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TTHURSTON AIRCRAFT CORPORATIONAIRCRAFT & MARINE ENGINEERING - AIRFRAME MANUFACTURING
*OX 450 SANFORD AIRPORT. SANFORD, MAINE 0407)3 267/324.331S
*
Final Report
HYDROFOIL SEAPLANE DESIGN
Contract NOOO19- 6 9-C-04 7,,.,A
Report No. 6912
S'May 197n
Il D. D'
SEP 4- 1970
Prepared by: Nicholas J. VagianosVice President Engineering
David B. ThurstonPresident
Thurston Aircraft Corporation
UNCLASSIFIED
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MODEL _________THURSTON AIRCRAFT CORPORATION REPORT No. 691 2corn __________ SANFORD, MAINE DATE ________
IIOUTPAM.
TAH•,E OF CONTENTS
SECTION SUBJECT PAGE
NOMENCLATURE iv
I. Hydrofoil Seaplane History 1
TT. Description and Classification of HydrofoilSystems 11
ITT. Hydrofoil Configuration Data 17A. Hydrofoil Operating Principles 17B. Cavitation 17
C. Ventilation 19D. Aircraft Applications 19
E. Lift, Drag and Moment of Hydrofoilswith Zero Sweep and Zero Dihedral atInfinite Depth 19
F. Calculation of Cavitation Inception 21
G. Effects of Cavitation Number on FoilPerformance 21
H. Effect of Depth of Submergence on FoilPerformance 22
i. Effect of Hydrofoil Leading Edge Sweepand Taper on Foil Performance 22
J. Effect of Dihedral on Foil Performance 23
K. Effect of Hydrofoil Leading Edge Anglein Supercavitating Flow 23
L. Effect of Trailing Edge Flaps onHydrofoil Performance 24
TV. Strut Configuration Data 71
A. Design Factors Affecting Strut Selection 71
B. Drag 71
C. Side Forces 71
D. Typical Strut Cross-Section Shapes 72
E. Subcavitating Struts 72
F. Supercavitating Struts 73
MUDS. THURSTON AIRCRAFT CORPORATION EEPORTNo. 69126ONT, _ANOmolMAINK MTE
II I
SSECTION ;1RTn.TP1r PACE
V. Full Scale Hydrofoil Test Results 85
A. U.S. Navy JRF-5G Equipped withSupercavitating Hydrofoil System 85
B. I-RV-i (LA-4A) Equipped with ThurstonAircraft Corporation SuporcavitatingHydrofoil 87
VT. Hydrofoil Application to Seaplane Design 101
A. Longitudinal location 101
B. Extension versus Sea State Capability 101
C. Impact Load Factors and Bottom Pressures 102
D. Hydrofoil Size 103
VIII. Hydrofoil Seaplane Design Optimization 109
A. Design Factors for Integration ofHydrofoil and Seaplane 109
B. Stability and Control 109
C. Performance 111
D. Spray Patterns 112
r. Hull Design 112
F. Hydrofoil System Optimization 113
VTI.i, Hydrofoil Seaplane Development. 115
IX. Bibliography and Reference List 117A. Historical References 117
Ti. Hydrofoil Bibliography Lists 117
C. Hydrofoil Study Reports 117
MiuoL_ THURSTON AIRCRAFT CORPORATION REPORT NO. 6912CON__ _ _ ANFORD, MAINE DATE
I ~~~NOMENCLATURE l , i
aLift curve .Slope
A Aspect ratio b2/'S; and for foils with dihedral2(d/c) cot r
b Spcn, feet
c Chord, feet
cg Center ot Gravity
CD Drag coefficient, D/+p V2 S
CD Profile drag coefficientp
C Lift coefficient, L/Ie V2s
Cq Section lif-. coefficiont, L/j-•V2c
cLL
CL,d Design lift coefficient of hydrofoil (lift due to
bottom shape)
CM Moment coefficient, M/.pV 2Sc
Cp PPressure coefficient (p - po)/q
d Depth, feet
D Drag, pounds
f Trailing edge flap
F Froude numbe.r, V/q-g,
g Gravitational acceleration, ft/sec 2
L Lift, pounds
p Static pressure
q Dynamic pressure, +F V2
Re Reynold's Number, C cV//
S Projected area, feet 2 (S for wings; SH for hydrofoil)
V Velocity, feet/second
x Distance fram hydrofoil leading edge, measured aftalong chord, feet
y Distance from hy5rofoil chord line, measured upwa-rd,feet
MODEL THURSTON AIRCRAFT CORPORATION REPORT No. 6c 12-ORT SANFORD, MAINE DATE_
SPAGE -v
I - I0 Angle of attack; angle between hydrofoil chord and
free steam velocity vector, measured in planeperpendicular to hydrofoil transverse axis, degrees
W Central angle of circular arc hydrofoil, radians
r Dihedr;al nngle, degrees
Flap deflection, degrees
Sweep angle, degrees
/4 Viscosity, lb-sec/ft2
Density, slugs per cubic foot, ]b-.ec2/ft I
SCavitation number, (p -p)/q.
Subscripts:
C cavity
v vapor
Trim angle; angle between hydrofoil chord an-d aliplanereference line (equivalent of i:erodynamic incidence),
degrees
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 6•).1 ,CONT_ ANFORD, MAINE DATE
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I Hydrofo0il SOap] E-ie HiStoryWhile this hrief hiistory of hydrofoil seapi one deasitgn anid
development is not intptided to he comprelteiis1 ye, fin ei'fort he.ý-.
'I'lloman Moy.
t~sing water its rA test medium, Moy towed . lightweighrt. Ionit.oiii Engti nd's Suirie- tanal during 1861. '1'liý t.f-.-t veltic If. wanCit~ted with tliref c~inhiered planes of s9idihonic airfoil pin 'i le
pinned along the -ipanwi-ge axis Find moitriated b~elow thre keeýI * 'i'eboat, rose ahove the wR tor surface as speed was I rrCreHS-rse, W1n 1 0
tire inventor no tod thp p1 ones devel1oped Inci neao sel 1 1t ;id-( ttrim1-
tiied to reduce drag, as speed was increa~sed (eI.1).
Foret ell ing f-it ion figirr t ion ot thei l.lajggi C *C hir .L ill11K,19, the Fi'enchmrenr Emmanuel Farcot in 18W)9 and TiSsarldie r ii I 8')1
ho ti developed cra ft fitted with tinderwater, propell1ers and srIh-urrei'go~d inclined p1lanes. TissHandier' s "1glider boat" was a iso eqIirip-
Pfad withi wings, "S waS EA model craft huillt 1),N Clement: Ader illSAder' s design incoreporated two adjiistablhie n-derwtiter Low
f'ui.1Il Hnd a planing linr'izontal tail. Adel- Fiitirter' deveilope-d this( Onf :Lgiiration throiigl 1 90) into a v'ar'iabl Ic woop wing air , iirshrIolv-cluic) e having -t coricaye lower wing amnritaco to entrap the mu~crr Thion, certainly- a remarkable developrirent: hal f a r:eatnii y unlreptfjof, Ats time.
During 1897 a catamairan boat equipped with a series of f'olrrli i jm aspect -ratio liydieofoils. and an under~water' propeller dri\ven
;t~ steam engine was sucre ss fully 1.V l owil"o e thne Seine cir r'.ii'j one- fan at '?C mniles per hour. I iv aped by 11. F. 1Id 11 ips
our! omt~e kip snrer. this designl was itipuox)ed thl-origin I 907 ntv Fri i-h time it was powered by an Antioniette Itate 'na 1 ronnrbrrstiorrfnrtgine and was cApahl-o W' carry\iig two mten over tire watter iit a
r jfd ()f' thir ty fo Yu rmi lesi per hoair.
* ,.' Professor Enriico Forlanini of Milan f-pplited for, lu idriet,
fou Ifaet in 1905 "to permit booits anid fl v-igrr machines to 1liftoito'contact with tihe water surface when propelied.]. tire reby
oileiring mujch less resi stance arid as a consequience be copuulili o (f
at to niing muich higheir speed~s . While suilitabl e enigile s puo-exeutedFort-anini from attaining f'light, lie corrtiriied Iris experirrreiitsHitii cr ghi thre d eveliopinon t of' an a ir propell1ed k'eliri le errip 1ov int-g tlreorifginL t l adder' hy~d-r-ofoil system. O~ni.1t ill 1906, thi~crAftlIfJted (lear of' tlie Water and reaclied a speed of' '18 krot~s (?I'rimiplr I
190'7 iippears to liave heen the, First iicce Ierotiori poi nt 10l
luvdractf(A. 1drevelopmenirt. Inr that N'eanr: 'Ilvlllaad Wi lhir Wr' Lglrt"V aint liiur wit~r thre wo-r'k of' Phil lips ;rit(- oirrrtedp 1,ir11u'nrt , p-riwouinieu wl-thr cnpper. shieet liyrdot'ol 1s rolnrorrrd not at te-t h-t opter;tin tir' Miami hik~i-r at Dijut\arr, Ohio; G. P. Ntpler ariiiiiomi( erl l-;
(lull' ,pjt. t'ot' spri riig loaded \-a i'iihu1'- iriicdern e livdiuoftn It I I' t; tuwa Ild vi .y lft. wit'h ierv- to rlnritiur i ur st';hil e iI gl -t,,ut '
MODEL_________ THURSTON AIRCRAFT CORPORATION REPORT NO. 9CONY__________ SANFORD, MAINE DATE ________
British patent in 1911, there is no record that Napier ever builta working model ot zii.s symLet, whilh sicr tc the
beltind variable angle tirailing edge (flapped) hydrofoils; theAmprir'in L. E. Simpson developed the design for a variable inci-dence submerged foil craft; the Italians Crocco and Ricaldonibuilt and tested a boat equipped with tandem (bow and stern) sur-face piercing hydrofoils. Driven by cambered variable pitchreversing propellers of diiral sheet and a 100 h.p. engine, thisvehicle exceeded a foil borne speed of 50 mph while carrying twomen.
Also during 1907, the American Peter Cooper Hewitt developeda tandem ladder foil test vehicle which weighed 2500 pounds andreached '0 mphl; at this speed, only the lowest foils remainedsubmerged.
While most of the preceding development programs employedboats or boat-type test beds, much of this experimentation wasdirected toward flight from water as well as the determination of'section lift and drag characteristics using water as the fluidmediuim. Early aircraf't experimenters reallzed the advantages ofa large, smooth, and relatively obstruction free launching andlanding area offered by a calm watert surface - provided they couldovercome the dual problems of hydrodynamic suction and drag pres-ent during water take off.
Finally, the first powered airplane to take off from waterwas demonstrated at Marseilles, France by Henri Fabre on Marcch 23,1910. Employing a canard arrangement of three low aspect ratio15% thick cambered float/foils and powered by a Gnome engine,Fabre's design carried him a distance of approximately 500 yardsat a height of six feet above the water surface. The Fabre floatswere designed to provide lift whether running submerged, upon thewater surface, or in flight - and probably contributed the addi-tional lift necessary for a successful water take off with minimumthrulst.
It is interesting to note that on page 1116 of his 1918 Editionof "Military Airplanes", Grover C. Loening shows the Fabre floatto have considerably less drag than other known floats of theperiod and an L/D value of 6- over twice that of any other floattested.
Impressed with Forlanini's work, the Italian General A. Guidonidetermined during 1910 to achieve flight with a hydrofoil seaplane.Starting with Forlanini's -ladder foil system, which he soon dis-carded because of the heaving and pitching associated with dif'-ferential and rapid unporting of the foils, Guidoni equipped e•ic.hfloat of' his twin float Farman F.1 biplane with a tandem cuscadesystem of three positive d edrala hydrofoils per strut. Varia-tions of' this system were s,,ccessfully flown by Guidoni on threeFarman aircraft, the F.1, F.2, and F.9; although experimentationprobably continued through 1913, there is little docitmentation
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. ._9_,2COrr_ ""ANFORD, MAINE DATE
I I
concerning the detail design and test results of' Guidoni's uset'i' iA second period of accelerated hydrofoil aircraft development
began in 1911. In fact, with the excep~iuzn of .petonic flight,there is little in the aircraft field to date that was not triedin some form by or during 1911. This includes Voisin'.s amphibiin(u.ing Fabre floats), Curtiss' retractable laniding gear, andAvro's ventilated step floats. By 1911, enigines arid the .4tateoF the art of aircraft design had reached ;a Iuvel siichit:Glen Curtiss made his f'irst flight from watt-i, uiitil a pt.shetr ,I-plane equipped with tandem floats and a for'ward mounted -lx foot.,;;pan hydrofoil| the firs-t British water t•'ike O~ff wFAS F1(:c(,tTplp i~h.(1•
bv Cdr. Schwann in a tractor Avro biplane havinr'. ventilated steptwin floats each mounting two struts fitted with two cascmdealuminum alloy hydrofoils of 40 inch sparn aud 4 inch chord (Ftandem cascade system similar to Guidoni's). The foils were posi-tioned 4 inches apart, set at 30 incidence, hand vt camber depthof 8% chord, and the upper foil was located 20 inches below thewater surface. So by 19119 aircraft developed in Fr'ance, itFih,Great Britain, and the United States had sur:eeded in conductin,sus.tained flight off water.
Another 1.911 American seaplane, The Michigan Steel HlontCompany'as "Flyinp Fislwt was equipped with a sing] e, beam, width,narrow chord hydrofoil mounted below the a]•uninum hull. A .iiigl,seat tractor flying boat of short wingspan, the "Flying Fi.1h"skimmned along the water" suirface supported bh\ the flat hyd 'ofot I.anol n planing srct.ton of' the hull afterbody - possibly the FirstplInning tail hill. During 1911, this design trave.Ied from D.tr'oitto C1evelanl at an aver'age speed of 50 mph, -ilthough •,•lainattlmsr)pou- of 70 mph wepv rfacorded when the "IIF.ying Fishl" IIf'ted c,,,i'of' the water except for the planing taXI.
The first significant attempt to develop an airplane capaldleof irough water or open-sea operation was supported by the BritishAdmiralty during 1911. Lt. Charles Burney, 1?.N. conducted towtingexperiments that year leading to the design and developmenrt oftile Burney X.2 during 1912, and the final. X.9' conf'igurationr of11iI'l intended for shipboard stowage. (Fig. 1. ) hnifl].rneced by thewor1 of' Forlanini and Guidoni|, the flufrie' 3 esi.gu'is employed 1 sp] ltTictiens cascade hydrofoil svstem with two st ruts forwi•i'd fnd oneaft. Water taxiingr power was supplied bI, small counteri'otatirnipropellers tandem mounted between the forward foils and drivenf''orii the engrine tli'ongli a clutch sNstenu. Tn theor'v, tile wv-to-propellers would got the X. 3 foilborne, thie I 'ight propel le' worldhe clutched in, and take off throug1 voulri. sens completed inri rp]rune fas9hion. In practice, vario-s stahilt it prohisll]-m r-a•u. itedfrom both water and air torque reactions when tihe respectivepropellers were engaged, compounded rio doubt by inadequate asov-dynamic control during unporting. Wrecked duiI r.ug m towing eni-counter withl a hidden sandbar, this tutes't ing pro.ije(t waslorm rinated during late 191.3. Tire v•i'iou- torquie pro11(s•,li hiIinI, f'.'
MODL. THURSTON AIRCRAFT CORPORATION REPORT NO. o- 2CON__ SANFORD, MA11A1 DATE
Fig. I
Burney X. 9 Hydrofoil Seaplane
Tiet,jens Split Cascade System
Power- Plant: 200 lip Canton-UnneSpan: 57 1- 1 Ol
Length: W6-8" IWing Area: 500 sq.ft.
MOD _________ THURSTON AIRCRAFT CORPORATION REPORT NO, 91CANT-. SAMFORD, MAINE DATE_________
PI
t 1A X. q wrAi a AmlI P.C4 -- 1-~ ~ h f ~In 1929.
Durin, 1914 the Wright brothers were again testing hydrofoilsin the Miami River. Their main interest Lay in stopping waterfrom breaking away from the upper surface of cambered foils toosoon (speedwise) and thus preventing the subsequent loss of lift.Tests were conducted with cambered sheet steel "hydrovanes" havingan auxiliary narrow cambered strip of steel placed Just above theleading edge. While this slotted hydrofoil was apparently success-t'tl in delaying breakaway beyond the speed possible with a plain(subcavitating) hydrofoil, it was only applied by tile Wrights toone seaplane design built in 1915. Possibly they were reallyseeking a means for obtaining an improved C1 for their aircraft,
thit if so, such a design was never flown by them. At this sametimeHandley-Page in England was wind tunnel testing and develop-ing hi.s slotted wing to a new level of lift and stall attitudeeapability; apparently neither group being riware of the othersefforts in the same field.
World War' I terminated hydrofoil seaplane research for maanyyears, until the series of Schneider Trophy Contest races reviveddetermined interest in the development of high performance waterb;Ased aircraft. Although the only seaplane attempting water takeol'f from Lydrofoils never made tile starting line, the configura-tion and design data for the Italian Piaggio P.C. 7 represent nhold design attempt to achieve seaplane performance comparablewith landplanes by minimizing frontal area (Fig. 2).
Designed by Piaggio's Chief Engineer, Giovanni Pegna for theI1029 Schneider Trophy Contest and financed by both Piaggio and theItalian government, the P.C. 7 was a relatively small airplaneof 3709 pounds gross weight. Described in Jane's All The World'sAircraft of 1932, page 232c, and more fully by Benjamin Posniak(now a Senior Pro j ect Manager at N S R D C ) Inan article for tile Italian press published in 1994, the P.C. 7used a split Tietjens hydrofoil system having two foils forwardinstead of floats and two small foils superimposed aft below thetail surfaces. Initial tests revealed difficulties with the waterscrew due to torque as well as clutch slip caused by oil and waterseepage; when attempts to correct these problems proved unsuccess-ful, further development of this interesting design was abandonied.However, since this configuration was so far ahead of it, time,and could serve as a stepping stone for future high performanceseaplane development (with jet engines precluding propellerproblems), a few of the P.C. 7 design details are presented forireference purposes:
Type: Experimental, single seat cantilever monoplaneracing seaplane.
Power Plant: 850 lp Isotta-Fraschini engine of' 12 '?, ctindersWing: Cantilever; 3 spars; plywood covered and watertt'ght;
wing surface water cooling radiators.Fuselage: Built-tip watertight plywood strtcture; fiel. in
fuselage.
MODIL THURSTON AIRCRAFr CORPORATION REPORT NO. 091 _2CON_ 8ANFORD, MAINE DATE
PAIII 6
Fig. 2
Piaggio P.C. 7Schneider Trophy Racer
Tiet~jerii3 Split Flat Monofoil. Sy'st em
Powe~r Plaint: 8-C)n lip Isotta-FreachiniLengtfi: '-?( 0"IWing Areoa: i06.3 sq. ft.
MODEL . THURSTON AIRCRAFT CORPORATION RtEPORT No, -CON? SANFORD. MAINE DATE ________
I
I ITail Surfaces: Same as wing; watertightFlotations Watertight structure having two watertight
compartments in fuselage plus welded aluminumalloy tanks; rests on water by floating onthe wing, fuselage, and tail
Operation: The 850 hip IF engine drives the water screwuntil the P.C. 7 is foilborne, at which pointthe propeller is clear of the water and engagedfor flight.
