Large-scale V/STOL testing

NASA TM X* 73,231

NASA TECHNICAL

MEMORANDUM

LARGE-SCALE V/STOL TESTING

David G. Koenig, Thomas N. Aiken, Kiyoshi Aoyng'

Ames Research Center

Moffett Field, Calif. 94035

nnd

Michael D. Fnlorski

Aines Directornte, USAAMRDL

Ames Research Center

Moffett Field, Calif, 9403:

( N A S A - T M - X - 7 3231) L A R G E - S C A L E V/STOL

N77-23OG 1

T E S T I N G ( E A S A ) 3 6 p HC A 0 2 / N P 8 0 1 CSCL 01C

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3. Raclpientt* btelop No. 2. Governmmt Accarlon No.

1. Woport No.

NASA TM 2 - 7 3 , 2 3 1

6. Rcport Oslo 4. Titlo and Suhlltlo

LARGE-SCALE V/STOL TESTING

8. Parforming Organlretlan &do 0. Periormlng Orpnlzmlion Roport No.

7. AuthorC1

David G. Koenig,h Thomas N. Aiken,* Kiyoshl Aoyagi*

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and Ml..cchaol D , l!alarslti**

to, Work Unlt No.

0, Performing Orgsnit~tton Nams md Addrsu 505-10-41

Wmes Research Center, NASA and

11. Conlnct or Grant No.

h*Ames D i r e c t o r a t e , USAAMIU)L Ames Research Center, Moffett F i e l d , CA 94035 13, Typa of Report ond Period Covercd 12, Sponrorlng Agency Namr and Address Technical Memorandum National Aeronautics and Space Administration, 14. Sponsoring Awncy &do

Washington, D , C . 20546 and U . S . Army A i r Mobility

R&D Laboratory, Moffett F i e l d . C a l i f . 94035

16. Supplumantary Notes 16. Abstract S e v e r a l f a c e t 8 o f l a r g e - s c a l e t e s t i n g o f V/STOL a i r c r a f t c o n f i g u r a t i o n s are discussed with p a r t i c u l a r emphasis on t e s t experience i n t h e A m e s 40- by 80-Foot Wind Tunnel. E x a r i p l e ~ of powered-lift t e a t prngrame a r e preeented i n o r d e r t o i l l u s t r a t e r r a d e o f f s c o n f r o n t i n g t h e planner of V/STOL t e s t p r o g r a m . It is i n d i c a t e d t h a t l a r g e - s c a l e V/STOL wind-tunnel t e s t i n g can

sometimes compete with small-scale t e s t i n g i n t h e effort required ( o v e r a l l

t e s t time) and program c o s t a because of t h e p o s s i b i l i t y of conducting a

number of d i f f e r e n t t e s t s with a s i n g l e l a r g e - s c a l e model where s e v e r a l

small-scale models would be reql~ired. The b e n e f i t s of both high- o r full-

s c a l e Reynolda numbers, more deta,tled c o n f i g u r a t i o n s i m u l a t i o n , and number and t y p s of onboard measurements i n c r e a s e r a p i d l y w i t h s c a l e . Planning must be more d e t a i l e d a t l a r g e s c a l e j.n order t o balance t h e t r a d e - o f f s between

the increased c o s t s , as number n f measurements and model c o n f i g u r a t i o n

v a r i a b l e s i n c r e a s e and t h e b e n d f i t s of l a r g e r aTounts of information coming o u t of one test.

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17. Kay Words isu~gestod by Author $ 1 ) 18. Dirtrlbution Stutcment A i r c r a f t Unlimited Design T e s t i n g

STAR Category - 05

21. No. of Pages 20. Security Clorsif. (of this pgel 22. ~ r i c c * 19. Security Uauif, (of thls roportl $ 3 . 2 5 U n c l a s s i f i e d U n c l a s s i f i e d 'For solo by tho Nationol Tochnical Informnuon Sorvlco, Springflpld. Vlrginia 221 61 LAROE-SCALE V/STOL TESTING D o v i d C. Koenlg," Thomas N, ALkcn,** rind KiyatihL Avyngi* hmes Rcscnrcli Cnntor, NASA, M o Efct t P l c l d , ClilI farnitr und Michael D, Fnlarekl U . S . A r m y Aviation Systems Command Air M o b i l i t y RbU 1,rtloratory h m e ~ 1)irecturatc Ametr Hevenrch Ccntar, Moffett F i e l d , C a l i f o r n i a h b a t r n c t FX = a x i a l farce L = l i f t Scverc' 'ncets of large-scole t e s t i n g of V/STOL a i r c r a f t configurations a r e discussed with particu- 11 = 11u1nbur O F l i f t i n g elements l n r ampllusis on tust exporionco i n tlrc Amos 40- by PNL = percoivcd noiso lovul, dU 80-Foot Iflr I Tunnel. Exan~plcs of powered-lift t e s t l', = irtmosplreric pressure programs u J ~n+esented i n o r d e r to i l l u s t r n t c t r s d e - of f s c o n f r o t ~ t i n g the planner o f V/STOL t e s t programs.

P7 = t o t a l pressure I t i s indicated t h a t l a r g e - s c a l e V/S'rOL wind-tunnel t e s t i n g can sometimes compete with smull-scale t o s t - q = dynamic pressure i n g i n tho e f f o r t r e q u i r e d (overall t e s t time) and S = wing area program costs because o f t h e p o s s i b i l i t y o f conduct- i n g n lrumber of d i f f e r o n t t e s t s with a s i n g l e large- = t o t a l t h r u s t (fan u t a = oo)/q(nd2/1) T , s c a l e modcl where s e v e r a l small-scale models would V = airspeed, m/sec (knots) be r e q u i r e d . The b e n e f i t s of both h i g h - o r f u l l - s c a l e Keynolds numbers, more d e t a i l e d c o n f i g u r a t i o n = j e t v e l o c i t y , m/scc ( f t / s e c ) Vj sirnulatior., and number end type of onboard measuru- a = arlglc of uttack ments increase r a p i d l y with s c a l e . Planning must be more d e t a i l e d a t l a r g e s c a l e i n o r d e r t o balance fiy = d e f l e c t o r vane s e t t i n g t h e t r a d e - o f f s between t h e incronsed c o s t s , us numbor 6 = f l a p deflecti.on o f moasurcmolrts and model confj guration vorinbles i n c r e a s e and the b e n e f i t s o f l a r g e r amounts o f i n - I. I n t r o d u c t i o n formation coming o u t o f one t c s t .

Development of V/STOL a i r c r a f t is becoming Nomenclature more dependent on large-score wind-tunnel t e s t pro- grams than has been tho case f o r the davalop~nent o f AE = nozzle a r e a conventionnl a i r c r a f t , I n t e r a c t i o n of t h e pawcr- p l a n t and the airframe introduccts udditional t e s t = n ( T I D , , / ~ ) ~ , a r e a oE powered l i f t i n g pnriuneters, and a n a l y t i c t o o l s i n t h e process o f AL areo; f u l l y expanded being developed t o handle t h e e f f e c t o f this i n t e - g r a t i o n have not y e t been proven, Because o f the

- nb2/4, momentum a r e a of a i r c r a f t

Am cornplcxity and c o s t s of some V/STOL models and t h e i r AN = nozzle area components as well a s c o s t s o f f l i g h t t e s t i n g , it i s f e l t t h a t l a r g e - s c a l e t e s t i n g a t low speed must = cross-"ctional a r e a of wind-tunnel t e s t AT become a more s i g n i f i c o n t p o r t o f a i r c r u f t devel- s e c t i o n opment. I t i s , t h e r e f o r e , tho o b j e c t i v e of t h i s b = wing span paper t o give t h e reader soar: i n s i g h t i n t o t h e major considerations nssociated with l a r g e - s c a l e V/STOL = width of t e s t s e c t i o n bT t c s ting.

CD = drog/qS The paper is divided i n t o two p a r t s : reasons Cd = discharge c o e f f i c i e n t f o r t e s t i n g a t l a r g e s c u l c , i . e . , s c a l e e f f e c t s , d e t a i l , and a c o u s t i c s ; and t e s t c o n s i d e r a t i o n s , i . e . , planning, s i z i n g , model constructiort, and operu- C , = pitching moment/qSc t i o n s , The p r e s e n t a t i o n makes use o f ns many ex- amples as possible from t = s t r e s u l t s and from ex- periences i n t e s t i n g l a r g e - s c a l e powered-lift Cv = velocity c o e f f i c i e n t models. Most of t h e examples a r e from programs a t = mean aerodynamic chord t h e Ames 40- by 80-Foot Wind Tunnel and t h e s t a t i c t e s t s i t e s nearby. I t i s f e l t , Ilowever, t h a t mony = diumeter o f l i f t i n g element DL of t h e considerntions discussed a r e a p p l i c a b l e t o d = fnn diameter o t h e r large-scale t e s t i n g h c i j i t i e s where powered models a r c involved.

