NACA RM L9D01 Preliminary Wind-tunnel Investigation at High-subsonic Speeds of Planing-tail,...

7/27/2019 NACA RM L9D01 Preliminary Wind-tunnel Investigation at High-subsonic Speeds of Planing-tail, Blended, And Airfoil-Forebody Swept Hulls

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RESEARCH MEMORANDUMPRCEUMINARY WIND-TUNNEL NVESTIGATION AT EIGH-SUBSONIC

SPEEDS O F PLANING-TAIL,BLENDED, ANDAIR,FOIL-FOREBODY SWEPT HULLSBy J o y . Riebe and Richard G. MacLeod

Langiqy Aeronautical LaboratoryLangley Air Force Bilse, Va.

.SSfftCATION CANCELLED

MITTEEUNCLASSIFIEO


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NACA RM LgmlNATI ONAL KCNTSORY COMMlTTEZ FOR AERONAUTICS

' By J o b M. Ri ebe and Ri chard G. MxIeodSUMMARY

A prel i mnary i nve8t i gat i cm m d e n the Langley hi gh- speed7- by 10- f oot tunnel to determne the hi gh- subsoni c aerodynamc cham%teri st i c8 of three di f f erent typesf f l w- boa t h u l l : namely, apl ani ng- tai l bul l , 8 bl m dedhul l , and an ai rf oi l - f orebody s w e p t h u l l .For coarparati veurposes a body of revol ut i on r epr esenht i ve of thef usel age of mamodern hi gh- speed airplane w a ~ lso i ncl uded. All theh u l l and fuselage data presentednclude the f orces nd moments of athi n w h g mept back 51.3O at theea- edge. The models weretested as r ef l ecti on- pl aneal f - mdel s on th e si de w a l l of t h e tunnel .Mach nunlers ranged from 0.48 to 0.%. "

The resul ts of the i nvesti gat i on, whi chr e consi dered quEtl f tati ve,showed agreel nent 88 to rel at i ve hul l ef f i ci ency w threvioualy reportedIdw-speed i nvesti gat i one of larger-scale model s. The drag- coef f i ci entvar i at i on and pi tchi ng- moment - coef f i ci ent var i at i on w th Machluniberf or the h u l l s and wing w e r e si ml ar to those of the fuselage and wing;thus, theproblem of desi gni ng a hi gh- speed seapl anelll probabl y bevery l i tt l e di f f erant eroaynamically f rom t hat f t h e landplane.

Because of t h e requi rements for i ncreased range and speed i n f l yi ngbwt s, an i nvesti gat i on of the aerodynamc character i st i csf flying-boat hul l s s af fected. by h u l l Umensi ons and hull ahape i e bei ngconducted at the Ungleg Aeronaut i cal I aboratorr . The resul t s of severa lphases of thi s i nvest i st i on atow speed a r e given in ref erences 1 o 4.. The corntenpl ated desi- of hi &-speed seaplanes has resul ted i nanextensi on of t h e i nves-t i gat i onto hi gh- acbeoni c Bkchumbere. The high-speed aerodynamc character i st i cs ofhi gh- l ength- beeprat i o hul l der i vedf r omref erence 1 have been presanted i n ref erence.


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I -i t ~. -

2 - " . NACA RM LgmlThe present i nvest i gat i onaa made to determne the hi gh- subsoni caeroi i ynmc character i st i csf two of the most -promsi ngf the h u l l s

of thelow-speed i nvesti gat i ons: a pl ani ng- tai l hul l ( ref erence),and an ai r foi l - forebody swept-hull (ref erence 4) A hul l bl ended intothe wing with generous f ai r i ng, whi ch i l l be refemed. t os the "blendedhul l , " a l m i l a r t o a hull devel oped' by t h e Comol i dated V u l W Ai rcraf tCorporat i on was also t e s t ed Inorder t o make a more compl ete coaerageof possible hull t nes for hi gh- speed water-based ai rcraft . For compar-ison purpome, , a body of revol ut i on representat i ve ofhe fuselage of amodern hi gh- speeda i rp lane was inc.luded. All the hull and f usel age datgpresented i ncl ude the forcesnd -moments of a thin wlng swept back1.3a t the leading edge. The modele were r ef l ect i F- pl qe half-models teetedon the si dewall of the tunnel; these data are consi dered qual i tat i ve.