Span: 22'-2" Heights 8'
Length: 29' Wing Area: 106.3 sq. ft. total
Weight Empty: 3093 lb. iticludirg fuselage ara-
Useful Load: 616 1. 90.1 sq. ft. net
Gross Weight ,3709 lb.
IK-timated maximum speed: 373 mph.
Following the failure of the P.C. 7 to achieve water borneflight, primarily due to mechanical causes rather than basicconfiguration, hydrofoil seaplane design received virtually noemphasis until Edo Aircraft studies begun in 1957 developed theJRF-SG amphibian equipped with a Grunberg supercavitating hydro-foil system (Fig. 3). This configuration was extensively evalu-ated by Edo and at the U. S. Naval Air Test Center, PatuxentRiver, Maryland through 1964.
The Grunberg foil system aq adapted to the JRF-SG consistedo a supercavitating hydrofoil near the air'plane center of' gravitNi.ii•d two planing bow skids; this arrangement was used to permitevaluation of the hydrofoil while providing safety in the eventof foil failure. This system used the largest supercavitatinghydrofoil built up to that time and the first supercavitatingfoil mounted on a seaplane. The bow skids erved the dual pur-pose of (1) properly trimming the airplane during transitionthrough the hump speed regime and (2) preventing the air-planefrom diving if the submerged foil failed. Both the large hydro-foil end the bow skids were retracted hydraulically to permitramp approaches and land operations, and were locked in the upand down positions.
The water perfoT'mance and test result.s obtained with theJRF-5G are discussed under Section VI of this study.
Subsequent to the JRF-5G program, Edo initiated design andtank studies during 1964 to develop a single, surface-piurcing,supereavitating hydrofoil for application to the Grumimain HUI-1.6Albatross Amphibian. To flight test this concept in sc-]r ,'orm,
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 69)CONT,_ SANFORD, MAINE DATE
(I] PAGEI
FRONT VIEW
SIDE VIEW
rig. jJRP-5G AirplaneI BuNo 37782
TEST AIRPLANE WITH GRUNBERG HYROFOIL SYSTE24
Span:Length: -31-1Wing Area: 937) sqt. ft.Gross Weight - 9570 pounids
MODEL.________ THURSTON AIRCRAfT CORPORATION RE~PORT No, 691 2CONT__________ SANFORD, MAINE DATE ________
SPAE g I
the Thurston HRV-1 (Skimmer LA-4A) Amphibian was equipped in
1966 with a single foil similar to the Edo design bmt ]/•.47-cale size of thfit nece:ý,qary for HU-16 eva]nliition (Fig. 4).
This sipercavitating foll was flown on t1i- HRV-I dur-ing
Ito November 1966, r'epre.tnting the first ;<iowii I'light ol' an
a irplane equipped with ii -ingle surface-p ie iciriL Iydrol'oil.,
The detail flight test program was successful,]l completed with
4I1 data runs recu:'d(d; opc,!rational restilts n', presented in
So,:tion V.
MODIL THURSTON AIRCRAFT CORPORATION IMPORT NO. Q) 12,,,CONrT UNFORD, MAINE DATE
A ZA 170 5Q Fr N1-LV-i A,-LMr~Ej
7&5T w'r. 23c00 LSS, JýP LA' If , r i Ns
Lu iI-4 HYf)I2oF-olL- Q0. I
MODEL THURSTON AIR~CRAFT CORPORATION RIPOM, No, 6c 12CON?__________ UAJIORD. MAINE DATE _____
MIIT. Description and Classification of H-vdr'ofnil S-ystems,
Since no comp rehenisive de script i on of1I tlis vnrl jiii hN-d '- '0(ii Isystems is available, an effort has been ma~de to classli t'N tfestedas well as possi hie nirrangements. Refer to i' itgi rns ') Ilirooolgh 21
Fig. 5. The Single Hydrofoil system consis-ts of' one hydr~ofoilIplaced slightly ahead of the cg, with sonic type of vehicle sta-bilization providled in addition to the LoiLl; such iis the wing,tail, and control 8surraces of a seaplane. The singl~e TiydrofoilHiipports a predetermined percentage of tlie gross weight at unpori-1lo g. Conceivably the single hydrofoil arii'nugement could be either
ft monofoil, a hoop foil , or a ladder foil.; tho Thin-rston HRV-1Ithe only seaplane flown with this type of' a rrangemenzt , employs asHingle, positive dihiedral, 5uper-cavitatluittg ionofoil..
1 o.6. The Griinbei-C sys-tem employs a inn i~i f oil. (cant irniciis,ior monof'oil ) positioned behind tliiý ig, withi two hNvd ir)n- k
()t floats for-ward ý-kimnmiiig the water suirtnire ;trd Stahl I i'zirip t. i,-liic, [5. With tfii.ý rcvsign, the main foil .i-ugiei 10
uitOf the MImportillog de!Sign load, WIAiI V s011li.l~.illj', jIIIui*W'il-
%ide a small1 percentnt,-eý ol the designi li-I ( witht resApoct to loanddistribution, the Gvitinherg System is simti.i or to the Caniard .te)This foil arrangemenit has been used on the JRF-5G seaphine (seeFig. 3).
Figs. 7-1-0. The Tanidem Hydrofoil systems consist of' foil. ararango-motits at the bow and stern with each foil array cairrying about50 of the unportirig dlesign load. The r'oil s coul~d be mono11foils,!split., or continuou!4 hoop or ladder foils, or A Comiii)iatiofl ut'uiijv of' these; liowe%-ei.-, most of such arrangemrents aire nlot pvafctIion I
Mins.ideririg the as~soriated drag, weight, rand cost.* A,, A result,i his system is iinsiiitabl a for seaplane applicat ion compa ree tothe singl~e hydrofoil system. Fulrther, 1imndeSjiallMe 1 stPrn 1 and1 utigi Luidinal trim probli es could devel op diitring tinpo iitilug in lien' v'a k R
Figrs. 11-1)4. The Tietleris Hydrofoil syst eit ti hau a arwaird mainl1Iiydro foil that carries most (60% - 90)%) of' ths tinpoitii hg, designtload, with a smaller hydrofoil arrangemterit in the stern c~arry ingt he remainder. The lifting surfaces at the ho0w amiid sterin ra ildconsist of mono foils, or' split or' cornt iinioii s haonp or' ladd er i' i~d n-l'oils ; again these arrangettents are not pianc LIcal 1,o' niirc r; lftappi icaftioln. One split Tietijens nvi'i'nigemiuiui that wii s te.- te-d 1I'oiseaplane operation, the Burney X. 2 and X.13 of' 1 91.2 and 191 '1 haldtwo cascaded foil, strutts at tile how and a s;1im ihir s;Ia selol' foils at the stern (see Fig. -
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO, 69 12...CONT &WNORD, MAINE DATE
SPAl| 1 2
Description and Classification of Hydrof'oil Systems (Con't)
Figs. 15 and 16. Thle A. G. Bell Hydrofoil system, named after.,the inventor who employed hydrofoils on his 1ID-1 4 boat of 1919,is one of a number of move complex hydrofoil systems. Tie avir'ange-ment consisted of' a main foil at the cg supporting over half ofthe load, with smaller stabilizing foil arrangements at the bowand stern. Bell's original split system hlad two ladder arrange-moiits amidships, with smaller single ladder' arrays Fit the bow andstern. Due to drag, weight, and cost, thiis and similar complexs%,vtems are consider'ed impracticnl for aircraft use.
Figrs. 1.7-20. The Canard Hydrofoil system positions a main hydro-Foil arrangement located behind the cg carrying 60%-90% of theiinprting desi.n load, with a smaller hydi'of'oil located at thpe
how. The array at tile bow and amidships couldi consist of mono-'ols, split or continuous hoop or ladder foils, or a combinationSf' these. Again, this system results in too much drag, weight,wid cost to be practical for modern aircraft application. How-over, one split Canard system, the Fabre, ising cambered hydrofoilfl'ats, achieved tile first powered flight from water in 1910(Scle Pg. 2). Using another design approach, Guidoni flew a twin-Float mounted tandem split Canard system successfully in Italydliving 1910 and For several years thereafter (See Pg. 2).
It is evident that many of these foil systems overlap. Sincef'oil arrangements are frequently mentioned by the designer's nameas well as by planform arrangement, it was considered advisableto present configurations under both classifications.
A comprehensive illustration of possible hydrofoil arrange- -1ments is presented !n Figure 21, together with conventional no-menclaturie for each configuration.
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 6CONT SANFORD, MAINE DATE
PAGE
FvjLE 14YRPIu Sys TC-MT~ ERG 5 rL4Am
1i? -3 TR11.1 .1A
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* IMODEL____ THURSTON AIRCRAFT CORPORATION REtPORT ma. 6- 6912I ~ UT IIANFORD, MAINE DATE_________
II
T~eT~#J HY~o~OL/~r~M~PAIR 1!4Tte:T JtW H', P-or-01 ',/ST-. L i 5
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MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 6912CONT SANFORD, MAINE DATE
PI E - II
ICAQA ZLD H-VZ0F-COIL I I
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FMODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 2•LL
CONT__ __IANORD, MAINE DATE
t .. ' .... .• '- .. .• • -i ... .i -i . . 1
F -21 FoiLl A1AýJ6 &•JT5N1 _ t n I n I I- 1CI
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NOMENCLATURE
a. Flat monofoil k. Split dihedral hoop foilh. Positive dihedral monofoil 1. Continuous flat ladder foilsc. Negative dihedral monofoil m. Continuous positive dilhedrald. Cantilever monofoil ladder- foilse. Cascaded flat rn. Continuous negative dihedralf. Cascaded positive dihedral ladder foilsg. Cascaded negative dihedral o. Split flat ladder, foilsh. Continuous flat hoop foil p. Split negative dihedrali. Continuouis dihedral hoop foil ladder foilsJ. Split hoop foil q. Split positive dihedral
ladder foils
MODEL_ THURITON AIRCRAFT CORPORATION REPORT NO. 61Q1.2€ONT SANFORD, MAINE DATE
I J I
III. Hydrofoil Configuration Data
A. Hydrofoil Operating P~iuclples
A hydrofoil is the marine version of the airfoil as u1sedin water to create dynamic lift for the support of' a vehicle; oras ai] element in a propeller type device. Subsonic airfoil sectionshapes perform well as hydrofoils when operating at low forwardspeed-5. At equal Reynold's Numbers, the forces and momr:tis createdi n ti•i and water are essentially ideoitical. for these foils whentile flow is completely attached. A foil operating in thi.-i conditionis s;i d to be "fully wetted" or "subcavitating".
At higher speeds, separation of the flow occurs causin&changes in the forces and moments and resulting in a considerableloss ,,f efficiency. Separation of' the flow is termed "cavitation";when the entire upper surface of a hydrofoil is completely free ofattar-fled flow, the foil is considered to be "supercavitating".
For operation at bigh speeds where cnvitation cannot beavoided, hyidrofoils specifically designed t,) operate in a super-(a Ivltating regime are superior to foils des Igried for suhbcovitat inffi i],,. Slpercavitating hydrofoil sections are characteri/,ed by ashavp Leading edge with entrance angles of about six degrees. Themost common section shapes aret plane faced wedges with blunttrailing edges; the ogive, consisting of convex circular arc sur-fatces with sharp leading and trailing edges; circular arc concavecambered lower surface with cotoured upper surface; and more complexshlapes designed for increased efficiency, the best known beingdeveloped by M.P. Tulin and V.E. Johnson, Figure '22 (a) and (b).
B. Cavitation
A hydrofoil moving through the water in a subcavitatingcondition and at an angle of attack producing lift creates aninc-rease in water pressure on the lower surface and a decrease onthe upper surface In the same manner as an airfoil. The p'essllresare a function of the hydrofoil shape and: 1) velocity, 2) angleof' attack, and 3) the operating depth. With increasing speed andangle of attack and decreasing depth, the pressure on the uppersui,'face reduces until the pressure drops to the vapor pressture ofthe water as determined by its temperature. When this occ'i rs, thewater starts to boil or "cavitate" at the chord point where minimumpressure occurs; normally coinciding with that of maximum thickness.Further increases in speed or other factors causing additional
decrease in the pressure, lead to enlargement of the cavity alongthe foil surface until it covers the entire sur'face. Still furtherpressure reductions cause extension of the cavity several chordlengths behind the trailing edge. The process of cavitation is
MODL THURISON AIRCRAFT CORPORATION REPOnT No. 6.2.CONT IANFOD, MAINE DATE_
MIB•. Cavitation (Continued)
similar to the stallingafa wing and is accompnnied with a similarloss of lift. Since this occurs with increasing speeds, it has asignificance similar to critical Mach effects in aerodynamics.
The aerodynamic pressure coefficient, Cp = - which
exists on the surface of an airfoil in subsonic potential flow isindependent of velocity. The same coefficient in hydrodynrmics Isindependent of velocity uip to the point of cavi tntion inception,where flow separation occurs. In the zone of beparation, thepressure coefficient has ,eached the lowest attainable value for'
cavitation and is defined as CPi = ._____ , wheve p i the Vaporq 0 0
pre~ssure of the liquid, p,, is the static pressure of' the liquid at
at the operating depth, and q is the dynamic pr-essure. In hydro-dynamics, the negative of the pressure coefficient is used and
defined as the cavitation number: 6" - Pv.
Figuires 22 (a) aFnd (b) show the shapes and equations f'or fo,,rsupereavitating hyd rofoils.
The effect of .-<'e cavitation number on the flow patternnboiit nr hydrofoil :Is 3chematically illuý- rated in Figure 2?. (c).
Tire patterns shown -tr'e iot static but are% t-pical averaee of adyvraml.c situation. At zero speed, Cr=oo ; as speed incrcases, 6'decreases, eventually reaching cavitation conditions. When cavita-tion occurs, the value of 6r is known as the irncipient cavitationinumier, being equal to the negative of Cpmin; a'i = GCpw.. 1 As 0-
continues to decrease, the cavity size spreads over ;,n-, f,.t L surface,and goes through a phase which creates foil erosion u'u.r c avita-tion. When the cavity lengthens to a collapse point -iý :iat thepressure pulses created by the cavity collapse clear t; , ailingedge of the foil, the erosion phase ceases. In this .oew!i~ion,however, the eddies and the re-entrant jet which exist . the down-streatm end of the cavity may impinge upon the foil trailing edgeand cause severe buffeting and foil vibration. Upon further reductionof Or , the cavity lengthens downstream such that the re-entrant jetis dissipated before it reaches the trailing edge of the foil,Figure 22 (c). In that condition, the flow is said to be super-cavitating. Thus, cavities associated with supercavitating flowsare relatively long, usually well over two chord lengths, and arefilled with either liquid vapor or foreign gas, or, a mixture ofboth. Flows in which the cavity is filled with atmospheric air havecome to be called "ventilated" or "vented" flows. The term "Srper-cavitating" applies to all cases of sufficiently long cavities,regardle-ss of whether they are filLed with water vapor or ,i i'.
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 6. 12.., S.ANFORD, MAINE DATE
C. Ventilation
Naturally vontilateci fl~ows frequentL'y ut-utir dtixLing liydrufoiloperation due to the pToxililittV Of the lifting and ,supporting dev4 ~e'ito the free water siil'rfne. Natural. ventil'it ion i the passajfe (-fat iict-,pleric ait, iinti the I ~'pressiire reglinri.- ot, tile Upperol I the hydrofoil, it-ikingr 'th along tie I ,% 'ýx essureP sid!fý astirfaFce piercing iloi long the hblunt iii-;ii inp edge of a srf'acFi piercing stri'it. or foil.I Natural k'ontlt'ji a P occuris onl1y atfter'Cavitation has boone~-itL.~~~ and de 1 uj. aiutl to Its fiill.
Where the foitl is operating undor partial crivitatiot- conditions,ie. not siipercavitieting, ventilation cnn re-3ult in the immediate loss-of' 71 percent of lift, dropping the supported vehicle into the water.Na Ltral ventilation occurs at high speeds, iin roiirhi water and duir-ing unporting and tuzrning mtaneuvers. Once \Pritila-tion has beenestablished, it tends to continue even though cotiditions become lebefa vorab'le. U jnfo6rtitnatel1y, the onset of' natto al \P31tilation cannotIjo piodicted easil% Potit li fiory or model testsý, iiid stultal-ly sittipl '
]li tg' laws -for vif i hin onset err- not iI~ii tilkle.
Forced 01 u c IIa vent ila Vltio i s ,,' ItttIi. Lshed by arti i V ci-aillN isupplying eli' utide-' pi~essure to that poi-ti on (if' the hiydrol'o.I.IWile;',,--tie cavity Is desired. In this case, o!!;tuibluished cavitation1., n Li im ,es sary * Whbait the cavity size i5 chiiing-*'d hy u ii lug fore: edai'u, the cavitation rtiumibei' will change and re.suilt in change., ini thelif iii.nd drag;
For a foil that is operating under' sipeircmvitating condItions, -vent -I Itiuun will hiivo little,- effect on fhe in1[ft and drag. Fo-r vetiiti-IhatIIon, the cavitation number is computed by using the air pressiirein the cavity, p , in place of' the vapor pressure, p * The character'-
ist~ics; of optimum ventilated foils and superca-vitutting foils areidonti cal if the cavitation number is the samie.
D. Ali-craft Applications
Since cavitation and ventilation cannot he avoided f'or air-* craft applications due to operation at the water surface ond at
high speeds, hydrofoils for aircraft use should be designed to besupei'caviltating and rea-.dily ventilated. By uising this approcach,the l ift and drag on the foil will remain smooth end continuous, and areessential condition,- for successful liNvdrofoi. aircraft opo t'a tion.
*E. Lift, Drag and Moment of' Hydrofoils with Zero Sweep ind - i-Dihedral at Tnfinite Depth
The lift, drag and moment cfiaractei'ist ics of' hydi'o foll's are--- ' dependent on the samte factors of shape, attitiude, velocity aind fluid
MODEL________ THURSTON AIRCRAFT CORPORATION REPORT NO. 6 1CONl SANFORO, MAINE DATE_________
SP~iIE , 20 IE. Lift, Drag and Moment of Hydrofoils with 7,rn qwo•p -•r eo
Dihedral at Infinite Depth (Continued)
da.Ait, that affect airfoils, but in addition are dependent upondepth and cavitation ruimber. With these additional parameters,
the amount of data required to catalog hydrtoftil characteristics
becomes exceedingly large. In order to avoid the use of a greatnumber of charts, the approach taken in this study is to show thecharacteristics of typical hydrofoils favored for aircraft use,as well as the effects of these various factors on performance.Furthermore, the volume of experimental data in the hydrofoilfield is far from adequate, thereby inhibiting any comprehensivecompilation "of systematic data.
Figures 23 and 24 suhow the variation of lift, drag, andmoment coefficients and the L/D ratio with angle of attack for suih-cavitating and supercavitating flows. The data were taken fromseveral sources and were combined in the fioires to compare thecharacteristics of the different types of foils.
Figure 23 bhows the subcavitating chlr;.ctei istic.s ol' aconventional airfoil (NACA 661-012), a subenc't•tting liydrol'oll (DTMi"Sea ;os HF-I), and six der'ee wedge (opti.1•tiu f'or supelcavi nt•olo)wit a blunt traili tg edge. The lift curve slopes, of the wedgeappear to be higher than the other two by a sma]l amount, but thedat;i did not extend sufficiently over the railge of aspect ratiosand maximum lifts to permit a through comparison. The wedge ap-parently produces lift with characteristics similar to foils designedfor subcavitating flow. The drag of the NACA 66 1-012 foil is con-siderably less than the wedge at those low angles of attack wherethe L/D of the NACA foil approaches a maximum. At higher anglesof' attack, the drag of the NACA foil exceeds that of the wedge,while the L/D diminishes rapidly, and if extended, might drop helowthe values for the wedge. Moment data is provided and is of primarysignificance in the structural design of the foil and strut.