*Research S c i e n t i s t , Member A I A A .

**Research S c i e n t i s t .

l I , _Hya-yon~_f_q~f,L_rpe-Scule T e s t i n g Strong sculu a f f e c t s had bocn notud i n p a s t in- v ~ ~ t i f i ~ t ~ u t l s of s l o t t e d f l a p configurutlons, hut 'Ihu rcilsorrs f o r t o s t i n g u t l u r y c s c u l c ilrc tliesc occurrcd p r i n ~ a r i l y vi t l i t h e power o f f . llcrc, many, but mucll o f the J u s t i f i r u t i o n can bc plucud wl t l i 11 bloutr Fli~p !iys tern, o w n though instrumenta- s i t h i n the o I ) J ~ ~ t i v o s of o b t ~ i ~ r i n g c l o s e t o f u l l - t i o n was completu t'or uatli models, u t l e a s t toh'ilrd s e u l c llc!.nolds t\umbcrs, r e q u i r c m u ~ ~ t s f o r d e t n i led meeting the objvct ivcs o f ttrc r e s l ~ c c t i v o t e s t s , r c p ~ ~ c s c n t s t i o n o f mode 1 confl guruti ons, and tho tlicrc s t i 11 NUS not e~rougli docun~cntlttlon t o slroti possibility o f o b t a i n i n g n Lurge v a r i e t y o f illfor- 1 c 1 1 y the differelices i n l i f t occurred, TIM p r l n c i - mat ion from one model, including n o i s e e v n l u a t i o n , pal complications wore probably tlie s c n l c c f f c c t l'u milril~ll:c tho c o s t s and time required for t c s t - or1 t h e r c a c t t o n of t h e j e t with tlic f l n p systom, Lng botlr large- rind smnll-scalc morlcls, these rca- cornbitled w i t h tlic use o f two d i f f e r e n t power sys- JOnS rnust be c l o r e l y cvulurrtcd. 'fb help in cvnl- toms fol- tho two nladels. Those e f f c c t s und sirnilnr utrtjan, b r i e f oxurnl~los follow.

ones have t o bc separated and wcll defined i f re- s L I t s from smull-sculc powcred ~nodels ure t o be S c a l c Eft'ecg uscd .

In muclr of tlle work t h a t tuns bccn dono in urrtc- Even though with small s i z c I t i s d i f f i c u l t t o Igzing s c a l e ofFocts 011 the c h u r u c t c r i s t i c s of l i f t - provide s u f f i c i e n t l r i s t r u ~ n c n t a t j on t o docun~ent propulsion s!.stelns, there has been d i f f i c u l t y I n sep- s c n l e e f f e c t s , i t i s c o n t i n u a l l y bcing attcml~tcd.

a r a t l n g the combined e f f c c t s of ~ ; ~ i t r g from one modcl One program where good c o r r e l a t i o n bctwaari lurgc and t e s t i n s t a l l i l t i o n t o nnotlwr model and t e s t in- nl~d small s c a l e was obtoirrcd was i n t h e dc\+elopment s t a l lntion. For V/STOL u i r c r u f t model t e s t i n g , t h i s o f tllc Advanced l l a r r i c r and i s tllc s u b j s c t of trqa is o continual problem becuuse of tlrc s t r o n g e f f e c t o t l ~ c r papers i n t h i s c o n f ~ r e n c c . ~ 1 ~ TLI a c c r t u i n of the simulated propulsion systcm on t1.c acrodyrlamic e x t e n t , t h a t case was more straightforward ill t h a t characteristics involved. Exiimplzs o f comparisons f u l l - s c a l e r e s u l t s were used as v e r l f i c a t l o n of tllc which i n d i c a t e such s c a l e o f f c c t s a r e presented i n small-scale r e s u l t s i n o r d e r t o quantiFy such F i g s . I , 2 , and 3 f o r components of i i f t i n g systems things us f l a p l i f t lncrcn~cnts and iritcll c o n t r o l , ~ h l c h a r e do~umented i n Refs. 1 und 2, and unpub- Purtllcrmi 742, the f lup nnd propulsion systems were l i s h e d data, r e s p e c t i v e l y , Even f o r thesc cor- not complctel!. i n t e g r a t e d as was tllc caso f o r tllc relations thuro are always questions: How ac- exturnnl b l o a ~ ~ - f i a i i (EDF) models u f i:lg. 4 , and c u r a t e are t h e s u r f a c e contours f o r t h e i n l e t t e s t s 7 small-scale f l a p pc~formancc was not influenced 11)' \$as the g r i t l a r g e enough snd upplicd f a r enough small dlcfcrenccs in t h e simulntior~ of the engiilc forward on t h e s l u t f o r the case i n F i g , 37 But e f f l u x .

f o r t e s t i n g complote powercd-lift c o n f i g u r a t i o n s , Jocu~nenting such things as s i m i l a r i t y i n contour, Mode 1 De tai 1- s i m i l ~ r i t ! ~ i n flow conditions, o r d e f l e c t i o n s under load can be an o r d e r of magnitude more d i f f i c u l t .

Vrc comparison i n s l a t e f f c c t i v c n e s s shown i n Fig, 3 is believed t o dcmonstrutc the e f f e c t of Problems I n c o r r e l a t i n g t c s t r e s u l t s f o r corn- Ileynolds number; however, t h e r e i s a chance that p l e t e configurations may be i l l u s t r a t e d by the in- s l a t d e t a i l s such os t h e mechanicnl reprcsentntion v e s t i g a t i o n of an e x t e r n a l l y blown f l o p S W L con- o f the s l a t nose and wiper p l a t e thickness may f i g u r a t i o n completed by N A S A 4 years ago. 3 r " Two hove on c f f e c t on s l a t performance.

modcls were b u i l t , t h e l a r g e r being s i x timcs t h e s i z e of the s m a l l e r , with t e s t s being performed i n For powered-lift modeis, t h e r e have been cases t h e Ames JO- by 80-Foot Wind Tunnel and t h e Lairgley of e x t o r ~ l a l l y blown f l n p t e s t s r ~ h e r c bracket thick- V/STOL Tunnet, respectively. The t e s t i n s t a l l u - ness and placement have a f f e c t e d f l a p p o s i t i o n and t i o n s a r c shown i n P i g . 4 . The small modcl was s l o t gap optimiration. Another exsrnple of the e f f e c t powered by e j e c t o r propulsion s i m u l a t o r s and the o f brackets occurred i n t h e development o f the N A S A The small l a r g e one by JTl5D-I turbofan engines.

C8A f l i g h t t e s t v e h i c l e . 7 The a i r c r a f t was a C7A model i s shown mounted within the l i n e r i n s t a l l c d Buffalo modified t o incorporntu d i r e c t t h r u s t and a i n t h e 15- by 2 2 - f t t e s t s e c t i o n of t h e V/STOL t h r u s t augmentor f l a p . During t h e development, a tunnel t o simulate t h e 40- by 8 0 - f t t e s t s e c t i o n .

0 . 7 s c a l e model o f t h e nugrnentor f l a p was s t a t i - Although the e s s e n t i a l purpose was n o t t o look a t c a l l y t e s t e d , and t h e r e s u l t s a r e reported i n Ref.

