62 (Technical Note No. 459).Then still another slot was added, a tied slot nearthe trailing edge of the basic wing, which gave a slightadditional increase to 3.76, a total increase of about200 percent above the value for the wing with alldevices retracted. The investigation of the plainFowler-type flap is being continued in the 7-by 10-footwind tunnel to find the relative characteristic withFowler flaps of various sizes and to determine theloadings on the flaps.

Wind-tunnel tests have’ also been made with a flapconsisting of an auxiliary airfoil pivoted at the rear ofthe main wing as proposed by Wragg. The auxiharyairfoil k located so that a slot is formed between thetwo wings in a manner somewhat similar to that ofthe Fowler-type flap, but the auxiliary is not retractedinto the main wing. This arrangement with a 15 per-cent auxiliary airfoil gave a maximum lift about thesame as that obtained with a simple split flap.

Fiwd auxiliary a+o&—Last year a fixed auxiliaryairfoil had been developed which gave an increasedlift coefficient and an increased speed range, and whichwas thought advantagxms particularly because it hadno moving parts (Technical Report No. 428). Flightteats were made with the auxiliary airfoil mounted on

a small parasol monoplane (Technical Note No. 440).At that time the investigation had included only onesize of auxiliary airfoil and only one auxiliary airfoilsection. The results seemed sutliciently promising tomake it worth while to test auxiliary airfoils of othersizes and airfoil sections, and several sizes with threediilerent sections have now been tested in a sufficientnumber of positions with respect to the main wing todetermine the best arrangement (Technical ReportNo. 472). None of these has been found to be de-finitely superior in all respects to the original, althougha decidedly lower minimum drag waa obtained witha symmetrical section. The highest values of themaximum lift coefficients and the speed range criterion,CL,JCD-,=, were obtained with auxiliary airfoils withchords 11 to 15 percent of the main wing chord,although those as small m 7.5 percent of the mainwing chord gave nearly the same values aa the largersizes.

Tai.ffe$8 ai.rpfmaes.-Wind-tunnel tads were made of “a model wing having an aspect ratio of 3 and a taperedplan form with a straight trailing edge (TechnicalNote No. 463). The Clark Y airfoil section was usedthroughout the entiie span, with no washout. Aconstam%hord trailing-edge flap was used for longi-tudinal balance and control moments. The simplewing with no washout or change of basic section alongthe span had aerodymunic characteristics well suitedfor use on tailless airplanes. A higher lift coefficientwas obtained with the full-span flap deflected aa aunit to give longitudinal balance than with either theinner or outer portions of the flap deflected separately.Further tests are being made with the same baaicmodel having a fixed auxiliary airfoil mounted aheadof the leading edge for the purpose of increasing themaximum lift coefficient and improving the balancecharacteristic.

Commommrmm.-The Committae’s work on lat-eral control has been continued during the past yearalong two main line9. First, the search has been con-tinued for a lateral-control device that is completelysatisfactory throughout the entire speed range, includ-ing angles of attack above the std. More recentlythe work has been concentrated on lateral-control de-vices suitable for wings equipped with flaps or otherhigh-lift devices along their entire spans. During thepast year some of the control devices that the wind-tunnel investigation showed to be promising have beentried on an airplane in flight, with the result that con-siderable information has been obtained about thecharacteristics to be desired in a good lateral-controldevice, but it was found that each of the single lateral-control devices when tested in flight had at lead oneundesirable feature. One interesting point broughtout by the flight and wind-tunnel tests was that theyawing effect of the ailerons as observed by the pilotscorresponded tQ the yawing momenti as measured

REPORT NATIONAL ADVISORY

about wind axw, and not about body axes as hadpreviously been thought. The flight teata also broughtout the fact that the yaw@ moments caused by theailerons are relatively unimportant in crnisiig and inhigh-speed flight, but are of critical importance at theanglea of attack near rmd above the stall.

Conventional ailerons.-The invmtigation in the 7- by10-foot wind tunnel has been extended to include con-ventional ailerons of various shapes and sizes, with dif-ferential movements and with balance arrangements,on wings of various plan forms (Technical Reports Nos.419,422, 423, and 444, and Technical Notes Nos. 445,449, and 451). In all the teats the ailerons of wide-chord and short-span dimensions gave reasonably &@hvalues of rolling moment at the high angles of attackdefinitely above the stall, whereas the narrower aile-rons gave substantially lower values above the stall.It therefore seemed that the short wide ailerons mightgive at least fair control at angles of attack above thestall. The wind-tunnel tests showed, however, thatwhile some conventional aileron arrangements hadpositive ymving moments with respect to the bodyaxes, all gave adverse yawing momenti with respectto the wind axes at high angles of attack, regardlessof the ditlerential motion, or of such balancing arrange-ments as the Frise type. When tested in flight noneof the conventional ailerons, whether of long narrowor of short wide form, regardless of the differentialmotion used, gave control above the stall. Fromthese results it seems that with conventional aileronsthe secondary features, the adverse yawing moments,and the aggravation of the stall by the down-goingaileron over its portion of the wing, become moreimportant at ~ch an@s of attack than the directrolling moment given by the ailerons.

Wind-tunnel tests have been made with conventionalailerons on a slotted wing (Technical Note No. 443),and flight tests have been made on the lateral-controlcharacteristics of a low-wing monoplane equipped withboth slots and flaps, the flaps being coniined to theinner portion of the span to allow room for conven-

tional slotted ailerons (Technical Note No. 478). Theresults of these tests showed that the rolling-momentcoefficients obtained were about the same regardlessof whether the slots were open or closed, or whetherthe flaps were up or down, all of which is in accordancewith the results of the wind-tunnel tests. In fact, therolling moments measured in flight agreed very wellwith the rolling moments measured on similar aileronsunder static conditions in the wind tunnel when therolling action of the airplane wa9 taken into account inthe computations.

If conventional ailerons are used on wings withflaps, whether of the plain or split variety, a part ofthe span of the flap must in most cams be sacrificed.One arrangement ha$ been devised in which ordimwyailerons are used with a full-span split flap by retract-

COMMFIT’EE FOR AERONAUTICS 5

ing the flap into the wing ahead of the ailerons. Withthis arrangement, in order to bring the flap into +emost favorable position when deflected it is moved tothe rear as well as downward. Wind-tunnel tests haveshown that reasonably satisfactory rolling and yawingmoments are obtained by the conventional aileronswith $he flap deflected. With the flap retracted theconventional ailerons operate in the normal manner.A special iving havirg this arrangement is now beingfitted to a parasol monoplane for fliiht tests.

lMern.al ai.lermw.-A wind-tunnel investigation hasbeen completed on external ailerons composed ofseparate airfoils attached to but apart horn the mainwing. The external ailerons were tried in positionsall around the main wing, but particularly in fourregions: (1) In front of and below the leading edge;(2) above the nose portion; (3) above the trailing edge;and (4) below the trailing edge of the main wing.The ailerons in front of and’ below the leading edgewere found to give reversal of control at low anglesof attack. In the region above the forward portionof the wing the ailerons had rolling and yawing momentchtirqcteristics somewhat similar to those of spoilers,the rolling-moment coefficients increasing in magni-tude as the angle of attack was increased to andthrough the stall. For the ailerons above the trailingedge the characteristics were similar to those of con-ventional ailerons except for the yawing moments,which were better. When mounted behind and belowthe trailing edge, the external ailerons could be usedas lift flaps if deflected downward together. If de-flected diilerentially they acted like ordinary aileronswith unusually large adverse yawing moments.

The most favorable location for control at higha@es of attack up to well above the stall appearedto be just above the nose portion of the main airfoil,a short distance back from the leading edge. Flight .tests have been made on external ailerons in this posi-tion with two different types of deflection, in both ofwhich the ailerons were moved one at a time. Withone type of deflection the trailing edge was moved uponly, and with the other type the trailing edge wasmoved down only, these opposib deflections beingselectid because the wind-tunnel tests showed thatmoving the aileron in either direction from a criticalneutral position reduced the lift on the adjacent por-tion of the wing.

When tested in flight these ailerons had a lag, ordelayed action, when given the deflection in whichthe trailing edge was moved downward, but they werefree from lag when the tmiling edge was given theindividual upward deflection. In the ordinary flyingrange the acceleration in roll was found to be onlyabout half as great as that obtained with ordinaryailerons of approximately the same size, but the fialrate of roll was greater than that obtained with ordi-nary ailerons. The latter condition was not consid-

6 REPORT NATIONAL ADVISORY COUT’I’EE FOE AERONAUTICS

ered advantageous by the pilots. The ailerons gavempderate control at the angles of attack above thestall. As lms been found with all external aileronstested in flight, however, the control force was highat the high speeds, even with the aileron hinge axismoved as far back as possible without resulting inoverbalance at low speed. The work dealing. withexternal ailerons is still in progress and the reportsof the tests are not yet completed.

Floating tip ai.krons.-A wind-tunnel investigationhas been completed of floating tip ailerons havingvarious airfoil sections, hinge axis locations, and end-plate arrangements, on rectangular wings; on str~htwings with single and multiple floating tip ailerons ofnarrow chord; and on tapered wings with 2° of taper(Technical Report No. 424 and Technical Note No.458). In general, the floating tip ailerons gavereasonably satisfactory values of rolling moment atall angles of attack, practically zero values of ymvingmoment about wind axes, and a reduction in the un-stable autorotational moments, but they also gavepoor airplane performance characteristics, especiallyin regard to climb. The most promisii of the floatingtip ailerons seem to be those on wings of extreme taper.In this case, very light control forces are required andit would seem that there should be no great reductionin @rplane performance if the span of the fixed partof the wing is suiiicient for the rate of climb desired.

Upper-sur&ca ailerons.-These ailerons are usedwith split flaps and are formed by deflecting the uppertrailing-edge portions of the wing above the splitflaps. They are deflected upward individually. Bothwind-tunnel and flight tests showed that, while mod-erate rolling control can be obtained at angles of attackbelow the stall with the flap either deflected or re-tracted, if simple unbalanced upper-surface aileronsare used the control forces required are excessivelyhigh even though the ailerons have a narrow chord.Reports on both the wind-tunnel and ilight tests arein preparation. Work is now being carried on in the7- by 10-foot tunnel to investigate the possibili~ ofobtaining a suitable reduction of hinge moment bymeans of proper hinge location and aileron proiile.

Spo&e.—VrLrious spoiler arrangements have beentested both in the wind tunnel (Technicsd Note No.415 and Tactical Report No. 439) and in flight(report in preparation). These spoilem consistedessentially of plates and surfaces arranged to projectfkom the upper surface of a portion of the wing inorder to reduce the lift over that portion. Thespoilers located near the nose of the wing gave con-trol at rmgles of attack above the stall, but, unfor-tunately, below the stall they had a definite lag ordelayed action due to an initial but imperceptibletendency to roll in the wrong direction. The timehm the deflection of the. control to the start of theroll in the desired direction averaged about one half

second. The lag was found in tlight with each of thothree forms of spoiler tested, the first being a flap setin the upper surface and hinged at the front edge, thesecond a retractable spoilar projecting out through aslot in the upper surfaca of the wing, and the thirdthe retractable spoiler cut to saw-tooth form. Theseresults seem to eliminate the simple spoiler locnted inthe forward portion of the w-@ as a satisfactory lat-eral-control device when used by itself, but, if controlabove the stall is of sui%cient importance, a satis-factory arrangement free from lag cm apparently beobtained by the proper combination of spoilers andordinary ailerons. The spoilem can be arranged toreduce the aileron hinge moments if desired, eitherby means of their location or their connecting linkage.

In regard to control at angles of attack above thostall, the flight tests have shown that the lateralinstability above the stall may be so violent as toeliminate the possibili@- of handling the airplane sds-factorily even with an effective lateral control. Con-sidering this condition it seems that even for occasionalemergency use control above the stall may be ofslight value unless it is accomptied by stability.

If the spoilers are moved sufficiently far back rdongthe chord of the wing there is no doubt that the lagcan be eliminated. Unfortunately, M the spoiler ismoved back its effectiveness in giving control at mglcsof attack above the stall is lost. The present plansare ta continue flight tests to find the most forwardspoiler location free from lag. Tests are now underway with the retractable-type spoilers near the trnil-ing edge of the wing. In this position they mightwell be called “retractable ailerons”, for they giveapproximately the same rolling and yawing momentsas the upper-surface ailerons but with the advnntngeof very low control forces, for with this device thehinge moments can be made practically zero.

Aerodynamic balancing of control w@m.s.-Consid-erable interest has been centered during the pnst yearon means of balancing the forces required to operatethe various control surfaces of an aiiplane. An in-vestigation hns been made in the 7- by 10-foot tunnelon a model wing with ailerons and balanced surfaceaof various kinds. Hinge moments and rolling andyawing mom6nt.s, as well m the generrd perfornmnccwith the various arrangements, were measured. Onetype of balancing arrangement investigated consistedof flat plates or tabs attached to the trd.ing edge ofthe ailerons and deflected various amounts. Anothertype of tib was formed by deflecting the trailing-edgeportion of the aileron iteelf. The latter type provedmore effective and complete servo-control could beobtained for moderate aileron deflections when theinset tab was 20 percent of the aileron chord and cov-ered the entire aileron span. The hinge moments forlarge aileron deflections, however, were greater withthe tabs than without. Further -work is in progress

REPORT NATIONAL ADVISORY

with inset tabs and horn-and~paddle-type balances onailerons, and with inset tabs on ruddem and elevatorsalso.

STAB~I~.—A theoretical study of stability, based onthe theory of small oscillations, is being made with aview to making possible the rational prediction of thestabili~ characteristics of an airplane by simple means.

~ect oj wing-tip 8hape.-A wind-tunnel inves.tig~tion of the effect of wing-tip shape on lateral stabili@-is in progress. Teats have been made with tips hav-ing rectangular and curved plan forms, and with thetip in front curved upward and downward differentamounts. The tests include 6-component force andmoment measurements at several angles of yaw, aswell as rotation testi at zero ymv. The results showthe effect of tip shape on general perforwuw and onfour of the lateral-stability factors+amping in roll,and variation of the rolling moment, yawing moment,and cross-wind force with sideslip. It was found thatthe rectangular tips gave higher values of the rollingand yawing moments due to sideslip than the curvedtips, while the damping in roll was about the same forall of the tips tested.

~ective dihedraL-A detded wind-tunnel investiga-tion is being made to determine the effects of dihedralon lateral stabiliw and on generil performance. Inthe 7- by 10-foot wind tunnel tests are being madewith wing models having various amounts of the spandeflected upward to give dihedrd. The results ob-tained to date indicate that a dihedral angle only inthe outer 25 percent of the wing is quite effective inproducing rolling moments due to sideslip up throughlarge angles of attack. In addition to the wind-tunnelinvestigation qualitative flight tests are being madein which the lateial stability is being found for aparasol monoplane with &he&-al angles ranging from0° to 9°.

LANmrw+.-The cinematographic apparatus de-veloped for studying the motion of airplanw in flightclose to the ground, particularly in landings, has beenutilized in an investigation of glide landings in gustyair. The airplane used in this investigation wasequipped with unusually long shock-absorber struts.In the teats with the elevator held stationary, for theworst case recorded the attitude of the airplane vaxiedfrom 14° nose up to 9° nose down, and the rate ofdescent varied from 28 feet per second to 4 feet persecond, while the airplane was descending from 55ofeet to 36o feet. At the present time a paper is beingprepared in which the results of this investigationwill be presented, together with the results of an in-vestigation of the tiariation in wind speeds close tothe ground.

The above-mentioned apparatus has also been usedin investigations of the relative efficiency of two type9of long-stroke shock-~bsorber struts, and of the land-ing characteristics of an autogiro. The latter investi-

COMMHTE13 FOR AERONAUTICS 7

gation was undertaken at the request of the Aero-nautics Branch, Department of Commerce, to providedata for use in the formulation of design rules..

TAKE-• FF.-Acomparatively simple method of cal-culating the length of take-off run has been developedfrom the assumption of a linear variation in net accel-erating force with air speed. This method has beenpublished during the year in Technical Report No. 45o. .

A flight investigation was made to determine theeffect of automatic slots and plain flaps on take-off,the tests being made with a small low-wing mono-plane. The take-off run was materially reduced withslots but not with flaps, the magnitude of the effectsbeing dependent to some extent on the gross weight.The dMerence in the eflects of the two devices layprincipally in the fact that the flaps increased the dragthroughout the take-off run and thereby retarded theacceleration, whereas the slots had no appreciabledeleterious effect d&ing the preceding ground run.

Further information on the effect of flaps on take-offrun is available from tests in the full-scale tunnel ona small parasol monoplrme. Calculations based onthe power characteristics with a 95-homepower engineand a tied-pitch propeller indicated that a slightreduction in the calculated take-off run wotid beobtained with a flap depression of about 27°, butbecause of the poor climb with the flaps down, the totaltake-off distance required to clear an obstacle 100 feethigh would be greatly increased for flap settings greaterthan 20° and would not be appreciably improved bylower settings.

In an attempt to calculate the take-off run fromknown airplane and propeller characteristics it wasfound that no one value for the coefficient of groundfkiction would give satisfactory agreement with theexperimental data for all take-off conditions. Astudy is being made of the tiuence of various factorson take-off.

The recent perfection of several types of controllablepropellers has increased the interest in methods ofcomputing the possible performance .of such propellers.A report has been prepared pointing out some of themetho da to be used in such calculations making useof data previously published by the Committee. Thereport (Technical Note No. 484) also shows the possi-bility of bcreasiug the performance of some airplanes.

In the computation of the propeller performanceof airplanes, particularly of seaplanes, it has been foundthat the information previously published in TechnicalReport ISO. 350 was not complete enough in the low-speed range for the calculation of the mailable thrustof the propeller. The origimd data have been recom-puted, a new coefficient being used, and the resultsare being presented in a new report in the form ofcharts which will be useful to designers in computingthe low-speed characteristics of propellers.

8 REPORT NATIONA3 ADVISORY

When retractable lsndmg gears are used on a low-wing monoplane the question arise6 how the liftcoefficient of the wing is affected by the open wheelwells in the lower surface of the wing when thelanding gear is extended and how the time for takingoff may be affected. In order to furnish informationon this point, the Committae was requested by theArmy Air Corps to make teds in the full-scale tunnelon a Lockheed Altair airplane. It was found that thewheel op&@s in the lower side of the wing havea negligible effect upon the lift and take-off of theairplane. The results are given in Technical NoteNo. 45o.

M.ANEuvnrt.MIrLrrY.-A report on the m&neuvera-bility of an observation airplane, an investigationundertaken at the request of the Bureau of Aeronautics,Navy Departmentj has been published (TechnicalReport No. 457). Consideration has been given to thedevelopment of a criterion for maneuverability basedon the results of previous teds.

Smrrmw.-lhtensive research on the problem ofthe spin has been continued both in flight and in thevertical tunnel, the latter having been in regularoperation throughout the past year (Technical ReportNo. 456). Attention has been concentrated largelyon the factors affecting the steady spin and recoveryfrom it, for the ultimate purpose of imuring in thedesign of airplanes that proper recovery will be ob-tained, or that the steady spin -will be entirelyprevented.

