NASA TECHNICAL NASA TM X* 73,231 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: (NASA-TM-X-7 3231) LARGE-SCALE V/STOL N77-23OG 1 TESTING (EASA) 36 p HC A02/NP 801 CSCL 01C . 1. Woport No. 2. Governmmt Accarlon No. 3. Raclpientt* btelop No. NASA TM 2-73,231 4. Titlo and Suhlltlo 6. Rcport Oslo LARGE-SCALE V/STOL TESTING 8. Parforming Organlretlan &do
7. AuthorC1 0. Periormlng Orpnlzmlion Roport No. David G. Koenig,h Thomas N. Aiken,* Kiyoshl Aoyagi* A-7002 and Ml..cchaol D , l!alarslti** to, Work Unlt No. 0, PerformingOrgsnit~tton Nams md Addrsu 505-10-41 Wmes Research Center, NASA and 11. Conlnct or Grant No. h*Ames Directorate, USAAMIU)L Ames Research Center, Moffett Field, 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 Air Mobility R&D Laboratory, Moffett Field. Calif. 94035 16. Supplumantary Notes
16. Abstract Several facet8 of large-scale testing of V/STOL aircraft configurations are discussed with particular emphasis on test experience in the Ames 40- by 80-Foot Wind Tunnel. Exariple~of powered-lift teat prngrame are preeented in order to illustrate rradeoffs confronting the planner of V/STOL test program. It is indicated that large-scale V/STOL wind-tunnel testing can sometimes compete with small-scale testing in the effort required (overall test time) and program costa because of the possibility of conducting a number of different tests with a single large-scale model where several small-scale models would be reql~ired. The benefits of both high- or full- scale Reynolda numbers, more deta,tled configuration simulation, and number and typs of onboard measurements increase rapidly with scale. Planning must be more detailed at large scale j.n order to balance the trade-offs between the increased costs, as number nf measurements and model configuration variables increase and the bendfits of larger aTounts of information coming out of one test.
-- 17. Kay Words isu~gestodby Author $1) 18. Dirtrlbution Stutcment
Aircraft Unlimited Design Testing STAR Category - 05 19. Security Uauif, (of thls roportl 20. Security Clorsif. (of this pgel 21. No. of Pages 22. ~ricc* Unclassified Unclassified 15 $3.25
'For solo by tho Nationol Tochnical Informnuon Sorvlco, Springflpld. Vlrginia 221 61 LAROE-SCALE V/STOL TESTING
Dovid C. Koenlg," Thomas N, ALkcn,** rind KiyatihL Avyngi* hmes Rcscnrcli Cnntor, NASA, Mo Efct t Plcld, ClilI farnitr und Michael D, Fnlarekl U.S. Army Aviation Systems Command Air Mobility RbU 1,rtloratory hme~1)irecturatc Ametr Hevenrch Ccntar, Moffett Field, California
hbatrnct FX = axial farce L = lift Scverc' 'ncets of large-scole testing of V/STOL aircraft configurations are discussed with particu- 11 = 11u1nburOF lifting elements lnr ampllusis on exporionco in tlrc Amos 40- by tust PNL = percoivcd noiso lovul, dU 80-Foot Iflr I Tunnel. Exan~plcsof powered-lift test programs u J ~n+esentedin order to illustrntc trsde- l', = irtmosplreric pressure of fs confrot~tingthe planner of V/STOL test programs. P7 = total pressure It is indicated that large-scale V/S'rOL wind-tunnel testing can sometimes compete with smull-scale tost- q = dynamic pressure ing in tho effort required (overall test time) and program costs because of the possibility of conduct- S = wing area ing n lrumber of differont tests with a single large- T, = total thrust (fan ut a = oo)/q(nd2/1) scale modcl where several small-scale models would be required. The benefits of both high- or full- V = airspeed, m/sec (knots) scale Keynolds numbers, more detailed configuration = jet velocity, m/scc (ft/sec) sirnulatior., and number end type of onboard measuru- Vj ments increase rapidly with scale. Planning must a = arlglc of uttack be more detailed at large scale in order to balance fiy = deflector