Reynolds numbers or s i z e e f f e c t s as both wind- 8 , A s e c t i o n of t h o augmentor i s shown i n F i g , 6 .

tunnel programs had o t h e r s p e c i f i c o b j e c t i v e s , the Early i n the t e s t s , t h e upper ? a r t o r shroud wns c f f e c t of s c a l e \<as an i n c i d e n t a l r e s u l t o f thc held on by t h e turnbuckles t o illlow udjustnrent of program. As can be seen by the three-component As the design of the s l o t s f o r optimization runs.

d a t a of Fig. 5, the comparison i n t h e performance a i r c r a f t proceeded, u f i n n l attachment plan, adapt- o f thc two models was less than s a t i s f a c t o r y . Wi?h a b l e t o the a i r p l a n e , was developed, and t h e s t a t i c t h e power o f f , t h e l i f t was l e s s f o r t h e l a r g e mod- model was t c s t c d with several configurations of e l ; with the power on, the l i f t was g r e a t e r , This t h e s e b r a c k e t s . I t was found t h a t refinement o f was the case even though the f l a p geometry was the design improved t h e performance o f the system s i m i l a r f o r tho two cases, i n d i c a t i n g a Reynolds by 12%, based on t h e t h r u s t of t h e primary nozzle.

number e f f e c t i n f l a p e f f e c t i v e n e s s f o r both power The width of the turnbuckles was the same as t h a t o f f and on o r d i f f e r e n t propulsion e f f e c t s .

of the n i r c r a f t brackets s o t h a t , i n t h i s c a s e , it was evident t h a t t h e l a r g c - s c a l e model was needed t o confidently e v a l u a t e a l l the d e t a i l s of the f l a p mounting s t r u c t u r e .

Variety of Information t l a r r a c k , J. P.. H a l l , L , P . , and k i r k , J. V . , " F u l l - k a l e I n v e s t i g a t i o n of the Law-Speed Aero- Lnrge-scale models can provide a wider range dynamic C h a r a c t e r i s t i c s of the F-1118 A i r c r a f t , " i n t h e t ) ~ . c i , m f meirsurcmcnts obtained i n one t e s t N A S A Ames Working Paper 249, S e p t , 1969, than s n ; ~ I ' , . I c models. Fleasurements poss i b lc u s i n g lurgc ~ r c d o l s ura i l l u s t r : ~ t u d ill tlic upper l e f t t l ~ u t tlrc 40- by 8 0 - f t wlnd tunncl wuli uscd f o r tlrc o f Fig. 7 f o r rl complcto u i r c r ~ ~ f ' t ~ o r ~ f l g u r l t t i o ~ .

lnrgc-scalu tcstti u t $S70/11rl and n t y l ~ l c a l V/S'FOL hbst o f t l r c s ~ cut1 110 IIIU&!C i l t snlul 1 sc111o , tltlt tllcy tunncl of 5 m Ijy 8 n l , such a s u t Lutrgley o r Lock- would probably 1.cr1uire scvernl nioduls. L l s i a ~ snal- hucd, wus usvlf f o r s ~ n u l l - s c a l e t e s t s a t $IFiu/hr.

l c r sculu ~nodclu, oltllor cortrpulreiitu o r coml~loto 'Ilrcrc vu kuus reprcsurrt d i r a c t c o s t s pl us ovcrhcad , u i r c r a f t co~rfigurrrt ions, tlio t e s t i tottlr OII tho r l g h t 'The co~npurison can otkly bo q u u l i t a t t v c s i n c e hourly o f 1:l R. 7 a r c pous r blo , hcous t l c s t u d i o s rcyui rc r u t c e c;ltl vury f ron~ orru fuci 1 l ty t o unotlrer', und, s p e c i a l ~nodcl design und t e s t i n g consldcrat iotrs w11:~rcus w o [Issumo tlrat Irotlr s t a t L C land wind-tunrrol w h i ~ t r , fnr hoth lirrgc ilnd s n ~ u l l s c a l e , I I I U ~ require c o s t s urc the sumu, s t a t i c t e s t r u t e s i ~ r c likely scllarotc tos t s . Mcusuring noisc o f l urge-sctrlc t o bc lowur. 'So f u r t h e r simp1 i f y the t.oml)rrrison, n~odels i s discussed in llcf. 8 , and sj>cclul toclr- c o s t of ~ n a t u r i a l s , powor l i l a ~ i t s , cqull~ment, model rolmir, pcr diem rlrilt t r a v a l cxpcnscs wcrc t ~ o g l c c t c d .

rriqucs f o r u c o r ~ s t l c resourclr 111 tulincls nrc t r o a t c d i n Ilof. 11). I f ucoustlcs curl be studied In the This docs not i n v n l i d a t e the com[rurison sitrcu, gerr- same t e s t s , I~orrever, sigtrificnnt c o s t s l ~ v i n g s o r a l l y , t l ~ c c t ~ u l l ~ ~ ~ ~ c n t nnd power p l a n t s nre alrcndy should IIQ possiblu.

uvnilablc + n r irrcorporrltion i n t o tho nrodol and t e s t i a u t i l l l u t l o n , orld tlrc c o s t of i n s t a l l a t i o n r e f u r - For conrl~lctc a c o u s t i c moduls, t h e typical b l s h m ~ n t , o t c , is l e s s th1111 1 O b f totrrl program problems 11t smnll s c a l e contlnue t o bc such things COS t S .

a s s u p ~ ~ r e s s l o r i o f noise of ~ ~ r o p u l s i o n simulutors, Ili gh- frequency mcnsurcn~cnts, aird s imulntioti of do- [:or the l a r g o - s c a l e t c s t s , tlrcrc was orlo s t a t i c t a i l . A s s c a l e goes t o f u l l s i z e , noise moasurc- and one wind- tunnc l t c s t , 'I'lle smal I - s c a l e l~rogram mcnts i n t h c 40- b y 80-ft wind turlncl must bc mndc wr,s divided illto four s e t s with the componcnt nlodcls i n tlrc ncar Field. R U E . 11 doscribes ail empirLcl11 t e s t e d s t a t l c u l l y und the coml~lctc rnodols t e s t e d in tochniquc f o r c o r r e c t i n g r e s u l t s f o r trcar-ficld A supmary of the c o s t co~~~purisorr the wind tunnel.

u f f e c t s and compurcs j e t rroise rnonsuramcnts w i t l r i s prcsonted i l l P i g . I0 which shows tlrrrt t o t a l pro- f l i g h t t e s t s (Pig. 8 ) . Wind-tunnel and f l i g h t gram costs urc approxin~ately tlre same f o r the two measurements ugrccd w i t l ~ i t ~ 2 da. With t h i s program progranrs .

and othors sr~clr a s thut o f Ref. 12 f o r cstnblislr- ing the v a l i d i t y of wirrd-tunnel a c o u s t i c mcnsura- Ottlcr cuses i n which t c s t e f f o r t was orgarrized munts, s i x can bo usod t o good advantage to it) u $ l i g h t l y d i f f e r u n t wuy thatr the^ shociti ill simulate botlr d e t a i l i n tlre l c c a t i o n o f thc sensors Fig, 1 0 showed tlrut the r n l a t l v c c o s t s could vary and the complete a i r c r a f t c o l i f i g u r a t i o r ~ .

This wus a s much as 25%, p a r t i c u l n r l y when u comj)oncnt t e s t t r u e for t h e l a r g c SICL model shown i n Vig, 4 . 1 3 ~t such ns tlrnt f o r u t h r u s t d e f l e c t o r was nddcd t o somewlrat s m a l l t r s c a l e f a r j e t n o i s e s t u d i e s S U C ~ I tlrc lurgo-scale t c s t program, tiowever, regurdless as that shown ill Pig. 9 , 1 ' 4 s i z c of tlrc i n s t a l l u t i o n of t h i s and the ~ ) r c v i o u s ly mentioned qua1 i Fications helped t o r e f i n e the survcy o f tlic noise f i e l d o f h o t o f the study, i t seems evident t h a t t h e l a r g e - s c a l e high-velocity j e t s a t several frecstream v e l o c i t i e s . c o s t s do not havc t o be much lnorc than thosc required f o r small-sculc t e s t s i f the large-sculc Costs model is designed t o combine several d i f Percnt Once t h e need f o r large-scala t c s t s has been types a f moasurelnonts during a s i n g l e s e r i e s of formulatod, limits on thc use of sucli t c s t s havc t e s t s . I f t h i s can be progranmod, tlrc large-scale o f t c n been placed because of high c o s t estimates advarltngos of Irigl~ Rcytlolds number, Strodla1 number, f o r the proposcd programs. Tlrc u l t c r n u t i v e s a r e d e t a i l of gcnlnctry, and meusuremont accuracy can b e t o use smal?ar models and do more t c s t i n g of a i r - obtaincd while c o s t i n g l i t t l e more thun tlrc cquiv- c r u f t components. Since, f o r t h e l a t t e r cnsc, tile n l c n t small-scale t e s t i n g e f f o r t , lnck of l a r g o - s c a l e t c s t r c s u I t s might jcopi~rdlzc p r e d i c t i o n s o f a i r c r a f t Plight c l ~ a r a c t c r i s t i c s , 111. Tcst Considerations it was f e l t t h a t o study o f cornparutivc c o s t s of large- and s m a l l - s c a l e t e s t progranls was j u s t i f i c d .