A paper has been published on the effect of sharpleading edges on the spin (Technical Note No. 447).There has also been published a paper (TechnicalNote No. 468) on the resuh% of a study of the influenceof the various factors affecting the steady spin. Inthis study the predicted influence of various modifica-tions in airplane design features were correlated withthe results of flight tests as reported from numeroussources. An analysis of the results obtained in aflight investigation conducted on a small biplane, ofthe effect of control setting and mass distribution onthe steady spin, has been ccmpletid and a paper onthis subject is now being prepared. It was found thatin general the observed effect of extensive changes inmass distribution could be predicted by utilizing theknowledge already available from previous theoreticaland experimental studies of the problem. “

There are rather conclusive indications that provisionof sticient damping yawing momenta offem the mosteffective method of eliminating bad spinning charac-teristics, and several researched designed to provideadditional information on the amount of yawing mo-ment desired and the method of securing it effectivelyhave been tied out or are now in progress. Aninvestigation conducted in the vertical tunnel to deter-mine the efFect on spinning characteristics of locatingthe stabilizer and elevator in several fore-and-aft

COMMTIT1313 FOR AERONAUTICS

positions and also in twg vertical positions has beencompletid and a paper on the results haa been published(Technical Note No. 474). The results indicate thata very favorable increase in yawing moment is obtainedby a high and/or a rearward position of the hofiontaltail surfaces.

In the same connection the spinning characteristicsof a biplane of the fighter type have been investigatedin ilight with various modi.fhtions to improve theeffective fln area. In its orig$nal condition this &plane wouId occasionally fail to recover when thecontrols were manipulated ti accordance with thenormal procedure for recovery. The character of thespin was ii-at improved to an extent that made it safefor spinping by the addition of considerable fin meaabove the fuselage, a modification that could be readilyincorporated in the existing airplanes of that type.The investigation was then continued to detemnine theeffect of raising the stabilizer, n modification thatwas expected to prove very beneficial, on the basis ofprevious studies in the vertical tunnel. In teds nowcompleted a very marked improvement in the charac-tb of the spin has been brought about by raising thestabilizer to the top of the vertical iin. At the presenttime the effect of an intermediate stabilizer positionis being investigated, such a position being morereadily adaptable to structural design requirementsthan the extreme upper position.

The flight investigation with this airplane has beenvery closely correlated with tests in the verticaltunnel on a model of the same airplane primarily forthe purpose of detenninin g the extent to which agree-ment might be expected between model and flight3pinning tests, and possibly of deriving factora forconverting model apinniqg rcmdts to full scale. Themodel data have not yet been completely analyzed.

A third research concerned with the yawing momentscontributed by various parts of the airplane in spinsis now being carried out in flight on a small biplanepreviously used for muss-distribution studies. Thelateral forces on the fin, rudder, and fuselage are beingdetermined by pressure-distribution measurements,md at the same time the spinning motion is deter-mined so that resultant moments can be computed.The yawing moment developed by the remainderof the airplane, chiefly the wings, is then found.

At the request of the Army Air Corps, three modelsof special pursuit airplanea were tested in the verticaltunnel for prediction of their spinning characteristics.[t is interesting to note that the characteristics asmeasured compared favorably with what had been pre-dicted on the basis of previous teds with other modelsm the spinning balance.

An experimental method for detemninin g themoments of inertia of airplanes for use chiefly in3pinning studies has been used by the Committee forseveral years. Essentially, the method consists in

REPORT NATIONAL ADVISOEY

.,

COMMITTW3 FOR AERONAUTICS 9

suspending the airplane so that it can oscillate as apendulum. Reiinementa in the method have beenmade from time to time, some of them being of funda-mental importance. A report has been published(Technical Report No. 467) describing the procedurefollowed in these experiments, particularly the methodemployed in correcting for effects of the ambient air.

AERODYNMC INTERFBB~CE AND Dra~.-Thebroad basic investigation of aerodynamic interferenceand drag previously undertaken has been continuedthrough the year. The invedigation is intended todetermine where and under what conditions inter-ference effects may be of importance, and how adverseinterferences between airplane parts may be reducedund favorable interferences utilized. The -work isndvrmtageously divided among various sections of thelaboratory.

Wing+uw-fuge ir&&mnCe.-h extensive inv3s@a-tion dealing largely with interference tiects betweenthe fuselage and the wing has been in progress duringthe year in the variabledeti@ wind tunnel. Thetests are made at a high value of the Reynolds Num-ber, and deal with combinations of variously shapedfuselaga and wings in different relative positions. Alarge part of the test program has been carried out andthe results are being analyzed, but the investigationhas not progressed su5ciently far to mrrant thedrawing of conclusion+

The best means of determiningg interference effectsis by measurements on actual airplanes in the fuU-scale wind tunnel where the tests can be made withrmd without the slipstream, and where flow surveyscan b~ made behind the airphme. TWO investigationsof this nature have been undertaken during the year.Wmg-fuseloge interference and buffeting w-ere in-vcstigmted on a low-wing monoplane displayingexcessive drag and tail buffeting at high angles ofattack, succcs-sive modifications being made, includingthe addition of variously formed iillets at the junctureof the wing and fuselage, the installation of a NationalAdvisory Committee for Aeronautics engine coding,the use of shortipan auxiliary airfoils, and provisionfor reflexing the trailing edge of the wing. Prelimimqresults of this investigation have been published inTechnical Note No. 460.

A more complete report is in preparation in whichwill be shown surveys of the flow about the tail sur-faces with and without power and with the variousmodifications mentioned. A special survey apparatusdescribed previously was used for this work. It wasfound that the fillets, either alone or in combinationwith the National Advisory Committee for Aero-nautics coding, reduced the buffeting and inter-ference to unobjectionable magnitudes at anglea ofattack up to the stall. The best results mre obtainedby the use of fillets together with the National AdvisoryCommittee for Aeronautics coding.

4070S-3-2

bother full-scale investigation of wing-fuselageinterference on a YO-31A airplane is in progress in thefull-scale tunnel. A mock-up of this airplane, whichwas originally built with a gull wing, has been arrangedfor the installation of wings in three positions represent-ing a high-wing, a mid-wing, and a Iow-wingmonoplaneand in the latter position a full cantilever wing will betested as well aa the braced wing used in the otherpositions. Both force teats and preasurc distributionmeasurements will be made for the whole series of tests -and these, taken with air-flow measurements at thetail and engine power data, will give a complete pictureof the effecp of wing-fuselage interference on thisparticular ailplane. The part of the investigationdealing with the gull wing has now been completedand the results are being analyzed while the nextwing arrangement is being set up.

Wing-nacelle propdler remurch.-The extensive pro-gram of research on the mutual influences of wing,nacelle, and propeller has been continued in thepropeller-research tunnel. Investigation of nacelleswith tandem propellers, of nacellca with pusherpropellers, and of nacelles with tractor propellers onbiplane wings has been completed. A large number ofsupplementary trots correlating thwe investigationswith the investigations of tractor propellers on nacellesand monoplane wings have also been made. Reportscovering these various part9 of the invedigation arenow in preparation.

The effect of the shape and size of the wing on themutual interference has been investigated by means oftests on a vving of Clark Y section and smaller chordfor comparison with the earlier tests with a thickwing of large chord. Results of this investigationhave been published as Technical Report No. 462.The general conclusion draw-n from the investigationis that a completely cowled tractor nacelle locatedahead of the leading edge of the wing is the bestarrangement. The tandem-nacelle arrangement suf-fered largely from the l@h drag of the engine nacelle.The same is true of the pusher nacelle arrangement; in “fact, the pusher part of the nacelle or nacelle adjacentto the pusher propeller appeam to be the undesirablefeature in both the pusher and tandem arrargernents.None of these arrangements apprcachm the efficiencyof the best tractor-nacelle arraq+ment. There appearto be good grounds for supposing that an arrangementconsisting of an engine located ahead of the leadingedge of the wing in a National Advisory Committee forAeronautics cowled nacelle and an extension shaftcarried to the trailing edge of the wing with thepropeller located at the end will have high efficiency.Tests are soon to be made with this arrangement.

Most of the precedimg tests have been made withnacelles for air-cooled radial engines. The liqnid-cooled airplane engine has not been overlooked; sometests have been made to determine the propulsive

10 REPORT NATIONAL ADVISORY COMMITTDE FOR AERONAUTICS

efficiency and the interference effects of a Iiquid-caoledengine nacelle and a wing. The tests made thus fmindicate that the largest drag-producing componeniof the nacelle of the ordimmy type is the radiator,which is normally exposed below the nacelle. A %s1was also made with a radiator completely surround@the engine and enclosed within a nacelle of circuhucross section, giving an outward shape similar to thafof an air-cooled engine nacelle. The results of thiEtest indicated that the drag of the usual liquid+ooledinstallation could be ixmsiderably reduced by such anarrangement,

The great mass of data obtained on wing-nacelle-propeller effects in the propeller-research tunnel wasobtained on wings of 15-foot span, aspect ratio 3,with a propeller of 4-foot diameter. If the propeller-nacelle interference extends more than about twodiameters outboard of the thrust axis, then the effect isincompletely measured on such a smabpan wing.In order to check this possibility, the same nacelle-propeller combination has been tested in the full-scalewind tunnel in three positions relative to a wing of thesame chord and section whose span was progressivelydecreased from 30 to 25, to 20, and finally to 15 feet.Forces, propeller charactmistics, and pressure dis-tribution were measured and a preliminary comparisonshows the effect of span to be not so large as to invali-date the test results on short spans. The results ofthese tasts in the full-scale tunnel are being preparedfor publication.

Drag of kmding gea.rs.-It has been r&d for.

some time that the drag of the landing gear con-stitutes in many cases a large part of the totfd dragof the airplane. That manufactumm of airplanes arecognizant of this fact is witnessed by the numerousinstallations of retractable landing gears in recentairplanes. The additional weight and the mechmicalcomplexity have retarded the general adoption ofretractable landhg gears. That these difficulties arebeing surmounted is attested by the numerous installa-tions of retractable gears in recent designs, but the useof nonretractable gears in several high-performanceairplanes indicates the need for more information onthe possibilities of reducing the drag and the unfavor-able interfamnce effects.

An investigation of the drag of lantig geara hasrecentiy been completed in the propeller-researchtunnel. In this investigation a full-size airplane fuse-lage was mounted on the balance and a large numberof landing gears were attached to this fuselage and thedrag determined. The drag of the complete landinggear as thus determined was supplemented by tedson component parts which were made in the 7- by 10-foot wind tunnel (Technical Report No. 4’08). About20 types of landing gears ware investigated which,with numerous varirkions, brought the total numberof tests b over 100. A number of styles of wheels

and wheel fakings and fairings between wheels andstruts were tried, so that the whole research consti-tuted a fairly complete study of landing-gear effects.The final report including analysis and design studies “has been completed.

It was found that landing gears of the older typeswithout any particular streamlining and having veryhigh drag can be greatly improved by fitalling filletsbetween the struts and wheels and fairings over thewheels. Of the newer types, the cantilever-type gearhad a fairly low drag but the lowest drag was obtainedwith a gear protruding vertically below the wing andcompletely faired in. With this type the drag wasreduced to about 13 pounds for the landing gear at100 males an hour. It WSS d10 found that, as far as@O is concerned, the various types of wheels, suohas high-pressure, low-pressure, and streamlined wheels,have relatively small effect on the total drag, but thatinterference effects between wheels and adjacent mem-bers is much more important. Taken all together, itappears that the drag for the exposed landing gear canbe reduced to a point where its effect even on the high-performance airplane will be relatively small and theconsequent complication of retractable gears can beavoided in a number of instances.

Cowling.-The very gen~a.1 adoption of the Na-tional Advisory Committee for Aeronautics cowlingand its importance for high-speed flight have pointedto the desirability of further research ta establish moretrustworthy design data. An extensive systematicinvestigation has accordingly been undertaken, con-sisting of three parts: (1) the cooling requirements ofan air-cooled engine, to be mtablished by the powerplants division; (2) the best cowling arrangement toobti the necessary cooling with minimum drag, tobe established by model tests in the 7- by lo-foottunnel; (3) verification of the results from parts (1)and (2) by cowling tests on full-size engines in thepropeller-research tunnel.

Part (1) is in progress by the engine research division’,Part (2) is in prcgresa in the 7- by lo-foot tunnel, andincludes the effect of changes in the front opining, therear opening, the size of the nacelle, the camber of theleading part of the cowling, and the effect of differenttypes of leading edge. The investigation has not beencarried far enough to warrant definite conclusions.

Prop&w drag.-l?or those airplanw whoge func-tions require that they be dived at terminal velocity,the accurate prediction of this velocity is of import-ance. Stice the propeller may offer considerableirag in fast dives and since it exerts rL controllingnfluence on the engine speed, the Committee was:equested by the Bureau of Aeronautics, NavyDepartment, to make an investigation to determinehe quantitative nature of these effects to the end thatmecise estimates of the terminal velocity could benade. This investigation included flight dive tats

,

REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 11

nnd wind-tunnel propeller tests. During the past yearthe information has been analyzed and a report pre-pared (Technical Report No. 477), which presents theresults in a form readily usable for the quantitativedetermination of the influence of the propeller on theterminal velocity and engine speed. Some of thepropdler tests were extended to include the negativethrust range of operation applicable to this conditionof flight, and the results have been given in TechnicalRepoit No. 464.

Use o~ thewnoke tunnel and the high-8peedtunnel.—The smoke tunnel and the high-speed tunnel have beenemployed in connection with interference studies.Investigations in the smoke tunnel, however, havebeen made primarily to study % utility for such re-Searche% For example, the air flow was examinedabout a model on which was simulated a windshieldof the forward-eloping V-type as used on some trms-port airplane9. Observations of the smoke flow in-dicated a Imge wake. The windshield was then altereduntil a form was reached which gave a more satis-factory flow. The actual drags of the original andfinal windshields were then compared by tats at alarge value of Reynolds Number in the variable-density tunnel. The results confirmed the deductionsfrom the observations in the smokeflow tunnel inthat they showed the original windshield to have anexcessive drag and the final form less than half that ofthe original.

Another invedigation of particular interest wasstarted in the smoke tunel and continued in the high-Bpeed tunnel. In the smoke tunnel the flow about astreamline wire (lenticukr section) model was ob-served to indicate a relatively high drag. The flow wasfound to be improved by the addition of small roundwires on the surface of the streamline wire to forma longitudinal protuberance on either side of thesection contour somewhat behind the leading edge.Various sizes and positions of the protuberance wereinvestigated. Later the investigation was continuedin the high-speed tunnel where full-scale wires could betested at full speed, and the drag accurately measured.A streamline m“re of nomkd size, 0.5 inch with roundwires of 0.003-inch diameter soldered a.lorqg its sur-faces ta form the protuberance, at certain speedsshowod a drag reduction due to the protuberances ofmore than 40 percent.

E~ecf8 oj wrface roughnms.-(llm question some-times arkes as to the effect of surface roughness onthe aerodynamic characteristics of a wing, and twoinvestigations of a minor nature have been conductedon this subject during the year. Teds were made inthe variabledensity wind tunnel on a number of air-foils of the National Adviso~ Committee for Aero-nautics 0012 section on which the character of thesurface was changed from a rough to a very smoothfinish. Measurable ndversc effects were found to be

caused by small irreg.darities in airfoil surfaces whichmight ordinarily be overlooked. These results were ,published in Technical Note No. 457.

An investigation of the effect of rivet heads on thecharacteristics of a 6- by 36-foot Clark Y metal airfoilwas carried out in the full-scale tunnel and the resultspublished in Technical Note No. 461. The effect ofconventional brazier-head rivets on the &g of thewing was found to be large, and an investigation ofvarious types of flush rivets is next to be undertaken.

Awoms.-l%eow of m-rig wctiOm.-A report on theaerodynm”c potential theory of wing sections (Tech-nical Report ATO.452) has been prepared in which ispresented a unitied rigorous treatment of the generaltheory of monoplane wing sections of any, shape.The numemus special cases that have been previouslytreated in the aerodynamic literature are reduced tospecial cases of the general theory, which permits aclearer perspective of the entire field of wing theory.A comparison of the predicted theoretical pressureawith experimental work for the National AdviscnyCommittee for Aeronautics M6 airfoil at 12 diffmentangles of attack presents a striking illustration of thevalue of the theory. In a later report (TechnicalReport No. 465) application of the general theory ismade to 20 conventional or selected airfoils. Thetheoretical distribution of pressure at lift coefficientsof O, 0.5, 1.0, and 1.5 is presented graphically. Analysisand discussion of the results show clearly that many ofthe aerodynamic properties and characteristics ofairfoils are explainable and predictable on the basis ofthe theor@ical pressure-distribution curves.

Inwtigafion of ai~oil shape.-The systematic in-vestigation of airfoil characteristics as affected byvariations of the airfoil shape has been continued inthe variabledensity tunnel and a report (TechnicalReport No. 460) has been prepared covering the testsunder comparable conditions of 78 related airfoils.

The tests were made primarily to investigate air-foil characteristics as affected by variations of thesection thickness and the mean-line form. One of theobjects of investigating a wide variety of related air-foils, aside from supply@ data to facilitate the choiceof the most satisfactory airfoil for n,given application,was to determine the trends with changw of shape thatmight be followed in order to design new shapes havingbetter characteristics. The most promising possibilityof improvement was found to be with those airfoilswhich have the position of the maximum camber wellforward. A number of sections of this type havetherefore been developed from the original family withthe expectation of finding new sections that give areasonably high maximum lift without an excessivelylarge pitching-moment coefficient.

Among the 78 related airfoils considered in the pub-lished report are some having thiclniem forms ditler-ing from the basic one, notably those having leading

12 REPORT NATIONW AD~ORY

edges blunter and sharper than the basic leading edge.The consideration that the tioil profile must enclosean efficient structure, however, dictates the investi-gation of other thiclmess forms. With single-sparconstruction, for example, an airfoil section ha~m themaximum thickness well forward may be desirable.On the other hand, for wings like the Fowler variable-area wing a deep rear spar may be required. A thick-ness form having the maximum thickness fartherback than 0.3c may then be desirable. Furthermore,various thickueas forms have never been studied underconditions corresponding to full-scale airplane wings.Some thickness forms, such as one having the maxi-mum thickness at 0.4c, which appears from tests inthe high-speed tunnel to be better than the basic oneat very high speeds, may in flight be more eilicientaerodynamically.

ScuZe e$ect.-The results of airfoil tests in thevariable-density tunnel and in the full-scale tunnel” aswell as indications from flight tests show that a ratherlarge variation of airfoil characteristics with theReynolds Number is to be found within the range ofvalues of the Reynolds Number encountered in flight.Data horn tests of an airfoil at only one value of theReynolds Number cannot therefore be consideredadequate, but must be supplemented by some lmowl-edge of the changes produced by varying the value ofthe Reynolds Number from that of the test.

The Reynolds Numbers common to modern flightlie in the range between 2,000,000 and 20,000,000.Airfoil results from wind-tunnel tests have beenavailable only up to aReynoldshTumberof about 3,000,-000, obviously indicating that an extension of airfoilcharacteristics further into the flight range is highlyimportant. The characteristics of the Clark Y airfoilwere therefore measured in the full-scale tunnel over arange of Reynolds Number from 350,000 to 5,600,000at maximum lift, and from about 350,000 to 9,000,000at minimum drag. This wide range was obtained bytesting four similar metal airfoils with spans of 12,24, 36, and 48 feet at velocities from 30 to 118 milespSr hour.

The maximum lift coefficient for the Clark Y airfoilAows a steady rise in value -with increase in ReynoldsNumber while the minimum drag coefficient shows adecren.se in value with increase in scale. A report isin preparation indicating the variation of the airfoilchmacteristica with Reynolds Number, and makingavailable for design purpos= these large-scale data.

Tapered air@i.ik.-Other work on airfoils includmroutine tests or the tabulation and analysis of datarequested by the military services, or by the Depart-ment of Commerce. Some of these invea@gations havedealt with tapered airfoils rather than airfoil sections.Several tapered airfoils were tested in the -mriabh+density tunnel at the request of the Army Air Corps toprovide data for inclusion in the handbook of instruc-

COMMJTI?EE FOR AERONAUTICS

tions for airplane desi=mers. In connection with theinvestigation of tapered airfoils a technical note(no. 483) has been prepaxed presenting in short formfor convenient use by designers the theoreticalpitching-moment characteristics of tapered wingshaving various plan forms and having sweepback andtwist. TIM information is applicable to the design ofwings for ordinary airplane9 as well m tailkw airplanea.