Figure 24 shows the supercavitating characteristics of thesix degree wedge, the NACA 66 1-012 airfoil, and the Johnson 5 termsupercavitating hydrofoil. In supercavitating flow, the John-son foil shows slightly higher lift than the wedge end the NACAtoil lift degrades almost immediately, developing at most only 21percent of the lift of the other two foils. The inferiori tv of afoil designed for fully wetted operation under supercovitatingconditions is clearly shown here. It is interesting, to note thatmaximum L/D values for supercavitating foils are reached in thefirst four degrees of angle of attack from zero lift, too near zerolift for sustained aircraft operation. Since normal trim angleswould be in the range of about four to twelve degrees above thezero lift angle, normal supercavitating foil operation would centeraround that portion of the curve producing 50 to 75 percent ofmaximum i,/D. These lower L/D and consequently higher draf; vaLueswould be occuring at
MODEL. THURSTON AIRCRAFT CORPORATION REPORT NO. 6CONT SANFORD, MAINE DATE
I!1 ~PAGE "
F .LLift, Drag and Momi-tit .)f Hydr-ofoill MWitt) Zf-t Sweep al~id 'Zero
Dihedral at Trifiniitu D~ epth (Coiitintied)
uiipurting which is the critical phase of the tnk('-nf from a pei-Torm-ancn and coritrollahility rFtandpoint. The high 1I ' /r!.-snciatedl withthe low angles of Attack woujld occur at the Iiigli speed end] whereit im not as critic-al.
1. (. 3cu1 tion 01 -"ovitat In EInception
Fig-tre ?5 (a) Is a nclmograph foi tbe i I : lnion ol' thesper-d at which cavitation blegi ns. Data is pres'' ifed for' F twodirti-nsional foil operating in s4ea water at a ta'iirpe~ii ct'ie of, 5.5Fainit i'ucjiires knowl-doge of' tlif, inception crtAA1. LaI. o iiiiii11ela. For tjHatIn I-'. 'The valiues obhtained ioxe low in compai'I hoi 1.o the tlui eedowi i-oional case. Howexei', nio known work It 1.,'' pukl1 ishod r'over'-
iai- 'j three dim!ns-iiniii I Or' the ( f~fu:( t. t ta-,I~poi I ( \tlioin,- ati lift anal *IVni. t
f -(ar' pressllr'i var ith i o mu witli W;ii1 - tCIjwri-'EO.
t ii'0 ra-sented Il ~in 'u F i 'r e '15~ (b).
G,. I l'i~cts of Cavitation Number on F~oil P1eito rwarlcp
Figures 26, 27, and 28B show tire variations9 of- C , C Da nd 1./D
with cavitation number for the NACA 66 1-012 airfoil. The horizontalpot i inri.' of tire curves atre regions where ca\'itntt Aonl doos riot exist.Wit- :itation hregins theret is a9 rapid dercei'-a(-v In 1,/I) vato eve,
Figrure 26 'Faows an Uiti- ease in l ift with Itsmo 1l.1 amtouints .of'
Jt fion at ringi rs of att-iirk greater than, thiieo die~ees. Atilion, the iiii:reani Iii dIrag is proportionate I\ gt'r Pter titan
111t ,,:rease to 1 1 Ft Fni'thev reduction in thle ca ivita t i n numbe r( .n4 the drag cov-:ffrlt~erit toa peak and then docreraso. Tihe ii Pt
coolr' I c rant, lloWeVe t' , decr-eases rapidly- wi thr cilvi tnation ntimber andt 11- dilctliot Ill thog ( oefficient mve.i'eiv onnses a iedtiction in the
Io)f4 the [J/D 'n tin curvves.
Piguires 29 tl!Tr01?7I1 41 'Ib qow thre variiatl. ons. of (I' C~ 1), C M an d
1./P with cavitation numnber' for oi six degree wedge hydirofoil withthin'tt trailing edge. at aspoct. ratios of one, two and fonil. The i ft,d r,'L: and moment plots h1ow 1lines of constaiit caa.-itv length, givenlin chord lengths of x/C. The lift plots show that the lift startsto dec-tease when the cavity size equals one chira d l ength. Thre drag-changes approximately in proportion to the lil't With the resuiltthat the 1,/D ratios tend to remain contant~r or Jnl-ptit,.~ gitlAspe-ct r-atio does niot affect Lift and dvarg ~pr.i lr~la gi ight. improvement of 1,/ r'atio does occur', withi inc-renainfg Isjpect-ratio.
MODEL_________ ThURSTON AIRCRAIFT CORPORATION REPORT NO. 6(CON?__________ BANFORD, MAINF DATE _____
H. Ef'fect of' Depth of Suibmergence on Foil Pert or11llvCe
Tire effect of depth of submergence on thfe lift riirv#- slopeofsubeavitating hv' drofoil is of various a~spect rni' ios i!s shown ill
Figure 11 1* The l ift uriive slope decreases fis flit. foil fippr-oacht-s
tho surface, with rho most marked reductioifi oý, 4tt-iiLe VVILhlL Mlech,)rd length of tire witter s-urface * The% of I'ht on foiils .) a spetcrat ios less than ten is essentiallv the same.
For supercnvitatingr foils, tile,, effect of' depth on the eff'eo-1l1vo angle of attnek dune ton camber also decrent,-) rapidly within
L onle chord length ot' tho wsiter Purface, as shrown in Figiirie 4:2. TheviLation of lift atin dru~g coeffici ents due to -,0hrnergeu cr', within
otif. chord length of.' the suirface arqre given in Fl gt.jre 11'3. 11 is shownrth.if for tie, Tufl-Ii-Bitrka it, (cambered) foil , Chua Lift find Irag (I., unift.
vit I However, ii-~ fl at plate lift does .IncrIeI.5.i slipigit.ly as theFoilI approaches 1rt muvrirfco, with the dravini iemaitirun nsý- etitiall.y',on t ant. Figui-s 14, (Ra) Itill (h) -;how thllitt, th0 itrej11IaSO finl :i ft'-nPft'icient near tilie izr-face is slightly Iriglirer for higlrei, aspectr'atios.
1.* Effect of' Leadl.iirig E ge Sweep and Taipoi, on I'nil I PeiT Fe rin rce(
The most stgituloiiriot. eff'ects of leadtinfg Pcdge sweep) onhvd-rofoil a-r.e a dpkxyi iri CHvitation incepti on ant( clocreiise(l I i ittL/D ratios, and l.ift' cuirve slopes. Sweep is highly advatntageoutsfor subcavitating systems, attempting to achiFeve maximum speeds.Conversely, sweep hats a detrimental effect ori sripercavit~tring designs.(uthe to cavitation delay an'd loss of lift. Taper iratio has negligibleeffect on cavitation speed and force characteviirticA.
Figure 45 is based on analysis and shiowm the effects9 ofswoep and aspect ratio on the lift curve slope of sinbcavitntinghrydrofoils. The lift curve slope reduces as aspect ratio becomessmalnler and sweep increases.
Figure 46 presents the physical characteri~sticsA of' Fourhydrofoils of various sweep angles and taper ratio-s but of equalarea`. All have the NACA 65AO06 airfoil section parallel. to tilefree stream velocity and were constructed of heat treated chrome-vanadiumn steel having a modulus of elasticity of approximately .'3million. The hrydrodynamic characteris tics of' these foil.-;ia u givenin Figuires 47 through 511.
Figu-re 47 shows thle anguilar deflection of thle swept-hackhrydrofoils and the -resulting reduction in maximum lift loadingcapability of the 60 degree sweep foil due to twist.
Figuire 148 (a) through 51 (c) present thle lift, driag and L/Dratio data for tire foujr foils.
Ftgiire '): shows the increase of cavitaitioni Incepti on speed
16withi sweep ait v-arious coefficients of lift.
OO THUR$TnM AIRCRAFT CORPORATION REPORT MO. cj(.jCONY__________ SANFOR, MAIME DATIE _______
PAIIIEfetof Leading Edge Sweep and Taper oni Fuil Performance
Figure ti'j shows the decrease In lift r1i ;t ratio with swe-31
rit narioiisq coefficients oi lift.
Figure 54 shows thamt taper ratio has ýislight effer't. aporau/n ratios.
J, Effect of Dihedral on Foil Performance
Dihedral is an impUv'Ltnt desigii parameter, for' dArem .,f'tapjplication, since thle hlxvii ufoil in t~i s ca-ýse shoil d irvi i 'sh~li~vhie of th,ý surface pie-rcing type.
The surface pieficing hydr~ofoil hast a Mi' tuiral yen Liligt Pot' h:liocl, tlvere.oi-e, tends to 'n--At rea'dii ". Pria' to i till v-ent iIntirlot-ce S pircoda c ed by the -I- dagree wedgre a iv' s' ivrtF inJi's -(
isv the livies labeled fiii 1\ attached (hasp. -' or!) . As st ped or I
our!t , e of' attack arei-P e'"i flow .seplfii'tri (A :clt's9 or' (11 le io'l,pann1 stu(f lld faui1l kva'st-j I t i1ni is achiepved. I. I'[t fol~o 101,1
t' ediirel c~ i (I... ral' i I-Ati t-re lp1 AVEII [\ [tI, Inisl fo ' ll Is\Yeni lated. 'Pile direig t'toz'ce,, site given liit I q-;u i e '55. (1).
A factor whiich bear~s mention is the chiangte of a;.3pect raitiowithi immersion of a surface piercing foil. * ince aspect ratioaft tts lift and dr~ag, the relationship ov Isenisii-ion to as-pectrat~io shiould be given cons-ideration when designing a sur11facepier~cing foil system.
K. Effect of' Hydrofoil Leading Edge Angle liti Siitputcavitatinig P'low
ledngidedecreaises, inel requiiring teentr~ance;iiý, o b fie irkrt umpermiiitted hY sti. sctihral consideis'ntl nts,
A Inctiluded angle will, allow opesi V.lust i i ilowes stt'isst,5 iiii! uotiseq~itettjti.v. ltilghsui' Is/p a, )i- ut"ý gjI\ 1:5 IsOLI(jilt i eI
Itho loading edge, tile priessures dsrt to tanlgle 01' 11; a;1
pi'eno'.l mit-1t lu'O itigh anges of attatcI mid 0i i s if -Is thle !'lrestriittu-Ra design conditions. Design presstitres ovel, the First: fourito five percent of thle chord are thus independent of ocamber andbottom shape. A reduction in these pressures couild he ichieverl bysacrificing leading edge sharpness, hut this entails a loss in foil
V T/D and cavity inception characteristics. The leading, edge prof'ileshmouldr he maintatined as shar~p as st'uactuarall v% fetis.' in *
Fl[gure 56 qho-ws chite dwise ben~dilag sti'essse10 O il LIl H'aIMi p 1 ead-hI g odgi' c~ P a .f'n i operating at 12 degi'ees angl?,'e ol' aitV;nu' whinch
M0DE0-91. . THURSTON AIRCRAfT CORPORATION REPORT No.~i~SANFORD, MAINE DATE-
Pug 1
K. Efectof HvdIrofohil Leading Edge Angle in Supercavitating Flow
K. Continued) (p 2 s. I
sujects it to a loiading oU approximately "cl"
if reasonably small %.edge angles and therefore moixitrinir L/D'-i HP('
to lie realized. The l oading of 1q11 psf arnd oriiespouding angleof' nttac-k of about 12 t&Vgreaes are reasonable -~ahIi#-s for stiiictira Ldemign. This loadiiig ia-t an ultimate stres.-i oi .-i')t),CO0 psi req4izii'(.a t~ading edge wndfge a~iiji Of 3. 1 degrees 1't a ma N Im1rn.,xi N-lirespi~ed of 100 knots, and 6..' degrees for a iiitxinitii ."-Iilcli -4peeri of'20(1 knots..
L. Effect of Trail.ing Edge~ Flaps on Hy-dr'ofoii Pf-i'ioimaiii o
The L/D valties of' %vi~irioiie hydro foils dritgnjped for' super-ctvi tating flow tiv.' all %v'iv similair when plotted versllq iligie o fR t -t d ik. However, when pi itted versum L'I thue prnik valuito. of L/rn
0oirI II at dIif ferrlit. vt 1 11es ifCL dopending upori flio* bottom sliape
tI tht' Foil F (I I wedgeo" ii Il Fi lat bottom.-', tin tl~ If.,_111m1 /I 1'Mi'in '.;I' erv low C Aicitiii1'i inctouist?! and ;i- t l(-' Lottom ii ¼ape
1), ~ms more optiirmi'i, l'i !xtimple the .Tohns~~I ii teA I , thein., hiiiwi 1/n occtit-ý- ;it piingi-,,-iive1 htighier' \~., it L*o t Ito
1i lv ii o of the cuinbe r~ed design is that hig~h I I I't is obtirtiied atmaNi iniiim L,/D value-i. Such profiles would be tidlen I f'or- optimizingconlditionIS at the criticail point of hump speed anjtd unportli g, wheredIrag VIs 0; a peak. Their disadvantage, however, lies in thle factthat cnmt-t~red hydrofoils must be operated at angqlos of attack ofaboitt fiiii' degreer, nhov6 zero lift to obtain optimum L/D values.Thi.I. i natrrow range Is4 impractical for aircralft application sinceciimparitively large ti'im angles will he realized during hteave, pitch
*and unporting. As a result, the advantages of a sophisticated* foil suchi as the Juhnson aro diminishied, and tho wedge shape becomnes* mar' attractive. ThoE penalty paid for' using.the vedge is a smaller*va1lue of' C compared to the Johnson typo at eqjual valiies of L/1D.
A wedge can be iiado to perform ili ~i\tor n cambered foilli\v the iise of' a t.1-ail ing odge flap. 'In thii wFs , thle aid Vii tagesof' hot li foils crti hP realizo.d. For' a Supel ( v~i t::ting foil, ecper'i-mrrits hitve indicnotd that trailing edgec flanpsQ alj 'art effective way-of' maintaining lift at speeds below cruising. At a fixed foilIncidence angle, thre flap pfirmits lift to loe maini~tained at lower
* speeds and with less drag than would be possible by increasing thefoil incidence without the aid of the flap. Furthermore, itcombination of iricidence control. and flap dleflection provides evenhigher lift forces than with flap alone. On an aircraft, incidencecontrol is obtained timply through changing the pitch of the aircraft.
MODEL. THURSTON AIRCRAFT CORPORATION REPOif No. 69..~i2......COMT... S1ANUOND. MAINE DATE_______
UPA {
11. Lffect of T-rR nili a- ri-- i.pn- . I J4& 4 L itfilutinanc ;()fnlnle
Figure 57 (a) and (1,) prmvioe lift -nr! .! ,- ,u e'rielj l.1daota foi a naturally Veintli ted six degree we',l.e Ii, V1,ofor o .i tvIt 1a 25 percent chord trailing edge flap. As ,an bh geen, both I.i fr;and drag respond proportionaLly to flap deflectiom.
Bly progres!ting from the lower left to the tipper rT•ght of'the (CI,/CD versus. CT, plot, figure 58 (c) shows- thl-•t: the 11, 1) r - tov'an be improved with flap def'lection.
Figure .59 provides ditta for establishln•ii tlre minimum ang,'lesof atteck required to maintain a fully developed cavity in m.onthand 1(.TRou] water. This should assist in deteimrnriirif the lower1 limitof' •n ') e of attack.
While of Ititeretit Cor cruise range u'Ia ,i' v ellc*. Los ii ll ',,osemplanes, the addod structural and mechanicr.i complexity of flappedhydrofoils must be weighed a;painst their operat ,imi-il. •can,•.
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO, J..,CONT_ _ SANFORD, MAINE DATE
PUT 0.2
(DiroIalaAre AM 0*1w1i" I a0) ~.
Refeo Linwe M
CIxMjAR ARG .0*UO2 0 SIAP
Raf~aene Lue~
0. 1 A
PRefsteno. Lli -
0 0. 0.p.g.-05 06 . .
Ref wenee Uina
flGe 22 (a.
SUPERUMIATZING HT70F0L D0TTrh SWAES
?no strom dfreetion votneldee with Sef~amnh Am"e for' MC 0.
Ref I Griumman Rept. PB 1617M9 Fir. I1 I *
MODEL _________THURSTON AIRCRAFT CORPORATION REPORT NO. L..SAr NFOID, MAAINE DATE________
ICII II
: k
°,,
a'4
MODEL. THURSTON AIRCRAFT CORPORATION REPORT NO,
CONT SANFORD, MAINE DATE
PAN
TVPE OF PAOF16E CONDITION Of FLOW
SBuf feting i
r Vapor or Air Cavi ty)
2= Supetcayltating
S, t, (Fully Ventilated Cavity)
(Bose VetdCavity)
Fig. 22()-The Effect of Cavitaltion and Ventilation on the Hydrofoil Flow Pottern.
Ref: HycdrOItLI-LiCS fluch. Rept. 001-7 Pi 9. 1
MDLTHURSTON AIRCRAFT CORPORATION REPORT NO.CON?_________ 9ANFORD, M11AINIE DATE________
-FOIL CM!'hfACT~l?15TJC-5 FOR 5-iBCAV/IAi,'ONIL -6 WEDvCE (ItEF LINE LOI.JR SUFFrACE) - CAL.) N547.o O-TcCI.
------------------------ DTmB SERIES HF-I FOU - DAY TAYL M'OD. 045. ~RF'o /80/ P!- - - A 66,-012 -IOWA MNST, OF N"PR, RES. Rpr C0N'rN9omo.-9380 S
,..5
.8 .4 //
-1Z/
04 30 0020 3
/OSN A'V FOLL../
/22
AZ -
0 0010 01- e20 30 0 /0 01203
A ~ ~ Fig 23O
MODIL TURSTN ARCRAT CRPOATIO REORT o. Q41
CON- IINODMAIEDT
IImu~~PS qLAP rVI' Fi
If j lf % 1 " " .I."~ 0%0. .I 'j%
SUPERCA VITA TION6° WEDGE(IFF LINE LO4SER SJRFACE)- CAL. INST. OF TIECH.
RP 47-•/4. SEPT 194,0NACA 661.012 - IOWA INST. 0' PYDR, RES. RP" CONT. N9o,,r-53805
,2 JUL/Y 1961JOHNSON 5 T:RM 5UPE'CAV. FOIL 4, 00.)944 - NACA MEw.MO
5"-9-""L JUNEI2F9.
28 .4CL c.
, .3 e-
o Z•. - - - 0 - _ _ _ _ _ _ _ _ _ _
o0 1 20 30 0 1o 20 .3
MOMENT ABO'UT FOIL L, r. 14
. I 12
-.3 4"- • •L
-0 20 0 JO 20 30
MODE.L THURSTON AIRCRAFT CORPORATION REPORT NO. 6912CANT_____, ________SNFORD, MAINE DATE_________
PANl "•
Xomograph Snowing t•ie• ilationshin of Depth of 5uhmerg,,nce. Cavitation Index,
and Sn-eH of incipient Cavitation for any Body u7
TWO DIMENSIONAL 81
Refi Davidson Lab (SIT) Tech. Mem. 133 Fig. 8
10
ote; This chrrt applies to sea water at 55 F
-- 200 .