Even thouglr the cos t 5 o f smnll- itnd l a r g e - s c ~ le Cases were s t u d i e d which were e i t h e r completely t c s t i n g ciln be e q u i v a l e n t , a major p r ~ b l e m i s the largc s c a l o o r complotcly small s c u l e but had com- shortage of l a r g c t c s t f a c i l i t i e s . Thc wind tunnels mon f i n u l o b j e c t i v e s . Orre of t h e s e cases is de- capable of accepting some complete n i r c r a f t , located scribed below and i s bascd on t h e a u t h o r ' s cxper- i n the United S t a t e s , a r e l i s t e d i n 'ruble 1.

iunce w i t 1 1 t c s t programs of n l a r g e v a r i e t y of a i r c r a f t configurations. The r e s u l t s must trc con- sidered approximutc because of t h c following: d i f - Tablc 1 Wind- tunnel locations f i c u l t y i n - e v a l u a t i n g the impact o f compute;- controlled machining and forming on model making; Maxi m u m speed, F a c i l l t y , m ( f t ) wide v a r i a t i o n Ln c o s t s of t h e s m a l l e r wind tun- in/sec (knots) n e l s ; no d i s t i n c t i o n in labor r a t e s f o r d i f f e r e n t s k i l l s ; v a r i a t i o n s i n possible conrbinatfons of the 9 , 1 , 1 8 . 3 x e o ) (Langleyl 51 r e l a t i v e e f f o r t used irl componcnt and comaloto configuratioii t e s t i n g , 1 2 , 2 ~ 2 4 . 4 ( 4 0 ~ 8 0 ) [ M e s ) 9 2 [ 1 8 0 , r i l l b c 3 0 0 ) 24.4 x 36.6 (30 x 120) (Ames, 51 (100) A comparison was mirde of c o s t s of two t c s t design i n progress) programs, one a t largc s c a l e und orie o t small s c n l e , . - each producing t h e sumo v a r i e t y of information as l i s t c d For tkrc small model i n F i g . 7. I t was as- sumed t h a t a l l tho smnll models were s t i l l largc Each o f these f a c i l i t i e s has open s t a t i c t c s t s i t e s enough t o j u s t i f y use nE the t c s t d a t a d i r e c t l y to ncarby so t h a t models can be transported bctwccn p r e d i c t s t a l l aild maximum f l a p performance; i . c . . f a c i l i t i e s without complcte disassembly. The f o l - no additional t e s t i n g time was nssumcd ncccssnry lowing discussion w i l l c o n s i d c ~ t e s t s i n and near f o r g r i t checks and flow s t u d i c s t o d e t a i l any the 40- by 8 0 - f t wind tunncl, but much of the d i s - local Flow scparatiorr. I t was a l s o assumed cussiorr could be up111 ied t o planning t e s t programs 0 ) t)t)rrPwi ng o r ~ C ' R S ~ I I ~ ~ cqu Ll)nlo11 t u~ld mod01 purts :ti otlrcr test f u c i l l t ~ c s . In rucclrt ycurs tlrorc l~.:vu I ~ O C I I two very a r t ivo open-fiald t u s t si t u s a t wllcrc ~ > o s s thlc .

Llu:~surcrnunt~ t o be mrrdc urc m u J ~ r I\IIIVS wlriclt liuvc bcorr used For 110tIr tus t l ~ ~ g of modul 1) l ~\rririnfi I tulrrs .

]:or V/S'I'OI, witrd- tunnel tvs t lng u t 11s comlrlctc. iii rcruft krr 111 rcrtlft corrlponcnts 11s well 1;rrgu sciilc, tho typuu o f nlousurernunts a r c nlurly UIIJ could illclrrdc ill1 o r romo O F fhu fol l~wirig f ~ i rrtru roll F l gurir t l uns , t o s t : Stnbi l l t y and control 1) ExtrcrLc~rcc w i t h rccullt V/S'IUL t e s t tJrrrgrilnls in the 40- Iry 80- f t wir~d tun~lol lii~s rlruwn t l i ; ~ t to luducu costs urtd tcetlrrg tlnlc, advtilrccd [)l;i~rtifr~g and nrguni ziktioti cannot hc over e a ~ ~ l r u s i zed. Scr- vice u r ~ n n t :utLotrs, c o n t r a c t o r s , 111rd N A S A o f f i r o s m i r u t bc ill1 coordinated and briufcd. 1;iguru 11 5 1 Surfncc prcssuro rncasurcmcn t s on 1 1 1 1 sl~owt\ t h e orjii~nl ~ u t i o n of throc recurrt p r o j e c t s 111 com~loncn ts ordcr of i ~ ~ t r c z , s i n g cost und c h t e n t o f or~t1111 z u t i o n , 'Ilrey rellrescnt oxampleb OF 1) ;In in-lruuse rcscarclr Aroustlc s t u d i o s , trcur and f a r Eiuld project (Fig. l l n ) , 2 ) u j o i n t scrvicc-NASA 11.6 U.

progrimr (Pig. 1 lb) , und 3) a ~ P I ' V I C C - O ~ ~ C I I ~ O L I

H) Wak- surveys, downw:ist~, sidewush rlevdlopmcr~t progrum sulrportcd by NASA (17ig. l l c ) .

lrlow strrvcys ncur tuenal walls t o D ) P r o j e c t 1 t e s t r e s u l t s o r e rcportcd i n l1uPs. 15 s v u l u a t e wall cFfeets nnd lo. This vss un iirtolrrully monngcd, bilsic rusearch p r o j c c t w i t 1 1 the o b j e c t i v c of studying s t a b i l i t y and c o n t r o l , high angle-of-attuck ctrnr-

111 S t r u c t u r a l . > t i c ulld dyrlilmic lnndillg

a c t o r i s t i c s through ~ I I B s t a l l , urrd a c o u s t i c s . Pxoj- 12) A i r c r u f t systems clrccks o c t managcmcnt came from t h e Ames Large-Sctllc Aero- dynamics Branch ( U A I l ) with both an cnginc and an A p r i n c i p a l problem i n progriim mnnugcmcnt is t o eirf-amc mnnufilcturer a c t i n g a s c o n ~ u l t a n t s . Final avoid a t t c m p t i i ~ g s o many mcilsirromonta t!iut tho raporting Wits done by tho LSAH.

primary gouls ot? t h e axlicriment a r c jeopordizcd through complex equipmclrt malfunction, but, a t the Project 2 t c s t r e s u l t s uro r c p o r t c d i n Rcfs.

same timc, to ttrke Full ildvtlt~tngc o f tlrc t c s t i s - 17, I S , ~rnd 1 9 . T l ~ i s rdns a Navy-NAEA j o i n t l y Funded s t u l l a t i o n , anJ t e s t i n g time.

program, mo~~agcd by NASA, with t h c o b j e c t i v e of obtaining s t a t i c ( i n and out o f gmucd e f f e c t ) md Model S i z i n g and Constructi un wind-tuneel J a t o f o r loads, s t a b i l i t y nrrd c o n t r o l , and performance. The model was h e a v i l y instru- Uurirlg t h e e a r l y dcvcloplnent s t a g e of powercd- mented t o document propulsion and e x t e r n a l s u r f a c e l i f t a i r c r a f t , components such as d e f l e c t o r s , Iircssurcs. The t e s t mnagement came from the Antes t h r u s t r e v e r s e r s , OF blown flaps can be studied, A i r c r a f t P r o j e c t Offico, with t h o LSAB serving a s but e v e n t u a l l y , t h e complcto l i f t i n g sys tell1 must iidvisors. 'rlre airframe contructor sulrportcd tho be roprcsontcd making t e s t s orr complotc a i r c r a f t t e s t s w i t 1 1 design, t e s t support, d a t a a n a l y s i s , confi guratione e s s e n t i a l . In a i t l l c r case, consitl- and reporting, e r a t l o n of c o s t ~neuns r e s o r t i n g t o simplifying model c o n s t r u c t i o n , adapting rnodcl s i z c t o oxistirlg Project 3 t e s t r e s u l t s a r e reported i n Ref. 6 , surplus engincs, o r minimizing test configuration This was Navy-fundad w i t h t e s t management coming clionges .

j o i n t l y from t h e LSAB, tlre c o n t r a c t o r , and t h e The rnodel was equipped p r i m a r i l y f o r f u l l - Navy.