SYMBOLS

The resul ts ofhe te&e are presented as st andard NACA coef f i ci entsof f orces and momnt s. Pitching-momen.t"coeffFcienta are gi ven about thel ocat i on ( w i n g 25 percent M.A.C. ) e h m I n f i gures to 5.The data are re fe r red to t he uind &xes which a re a eystemof axeshavi ng th e or i gi n at the centerf moment s shown i n figures 1 to 5 . TheX-axis 1s i n the pl aneof symmet ry of the model and '18 p a r a l l e l to thetunnel f ree- st reamir f l o w . The Z-ax l e is in the plane of symmstry ofthe model and is perpenAi cul ar to the X- a x i s ; the Y - a x i s i a mutual l yperpendi cul ar t o tha X- axi - s"andZaxi e. Ths posi t i vedi mct i ons of thew nd axes are shcwn i n figure 6.The coef f i ci ent=and sy~ i bo l sa re defined as f ol l ows:

CDc, pi tchi ng- mamentoef f i ci ent

iwice pitching moment of.semlspan mdel aboutssac


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NACA RM Lgml 3E wing mean ae-c chord (M.A. C ), 0.279 f ootv f ree- st reamvelocfty, f ee t persecondP ~ E Sensi ty of ai r, slugs per cubi c f oota angle of at t ack of wing chord line, degreesi i nci dence of wing chord l ine w t h respect to hul l base Une orfuselage center l i n eR Reynold6 nmiber, based .onwing mean aerodynamc chord (PE/P)Mb %Wce Wing span of semfspan model, 0.79 f o o tP vi scosi tycoef f i ci ent ,sl ugsper foot-secondC l ocal wing chard, eet

TESTSTest Condi t i ons

The test s were maden t he E i d e - w a I J . ref l ecti on pl anef the Langleyhi gh- speed 7- by 10- f oot tunnel. The ref l ect i on pl ane i s l ocated about3 i nches out f r omt he tunnel wa l l (fig. 1) n order o place the modeloutsi de of h e tunnel-wall boundary layer . The aerodynamc f orces ndmoments on the model were. nasa su red with an el ectr i cal st rai n- gage bal ancewhi ch was sealed i n a cof i tai ner 0 ~ 1h e tunnel si de w a U i n order toprevent ai r f l owaround t h e mode frdm the teat sec t ion to the outsidet e s t chaniber. Each d e l . was fitted w th a l - i n c h p l a t e at t he laneOP sgmmet ry (end pate, f i gs. 1 to 4) to min im ize a i r f o i l ci r cdat i ont hat mght develop throu& the sma l l . gap whi ch separatedhe model f romt h e ref l ect i qn plane. Because the plane of symnetry of a mdw ng-fuselage cani bfnat i on actss an end pl ate, o exposed end pl ate wasneceasary f orhe st reami ne body- w ngcombl nat i m (fi g. 5) A d lSy~. ~~t r i calnd plate was used f or th e wi ng- dme condi t i on and a Blllallroot f ai ri ng6 Used i n addi t i ono a8sure good f l owat the wing leadingedge. The roo t f ai r i ng consi sted of hal f round body f ai red i nto hewin@ and the end p l a t e ( f i ge 1)

16

The aerodynamc character i st i cs were determnedhrougb a Machnuniber range from 0.48 to 0.99 and through a l imi ted angle-of attack


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4range between -lo and 4 The var ia t ion of tes t Reynolds n W e r withh c h zlumber f o r average test cmdi t ione is presented in f igur e 7. TheReynolds nuniber i s based on t he wing mean aerodynamic chord and wascomputed by u8e of a turbulence factor of un ity . The degree ofturbulence ofri;he tunnel is not- known but i s believed t o be smallbecause of the large cont rac t ion ra t io of the tunnel.

CorrectionsNo jet-boundary, bloc king , or buoyancy co rr ec tio ns have been

applied t o the data because of the small s i z e of the model as congaredwith he size of the tunnel t e s t s ec ti on . The da ta were corr ecte d forthe tare drag of the end p la t e when present. The corrections weredetermined from unpublished data that give the effect of end-platesiz e and shape on the end-plate drag. These da ta were obtained forend plate s alon e and do not, there fore, account fo r th e effe'ct ofinduced f low over. he end plate caused by the w i n g o r hull as the casemay be .