20 15S150 7o estimate th(, speed of incipient_ - 0
c,1v-tntion for a body, lay a -_ styallahtedge on the given h and
- c ; the r!sultant cav4.tation speed- 10-is the intercept on the, U scale 20
7 100 i 0
~- go I25
G .-
: u, i , U
I -, : ,4)."'~ .40•.
r .
40 40-
S/ ,- 0.30 30
',: /•--0.5 350. 0 o•- 0.4 0 "
-.-- -- 0.3 60
10 0.2
'-- 8o ---L0.70
L-- o0 Fig . 25 (a ) 0 1-0
100 -- "l
MODEl. THURSTON AIRCRAFT CORPORATION KEPORT NO. 6c12CONT?_ _ _ _IORE, MAINE DATE
_ _ _ _ _ _ PAN _
2.0
1.6
1.A4
0
Wu 0.6
0,4
040 60 80 /00 120
kV(q7ER TE ipr7plvFtc1 ,'
Fig. 25 (b)
H.ef: Grummatn Rept. PB 161759 Fig. 1.8
MOILTHURSTON AIRCRAFT CORPORATION REsPORT mo. 6 1GONT__________ SAFORD, MAINEI DATE ________
IIPAGE.~ .
NACA 66.O02I
/ , 4
' iT! ipE I~R ACE L I I tAK oANGLE 01 TC. .0
04*
i / ; " ,, ,'
0C 04 14 II o0 m
CAVITATION NUMOER,
Fig. 26 - .ift coefficient as a function of cavitation number atconstant. angle of attack for t1" NACA 66 -012 hydrofoil.Each an-Ie of attack represci-ts one test run.
NACA 661 " 012
I I I-- ..
1?_ 0 _ I
0 0 -- --
o TA... .,.
0 04 tA o I 30 14 asCAVI TATION NUM,• E R
Fig.27- L u.,- cz, . -l2cient as a function of cavitation nunber at constantS- '.' r ,NACA 6 1-012 hydrofoil. Each angle of
~~on,; zkb run.
S Ref?. Cal Tech Rett. 47-7 Firs. 7 and R
MODEL THURSTON AIRCRAFT CORPORATION IEPORT NO. 69 12iNT IUlUl, MNAIN DATE
ANGk5. 0,F ATTACK, 6 a
77.
77..
I..
1~104
NACA 661 012
o"2/ aIac -o h-A6 02hdool
C~VIMAVPT$6UMBR. ION
CONr________ 0MOI, MAINE ...DATE
II6 degree wedgej
J , ,1 . ., 1. 5
.6.
-44-
J'j .4-•.' ,- ...• . - o "-
at Costn _______ ofAttack,_AR = 4.0p .3 : Cal Teh/p 71,Fg n
7•,---------. .. .-
. O, T U O CAVITATION N COMBrRP R I .O NO. 6. 3 I .
Fig. 29 Lift Cs,2fticiont an a Function of Cavitation NuAberat Constant Angle of Attack, AR = 4. 0.
t•i
.. .. " .. -" .
.~, - 4,
-o -.. . -'. ~ <
" LL -, I ,1 .". •s , I • .0
Fig. 10 Zo'ag Coefficient as a Function of Cavitation Numnberat Gonstant An~gu of Attack, AR• = 4.0.
_ ,,, R,.hf': Cal Tech Rept /47-hi! Fig.' 8 and 9 ,,
MODEL ______'___ HURSTON AIRCRAFT CORPORATION REPORT NO. 691CONY - - ANFORDO, MAINE DATE-
O, CAVit O NUMIJ•. ... __ _, _. .___ 9 ,0 1. 14 .
,,, • -, _. ... _ .... -.. .. ._.,__-.• :
-. "-i'---...--/---•" --' --'- .- ... - "-"--
S-.5"'
- -- --- -
-,6,
Fig. 31 Moment Coefficient as a Function of Cavitation Numberat Constant Angle of Attack, AR 4. 0.
Moenent about foil leading edge.
* 6 degree wedg ,
2'W FC.. ATAC49k I r
I *-~I0 .0 . . . . ' •.-. .9 ..•I,'1.0 1.1 :2 . , - '
C, CA V ITA TIO N NU M BER
.I . 1? Lift-Lrag Ratio as a Function of Cavitation Numberat Constant Angle of Attack, AR = 4. 0.
R c V: Ca 1 rech Rept b17-121 Fig. 10 find 11
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 6012CONT _ANFORO, MAINE DATE
}I,
deg"e•P wedge
----
, ... ....
u .4 Ap
." , ' ,; " "'\n 'o .
CAVITATION NUMBER
Fig. '3 Lift Coef:'cient as a Function of Cavitation Numberat Constant Angle of Attack, AR = Z. 0.
6 degree wedge
r
.3 ff. CAIATO Ne, :
at Contan Ang, 'of Atak AR =. ,.0
'.7/" -- ,"
., .• ,,8,1 ,1 , 9 IO ,I ,,2 I.' I4 if
•-, CtAVIIATION N7lUM{I*4
Fig. 34i Drag Coerficient as a Function of Cavitation Nunmberat Constant Angle of Attack, R :. 0.O
L1~ ~ ~ ~ ' ResClTc et 47-1~4 Fg 2ad1
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO, WJ 12-CONT IANFORD, MAINE DATE
I
4. o 1._ __...0 1 I IS i4
" - .. .-
V..
i '
-~ _______ wedge
Fig$ . Moa~ent C,-ificient as a Function of Cavitation Numberat Constant Angle of Attack, AP = 2. 0.
Moment about Coil leadli.n, edge.
6 degreo wedge'ROL
O, ANGLE
COW MAN DE
i0 o i**
, ' Q,0,.
' " -•"T '. - -.----.--- -----.--....{• I ... - .. .. " " .. . < • • " ' " -" . .. . . ". . .. • •--. -
CIm-
GV• TOVI•, rOIV UM,. ON
V,'I. '36 Z.it-Drag L;tio as a Function of Cavitation Nun'berat Consta~nt Angle oi Attack, AR 2. .0
flef: Cal Tech Rept 47Z-IJI Fig. 12# atnd 15 I
MODEL THURSTON AIRCRAFT CORPORATION RlPO1RT NO. •..CONIT. SANFORD, MAINE DATE-
iI
6 degree wedge .,o
' Ii .-..,--• '4 . .- .
.•
CA ATO N B A
at Costn . l f Aa A
,. 6 .. ,,.- - w 1-. Id.,CAV A1.ON NU/. . .
Ligt Co,,iciont as a Function of Cavitation Numbe r
at Constant A-,-yi'L of Attack, AR =1. 0.
II
MODEL, THURSTON AIRCRAFT CORPORATION REPORT NO.
0091? SANFORD, MAINE DATE_________
a Costn Angle of Atak An
I
. 5 ..•, N .. . . . I I•,/ ,.
6 Ir,(,d . t-'re wedge
Fig. '9 X:orent CoPfaicient as a Function of Cavitation Numberat Constant Angle of Attack, AR = 1. 0.
P f (r Icr1 IoP t )47- 114 leFi 18 a et "'.
+i ~6 degi'•'t wf.dge
MOE THRSO AICAT OPRAIN * EOt N.6
CO. I M _.N
S- ----- i-' --- -
J - 6 ' 9 F0 II 5 ' 14 1.5
,, A•/,tA+,,J3 INu8EP[
Fi•0 11) 9 L-r, R tio as a Function of Cavitation NumberatCo.,-;cant Anl of Attack. AR = 1.0O.
fief' C:I ITech1 Pept J47 -11 'iVA . 18 n•nd 19
MODE., _________'hURSTON AIRCRAFT CORPORATION REPORT NO. -- 69 1 "2...--.
CoN?____________ AFoRD, MAwIE DA.TE_________
WEIT1 I i p.. _1 V %o-rr
-7- 7
fe t
-~~ I
I IK: ~ I:2T
K~*~ -A
SIOS O7
rig. 41
Ref: Grumman Rept. PB 161759 Fig.i.4
MODE________ THURSTON AIRCRAFT COOPORMlON PtEPORtT No. 6912iL.....K- M~~&IUIDII MAINE DATE________
U PAN
K" " atzK
*L, L. Li
* it:,.. it
THURM PCRM ONDTMN (11
PAIIIIEffect of Depth of' Submergence on
-Supercavitating Hydrofoil Performanice
IND
0 '
.2016
xy V Vv
C, .2 .4 .6 .8 1.0 0, A2. .6 .6 1.0
(b)b FlatI.
:il~ (11'r~i'ivjt.SCOni.,. ;.:")]I or
Fig. 243
Reft NASA Tech. Rept. R-93 Fig. h6 and 50
MODEL _________ THURSTON AIRCRAFT CORPORATION REPORT NO, 69ý
CON?_________ SANFORD, MAINE DATE _______
4 4)
PE 44
4- ...44'
V 4
IV 0 0
1 -W
0 0 0
0 0 ..
04 C)U.) ýt
[ ] "• • I i ._II
CONT UNFORD, MAINE DATE
S.. . . . . .. ....
J 4S
om i U) 0
41)
I eet
I 0
W Q)
MODI THRSTO AICRA"CORORATON EPOR NO.7'T &kN.D 0AN DATE
A'1I J
V1 s
711
i~Ii
j I ..
-,.
L THURSTON-. -.RCRA- C 6
U -M . .. D T E.
q • -- j--- ,, ,.
--, I .i i--- *.
S.... i N IN I I n II l UU l I u l I
coeI... Aam au t I A'
; .: /' •
,'-/ li'
K( 0
"- / -' /,
co", UHOD MANI DLJ
• 11.1
iZ1 • ,..
/ J °-
C" .... I , " -UT)•
00
I I C.I• 0
"•-' - -- . .. . . . . '"--. . .. •' r'-I
1 1.. _.... L.. ' -- ' 11.. ,-i ;,C•*J.• C)
NODEL., THUIRSTON AIRCRAFTr CORPORATION REPORT NO.- 1j1COW? SANFORDg, MAINE be! ____"____
_________ ________________________________________________
141I , I 9.'
, i -
I• /
0 3
S I '0 "
C / ,•• H .,
I I I H'
I Ho 0
0 H In-
- I, / °'C)
oo
zII l I
:" I 1/ ',
to v "44
- II• U I I
I4I
S MODEL. THURSITON AIRCURL' CORPORATION REPORT NO. 69 12
f CORY SANFIORD,~ MIAINE DATE
S. ... • • j i " i ... ... • . i . . . " " i .. . . .. . ...i . . . . ii ' . . .. . . . . i . .. - - - .. . . . . -L " . . . . .. . . . . ... .i . . . ... . i . . . .
Ref: NACA RY L52J1.O
j ~2050 1lo/rt"Oboorvod
jcavitation~
L IGC.
-10
.4I
0 10 2 3 Z0 40 50 60 70 GO 0Speod, V, fpa
Fig. 48 (,1) Li :' coclý'iciont.
- \'r~aicnWýthl 51peCd 01' J13hroV0tyna~ni.c! charnoteri~jti cs0,' 0-4-0.6 hydrofo-1l.
MOhh2. THURSTON AIRCRAFT CORPORATION REPORT NO. 9CON?______ _ SANFORD, MAINE DATE______
77 1" i!
4--,•,,80 I " \ - - ---- - - - - - - - -....
. 1,o
_ _........ I _
. . ., I I
,Spood, V, fpa
Fig' 4 8(b) Drag coefficient.
MODEL THURSTON AIRCRAFT CORPORATION nEPORT Nwr q 1_o_ _UAFOR o, MAINE DATE
!51L So
I
: L . I -I Ii {
' _ ".Fig . -8
,'.0 Ob-arvod cavitato itcn .,
[ ,5 r - I_ - -
" ~ ~I I I rt I~
II I I- II-II-I*I
MODEL. THURSTON AIRCRAFTl CORPORATION REPORT 0O10. ;PONT WJll*, MAINE DATE
Refs NACA R: 152JI0
1..0i
.'.5 '1 .0 0
2.0/-; - • -?I L'' I 1 J I 8
I i ,I
.0, k _-_- _-. - _ _
c'•l .6 , 0 • ,
. iI I°•-71.•7--' '_
3. - j - I
: F---- -- 1 --- _--.,--,_
F-I-- --Ij---o I
Q 20 30 40 50 60 70 80 v0Spoed, V, fps
Fig.49 (a) Lift coefficient.
- Variation with speed of hydrodynazic characteristicsof 4.-4-0.6 hydrofoil.
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 691 1CONT SANFORD MAINE DATEI _
PAU 53
,Ref8 i
I 1•.7 L52J C
' t o- -'7- ... . .
.24 y---T----. 7 - -0
.- A.1_ 14o, N
•120
S.12
l -o
20,- - -
0 , -
10 20 3 0 '0 so 60 s0 0 OSpood, V, fps
Fig. 49 (b) Dfra c¢Ifficient.
MODE._THURSTON AIRCRAFT CORPORATION mrPoRT NO. 6-1tO.T &ANRD, MAINE DATE
iI
eft ~NACA RM L52JIO
' iI ,_ ___ '
__ I I ii I I. __
3.2 , 2
S[ I /
a oviotaton-
o0eogL) 10 20 30 40 50 60 70 80 90
Speod, V, fps
Fig,. 49 (c) Lift-drag ratio.
MODEL THURSTON AIRCRAFT CORPORATION REPOnT NO. 69 12
CORY&OwrNUOng, MAINE DATE
Reof
o107
P 200
.1- 7 21
0 10 20 30 40 50 60 70 80 90Speed, V, fps
Fig. 50 (a) Lif~t coeffricient.
-Variation with speed of hydrodynamic charaicteristicsof' 60-4-0.6 hydrof~oil.
MODEL________ THURSTON AIRCRAFT CORPORATION RtEPORT No. 6912J....COUT_______ SANFORD, MAINE DATE _____
II
IapuodI--i----' --: -I -
_ 1 ,.. . . .. . I-
.L - . - . ......
.24
.0:5 '0 K
20
0 10 20 30 40 50 60 70 80 90
Spood, V, £fs
Fig. 50 (b) Drag coefficient.
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO. 69 12CONT""popANPO, MAINE DATE
:;:ACA .. L,52j1Vj
10 1iICL~
100
---- 2
0E-10 20 350 40 80 60 70 Go~ ?5pood, V, fps
Fig. 50(c) Lift-draG ratio.
moon. THURSTON AIMRMRF CORPORATION -6OT OCONT__________ nE~m MAMINEMN DATE
Refa t ACA RM L52J10
loadin~ I
IT 13CC lb/r 2
1.0~
.7
.6
(.4
T- L
.2
0100 .. ..
0 2.0 20 30 ".0 b0 60 70 so goSveeci, V, fps
Fig. 51 (a) Lift coef'ficient.
-VcariaLion with speed of~ hydrodynamic characteristicsof 45-4-0.3 hydrofoil.
MODEL________ THURSTON AIRCRAFT CORPORATION NgpON? No. 6912______________ gupou M~INE DA72________
I
Ref
I IM
, . ../11I I
-. .. .- :., -_ -A--1-, ...- :i I -• J ]
o ,+ --- '--1 "j . .... . -i' .. ..... , -..
-. 7 t'" ', "--Z1
.36O
. .. ,,---- -- ,-- -..-
--- -,--- __ -
° I
°° h ZI ],• - , -- ] - - - - - -.02 2()o
IOU
I 1 00
.0 10 6(l 3 40 bo 00 70 00 90Speed, V, fps
Fig. 51)(b) flratr coef'ficient.
MODIL _ _ THURSTON AIRCRAFT CORPORATION REPORT NO. 69 1cOla __NMI D, MlAINE DATE .. ..
II
Reft NACA PM L51-10
I~
:~'10 - -bse.vcd cavitation-
-...-------- '- -•
0 10 2o 70 C o
spooI, V, p
F1 51 (c) Lift-drag ratio.
monO ________ THURSTON AIRCRAFT CORPORATION EUPO~r No. 6-91..GOUT__________uwn MOINK DAME________
PM1
Ref s
J J
U IU
I J, 1,'T
c~.i, I ~ %
, C F'2 1 I 'I
___I. 'Ped - -r~~vmom~~~~ ~~~~ THRTNMUM OPOAO tpw o
-ON W0-,- AKDT
IIPN 62
Refa"7ACA 1. LT.,2JI0
II
L_ 60-4-0.8
w' ______________"__,
0 '--- . .4 .6 , .Lift coeffCiciet, 0 L
(a) Speed, 30 feet per second.
i6-~
12 ' 4.r,'0.
600-4-0.64. ,
12 - 45-4-0.6
Speed, 60 feet per second.
Fig. 53 Effect of sweep on lift-draG ratio.
0 II
NOEl- THURSTON AIRCRAFT CORPORATION REPORT NO. .....6,uONT II iE DATE
I
Re f I'ACA IRM L52J10
6 16
1 45-4-0.3
12 I
0 I I I
0 .2 .4 .6 .8 1.0Lift aonfficýrt, CL
(a) Speed, V, 30 feet per second.
16 I
0- ,I .. .I I
0 .2 .4 .6 .8 1.0
Speed, V, 60 feet per second.
Fig. 54- Effect of taper on lift-draG ratio.
MOD. . THURSTON AIRCRAFT CORPORATION WPORT NO. ,ONT SIUSOD, MAINE DATE
LIIILIFT CHARACTERISTICS
0.60 m_
0.50 I
FULLY ATTACHED
(BASZ VENTED)
3.30 '
S 0.20
4.) FULLY VENTILATED
0I0.10LO
2 I-0.20 t
-0.20 ____
*I
I-I
0 2 4 6 8 10 12 14
XCOS r (DEG) r=dihedral angle
Fig. 55 (a)Ref: Davidson Lab (SIT) Rept 952 Fig. 2
moon THURSTON AIRCRAFT CORPORATION REPORT NO. 6912CONT ?_Oh1, MAINE DATE
PIIAN
DRAG CHARACTERISTICS (FULLY VENTILATED)
0.08
0.07 i-
0.06i o
0 .0 5 -
_
C Cos C0S ./
0.04
0
6.03 -_ _ _ _
0.02 __ __0_ _ _
0 1i
0 .01 0.02 0.03 0.04 0.00 006 0.07
LC SIN O
Fig. 5ý5 (b)
Reft Davidson Lab (SIT) Rept. 952 Fig. '3
MOM. THURSTON AIRCRAFT CORPORATION REPORT NO. 69 1 2
CONT__ANFORD, MAINE DATE
L0 IN L~di
L.L P E J.
V- c om or D-44 Ob f
* I 2Si--. N~3
ReT: Grman Rpt B 1679 i. 1
M o u r n . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _( X ~ t a T H R T N N C A T C R P R T O Ex OlOUT ____ ____ ____ ___ A77
0.1 0.2 -
0~0.1
6 a 10 12 14 is is 6 6 10 12 14 16 1
0.61
6 a 0 12 i4 16 is6 8 10 12 14 16 18a a
~ Velocity
0.6 -20-0 12 fpsA 14 fpsD 16 fps
C L .5 I8 tfps
0.41 6 degree wedge naturally ventedal foil submergence
0.3, 1 1flap = 25% chord T.E. flap
Fig. 5 7 (i;)Vorlation of Steady Lift Coefficient with Angle of Attack, AR =1,l/
Ref: U. of Minnesota St. Anthony Falls Rept 68, Fig. 2
MODEL THURITON AIRCRtAFT CORPORATION REpoRT No, 6 912CON?________ SAPID, MAINE DATE_______
PAlE 68
0.60.4 - ~I
0.12 0003 82
0,00
6 8 10 12 14 16 183 6 8 I0 12 14 16 Isa
~aI2O
CO 0.2 C0 .