vane setting the trade-offs between the incronsed costs, us numbor of moasurcmolrts and model confj guration vorinbles 6 = flap deflecti.on increase and the benefits of larger amounts of in- formation coming out of one tcst. I. Introduction Nomenclature Development of V/STOL aircraft is becoming more dependent on large-score wind-tunnel test pro- grams than has been tho case for the davalop~nentof AE = nozzle area conventionnl aircraft, Interaction of the pawcr- plant and the airframe introduccts udditional test = AL n (TID,,/~)~,area oE powered lifting pnriuneters, and analytic tools in the process of areo; fully expanded being developed to handle the effect of this inte- nb2/4, momentum area of aircraft gration have not yet been proven, Because of the Am - cornplcxity and costs of some V/STOL models and their AN = nozzle area components as well as costs of flight testing, it is felt that large-scale testing at low speed must AT = cross-"ctional area of wind-tunnel test section become a more significont port of aircruft devel- opment. It is, therefore, tho objective of this b = wing span paper to give the reader soar: insight into the major = width of test section considerations nssociated with large-scale V/STOL bT tcs ting. CD = drog/qS Cd = discharge coefficient The paper is divided into two parts: reasons for testing at large sculc, i.e., scale effects, detail, and acoustics; and test considerations, i.e., C, = pitching moment/qSc planning, sizing, model constructiort, and operu- tions, The presentation makes use of ns many ex- amples as possible from t=st results and from ex- Cv = velocity coefficient periences in testing large-scale powered-lift models. Most of the examples are from programs at = mean aerodynamic chord the Ames 40- by 80-Foot Wind Tunnel and the static = diumeter of lifting element test sites nearby. It is felt, Ilowever, that mony DL of the considerntions discussed are applicable to d = fnn diameter other large-scale testing hcijities where powered models arc involved.
*Research Scientist, Member AIAA. **Research Scientist. lI, _Hya-yon~_f_q~f,L_rpe-SculeTesting Strong sculu affects had bocn notud in past in- v~~tifi~t~utlsof slotted flap configurutlons, hut 'Ihu rcilsorrs for tosting ut luryc sculc ilrc tliesc occurrcd prin~arilyvi tli the power off. llcrc, many, but mucll of the Justifirution can bc plucud wl tli 11 bloutr Fli~p!iys tern, own though instrumenta- sithin the oI)J~~tivosof obt~i~ringclose to full- tion was completu t'or uatli models, ut least toh'ilrd seulc llc!.nolds t\umbcrs, requircmu~~tsfor detni led meeting the objvct ivcs of ttrc resl~cctivotests, rcp~~cscntstionof mode 1 confl guruti ons, and tho tlicrc sti 11 NUS not e~rouglidocun~cntlttlon to slroti possibility of obtaining n Lurge variety of illfor- 1c11y the differelices in lift occurred, TIM prlnci- mat ion from one model, including noise evnluation, pal complications wore probably tlie scnlc cffcct l'u milril~ll:c tho costs and time required for tcst- or1 the rcactton of the jet with tlic flnp systom, Lng botlr large- rind smnll-scalc morlcls, these rca- cornbitled with tlic use of two different power sys- JOnS rnust be clorely cvulurrtcd. 'fb help in cvnl- toms fol- tho two nladels. Those effccts und sirnilnr utrtjan, brief oxurnl~los follow. ones have to bc separated and wcll defined if re- sLIts from smull-sculc powcred ~nodelsure to be Scalc Eft'ecg uscd . In muclr of tlle work that tuns bccn dono in urrtc- Even though with small sizc It is difficult to Igzing scale ofFocts 011 the chuructcristics of lift- provide sufficient lristru~ncntatjon to docun~ent propulsion s!.stelns, there has been di fficul ty In sep- scnle effects, it is continually bcing attcml~tcd. aratlng the combined effccts of ~;~itrgfrom one modcl One program where good correlation bctwaari lurgc and test installiltion to nnotlwr model and test in- nl~dsmall scale was obtoirrcd was in the dc\+elopment stal lntion. For V/STOL uircruft model testing, this of tllc Advanced llarricr and is tllc subjsct of trqa is o continual problem becuuse of tlrc strong effect otl~crpapers in this conf~rencc.