Sizing s c a l e s t a b i l i t y , control, and performance checks with the instrumentation required t o documcnt power For model s c a l e s which makc f u l l t ~ s e of t h e s e t t i n g s together with u few loads. The c o s t o f capacity of tlre 40- by 8 0 - f t wind tunnel, our ex- tho model was un o r d c r of rnag~ritude h i g h e r than t h e perience has been t h a t s i z e is d i c t n t c d by a v a i l - foregoing p r o j c c r r be cause the model combinud n a b l e energy sources sucll as compressed a i r capacity fuselage P l i g h t s t r u c t u r e with t h e Rolls Royce and e l e c t r i c a l motor and gas turbino sizes a v a i l - F402-R-402 engine and a b o i l e r p l a t e wing-flap a b l e . As w i l l bo discussed, the s i z e of gus t u r - system. In a d d i t i o n , since the t e s t s wore p a r t bine engines which hove been developed f o r business of on a i r c r a f t development program on n t i g h t jet a i r c r a f t odapts well t o model s c a l e s of 0 . 3 t o it was highly " v i s i b l e , " and a l a r g c schedule, 0.7. For l a r g e r models, tlrere is n jump i n t h r u s t number o f c o n t r o c t o r personnel were r e q u i r ~ d to t o t h e 10,000 c l a s s which w i l l force t h e norody- support the o p e r a t i o n of t h e t e s t s and c o r r e l a t e nnmic s i z e Ilmits and r e s u l t i n l a r g e wall i n t e r - t c s t r e s u l t s on a d a i l y b a s i s .

ference e f f e c t s . The estimation o f these e f f e c t s then becomes v i t a l . Reference 20 r e l a t e s a i r c r a f t The t e s t programs of both F i g s . I l b and l l c aird wind-tunnel geometry t o model-tunnel si zing proved not only t o include and r e q u i r e extensive parameters i n o r d e r t o e s t a b l i s h t e n t a t i v e s i z i n g coordination between groups, but they were a153 c r i t e r i a f o r V/STOL wind-tunnel t e s t i n g . Correla- expensive. This was t r u e i n s p i t c of t h e i r use o f t i o n p l o t s from t h a t reference ore presented i n scmf d l the f o l Lowing considerations. tliglr c o s t s F i g . 12 and hnve been updated with the modcls o f can iometimos be c u t by the following: 1) use of Refs. h , 15, and 19. The l i n e s have been somel~hat boiler. p l a t e construction f o r modcls, 2) cnrcfr11 a r b i t r a r i l y drawn i n t h e f i g u r e t o represent guide- evaluation o f t r a d e - o f f s i n complexity and c o s t , l i n e s o f good wind-tunriel f l i g h t corro1ation. The 3) use o f increased tolerances where a t a l l pos- r ~ a l l e f f c c t s f o r t h e l a r g c configurations and f o r s i b l e , 4 ) use of a n a l y t i c methods and algorithms decelcrotilrg f l i g l ~ t can be s i g n i f i c a n t a s shown i n i n planning the t e s t procedure, 5) coordinntior~ wit11 Rcfs. ? t nnd 2 2 , and t h e ranges of Fig. 1 2 might small-scslo programs t o minimize d u p l i c a t i o n , an3 well b e lowered f o r thesc cases. tlowcver, i t i s in Vig. 17. Sincc ilro lardel wus t o bc uscd t o invcutigntu r r l r c r t ~ f t .s',.uhlllty, c o n t r o l , n ~ t d s t u l l c h i l r a c t c r i s t i e?i , I t wus docidud tltst tho wui girt o f t h e itt~cul l e c0~11d be ~ulljrortod fro111 below wi tlr nn Currorltly, the ,nost jrcuct l c u l o f tlrc ulrcrj:y ovors I rut1 111111 9 t r l'f pylon I I ~ I ~ I I I . Il~ithor t111iti L I S ~ sources uvullublc for 410- by 80-ft wind-tur~nul modal ux[~enr; l vo slrol 1 r~iount t o tn; r~imi zo ovcrsl 1 usc is tlie smull t u r b o j e t o r turbofa11 c n g i l ~ v . 'Iko

nnccl l e r~idtlr , the o~rgirioa wurc movad nutltuutd or)

ortgir~ev uvni l a b l o a r c sliowri iri Fig. 13 togcthcr tlic w l ~ r ~ t o m u ~ n t a i n u rctluirod 1otrgt.h o f cxllosod with tlrc o p c m t i n g p:!Imunlotcr.s f o r maxlmram corrt in- wing l c a d l n ~ edge betwean thc ~ r u c o l l c s utrd t11c Amu~ nttcmpts t o maintain 11 s u f - \lous pei~Porrnn~~ce. f~tsclllgc, Irr tcrnls of percunt spun, t h i s wus Less c o l ~ f f p u r u t i o n r ttbun 1% s1)nrr F t i r t l t ~ r out 011 tlre wing. For tlris f i c i e n t rlumbor of ouclr t o poncr modcl Tlrcsc angi!res, lluving t'rom four to s l x onglnos. cusu , t h c moximurn rrozz l c pressure r r ~ t i o rm.! optln~um plus otlrcr gos porter s o u r c e s , hsvc been plncud or1 duct pcrformuncu wore not nocdod, so tlra ir~tcrnrrl the thrust-pl.ussuru r a t i o mup of I:ig, 1 4 . llte 'r58 ~ r o z z l c corrtours wcrc not c r i t i c i l l us long rrs t h e und ,185 uro uscd to d r i v c t l ~ c LP576 arrd Ll:336 t i p - s u r f r ~ c c s wccc ~:o~~tirruous und smootll irr a scroilmwiso d i r e c t i o n . To cnsc tlris s i t u u t i o r t , t h o nozzle was drive11 funs, rcspectivcly [0,91 m I 3 Ft) diumutcrj.

mnde o+vcrly long t o reduce curvuturc. 'I'hi s rnndo Tlro LF376 funs rrrcrc used in tlrc nrodcl slronlr i n F i g .

15 ( t h e model uscd i n :hc progrunl of P L g , l l b ) .

i t possll>ls t o uuo scgn~cntcd, rvuldrjd c o n s t r u c t i o n Ilro d115 hus a l s o been used ns a l i f t originc orIeritcd of both t h e h o t nrid cold nozzle ducts with oxtarnnl i n a v o r t i c u l thrusting p o s i t l o n f o r thc program formcrs ds showl~. 'Rro forwurd skin wus r o l l o d s h c e t s t o o l with ucccss p n n c l s pluccd to casu of itof, ?3. 11) ndditlon, t h i s c ~ r g i n c Irns driven tlra t u r b i n e s of modified Viper errginus f o r uhicll s u r v i c l n g nrtd engine chocks (no compo:urd curvas) , t h e compressor output i s used t o power blourr f l a p Ilic s k i n on ttru n o z r l c hud t o lruvo a corqow~d modcls such as t h a t reported i n Rcf . 22 or f o r corvuturc, but i t was covcring tho c?iltcr duct and the blown semispan i n s t a l l u t i o ~ i sllown i r r Pig, 16. could bc f i b e r g l a s s , '[?re i n l e t uus spun-fornled f o r prevj ous t e s t progrums ur~d wus rcndi ly udolrtud t o A d d i t i o ~ l a l sources o f energy suctr iis higlr- tlie tracalle frunlework ttnd cowling. h f t c r t h e f i r s t

t c s t , t h e lowcr lluccl l c contour wilr ri~odificd oco-

pressure a i r and e l e c t r i c powor hnvc bccn consid- nomicrilly by adding fonm nnd f i b e r g l u s s f o r a l l four ered only as auxiIinry power f o r lurgo-scnlc models, n n c e l l c s . Ilr i s irlvolrod ~ppfo~lrmiltcly 100 man- except f o r tfre e l e c t r i c motors d r i v i n g rotary- wing o r props1 lor-driven madoli; , As tho higli- liours.