0,6 a 10 12 .'j 16 Is 6 -8 10 12 14 16 Is
20 - 7 Velocity *0 12 fps
C3 16fps0 Is fps
6degree wedge naturally vented
07 a = foil submergence6 8 10 12 14 1618s flap a 25% chord T.Eo flap
Fig 57 (b r-Variction of Steady Drag Coefficient with Angle of Amtick, AR = 2, d/c =I
Ref: U. of Minnesota St. Anthony Falls Rapt. 68 Fig. 3
UOU. THURSTON AIRCRAFT CORPORATION MEPORT No. 6
C~l___________AIIOI, MNEPATE______
PA - N
Mo Q
0I- I I4
0 I N a-
°°---- - ,-o _s 0"
Cr,
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6 degree wedge naturally ventedd-foil submergence
flap =25% chord T.E. flap
MOLTHURSTON AIRCRAFT CORPORATION REPORT NO, ~CONT_________ sLuwm, MAINE DATE________
I-0I
a min. mil
4-- 4
20 0.5 Lo 15 2.0 2.5 0 0.5 1.0 1.5 LO0 2.5
12 12 1
min.n
4
W Id
16 0 12fps
_______ 14_ f ps
0 min. 0 is fps
Solid symbols ore data takenIn waves, others in smooth water
a x 0.1 ft____X a 3 ft
o 0.5 1.0 1.5 2.0 2.5 6 degree wedge naturally vented41 = foil submergence
flap = 25% chord T.E. flap
Fig. 59 - Minimum Angle of Attack Required to Maintain a Fully Developed Cavity inSmooth and Rough Water
moonTHURSTON MECGRAff CORPORATION REPronR No.691
CONT________ WWORU, &KINK DATE______
lj itPAR 7I
LVO. Strui Conziguration Data
A. Design factors affecting strut selection
Selection of a strut to support the airplane on the hydrofoilwill depend upon the rollowing factors:
1. Airpiane gross weight2. Aerodynamic lift curve3. Take off thrust4. Hydrodynamic drag of entire airplane including estimated
foil system drag5. Hump and lift off speeds6. Lift and drag characteristics of foil for all operating
conditions7. Type of hydrofoil system
The strut must be designed to achieve structural soundnesswithin acceptable performance boundaries. The main considerationsfor strut design are: low side forces, low drag, provision forventing the hydrofoil, adequate structural rigidity, and resistanceto flutter.
B. Drag
Drag is most critical in the region of hump speed, wherethe unporting phase of take off begins. If sufficient excess thrustexists at hump speed to provide necessary longitudinal acceleration,strut drag requirements will be reduced in importance.
C. Side Forces'
Strut side for4es must be kept as low as possible to minimizehighly undesirable aircraft rolling and yawing moments. For thisreason, struts should e made from hydrofoil profile shapes thatdevelop as little lift as possible. The most effective configura-tion is a supercavitatlng strut having a relatively large leadingedge wedge angle, flat sides with relatively high thickness ratio,and a blunt trailing edge. The blunt trailing edge provides earlyseparation and a path for ventilating air 3to the foil. Therelatively blunt leading edge induces early cavitation and a cavitywide enough to completely surround the strut. Any yawing of thestrut should then provide strut clearance from the cavity boundry.Under these conditions, the side loads on the strut are minimal.The actual configuration must take drag into consideration, whilethe final design will be a compromise between drag, side forces,and structural rigidity.
MODE. THUISTON AIRCRAFT CORPORATION REPORT NO. 6tow.., _Wo_ MA"NE DATE
I
I ID. Typical Strut Cross-Section Shapes
Figure 60 shows two typical struts; one a streamlinedsubcavitating shape with a blunt trailing edge and the other arectangular supercavitating cross-section with a wedge leadingedge.
E. Subcavitating Struts
Figures 61 through 67 apply to struts that are fully wetted,is. cavitation is absent. They provide a breakdown of the variousdrag components and spray height. This data permits calculationof the total strut drag and the spray height for a non-yawedcondition. Side force can be approximated by using the subcavita-ting lift data for the DTMB series HF-i foil from Figure 23 forthe appropriate aspect ratio.
The drag of a subcavitating strut can be divided intoprofile drag, wave drag and spray drag:
1. Profile Drag; Applies to a section in two dimensionalflow and is the total drag for fully submerged struts(pre-hiump speed). This term is the sum of shear andviscous pressure forces.
2. Wave Drag and Spray Drag; For surface piercing struts(post-hump), wave and spray drng are two additionalsurface effect drag terms.
Figure 61 presents the profile drag for three NACA airfoils(with varying thickness and size) plus one ogive section, versusReynolds Number. A comparison is also made with the skin frictiondrag of a flat plate surface. Figure 62 shows the ogive strut datain more detail. Figure 63 provides wave drag versus Froude Number,and shows this factor becomes insignificant at higher speeds (forexample, above approximately 20 feet per second for a strut witha one foot chord). Figure 64 presents spray drag data for strutsof varying thickness ratios. Figure 65 is a plot of the residualdrag for a typical strut, defined as the total drag minus theprofile drag; or in other terms, the spray drag plus the wave drag.
For speeds greater than 20 feet per second, where the wavedrag diminishes, the residual drag is approximately equal to thespray drag. This is the region of interest for a seaplane, sinceunporting will occur at speeds above 20 feet per second. Figure 66shows the direct influence of thickness ratio on profile drag, whileFigure 67 provides spray height information versus speed.
MO-._ THURSTON AIRCRAFT CORPORATION smpon" No. 69 12GONT _ _11M MANE DATE'
I - IF. Supercavitatinor Struts
For supercavitating struts, Figure 68 presents drag coeffici-
ents for varying leading edge anglesl the leading edge of the wedgeis the only portion of the strut in contact with the water. Thecavity left behind provides the boundary wall which limits the sizeof the strut. Any size or shape strut can be introduced inside thecavity without affecting the drag or side force. Figure 69 pro-vides the cavity width, while Figure 70 presents cavity lengthinformation. The effect of strut yaw (with the strut remaininginside the cavity boundry) must be considered when selecting lead-ing edge angle.
With this data, it is possible to select a strut configitra-tion providing the desired performance and structural strength.This is a preliminary step toward testing the system for furtherrefinement.
MODi. THURiTON AIRCRAFT CORPORATION REPORT NO. rCONT "WNFM% RMANE DATE
Subcavitating Strut
Rel'4 Thlurston Aircraft Corp. Strut No.2
TAC Report No. 6702-3 Feb 1967 Fig- I
Supereavitat.'ng Strut
Fig. 6o
OML THURSTON AIRCRA4T CORPORATION WOW N
CONT SANMOR, MANE DATE
F ..i = • --- -• -• . .
(.JPAN 7
STRUT PROFILE DRGcowTicIu
7-'
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Ref Daido La (SIT - R-59 Fig.2
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VARIATION O THEORETICAL WAVE DRAG COEFICIENTAT HIGH MJDE NUMBJ N FOR SLENDER STMUTS HAVING
S0.60
C.)0.50
0.40 -S0 .
0.35
0.30
0.25
S0.20
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S0.0%
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= 32.2 foot/seo
Fig. 63
Ref: Davidson Lab (SIT) Rept R-596 Fig. 1
MOO_ _ _ THURSTON AIRCRAFT CORPORATION REPoRT NO. 9GON SANFORD, MAINE DATE
flSTL'_S UT' GRAF1ICAL DLT1U•IMA2OnSCl? SPRAY MOAC YnnM VARIAUR S
2.0 Reference: Kaplan P., Stevens Inst. of Tecim.Letter Report No. LR- 1188, 1953
andDavidson Lab (SIT) Rept R-596 Fig. 4
S1.6S. ~Thee retic cIS~Wave Rcsistarce6Symbols Thclaiess Ratio
a ETT .12E-, 4 0 2 -B .2 5a 1B4ACA .12o Cr)STANZI .25
1.2 .1 8TT
I;Ar .12
+ 1%+NACA .120
x IiAGA .21o -I . I C 'o .0 0NACA .13
y ETT 615A ETT
0.8 J ID A\
"0.2 -
-.2 -ý- or- -Y - . ," .
l i • I~~~~.. 0 lI . . .I.. . . . . .
- 10 20 30 11o 5o 60 70 30Spoed-Length Ratio, V.4/rc
Fig. 64
MODIL THURSTON AIRCRAll CORPORATION REPOnr No. 6 c) 12cOiT_ _ __ANPORh, MAINE DATE
7QI
LLI j04 i
1-41
Lul-J . 4
~LV~ Lz
-LAL N .D1
£7N KAPMMN DATE:
PAU 80
4 .012
NACA 1 Digit Series~.008
-1 NACA 65 Series (Smooth)
.0 .08 .12 .16 .20 .24
Thicknoess astio t,/a
Fig. 66
PROFILE DRAG OF TWO SECTIONS AS A FUNCTIONOF THICKNESS RATIO
Reft Davidson Lab (SIT) Rept. R-596 Fig. 3
andTheory of Wing Sections, Abbott and DoenhoffMcGraw Hill 1949, pp. 152-3
MODEL THURSTON AIRCRAFT CORPORATION REPORT No. 26912SORT __AN__ _IFO, MAINS DATE
al
0
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moonL THURSTON AIRCRAFT CORPORATION IMPORT NO, 6 912-...CONY_______ MW"oD MANE DATE ______
6ý0M DOAG C~FP
FOX .5TP.UT W1774 VARIOUS LEAD)ANG FP&r ANGLES
TWO J'WMENSIONAIL
K0.4TWME PttAEN5ScO!RL
'*1
U Vm~Pes
20 40 to 80 too /20 )140 160 /do
APEX HALFP 4NGLF; 06
Fig. 68
Ref i Cal Tech Rapt No. 47- 4 Fig. 15
MODL ThiURSTON AIRCRAFT CORPORATION REsPORT NO. 6.a) j....CONY____________ SANOD, MAINE DATE______
MEI
4k
00
0.05' Jo 2%
CAVITAh, n N Alum ar, PO' P
Fig. 69
Ref' Cal Tech Flept No. 47-4 Fig. 16
MO THURSTON AIRCRAFT CORPORATION RtEpoiT 40, 6912SANr FORD, MAINI DATI
L.LK4
77#
.I do .5.2 .2 .3
Re s Ca.ehRp .N .4 - i -1
MORLTHRSONAICAF CRPRAIO MPRTNO gL2Z
COT NFR40M' DT
SPA'. 85
V. Full Scale Hydrofoil Test hesults
A. U.S. Navy JRF-SG Vqiippad with Grunberg SupercavitatingHydrofoil System
Under U.S. Navy sponsorship, during 1957 to 1963, the EdoCorporation designed, installed and flight tested a Grunberg super-cavitating hydrofoil system on a JRF-5G (Grumman Goose) amphibian.Subsequently during 1963 and 1964 this airplane configuration wasfurther tested and evaluated by the U.S. Novy at the Naval Air TestCenter, Patuxent River, Maryland. Front and side views of theinstallation are given in Figure 3. This installation used thelargest supercavitating hydrofoil built at that time and was thefirst application of a supercavitating hydrofoil to an airplane.References 42, 43 and 44 cover the work done by Edo, while reference139 reports on the flight test evaluation performed by the Navy.
The Grunberg supercavitating hydrofoil system used on theJRV-5G was developed jointly by the Office of Naval Research,National Aeronautics and Space Administration and the Bureau ofNaval Weapons. The system consists of a Tulin supercavltntingsurface-piercing hydrofoil (Cl=O.2) near the airplane cg and twoplaning bow skids, Figures 3 and 71. The bow skids were incorpatedfor the dual purposes of' properly trimming thp airplane duringunporting and to prevent the airplane from diving in case of hydro-foil failure. For an operational installation, the hydrofoil wouldbe located slightly further forward with the bow skids eliminated.
The hydrofoil was constructed of AIST 416 stainless steelheat treated to 150,000 psi tensile strength. For the purpose ofproviding corrosion and erosion resistance, a hard electro-platednickel coating was applied .003 inches thick over the entire foil.
The test airplane was instrumented with a photopanel,oscillograph, and flight test boom. Water speed data were derivedfrom airspeed recordings and wind information taken by an outsideobserver. The hydrofoil and skid struts were equipped with straingauges to measure water impact loads.
The bow skids and hydrofoil could be raised and loweredhydraulically to permit operation on land or water. 1,and operationwas limited to taxiing performed with the skids and foil raised.The main landing gear oleos were extended and stiffened to provideadequate ground clearance. Water entry was gailned by taxiing downE ramp: once waterborne, the skids and foil were lowered and locked.The skids and foil remained down and locked for all water take offsand landings, as well as all, flight work. Raising the bow skids Inflight would make the airplane pitch up uncontrollably. The hydro-foil could be raised in flight and would permit an emergency runwaylanding on the stiffened landing gear in a three point attitude(to provide a ground clearance of the lowered bow skids).
THURSTON AIRCRAFT CORPORATION RuPoRT No.61
IONS &UMR, MAINS DATE__
IIPAUE
A. PT.ý. Navy JRF-5G Equipped with Grunberg SupercavitdtingHvdrofoil qvxtam ( r rn- in- Ae
The take off maneuver was difficult to accomplish due to
marginal excese thrust plus marginal stability and control existingduring unporting. This, of course, wa- the resoii of the airplaneznot being specifically designed for hydrofoil operation coupled
system. The bow skids created considerable spray when approaching
and during hump speed, necessitating complete depondence upon theflight instruments for control of the airplane. Airborne, theairplane was nearly neutrally stable, both longitudinally andd'rectionally, due to the large bow skids and supporting strut area.L.anding technique was similar to that of a conventional seaplaneand was different only because of the marginal stability of theairplane exhibited during approach.
In the hydrofoil planing condition, the pitch attitude ofthe airplane could be varied from the lower limit, where the bowskids contacted the water, to the upper limit., determined at lowspeeds by elevator control. limit and at high speeds by bouncing ora heaving motion of' the airplane. Figure 72 shows trim angle data,plotted against speed and the upper boundary for bounce-free operation.Bouncing occured on nearly all landings regardless of the airspeed,rate of descent and wave height. Under calm water conditions, thebouncing could be prevented by keeping sink rate and airspeed to aminimum at touch down and immediately decreasing the pitch attitudeafter touch down to below the bounce boundary.
When planing on the hydrofoil, the JTRF-5G tended to divergeslowly from a selected heading and diverge rapidly from a selectedbank angle. These tendencies, coupled with weak directional andlateral control effectiveness at the low speed end of the planingphape, required many large, rapid aileron and rudder control inputs.Both directional and lateral control power improved from barelysufficient at low speeds to satisfactory at take off speed.
The power required to plane on the hydrofoil decreased froman estimated maximum of 760 BHP at hump speed (21 knots water speed)to a minimum of 400 BHP in the 40 to 45 knot range. This data wasdetermined during stabilized speed runs shown in Figure 73. Beyondthis speed, the power required gradually increased to 560 BlIP at70 knots. Figure 74 shows photographs of the JRF-5G planing atvarious stabilized speeds, including side views of the accompanyingspray patterns. Figure 75 shows the longitudinal acceleration of
the airplane at various power settings. The hump speed is clearlydefined at about 21 mph waterspeed, with minimum drag at 40 mph;corresponding to the minimum drag point shown in Figure 73.
Time histories of a take off and landing are given inFigures 76 and 77. It can be clearly seen that below 30 knotslarge rudder and aileron inputs are required to control the airplane.
Figure 78 presents impact normal acceleration at the
0omu THURSTON AIRCRAFT CORPORATION RIPOrT NO. 612, •NI' UI•IO00i• MANIN DATE
A. U.S. Navy JRF-i G Equipped with Grunberg SupernavitatingHydroio:L. :ýys:om (continued)
airplane cg versus sink rate. Data are also presented in reference131 for the foil loads versus sink speed. Tn both cases, therelation of load and acceleration is linear with sink speed.
Figure 79 shows the variation of elevator, position, trimanple, bow skid bending stress and hydrofoil main strut compressionloaf! with waterspeed.
Bi. HRV-1 (LA-4A) Equipped with Thurston Aircraft CorporationSupercavitating Hydrofoil
Under U.S. Navy contracts, the Thurston Aircraft Corporationdesigned, installed and flight tested during 1966 to 1968 a singlesupercavitating, surface-piercing hydrfoil on a Skimmer L.A-4Aamphibian, page i, This airplane was designated Ifydro ResearchVehicle (}{RV-1), and was the same aircraft used for previous hy-lro-dvnnmic flight test work with hydro-skis. This installation wasflit first applicatIon of' a single supercavitating hydrofoil on anai ',1lane. References 128, 129 and 130 cover the hydrofoil test workpet lormed during thi:i program.
The IIPV-1 hydrofoil was a 6.25 degree wdt-e with a 30 degreeleaiding edge angle and a flow breakaway groove 1/21 inch behind the1 er npg ,dge on the uipper surface, Figure 80, and was cast from
,,-T' 1 aluminum alloy. The projected planrorm iten of 1Mt) squaieinches satisfied both the desired foil loading speed requirementand the scale/weight relationship compared to a proposed Ti11-16installation. Figure 81 shows a profile view of the HRV-1 withthe hydrofoil extended to its maximum of 22 inches. The strui wasa subcavitating streamlined shape with a blunt trailing edge,Figture 60. Two close-up photographs of the foil and strut installedon the IIRV-1 are shown in Figure 82.
The test airplane was instrumented with an oscillographrecording strut loads, hull pressures,pitch angles and cgacceleration.Rrl',.rence 129 shows the restults of tests with the strut located at1ý11I stnl ion 79, while refe,'ronce 130 shows the resul t., with thestrut ot. station 96.25; ther-, was located at hull slatLon 106 for,both strut locations.
A comparison of data for the hydrol'ol | I xrSUs Ilit( airplanebasic hull showed the hydrofoil reduced the hull l,,,ttom pIýssures byabout 15 percent and the normal acceleration factor by abouýt 7,0 percentin calm water. Under conditions of one and one half to two'fbotwaves, the hull pressures were reduced by about 50 percent and theacceleration again by about 70 percent, as discussed in Chapter VI.Hydrofoil take off times were reduced by approximately 30 percentcompared to the basic hull performance figures.
I____________ ___ __ __I_
MODEL__ THURSTON AIRCRAFT CORPORATION RIPORT NO. 69 12CON SANFORD, MAINE DATE
IPAN .8L
B. HRV-1I (LA-4A) EquIPPed with Thilrmlnt A^4...f. Cro........Supercavitating Hydrofoil (Continued)'
The JRF-5a and the HRV-1 represent the only two hydrofoilseaplane config6urations developed and te:•ted in the United Statesto date, both sponsored by the Department of the Navy.