~1~TLI a ccrtuin of the simulated propulsion systcm on t1.c acrodyrlamic extent, that case was more straightforward ill that characteristics involved. Exiimplzs of comparisons full-scale results were used as verlficatlon of tllc which indicate such scale offccts are presented in small-scale results in order to quantiFy such Figs. I, 2, and 3 for components of iifting systems things us flap lift lncrcn~cntsand iritcll control, ~hlchare do~umentedin Refs. 1 und 2, and unpub- Purtllcrmi 742, the f lup nnd propulsion systems were lished data, respectively, Even for thesc cor- not complctel!. integrated as was tllc caso for tllc relations thuro are always questions: How ac- exturnnl bloa~~-fiaii(EDF) models uf i:lg. 4, and curate are the surface contours for the inlet tests7 small-scale flap pc~formanccwas not influenced 11)' \$as the grit large enough snd upplicd far enough small dlcfcrenccs in the simulntior~of the engiilc forward on the slut for the case in Fig, 37 But efflux. for testing complote powercd-lift configurations, Jocu~nentingsuch things as similarity in contour, Mode 1 De tai 1- simil~rit!~in flow conditions, or deflections under load can be an order of magnitude more difficult. Vrc comparison in slat effcctivcness shown in Fig, 3 is believed to dcmonstrutc the effect of Problems In correlating tcst results for corn- Ileynolds number; however, there is a chance that plete configurations may be illustrated by the in- slat details such os the mechanicnl reprcsentntion vestigation of an externally blown flop SWL con- of the slat nose and wiper plate thickness may figuration completed by NASA 4 years ago. 3r" Two hove on cffect on slat performance. modcls were built, the larger being six timcs the size of the smaller, with tests being performed in For powered-lift modeis, there have been cases the Ames JO- by 80-Foot Wind Tunnel and the Lairgley of extor~lallyblown flnp tests r~hercbracket thick- V/STOL Tunnet, respectively. The test installu- ness and placement have affected flap position and tions arc shown in Pig. 4. The small modcl was slot gap optimiration. Another exsrnple of the effect powered by ejector propulsion simulators and the of brackets occurred in the development of the NASA large one by JTl5D-I turbofan engines. The small C8A flight test vehicle.7 The aircraft was a C7A model is shown mounted within the liner installcd Buffalo modified to incorporntu direct thrust and a in the 15- by 22-ft test section of the V/STOL thrust augmentor flap. During the development, a tunnel to simulate the 40- by 80-ft test section. 0.7 scale model of the nugrnentor flap was stati- Although the essential purpose was not to look at cally tested, and the results are reported in Ref. Reynolds numbers or size effects as both wind- 8, A section of tho augmentor is shown in Fig, 6. tunnel programs had other specific objectives, the Early in the tests, the upper ?art or shroud wns cffect of scale \