prossure u i r sourco cupucity is increased a t tlre 'l't~e sccolrd exnnaplc i s tlrut of thc complete wind tunnel, it could be p r n c t i c o l energy sortrco VTOL. rrretllod used f o r t h e program of Fig. 11I1. Ilie f o r medium-sized s t n t i c o r dynamically s l m i l u r nrodel is shown i n Pi[;. I 8 (during its c o t ~ s t r u c t ~ o n } models, 12-in, -diamntcr t i p - d r i v e n fun i n s t ; i l l u - tians, and boundttry-layer c o n t r o l ;3LC) systotl~s for rind i:i F i g . 15 ( f u l l y complctod!. Thruc T58'5 Target cajlacity f o r tlic n i r r~oadcd t o powcr t h e LF336 fur& wcrc Irouscd i n t h e l a r g e - s c a l e mnodcls.

fuselage und ingcstud a i r fronr t h c two s i d r i n l e t s supply is 32 kg/scc (70 Ib/sec) a t 2000 psi milximum (one i s sliswn i n s t a l l e d ) . Ilic hot ducting was we1 1 with a continuous r a t i n g o f 1 1 kg/sec (25 l b / s e c ) .

insulated and bay cooling wtls an c s s o n t i o l p a r t of For information on a v a i l a b l e e l e c t r i c motors and tlic design, making i t p o s s i b l e t o form most of tlic maximum load, t h e reador slrould consult Rcf. 21, conipound s u r f a c c s From Fiberglass, p n r t i c u l u r l y Tho foregoing has beet) a very b r i e f discussiotr t h e si~nulfitcd cirnopi and . ' c i n l e t s . Most of tlru o f t h e p r a c t i c n l c o n s t r a i n t on sizirrg large-sculc surFaccs wero defined by ~ ! 8 - t o l / l - i n , s t e e l r i h a o r btrlkttcads, ])recut t o n computed curvuturc f o r models, tho porvor p l a n t , A major need is f o r a small o r medium-siztld, trigh-hypilss-ratio t u r b o h n t h a t p u r t i c u l a r c r o s s s c c t i o n and welded i n place It is hoped o r n p r n c t i c a l sctierne t o ;imulltte it, t o a base frumtrwork. I n hot uroas, stritrgcrs were t h a t f u r t h e r develupmcnt o f t h e business j e t w i l l i n s t u l l e d , nrrd s t e e l s k i n wus plug-wcldcd or The c l o s e s t to t h i s screwed t o t h e s e formers which bccame atr ititcgral bring about such an englnc, Dctcrmining tho nvnilrrbllity o f $ a r t of t h o s t r u c t u r o . In cool a r e a s , foul11 rind is t h e LP376.

f i b c r g l ~ ~ s s wore i n s t n l l c d botwccn tllc forrmru. 3 3 6 these and o t h e r possibilities, such ns t h e cngincs wing and Flaps had a s t e a l s p a r and were covorcd l i s t e d i n F i g s . 13 nnd 14, a s well a s e l e c t r i c a l with rrood urrd u s i n g l e luycr of f l b c r g l n s s . S.11al1- nnd high-prossure ui-r sources, becomes an esserl- t o l e r a n c e nrcus were Ireld t o the o u t e r wing, flaps, t i n 1 c o n s i d c r n t i a n in tho plnnning of a prolrosed and i n l o t s . Construction setup time was consid- powured-lift program.

e r a b l y reduced by increasing tolcranccs i n o t h e r arcns whore p o s s i b l e .

Construction A very s i g n i f i c a n t note m t r s t be made about Exporicncc i n c o n s t r u c t i o r ~ of l a r g e - s c i ~ l c mod- locilting instrumentation on modcls such a s t h a t j u s t e l s has shown t h a t , f o r most cuses, s o - c a l l e d doscribcd. Tltc scnnivalvcs arid rnisccl Jancous t r a n s - b o i l e r p l a t e construction i s ndcquutc and no more d u r 9 r s which a r c located crl the model must be ac- oxpens i v e for P given a i r c r a f t configuration than f o r $ma1 l c r .nodal5 requiring rnaclrining, advanced c c s s i b l o and compatible with cooling requirements, For t h e uhove model, i t was d i f f i c u l t to find a casting techniques, und many mnn-hours of f i n i s h - coo! a r c a i n which to i n s t a l l tlicsc u n i t s (an a r e a ing. fiowever, t o p r o f i t from t h e advantages of c o r ~ t r a l l y located t o minimize pressurc tubing " b o i l e r p l n t i ~ ~ g , " expansive forming, c a s t i n g or l e n g t h ] . The finill p o s i t i o n was bctwccn t h e o u t e r machining a r c not u t i l i z e d , u ~ l l c s s t h c s c methods wing rind tho giis generator i n l e t d u c t .

The prob- a r e iibsolutely required t o ~ c c u r a t c l y simulate Icm was r e c e n t l y made s i g l r i f i c a n t when on o n b o ~ r d perforn~ance i terns such as i n l e t , s l o t s , o r wing data a c q u i s i t i o n system was mndu optional f o r 40- leading-edge contours. To i l l u s t r a t e trade-offs.

by 80- f t willd-tunnel modcis, This systcm requires oxamplee follow.

l o c a t i n g Kemotc Multiplexing D i s t r i b u t i o n Units (HMDUts) on o r near t h e modcl, preferably near t h e 'the housing f o r thc JTlSD used on the uppcr s ~ l r f a c e blown-fli~p (1ISU) modcl o f Ref, 15 is sllown scnnivnlves. Alttnugh use of tlic RHDU15 w i l l not tunnul s[r?cd L s ud)bi~teJ rn.11rl1111 l y , t h i s rc(iul I'US t ~ c ruc~rr I red, they n i l 1 yruatly rodrrcu Iiookul) tblid good coordltrir t i dl) botwuon the w l nd- t u n , ~ u l tind lrrosrurc chock t imo.

cnglnu ulrurtitorn [ur modcl c o n t r o l l u r ) , Irinos r a ~ ~ r o s c l j t i n ~ ltru wind-tunncl r h r r r u c t c r i s t i c s with ttic modcl out iI1.U 11150 S I I O W ~ I f o p T O ~ C ~ O I I C C . ' 1 9 1 ~ vrrl uuu o f At1 hero clrosuri to brucket tlru ot(:rl\*u lcrlt ' h e limited u v a i l u t ~ l i t y of large-sculc wlrrd wind- tunnel ~ l o l i t- chunye roquircd t o compcrrsutcl tunlluls mokos I t imlrorutivc t l r u t tlrc conljrl~tc t e s t ~WOccdurc cvolvc? from trudu-oft's kn tlllurcl t i lllu f o r thu tlrrus t rlrurrgo III tho t a s t soctiua. '111~ probloms with wind-tunrrel s 1 r u uru i l l u s t r u tcd by ib~rrl 11iodc1 c o m ~ ) l ~ x l t y S L I C ~ I US tlru ~rulntrar o f onbourd mcnsurcmc;its o r tlie ~rumbcr of conf i gurnt Ion vilr- tho lirrgc u i r ctrcultrtion tlmo OF 8U s c c f o r 60 i if.bloa. For jlowered- 1 l f t I)TOpfbmS, tt\c uXI)CIISU o f hrlots, a cormnonly usod t c s t u l r s p u ~ d f o r \I' OL t r a ~ r s l t i o n . In p r n c t i c c , i n a r d o r to bo rrvsrlrcd t h e modcl and j u s t i f i c u t l o n f o r s t i t r t i 11g thu pro- chat uirrpocd has stoppod varying, tlru tlmo takcn gram i n tho f i r s t p l r ~ c c soom t o b r i n g prcssorc from 1s ubout t w i c ~ thirt indicated f o r the 50- t o 60- a1 1 p a r t l c i p a n t s t o I~lcrouuu ttru nwlllror o f Illuosurc- knot rnngo, about 2 m i l l , the l u s t mlnutc is ~ ~ W I I -

murrtri a ~ r d t c s t virriubles . 'Ihe fa1 lowing conrmcrlts

c r u l l y consuared by fino ndjustruuats t o oirspood.

uru designud t o h e l p with judging tlia inapact of A computer-controlled spccd radjustmont trow b u l n ~ increasing con~ploxi t y 011 wi~id-tunnel t ime .