CompremilriL@ e3eei%.-A technical report has beenpublished (no. 463) giving a deactiption of the high-speed tunnel and an account of the tests of o seriesof six commonly used propeller sections, showing theeffects of compressibility at air speeds up to 86 percentof the velocity of sound. The investigation of theeffects of compressibility has been further extendedduring this year to include a study of the importantvariations of airfoil shape. Eleven related symmetri-cal airfoils have been tested over rLwide speed range todetermine the effects of variations in the leading-edgeradius, the thiclmeas, and the location of the maximumordinate, as well as the effects of compressibility.The analysis of these results is now nearing completionand it is indicated that the best position for tlm maxi-mum ordinate is 40 percent of the chord aft of theleading edge. The effects of variations in the lend-ing edge radius on minimum profle drag for airfoils 9percent thick are negligible for values of the radiusless than 0.0089c.

The results of this investigation were used to de-termine a thiclmem distribution for use in the develop-ment of cambered airfoils. Three cambered airfoilswere twted; one of these, the National Advisory Com-mittee for Aeronautics 216 airfoil, is superior at highspeeds to both the Clark Y and R.A.I?. 6 propeller&foils having the same thiclmws. This airfoil is 9percent thick; its mrcximum ordinate is ~t 40 percentof the chord aft of the leading edge, and its lwling-edge radius is 0.0022c (approximately one quarter theusual value for the National Advisory Committee forAeronautics family airfoils). The mean camber linecorresponds to that of the National Adviso~ Com-mittee for Aeronautics 24 series.

A detailed investigation of the drag of fundamentalshapes-circular, elliptical, and prismatic cylinders—is now in progrem. The tests are being conductedover a speed range extending up to approximately65 percent of sound velocity. Drag tests of cylindersof various sizes show remarkably close agreement whenthe results for the lower speeds are plotted againstReynolds Number and the results for all the circularcylinders are in excellent agreement as to the speed(0.4 sound velocity) at which the compressibilityeffects become of tit importance.

Bown&r@.ayer cordroL-A number of investig~tions have been made in previous years, both by theCommittee and elsewhere, showing rather stmtlingeffects of the use of blowers to suck air in through slots

REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 13

in the surface of a wing or to blow it out. Most ofthese investigations havo been made on relativelysmall models, and trustworthy results have beendiilicult of attainment because of the smallness of themodels and because the amount of auxiliary apparatusrequired and the method used for attaching it to themodel necessitated numerous corrections. An invedi-gmtion is now in progress in the propelIer-researchtunnel in which a large model is used with the blower inthe wing itself. In addition to the measurements oflift and drag, apparatus has been installed for measur-ing the thick.iess of the boundary layer and thepressure distribution over the wing. The power inputto the motor is, of course, measured also. Although itis realized that the use of a blower for suction orpressure is not now attractive from a practical stmd-point, it is believed the results will provide a deiinitecontribution to our knowledge of the boundmy--layerclmxacteristics of the wing.

JET-BOUNDARY Investigation.-The unique possi-bility of obtaining results in the full-scale tunnel fordirect comparison with flight results made it im-portant to investigate all factors which might tend tocause a discrepancy between the wind-tunnel andflight results. That the limited boundary of a wind-tunnel jet causes a change in the aerodynamic charac-teristic of a body tested therein is well known, and atthe time this tunnel was put in operation there was notheoretical correction factor available for this type ofjet. An investigation was therefore undertaken todetermine experimentally the jehboundary correctionfactor. The results have verified in a very satisfactorymanner the theoretical factor for this jet which becameavailable during the progress of the work.

The procedure consisted in measuring the charac-teristic of geometrically similar airfoils graded in sizefrom large to small and then in extrapolating plots ofthem measured characteristics to simulate the condi-tion of a finite wing in space. A preliminary study ofthe kst data indicated an apparent contradiction ofthe general theory of jet boundary. After further in-vestigation this discrepancy was clarified when adistortion of the velocity field in front of the airfoil,caused principrdly by the wake from the body carriedaround through the return passage, was shown to beresponsible. A close agreement was shown to existbetween the characteristics of several airplanes asmeasured in flight and in the tunnel when the jet-boundary correction and the correction for wake effector blocking were applied. The results of this investi-gation are being prepared for publication as a technicalreport. The theory for an airfoil of finite span in anopen rectangular wind tunnel has been covered inTechnical Report No. 461.

STRUCTURALLoiunm.—The studies of the flightloads on airplane structur~ which have been made inthe past 3 years have resulted in a marked advrmca in

knowledge of this subject. These investigations havebeen continued, either to add to the existing statisticaldata on some phases of the subject or to pursue furtherthe underly@ prinpipl~ of phenomena not yet chmrlyunderstood.

LOUG?fuctors.-Four airplanes have been used in aninvestigation of the relation between control forces andacceleration in pulling out of fast dives. A theoretical’study of this relation has also been made to determinethe powibility of utilizing a stick-force formula in load-factor estinmtea. The results of these investigationsindicate (1) that the stick force has no appreciableinfluence on the probable applied load factor in thosecases where the forces are within the pilot’s strength,(2) that the pilot’s opinion of the control “heaviness”and maneuverability of the airplane may be greatlyinfluenced by a number of qualities of the airplane notdirectly related to the stick force, and (3) that stick-force fornmk are untrustworthy for Aimntingprobable applied load factors.

A statistical study of applied load. factors and ‘corresponding air speeds has been in progress on anumber of airplanes under actual operating conditions,for which a special type of instrument has beendeveloped. The instrument records acceleration andair speed, and has been named the “V-G recorder.”A number of these instruments have been in constantuse throughout the past year on various military andnaval aircraft, commercial transport airplanes, anda few privately owned airplanes. The data beingcollected cover the loadings experienced in normaloperation, ranging from the conditions correspondingto violent maneuvem to those resulting from atmos-pheric gusts. Although the data so far accumulated “are insdicient to jnd.fy iinal conclusions, a veryconsiderable advance has been made in knowledge ofthe loading conditions to which airplanes are subjected.Among several interesting points which have developedin regard to the loads resulting fkom gusty air, perhapsthe most impressive was a load factor of 5.2 applied bya gust on an airplane cruisii at 190 miles per hour.This value, while unusual, illustrates the possibilityof large gust loads in rare instance9. Assuming asharp-edge gust, the gust velocity for this case wascomputed to be 40 feet per second.

Load dtirilmtion.-several questions relating tothe problem of load distribution have been givenattention during the year. Since the preparation ofTechnical Report No. 445, which presents workingcharts for the determination of the lift distributionbetween biplane wings, further study of this subjecthas resulted in Technical Report No. 458. The influ-ence of the fuselage has been evaluated from pressnre-distribution tests made on two conventions-l biplanesin f@ht. This latter information may easily be usedin conjunction with the charts for the pure cellule.

14 REPORT N~TIONAL ADVISORY

Studies have also been made of the influence ofbiplane interference on the moment coe5cients of theindividual wings and on the span-load distribution.In regard to the moment coe5cients, it. has beenfound that the biplane effect is completely over-shadowed by other influences such as surface rough-ness, imperfect proiiles, rmd experimental error. Thespan-load distribution does not appear to be appre-ciably influenced by biplane interference.

Experimental pressure-distribution investigationshave been continued on an observation airplane rmda diving bomber. The results have not yet, however,been completely analyzed.

FIELD OF Vrmv.-The field of tiew from an air-plane cockpit or cabin is generally classified arbi-trarily by the occupant -as “good” or “poor.” Aninvestigation has been started to establish a suitablecriterion by which to rate airplanes in this respect.h apparatus has been developed for memuring theextent of the tiew from any seat in an aircraft andseveral service-type airplanes have already beenmapped. A report now in preparation will give datafrom a sufiicierit number of representative airplanwto make possible the development of a criterion fordeterminingg relative fields of view.

RAIN-VISION WrNDSmLD.-An inves~ation hasbeen completed in the 7- by 10-foot tunnel on a full-scale model of a cabin fuselage for the purpose ofexploring the possibilities of obtaining satisfactoryvision through open windows under conditions of rainand fog. The rain was simulated by a controlledspray located upstream from the fuselage. Testswere made with openings of various forms directlyforward and to the side, which resulted in a side-window arrangement which is inclined inward to givestraight forward vision and which can be completelyopened without the entrance of even large drops ofrain. A report is in preparation describing the testsand giving the proportions of the successful design.

SOURCESOFNOISE IN ArncRur.-The fundamentalresearch on the source and character of firopellernoise has been continued. During the past year thework has been cordined to a study of model propellers.The noise from such propelle~ has been analyzed andis found to consist in general of two groups of sounds.One group consists of a musical note whose frequencyis connected with the speed of rotation, with its trainof harmonics. The other group is composed of muchhigher frequencies, nonmusically related, which areundoubtedly generated by the shedding of vorticesfrom the trailing edge of the blades. The effect ofchanges in tip speed and angle of attack upon thesetwo types of sound has been investigated. Themanner in which the ear responds to noises of this sort,together with several possible methods of estimatingloudness, has been studied.

COMMITTEE FOR AERONAUTICS

VIBItAmON RHSDARCH.-TSStS with an airplane infloating suspension excited by a sinusoidal force werecontinued, the response of the fuselage and wings tothe various frequencies being studied. In the partic-ular airplane it was found that a large response oc-curred near the normal operating speed of the engine,In order to facilitate the observation of vibrations onall points of an airplane structure, a new instrumenthas been developed which permits instantaneous rend-ings, obvia~m laborious preparations and precautions.A number of tlight tests have been performed for thepurpose of idenmg vibrations of pure aerodynamicorigin. Preliminary tests on a biplane disclosed con-siderable disturbances of irregular @e in the range of400 to 650 per minute. These disturbances could onlybe observed at diving speeds or above the stalling angle;no vibrations that could be attributed to aerodynamicforces were recorded in normal tlight conditions.

ROTATING-Wmff lmwrwm.-Because of the possi-bility of obtaining sustentation with little or no for-ward speed and the consequent possibility of safe flightat low speeds, continued attantion has been givenduring the past year to three promising types ofrotating+ng aircraft.

The tit is the familiar autogiro in which the rotoraxis is vertical, the rotation of the rotor occurs auto-matically as a result of air forces acting on the rotorblade, and lift on opposing bladea is equalized by aflapping motion of the blades. Investigations havebeen made of the various elements controlling the per-formance of this type of machine, and one such inves-tigation, which consisted of determiningg the rotor blndemotions and the ditilon of load between the rotor andthe fixed wing, has been completed and described inTechnical Report No. 475. The results of this inves-tigation served two purposes: (1) The measured loadson the iixed wing have aided in the formulation of de-sign rules for the fixed wings of this type of aircraft,and (2) the load on the rotor correlated with the meas-ured blade motion has provided data needed for D the-oretical study of rotor characteristics, the results ofwhich are now being prepared for publication. A briefinvestigation of the vibrations occurring in rL3-bladeautogiro has also been completed, and flight tests arein progress for the purpose of dete rmining the effectof the incidence of the fixed wings on the rotor char-acteristic and on performance in general.

The second type of rotating wing being investigated,the gyroplane, is similar in general principle to theautogiro, but is fundamentally diilerent in regard toits rotor operation, in that opposite blades of the rotorare rigidly connected and lift on these bladea is equal-ized by oscillation about an axis parallel to the bladespan. A theoretical analysis of this type of machinehas been completed and is now in preparation forpublication.

REPORT NATIONAL ADVISORY

‘ The third type being investigated, the cyclogiro, de-rives its lift and thrust from a power-driven rotm con-sisting of several blades rotating about an axis parallelto the lateral axis of the aircraft. A theoretical anal-ysis of the cyclogiro haa been completed and a simpli-fied aerodynamic theo~ of the machine has beenprepared and published (Technical Note No. 467).The analysis indicates that the aerodynamic principlesare sound, that hovering flight, vertical climb, and areasonable forward speed may be expected with a rea-sonable expenditure of power, and that aut.orotationin a gliding descent is available in the event of enginefailure.

The studies on all three types of rotating-wing air-craft are being continued mainly in the form of wind-tunnel invmtigations principally for the purpose ofimproving the rotor characteristics of the autogiroand gyroplane and co- the soundnem of theprinciples involved in the cyclogiro.

Amamm.-Airship work has been contined to somemiscellaneous activities such as cooperation with theArmy in speed trials with the T(3II and TG13 air-ships, cooperation with the Navy in speed and decel-eration tests with the U.S. airship Muon, and theemplitication of previous reports to the Navy givingdata obtained in the trial flights with the U.S. airshipAkron.

SIWPLANES.-A descriptio~ of the National Ad-visory Committee for Aeronautics tank, or seaplanechannel, has been prepared and issued as TechnicalReport No. 470. Reference is made in the report tothe important items of equipment and the satisfac-tory behavior of the rubber tires, the towing carriage,and the towing gear. The research program has fol-lowed quite closely the program outlined in last year’sreport. Although emphasis has been placed on in-vestigations which have immediate application, theaddition of wave suppresses has greatly expeditedthe carrying out of the research program.

Efiecta of variation in dimewimw and form of hullon take-o$ oj$fing iioats.-The effects of variation indimensions are being studied by tests of a series offive models derived from a parent form by systematicvariations in dimensions. The five models were in-vestigated according to the general method in whichthe resistance, rise, and trimmhg moment of themodel are determined at various fixed trims over arange of speeds. The results show that the perform-ance of the parent model could be improved by chang-ing its form to give a longer and flatter forebody. Anew forebody was made and tested with the originalnfterbody, and the improved model equals in perform-ance the best flying-boat hull. Tests of two models,nos. 11 and 11A, are described in Technical NotesNOS. 464 and 470.

Observation of the behavior of the models of hullstested suggested the possibility of improving perform-

COMMFIT@llll FOR AERONAUTICS 15

ante by a radical ch~~e in the form of the main step.A model was prepared in which the step was muchdeeper than usual and was pointed in plan form in-stead of square across the hull. This model, no. 22,showed a general performance much superior to thepretious model. These results will be. issued as atechnical note and it is hoped that a full-scale test ofthis form may be made to determine ib behavior underoperating conditions.

A model of a flyimg-boat hull ha~~ one form ofBtub wings or sponsons to provide lateral stabilitywas investigated. Other forms of sponsons have beenmade for tests with the same main hull, and in view ofthe later development of this type of lateral stabiliza-tion, it is planned to extend the application to hulls ofother shapes.

~a48 jor wupf.am%.-ti order to obtain informa-tion regarding the performance of a good hi@-speedseaplane float, tests were made of a model of a floatused on the Macchi racer of 1926. As a result of thetests a float designed to be an improvement of thisfloat and to be used as a parent of futurp series wastested. This model showed a marked improvementover the Macchi float. The results of the two tes@ arecompared in Technical Note No. 473.

Fundamental informdioia regarding planing wr-@ce8.-For a large part of the take-off run of the sea-plane, that part of the weight of the craft not supported

by the wingg is supported by the hydrodynamic reac-tion of the water on the bottom of the float or boat.By testing surfaces that skim along the top of the watersimulating only the bottom of a float, much valuablefundamental information can be obtained. A seriesof test9 of planing surfaces consisting of flat surfacw at0°+ 10°,20°, and 30° dihedral h= been completed, andthe results are being prepared for issue m a technicalnote. A seriw of somewhat similar models consistingof two surfacw with transverse curvature set at vari-ous dihedrals is being constructed for use in furthertests. It is also planned to twt surfaces with fore andaft curvature at a later date.

The results of the tests of these models may makepossible the separation of the pure planing phenomenafrom the other factors encountered in tests of completemodels and thus give valuable clues as to the properform of bottoms.

Fridimuzl rmistmwe oj boai 8urjac+=-Frictional re-sistance of those surfaces of a boat hull which areexposed to the pas-sing water has not “been determinedfor speeds from 30 to 60 miles per hour. The surfac=for a series of tests of frictional resistance, with theirsupporting gear, are completed, and the surfaces foranother series nearly ready for investigation.

Spe@ic td jor Qouhunent w&.—A number ofinvestigations specifically requested by the Bureau ofA~onau@ have been conducted. An inves~mation

16 REPORT NATIONAIJ ADVISORY COMMM’TDEFOB ADRONAU’JZCS

of methods for the control of spray was made on amodel of a Navy flying boat. It was found that theaddition of spray strips gave some improvement, butin this particular case not as much as was desired.

At the requ=t of the &my Air Corps, extensiveteats were made of models of the hull of an amphibianflying boat to obtain information as to the water per-formance of the craft with various modifications.

BUREAU OF STANDARDS

WmD-TmN-EL hmmrr~Amor?s.-The aerodynamicactivities of the Bureau of Standards have been con-ducted in cooperation with the National AdvisoryCommittee for Aeronautics.

Apparatw for meawring iu.rbu?ence.-lhcause ofthe considerable weight and bulk of the present equip-ment for maid.ng turbulence measurements the possi-bilities of developing a light and easily porikible typeof instrument axe being investigated. The problem isbeing attacked by two principal methods: first, bysimplification of the present hot-wire type of appara-tus by eliminating the batteries, and, second, by thedirect measurement of forces on bodies such as spheresand cylindem.

CompuMwn OJboundwyhyer jbw.-A comparisonhas been made of the boundary-layer flow computedby the approximate method developed by Pohlhausanwith the more met solutions which have been pub-lished for several special cases. Approximate methodsof the type suggested by Pohlhausen are useful ingiving a picture of the flow in many cases, but theirrange of application is limited. A modification ofPohlhausen’s method has been developed which ex-tends the range of application and a comparison of theflow computed by this method with that of moreexact solutions shows that the range of application hasbeen increased at the expense of some decrease in theaccuracy of the approximation. A paper describingthe methods used in the computations has beenprepared.

Cup amnnometers.-An investigation of the effectsof turbulence on the speed indications given by theordinary hemispherical cup anemometer has been.completed. When disturbances in the air stream wereproduced by a turbulence screen consisting of a wirenet on which were loosely fastened small metal tags,the normal rate of the anemometer was found to beconsiderably increased. A s@%matic investigationhas been made of the effects of roughening the outersu.rhm of the cups.

AERONAUTIC hSTR~T hvwrrGAmoNs.-Thework on aeronautic instruments was conducted incooperation with the National Advisory Committeefor Aeronautics and the Bureau of Aeronautics of theNavy Department and included the investigations andthe instrument development outlined below.

Temperature coejhient of elw!ic nwduli.-The re-sults of this investigation were published in theBurtiu of Standards Journal of Research (R.P. 631)in March 1933.

Lubricuni.sfor instrument mechanti.-The essen-tial requirements of a lubrimnt for aircraft instrumentsinclude long life and operation at low temperatures.Mineral oils spread and therefore do not have a longlife in the bearing. On the other hand, animal orvegetable oils do not spread but gum moro or lessslowly. An investigation waa initiated to determinethe characteristics of the oils available, including thosewith antioxidant, with a view to the preparation ofspecihdions based on the performance of the beatlubricant. Tests are being made on samplea of about40 oils. In addition to the customary tests givenlubricants, each sample is being given two tests, theresults of which it is hoped to correlate: (a) An accel-erated oxidation test, and (b) a life test. The appma-tus for the life test consists of a bank of 50 watchbalance wheels, 3 or 4 of which me lubricatedwith the same oil, which are kept in oscillation by asnitible electromechanical device. The condition of .the lubricant in each balance wheel is checked fromtime to time by measuring and comparing the timefor the amplitude of the freely oscillating balancewheel to decrease horn a given initial to final value.