MODEL_________OT - -THURSTON AIRCRAFT CORPORATION REPORT NO. 9JSANFORD, MAINE DATE
LIIIc
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411
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MODEL THURSTON AIRCRAFT CORPORATION REPORT NO, 6912CONT .ANFORD, MAINE DATE
! I
Bow Skid Configuration BCG - 2L. 71 XAC
300 Flaps
S Gr. wt.-1b wave Ht-ft Headwirid-kt0 0 9450 I ý, to 9
9450 1/2 j to 69570 1/2 tol1 2 to 7
[ -Planing runs on which bounce occurredPlaning run. on which bounce did not occur
00 o
Sa) 0
4 FPOR BOUNCE FREE-
52. 56 60 64 68 72 76 80INDICATED AIRSPEED-KT
Fig. 72JRF-5G Airplane
BuNo 37782
UPPER HYDRODYNAMIC LOrTG7TUD.T;AL STABILITY LIMIT
REF: U.S. Naval Air Test Center, Report No. FT2121-35R-65, dated 25 July 1965
MODE. THURSTON AIRCRAFT CORPORATION M*POlWT No. 6 912CONT_ SNFORD, MAINE DATE
Bow Skid Configuration 13Gross Weight -. 9,450 1b, CG - 21.7% MAC
Wave lHeight - 1 ft, Headwind - 5 to 10 ktSurface Temiperature - 640 F
80------------------------ 030, FlapsJ
I - - ...... -0600 Flaps
700-R 600o- .. .. ..LIh
•5C -- 0- *- -,-0 0
0
400
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10 20 30 40 50 60 70 SOGLCULATED WATERSP['l-R(T
JRF-5G AirplaneBuNo 37782
POWER REQUIRED FOR PLANING VERSUS' WATERSPEAlD
FPit. 7'3
PEF: U.S. Naval. Air Test Center, Report No.
FT2121-35R-(;5, dated 25 July 1965
MODEL THURSTON AIRCRAFT CORPORATION REPORT NO, .. 1 2CONT,_ UNFORD, MAINE DATE
tI Agit 92
Bow Skid Configuration BGross Weight-L ,450 Vh 1.,M.
Wave Height -1 ft
AA
C.l 'ýjL ""1 2,c - t 3d'i 43. 1 s rk .1-LbIwin - U k;. L (3
10' p M'.p Fl ap
lc-FT22135R65 date ta2pm Jul 1965-p~d47k
MDI..~~~H ad"ITO AIRRAF -OPRO R7POR NOk61CON ____________ FAlapRD 9A.N DATE _____
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MDLTHURSTON AIRCRAFT CORPORATION REPORT NO. 69
SONY__________ UNPOW MAINE DATE ________
Bow Skid Coilfiguration BG r,3s s W ei~ght - 9,570 lb, CG - 21,7ý` MACW'ave Heiqht - 1/2 ft. Surface TemmorAý-11r- %
Wind Velocity - 7 kt from 20O' Loft
i I I
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•BuNo 37782TIME HISTORY OF A TAIE-OFF
V -:F' TI.i. Nriol Atr Tl l' Vetiter, li., pw l Nis. F I') I')1 I .61,
date 25 Jp 1961
MOD L -THURITON AIRCRAFT CORPORATION *P I1RT NO.SANWU, MAINI OAtK
PME 9 5
Blow Skid Configuration B
Gross Weight -9,450 lb, CG - 21.7% M.AC,,iv~ 11ljiL- 1L/2 ft, Surface Ixernpcature -64:"
60 F'laps
C4 -
q Ci 11 ~ffiL10IC -
'o.7
SINEHSOYO OMLLN~
REF U.. Nvn Ai' Tst E'ter Reortto
FT2213~-65 dte 25duy 96
MOEL___________ THRSONAICRFTCQPRAIO RPOTWOoo1
CON_______________ UAUDD, AIN DAE ________boo_
Bow Skid Configuration BCG Position - 21.7% MAC
600 Flaps
je jj~mn-ijb VTI Qt~---lb W-jRc tI -ftndIthrough 45 945016 E
A Gthroucjh 63 9570 1/2 to 1 5 t 1
-- 01----- -m
cr in*ntmPo Uv
00
4 5 6 7 a 9 .10 11 12RATE OF SINK AT TOUCHDOWN - FT/SEC
Fig. 78JRF-5G Airplano
BuNo 37782
CG NORMAL ACCELERATION V"' SINK RATE
REF: U.S. Naval Air Test Center, Report No. FT2121-35R-65,dated 2.5 July 1965
MODEL________ THIURSTON AIRCRAFT CORPORATION REPoRT NO, J91~2J&..CONY__________ MIANNN, MAINE DATE
Bow Skid Configuration 13Gross Wz.ight - 9,450 1b, CG - 21.7% MAC
Wave Height - 1 ft, Headwind - 5 to i0 kt
Ci
20'0 30°° •I•
m": 60, Filaps
lo-j•00
" 200C "'KLu ioo 100
2.8000 p. .1500
20 30 40 50 60 70 s0CALCULATED WATERSPEED - KT
Fig. 79JRF-5G Airilane
BuNo 377 2
CONSTANT SPEED FOILBORNE CHARACrERISTICS
IREF: U.S. Naval Air Test Center, kpmrt No. FT212i-'iii-(65,dated 25 July 1965
MOon_. THURITON AIRCRAFT CORPORATION REPORT NO, 69192DONT &WIWORD, MAINE DATE
r4-
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REr: Thur'ston Aircraft Corporation, Report No. 6902,
dated February 1969 (Rlef. 130).
~M uLTHURSTON AIRCRAfT CORPORATION WORT NO. 6912CANT______ UNiiu UNow DAT1 _____
IlI! 'I ' i
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Fig.82A Hydrofoil No. 1 Retracted
Fig. 8213Hydrofoil No. IExtended 22"on Strut No. 2
(Ref. No. 129; TAGReport 6702-3)
MD THURSTON AIRCRA"f CORPORATION RIPORT No, ..~aa....CONT_________ SANFORD, kAINK DlATE______
II III
VT. Hydrofoil Application to Seaplane Desigi
A. Longitudinal Location
Development of a hydrofoil configuration for seaplane operationmust be conducted parallel with the basic aircraft design. The foillongitudinal location along the hull bottom is most critical due tofoil-strut L/D force vector oscillations occuring from heave, trinmchanges, and wave front variations experienced during take off; itis imperative that the resultant L/D vector angle does not m~veexcessively - creating pitch trim oscillations that cannot be cor-rected by normal pilot control reaction.
While this operational condition is more critical for relat-ively small seaplanes of low mass and moment of interia comparedto long range open sea boats, any sudden shift of hydrofoil result-ant vector will necessitate a rapid trim correction adding to thehorizontal tail load and so prolonging take off (due to increasedloading of the wing and foil).
Reference 130 presents tho results of an initial, study concernedwith the comparative location of a single surface-piercing hydrofoilon the HRV-1 test bed. Flight test data confirmed that the hydro-foil-strut combination L/D vector must be located to pass ahead ofthe most forward center of gravity location anticipated duringseaplane operation.
The hydrofoil must be positioned with the realization thatthe nearer the foil-strut L/D vector approaches the seaplane cg,the greater the landing load impact factor will become relativeto a more forward location. Of course, since the hydrofoil is anexcellent water landing impact load alleviation device, any foilmaximum landing load factor will be considerably less than that ofthe basic hull (Reference 129, page 16). Countering the more forwardlocation of a foil to reduce impact loads is the additional considera-tion that a forward location tends to increase longitudinal pitchchanges with foil lift variations during take off and will resultin increased nose up pitch during the landing run out.
As an initial approximation for basic design, the singlehydrofoil center of lift should be positioned .35 to .50 MAC aheadof the airplane normal cg location. The proper longitudinal locationof a hydrofoil for the HRV-1I is shoWn on Figure 83 referred to thenormal gross weight cg.
.9. Extension versus Sea State Capability
While it may be properly agreed that no substitute exists forthrust and lift to reduce water contact time and run during takeoff, these factors cannot reduce landinp impact into a rough sea tothe degree possible with a surface-piercing hydrofoil. Therefore,
"NO_ __ THURSTON AIRCRAFT CORPORATION REPORT NO. 6912CONT IANFOSO, MAINS DATE
FARE 10
B. Extension versus Sea State Capability (Continued)
tne amount ot roil extension to provide Rea state capability Inrough seas becomes another major factor to be considered as thebasic seaplane design develops.
Neglecting power, a hull capable of handling four foot seasshould be able to negotiate eight foot waves if the hydrofoil ispositioned four feet below the keel. Actually, this will not beso, since the airplane first must have the capability to climb overthe hump and plane before it becomes fail borne. While excessthrust at relatively low hump speed will materially assist inreducing damaging wave impact duration, the airplane must notexperience foil unporting prior to attaining sufficient speed topermit aerodynamic control about all three axes (see discussionof following Section D).
Hydrodynamically, subject to the limitation of hydrofoilsupport strut drag on the margin of excess thrust, a properlydesigned hydrofoil may be located as far below the hull as designsea state conditions require. Practically, design compromise willbe necessary in the areas of handling qualities, support strutcolumn rigidity and weight, as well as retracted storage require-ments and retraction system weight.
As shown by the test results of Reference 129 and Figure 84,increasing the strut extension from 17 inches to 22 inches on theHRV-1 reduced the hydrofoil landing impact factor by 40% in roughsea conditions. Since the surface-piercing hydrofoil tends tosubmerge upon rough water contact, it is apparent that increasedstrut extension provides a greater deceleration time interval;resulting in reduced hull bottom contact velocity. (As a matterof interest, a 22 inch st'rut extension on the l1RV-1 correspondsto a 54 inch extension for the H11-16 "Albatross" amphibian.)
While maximum strut extension is desirable for rough seaoperation, intermediate extension positions should be used fortake off in reduced sea state conditions. Through this procedurestrut drag is reduced, permitting minimum take off run and timeunder conditions usually accompanied by relatively low surfacewind ities. .However, it is recommended that all land!ngs bemade a, maximum strut extension to reduce hull bottom platingpressurL loadings.
C. Impact Load Factors and N-ottom Pressures
The effect of hydrofoil extension as a landing load alleviationdevice to reduce maximum impact load factor and hull bottom pressuresis demonstrated by test data for the IIRV-1 presented in Figures 84and 85. Impact loads with the extended foil were 1/3 the basic hullvalues, while maximum bottom pressure loadings were reduced 35%.
Carrying these reduced loadings into the hull structure willresult in considerable savings in both airframe complexity and weight.
MODEL THURITON AIRCRAFT CORPORATION REPORT No. 6912COUT. __ANFORD. MAINE DATE
PAN
C. Impact Load Factors and Bottom Pressures (Continued)
Rni a 4van vvnx aivfa riatlr-.4 aaa will 1ho v-a*1lwad a
reduced airframe cost. Experience with the hydrofoil systeminstalled on the HRV-1 has indicated the complete system, includ-ing structural provisions and retracting mechanism, can be installedfor less than 4% of the airplane gross weight. A 35% reduction inbottom pressure loadings should provide at least a correspondingweight reduction in hull bottom plating and supporting structure;a saving in weight and cost that will permit installation of theseaplane hydrofoil system as a balanced structural trade off. Asa result, seaplanes designed for hydrofoil operation realize in-creased sea state capability without weight penalty. In fact, TACpreliminary studies have indicated that a complete hydrofoil systemfor a 90,000 pound seaplane designed to unport at 60 mph shouldweigh less than 3% of gross weight, including foil, strut, retract-ion system, and supporting structure. As presented in Chapter VTTT,the larger the seaplane the smaller the percentage of gross weightthat must be allocated to the hydrofoil system; the attendant re-duction in hull weight permits incorporation of a hydrofoil systemplus increased payload and sea state capability at a fixed grossweight.
To take full advantage of the hydrofoil system described inthis study, hull design requirements for hydrofoil seaplanes shouldbe revised to include load alleviation benefits associated withhydrofoil operation.
D. Hydrofoil SizeThe hydrofoil size for a given seaplane configuration must be
based upon:
1. desired unporting velocity
2. hydrofoil section properties
3. airplane trim angles during take off run
4. available thrust versus velocity during take off
5. hydrofoil and strut system drag versus velocity.
1. Of all these parameters, the desired unporting velocity requiresmost thorough initial consideration. The airplane must be aerodynami-cally controllable about all three axes at unporting speed or it willbecome unmanageable; resulting in an aborted take off, or, more likely,a damaging water loop at fairly high speed.
For small seaplanes up to 6,000 pounds gross weight, sufficientaerodynamic control should be available at unporting speeds of 45 to50 mph; larger aircraft with higher wing loadings will require higherunporting speeds to assure sufficient aerodynamic control. Once foil-borne, the single hydrofoil seaplane is perched upon a pivot hinged
MODEL THURITON AIRCRAFT CORPORATION REPORT NO. 6912 ,CONT__r SANFORD, MAIN DATE
ri
at the water surface, requiring *urfaoo control responna in muffleientdegree to provide trim and stability until airborne. Therefore,unporting speed is basically an aerodynamic consideration ratherthan hydrodynamic, and must be established prior to determining
hydrofoil area.
2. Fi r aircraft use, as prev iously noted on page 19, the hydro-
foil should be of supercavitating type; configuration propertiesare set forth in detail in Chapter TIT.
3. Airplane trim angles are required to determine wing and hydro-foil lift during the take off run and at unporting. The hydrofoi. Iincidence angle relative to the seaplane reference line must be set
to prevent hydrofoil ILft from heaving the airplane into an unpoi'tedcondition prior to the desired unporting speed (and related aero-dynamic control velocity). Most seaplanes trim at approximately8 degreesduring planing, and this angle could be considered forpreliminary design purposes.
4. An adequate thrust margin must be available to assure rapidtransition from hull displacement to the planing hydrofoil regime.This requirement is particularly critical for heavy sea stateoperation where wave impact duration and relative hull velocity atimpact should be at a minimum. Since hydrofoil aircraft may experi-ence two hump regions of operation, the first when the hull planesand the second when foil lift displaces the hull above the water
surface, it is necessary that the thrust margin be maintained athigher velocities than necessary for basic hull transition from thedisplacement to the planing mode. As the foil. comes into action,sufficient thrust margin must be available to overcome hull, strut,
and foil hydrodynamic drag as well as the aerodynamic drag of theairplane; and with sufficient margin to continue take off accelera-tion through hydrofoil unporting. Complete ventilation of thehydrofoil and support strut will materially reduce system drag asvelocity increases toward unporting speed.
Propeller driven aircraft characterstically experience adecrease in thrust with velocity during the take off run, and mustbe designed with an excess thrust margin prior to hydrofoil unport-ing. Turbo Jet aircraft normally experience a slight thrust increaseduring the take off phase, permitting a matching of static thrustto the margin desired during unporting. For either type of pro-pulsion system, other design factors such as STOL performance maydetermine thrust requirements; however, to assure smooth unportingand a controllable take off from the planing hydrofoil, adequateexcess thrust margin must be maintained at higher speeds than isnecessary for conventional hull configurations.
5. Hydrofoil and strut drag during take off must be determinedwith the view of establishing the minimum strut cross sectionnecessary to provide adequate structural. rigidity, and the minimum
MOD _ THURSTON AIRCRAFT CORPORATION REPORT NO. 69 12CONT? SANFORD, MAINE DATE -
I II I
D. Hydrofoil Size (Continued)
foil area required vo provide desired iift at uriportirng. Examplesof hydrofoil area calculation follow.
a) 2300 pound gross weight HRV-1:
Hull trim angle upon the step = 7.50; wing CL at this hullangle = 1.65; S 7 170 sq. ft.; desired unporting speed of40 knots (67.5 fds).
(i) Wing lift . 1.65 x .00119 x 170 x (67.5)2
-L 1520 lbs.S~w
(ii) Foil borne load contribution = 2300 - 1520LH = 780 lbs.
Foil CL = .27 (Ref. 45, Pg.13)
-o 62.4/32.2 - 1.94 for fresh water
SH L H 780 = .67 sq. ft.CLH / 2 .27x1.94/2 x (6775-
It should be noted that an axial load of 780 to 800pounds was frequently recorded in the HRV-1 hydrofoil supportstrut, but was not exceeded. The HRV-1 support strut, foil,retraction system, and hull structure reinforcement weighed73 pounds (3.2% design gross weight).
b) 90,000 pound open ocean seaplane (preliminary design):Wing CL at unporting a 2.2; Sw = 2000 sq. ft.; desired
unporting speed of 50 knots (84 fps).
(i) Wing lift = 2.2 x .00119 x 2000 x (84)2
L = 37,000 lbs.w(ii) Foil borne load contribution a 90,000 - 37,000
LH = 53,000 lbs.
Foil CL = .26 (Fig. 24, aC- 80, AR = 4)
LSH = H 2 -2ý000 T 28.5 sq. ft.C'LP/2 v2 .26 x 1.9 4 /2 x (8 4 )
Span (AR of 4) = 13 ft.
System and structural support weight (60 wedge, steelfoil) are estimated at 2540 lbs, or 2.8% of design grossweight, including hull reinforcement and retraction provisions.
NOTE: Since heavy sea state operation will normally be afcompaniedby surface winds which decrease the water speed for a given winglift value, the decreased contribution of' hydrofoil lift (or,conversely, the incrAased hydrofoil area required) will have to betaken into consideration when determining unporting speed at thedesign sea state conditions. The use of a flapped hydrofoil couldbe most beneficial under these conditions.
MODI.L THURSTON AIRCRAFT CORPORATON HPORT NO. 6912CONY .a.fO.., MAINE DAT
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MODEL THURSTON AIRCRAFNT CORPORATION REPORT NO. fi. 2.L...
INOD AIEDT
FAIR 109
VIT. Hydrofoil Seaplane Design Optimization
A. Design Factors for Integration of Hydrofoil and Seaplane
As discussed in Chapter VI, a successful hydrofoil equippedseaplane must consider hydrofoil effect upon airplane performance,handling qualities, and structural design. Thv hydrofoil altersthe mode of operation on the water so dramntically that ndding awell designed hydrofoil system to an existintr senplane withoutmodifying the powerplant or control systems would probably resultin an unsatisfactory combination.
Factors to be considered during the initial design of ahydrofoil seaplane are:
1. Hydrofoil unporting speed2. Excess thrust at hump and unporting speeds3. Airplane stability and control, particularly during the
unporting and foilborne phases.4. Spray pattern in relation to powerplant ingestion and
airframe impingement5. Hydrofoil performance and load capability6. Hull design considerations reducing required hull strength,
and resulting weight savings7. Hydrofoil retracting design to maximize airborne performanre.
B3. Stability and Control
Experience to date with two full scale hydrofoil test seaplaneshas shown that basic airplane stability and control are inadequateat the low speed end of foilborne operation. The airplane is placedatop an extended strut at speeds below stall; and must remain stableduring unporting and take off acceleration maneuvers through itsinherent aerodynamic stabil.ity and by the pilot's control. Duringplaning, a conventional seaplane is acted upon by hydrodynamic andaerodynamic forces which combine to produce a stable condition inpitch and yaw, with a mildly unstable condition in roll; however,to maintain a wings level condition, seaplane ailerons are designedto provide adequate control at very low airspeeds. At higherplaning speeds, the elevator and rudder become effective to provideaerodynamic pitch and yaw control.
When equipped with a hydrofoil, the seaplane is raised outof the water and the stabilizing hydrodynamic forces nre replacedby a destabilizing force vector from the foil. This vector actsabout the airplane cg, producing upsetting moments which can onlybe counteracted aerodynamically. If the design permits large foi lvector moment arms about the cg coupled with inadequate aerodynamicstability and control at these slow speeds, the nirplnne hecome,
NOOK THURITON AIRCRAFT CORPORATION REPORT NO. 6CONT__ SANFORD, MAINE DATE
11III
0. St at I I it ty tid Con t rlI (con t. inued)
uncoiiti-clldlble al. utiporting; under such conditions transition toft(- pinaning c'ondi tion woribi~ not he attainable and tile take of' imustOv aborted.