considerod f u r tlw new 40- by 80-Pt/BO- by 1 2 0 - f t FLgurd 19 shows tho r u t i o of t o t u l down timu t o s t powor s y s t e n ~ may ulimirrutc the need f o r t h i s l u t t c r pcriod o f udjustrnont, tlowcvor, i n s p i t e o f t o o n - s i t e time a s u functlon of tho number o f modcl d:onfigurutio~r vuriublos, 'Ihc v c r t i c a l s c u l c inl'uts from inodul powcr c o ~ i d i t i o n s , u n g t . ~ o f rrttuck, o r u i r temjloraturu, s u c l ~ a spoud coritro. systom is s l l d i n g s i n c e tire a c t u a l r u t i o cun depond on too marly f u c t o r s beyond our con tl'ol. A good tiumber w i l l s t j l l Illtvo d l f f i c u l ty ~ I I ruducing the timc f o r zero chongus with power o f f is 30 us u s t u r t . indicated i r t tho t'igurt* simply becuusr of tliu largo ?ha estimutions o r frlircd curves a r e busud an 350 v o l u ~ ~ ~ c o f u i r c i r c u l u t i n g i n tlra tuHlrc1, onbonrd moosuremonts. 'I'hc t o s t cuscs hove upproxi- mntcly t h i s number of mousuromcnts. Some of tire A miijor prol,lcm i n opernting with gns turbine r e s u l t s come from tlro uuthorls experiences and o r e enginus r e s u l t s from tlro lack of o p o s i t i v c vctb- q u u l i t a t i v o , but thu curves a r c p r i m a r i l y derived t i l u t i n g system and u p r a ~ t i c u l operating l i m i t o f Erom tho USD t e r t s , 1 5 l i f t - c r u i s e fan nrodcl t o s t s , l g 130°t: i l r the t c s t s c c t i o n . ,\s shown i n Fir:. 2 2 , ltnd augmentor wing t ~ s t u , ~ ~ 'I'hc e f f e c t o f jroiror is the use of gas tur1)ins engl~le; ~ ' o s u l t s i r r e curttiin maximum running time. After t h i s , t h e engines must showr. on the p l o t a t zero configuration chungos and should ha t y p i c a l o f thc penalty paid f o r en- be s h u t o f f , t h e uppropriutc doors opened, und tho gino maintenunce, timc required t o purge tho tun- tunnel run n t lor+ speed f o r purginp o r f o r reducing Currently, t h i s takes 20 min t o n e l of exhlrust gnscs, and cooling of tho a i r i n t h e uir temperature.

tunnel. Thc s t e e p e r slope with tllo F i r s t two con- 1 h r . To ruduce t h i s time, which is e s s o n t l a l l y f i g u r a t i o n changes r e f l e c t s the assumption thut l o s t f o r t e s t purposes, un attempt is uvuolly made t h e s e two a r c major chnnges (such as t a i l i n s t u l - t o s c l ~ e d u l c V/STOL t o s t i n g with engines i n t h e cool l n t i o n o r removal silbicll can take 2 t o 4 h t s in tllc months and/or r e s t r i c t i n g operntion t o evening und 40- by 80-ft wind t u n n e l ) , e a r l y morning hours. Note t h a t tho choice of power p l n n t and s i z i n g o f the model have a s t r o n g in- 1:igurc 20 shows t h e vnriotion i n timc required fluonco on t h i s time. Tlre problem w i l l c e r t a i n l y t o record each d n t n point tis a fullction of the num- be eliminated i n operating tho 80- by 120-Ft t e s t b o r o f onboard monsuromcnts. N o accounting i s s e c t i o n , made of power changes which a t times must bo made t o kcop up with chongcs i n tunnel a i r temperature In summary, tho major f a c t o r s t o consider i n attempting t o minimize wind-tutrncl time f o r l a r g e - and wlrich can oJd en udditional 30 s e c t o some These ninor t h r o t t l e adjustments con s c a l e V/SWL modcis a r e , t o n ccrtni.n c x t e n t , d a t a paints.

s i m i l a r t o thove o f o t h e r powered modols. In both usually be done during changes i n o t h e r s e t t i n g s such os angle of a t t a c k o r s i d e s l i p . I t has been cases, power nnd instrumentation c u l i b r a t i o n s should assumed t h u t t h e f i r s t 1-1/2 min c o n s i s t o f : be done p r i o r t o model t e s t i n g , model p a r t s should s e t t i n g tho t e s t conditions such RS angle of uttnck, bo f l t t c d , and run procodurus planned i n d e t a i l .

s i d e s l i p , o r powor; l e t t i n g the tunnel airspeed The mujor d i f f e r e n c e s appear i n operations where, f o r tho l a r g e r t u n n e l s , s e t t l i n g times u r c l a r g o ; -toady out; and recording the d a t a Ercm tho s c a l e f o r closed-return t u n n e l s , gos generator operation *tern. After n 12- t o 15-soc scanning p e r i o d , Another Foctor lrding with t h e model d a t a system is s t a r t e d . b r i n g s t h c need f o r purging time.

which has not boon mentioned i s t h a t tho l o g i s t i c s bough, ns t h e systom i t s e l f is r e f i n e d i n t h e .ure, tltc s l o p e o f t h e curve could decrease of making model churigcs i n t h e l a r g e r wind tunnels .ightly, t h e p e n a l t y i n t o s t i n g time becnuso o f u r c completely d i f f e r e n t s i n c e the model i s 15 t o anboord meusurcmonts is s i g n i f i c n n t enough t o war- 40 f t above t h e wind-tunnel f l o o r . To take advan- r a n t inclusion i n t h e i n i t i a l planning o f t h e pro- tage of thc l a r g e r s i z e i n order t o g a t many types I n a r r i v i n g a t the I-1/2-min period shown of d a t a , t h i s difFerence must Ire rccognizcd, und grum.

i n Fig. 20, it was assumed thiit any t h r u s t changes a c c e s s i b i l i t y problems must bc a n t i c i p a t e d a t the would be only chose required t o compensate f o r inception of t h e prograh.

tompcruturc changes, and tunnel powcr would hnve t o IV. Concluding Remarks bc changed i n small increments bctwccn d a t a p o i n t s .

1,nrge-scale V/STOL wind-tunnrl t e s t i n g r e s u l t s Figure 21 i l l u s t r n t e s the problems encountered i n b e n e f i t s of both high Reynolds numbers and more d e t a i l e d configuration simulation, and tho number i n estimating tho s e t t l i n g timc required a f t e r u und t j p e of p o s s i b l e onbonrd measurements increaso r a p i d t h r u s t o r d r a g change i s made i n t h e t c s t r a p i d l y with s c a l e . Large-scale t e s t i n g con some- s e c t i o n . The cross-hatched area r e p r e s e n t s a n as- times compete w i t h small-scnlc t e s t i n g i n t e r n s o f timate o f the minimum required timc, assuming t h u t tho e f f o r t required ( o v e r a l l t e s t time) and program wind-tunccl d r i v e power i s changed t o compensate c o s t s bccnuse of t h e p o s s i b i l i t y of conducting t h e t h r u s t change a t tho same time. Since the a number of d i f f e r e n t t e s t s t h a t would require 11Jdltiu11ul $rrrall-sc~ilc moduls. Plutrrritrg rnllst be I ~ l : n l a r e ~ I , E l . I), , Aikun, '1'. N,, Anyugi, K., more d c t u i l u d a t ltrrgo :o%clu itr order t o t\i~luncc

und Koonig, I). (i. , "Cunllrurison of Acoust LC! Cfrnr-

t llu trndc-of fs botwoorr t k c ilrcrutrsud c o s t a , as IIUIII- a c t u r l v t l c v of' Lurgc-Scalc Lludulv of Suvor111 Pro- bur uf inuuuilr.cmolrts unti sotlul c o t ~ f l p u r u t l o r ~ vur- p u l s i vu- l,i f t Currccllts ,'* J o r r r ~ ~ u l , of iiJrcruftS*, tclrlcu ~ I I C ~ C ' I I S U , JII$ thc $onof i ts of lurgor urnouats Vol. 1 2 , J u l y 1!175, pp. b00-(10cl.

of Lnformutloa comi~tg out of orru t u s t . To tlolp 111 uvalutrting tlruvo t r s d o - o f f s , tlcvuri~l ftrcots O F

llb,laock, C. J, , 1 t 5 t s t i c und Wlnd 'hmncl Noar-

l o r g o - s u ~ l o t u s t i n g hiivu buon ~ ~ r o s c l ~ c c d w l t l ~ p u r t i c - Iricld/l:ar-iliold J o t Naiso Fluuvurcmcnts franl Modul u l a r unllrlruuis on t o s t cxpuricnco I n thu Anion 40- by

Scula Singlc-Vtnw Ilusclino und Suppruasor Nozzlus ,'*

Hfl-ft Wlnd Tunncl . ~ a i ; u , $ o u x o Locations and U ~ t r 1 1 1 ) o l ~

Val, :: o f titic Frcc:I!?ld J o t Noisu Until, x u ~ a (X- 157913, S c p t . 1376. ,101, I T ; =jlrd S1)ccd liffllcts, N A S A CR- 137913, NoV. 197h.

lblort, K. W . , llSu~~~rnury o f tirrgc-Sc111a 'I'cs t s of

DuctuJ I;urrs," Paper 8 , Co~ifcruncc on V/STOL nt~d 151\oyagi, K , , Fularski , M. D . , und Kor*t~l g , U.

a ' l ~ l , A l r c r u f t , h c s ncscurclr C c ~ ~ t c r , hloffutt P i e l d , G . , I1Wilrd 'Turrncl lnvcs t i g u t ion o f a L~lrgo-Sctllu Ci11 J r, , lt)6(1, N A S A SP- 116.