Reporb on aimrqft instrument8.-A report on aircraft.power plant instruments, including descriptions of,and performance data on, tachometers, thermometers,pressure gauges, fuel-quantity gauges, and fuel-flowindicators was completed and will be published asTechnical Report No. 466. Considerable progress hasbeen made on two reports similar in scope on blind-flying instruments and on altitude instrument.

New instrumem%.-A number of new instrumentswere developed and constructed. These developmentsinclude the following:

A superheat meter of the resistance type has beencompleted and installed in the metal-clad airship.ZMGI!. With this type a marked reduction in weightk obtained and a mbre rugged indicator can be usedRScompared with the thermocouple type.

+ alarm which operates when the indication ofcarbon monoxide exceeds 0.02 percent has beendeveloped and added to the M.S.A. carbon mono.xidoindicator.

An instrument was developed to indicate the levelof the liquid air in the helium puriiier apparatus. The[evel is indicated by the diilerential effect in the alter-cating currents fim two external coils produced by nfloat in the liquid camying a soft iron plunger.

An air-speed meter of the commutator-condensertype, the propeller and commutator unit of whichue designed for mounting on an airplane strut, was:ompleted.

REPORT NATIONAL ADVISORY

A fundamental modification has been made in theventuri fuel flow-meter which in the usual form hasbeen found to be unzatisfactxmy on airpkmcs. Airinstead of gasoline is used as the medium by which thed.Merential pressure developed by the venturi tube istransmitted to the indicator in the cockpit. Thedifferential pressure developed by the venturi tube istransmitted to two flexible elements the differentialaction of which controls a valve regulating the suctionwithin an air chamber. This suction is transnn“ttedto the indicator. Several designs have been prepaxedand one instrument constructed which is ready forflight tests.

REPORT OF COMMITTEE ON POWER PLANTSFOR AIRCRAFT

LANGLEY MEMORIAL AERONAUTICAL LABORATORY

COMPRESSION-IGNITIONEr?c+nms.-The advantagesclaimed for the compression-ignition engine of reducedfuel consumption and the maintenance of power ataltitude have been substantiated by recent flight testsof several compression-ignition aircraft enggnes. Thepower output per cubic inch of displacement of mm-pression-iinition engines, however, is still inferior tothat of conventional aircraft engines. The resultsobtained from an investigation of the performance ofcompression-ignition engimw with boosting have shownthat the increase in engine power with boosting is con-siderably less than that obtained with the carburetorengine. The research of the Committee has indicatedthut the method which holds the greatest promise forincreasing the performance of the compression-ignitionengine is to operate the engine on the two-stroke cycle.The investigation of the factors controlling the per-formance of a high-speed two-stroke-cycle single-cylinder compression-ignition engine has resulted inthe attainment of a power output per unit of displace-ment which is 27 percent greater than that obtainedwith pr~ent commercial aircraft engines.

Fuel 8pray cluwacteridic.s.-!l?he attainment of effi-cient combustion in compression-ignition engines isdependent upon the distribution of the fuel sprayswithin the combustion chamber. Previous investiga-tions of the Committee have shown that with fuelinjected from round-hole orifices the greater part of thefuel is concentrated in the spray core. The effect onfuel-spray distribution of breaking up the core of fuelsprays has been investigated by injecting a smallquantity of air at high pressure with the fuel oil.Spark photographs of the fuel sprays and measure-ments of the diameters of the oil drops in the sprayshowed that the use of the compressed air gave im-proved distribution and atomization of the fuel spray.An injection system incorporating this principle of fueldistribution was constructed and tested on a single-cylinder engine having a vertical-disk form of com-bustion chamber. The engine performance with thecombined hydraulic and air injection system was not

.

CO~El FOR AERONAUTICS 17

improved over that obtained with hydraulic injectionexcept at high air-fuel ratios. The results obtainedhorn the engine-performance teats indicated that withconventional hydraulic-injection pressures the atomiz-ation of the fuel was sufficient to result in goodcombustion. Additional methods of improving fueldistribution are to be investigated.

The penetration and distribution of fuel sprays fol-lowing the cut-off of injection have been invest@tidwith the National Advisory Committee for Aeronau-tics spray-photography a~pamtus. The object of theinvestigation was to obtain new knowledge concerningthe dktribution of fuel sprays for time intervals asgreat as 0.05 second after the cut-off of injection. Theeffects of air density, injection pressure, and air veloc-ity counter to the fuel spray, on the spray distributionhave been investigated. The remdts show that air-flow velocities from 15 to 25 feet per second directedcouni%r to the fuel spray are very effective in distrib-uting the fuel spray after injection cut-off, providedthe fuel is well broken up during the injection process.The effect of these low air velocities on the spiny coreduring injection is negligible.

Pintle-@pe fuel-injection nozzles have been used asa possible means of obtaining increased spray distribu-tion. During the year spark photographs have beentaken of fuel sprays from pintle nozzles. An analysisof the photographs shows that the a@e of the sprayfrom the pintle nozzle is approximately that of a sprayfrom a round orifice and that the angle of the pintlehas only a small effect on the spray angle. The pene-tration of the spray tip is comparable to that obtainedwith round-hole orifices. The results of this investi-gation are presented in Technical Note No. 465.

Injection-system chmwcteristiw-A fuel-injection sys-tem has been developed to give a l@h rate of fueldischarge and to give discharge characteristics that donot vary with engine speed. The energy for injectingthe fuel is supplied from a l@h-pressure reservoir atthe pump in which the pressure is built up previous tothe injection of fuel into the engine.. The injection ofthe fuel is caused by the sudden open@ of a pressurerelief valve, which permits a hydraulic pressure waveto be trans~tted through the tijecticm tube to theinjection valve. Injection of the fuel continue9 untilthe intensity of the pressure wave drops below theinjection-valve closing pressure. With this injectionsystem the period required for the injection of full-load fuel quantity for an engine having a bore of 5inches and a stroke of 7 inches and operating at aspeed of 1,500 revolutions per minute is only 10 crankdegrees. This injection system is being used to deter-mine the eflect of the rate of fuel injection on the per-formance of compression-ignition engine9.

An investigation has been made to determine theeffect of placing a reseivoir between the fuel-injectionpump and the injection tube connecting the pump to

18 REPOIKl? NATIONAL ADVISORY

the injection valve. The results show that the ratesof fuel injection can be changed considerably by theuse of such a reservoir and that the chattering ofinjection valve stems when a large discharge orilice isused can be prevented by using a rwervoir of thecorrect volume.

Combustion in compre.ssiw-ignition engiw3.-ALthough progress has been made toward decreasing theweight-power ratio of compression-ignition engines, thebest ratio obtained is still excessive when compaiedwith that of presentiay spark-iggtion aircraft en-gines. The decrease of this ratio is dependent uponan increase in the combustion efficiency of compres-sion-ignition aircraft engines. The National AdvisoryCommittee for Aermmutim spray-combustion appara-tus has been used to determine the effect of the timefor mkture formation on the course of combustion.The compression ratio used in the investigation was12.7. In the preliminary tests the ignition of the fuelat a deiin.ite time in the cycle was insured by using anelectric spark. The factors investigated were injec-tion-advance angle, engin=oolant temperature, en-gine speed, and spark timing and location. Indicatorcards were obtained with an optical engine indicator;continuous photographic records were taken of themovement of the combustion zone. These datashowed the course of the combustion to be a functionof the temperature and pressure to which the fuel hadbeen subjected previous to the ignition of the air-fuelmixture. At low air temperatures it was found thatthe rates of combustion varied with the volatility ofthe fuel, but at high air temperatures this relationshipdid not exist and the rates depended to a greaterestent on the chemical nature of the fuel. The resultsof this inves~aation are being prepaxed for publicationas a technicnl report.

The rapid rate of pressure rise and hisgh maximumcylinder prt=mms obtained in compression-ignitionengines are detrimental to smooth engine operation.The rate of pressure rim and mtium cylinder pres-sure are influenced by the time required for the fuelafter injection to absorb heat from the compressed airin the cylinder. Preliminary investigations conductedwith a cam-operated fuel-injection ptip and adiaphraggn-loaded fuel-injection valve showed thatpreheating the fuel to 330° F. before injection reducedthe ignition lag and the maximum cylinder pressure.For higher fuel temperatures the injection of the fuelbecame erratic. A conventional injection system hasbeen modified so that it functions independently of thetemperature of the fuel. Bench tests conducted withthe injection system showed satisfactory operat@characteristics for fuel temperatures of 900° F. Theengine performance obtained with this injection sys-tem is being determined with the system installed in acompression-ignition engine having a high-velocity airflow for distributing the fuel spray.

COMMITTEE FOR MIRONA~CS

Information relating to the composition of the fuelused, the air-fuel ratio, carbon monoxide content, andfuel wasted because of incomplete combustion moy bereadily obtained from an analysis of the exhaust gasfrom internal-combustion en=tiea. Research has beenconducted from five different engines to determine therelationship between hydrogen, methrme, and carbonmonoxide in the exhaust of four-stroke cycle enginesusing a large number of hydrocarbon fuels. It wasdetermined that a linear relation existed between thecarbon monoxide and the hydrogen found in the ex-haust gas from engines using hydrocarbon fuels. Asmall amount of methane was found to be alwmys pres-ent in the exhaust gas, but the amount was independentof the air-fuel ratio and of the hydrogen-carbon ratioof the fuel. These determined relationships and theuse of the Ostwald combustion diagram make availableall the information of a complete exhaust-gas analysiswhen any two factors (carbon monoxide content, car-bon dioxide content, air-fuel ratio) are known. Theinvestigation has been reported in Technical ReportNo. 476.

Hydrogen as an auxi.liuryfuel for compression-ignition~“nes.-The designers of airships are of the opinionthat the successful commercial airship must be poweredwith compression-ignition engines. The use of com-pression-ignition engges reduces the fire hazard andmakes it possible to operate ovor a wide range of mginespeeds with low specific fuel consumption. Additionallift and a reduction in weight of the water-recovery rLp-paratus used with helium would be obtained in com-mercial airships by the use of hydrogen stored withinthe helium cells. Since the hydrogen required to lifta given weight of fuel contains a quanti~ of heatenergy equal to 20 percent of the heat energy of thefuel, it would be desirable to utilize this energy indriving the. airship by burning the hydrogen in theenginm.

The Committee has conducted a research to deter-mine the quantity of hydrogen that can be inked withthe inlet air and burned in a compression-ignitionengine. A single+ylinder compression-ignition engineoperati~m at a speed of 1,500 revolutions per minutewas used in this investigation. The engge was oper-ated at compression ratios of 13.4 and 16.6. Theresults indicated that a suilicient quantity of hydrogencould be burned with all useful fuel-oil quantities tocompensate for the increase in lift due to the consump-tion of the fuel oil. Quantities of hydrogen from 6 to14 percent of the inducted air by volume could beburned, depending upop the engine conditions. Morepower could be obtained from the enggne when thecomposite fuel was used. At light lode the thermalefficiency was less than that obtained with fuel oilalone, but at full load the efficiency was greater withthe composite fuel. The engine could be stopped byslmtting off the supply of liquid fuel, since it ma found

..

REPORT NATIONAL ADVISORY

impossible to ignite the hydrogen-air mixture by com-pression. A report of this investigation is being pr-epared for publication.

Combustion4unnber inve.st@tion-In&gral type withno effective aw @w.-The reauhk of the investigationmade to determine the effects of scavenging the clear-ance volume and boosting on the performance of acompression-ignition engine with an integral combus-tion chamber having no effective air flow have beenpublished as Technical Report No. 469. ‘Ilk research,-conducted nt a compression ratio of 12.6, has been ex-tended to include the determination of the engine per-formance obtained at compression ratios of 10.5 and15.0. The engine+perating characteristics were foundto be quite diffenmt at these compression ratios. Ata compression ratio of 10.5 starting is difficult and theignition lag under standard test conditions is more thanone third longer than that obtained at a compressionratio of 15.0. The rate of pressure rise at the lowercompression ratio as determined from indicator cardsis nerwly double the correspond@ values obtained ata compression ratio of 15.0. Starting was easier at thehigher compression ratio and operation smoother, withmore uniform explosion prwures.

Combustion-cl&ber i&?&@ion-PTechamber twoe.- --with high-velocity air jfow.-Progremive changes madeto the shapo of the pre6hamber and of the connectingpassage have resulted in an 18 percent increase in thebrake horsepower developed by a single+ylinder com-pression-ignition engine when operating with the theo-retical full-load fuel quantity and with an engine speedof 1,500 revolutions per minute. The results of pre-vious investigations indicated that improvement inperformance was the result of intensification of the airflow, and the first change in shape was the use of apaasage tangential to the spherical chamber instead ofthe radial paasage that had been used for the purpose ofsymmetry in prem.ous investigations. The tangentialpassage caused a forced rotation of the sphere of air inthe chamber which persisted during injection and com-bustion of the fuel and improved the engine perform-ance. The tmgential pas-sage was tested as a straightpassage and also as a tapered flared passage. Bestresults were obtained with a passage slightly flared atth? cylinder and tapered toward the prechamber.

As a further means of intensifying the air flow,the auxiliary chamber shape was changed from asphere to a disk with rounded edges to eliminate thecomparatively low-velocity air at the poles of the rotat.ing sphere. This change in shape was effective inincronsing the engine power. Changes in the directionof the connecting passage in an attempt to produce anair swirl in the cylim+er seemed to have no beneficialeffect. The use of three passages diverging horn thecylinder, however, resulted in smoother engine oper-ation, although the performance vi-aa slightly inferior$0 that obtained with the single passage. An increase

COMbH’ITEE FOR AJ3RONAUTICS 19

in the fuel-spray penetration obtained by increasingthe length-diameter ratio of the injection-valve orificeborn 2.5 to 6.0 resulted in a slight increaae in power .output.

Two-stroke cycle investigation.-!l?he use of the com-pression-iggtion engine as a power plant for airplanesis dependent upon obtaining a power output per cubicinch of displacement comparable to that obtainedwith the conventional spark-ignition aircraft engine.A method of increasing the power output of compres-sion-ignition engines k to operate engine9 of this typeon the two-stroke cycle. The factors affecting theperformance of a two-stroke-cycle compression-ignitionengine are being investigated with a single+ylinderwater-cooled engine hnving a 4.625 -irLch bore and a7-inch stroke, and operating at a maximum speed of1,800 revolutions per minute. The factors investi-gated include the distribution of the fuel spray, thescavenging air pressure, the engine speed, and theinjection timing. The variation in fuel-spray distri-bution was obtained by varying the size, number, andarrangement of the fuel-valve ofices and the numberand position of the fuel-injection valv~.

Based on the results of these tests a si@e injectionvalve having a three-oriiice nozzle was selected forcontinuing the tests. With increaae in the scaveng-ing air pressure the brake mean effective pressureincreaaed linearly to 152 pounds per square inch at apressure of 3 pounds per square inch and a speed of1,250 revolutions per minute. Performance tests atvariable speed emphasized the importance of obtain-ing proper scavenging and charging of the enginecylinder. A description of the two-stroke-cycle testengine and the results of the preliminary engine testsare being prepared for publication.

FIRE HAZARD IN Amcum-Hydrogenated safetyfuek.-The investigation of the engine performanceobtained with a hydrogenated safety fuel injected intothe engine cylinder has been continued, a fuel havinga flash point of 125° 1?. and an octane number of 95being used. The performance of a single-cylinderliquid-cooled engine has been determined with thehydrogenated safety fuel for compression ratios of5.85 and 7.0, valve timings giving 30° and 130° overlap,inlet pressures horn atmosphmic to 5 pounds persquare inch boost preasnre, and engine speeds from1,250 to 2,200 revolutions per minute. The bestresults were obtained by locating the single injectionvalve between the two exhaust valvw so as to directthe fuel spray horizontally across the combustionchamber against the incon@ air. The duration offuel injection was from 60 to 70 crankshaft deggeesand tho start of injection from 70° to 90° after topcenter on the suction stroke. At a compression ratioof 7.o, a valve overlap of 130 crank degreea, a speedof 1,750 revolutions per minute, and a boost pressureof 1 pound pm. square inch, the brake mean eilective

20 REPORT NATIONAL ADVISORY

pressure obtained was 175 pounds per square inch andthe corresponding fuel consumption 0.50 pound perbrake horsepower per hour. In general, for similarconditions the power obtained with the safety fuel wcsequal to that obtained with gasoline, although the fuelconsumption with the safety fuel was 5 percent greater.The investigation has been described in TechnicalReport No. 471.

INCrmMEI m ENGINE Pomm—rwease in engimspeed.-The two principal methods of increasing thepower output of conventional aircraft engines are toincrease the brake mean effectvie pressure and to in-crease the engine rotative speed. The performanceobtained with the Committee’s singleeylinder testengines has been limited to maximum speeds of 2,2oorevolution per minute. In order to extend theinvestigation on boosting to higher boost preswresand higher engine speeds, a si@-cylinder liquid-cooled test engine has been designed and constructedto operate at a mtium speed of 3,OOOrevolutionsper minute and rLmaximum explosion pressure of 1,500pounds per square inch. A system of geawlrivencounterweights is used to bnkmce the engine. The

- test engine has been assembled and motoring testsof the engine am in progress.

COWLING AND COOLINQ OF h~ ENQINES—Cooling propertti of jinned swfa.ctx.-The demand forengbs of higher power and the general use of theNational Advisory Committee for Aeronautics codingor of ring cowlingq on airplanes has necessitated a studyof all potible methods for improving the cool@ ofair-cooled engges. An investigation to determine theeffect of fin pitch, fin width, and average fln thicknesson the temperature distribution in and the heat diwi-pation hem steel cylindem having tapered fins has beencompleted. The rarge of fin pitches investigated wasfrom 0.1 to 0.6 inch, the range of iin widths from 0.37to 1.47 inches, and the range of average iin thicknessfrom 0.04 to 0.27 inch. The cylinder diameter wasmaintained constant at 4.5 inches. The +~e of airspeeds investigated was from 30 to 150 miles per hour.The experimental data obtained have been used as thebasis for the development of a method for determin@fin dimensions permitting the use of a minimum ofmaterial for a rn~~e of conditions of heat transfer, airflow, rmd fi materials. The results of the invesl@a-tion will be made available in technical reports now inpreparation.

Research has been conducted with several tiedspecimens enclosed by a shroud. A blower was usedfor supplying the cool@ air and a Durley oriiice boxfor mensur+hyg the air quantity. In thwe tests theeffects on the heat transfer from the finned cylinder tothe cooling air of a range of air densities from 0.0476to 0.072 pound per cubic foot, cooling air temperaturesfrom 113° F. to 192° F., and air speeds ilom 10 to 150miles per hour have been investigated. For the

COMMITTEE FOR AERONAUTICS

cylindem tested the cooling was found to be propor-tional to the mass flow of the air raised to the 0.45power.

The use of deflectors for directing the cooling air tothe rear of the cylinder, thus increasing the amount oftied surface in contact with the cooling air, has beeninvestigated with an electrically heated finned speci-men mounted in a wind tunnel. In these teats it wnafound that the cylinder temperatures in the rear couldbe reduced 25 percent by the use of a sheetimetaldeflector in contact with the fin tips. The best resultswere obtained with this deflector when the front edgeof the deflector was from 70° to 90° from the front ofthe cylinder and the rear opening was large enough notto restrict the air flow. A duct about 3 inches longconnected to the rear of the deflector appreciablyimproved the cooling. Welding the deflector to thefins increased the tied surface that dissipated heatto the air stream and appreciably reduced the cylindertemperatures. This investigation is to be extended toinclude tests of the more promkii deflector and cyl-inder combinations at a range of air speeds from 50 to200 miles per hour.