tlarrack, J. P.. Hall, L, P., and kirk, J. V., Variety of Information "Full-kale Investigation of the Law-Speed Aero- dynamic Characteristics of the F-1118 Aircraft," Lnrge-scale models can provide a wider range NASA Ames Working Paper 249, Sept, 1969, in the t)~.ci,mf meirsurcmcnts obtained in one test than sn;~I' ,.I c models. Fleasurements poss ib lc using lurgc ~rcdolsura illustr:~tud ill tlic upper left tl~uttlrc 40- by 80-ft wlnd tunncl wuli uscd for tlrc of Fig. 7 for rl complcto uircr~~f't~or~flgurlttio~. lnrgc-scalu tcstti ut $S70/11rl and n tyl~lcalV/S'FOL hbst of tlrcs~cut1 110 IIIU&!C ilt snlul 1 sc111o, tltlt tllcy tunncl of 5 m Ijy 8 nl, such as ut Lutrgley or Lock- would probably 1.cr1uire scvernl nioduls. Llsia~snal- hucd, wus usvlf for s~null-scaletests at $IFiu/hr. lcr sculu ~nodclu,oltllor cortrpulreiitu or coml~loto 'Ilrcrc vu kuus reprcsurrt di ract costs pl us ovcrhcad , uircraft co~rfigurrrtions, tlio test i tottlr OII tho rlght 'The co~npurisoncan otkly bo quulitattvc since hourly of 1:l R. 7 arc pous r blo , hcous t lc studios rcyui rc rutce c;ltl vury f ron~orru fuci 1l ty to unotlrer', und, special ~nodcl design und testing consldcrat iotrs w11:~rcus wo [Issumo tlrat Irotlr stat LC land wind-tunrrol whi~tr, fnr hoth lirrgc ilnd sn~ullscale, IIIU~require costs urc the sumu, static test rutes i~rclikely scllarotc tos ts . Mcusuring noisc of l urge-sctrlc to bc lowur. 'So further simp1 ify the t.oml)rrrison, n~odels is discussed in llcf. 8, and sj>cclul toclr- cost of ~naturials, powor lila~its, cqull~ment,model rriqucs for ucor~stlcresourclr 111 tulincls nrc troatcd rolmir, pcr diem rlrilt traval cxpcnscs wcrc t~oglcctcd. in Ilof. 11). If ucoustlcs curl be studied In the This docs not invnlidate the com[rurison sitrcu, gerr- same tests, I~orrever, sigtrificnnt cost sl~vings orally, tl~cct~ull~~~~cnt nnd power plants nre alrcndy should IIQ possiblu. uvnilablc +nr irrcorporrltion into tho nrodol and test iautilllutlon, orld tlrc cost of installation refur- For conrl~lctcacoustic moduls, the typical blshm~nt,otc, is less th1111 1Obf totrrl program problems 11t smnll scale contlnue to bc such things COS tS . as sup~~ressloriof noise of ~~ropulsionsimulutors, Ili gh- frequency mcnsurcn~cnts, aird s imulntioti of do- [:or the largo-scale tcsts, tlrcrc was orlo static tail. As scale goes to full size, noise moasurc- and one wind- tunnc l tcs t, 'I'lle smal I-scale l~rogram mcnts in thc 40- by 80-ft wind turlncl must bc mndc wr,s divided illto four sets with the componcnt nlodcls in tlrc ncar Field. RUE. 11 doscribes ail empirLcl11 tested statlcully und the coml~lctcrnodols tested in tochniquc for correcting results for trcar-ficld the wind tunnel. A supmary of the cost co~~~purisorr uffects and compurcs jet rroise rnonsuramcnts witlr is prcsonted ill Pig. I0 which shows tlrrrt total pro- flight tests (Pig. 8). Wind-tunnel and flight gram costs urc approxin~atelytlre same for the two measurements ugrccd witl~it~2 da. With this program progranrs . and othors sr~clras thut of Ref. 12 for cstnblislr- ing the validity of wirrd-tunnel acoustic mcnsura- Ottlcr cuses in which tcst effort was orgarrized munts, six can bo usod to good advantage to it) u $lightly differunt wuy thatr the^ shociti ill simulate botlr detail in tlre lccation of thc sensors Fig, 10 showed tlrut the rnlatlvc costs could vary and the complete aircraft colifiguratior~. This wus as much as 25%, particulnrly when u comj)oncnt test true for the largc SICL model shown in Vig, 4.13 ~t such ns tlrnt for u thrust deflector was nddcd to somewlrat smalltr scale far jet noise studies SUC~I tlrc lurgo-scale tcst program, tiowever, regurdless as that shown ill Pig. 9,1'4 sizc of tlrc installution of this and the ~)rcviously mentioned qua1 i Fications helped to refine the survcy of tlic noise field of hot of the study, it seems evident that the large-scale high-velocity jets at several frecstream velocities. costs do not havc to be much lnorc than thosc Costs required for small-sculc tests if the large-sculc model is designed to combine several dif Percnt Once the need for large-scala tcsts has been