U111>er $ur..~cc Blown-Flap 'I'rnnsport hloJo1 tlnving 'Two Engines," N A S A Tbi X-02,296, Aug. 1 9 7 3 .

"liickuy, U, 11. , l*V/SWL Aerodyaumicu: A lte-

vicw of tlru ? ' c c t ~ ~ r o l o g y , ~ ~ ACAAD Co~lfcruncc Prococd- I6~ocnig, 11. G , und Aoyogl I K , , wMuximunr Lift of Lngs 143, I1nl~cr 1, D c l f t , tho Nctherluods, 1073.

tlppcr Surface Blowing STOb A i r c r a f t with Swept IYings, t1 AIM Pu1)cr 75-868, Ilortford, Cenn., 1975.

3 ~ 0 y a g i , K., I:ulurski, b t , D . , und Koonig,)1. G., ilWt~~d-'f'u~rncl 111vcutiyatLon of n I,nrga-Scala 25 17~nmbusci, B . J . , Aoyugi, K . , und I{olls, L . S., Swept-Vliag J c t Tru~ivport Modcl w tll en External "Wind Tunnel Investigation o f a Lurgc-ScaIe Modcl Blowing 't'riplc-Slottcd ?lap," NASA, Tbl X-62,197, o f a I,ift/Cruisc Fan V/SlDI, Alrcrnft," NASA TM Nov, 1973, X-73,139, May 1976.

4Guntry, C. L., J r . , tlWind-Tun~~ol Invos?ign- l a ~ u m b u c c i , U, J . , Aoyugi, K . , anit RoIls, L. S . , '.Lon of an I n t o r n a l l y Blor+~t Flnp STUL t r a n s p o r t ItWiud Tunnol Invustigution o f u L u r ~ e - S c a l c Model Modcl Including UJI Invcstigntion of Will1 of u Lift/Cruiua Fun V/6M1. Alrcruft with Extendod N A S A 'FM X- 3009, Sept . 1'374. L i f t / C r u i s e N u c e l l a ~ ,*I N A S A 'l?4 X-73,lfi4, hug. 1976.

5 ~ i i l l o r , K . und Luccy, T. R. , tlThc AV-8D lying: g l l ~ i n d Tunnol drld Ground S t a t i c 1 1 ~ v c ~ t L g a t i o n Acrodynomic Concept and Uusignl8' AIM Paper 77-607, o f u Largo S c a l e bfodcl of n Lift/Cruisc Fan V/SI'OL Moffctt Field, C a l i f , . 1977.

Aircriift," N A S A CB-157916, Oct . 1876.

Gtlollingsworth, E. G., Aikcn, T. N,, and Huggct, 2°#ickey, D. li, and Cook, W . L., liCorrclation J . , l l V n l i d a t i ~ n o f AVB-U V/STOL C h a r e c t e r i e t i c s of of Wind Tunnel und Flight-Test Aerodynamic Data f o r 1:ull-Scnle S t a t i c and Wind-Tunnol ' r e s t s I t * AIAA F i v c V/STOL A i r c r a f t , " prcsvnted nt the Plight Pnpor 77-597, Moffctt Picld, C a l i f ., 1917.

Mochunics Panel Mooring o f AGAIlO, Romo, I t a l y , Oct.

1965.

7 ~ u i g l e y , t I . C, and Vomaskc, R . F., "Prelim- inary Results of Flight 'rests of t h e Augmentor-

z1l(ouniL, D. G. md C o r s i g l i a , V , I!. , 'lAcro-

Wing J e t SlUL Hoscurcli Alrcruft," S1'0L Tushnology dynamic C h n r a c t c r i s t i c a o f a Large Scala Flodol with Conferonce, Paper 20, he:; Research Centor, Moffett an U~\snopt Wing nnd Augmontcd Jet Flop," N A S A TN l:ield, Calif., 1972.

D-3610, June 19CU.

a ~ o r k o n a n , L), L . , Wi~~tormoycr, G. I:. , und

22flcyson, H. I t . , ',Rapid Estimation o f Wind Wright, F. L., " S t o t i c Tosts of il 0.7 Scale Aug- Tunrhel Corrections with Applicntion t o Wind Tunnel mentor Wing Flap for tEl~a Modified C-8A Airplane Scpt. 1971.

and M o d o l U ~ s i g n , ~ ' N A S A T N R-6416, 1971.

'Test Results ond A n i l l y ~ i s , * ~ N A S A CR-114315, 2 3 ~ o l h u r s t , II. H, and Kelly, M . h , , "Character- g ~ a l a r s k i , M. D. , Koenig, U. G. , und Sodcnnn, i s t i c s of TWO Largtt-Scnlo J e t - L i f t Propulsion

I*. T, , *lAspccts oE Investigating SML Noise Using

Systems," Conference on V/S'ML and SML A i r c m f t , Large Scille Wind Tunnel b i o d o l ~ , ~ ~ Canadian Aero- 1966, Ames Rcscurctr Center, bloffett f i e l d , C a l i f . , n a u t i c s and Spnce Journal, Vol. 19, Feb. 1973, N A S A SF-116.

pp. 61-69, z h * + ~ u i d c f o r Planning Invcstigntions i n tho Ames

lo~odermatr, P . T, , " I n s t r u m c n t ~ t i o n und Tccll-

40- by 80-1:oot Wind Tunnel," Arne5 Resonrcll Center, niqucs Eor Acoustic Research i n Wind T u n n ~ l s , ~ ~ 6 t h MoFfott Field, C a l i f . , June 1975.

~rrternutiorlal Congross on Instrumcntution i n Acro- space Simulation I : a c i l i t i c s , IELE Pub.,ication 75 ClHl 993 6 hES, 1975.

l i s t r o u t , F. C. and Atencio, A . , "Flight E f f e c t s on JT8U Engino J e t Noisc as Measured i n tho N A S A Ams 40- by 60-Foot Wind Tunnel," AIM Pnpcr 76-556, Palo Alto. C a l i f . , 1975.

1 2 ~ t c n c i o , A. Jr,, "The E f f e c t of Faword Speed on JR5 Engine Noisc from Suppressor Noeztcs us Measured in t h c NASA-Amcs 40- by 80-Foot Xind Tun- nel," NASA T N D-8426, Feb. lCJ77.

WING MOMENTUM AREA AATlO " \ $ \ \ 0 X V 3

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0 XC 142

A A X V 4 A

h h XV6A b h A V B B

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- 1 1 1 1 1 1 1 1 1 * - 1 I'

2 10 l o o imo in000

lb/ft2 I - ' t rrr~d molnunturi urnu . ; izin$:.

u l b XV 6A b AV 86 0 L/C 3 0 USB 4 DISK LOADING b) Wing span sizing.

P i g . 1 2 . Sizing pnramctcrs.

THRUST W P ~ / P o A" N ( ~ b ) kolsoc (Ihtooc) rn2 in?

* '

I-;-

'Zi2--Jj + * * j

I..., I . . , . . , . , . ,

k:dlk.p-.,%%p-, .... I., ,...*.... .i

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Small turbofan or turbojet engines nvclilnblc for use in largo-scale V/STOL testing.

Fig, 13 REFERENCE LINES WHERE: It) ESTIMATED F i g . 14 Summary of possible gas energy sources (continuous running limits unless otherwis.: noted).