The design of the National Advisory Committee forAeronautics cowling could be placed on a more rationalbasis if the minimum quantity of air required to coolsatisfactorily a given design of engine cylinder and thepressure differences available for forcing the air throughthe cowling in flight were known. The minimum quan-tity of air required to cool satisfactorily a conventionaldesign of engine cylinder is being determined with asingk+cylinder test engine. The cylinder is shroudedand the cooling air supplied by a blower. The qurm-tity of cool.iqg air and the pressure drop through thecowling are being measured for a wide range of engine-operating conditions. The effect of vmying the shapeof the entrance and exit openings in the cowljng on thequantity of air and pressure drop through the cowlingare be~o investigated by the aerodynamics divkion bymeans of models of the cowling mounted in a windtunnel.

Tmrow radid engine.-At the request of the Bureauof Aeronautics, Navy Department, the Committee hasdetermined the effect of air speed, engine power, andengtie speed on the temperature distribution obtain$dwith a two-row radial engine installed in a serviceairplane. The airplane was tested in flight and in thefull-scale wind tunnel. The temperature distributionover the engine was investigated by means of 47 small-diameter wire the~ocouples and two recording pyrom-eters. Thirty’ of these thermocouples were used todetermine the temperature distribution over tworepresentative cylinders, one in the front row and onein the rear. The effect on the cooling of the attitudeof the airplane and of the number of propeller blndeswas also invedignted.

REPORT NATIONA3 ADVISORY COMMITTEE FOB AERONAUTICS 21

INSTRUmNTS-Hti dynamometer.-The NationalAdvisory Committee for Aerommtica hub dynamome-ter has been designed to measure and photographicallyrecord the torque developed by an aircraft engine inflight. During the past year work has been directedtoward improving the torque-cell diaphragms. Theoriginal diaphragms machined from bar stock havebeen replaced by diaphragms machined from die forg-ings. Flight tests made with the dynamometer for arange of altitudes from sea level to 15,000 feet gavevery encouraging results. The engine power as deter-mined in flight was in good agreement with the calcu-lated engine power obtained by correc~~ the sea-levelbrake horsepower for the pressures and temperaturesat altitude. The temperature of the liquid in thetorque cells was found to be the same as the free-airtemperature and this fact will simplify the correctionfor temperature at high altitudes.

Engine {ndic.ahws.-The incensing demand for pres-sure records from spark-ignition and ccmpression-ignition engines requires that the precision and reliabil-ity of the pressure-recording apparatus be increased.Modifications of the Farnboro engine indicatcr used bythe laboratory- have been continued and the pressureelement will now operate continuously under desirableengine-operating conditions. The length of service ofthe disk has been increased by eliminating the arcingat the disk rmd seats. The low-pressure portion of theengine cycle is being studied with the aid of n sixobo-scopic valve, designed primarily for obtaining gassamples from an engine cylinder.

A new optical indicator which records photographi-cally the variation in pressure with time has beendeveloped for use with the N~tional Advisory Com-mittee for Aeronautics spray combustion apparatus.The large windows in the combustion apparatus permitthe use of a diaphragm having a diameter of 2 inches.The measured frequency of the diaphragm, mirror, andmirror staff is approximately 9,OOO vibrations persecond.

BUREAU OF STANDARDS

Mthde test8 of aircra$ en@aes.-AMtude teats of aCurtiss D-12 engine, in which the jacket water outlettemperature was varied over a range of nearly 70° C.,showed that friction decreases and fuel economy im-proves at all altitudes as the temperature of the jacketwater is increased. At sea level and low altitudes thepower output decreases with increasing jacket=watertemperature, but at high altitude-s the brake horsep-ower increases on account of the predominant effect

, of the decrease in friction. A report of these tests willbe published as a technical note.

Pistons giving compression ratios of about 6,7, and 8were obtained from the Army Air Corps for use instudying the effect of compression ratio upon the varia-

tion of horsepower with exhaust pressure, and the runsat one cemprwaion ratio have been completed.

Phebmenu of combustion.-A detailed study wasmade of the effect of water vapor on the speed of flamein space in equivalent mixturca of carbon monoxide andoxygen at low pressures. Among numerous rem.dts ofthis investigation it was found in particular that, forlow-pressure explosions of these gases, a moderateincrease in the amount of water vapor was sufficientto double the flame speed, and that the greater thepressure of the active constituents the greater was theaccelerating action. These facts indicate that thecontrol of the water-vapor content in mixtures ofcarbon monoxide and oxygen is very important in anyinvestigation involving measurement of flame speed.Provisions were made for adequate control of this factorin new apparatus which has been built for continuingthe study of gaseous explosive reactions.

C&tion in an engine qylinder.-Measurementshave been made of the variations during combustion inthe intensity and spectmd distribution of the radiantenergy (to llIL) emitted by the flame at two widelyseparated points in the eigine combustion chamber andunder a variety of operating conditions. The series offilters used in obtaining spectral distributions for theengine flames was used also in maid.ng supplementaryobservations of the radiation from a black-body furnaceat diflerent temperatures and from burner flames ofdiverse fuels.

Preliminary analysk of these data indicates that thegreat bulk of the energy radiated by the engine flameis in the infrared and exhibits strongly under all condi-tions the characteristic emissions of water vapor andcaxbon dioxide, while radiant energy horn incandescentcarbon is relatively weak and insufficient to serve as abasis for estimating flame temperature. Althoughtotal radiation varies greatly during an engine cycleand considerably for diilerent operating conditions,spectral distribution shows little change over a widerange of conditions. In a normal explosion, radiationbegins to increase upon arrival of visible flame undera window tmd continues to rise for 20° or more ofcrank movement thereafter, which indicates that reac-tions producing highly active molecules of water vaporand carbon dioxide continue to a considerably greaterdepth behind the flame front and for a longer period ina given tit of charge than is generally supposed. Ina knocking explosion, these reactions apparently arecompleted much more rapidly after inflammation inthat part of the combustion chrunber which is remotefrom the spark plug.

Prmsur~ and temperaiums in aircraft en@.es.-Apressure element of the balanced-diaphragm type hasbeen constructed for use on the C.F.R. research engine.The design incorporates certain experimental featureswhich may prove useful in attaining the high degree of

22 REPORT NATIONAL ADVISORY COM3U’ITEE FOR AERONAUTICS

simplicity and compactness necewary to the construc-tion of a reliable combination spark plug and pressureelement for aircmft+mgine use. Mtium diaphragmdiameter and provision for adjusting the zero readingwhile the indicator is on the engine also were incor-porated in the present element to give high accuracyin studying low-pressure phenomena, while the pas-sages between @e diaphragm and the engine com-bustion chamber were made very ‘short to preventdistortion of the peaks of the indicator diagrams.

Ignition re.eearch.-The ignition laboratory has beenengaged in various confidential investigations for theBureau of Aeronautics, Navy Department. Furtherwork has been done on the problem of measuring theelectrical characteristics of the spark discharge and apaper on the character of spark dischqys is beingprepared for publication in the Bureau of StandardsJournal of Research. An improved type of low-capaci-tance ignition cable has been developed which over-comes one of the main objections to shielding from theignition standpoint. Apparatus has been devised forcomparing the effectiveness of diilerent types ofshielding as regards radio reception. The study ofhydrocarbon oxidation has been continued and amethod has been perfected for obtaining photographicrecords of the changas in absorption which occur duringn single engine cycle w-hen a beam of light is painedthrough the combustion chamber of an engine.

Detonation raiing of am-don gmolina.-The CJ?.ILMotor Method, which is in general use for the knockmth.g of motor fuels, has been recmnrmmded for use inrating commercial aviation gasoline-s pending theadoption of a C.F.R. Aviation Method. A program ofmulticylinder engine tests to ascertain how muchtetmethyl lead or benzol in certain typical base fuelsis required to match the detonation chamcteristics ofthree reference fuels (rated, respectively, 73,80, and87 octane number by the C.F.R. Motor Method) hasbeen adopted and the tests will be made by the Bureauof Standards in cooperation with four engine manu-facturers. Each of the five laboratories will userepresentative commercial or militarg aircraft enginesand the average performance of the diverse test fuelswill give a basis for developing a suitable laboratorymethod of rating avktion gasolines.

Ice formaiion in tb indudion &ystenwof aircra$engina.-A study of the relation of fuel volatility toice formation in the induction systems of aircraftengines was undertaken in December and is nearlycompleted. The fuels used included three conventionalaviation gasolines, selected to cover the commercialvolatility range, and three aviation natural gasolines,diffe~~ widely in volatility. Small+cale tests at sealevel and at altitude, using a thermally insulated car-buretor through which conditioned air was drawn bymeans of a Nash pump, showed that it was possible topredict quite accurately the atmospheric conditions

under which a fuel would crmse ice formation in thecarburetor from a lmowledge of the distillation curveof the fuel and the supplied air-fuel ratio. Full-scaletests with a Curtiss D-12 engine mounted in thealtitude chamber verified the results obtained in thesmall-scale tests, ice being formed at the same venturitemperatures in each case within a few degrees.

REPORT OF COMMITTEE ON MATERIALSFOR AIRCRAFT

SUBCOMMITTEE ON METALS

In&mry8tal.line an.battlement oj sheet duralumin.—A report entitled “The Weathering of Sheet AluminumAlloys Used in Aircraft”, which summexizes the resultsof exposure tests of 5 years’ duration has been preparedfor publication as a technical report. The tests inwhich were obtained the data upon which the reportis based were conducted upon both commercial alloysand special compositions by exposing them continu-ously to the weather at three locations: Washington,D. C.; Hampton Roads, Va.; and Coco Solo, CanalZone. The resulting changes in the tensile propertiesas determined at intervals of several months during theduration of the tests have beon used as the principalmeasure of the corrosive effect by comparison with thecorresponding properties of similar materials care-fully stored under noncorrosive conditions. Thechange in the product of tensile strength and elongationexpressed as a percentage of the original was found to bevery useful for this purpose. All specimens aftercorrosion were examined as to the character of anycorrosive attack which had occurred and its relation tothe microstructure.

In addition to showing the useful life which may beexpected of the various materials under diil’erent cli-matic conditions, the investigation has clearly estab-lished a number of important facts relating to (a)the underlying causes of intercrystdine embrittlementof durahunin, (b) the most desirable method of heattreatment for developing reliable material having thehigh strength required, and (c) the dependability andusefulness of various protective coatings and surfacetreatments.

Numerous advances have been made in the devel-,opment of light alloys since the exposure tests referredto above wcire staxted. Early in the year a secondseries of tests intended tc cover a 5-year period wasstarted. The general plan is similar to thmt of thetests just completed, with a few improvements, how-ever, prompted by the fit series. Considerableprogress has already been made in the testing of thespecimens removed at 3-month and 6-month intervrdsfrom the racks. The. materials included in the testsrepresent 19 aluminum-base alloys and 9 magnesium-base alloys. Fifteen hundred specimens hove beenused at each test location. Fourteen metho+ for

REPORT NATIONAL ADVISORY

surface tredment and 12 diiTerent types of coatingsare represented. Close cooperation has been givenby the mmmfact~ers of the rn.aterials as well as of thevarious cording materials whmh form a part of thetest.

Exposure km% oj magmwium and magnesium a.?loy8.—Observations on materials in sheet form and as thincastings exposed continuously to the weather havebeen continued. The average change in tensilestrength of the sheet material after 4~ years’ exposureto the weather at Washington was of the order of 15percent. Most of the surface coatings failed within1X years. Outstanding exceptions wem aluminum-pigment spar varnish and an “acid-seal” coating on ared-lead primer. With the completion of the 5-yearperiod, all bf the specimens will have been tested and areport will be prepared. As part of the new series ofesposure tests mentioned above, various magnesiumalloys’ have been included. These will furnish infor-mation on the dependability of the materi@ underseacoast conditions.

Protection of durahmin, a~dic oxidiziion.-Thepractical value of trem%g the surface of durahninparta by an anodic oxidation process is now generallyrecognized and specified in airplane construction.Study of the various electrolytic methods used for thispurpose has been continued and has resulted in im-proving and simplifying the method considerably. Anumber of modifications of the usual chromic-acidsolution have been developed and progress has been

. made in the explanation of the deterioration of theelectrolytic bath during use, whereby the surfaceoxide ilh.n formed in treatment of successive lots is 1-and less effective. Close contact with the NavalAircraft 11’actory has been maintained.

Airplizne propel.lem-ziluminurn aUoy.-The con-tinued sporadic failure of propeller blades constitutes aserious problem to aircraft. During the year 8 alu-minum alloy blades, 4 with hub failurea and 4 withblade failures, were studied. All were fatigue frrLc-tures. Those at the hub originated at the peripheryapproximately in line with the trailing edge. Themetallurgical examination did not reveal any significantdefects in material nor heat treatment. Stresses as-sociated with the method of clamping the blades in thesteel hub appear to have more bearing on the hubfailures than defective material.

Failures in the blade itself, beyond the hub, origi-nated on the flat side of the blade, the fractures beingsuggestive of a coarsely crystalline brittle metal.Ordinarily fatigue fkctures in aluminum alloys haven comparatively smooth surface. Preliminary experi-ments have indicated that fatigue cracks formed in thealuminum alloy blades by a few thousand cycles ofreversed stresses greatly in excess of the fatigue limitwere similar in rLppearame tO those formed in theblades that failed in service.

COMMITTED FOR AERONAUTICS 23

In the examinations of the metals of the failed bladestwo rather unusual types of metaUographic markingswithin the structure of individual grains were discov-ered, one being a veined structure and the other criss-cross or “slip-line” markings. The cause and signifi-cance of these markings have not yet been determined.Both have been eliminated by suitable heat treatmentand neither appeam to have a marked efkct upon thetensile propertk of the material.

Airplane pmpellerAeeL-Examination of the frac-ture of a failed welded steel propeller reverded a fatiguefracture, associated with a defect in the weld on theleading edge. Other portions of the welds in thisblade and some other similar blades showed defects ofvarious sorts.. A study was made of nondestructivemethods applicable to the inspection of such bladw.The use of a magnetic powder dusted on the magnetizedblades was considered to be most practicable. It wasfound that this method revealed some defects whichwere not shown by an X-ray examination.

A thorough study was made of hollow welded steelblades furnished by the manufacturer and a detailedreport prepared describing the necessary technique tobe employed and illustrating the patterns formed bythe various defects. This report was intended for theuse of inspeckms in routine inspection in the field andin the manufacturer’s plant. The information wassupplied to the Aeronautics Branch of the Departmentof Commerce, the Army Air Corps, and the Bureau ofAeronautics of the Navy.

SUBCOMMITTEE ON AIRCRAM’ STRUC’JTJRES

.ln.ela.eticbeluuior of dum.zluminand alloy steels in ten-sion and compremion.-A procedure has been developedfor the determination of the stres-stmin properties incompression of sheet and thin-walled structures. Inthis test a number of coupons are cut from the materialand placed together like leaves in a book. Bucklingof the, outer leaves is prevented by a number of steelstuds inserted between the specimen and an auxiliaryframe. The preliminary tests indicate that values fora yield point can be obtained which can be repeatad bydiilerent observers and, in the case of coupons cut fromtubing, compared with values obtained in the test oftubes with a length-radius ratio of about 15.

End jixution of M*.—The laboratory work onround normalized or annealed chromium molybdenumsteel, duralumin, and high-strength stainless-steeltubing has been completed. Formulas similar to thoseby Orrin E. Rosa published in Technical Note No. 306of the National Advisory Committee for Aeronauticshave been developed, which represent with a gooddeg~ee of accuracy the relation between the columnstre~ths and the geometric properties of Navy stand-ard steel tubes and S.A.E. standard duralumin tubespassing Navy Department specifications for the tubingtested. From these formulas curves have been drawn

24 REPORT NATIONAL ADVISORY

giving the axial load which can be carried by any stand-ard tube of any free length up to 200 timm the slender-ness ratio or 200 inches, whichever is the smaller.

Friedrich Bleich’s method of designing compressionmembers with elastically restrained ends has been ex-tended so that it is now possible in trusses to designsuch members against buckling in the plane of thetruss with considerably greater accuracy than before.The method consists wsentially, after making a pre-

- d~@, b assum.@ as freely supported thefar ends of all members meeting at either end of amember to be designed iinally, and then determiningthe free length of the latter. A nomographic charthas been worked out which materially assists in thisdetermination. When the free length has been found,the rest is merely a matter of selecting the propersection, either by the use of the appropriate columnforfnula, or from the corresponding load-free-lengthcurves.

Tortinul strength of tubing.-The report on thetorsional strength of chromium molybdenum steeltubing, which has been prepared in manuscript form,is being held in abeyance awaiting the results of theparallel program on 17ST dnralumin tubes.

The experimental part of this latter program hasbeen completed. Tubes of the following sizes areincluded: l-inch diameter, 0.018 to 0.120 inch thick;l-inch diameter, 0.022 to 0.220 inch thick; and 2-inchdiameter, 0.022 to 0.220 inch thick. Torsion testswere made on tubes 20 inches and 60 inches lo~m ofeach size; tensile and hardn- tests were also made ontubes of each size.

It is planned to present the results of these tests assoon as they have been analyzed as the second part ofa report on torsional strength of tubing, thus includingin one report tubing of the two materials principallyused in aircraft dwi=m.

Strength of rimted joinfs in aluminum aUoy.-Themajority of the tasting thturw and tlm heat-treatingequipment ha,ve been constructed for this investigation.Tests have been made to determine the effect of holeand plate clearances in doubh+shear teds of the rivetstock. Tests have been started to determine theoptimum driving pre.wmre for a given rivet size, platethickness, and grip, but these have not yet progressedfar enough for deihita conclusions to be given.

Vibrai%n t&8 of propeUer8.-Thi5 investigation wasundertaken in cooperation with other agencies of theGovernment in an attempt to gain a clearer under-standing of propeller failures in flight. Most propellerfailures are found to proceed from typical fatiguecrack which in turn must be due to l@h periodicstresses. The source and nature of these stresses arenot known. It is not clmr whether they are due toresommce vibrations of large amplitude superimposedon the steady sties due to the cenhifugal forceswhether they are due to purely forced vibrations.

or

COMMITTEE FOR AERONAUTICS

No answer to these questions can be expected untilit has been shown whether or not either resonancevibrations or forced vibrations of suilicient amplitudecan be maintied in a propeller to cause failure. Itwas therefore decided to begin the investigation bydeveloping a method of exciting vibrations of con-trollable frequency and amplitude in the propellar, ofmemuring the stresses set up during this vibration,and, if possible, of producing fatigue failuroa.

Of the various methods considered the following waasuccessful in accomplishing its purpose. A direct-current motor has its armature connected across analternating-current source of variable frequency whileits field is excited by a steady direct current; the rotorof the motor then performs torsional vibrations of thefrequency of the armature current and an amplitudethat may be controlled by controlling the field currentor the impressed alternating voltage. This torsionalvibration is transmitted through the shaft of the rotorto the propeller blades, which are mounted in u hubat the end of this shaft in the same way as an airplanepropeller is connected to the crankshaft of its drivingengine. The propeller executes a forced vibration,which becomes large whenever the impressed frequencycoincides with one of its natural frequencies.