For this reason, tile low spe&~d (-lirlr'arter'ls tics ot' the airplaineand thle liydr'ofoi 1-struit rombiriatLon must be oarefully analyzed. Th ehyd roFo ilI.- st rut -'esuiltant 1./I) vector must riot only pass close to therp (pet, Chapter VI . A) , but must also stay as nearly constant asipossible during tinport~ing and at slow speeds. Any change in i./nwil 1 hange the verctor moment arm about the airplane cgr, result-ing.I, p it. cl trim changes,* Figure 86.
'File upJSet t itg e~l'ertS Of' thle I./D t'orce vector' changes can bemin in izi erl by reduc ing the Str'ut length. As revilewed in Chapter VI,this lenigth normally will be a compromise bet~ween handl ing qual ities,Atriit sys tern weight , desitgn sea state wave heieIghts, and minirinurr
*sprav pattern conditions. Sinoe any foil will ventilate when I t* ~~~inports, in ordler to ma inta in nearly steady state F'o I cond t ionns* hlim it rignpo rt i lug and tile niarly phtase of' f'o)i I planing, cav itat ion
itid vent il1ati~on of' thle Coi I ind strut must occur prior t~o u~npor'ting~r.
Ii r'trf' 86 -diows I hso'ci actinug oui the Foiliboi ne itirpi onein thle I onri tud inal plane.* The t'ome and a ft location of' the hrydro-fol iIs related t~o 'oiigitud mia control power. Moving tire hydrof'oil.alft shortens tile moment arm of' lthe ta il about. the hydra t'oi I , thereby.in t only requiring more nose ripl frim but larger elevator deftlectionsto mainota in control . In addi ti~on, this Increases the loaading on
ith Foil and wing, sitirie the tail Force is increased in the down-lward direction. Vr~ oistuI ' t kiions itl fieF'-,tu ,I) nIt- mesull taritteorre of' the fo ilI) wiI requi re changes in H (resultfant. rorce of'the ta 1 omait n qiIiritma1 icnrT
From the aerodynamic( viewpo int , the a i rnl ane rmust p~ossesssufficient tstabi I ty and control itri p1 tchi to permit holdi1ng thedesi red trim attitude. 'This c(an mearn larger thari nor'malI controlsurfaces, or' incrmeased effter'tiveie~ss th roilgh houndry layer coat ruIais tiise onl some S.(II i ri'planes.
In the ma! mode, filet a i rpl;rnisi destali Ii red when loil bornedue to tile inc-reased t'o iI-strujt to rc, vic tor moment a r'm ar't i ri abontthe (g. 'Iii Is dtecrteased s tabh Ii it v re~sul t s Iii a more rapid( "wing-dr0o)" mrot i oi r'equi ri rig- I aI r'ger aridI rol re ra.pid a1 1 I eror i I nipat to ma), ill-fa inr a w i rigs- I evvl at t i tude . lI'l pr-tdorniruiril I ta-'tots a IA'f t i ng
r'01I I Stithl) i t V a kt'e St mut !erit'th :1l t[II ' - t i-iit iuarnbl rit ion Sidvt
lastIly) thile yo ; i%, odt- di i-(, jt aili 1 st ali I I i i is a I so cteperiieiiulpon till lonrii tuildinal locat ion of' file t'oi l-s rut system wi Ill roespectin) tho 0 r'plaiir' -rg al wellI as- Iit" side Volit'5 restiul t rigj I'ioii taiI-
t I'ia I vow. Nlov in ri thle ta j I a id si ý irlit a f t Wi I I I-diri'e Ilii, S 1(1 I o-d
MOBIEL _______-THURSTON AIRCRAFT CiJRPORATION REPORT NO. 69 1)2CONT ________ SANFORD, MAINE DATE ________
I I
7 B. Stability and Control (continued)
capability, improving this condition. Yaw instability is of' greatestMigniflannea dirnrig the ,nporting phase, when the strut can make itsside force contribution. After the foil unports, the strut is mostlyclear of the water with its side force input essentially eliminated.The major side force contribution then comes from the foil and isof relatively minor nature, acting at higher aerodynamic speedsaccompanied by more effective rudder control.
C. Performance
The waterborne performance aspects of hydrofoil seaplanedesign center about the excess thrust available at hump and unport-ing speeds. Excess thrust must provide bufficient acceleration torealize acceptable take off times and distances. To meet theserequirements, available thrust must be as high as possible, con-sistent with other design requirements, and the airplane total dragmust be kept at a minimum. Factors affecting the airplane totaldrag are:
1. Hump speed2. Unporting speed3. Hull hydrodynamic drag4. Hydrofoil-strut combination hydrodynamic drag5. Aircraft aerodynamic drag.
IHump speed occurs as the hull transitions from a displacementto a planing body and usually occurs at a speed where excess thrustis minimum; normally coinciding with the speed at which total dragis a maximum. In the case of a conventional seaplane without ahydrofoil system, the total drag at; hump speed is predominantlyhydrodynamic with a minor contribution from aerodynamic drag. Thishydrodynamic drag peaks at hump speed as the displacement hull risesin the water; then diminishes as the hull begins to plane. Withthe addition of a hydrofoil system and Its associated drag, thetotal hydrodynamic drag will be greater than for a conventionalhull at any given speed prior to hydrofoil unporting.
The normal take off thrust-drag relationship is further alteredsince the hydrofoil can be designed to unport at speeds unrelatedto the hump speed of the basic hull. If the hydrofoil were designedto unport at speeds below the basic hull hump speed, a comparativelylarge foil would be required. With such a configuration, the totaldrag would increase rapidly until unporting occured and then decrease.This combination is undersirable due to the unnecessarily large,heavy foil system and the poor handling qualities associated withlow speed unporting operation.
The more desirable configuration would be designed to unportslightly above hump speed; permitting a reduction in foil system
wOo&G. THURSTON AIRCRAFT CORPORATION RPOR NO. 6912=cap" NAwORD, MAINE DATE
ki
PAlS 112
1"C. Performance (Continued)
size combined with improved aircraft handling qualities.
If unporting is delayed to speeds considerably above humpby further reducing the foil system size, hydrodynamic drag willbe reduced at any given speed; but will maintain an approximatelyconstant level beyond hump speed, since V2 drag of the submergedfoil and strut will balance any reduction of hull drag due to hullrise. The disadvantage with this arrangement is the resultingextended period of high drag accompanied by slow acceleration;extending take off time and distance while exposing the airplanehull to increased periods of wave impact at higher speeds.
Foil size calculations and other performance parametersmust also consider the landing mode, to preclude foil submergenceupon landing contact due to foil overloading. This requirementis quite important since submergence of the foil would not onlydefeat its prime purpose of protecting the hull from wave impactloading, but could also create a strong secondary reactive forceplacing the airplane in undesirable attitudes leading to a highspeed water loop or a violent pitch ejection high above the watersurface.
D. Spray Patterns
Experiments have shown that spray height and thicknessincrease as foil angle of attack and submergence depth increaseqoccurring at the slower foilborne speeds where maximum lift co-efficients are being generated. Figure 74 shows foil spray patternsfor the JRF-5G with spray height maximum at a water speed of 39knots, decreasing as speed increases. To minimize drag, it isimportant to minimize the amount of spray impingement on the air-frame, particularly on flaps and tail surfaces. Excessive sprayrepresents wasted thrust, resulting in increased take off timeand surface run..
P:. Hull Design
The hull should be designed to reflect the reduced impactloads resulting from hydrofoil operation, and to accommodate thefoil system in the retracted position. Hull bottom loads shouldbe calculated on the basis of operational speeds somewhat aboveunporting but well below take off. Further reductions in bottomplating should be realized from decreased bottom pressure loadingspresented in Chapter VI. The resulting saving in hull weight shouldbe greater than the total weight of the hydrofoil system (seeSection D. 5 of Chapter VT, and Chapter VITT).
MODEL THURSTON AIRCPAfT CORPORATION REPORT NO. 912CONT "WORD, MAINE DATE
•)P•lE 11
F. Hydrofoil System Optimization
To realize maximUm performance, the hydrofoil should completelyrecess into the hull. A single hydrofoil having dihedral coincidingwith hull deadrise, and supported by a single strut, is best suitedfor seaplane hull installation. The support strut could retractthrough the keel, with the hydrofoil housed in a hull bottom recess.The Thurston Aircraft Corporation HRV-1 design is typical of thisinstallation (Figures 80, 81, 82 and page i).
MODEL THURSTON AIRCRAFT CORPORATION REPOT NO. 612CONT_ _AORhh MAINE D04T
I I I Jil I
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Fig. 86
Forces in
Longitudinal Plane of Foilborne Seaplane
MO _ _ THURSTON AIRCRAFT CORPORATION REPORT NO. , .6912CONT SANFORD, MAINE DATE
I
VIII. Hydrofoil Seaplane Development
In conclusion, it is most importsnt to understand thatmaximization of operational benefits offered by the hydrofoilseaplane can only be realized when the entire configuration isdeveloped for hydrofoil operation.
In this regard, the following design areas require further
study:
(a) Hull hydrodynamic aonfiguration(b) Hull structural loading reductions possible during
displacement and impact conditions
(c) Hydrofoil system weight versus seaplane gross weight
(a) Taking full advantave of hydrofoil lift, it is quitepossible that a modified semi-chine or chineless hull can bedeveloped. In addition, a stepless, faired step, or retractablestep hull configuration should be possible, using foil lift andexcess thrust to assist in planing at an early point in the takeoff run. A proper study of these interrelated factors is beyondthe scope of this report; but should permit design of a streamlinedhull form capable of being pressurized with minimum weight penalty,while offering a material increase in crilising speed and rangecompared to prior seaplane configurations. The hydrofoil shouldretract flush with the hull bottom surface, presenting no increasein form drag when stowed.
(b) As noted in Section C of Chapter VI, a material reduct-ion in impact load factors and hull bottom loading will be realizedfrom hydrofoil operation. To take full advantage of the availablereduction in hull structural weight and complexity, specificationdesign requirements must be reduced accordingly. The savingspossible from reductions in structural weight and constructioncomplexity will offset the weight and cost of the hydrofoil system,while providing increased sea state capability and a probableincrease in payload for a given gross weight. Any serious effortto design a new open ocean seaplane should be preceded by aninvestigation of hull loading reductions possible with the hydro-foil operating in heavy sea state conditions.
(c) As shown in Figure 87, the weight of the hydrofoilsystem referred to seaplane gross weight should reduce slightlywith seaplane size. While this presentation is based upon pre-liminary parametric studies, further detail design will be requiredto integrate a working hydrofoil system into the seaplane conaigura-tion and operational specification requirements. For preliminarydesign study, the percentage of gross weight set forth in Figure 87indicates that with attendant reductions in hull weight the hydro-foil will permit development of a superior seaplane without weightpenalty.
MOn._ THURSTON AIRCRAFT CORPORATIOI IMEPORT NO. 6912CON____ SANOR, MAINE DA
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4 117I I II
IX. Bibliography and Reference List
A. Historical References
1. Aeromarine Originsa H.F. King; Putnam and Company Ltd.(Aera Publishers Inc. in the USA), 1966.
2. British Flying Boats and Amphibians 1909-19521G.R. Duval; Putnam and Company Ltd. (Aaro Publishersin the USA), 1966.
3. Jane's All the World's Aircraft, 1932.
4. The Hydrofoil Boat, Tietjensl Werft-Reederei-Hafen andThe Yearbook Deutsche Luftfahrtforschung p. 1361, 1937.
5. Hydrodynamic Lift Through Hydrofoils, Design of a StableFoil System, Grunberg; L'Aerotechnique No. 174 andL'Aerotechnique No. 217, p. 61, June 1939.
6. Brief Historical Review of the Hydrofoil Boat;H.O. Hollenberg; Systems Analysis DiviLion, Report No.RRSY-60-53, Bureau of Naval Weapons, Washington, D.C.,August 1960.
B. Hydrofoil Bibliography Lists
7. Hydrofoil Bibliographyl Glen J. Wennagel; DynamicDevelopments, Inc., Babylon, N.Y., September 1957.
8. Hydrofoils, Ar. Annotated Bibliography SB-60-36;K.D. Carroll; Lockheed Missiles and Space Division,Sunnyvale, California, September 1960.
C. Hydrofoil Study Reports
California Institute of Technology
9. Report No. 47-2 April 1955 by Parkin, Perry and Wu;"Pressure Distribution on a Hydrofoil Running Near theWater Surface"
10. Report No. 47-3 December 1956 by Parkin and Peebles;"Calculation of Hydrofoil Sections for PrescribedPressure Distributions"
11. Report No. 47-4 September 1955 by Wu and Perry;"Comparison of The Characteristics of a HydrofoilUnder Cavitating and Noncavitating Operation"
ThMTHURO AIRAR CORPORATION REPORT m. 6912oO UGIT .- I.eumm, -I[ I DATE
California Institute of Technology
12. Report No. 47-6 February 1956 by Parkin;"Experiments on Circular Arc and Flat Plate Hydroftonlin Noncavitating and Full Cavity Flows'*
13. Report No. 47-7 February 1956 by Kermeonl"Water Tunnel Teast of NACA 66-012 Hydrofoil inNoncavitating and Cavitating Flows"
14. Report No. 47-9 December 1957 by Parkin;"A Note of the Cavity Flow Past a Hydrofoil in a Liquidwith Gravity"
15. Report No. 47-10 February 1957 by Parkin and Kermeen;"Water Tunnel Techniques For Force Measurement onCavitating Hydrofoils"
16. Report No. 47-11 March 1960 by Cumberbatch and Wu;"Cavity Flow Past Two Slender Pointed Hydrofoils"
17. Report No. 47-12 May 1960 by Cumberbatch;"Cavitating Flow Past a Large Aspect Ratio Hydrofoil"
18. Report No. 47-13 June 1960 by Cumberbatch;"Accelerating, Supercavitating Flow Past a Thin Two-Dimensional Wedge"
19. Report 47-14 September 1960 by Kermeen;"Experimental Investigations of Three DimensionalEffects on Cavitating Hydrofoils"
CONVAIR
Aeromarine Test Center, San Diego, Cal.
20. Report ZH-083A - May 1952;"An Exploratory Investigation of the Practical Aspectof Hydrofoils as Applied to Waterbased Aircraft"
21. Report ZH-102 - July 1955 o"Modal Experiments with Hydrofoils and Wedges for RoughWater Seaplane Design"
22. Report ZH-I-3 - August 1957;"A Hydrofoil System for the JRF-5 Airplane"
23. Report ZH-127 - March 19581"Hydrodynamic Characteristics of Two MACH 3 Designs"
24. Report ZH - 132 - February 1959;"Supersonic Attack Seaplane - Final Report of DesignStudies"
moon.r THURSTON AIRCRAFT CORPORATION upT #o, 6912I, CONT_ ___l__• Di. MAIN...ATE_
I • ICONVA3th
Aeromarlne Teat center, Ban Liegop Ual.
25, Report ZH-136 - April 19591"A Hydrofoil System for a MACH 3 Seaplane"
26. Report GD/C - 63-021A - February 1963;"Superoavitating Hydrofoil Studies"
27. Report No. U419-67-011 - September 1967, Conolly and Ball;"Towing Basin Tests with a One-Eleventh Scale Model ofa High Density Seaplane Configuration"
Cornell Aeronautical Laboratory
28. Cal. Report No. BB-1629-S-1 - August 1962, Crimi andStatler; "Forces and Moments on an Oscillating Hydrofoil"
Dynamic Developments, Inc.
29. Report No. 107, Application of Supercavitating Hydrofoilsto High Performance SeaplanesPart I Summary Report; John Luack 1958
30. Report No. 108, Application of Supercavitating HydrofoilsTo High Performance SeaplanesPart I1 Steady State Hydrodynamic Loads Calculations;John Lueck, March 1958
31. Report No. 109, Application of Supercavitating HydrofoilsTo High Performance SeaplanesPart III Structural Considerations; Thomas Shervington,March 1958
32. Report No. 110, Gruen Tech. Rpt. 66, Prepared byGruen Applied Science Laboratories, Inc. Applicationof Supercavitating Hydrofoils to High PerformanceSeaplanesPart IV Aerodynamic Considerations
33. Report No. 111, Gruen Tech. Rpt. 67, Prepared by GruenApplied Science Laboratories, Inc. Application OfSupercavitating Hydrofoils To High Performance SeaplanesPart V Foil Flutter and Airplane Waterborne StabilityConsiderations
EDO Corporation
34. Report No. 4769 - 17 July 1958 by J. Kapsalia;"Structural Design Criteriat Grunberg HydrofoilSystem on JRF-5 Airplane"
MUOB. THURTON MEORAFT CORPORATION Epol N. 6912ouIr MAINE SATE -
Iii PAN
EDO Corporation
"The Development of a Damping Hydrofoil for RoughWater Landings of Seaplanes"
36. Report No. 4869 - 9 December 19581"An Experimental Investigation of the Effect of Size onthe Hydrodynamic Characteristics of a Surface-PiercingHydrofoil"
37. Report No. 4912 - 22 January 1959 by JT. Kapsalis:"Water Loads for the Grunberg Hydrofoil System onJRF-5 Airplane"
38. Report No. 4999;"Structural Analysis of Installation of GrunbergHydrofoil System on the Grumman JRF-5 Airplane"
Part I Forward Skid InstallAtionPart II Stress Analysis of Hydrofoil and
Supporting StrutsPart III Bow Skid and Hydrofoil Carry Through
Structure
39. Report No. 5741 - 13 April 1962;"The Equilibrium Configuration of a Towed Hydrofoil -
Strut System in Two-Dimensional Steady Flow"
40. Report No. 5743;"Final Report on the Development and PreliminaryDesign of a Helicopter-Towed Hydr.'ofoil Sea Pallet"
41. Report No. 6487 - 5 May 1964;"Proposal For The Model Test Development of a PeneratingSuperventilating Hydrofoil Installation for The GrummanHU-16 Airplane"
42. Report No. 6651 - November 1964;Final Report "Design and Installation of GrunbergHydrofoil System on the JRF-5 Airplane"
43. Report No. 6652 - October 1964Final Engineering Report "Instrumentation and PreliminaryFlight Tests of the JRF-5 Equipped with a GrunbergHydrofoil System"
44. Report No. 6653 - January 1965Final Engineering Report "Flight Tests of the JRF-5Equipped with a Grunberg Hydrofoil System"
45. Report No. 7016 - 7 February 1966 by L. Kaplan andR.J. Miko; "The Design and Model Testing of a SmallSingle Hydrofoil Installation for the i{U-16 Airplane"
mom THURITON AIRCRAFT CORPORATION napom NO.OOSUT MIUORD. MAINE DATE
[|-ph-f 121
EDO Corporation
S"Development of O give Hydrofoils for Mk 3 Mod 0• Seaborne Zqujp=9ntt Pinal Report"
47. Report No. 7489-1 - 23 December 1966 by P.A. Pepper andL. Kaplan; "Survey on Seaplane Hydro-Ski TechnologyPhase Is Qualitative Study"
48. Report No. 7489-2 - 28 March 1968 by P.A. Pepper andL. Kaplan; "Survey on Seaplane Hydro-Ski TechnologyPhase III Quantitative Study"
Grumman Aircraft Engineering Corporation49. Report No. PDR-140-1 - 12 April 1957;
"Summary Report - JRF Hydrofoil and Dynamic ModelTest Program" Phase I
50. GAEC & DDI - 3 October 1958;"Study of Hydrofoil Seacraft"Volumes I and II
Volume I contains chapters on sub and supercavitatinghydrofoils, struts and bodies of revolution, e8timatesof strut and hydrofoil weights.