The p lan ing - t a i l hu l l (hn&ey tank d e l 2-), t h e streamlineboQ, and the s w e p t - h u (Langley tank m o d e l 237-6 SB ) had the sameproport ions .as the large low-speed test--modelaof references 2, 3 , and 4,respectively. Offsets fo r the ref lect ion-plane W-models can be deter-mined fram the reference.s by rrmltip1yin.g by t h e r a t i o OFhe lengths ofthe reflection-plane models t o t h e law-speed models. Over-all d imns iansf o r the hal f - hul l and fuselage models incorporated on the l e f t wingpanel of a 5 L 3 O sweptback wing a re presented i n f igu re s 2 t o 5 . Theswept h u l l was also tes ted with an extended leading edge which may benecessary on a f u l l - s d e water-based arphne i n order t o a l l e v i a t ethe s tr uct ura l problem of at taching t he swept wing to the eueyt hul l .Offsets f o r the extended leading edge of the swept hull, ( f ig . 4 ) aregiven-in t ab le I. The blended. hull was similar t o a configuration underdevelopment by the Carvsolidated Vu lteeAfrcraftrCorporation. Offsetsf o r the blended hull are given i n t ab le II. This configuration willrequire a s t ep (see f i g . 2) fo r sa ti sf ac to ry hydrodynamic performance.For these tests tho s tep was i n t h e retracted position. The h u l l ,fuselage; and wing dimensions represent scale models of' 3b,'OOO-pounda i rp lanes wi th wing loadings of about 34 pounds per square foo t .

The volume^, Burface mew , f ron ta l areas, and side areas for thecomplete huUe and fwelage are presented in t ab le 111.


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NACA RM LgmlThe h u l l used i n determining the voluma and areas of the blended.nodel was ar b i t ra r i l y consfdered as that p o ~ i o nnclosed by an exten-s ion of th e dead rise t o the upper w i n g surPace 88 shown i n s t a t i o n A,f igu re 2.

5

The 51.30 sweptback w i n g used i n this investig3tfcm had an aspec tr a t i o of 2.92, .a taper r a t i o of about 0. 5, and an'NACA 651-012 airfoilse ct io n perpendicuLar t o t h e 50-percent-chord line. The WFng incidencewas s e t a t Oo on almodels except for one t e s t a t 40 CHI the ewept hullt o f i n d the efjrect of wing incidence. The wing waa constructed ofbery llium copper and the half-modele were [email protected].

The drag and p i t c h i n g - n n t c o e f f i c i e n t s of the hulls and fuselagep lo t t ed against Mch rider &re $resented i n figure 9 for U e s f a t tackranging from -10 o 4 t h e drag, Ist, and pitching-moment coefficientsf o r several modifi+tions of the swept-hull model a t 2O angle of a t t a ckare presented in figure 10. Figure LL e v e s the drag-coeff ic ient mi-a t io n and pitching-momant-ccefficient va r i a t ion with angle of a t t a ck a tlvkLch nlmibers of 0.80 and 0.95 for t h e blended hul l and the s t reaml ineb e . Figure 1 2 presents the aer-c c h a rac te r is t ic s of th e planing-tail h u l l i n p i t c h a t a m c h n W e r of app ra ima te ly 0.90. A l l the h u l land fuselage data presented. include th e f orces and moments of th e 51.3sweptback wing.

Although the drag coef ficien te do not campare di re ct ly ineudebecause of limitations of this reflection-plane setup, the values a r e i nqua l i t a t ive ajpeement with previously reported inve6tie;ations (references 2and 4) made a t low speed of large-scale models. For exanrple, a t 2O ang leof a t t a ck if g . 9 (c ) ) t he drag of the streamline b d y w as less than thatof the p lan ing - t a i l h u l l and the drag of the swept h u l l was less thantha t o f Ghe streamline body, which agrees w i t h the r e l a t i v e hull e f f f -cianc ies of references 2 and 4. The U e r olume ( t a b l e I I I ) of theswept h u l l accounted l a r g e l y for i t s lower drag. No comparison withpast work could be made f o r t h e blended h u l l because it m a o t tea tedi n the low-speed Investigation.

Very l i t t l e change in drag co ef fi ci en t occurred with Mach numberup to 0.90 f o r angles of a t t a ck ranging frcm-10 o 2O f o r most of thecon f igu ra t ions t e s t ed ( f ig8 . 9 and 10); however, a r ap id bc rea se i ndrag coe f f i c i en t began fo r the h u l l s above 0.90 Mach nmber. The st&of the drag r ise f o r the streamline body w as deleyed to a e l igh t ly


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6 - NACA RM Lgmlhigher Mach nmher, about 0.93, and the a t e of increase wa8 lees thanthat of the h u e .