In the new equipment, which was installed afterpreliminary tests had shown the method to be practiord,the impressed frequency mriy be varied from 10 to 180cycles per second. As the frequency was increasedgradually from its lowe9t value the fit rwonancevibration was observed between 30 and 40 cycles; thepropeller blade vibrated approximately as a cantileverbeam tied at the hub end; a careful determination ofthe stress distribution in this mode was made, using2-inch Tuckennan optical strain gages having a specialheavy lmife edge to reduce inertia effects. The stresseswere found to vary linearly with the deflection of thetip of the blade. This result was utilized in makingfatigue tests on eight propeller blades. The bladeswere run at a given tip amplitude, corresponding to amaximum stress amplitude given from the strain-gagemeasurements, until failure occurred. This failuretaok place in each of the eight blades by the formationof a crack at a point C1OS6to the observed stress maxi-mum, which was 20 to 30 inches from the center of thehub of the propeller. The results were plotted on adiagram of logarithmic stress versus number of cyclesto failure. However, the number of points was notticient to draw definite conclusions. The torqueamplitude causing failure was of the order of 100 ft.-lb.

As the frequency was increased beyond the pointcorresponding to the fundamental described above, ntorsional resonance vibration of the whole propellerabout the driving shaft was passed at around 60cycles, and finally at around 110 to 130 cycles a furtherbending vibration of the individual blades waa reached,this time with a node about 9 inches from the tip.

,

RDPOET NATIONAL ADVISORY COMMITI’DE FOR AERONAUITCS 25

The stress distribution for the mode was obtained forone blade and showed a mtium a few inches from thenode.

The e.sperimental investigation has been paralleledby n theoretical analysis. The stress distribution in apropeller of given design vibrating with its funda-mental frequency was calculated by a method of suc-cessive itcmtion lirst applied to propelkm by Hansenand Mcsmer (Z. I?.M., vol. 23, 1933). This gave aclose check with the observed frequency and with thestress distribution obtained by the Tuckerman gages.The same method has been modified to compute thenatural mode, frequency, and stress distribution due tothe first harmonic with node near the tip.

The Mat6riel Division of the Army Air Corps hasconducted a study of the resonant-vibration fre-quencies of propeller blades, using entirely ~erentmethods and equipment. The results of this investi-gation have been published (Air Corps TechnicalReport No. 3891); and show in general that the failuresof propellem were due to the coinciding of the resonwt+vibration frequencies of the propeller blades with theengine-explosion frequencies.

Airship gira% and aw8hip structural nwmb6r8.-Anumber of column tests have been made on two experi-mental and two production plate airship girdem ofaluminum alloy fabricated by the Goodyear-ZeppelinCorporation. These tests were made in the largeEmery testing machine. The specimens were placedin the machine to simulate as nearly m practicable flatend columns. The lowest maximum load recorded forany of the specimens taken from the production girdemwas 27,450 pounds for a column 103.4 inches long.The determinations of the areas of the chord membersare in progress.

Specimens of the original German duralumin latticesand channels from the airship Lm Angel% have beensubmitted at intervals throughout the year. Theresults of the tensile tests on lattice and channelm~terial do not suggest that there has been any ap-preciable progress in corrosion during the last year.In no piece tested was the corrosion sufficient to lowerthe strength of the ship.

A number of specimens of thin sheet Alclad cut fromthe hull plating of the airship MC-2 have been testedin tension. The results of these tests do not suggestan appreciable deterioration M a result of corrosion.No hull specimen showed ultimate strengths of lessthrm 64,900 pounds per square inch or elongations leasthan 15 percent.

The investigation of the stresses in wire loops hasbeen continued. Studies have been made of thefirtctures of bulkhead fork wires. These fractuma areattribute d to fatigue. A satisfactory procedure fordetermining the residual stresses in wire helixes hasbeen obtained. The determination of these stressesis proceeding as opportunity dords.

4076~

Flut plutm under nornud preawwe.-The analysis ofresults from a detailed test of a 5 by 5 by 0.02 inchdnralumin plate with clamped edges led to the follow-ing tentative conclusions:

The only lmown theory which gives a roughly ade-quate picture of the behavior of a plate of this type isthat of l?oeppl. The distribution of median planestresses is roughly the same as that given by Foeppl;that of the bending stresses is very different. Themagnitude of the ~uln totfd StrCSSwhich OCC~at the middle of the edge of the plate is 10 to 20 percenthigher than that predicted by Foeppl.

By the application of Foeppl’s theory it can beshown that all curves of pressure versus center deflec-tion obtained from tests of square plates of a givenmaterial with fixed edges can be reduced to one curveif the pressures are divided by the fourth power ofthe ratio of the thickness of the plate to its width,and the center deflection by the thickness alone.This cum% w-as computed for square duralumin plateswith logarithmic paper and it was found that all theobserved curves when reduced come fairly close to thiscurve throughout the elastic range.

A number of stainless-steel plates have been testedunder nor.b.ml pressure; they showed the same be-havior qualitatively as the duralumin plates reportedon above.

Following a lead &m an article in Z.V.I., vol. 26,1932, a varnish was developed which cracked under ntensile strain from 1.3 to 2.310-3 in.~in. correspondingto stress well below the yield point for dnralumin.Rectangular dnialumin plates were coated with thisvarnish and the formation of the deiinite strain pahtern that developed as each plate was subjected to in-creasing normal pressure was followed; this strainpattern showed directly the extent to which the clamp-ing at the short ends aflected the stress distributionand it also showed the curve near the edges along whichthe surface strains reversed from compression totension.

S’irength of welded joim% in Mndar members forawcraft.-Tests have been completed on the majorityof specimens of the second series of this investigation.A series of 216 butt-welded tensile specimens inchromium molybdenum plate 0.0325 inch to 0.1875inch thick has been tested to determine the strengthsobtainable in joints heatitreated after welding forthree types of %kling: The stzmdard procedure usinglow-carbon rod; welding with chromium molybdenumrod; and “ carburizing flux” welding.

Joints made by these three methods and testedwithout having been heat-treated had about the sametensile strength. Of the heat-treated welds thosemade by the standard procedure showed less tensilestrength than the chromium molybdenum and the car-burizing flux welds. The last $ype showed somewhathigher tensile strengths for all heatitreated specimens

26 REPORT NATIONAL AD~OllY

of 0.0325 inch thiclmew and in general for all the thick-nesses tested, except at the lowest drawing temper-ature, 5000 F.

Tests made on T-joints in both carbon and chro-mium molybdenum steel tubing of 1.5 inches outsidediameter by 0.058-inch mill, show the inserted-gussettype of reinforcement to be the best consideringstrength, S**, -weight, and ease of welding.

Tests are being continued on tubular joints heat-treated after welding and on joints made in tbin-walled tubing of 1.5 inches outsido diameter by 0.020-inch wall.

TEMPORARY SUBCOMMITTEE ON RESEARCHPROGRAM ON MONOCOQUE DESIGN

STEEssmA3D, OR MONOCOQUE, STEucTURm.—During the past year, r=earch on stressed-skin, ormonocoque, structures for aircraft has consistedlargely of fundamental studies concerning the strength

. and behavior of skin and stiffeners. Where possible,such phases of the general subject have been sum-marized in useful form for the de-signer.

In order that the industry and others interestedin research on stressed-skin structures may be keptinformed regarding the work of the subcommittee, abrief summary of the tinutes of each meeting is pre-pared for circulation. These minutes record thesuggestions that are made from time to time regardingproblems suitable for research (in other than Govern-ment Iaborrdcn-ies).

The subcommittee is now preparing a chart showingthe present status of research on stied-skin struc-tures. Accompanying the chart will be a bibliographyand brief discussion of the most authoritative litera-ture on the various phases of the subject. .

Rae-arch on thin+od?ed cylino?ers.-Laet year theCommittee published a preliminary report on thestrength of thin-walled cylinders in torsion. This yeara more complete report on the same subject is beingpublished under the authorship of Dr. L. H. Donnellof the California Institute of Technology (TechnicalReport No. 479). In the recent report, all the availa-ble test data on thin-walled cylinders in torsion areincluded and the rikndts correlated with theory.

A report on the strength of thin-walled cylindemin compression is now in the process of publication(Technical Report No. 473). In this report all theavailable test data are included, together with theresults of teds made by the Commjttee and by theCalifornia Institute of Technology. The results ofthe tests are presented in nondimensional form anddiscussed in connection with existing theory.

A report on the strength of thin-walled cylindersin pure bending is also in process of publication(Teohnical Note No. 479). In this report no con-sideration is given to theory but the results are

COMWTPEU3 FOR AERONAUTICS

ptintcd in nondimensional form for compruison withthe results of similar tests in compression published inTechnical Report No. 473. The important conclusionregarding the strength of thin-walled cylindem inbend@ is that the stress on the extreme fiber atfailure as calculated by the ordinary theory of bendingis from 30 to 80 percent greater than the compressivestrength at failure for thin-walled cylindem of the mmedimensions.

A report on the strength of thin-walled cylinders ofcircular section subjeckd to combined transverse shearand bending is in progress. This report also coverswork which is largely experimental, but the resultsare presented in nondimensional form and comparedwith the results of torsion and bending tests previouslyreported. The tests show that, for large values of thoratio of moment to radius-shem (iU/rV), the cylinderfails in bending and the Btress on the extreme fiber atfailure, as calculated by the ordinary theory of bending,is equal to the stress on the extreme fiber at failurefor a cylinder of the same dimensions in pure bending.For small values of M/r’V, the cylinder fails in shearand the maximum shearing stress at failure as calcu-lated by the oridinary beam theory is approximatelyequal to the shearing stress at failure for a cylinder ofthe same dimensions in tomion (pure shear). Forintermediate values of M/rV, there is a transition fromfailure by bending to failure by shear that is accom-panied by a reduction in strength. In calculating thestingth of the cylinder, this reduction in strengthmay be allowed for by a proper consideration of thedispemion of the results of the tests on thk-walledcylinders in pure bending.. Strength tests on thin-walled truncated cones and

thin-walled cyli.ndem of elliptic section have beencompleted. The results of these tests will be publishedlater.

Rwm.rch on strengthof &i@ners.-After the airphmodivision of the Ford Motor Co. suspended operationslast yeru a large portion of the engineering dataaccumulated from its researches on various types ofstructural elements was made available to the com-mittee. As a portion of these data revealed thatvaluable information regarding local fsilure in stiffenerscould be obtained, it is now being condensed for issu-

ante in one or more reports. The reports a9 finallypublished will inchde design charts with the criticalstresses plotted against the proper dimensions of thestiffener sections.

R%eamh on strengthof eti~ened dcin.e.-lh collabora-tion with Professor NiIes of Stunford University, theCommitti is preparing for publication a general reportsummarizing all the teats made to date on the compres-sive strength of corrugated sheet. The data for use inthis report have been assembled from various sources,including the Army, the Navy, aircraft manufac-

REPORT NATIONAL ADVISORY

turers, and the Massachusetts Institute of Technology.In this report the strength of corrugated sheet for thevarious types of failure will be prssentid in chart formcorrelated with the column curve for the material.(Xmsideration will alao be given to the effect of pitch-line curvature on the strength of corrugated sheetand the effect of nonuniform spachg of transvemerings on the column strength of the corrugations.

During the past year the Committee published areport on the comp--ve strength of flat and slightlycurved sheet and stiffener combinations (Te@nicalNote No. 456). In this report the accuracy of threemethods based upon various assumptions for calcu-lating the compressive strength of flat sheet andstifFener combinations was compared. The methodbased upon mutual action of the stiifener and on effec-tive width of sheet as a column gave the beat agree-ment with the results of tests. The investigation ofthe effect of small curvature presented in the reportresulted in the conclusion that the cornpresaive strengthof curved panels is, for all practical purposes, equal tothe strength of flat panels except for thick sheet wherenonuniform curvature throughout the length of thepanel may crmse the strength of a curved panel to beas much as 10 to 15 percent less than the strength ofa cmmwponding flat panel.

De&gnof rings.-During the past year the Conmiitteepublished two reports on the stress analysis of rings(Technical Notea Nos. 444 and 462). By use of theformulas and chark presented in tbeae reports thedesigner is relieved of the necessity of making a leaat-work analysis when calculating the stresses in circularand elliptic rings for the majority of loading conditionsthat are likely to be imposed on the main frames of amonocoque fuselage. The study is being extended toan analysis of the forces that act upon the intermediaterings between the main rings of monocoque fuselages.

Design of be.anu king thin webs in diagonal &n-&.—During the past year a study was made and areport prepared (Technical Note No. 469) summarizingthe essential formulas for the dm”gn of diagonal ten-sion field beams; that is, beams with very thin webs,the theorg of which was developed by Professor Wag-ner of Germany. The purpose of this report was topresent in condensed form a brief summary of thefundamental principles and useful formulas for thespecific use of the designer.

COMMITTEE FOR AERONAUTICS

SUBCOMMITTEE ON METHODS

27

AND DEVICES FORTESTING AIRCRAFT MATERIALS AND STRUCTURES

The Committae has continued the work on the survey]f methods and devices for testing aircraft materialsmd structures, with a view to publication of thenaterial in a series of reports dealing with various?hases of the teding of aircraft materials and struc-hms. At the request of the Subcommittee on Air-mft Structures, priori~ is being ~“ven to a special~port on extensometera which is being prepared formblication.

SURCOmTTEE ON MISCELLANEOUS MATERIALS

Developed of jire-re+nktanidope for aircrafi.-The~vailable celhdose esters and synthetic r- wereinvestigated to aswertain their relative vahm inrendering dopes for airplane wing fabric nonfhrnmable.None of the resins studied gave satisfactory tautness.Cellulose acetate dope was found to be the mostsatisfactory fire-resistmt material of all the productsmzunined. Additional p@ection is obtained byimpregnating the fabric with an aqueous solution of aboric acid-borax mixture before applying the cellu-[ose acetate dope. Fabric fireproofed and doped inthis manner is not ignited by lighted matches, ciga-rettes, redhot nails, nor burning gaaoline. The amountof ii.reprooi@ salt mixture required on the cloth is ‘approximately 5 percent of the total weight of thedoped fabric.

REPORT OF COMMITTEE ON PROBLEMS ORAIR NAVIGATION

In response to the need for the coordination ofscientific research being conducted by a number ofdiflerent agencie9, both within and without theGovernment, on the problems of air navigation, theNational Advisory Committee for Aeronautics hasestablished a committee on problems of air naviga-tion, with membem representing the principal agenciesconcerned with the development of aids to air naviga-tion.

In order to cover effectively the large and variedfield of research and development on problems of airnavigation, the following subcommittees have ‘beenorganized under the committee on problems of airnavigation: subcommittee on instruments and sub-committee on meteorological problems.

PART II

ORGANIZATION AND GENERAL ACTMTIES

ORGANIZATION

The National Advisory Commiti%e for Aeronrmticsis composed of 15 members appointed by the Presidautand. serving as such without compensation. The lawprovides that the members shall include 2 representa-tives each from the War and Navy Departments and1 wwh from the Smithsonian Institution, the WeatherBureau, and the Bureau of Standards, together withnot more than 8 additional pemons “who shall beacquainted with the needs of aeronautical science,either civil or military, or skilled in aeronauticalengineering or iti allied sciences” One of these eightis rLrepresentative of the Aeronautics Branch of theDepartment of Commerce. Under the rules andregulations governing the work of the Committee asapproved by the President the chairman and vicechairman of the committee are elected annually.

On July 12, 1933, president Roosevelt appointedDr. Lyrmin J. Briggs a member of the committee tosucceed Dr. George K. Burgess, whose death on July 2,1932, had been noted in the preceding angual report.Dr. Briggs had succeeded Dr. Burgess as director of theBunmu of Standards, and his membership on the Com-mittee is as a representative of that Bureau.

The first vacancy occurring during the past year wascaused by the tragic death of Rear Admiral WilliamA. Moffett, United States Navy, Chief of the Bureau ofAeronautic-s, Navy Department, who was killed inthe destruction by storm of the airship Akron onApril 4, 1933. For 12 years he had served on thisCommittee faithfully and with great distinction. Hisoutstanding service as a member was his uniformsincerity in fostering truly cooperative efforts in orderto prevent duplication in the field of fundamentalresearch in aeronautics. His colleague adoptedresolutions mourning his loss and testifying to theenduring value of his great work for the developmentof aviation for national defense.

Rear Admiral Ernest J. King, United States Navy,succeeded Admiral Moffett as Chief of the Bureau ofAeronautics, and on July 19, 1933, he waa appointedby President Roosevelt to succeed Admiral Moffettas a member of this Committee.

A second vacancy during the year was caused bythe resignation on November 9, 1933, of Dr. WtiamF. Durand, who was one of the original membersappointed by President Whn in 1915. Dr. Durandhad sened as chairman of the Committee in 1916 and

28

1917. He resigned because his residence on the Pa-cific coast made it d.iflicult for him to attend meetingsfrequently, and was succeeded as a member of theCommittee by Mr. Eugene L. Vidal, Director ofAeronautics, Department of Commerce.

The executive office9 of the Committee, includingits offices of aeronautical intelligence and aeronauticalinventions are located in the Navy Building, Wash-ington, D. C., in cIose proximi~ to the air organim-tions of the Army and Navy.

The office of aeronautical intelligence was estab-lished in the early part of 1918 as cm integral branchof the Committee’s activities. It is the designateddepository for scientific and technical data on aero-nautics secured from all parts of the world. Thematerial is classhied, cataloged, and disseminated,

To assist in the collection of scientific and technicrddata, the Committee maintains a technical assistantin Europe with headquarter at the American Embassyin Paris.

~ONSIDERATION OF AERONAUTICAL INVENTIONS

In accordance with act of Congress approved July2, 1926, as amended by act approved March 3, 1927,the Committee passes upon the merits of aeronauticaluwentions and designs submitted to any branch of theGovernment and submits reports thereon to the Aero-nautical Patents and Design Board, consisting ofkiitant Secretaries of the Departments of War,Navy, and Commerce. That board is authorized,~pon the favorable recommendation of the Committeejto “determine whether the use of the design by theGovernment is desirable or necessary and evaluate thehsign and flx its worth to the United Statea in anmount not to exceed $75,000.”

The work of considering aeronautical inventionsmd designs submitted is under the supervMon of the>ommittee on aeronautical inventions and designs.

SUBCOMMI’ITEES

The executive committie has organized a number]f standing committees, with subcommittees, for thepurpose of supervkiig its work in their respectiveields. The four technical committees on aero-@mmics, power plant9 for aircraft, materials forircraft, and problems of air navigation, and theirmbcommittees supervise and direct the areonrmticalresearch conducted by the Advisory Committee andinordinate the investigations conducted by other~enciea. Their work has been described in part I.

RDPORT NATIONAL ADVISORY COMMITTEE FOE AERONAUTICS 29

The organization of the committees and subcom-mittees under the executive committee is w follows:

COMMITTEE ON AERODYNAMICS

Dr. David W. Taylor, chaiian.Dr. L. J. Bri~ Bureau of Standards.Tlwophile dePort, Mat4riel Division, ArmY Air Corps,

Wright Field.Lt. Comdr. W. S. Diehl (C.C.), United Statas Navy.Dr. H. L. Dryden, Bureau of Standards.Riahard C. Gazley, Aeronautic Branch, Department of

Cammerce.Maj. C. W. Howard, United Statea Army, Mat&iel Division,

Air Corps, Wright Field.George W. Lewis, National Advisory Commit& for Aero-

nautioa (ex offioio member).Dr. Charles F. Marvfn, Weather Bureau.Lt. Comdr. Donald Royce (C.C.), United StatM Navy.Hon. Edward P. Warner, editor of Avhtion.Dr. A. F. Zahm, Diviefon of Aeronautic, Library of Cengress.

8UECOhlMPlTEEON NRSHIpS

Hon. Edward P. Warner, editor of Aviation, &airman.Starr Truaoott, National Advieory Committee for Aero-

nautic, vice ohairman.Dr. Karl Arnctein, Goodyear-Zeppelin Corporation.Commander Garland Fulton (C.C.), United Stab Navy.Maj. Wiiam E. Kepner, United Statea Army, Mat&iel

Divieion, Air Caps, Wright Field.George W. Lawia, National Advisory Committee for Aero-

nautfca (es offloio member).Ralph H. Upson, Ann Arbor, Mioh.