Volume I1, devoted entirely to hydrofoil boats, containsuseful information on hydrofoil configurations, hullstructure to which the struts are attached, and someapplicable preliminary design analysis.
51. Report No. DA10-480.3 - 7 February 1962 by Baird, Squires& Caporalif"Investigation of Hydrofoil Flutter"
52. Report No. STR-MAR-100, 1 May 1962 by Dulmovits;"Hydroelastic Effects on The Lift of High SpeedHydrofoils"
53. Report No. DA Nonr - 3989.3 - November 1963 by Squires;"Hydrofoil Flutter, Small Sweep Angle Investigation"
Hydronautics, Incorporated
54. Report 001-1 - June 1960"Optimum Wing-Strut Systems for High Speed OperationsNear a Free Surface"
55. Report 0016 - January 1961 by V.E. Johinson, Jr. andM.P. Tulin; "The Hydrodynamic Characteristics of High-SpeedHydro foils"
iO00L TWURUTON AIRCRAFrT CORPORATION RKPORT NO.OONT__amO, MAINE SATE
PAU 122
Hydronautic , Incorporated
50. Report 120-1 - March 1901 by M.P. Tulin;
"1"80 Knot Wing-Strut System Design and Performance"
57. Report 001-7 - April 1962 by J. Auslaender"Low Drag Supercavitating Hydrofoil Sections"
58. Report 001-16 - September 1962 by V.E. Johnson, Jr. and
S.E. Starley;"The Design bf Base-Vented Struts for High-SpeedHydrofoil Systems"
59. Report 001-15 - November 1963 by V.E. Johmson, Jr. andS.E. Starley;"Low-Drag Base Vented Hydrofoils Designed for OperationNear the Free Surface"
60. Report 343-1 -, March 1964 by J.O. Scherer andJ. Auslaender;"Experimental Investigation of the 5-Inch Chord Modelof the Buships Parent Supercavitating Hydrofoil"
61. Report 463-i, Chapter 4 - September 1964 by R.A. Barr;"Trim Attitude and Pre-Takeoff Resistance of HydrofoilCraft"
62. Report 463-6 - January 1965 by T. Heieh;"Passive Load Alleviation on Supercavitating Hydrofoils"
63. Report 457-1 " November 1965 by R.J. Altmann;"Measurement of Cavity Shapes Above Ventilated Hydrofoils"
64. Report 498-1 - November 1966 by R.J. Altmann;"Model Tests of a 20-Ton Hydrofoil Sled"
65. Report 744-1 - March 1968 by R.J. Altmann;"Hydrofoil Craft Designer's Guide"
66. Report 001-14 - April 1968 by R.J. Altmann;"The Design of Supercavitating Hydrofoil Wings"
67. Report 121-5 - April 1965 by Marshall P. Tulin;"The Shape of Cavities in Supercavitating Flows"
68. Report 343-3 - September 1965 by Scherer and Auslaender;"Experimental Investigation of a Supercavitating Hydrofoilwith Trailing Edge Flaps"
69. Report 463-4 - June 1964 by B. Yim;"On a Fully Cavitating Two-Dimensional Flat PlateHydrofoil with Non-Zero Cavitation Number Near a FreeSurface"
_THUISTON AIRCRAFT OORPORATION RIN? wNO. 6912WINT JSANOR, MAINE DATE
S 123
Hydronautlas, Incorporated I70. Report 4 63-5 - July 9604 'by C.C. Nfiu;
"On Full Cavitating Hydrofoils Entering Gusts Under aFvso. Surface"
71. Report 465-1 - Deocember 1965 by T.T. Huang and H.H. Shih;"Investigation of Base Vented Hydrofoila"
Iowa, State University of
72. Proj. No. S-R009-01-01 July 19611"Tests of a Cavitating Hydrofoil"
The Martin Company
73. Report ER9433 - Jun* 1957 by E.G, Band and J.W. Cuthbert;"Preliminary Design Data for Water-Based Aircraft withHydrofoils or Skim"
74. Report ER10135 - March 1958;"Configuration and Model Lines of the Martin M329E-8 Supersonic Seaplane"
University of MinnesotaSt. Anthony Falls Hydraulic Laboratory
75. Tech Paper No. 30, Series B, April 1960 by J.M. Watzel!"Experimental and Analytical Studies of the LongitudinalMotions of a Tandem Dihedral Hydrofoil Craft in RegularWaves"
76. ProJ. Report No. 64 - September 1960 by Wetzel and Schiebel"Lift and Drag on Surface Piercing Dihedral Hydrofoilsin Regular Waves"
77. Tech Paper No. 36, Series B - December 1961 byLorenz G. Straub, Directors"Ventilated Cavities on Submerged Three DimensionalHydrofoils"
78. Tech Paper No. 37, Series B - December 1961 by Wetzeland Maxwell;"Long Motions and Stability of Two Hydrofoil SystemsFree to Heave and Pitch in Regular Waves"
79. Proj. Report No. 61 - May 1962 by Lorenz G. Straub,Director; "Tandem Interference Effects of FlatNoncavitating Hydrofoils"
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p• 124
St. Anthony Falls Hydraulic Laboratory
80. Proj. Report No. 72 - October 1964 by Schiebe and Wetzell"Further Studies of Ventilated Cavities on SubmergedBodies"
81. Proj. Report No. 68 - March 1965 by Wetzel and Foerster;"Force Characteristics on Restrained, Naturally VentilatedHydrofoils in Regular Waves"
82. Tech Paper No. 51, Series B - May 1965 by R. Oba;"Performance of Supercavitating Hydrofoils with Flaps,with Special Reference to Leakage and Optimization ofFlap Design"
National Advisory Committee for Aeronautics
83. WRL-725 - March 1944 by K.L. Wadlin;"Preliminary Tar.: Experiments with a Hydrofoil on aPlaning-Tail Seaplane Hull"
84. RM No. 1_.9A17 - March 1949 by King and Rockett;"Preliminary Tank Investigation of the Use of Single
Monoplane Hydrofoils for High Speed Airplanes"
85. TN-2453 - September 1951 by R.F. Smiley;"An Experimental Study of Water-Pressure DistributionsDuring Landings and Planing of a Heavily LoadedRectangular Flat-Plate Model"
86. RM L52D15 - September 1952 by Land, Chamblias and Petynia;"A Preliminary Investigation of the Static and DynamicLongitudinal Stability of a Grunberg Hydrofoil System"
87. RM L52J10 - December 1952 by King and Land;"Effects of Sweepback and Taper on the Force andCavitation Characteristics of Aspect Ratio 4 Hydrofoils"
88. TN 2981 - July 1953 by Weinstein and Kapryan;"The High Speed Planing Characteristics of a RectangularFlat Plate Over a Wide Range at Trim and Wetted Length"
89. TN 3092 - December 1953 by Coffee and McKanni"Hydrodynamic Drag of 12 and 21 Percent Thick SurfacePiercing Struts"
90. TN 3951 - March 1957 by K.A. Christopher;"Investigation of' the Planing Lift of a Flat Plate atSpeeds up to 170 Feet per Second"
THURSTON AIRCRAFT CORPORATION .MRT NO. 6912T_ _wow "M OAT[
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W.*4eial A~wnA, --'t4**&A far Aeranautios
91. RX L57A15 - March 1957 by Roy Stoiner;"Statistical Approach to *ho Estimation of Loads andPressures on Seaplane Hulls for Routine Operations"
92. RM L57GO5 - October 23, 1957 by Potynia, Hasson and Spooner;"Aerodynamic and Hydrodynamic Characteristics of aProposed Supersonic Multijet Water-Based Hydro-SkiAircraft with a Variable Incidence Wing"
93. TR-1355 - 1958 by C.L. Shuford, Jr.;"A Theroretical and Experimental Study of PlaningSurfaces Including Effects of Gross Section and PlanForm"
National Aeronautics and Space Administration
94. -Moro 5-9-59L - June 1959 by McGehee and Johnson;"Hydrodynamic Characteristics of Two Low Drag Super-cavitating Hydrofoils"
95. TN D-16 - August 1959 by Maki and Giulianetti;"Loq Speed Wind Tunnel Investigation of Blowing BoundryLayer Control on Leading and Trailing Edge Flaps of uFull Scale Low Aspect Ratio, 42 degree Swept WingAirplane Configuration"
96. TN D-119 - November 1959 by Johnson and Rasnick;"Investigation of a High Speed Hydrofoil with ParabolicThickness Distribution"
97. TR R-14 - 1959 by Wadlin and Christopher;"A Method for Calculation of Hydrodynamic Lift forSubmerged and Planing Rectangular Lifting Surfaces"
98. TN D-166 - November 1959 by Vaughan;"A Hydrodynamic Investigation of the Effect of AddingUpper Surface Camber to a Submerged Flat Plate"
99. TN D-187 - January 1960 by Christopher and Johmson;"Experimental Investigation of Aspect Ratio I Super-cavitating Hydrofoils at Speeds Up to 185 Feet perSecond"
100. TN D-220 - February 1960 by Stubbs and Hoffman;"A Brief Investigation of a Hydro-Ski StabilizedHydrofoil System on a Model of a Twin Engine Amphibian"
NIOUSTS AICAFT OIPRATIOM Rea NO. 6SmLE
DAT
S--• pm -. _
National Aeronautic* and Space Administration
101. TM X-191 - February 1960 by NcKann, Blanchard and Pearson;"Hydrodynamic and Aeiodynaemie Charsr.ri*r 4ea of aModel of a Supersonic Multijet Water Based AircraftEquipped with Supercavitating Hydrofoils"
102. TN D-728 - March 1961 by K. Christopher;"Experimental Investigation of a High Speed Hydrofoilwith Parabolic Thickness Distribution and an AspectRatio of T'
103. TR-93 - 1961 by V. Johnson, Jr.;"Theoretical arnd Experimental Investigation of Super-cavitating Hydrofoils Operating Near the Free WaterSurface"
Southwest Research Institute, San Antonio, Texas(Administered by DTMB) (Now NSRDC)
104. Tech Report No. 2 - 1 Nov. 1962 by Ransleben andAbramson;"Experimental Determination of Oscillatory Lift and VMoment Distributions of Fully Submerged FlexibleHydrofoils"
105. Tech Report No. 4 - 15 December 1963 by Abramson andRansleben;"A Experimental Investigation of Flutter of a FullySubmerged Subcavitating Hydrofoil"
106. Phase I Tech Report Task 1719, SWRI Project No. OZ-15J46by G. Ransleben, Jr.;"Experimental Determination of Oscillatory Lift and MomentDistributions on a Fully Submerged SupercavitatingHydrofoil"
107. Tech Report No. 1 - 15 August 1958 by Abramson and Chu;"A Discussion of the Flutter of Submereed Hydrofoils"
Stanford University
108. Tech Report No. 17 - September 1963 by Nimr and Perry;"Cavity Flow Around Cambered Hydrofoils"
Davidson Laboratory, Stevens Institute of Technology
109. Report No. 517 - December 1959 by P. Kaplan;"Longitudinal Stability and Motions of a Tandem HydrofoilSystem In a Regular Seaway"
moon THURSTON AIRCRAFT CORPORATION R00T NO. 6912cUET, _ _ "Mo__nm "a DATE
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110. Report No. 596 - January 1956 by J.P. Breslin and JW. Delleurl"The Hydrodynamic Characteristics of Several surface-Piercing Struts"
111. Report No. 668 - October 1957 by J.P. Breslin and R. Skalak;"An Explorntory Study of Ventilated Flows About YawedSurface Piercing Struts"
112. Report No. 698 - October 1958 by P.W. Brown;"The Force Characteristics of Surface Piercing FullyVentilated Dihedral Hydrofoils"
113. Report No. 704 - June 1959 by Paul Kaplan and W. Jacobs;"Dynamic Performance of Scaled Surface-Pierci-ig HydrofoilCraft in Waves"
114. Report No. 731 - July 1959 by P.W. Brown;"A Generalized Theory of the Impact Characteristics ofSurface-Piercing, Fully Ventilated Dihedral Hydrofoils"
115. Report No. 732 - October 1959 by G. Fridsma;"Longitudinal Stability of Surface-Piercing HydrofoilSystems Water-Based Aircraft"
116. Report No. 795 - November 1960 by G. Frisma;"Force and Moment Characteristics of a Surface-Piercing,Fully-Ventilated, Dihedral Hydrofoil"
117. Report No. R-856 - September 1961 by C.J. Henry;"Hydrofoil Flutter Phenomenon and Airfoil Flutter TheoryVolume I - Density Ratio"
118. Report No. R-911 - July 1962 by C.J. Henry and M. Raihan Ali;"Hydrofoil Flutter Phenomenon and Airfoil Flutter TheoryVolume II - Center of Gravity Location"
119. Report No. 952 - October 1963 by G. Fridsma;"Ventilation Inception on a Surface-Piercing DihedralHydrofoil with Plane Face Wedge Section"
120. Tech Memorandum No. 133 - April 1965 by J.P. Breslin;"Simplified Procedures for Estimation of the CavitationInception Speed on Two-Dimensional Foil Sections"
121. Letter Report No. 1096 - November 1965 by R.L. Van Dyck;"Development Tests of HU-16 Hydrofoil Aircraft"
122. Report No. 1115 - December 1965 by C.J. Henry andM. Railhan Ali; "Hydrofoil Flutter Phenomenon andAirfoil Flutter TheoryVolume III- Sweep and Taper
"AM _ --,ThUITON NROAF' CORPORATION EPOmT NO. 612OT__________N , isum -DAT
Davidson Laboratory, Stevens Tnetitute of Technology
12 . .. ..- - f.t-.. .'Q =Z! . CA d• t Z *;
"Finite Aspect Ratio Hydrofoil ronfigurations in a FreeSurface Wave System"
124. Letter Report No. 1180 - November 1966 by John Mercier;
"Force Measurements on a Rotating Variable Sweep Hydrofoil"
125. Letter Report No. 1332 - January 1969 by John Mercier;"Tests of a Variable Sweep Hydrofoil with Cavitation andVentilation"
126. Letter Report SIT-DL-69-1347 - October 1969 by R.L. Van Dyck;
"Model Tests of Hydrofoil Equipped Floats"
Technical Research Group (TRG)
127. TRG-141-FR - July 31, 1961 by Bluston and Kaplan;"Lateral Stability and Motions of Hydrofoil Craft inSmooth Water"
Thurston Aircraft Corporation
128. Report No. 6702 -1 September 1966 by David B. Thurston;
"Structural Analysis of H1RV Hydrofoil No. 1"
129. Report No. 6702-3 - February 1967 by David B. Thurston;
"Final Summary Report: HRV-1 Equipped with HydrofoilNo. 1 on Strut No. 2"
130. Report No. 6902 - February 1969 by David B. Thurston;
"Final Report: HRV-1 Flight Test with Aft Location ofHydrofoil No. 1 on Strut No. 2"
Ministry of Aviation, United Kingdom
131. R & M No. 3285 - December 1958 by Arlotte, Brown, Crewe;"Seaplane Impact - A Review of Theoretical and ExperimentalResults"
U.S. NavyDavid Taylor Model Basin
(Naval Ship Research and Development Center)132. Report 1607 - April 1962 by Donald L. Blount;
"Resistance Characteristics of a 70 Foot HydrofoilMissile Range Patrol Boat"
0Iu01. THURrON AIRAfI CORPOAflTON REPOR NO. 6,M2DORT, m o "UJNK DATE. .
ISu 129
I U. S. Navy
David Taylor Model Basin(Naval Ship Research and Devel.opment Cen~er)
133. Report 1676 - January 1963 by Ficken anda Lebay;"Zxperimental Determination of the Forces on Super-cavitatint Hydrofeils w4th Tntornal Ventilation"
134. Report 1723 - August 1963 by Nathan K. Bales;"A Method for Predicting the Probable Number and Severityof Collisions Between Foilborne Craft and Floating Debris"
135. Report 1801 - December 1963 by Jerome Feldman;"Experimental Investigation of Near Surface HydrodynamicForce Coefficients for a Systematic Series of Tee Hydro-foils, DTMB Series HF-i"
136. Report 1778- October 1965 by Wilburn and Haller;"Experimental Measurements of the Steady Lift, Drag andMoment on Surface-Piercing Struts"
137. Report 2160 - March 1966 by Eugene P. Clement;"The Development of Efficient Hull Forms for HydrofoilBoats"
U.S. NavyU.S. Naval Air Test Center, Patuxent River, Maryland
138. "Hydrodynamics Manual," Flight Test Division - May 1958,by R.N. deCalles
139. Tech Report FT2121-35R-65 - 21 July 1965 byLCDR Nicholas J, Vagianos;"Evaluation of the Hydrodynamic Characteristics of theJRF-5G Hydrofoil Seaplane"
U.S. NavyU.S. Naval Ordnance Test Station
14o. NOTS TP 2346 NAVORD Report 6606 - 19 October 1959 byT.G. Lang; "Base Vented Hydrofoils"
U.S. NavyOffice of Naval Research
141. Contract No. N62558-2896 Task No. NR.062-287 by J.K. Lunde
and H.A.A. Walderhaug;"Surface Piercing Hydrofoils with Self Adjusting Incidenceand Shoek Absorbers"
mhomL,_ _ THUWTM CRAFT COGPORATION NgpalIT N9. 6912Bow &qNPNNONE Da~ ATE_
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11. S. NavyNaval Ship R & D Center, Washington, D.C.
1142. Report No. 211214 - June 1967 by George Springaton, Jr.;
"Generalize(' Hydrodynamic Loading Functlons for Bare andFaired Cables in Two-Dimensional Steady State CableConf igurations"
Papers
143. Journal of Ship Research, Vol. No. 4 pp 5-13, byH. Norman Abramson and Wen-Hwa Chu;"A Discussion of the Flutter of Submerged Hydrofoils"
144. Journal of Ship Research, Vol. No. 3, pp 20-27 byWen-Hwa Chu and H. Norman Abramson;"Effect of the Free Surface on the Flutter of SubmergedHydrofoils"
145. Journal of the American Society of Naval Engineers - May 1959by CMDR S.R. Heller, Jr. USN and H. Norman Abramson;"Hydroelasticity: A New Naval Science"
146. Am. Inst. of Aeronautics and Astronautics, Paper No. 68-4721 May 1968 by E. Yates, NASA Langley Res. Center;"Flutter Prediction at Low Mass Density Ratios withApplication to the Finite-Span Noncavitating Hydrofoil."
147. Society of Naval. Architects and Marine EngineersHydrofoil Symposium, 1965 Spring Meeting'
148. Am. Society of Mech. Engineers, 10 May 1962 by D.L. Stevens;"Flying on Hydrofoils"
149. Journal of Hydronautics Vol. 4, No. 1, January 1970 byP. Crimi;"Experimental Study of the Effects of Sweep on HydrofoilLoading and Cavitation"
STHURSTON AIRGRAFT CORPORATION R~PORT No. 6912oN_' _ _ _ "Ma DATE