A drsg r i s e similar t o that of the wing alone W&B ind ica ted f o rthe w e p t h u l l (figs. 9( c ) and 10) with th0 wbg-root fair-. Thewing-root fairing was a l s o u89d for the wing-done candikian ( f ig . 9 ( c ) )became . t h e wing-alone dreg r i s e w i t hou t the roo t . . fa ir in g occurredsocmer and wae grea te r than expected according t o previous tes ts ofs i m i l a r Mngs . It wa8 f e l t that the adverse effects an d rag wereprobably caused a8 a'result of end-platemisalinamant.Since thisend-plate candit im would not be present on a complete wing, it mi&t,therefore, be expected tha t the ewept-hull canfiguration incorporatingth6 wing-root fa ir in g more nearly repr eaep ts t h e awe& h u l l than theconfigurat ion xi thout th e f a i r ing .

Increasing the wing incidence t o bo on the swept hull increaa edthe drag coeff ic ient over that of the Oo incidence canfiguration through-ou t th e Mach number range t e s t ed and resu l ted in a drag rise a t - a owerMachnumber, 0.83 ( f i g . 10). However, on a complete model the drag r i s emay occur la t e r because of the probable limitaticm of the setup for theswept hull without the wing-root fairing, a8 mentimed e ar li er . Extendingthe h u l l leading edge ( f i g . 4) resu l ted 'i n an increase in drag coef f i -c i e n t throughout the M a c h number range'but ffected the drag r i s e 0d.ys l i g t l t l y .

Very l i t t l e v a r i a t i a n in pitching-moment coefficient occurred withMachnumber f o r t he hulls o r fuaelage a t th e angles of a t t a ck t e s t ed .The l i f t strain gage waB not operating througho ut moet of the preeent -investigation; however, It i s believed that the varia ticm of l i f tcoef f ic ien t w i t h Mach number f o r a l l the hul l s and fLiselage would besimilar to the change shm i n f i v e 10.Theminimum dr ag co ef fi ci en t a t high Mach numbers f o r the streamline-body and blended-hull configurations occurred near Oo ang le of a t t ack( f i g . 11). The drag coe f f i c i en t fo r the plan ing- ta i l hull ( f i g . 12) was

a l a0 minimum n e a r . - OO eng le of a t tack and was l e s s steep in-varrlatian withang le of a t t a ck than e i the r the atreamline body o r blended h u l l , probablyre su l t ing f r o m thB amaller beam of. the p lan ing- ta i l hull. Longitudinals t a b i l i t y a8 shownby the pitching-mament curves of f igure 11W&Binherent i n the vim-fuselage ccmibination. The blended hull W&B neu-t r a l l y s t ab le i n the positive angle-of-attack range at-25 percent me811aerodgnamfc chord, th e ce nt er of moments fo r th e pr es en e- te ste . O n l gmall changes i n l ang i tud ina l s t ab i l i t y with Mach nmber were noted f o rthe fuselage and blended-hullconfiguratiana. The longitudinal s t a b i l i t ya t a Mach number of 0.9 of the plan ing- ta i l h u l l ( f i g . 12 ) i e about the8- a8 that of the blended hull a t Mach numbers of 0.8 and 0.95 ( f i g . 11).I,


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NACA RM Lgml - , 7

The resu l t s o f the p re se nt h u l l i n v e s t i s t i a n , using ref lec t ion-planehalf-models, show quaUtative agreement as t o r e l a t i v e hull ef f ic iencywith previously reported low-spsed inv esti g% tion eof Large-scale models.The drag- coeffic ient vaziatio n and pitching-mmnt-coeff icient v a r i a t i o nwith m c h n&er fo r the h u l l s an3 x d n g were s a t i s f a c t o r y i n - t h a t dragr i s e was delayed t o high-subsonic Wch nunibere and there WBB very l i t t l echange i n pi tc hi ng moment with m c h nuniber. These c o e f f i c i e n t v a r i a t i o n sf o r the h u l l s and wing were similar t o t h e c o e f f i c i e n t v a r i a t i o n s of thefuselage sand wing; t hu s, th e problem of designing a high-speed seaplanewill probably be very little different aerodynamically from t h a t of thelandplane.Langley Aeronautical L&oratOryNat ional Advisory Comfittee fo r AeranauticsLangley Air Porce Base, Va.

1. Yatea, Campbell C. , nd Riebe, John M. : Effec t of Length-Beam R a t i oon th e Aerodynmc Characteristics of F l y i n g - B o a t Hulls. NACAmT 1305, 1947.2. Riebe, John M. , nd Naeseth, Rodger L. . AeroQnmic Charac te r i s t i c sof Three Deep-Step Planing-Tail Flying-Boat E d h . NACA RM L&7,1948.3 . Riebe, John M., and Naeseth, Rodger L.: Aerodynamic Characteristic6

' of a Refined Deep-Step Plening-Tall Flying-Boat H u l l with V a r i o u sForebody and Afterbody Shapes. NACA RM L&?Ol, 1948.4. Raeseth, Rodger L., and MacLeod, Richard G- : Aerodynamic Character- .i a t i c s of a n Airfoil-Farebody Swept Flying-Boat H u l l with a Wingand Tail Swept Back 51.3O a t the Leading Edge. NACA RM LgF08,

19495. Riebe, John M, and Naeseth, Rodger L.: High-speed Wind-TurmelInves t iga t ion of a plying-Boat H u l l with H i g h Length-Beam Ratio.NACA RM L m 8 , 1948.