COMMPITEE ON POWER PLANTS FOR AIRCRAFT

Hon. Wflliam P. MaoCraoken, Jr., chairman.George W. Lewie, National Advieory Committee for Aero-

nautic, vice ohairnmn.Henry M. Gmne, Society of ‘Automotive Engineem. ‘‘Prof. Harvey N. Davic, Stevens Institute of Technology.Dr. H. C. Diokinaon, Bureau of Standards.Carlton Kemper, National Advieory Cmmnittee for Aero-

nautka.Lt. Comdr. F. M. Maile, United States Navy.Lt. E. M. Powem, United States Army, MatMel DivMon,

Air Corps, Wright” Field.Prof. C. Fayette Taylor, Macaaohueeti Institute of Tech-

nology.

COMMI’JWEE ON MATERIALS FOR AIRCRAIW

Dr. L. J. Brfgge, Bureau of Standards, ohairman.Prof. H. L. Whittemore, Bureau of Standards, vice chairman

and aoting secretary.S. K. Colby, Alum”num Co. of America.Lt. Alden R. Crawford, United States Army, Mat&iel Divi-

sion, Air Corps, Wrfght I%ld.Lt. N. A. Draim (C.C.), United StatM Navy.Warren E. Emley, Bureau of Standardc.Commander Garland Fulton .(C.C.), United Statea Navy.Dr. H. W. Gfllett, Battclle Memorial Inetitute.C. H. Helms, National Advkory Committee for Aeronautic-s.Dr. Zay Jefferiea, American Magnesium Corporation.J. B. Johnson, Mat&fel Divieion, Army Air, Corps, Wright

Field.George W. Lewis, National Advisory Committee for Aero-

nautic (ex officio member).H. S. Rawdon, Bureau of Standards.

E. C. Smith, Republio Steel Corporation.G. W. Tmyer, Forest Produota Laboratory.Starr Truscott, National Advisory CQmmittee for Aeronautic.Hon. Edward P. Warner, editor of Aviation.

SUECOM~13E ON M~AL9

H. S. R.mvdon, Bureau of Standarc@ chairman.Dr. H. W. Gillet$ Battelle Memorial Institute.Dr. Zay Jefferies, Amerioan Magnecium Corporation.J. B. Johnson, Mat&iel Divieion, Army Air Caps, Wright

Field.George W. Lmvie, National Advicory Committee for Aero-

nautics (ex officio member).E. C. Smith, Republio Steel Corporation.Starr Truacott, National Advisory Committee for Aero-

nauticalProf. H. L. Whittcmorc, Bureau of Standards.

SUECO~ES ON ~CIMPl! STRUGPIJRES

Starr Tmaoott, National Advieory Committes for Aero-nautics, chairman. .

Capt. Howard Z. Bogert, United States Army, Mat&ielDivision, Air Corps, Wright Field.

C. P. Burgess, Bureau of Aeronautics, Navy Department.Richard C. Gazley, Aeronautics Branoh, Department of

CommercaCharle.kWard Hall, Hall-Aluminum Airoraft Corporation.Lt. Lloyd Harrison (C.C.), United States Navy, Naval Air-

oraft Faotory.George W. Lem”ej National Advicory Committee for Aero-

nautic (CX050io member).Lt. Comdr. 1% D. MaoCart (C.C.), United Stak Navy.Charl- J. MoCarthy, Chance Vought Corporation.Prof. J. S. Newell, MasaachwAta Institute of Tcohnology.J. A. lloch~ Mat&icl Divicfon, Army Air Corpg Wrfght

Field.Dr. L. B. Tuokcrman, Bureau of Standards.

TEMPOItARY SUECOMMITTEE ON RESEARCH PROGEAM ONMONOCOQUE Dli!31GN

George W’. Lmvia, National Advicory Committee for Aero-nautics, chairman.

Capt. Howard Z. Bogert, United Statee Army, Mat&ielDivision, Air Corps, Wright Field.

Riohard C. Gazley, AeronautIce Branch, Department ofCommerce.

Eugene E. Lundauiat, National Advisory Cknnrnittee forAeronautic.

Lt. Comdr. R. D. MacCart (C.C.), United Statea Navy.Dr. L. B. Tuckerman, Bureau of Standards.

SUSCOMMIITEE ON METHODS AND DEVICIH FOE TE9TINGAIRCEAIW MATESIA19 AND STRU~

Henry J. E. Reid, National Advicory Committea for Aero-nautic, chairman.

Capt. Howard Z. Bogert, Unftad Statea Army, Mat&ielDivieion, Air Corps, Wright Field. WPM:

Lt. Lloyd Harrison ~C.C.), United States Navy, NavalAircraft Factory.

George W. Lewis, National Advisory Committee for Aero-nautic (ex officio member). ha

Eugene E. Lundqukt, National Advicory Committee forAeronautic-c.

FL L. Templin, Alundrmrn Co. of AmericaG. W. Trayer, Fored Products Laboratory.Dr. L. B. Tuckerman, Bureau of Standards.

.. -. .. —...- -. .. —------ —--—— - ---- —-——

30 REPORT NATIONAL ADVISORY COMMITTEH FO13 A13RONAUTICS

SUBCOMMITIZE ON M13CEZLANEOlJS MATERINS

C. H. Hehns, National Advisory Committee for Aeronautic,Ohairman.

Dr. W. Blum, hreau of Standards-. J. Cleary, Mat&iel Division, Army Air Corps, Wright

Held.Warren E. Emley, Bureau of Standards.George W. I%wia, National Advisory Commit&c for Aero-

nautics (ex officio member).J. E. Suliivan, Bureau of Aeronautics, Navy Department.G. W. Trayer, Forest Products Laboratory.P. H. Walker, Bureau of Standards.G. P. Young, Mat6riel Division, Army Air CQrps, Wright

Field.

COMMITTEE ON PROBLEMS OF AIR NAVIGA~ONHon. Wiiam P. McCracken, Jr., chairman.Dr. L. J. Briggs, Bureau of Standards.Lloyd IUpenschied, American Telephone and Telegraph Co.Maj. Gcn. B. D. Fouloia, United States Army, Air COWS,

War Department.Paul Henderson, National Air Transport, Ino.Capt. S. C. Hoopx, United States Navy.. Dmtor of Naval

Communications, Navy Department.Dr. J. C. Hunaaker, Mamachumtts Institute of Technology.George W. Iavia, National Advisory Gnnmittee for Aero-

nautics (es officio member).COL Charles A. Lindbergh.Res Martii, Aeronautics Branch, Department of Commerce.Dr. Charles F. Marvin, Weather Bureau.Lt. J. P. W. Vest, United Statea Navy, HYdrograPbic Office,

Navy Department.Eugene L. Vi@ Director of Aercmautica, Department of

commerce.Charlea J. Young, R.C.A. Victor Co., Inc.

smlCOM?dl’lTEE ONINSTEUbiENTSDr. L. J. Briggs, Bureau of Standards, chairmamMarshall S. Bogga, Aeronautic Branch, Department of

Commerce.Dr. W. G. Brombacher, Bureau of Standards.C. FL Colvin, %ciety of Automotive Engineem.Capt. A. F. Hegonberger, United States Army, Mat&iel

Division, Air Carps, Wright Ilteld.Dr. A. W. Hull, Generai Electrio Co.Carl W. Ketie~ Kouffcl and 12swr. -George W. Lsvis, National Advisory Cknnmitteo for Aero-

nautics (ex offioio member).Lt. C. D. McAllister, United Statea Army, Mat&iel Division,

&r Cap, Wright Field.Henry J. E. Ibid, National Advisory Canmittee for Aero-

nautic.Lt. L. D. Webb, United States Navy.Charlea J. Youug, RCA. Victor Co., Inc.

SUBCOMMITTEE ON METEOROLOGICAL PFcOBLEBL9

Dr. Charles F. Marvin, Weather Bureau, ohairman.W. lL Gregg, Weather Bureau.Dr. W. J. Humphreys, Weather Bureau. .Dr. J. C. Hunaaker, Mmsachusetta Irhtute of Technology.George W. IXvis, National Advisory Committee for Aero-

nautics (os orncio member).Lt. F. W. Mlchelderfer, United Statea Navy, Navai Air Sta-

tion, Lakehurst.Dr. C. G. Rossby, M~husetts Institute of Technology.Eugene Sibley, Aeronautics Branch, Department of Com-

merce.. Capt. Alfred H. Thiessen, United States ArmY, SZ mI’PS,

War Deparhnent.

COMMf!lW3E ON AIRCRAFT ACCIDENTS

Hon. Edward P. Warner, editor of Aviation, ohairman.George W. Lefi National Advisory Committee for Aero-

nautics.W. Fiske Marahall, Aeronautics Branoh, Department of

commerce.Lt. Comdr. A. C. McFaLl, United States Navy.Lt. Samuel P. Mills, United States Army, Air Corps, War

Department.Capt. Max F. Schneider, United State.SArmy, ~ COIYJS,

Wm Department.Lt. H. B. Temple, United StateaNavy.

COMMIT1’EE ON AERONAUTICAL INVENTIONS ANDDESIGNS

Dr. David W. Taylor, chairman.Capt. Arthur B. Cook, United Statee Navy.Dr. CharleaF. Marvin, Weather Bureau.Brig- Gen. Henry C. Pratt, United States Army, Mat6riel

Division, Air Corps, Wright Field.John F. VIOtOry,seore~.’

CO~EE ON PUBLICATIONS AND INTELLIGENCE

Dr. Joseph S. @es, chairman.Dr. CharleaF. Marvin, Weather Bureau, vice ohairnmn.Mfss M. M. Muller, secretary.

COMMTl!’1’EE ON p~so~~, B~D~GS, ANDEQUIPMENT

Dr. Joseph S. Amw, ohrdrman.Dr. David W. Taylor, vice chahman.J&n F. VICtOry,secretary’.

LANGLEY MEMORL4L AERONAUTICAL LABORATORY

The Committee’s laboratory is located on the Armyflying field, known as “Langley Field, Vn.”, on groundset aside by the War Depa@nent for the Committeo’suse. The laboratoW is subject to the military police,fire, and sanitary regulations governing the post, butis otherwise under the exclusivo and direct control ofthe Committee. The Committee’s research work isconducted without interference with military opera-tions at the field, and there is a splendid spirit ofcooperation which has materially aided the Committeein its work.

As many of the Committee’s”fundmenti researchesare based upon requests received from the Army andNavy for the investigations of particular problems,there has been full cooperation on the part of theA-my and Navy in placing at the Committee’s disposalairplanas, engimw, rmd ac~ofi~ needed for researchpurposes.

The Committee’s laboratories comprise 11 buildingsand a paid research stdf of 260 employees.

ANALYSIS OF ATRCR~ ACCIDENTS

A standard procedure for the analysis of aircraftaccidents proposed by the committee on aircraftaccidents, approved by the executive committee, andpublished as Technieal Report No. 357, is followod bythe War, Navy, and Commerce Dep~tmen~. Uni-formity in interpretation of the Committee’s plnn is

REPORT NATIONAL ADVISORY

secured through meetings of the committee on air-craft accidents, which includes in its membershiprepresentatives of the War, Navy, and Commerce airorganimtions. The result is to render accidentstatistics comparable and thus through the accuratedetermination of the causes of accidents to be enabledto take appropriate measures for the reduction ofaccidents due to such causes.

TECHNICAL PUBLICATIONS OF THE CO~~Tl?EE

The Committee has four series of publications,namely, technical reports, technical notes, technicalmemorandums, and aircraft circulars.

The tachnical reports present the results of funda-mental research in aeronautics. The technical notesare mimeographed and present the results of shortresearch investigations and the results of studk ofspecific detail problems which form parts of longinvedigations. The technical memorandums aremimeographed and contain trrm.shtions of importantforeign aeronautical articles. The aircraft circularsare mimeographed rmd contain descriptions of newtypes of foreign aircraft.

The following are lists of the publications &ued:

LIST OF TECHNICAL REPORTS lSSUED DURING THEPAST YEAR

No.441. A Flight Investigation of the Spinning of the NY-I Air-

plane with Varied Masa Distribution and Other kfodi-fieations,and an AnalYsis13asedon Wind-Tunnel T*.By Nathan F. Soudder, National Advisory Committeefor Aeronautic.

442. A Comparison between the Theoretical and MeaauredLongitudinal Stability Cbamoteriaties of an Airplane.By Hartley A. Sou16and John B. Wheatley, NationalAdvisory Committee for Aeronautics.

443. Preaeure-Distribution Memurementi on the Hull andFins of a l/40-Scale Model of the U.S. Airship Akron.By Hugh B. Freeman, National Advisory Committeefor Aeronautics.

444. Wnd-Tumd Research Comparing Lateral Control De-vices, Particularly at High Angles of Attack. VI—Skewed Ailerons on Rectangular Wings. By Fred E.Weick and Thomas A. Harris, National Advisory Com-mittee for Aeronautics.

446. Working Charte for the Determination of the Lift Dk-tribution between Biplane Wings. By Paul Kuhn,National Advisory Commitke for Aeronautic.

446. Airfoil Seotion Charaoteristka u Affected by Protuber-ances. By Eastman N. Jacobs, National AdvisoryCommittee’ for Aeronautics.

447. Statio Thrust of Airplane Propellem. BY Walter S. Diehl,Bureau of Aeronautka, Navy Department.

448. Improved Apparatus for the Measurement of Fluotua-tiona of Air Speed in Turbulent Flow. By W. C. Meek,Jr., and H. L. Dryden, Bureau of Standards.

449. Wing CharacWtiea aa Affeot%d by Protuberances ofShort Span. By Eastman N. Jaoobs and Albert Sher-man, National Advisory Cornrnittea for Aeronautic-s.

460. The Calculation of Take-Off Run. By Walter S. Diehl,Bureau of Aeronautics, Navy Depatment.

461. The Drag of Two Streamline Bodies as MTeokd by Pro-tuberances and Appendagea. By Ira H. Abbott,National Advisory Commitke for Aeronautics.

COMMITTED FOR AERONAUTICS

I No.452. General Potential Theory. of

31

Arbitrarywing sections.By T. Theodomen and I. E. Garriok, National AdvisoryCommittee for Aeronautiea.

453. The Estimation of Masimum Load Capacity of &.aplanesand Flying Boats. By Walter S. Diehl, Bureau ofAeronautics, Navy Department.

454. Photomicrographio Studies of Fuel Sprays. By Dana W.Lee and Robsrt C. Spencer, National Advisory Com-mittee for Aeronautiea.

455. Penetration and Duration of Fuel SDravsfrom a PurnD,Injeotion System. By A. M. Rothr&k-&d E. T. Mars~,National Advisory Commit&s for Aeronautics.

456. The Aerodynamic Forces and Momenta Exerted on aSpinning Model of the NY-1 Airplane as Measured bythe Spinning Balance. By M. J. Bamber and C. H.Zimmerman> National Advisory Committee for Aero-nautics.

457. Maneuverability Invmtigation of an 03 U-I ObservationA~lane. By F. L. Thompson and H. W. Kirsohbaum,National Advisory Committee for Aeronautics.

468. Relative Iaading on Biplane Wings. By Walter S. Diehl,Bureau of Aeronautics, Navy Department.

“*9. The N.A.C.A. Full-scale Wind TurmeL By Smith J.DeFran~ National Advisory Committee for Aero-nautics.

460. The Characteristic of 78 Related Airfoil Seotiona fromTests in the Variable-Density Wind TunneL By Eaat-man N. Jacobs, Kenneth E. ward, and Robert M.Pinkerton, National Advisory Cornxrdtteefor Aero-nautics.

461. Interference on an Airfoil of Finite Span in an OpenRectangular Wind Tunnel. By Theodore Theodorsen,National Advisory Committee for Aeronautic.

462. Tests of Nacelle-Propeller Combinations in Various Posi-tions with Reforenee to Wings. III-Clark Y Wmg-Varioua Radial-Engine Cowlings-Tractor Propeller.By Donald H. Wood, National Advisory Commit@efor Aeronautics.

463. The N. A.C.A. High-Speed Wind Tunnel and Teds of SixPropsller Seotions. By John Staok, National AdvisoryCommit& for Aeronautics.

464. Negative Thrust and Torque Characteristiea of an Ad-justable-Pituh Metal Propeller. By Edwin P. Hartman,National Advisory Cornmitke for Aeronautics.

46fi. Determination of the Theoretical Presure Distributionfor Twenty Airfoils. By I. E. Garrick, NationalAdvisory Comrnit&e for Aeronautics.

466. Airoraft Power-Plant Instruments. By Harcourt Sontagand W. G. Brombaoher, Bureau of Standards.

467. The Experimental Determination of the Moments ofInertia of Airplanes. By Hartley A. Sou16 and Marvel “P. Miller, National Advisory Committee for Aeronau-tics.

468. The Interference between Struts in Varioua Combiia-tiona. By David Bkraarm and William H. Herrn-steii, Jr., National Advisory Committee for Aeronautics.

469. Inoreasing the Air Charge and Scavenging the ClearanceVolume of a Compdon-Ignition Engine. By J. A.Spanogle, C. W. Hioka, and H. H. Foster, NationalAdvisory Commitke for Aeronautic.

470. The N.A. C A. Tank. A High-Speed Towing Basin forTeding Models of Seaplane Floats. By Starr TruaeobNational Advisory Commit&e for Aeronautics.

471. Performance of a Fuel-Injection Spark-Ignition EngineUsing a Hydrogenated Safety FueL By Oscar W.Schey and Alfred W. Young, National Advisory Com-mittee for Aeronautics.

32 REPORT NATIONAL ADVISORY

No.472. Wind-Tunnel Teats on, combinations of a Wing with

Fixed Audiary Airfoils Having Various Chords andPromea. By Fred E. Weick and Robert Sanders,National Advisory Committee for Aeronautic.

473. Strength Testa of Thin-Walled Dumlumin Cylinders inCOmpredon. By Eugene E. Lundquiat, NationalAdvisory Committee for Aeronautics.

474. Nomenclature for Aeronautic. By National AdvisoryCommittee for Aeronautic.

LIST OF TECHNICAL NOTES ISSUED DURING THEPAST YEAR

4~2. Drag Teats of 4/9-Scale Model Engine Nacelks withVariow Cmvlings. By Ray Wider, National AdvisoryCommittee for Aeronautic.

433. The Pressure Distribution Over a Standard and a ModifiedNavy Elliptical Wiig TIP on a Biplane ixi Flight. ByRiohard V. Rhodq National Advisory Caurnittee forAeronautics.

434. Inftuence of Several Faotom on Ignition Lag in a Com-prwsion-Ignition Engine. By Harold C. Gerrish andFred Voss, National Advisory Cknrnit&m for Aero-nautics.

436. The Effect of CIeamnce Distribution on the Performanceof a Comprcwion-Ignition Engine with a PrecombtilonChamber. By C. S. Moore and J. H. Cdl@ Jr.,National Advisory Committee for Aeronautics.

436. The Effect of Connecting-Pasaage Dmeter on the Per-formance of a Compression-Ignition Engine with aPrecombustion Chamber. By C. S. Moore and J. H.Cd@ Jr., National Advisory Committee for Aero-nautics.

437. The Prwmre Distribution Over a Long Elliptical Wing Tipon a Biplane in Flfght. By Hiohard V. Rhode NationalAdvisory Committee for Aeronautic

43s. The Grseous Esplosive Reaotion at Constant Premme—Further Data on the Effect of Inert Gaaes. By F. W.St.eve~ Bureau of Standards.

439. hfeteorological Conditiona During the Formation of Iceon Airoraft. By L. T- Samuelp, Weather Bureau.

440. Flight Teak to Determine the Effect of a Fised AuxiliaryAirfoil on the Lift and Drag of a Parasol Monoplane.By Hartley A. Soule, National Advisory Commit& forAeronautic.

441. Rolling, Yawing, and Hinge Moments Produced by Rec-tangular Ailerons (Correlating Technical Reports Nos.298, 343, and 370). By IL H. Heald, hmau ofstandard%

442. Jet Propulsion with Special Reference ti Thrust Aug-menters. By G. B. Schubauer, Bureau of Standards.

443. Wiid-Tunnel Research Comparing Lateral ControlDevices, Particularly at High Angles of Attack.Part VII-Handley Page Tip and Full-span Slots m-thAilerons and Spoilers. By Fred E. Weiek and Carl J.Wenzinger, National Advisory Committee for Aero-nautic.

444. Working Charts for the S& Analysis of Efliptio Rings.By Walter F. Burk~ University of Miohigan.

445. Wiid-Tunnel Reaearoh Comparing Lateral Control De-vic~ Particdarly at High An@ of Attaok. PartVIH-Straight and Skewed Ailerons on Wings withRounded Tips. By Fred E. Weiok and Joseph A.Shortal, National Advisory Committee for Aero-nautics.

446. Estiition of the Variation of Thrust Horsepower withAir Speed. By Shatswell Ober, Maamohu&ta Insti-tute of Technology.

CO~E FOR AERONAUTICS

No.447. The Effeot on Lift, Drag, and Spinning Characterfstios of

Sharp Leading Edges on Airplane Wings. By Fred E.Weiok and Nathan F. Scudder, National AdvisoryCommittee for Aeronautioa.

448. Effeot of Aileron Displacement on Wing Chamcterisths.By IL H. Heald, Bureau of Standards.

449. lt’ind-Tunnel Researoh Comparing Lateral control De-vices, Particularly at High Angles of Attaok. PartIX—Tapered Wings with Ordinary Ailerons. ByFred E. Weiok and Carl J. Wenzinger, National AdvfaoryCommittee for Aeronautics.

450. Mercerization of Cotton for Strength with Special Refor-enoe to Aircraft Cloth. By J. B. Wilkic, Bureau ofStandards.

451. Wind-Tunnel Ikearoh Comparing Lateml tintrolDevica, Particularly at High Angles of Attaok. PartX—Various Control Devices on a Wing with a Fi..odAuxiliary Airfoil. By Fred E. Weick and Riohard W.Noym, National Advisory Commit& for Aeronautics.

452. The Importance of Auto-Ignition Lag in Knooking. ByE. S. Taylor, Mmaachuaetts Intiltute of Technology.

463. Experiments with a Counter-Propeller. By E. P. L.ealey,Stanford University.

454. The N.A.C.A. Combusfon Chamber Gas-Sampling Valveand Some preliminary Test Results. By J. A. Spanogleand E. C. Buckley, National Advfsory Commfttee forAeronautioa.

456. Comparison of Three Methods for Calculating the Com-ptive Strength of FJat and Slightly Curved Sheet andStiffener Combinations. By Eugene E. Lundquid,National Advisory committee for Aeronautics.

466. The Aerodynamic Effect of a Retmotable Landing Gear.By Smith J. DeFmnce, National Advfsory Committeefor Aeronautic.

457. The Aerodynamic Chamcteristics of Airfoils as Affeotedby Surface Roughrme. By Ray W. Hooker, NationalAdvisory Comnittm for Aeronautics.

458. Wind-Tunnel Research Comparing Lataral Control De-vices, Patilcularly at High Angles of Attaok. Part XI—Various Floating Tip Ailerons on Both Rootangular andTapered Wings. By Fred E. Weiok and Thomas A.Hmria, National Advkory Commitke for Aeronautics.

459. Wind-Tunnel Tests on Model Wiig with Fowler Flap andSpecially Developed Leadfng-Edge Slot. By Fred E.Weiok and Robert C. Platt, National Advisory Com-mittee for Aeronautic.

460. Full-Scale Wind-Tunnel Research on Tail Buffeting andWing-Fuselage Interference of a Lmv-Wing Monoplane.By Manley J. Hood and James A. White, NationalAdvisory Committee for Aeronautic.

461. The Effect of Rivet Heads on the Characteristics of a6- by 36-Foot Clark Y Metal Airfoil. By Clinton H.Dearborn, National Advisory Committee for Aero-nautics.

462. Formulas for the Strws Analysis of Ciroular Rings in aMonocoque Fuselage. By Roy A. Miller, Con-solidated Airomft Corporation, and Karl D. Wood,Cornell University.

463. Aerodynamic Teataof a Low Aspeot Ratio Tapered wingwith Various Flaps, for Use on Tailless Airplanes. ByFred E. Weick and Robert Sanders,National AdvisoryCommittee for Aeronautics.

464 A Completi Tank Test of a Model of a Flyfng-Boat Hull—N.A.C.A. Model No. 11. By James M. ShoemakorandJohn B. Parkinson, National Advisory Cwnrnittce forAeronautic.

REPORT NATIONAL A.IMTSORY COMMI?XEE FOR AERONAUTICS 33

No.466. Some Chamaterietice of Spmys Obtained from Pinth+

Type Injeotion NozzlM. By E. T. Marah and C. D.Waldron, NationalAdvisory Commitke for Aeronautics.

466. Engine Performance with a Hydrogenated Safety Fuel.By Osmr W. Sohey and Alfred W. Young, NationalAdvkory committee for Aeronautic.

467. Shnplflied Aerodyrmnio Analyaie of the Cyologiro Ro-tdiig-wiig System. By John B. Whedleyj NationalAdvisory committee for Aeronautic.

468. A Study of Factora Affeoting the Steady Spin of an Air-plane. By Nathan F. Scudder, Natfonal AdvisoryCommittee for Aeronautics.

469. A Surnmary of Design Forxmdaa for Beama Having ThinWebs in Diagonal Tension. By Paul Kuhn, NationalAdvieory Cornmit~ for Aeronautioa.

470. A Complete Tank Teat of a Model of a Flying-Boat Hull—N.A.C.A. Model No. 11-A. By John B. ParMneon,National Advisory Committee for Aeronautic.

471. A Complete Tank Test o{ a Model of a Flying-Boat HuU—N.A.C.A. Model No. 16. By Jamea M. Shoemaker,National Advfsory Cotittee for Aeronautioa. .

472, The Effeot of Partfal-SpanSplit Flaps on the AerodynamicCharacteriatica6f a Clark Y Wing. By Carl J. Wen-zinger, National Advisory C+mnrnitteefor Aeronautic.

LIST OF TECHNICAL MEMOIMNDUMS ISSUED DURINGTHE PAST YEAR

No.687. Methode for Facilitating the Bhnd Landing of Airplamm.

By M. Heinrich Gloeckner. From !&itmhrift ftirFlugteohnik und Motorluftachi$fahrt, June 2+ 1932.

688. Speed and Premure Recording in Three-Dimensional Flow.By Dr. F. Krkam. From Zeitsahrift f6r Fh@echnikund Motorluftschiffahrt, July l% 1932.

689. The Problem of Tire Sizes for Airplane Wheels. ByFranz Miohael. From Zeiteohrift ftir Flugteohnik undMotorlufteohiffahrt, July 14, 1932.

690. Tmnatilon of Heat from a Flat Plate to a Fluid Flowingat a High Velocity. By Luigi Crocco. From L’Aerwtecrd~ February 1932.

691. Some Idesa on Wing Seaplanea. By Giovanni Pegna.From Riviata Aeronauti~ June 1932.

692. Methoda of Recording Rapid Wind Changes. By A.Magnan. From JahrbuchNo. 4 (1929) da Forsohunga-Inetituteader Rh5n-RmsMen-Gesellaohaft.

693. The Testing of Airplane Fabrica. By Karl Schmivogel.From Zeitxchrift filr Flugtechnik und Motorluftaohif-fahrt, Au@ 27 and September 14, 1932.

694. Combustion of Gaaeous Mixtures. By IL Duohene.From Publication Scientifiqueaet Teohniqueadu Min-iateredeI’Air, No. 11,ServicedesB.echeroheadel’A6ron-rbutique.

695. Automatia Stabili@ of Afrplanes. By Fr. Haua. FromL’A6ronautfque, May, June, July, and Au@ 1932.

696. The Problem of the Propeller in Yaw with Special Ref-erence to Airplane Stability. By Franz Miaztal-From Abhandlungen aua dem Aerodynamiachen In-stitut an der TeohniachenHocbachule Aachen, No. 11,1932.

697. The D.V.L. Gliding-Angle Control (W. Htibner Design).By Walter Htlbner and Wilhelm Pleines. FromZeitscMt ftlr l?lugteoludk und MotorluftsohMahrt,August 12, 1932.

698. DynarrduBreaking Tests of Airplane Parta. By HeinrichHertel. From Zeitaohrift f6r Flugtechnik und Motor-luftschfffahrt,August 14 and August 28, 1931.

No.699. The Procwa of Separation in the Turbulent Friotion

. Layer. By E. Gruschwitz. From Zeitaohrift fiirFlugtechnik und MotorluftschitTahr~ June l% 1932.

700. Inoreaaing the Vohunetrio Efficiency of Diesel Engin~ byIntake Pipex. By Hans List. From Mitteilungen ausden teohniachen Inatituten der StaaWohen Tung-ChiUniversitat, Ibport No. 4, April 1932.

701. The Effeet of a Gap between Elevator and Stabilizer onthe Statio Stability and Maneuverabfity about theLateral Axis in Flight. By Walter Hilbner. FromZWacbrift fUr Flugteobrdk und Motorluftsohiffahrt,June 14, 1932.

702. Determina tion of Inherent S~ by Measuring Defor-mation of DriRed Holes. By Josef Mathar. FromArchiv ftlr daa EMnhuttenwe8en (Communicationfrom the Aachen Aerodynarnio Institute), 1932-33.

703. Take-Off and Propeller Thrust. By Martin Sohrenk.From ZAsohrift fti. Flugtechnik und Motorluftaohif-fahrt, November 14, 1932.

704. Scale Effect of Model in Seaphm+l?loat Investigations.By W. Sottorf. From zeitschrift fiir Flugtechnik undMotorluftschMahrt, December 28, 1932.

705. The Critical Shear Load of Rectangular Platea. By EdgarSeydel. From Zeitaohrift f6r Flugteohnik und Motor-luftaohiffahrt, February 14, 1933.

706. Knowledge Gained from Pmotiod Experience in theDesigning of Airomft Engin~. By Oakar Kurtz.From Zeitsohrift filr Fh@eohnik und Mot@uftsohif-fahrt, December 14 and December 28, 1932.

707. Experiment-s with Needle Bearingc. By Periole Ferretti.From Rivista Aeronautioa, October 1932.

708. Flight-Test Data on the Static Fore-and-Aft Stability ofVariouc German Airplanm. By Walter Htibner. From!&tsohrift fiir Flugtechnik und Motorluftachiffahrt,January 28, 1933.

709. Future Problems of %aring Flight (Report of 1932 RhtinSoaring Conte3t). By Walter Georgii; and SyaternaticObservations of Local Cumuli. By Roland Eiaenlohr.From Zeitscbrift fiir Flugtecbnik und Motorluftsohif-fat@ March l% 1933.

710. Teate for the Elimination of Tafl Flutter. By CurtBiechteler. From Zeitachrift ftir Flugtechnik undMotorluftsch.itfahrt, January 14, 1933.

711. PIWWure Mae, Gae Vibmtiona, and Combustion NoisesDuring the Explosion of Fuels. By Profewor ‘iVawrz-iniok. From Automobiltichniache Zeitachrif~ February10 and Maroh 10, 1933.

712. The Schneider Trophy Contest. By Alfred RichardWeyl. From Zeitschrift fOr Flugteohnik und Motor-luftaohiffahrt, Auguet 12 and August 27, 1932.

713. Behavior of Vortex Syatema. By A. Betz. FromZeitaclmift fiir angwvandte Mathematik und Mecbanik,June 1932

714. A Simple Method for Inoreasing the Lift of AirplaneWmga by Means of Flaps. By Eugen Gruachwitz andO&ar Sohrerdt. From Zeitscbrift ftlr Flugteobnik undMotorluftschiffahrt, Ootober 28, 1932.

716. Preacure and Frictional -Rematance of a Cylinder at Rey-nolds Numbers 5,000 to 40,000. By L. Sohiller and W.Linke. From zeitschrift ftir Flugtecbnik und Motor-luftsoMffal@ April 13, 1933.

716. Development of the Rulec Governing the Strength ofAlrplan~. By H. G. Ktiaaner and Karl Thalau.Part I—German Loading Conditions Up to 1926.From Luftfahrtforacbung, June 21, 1932.

34 REPORT NATIONAL ADVISORY COMMXITEE FOR AERONAUTICS

~1~. Development of the Rules Govemlng the Strength ofAirplanEs By H. G. Kficsner and Karl Thalau. PartH—Loading Conditions in Germany (Continued); Eng-land, and the United States. From Luftfahrtforaohung,June 21, 1932.

718. Development of the Rnl= Goverrdng the S&ngth of Air-planes. By H. G. Ktkmmr and Karl Thalau. Part111-Imding Conditiona in Francq Italy, Holland, andRuaek-Aims at Standardization. From Luftfahrt-forsohnng, June 21, 1932.

719. Dimensfona of Twin Seaplane Floata. By L. Meyer.From Association Technique Maritime et Aeronautiqu~May 1933.

720. Reoent Ib=ults of Turbulence Research. By L. Praidti.From %itschrift dea Vereinea Deutacher Ingenie~February ~ 1933.

721. Rem& of Extended T&a of the Focke-Wulf 1? 19a“ Ente”, a Tail-Fii Airplane. By WaN.er Httbner.From Zeitsohrift. fikr Flugtedmik und Motorlufhohif-fahr$ April 28 and May 13, 1933.

722. Guide Vanea for Deflecting Fluid Currents with SmallLow of Energy. By G. Kr5ber. From Ingenieur-ArChiV, 1932.

723. An Airfoil Spanning an Open Jet. By J. Stfiper. FromIngenieur-Archiv, 1932.

LIST OF AIRCRAFT CIRCULARS ISSUED DURING THEPAST YEAR

172. The Mememohmidt M. 29 Touring Airplane (@mnEuI).A Two-seat Cantilever Monoplane. From informationfurnished by the manufacturers, and from %itschrift fitrFlugtechnik und Motorl@ohiffahrt, October 14, 1932.

173. NleuporLDelage 590 Military Airplane (Frenoh). ATwo-Place High-Wiig Cantilever Monoplaw FromRevue de la Soci6t4 G&n&ale A6ronautiqu~ October1932.

174. The D.H. “Dragon Moth” Commerofal Airplane (Ih-itieh).A Twin-Engine Si-Pascenger Biplane. From TheAeroplan~ December 21, 1932; and Flight December 22,1932.

175. Heinkel He 640 Sport Airplane (German). A Two-SeatLow-Wing Cantilever Monoplane. From data fur-nished by the manufacture.

176. The Caudron P.V. 200 Tonring Airplane (French). AnAll-Metal Amphibii Monoplane. From L’A&onau-tique, December 1932, January 1933; and from infor-mation furnished by the manufacturers.

177. The Bonlton and Paul P. 64 Maif-Carrier. A Two-Engine All-Metal Biplane. From The Aeroplane,April 5, 1933.

178. The Aimpeed “Courier” Commercial Airplane (Britii).A Low-Wing Cantilever Monoplane. From The Aero-phlrl~ March 22, 1933.

179. The Wedland “Wallace” General-Purpcm Airplane(IMtiih). An All-Metal Biplane. From Flight, May4, 1933.

180. The Dewoitfne D. 500 Pursuit Airplane (Frenoh). AnAU-Metal Cantilever Low-Wing Monoplane. Fromdata furniehed by the manufacturers.

1S1. The Shaokleton-Mnrray SM-1 Light Airplane. A TwoPlace High-Wing Monoplane. From The Aeroplane,May 17, 1933.

182. The Hanriot-Biche 110 Cl Airplane (Frenoh). An AU-Metal Low-Wing Pm@t Monoplane. By ReneRabion. From k A@ March 30, 1933; and L’A6ro-nautique, May 1933.

No.183. Heinkel He 70 Commemial Airplane (German). A

Seven-Seat Cantilever Low-Wing Monoplane. Fromdata furnished by the manufacturers; and Luftwaoht,March 1933.

FINANCIAL REPORT

The general appropriation for the National AdvisoryCommittae for Aeronautics for the iiscal year 1933, ascarried in the Independent Offices Appropriation Aotapproved June 30, 1932, was $900,000. In mcord-ance with provisions of the Economy Acte affectingpersonal services, furlough and compensation deduc-tions amounting to $72,58t3 were made during thefiscal year. The amount expended and obligated was$827,186, itemized as follows:

Personalwtic~--------------- j------------- $600,043.86SuppliMand -tils ------------------------ 38,309.12Cannmnioation s-M----------------------- 1,877.83Travel q~------------------------------ 10,256.30Transportation of tti~---------------------- 1, S46. 12

. .Furmahmg of elmtici~---------------------- 29, 6G6.29Rent of office mfi)------------------------- 960.00&p& and d&tiO~----------------------- 17,872.08Special investigation and mporta-------------- 45,200.00~tipment----.:---------------------------- 81, 56fi 66

~&dtm -------------------------- 827,186.25Unobligated b&ce -------------------------- 227.70Furlough and compensation deductions --------- 72,686.06

Tow general appmptition ------------- 900, 000.00

The appropriation for printing &d binding for 1933was $15,000, of which $14,983 was expended.

The sum of $6,780.82 was collected by this Com-mittee during the iisc+d year 1933, for scientific servicesfurnished private parties, and this amount was depos-ited in the Treasury to the credit of MiscellaneousReceipts.

The appropriations for the current iiscal year 1934are $676,000 for general expenses and $19,000 forplilltilg and binding.

On August 23, 1933, a severe storm inundatedLangley Field and 9 of the 11 Committee laboratorieswere flooded with salt water, reaching & maximumdepth of 5 feet in the full-scale wind tunnel. Damagealso resulted to the walls of several structures fromthe battering effect of waves and debris from Chesa-peake Bay, backed by winds of hurricane intensity.

The Committee had previously obtained an allo-tment of $200,000 from the Public Works Administra-tion for needed items of construction and repair.Immediately after the storm the Public Works Ad-ministrdion authorized the expenditure of as muchof the $200,000 as might be necessary to repair thestorm damage. This prompt action made it possibleto minimize the direct and consequential damages.The cost of such emergency repairs was $47,944, and

RDPORT NATIONAL ADVISORY

an additional allotment of this amount was subse-

quently made by the Public Works Administrationfor this purpose.

CONCLUSION

The Committee is grateful to the President and tothe Congress for the liberal support that haa beengiven to its work. It is proud of the contributions ithas made to the progress of American aeronautics.It is glad to have the opportunity thus to make fur-ther contributions to the progress of civilization, forthe history of the human race shows that man’s

COMMJTCEE FOR AERONAUTICS 35

progress has kept pace with improvements in trans-portation Each improvement in the performance,efficiency, and safety of aircraft incresses the relativeimportance of aviation to the national defense, andhastens the advent of the era when W travel willgrow with increased safety and flourish on -a soundeconomic basis.

Respectfully submitted.NATIONAL ADV-ISOEYCOti-E

FOR tiONAUTICS,JOSEPH S. Arms, Chaimuzn.