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0.19.eg.39.49.59.e.79.@LC9.991.191.W1.99l.31.79l-998.192.398.73a.79

2.w3.193.393.733.793.994.u4-394-73c79

rarh * -ba0.41.k?.M.bl.40.3.*.J.n.36.?A.39.P

.a5.08.u

I.*

.P.ca.16.lg.2?


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. .I

1MalmJlns,0.20

0-1 3.TI.51.01.5

2.02.53.0k . 03.9

5. 07.06.0

8.08. 5

10.09.0L1.0.L9.0a.79


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mal RM Lgml

-e n t e r of m o m e n t s , -25M.A.C.I"- wing-alone'6 end plate L''ef lect ion p lane

I

3 8R e f l e c t i o n p l a n e

Figure 1.- Arrangement of the wall reflection plane in t h e Langley. hi&-epeed 7- by l s f o o t tunnel; wing alone.-


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. .. .. . . .

. . . . . . ." .. . ..


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- .90""-4 I IE .."._ " -"- 14.37"_IF PF l w e 3. - Linea of reflectlowplane d e l of planb@aIl hu l l ."


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3"r 1

enter of moments,.25 MAC

I"


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I "16 - Maximum radius,.83"

Typical section

15.00" \

5.42"1.91" Center of moments,25 MAC

.C.-.-.-. ,-.-. - "-I

'Wing root sectionFigure 5.- LIneo of stremiline-body r e f lec t lopp lane &el..I

.


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Ff@;ure 6.-.Wind-~txes. Pqait ive d i r e c t h m o f . forces, moments, andangles axe indicated by arrows.-.


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2

I

0.4 a 5 .6 .7 .0 .9 I,0

Mach number, M


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.. . . .


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8 I


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.. .

.

PN


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. . .. . . . .


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4 I

. .. .

( c ) x e n d e a hull.Figure 8.- Continued.-.


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b

(a ) S t r e a m l h w .Figure 8.- Concluded.-. . . . . . . . .


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m a RM L gm l

.I

0

4

.04

-02

0

II I a Streamline body

. 5 .6 .? -8 .9 1.0Mach n u m b e r , M(a ) a = -1 .

Ffgure 9.- Variation with BLch number of tb e drag coefficient andpitch-ment coefficfent fo r 8everaI hull t ypes and aetreamline body wfth 8 51,3O meptback wing.-


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28 NACA RM L g w l

. I

0

4

.04

.02

0.5 .6 .7 .8 .9 I.o

M a c h n u m b e r , M(b) CL = oo.


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NACA RM L9Do1

- 0EQ)E1c 4g.-e

.5 .6 .8 .9 I 0Mach number , M

(c) a = 2 .Figure 9.- Continued.


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.

ImEz32

I .-a

8..

. I

0

:I

.04

.o20

.5 .6

o Streamline bodyA Blended hull

7 .8 .9 I .oMach number , M

(a ) a = 4O.Figure 9.- Concluded. .


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c

mcA RM Lgm1

0 Swept hu l l with extended leading edgeSwept hullA Swept hull, I = 4 O0 wept hull mth wing mot fairing


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32 ~ C AM ~ 9 ~ 0 1

.I

0

rl

.04

.02

0

CONFIDENTIAL

M Model. .80 lended hull.80 treamline body -------01-.95 Streamline body---,95 lended hull ----

-2 0 2 4 6A n g l e o f at tack ,= , deg

Figure 11.- Aerodynamic ch&racterist&cs in pitch of a blended h u l l modeland a stremilhe bo&y with a 51.3 eweptback w i n g at hhch llumbers 0.80and 0.95. -


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HACA RM LgDOl 33

.

0

-I

72

.04

p2

0-2 0 2 4

A ng le o f a t t a c k , q d e g

.2

0

72

Figure 12.- Aerodynamic- ch ax ac te ri st ic s of p k i n g - t a i l hull w l t h a51.3O Bweptback w i n g i n pitch; M FcT 0.90.


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NACA RM L9D01 Preliminary Wind-tunnel Investigation at High-subsonic Speeds of Planing-tail,...

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