types af moasurelnonts during a single series of formulatod, limits on thc use of sucli tcsts havc tests. If this can be progranmod, tlrc large-scale oftcn been placed because of high cost estimates advarltngos of Irigl~Rcytlolds number, Strodla1 number, for the proposcd programs. Tlrc ultcrnutives are detail of gcnlnctry, and meusuremont accuracy can be to use smal?ar models and do more tcsting of air- obtaincd while costing little more thun tlrc cquiv- cruft components. Since, for the latter cnsc, tile nlcnt small-scale testing effort, lnck of largo-scale tcst rcsuIts might jcopi~rdlzc predictions of aircraft Plight cl~aractcristics, 111. Tcst Considerations it was felt that o study of cornparutivc costs of large- and small-scale test progranls was justi ficd. Even thouglr the cos t5 of smnll- itnd large-sc~le Cases were studied which were either completely tcsting ciln be equivalent, a major pr~blemis the largc scalo or complotcly small scule but had com- shortage of largc tcst facilities. Thc wind tunnels mon finul objectives. Orre of these cases is de- capable of accepting some complete nircraft, located scribed below and is bascd on the author's cxper- in the United States, are listed in 'ruble 1. iunce wit11 tcst programs of n large variety of aircraft configurations. The results must trc con- sidered approximutc because of thc following: dif- Tablc 1 Wind- tunnel locations ficulty in-evaluating the impact of compute;- controlled machining and forming on model making; Maxi mum speed, wide variation Ln costs of the smaller wind tun- Facillty, m (ft) in/sec (knots) nels; no distinction in labor rates for different skills; variations in possible conrbinatfons of the 9,1,18.3 xeo) (Langleyl 51 relative effort used irl componcnt and comaloto configuratioii testing, 12,2~24.4(40~80)[Mes) 92[180,rillbc300) 24.4 x 36.6 (30 x 120) (Ames, 51 (100) A comparison was mirde of costs of two tcst design in progress) programs, one at largc scale und orie ot small scnle, . - each producing the sumo variety of information as listcd For tkrc small model in Fig. 7. It was as- sumed that all tho smnll models were still largc Each of these facilities has open static tcst sites enough to justify use nE the tcst data directly to ncarby so that models can be transported bctwccn predict stall aild maximum flap performance; i .c . . facilities without complcte disassembly. The fol- no additional testing time was nssumcd ncccssnry lowing discussion will considc~tests in and near for grit checks and flow studics to detail any the 40- by 80-ft wind tunncl, but much of the dis- local Flow scparatiorr. It was also assumed cussiorr could be up111 ied to planning test programs :ti otlrcr test fucillt~cs. In rucclrt ycurs tlrorc 0) t)t)rrPwi ng or ~C'RS~II~~cqu Ll)nlo11 t u~ldmod01 purts l~.:vu I~OCII two very art ivo open-fiald tust si tus at wllcrc ~>ossthlc . Llu:~surcrnunt~to be mrrdc urc muJ~r I\IIIVSwlriclt liuvc bcorr used For 110tIr tus t l~~gof modul 1) l ~\rririnfiI tulrrs . ]:or V/S'I'OI, witrd- tunnel tvs t lng ut krr 111rcrtlft corrlponcnts 11s well 11s comlrlctc. iii rcruft 1;rrgu sciilc, tho typuu of nlousurernunts arc nlurly UIIJ roll F l gurir t l uns , could illclrrdc ill1 or romo OF fhu fol l~wirigf~i rrtru tost:
1) Stnbi l lty and control ExtrcrLc~rccwith rccullt V/S'IUL test tJrrrgrilnls in the 40- Iry 80- f t wir~d tun~lollii~s rlruwn tli;~tto luducu costs urtd tcetlrrg tlnlc, advtilrccd [)l;i~rtifr~g and nrguni ziktioti cannot hc over ea~~lrusi zed. Scr- vice ur~nnt:utLotrs, contractors, 111rd NASA off iros mirut bc ill1 coordinated and briufcd. 1;iguru 11 5 1 Surfncc prcssuro rncasurcmcn ts on 111 1 sl~owt\the orjii~nl~ution of throc recurrt projects 111 com~loncnts ordcr of i~~trcz,singcost und chtent of or~t1111zution, 'Ilrey rellrescnt oxampleb OF 1) ;In in-lruuse rcscarclr project (Fig. lln), 2) u joint scrvicc-NASA 11.6 U. Aroustlc studios, trcur and far Eiuld progrimr (Pig. 1lb) , und 3) a ~PI'VICC-O~~CII~OLI H) Wak- surveys, downw:ist~, sidewush rlevdlopmcr~t progrum sulrportcd by NASA (17ig. llc). D) lrlow strrvcys ncur tuenal walls to Project 1 test results ore rcportcd in l1uPs. 15 svuluate wall cFfeets nnd lo. This vss un iirtolrrully monngcd, bilsic rusearch projcct wit11 the object ivc of studying stability and control, high angle-of-attuck ctrnr- 111 Structural . >tic ulld dyrlilmic lnndillg actoristics through ~IIBstall, urrd acoustics. Pxoj- oct managcmcnt came from the Ames Large-Sctllc Aero- 12) Aircruft systems clrccks dynamics Branch (UAIl) with both an cnginc and an eirf-amc mnnufilcturer acting as con~ultants. Final A principal problem in progriim mnnugcmcnt is to raporting Wits done by tho LSAH. avoid attcmptii~gso many mcilsirromonta t!iut tho primary gouls ot? the axlicriment arc jeopordizcd Project 2 tcst results uro rcportcd in Rcfs. through complex equipmclrt malfunction, but, at the 17, IS, ~rnd 19. Tl~isrdns a Navy-NAEA jointly Funded same timc, to ttrke Full ildvtlt~tngcof tlrc tcst is- program, mo~~agcdby NASA, with thc objective of stullation, anJ testing time. obtaining static (in and out of gmucd effect) md wind-tuneel Jato for loads, stability nrrd control, Model Sizing and Constructi un and performance. The model was heavily instru- mented to document propulsion and external surface Uurirlg the early dcvcloplnent stage of powercd- Iircssurcs. The test mnagement came from the Antes lift aircraft, components such as deflectors, Aircraft Project Offico, with tho LSAB serving as thrust reversers, OF blown flaps can be studied, iidvisors. 'rlre airframe contructor sulrportcd tho but eventually, the complcto lifting sys tell1 must tests wit11 design, test support, data analysis, be roprcsontcd making tests orr complotc aircraft confi guratione essential. In aitllcr case, consitl- and reporting, eratlon of cost ~neunsresorting to simplifying Project 3 test results are reported in Ref. 6, model construction, adapting rnodcl sizc to oxistirlg This was Navy-fundad with test management coming surplus engincs, or minimizing test configuration jointly from the LSAB, tlre contractor, and the clionges . Navy. The rnodel was equipped primarily for full- scale stability, control, and performance checks Sizing with the instrumentation required to documcnt power settings together with u few loads. The cost of For model scales which makc full t~seof the 40- ex- tho model was un ordcr of rnag~ritudehigher than the capacity of tlre by 80-ft wind tunnel, our perience has been that size is dictntcd by avail- foregoing projccrr be cause the model combinud n fuselage Plight structure with the Rolls Royce able energy sources sucll as compressed air capacity and electrical motor and gas turbino avail- F402-R-402 engine and a boiler plate wing-flap sizes system. In addition, since the tests wore part able. As will bo discussed, the size of gus tur- of on aircraft development program on n tight bine engines which hove been developed for business schedule, it was highly "visible," and a largc jet aircraft odapts well to model scales of 0.3 to number of controctor personnel were requir~dto 0.7. For larger models, tlrere is n jump in thrust to the 10,000 class which will force the norody- support the operation of the tests and correlate Ilmits tcst results on a daily basis. nnmic size and result in large wall inter- ference effects. The estimation of these effects Ilb and llc then becomes vital. Reference 20 relates aircraft The test programs of both Figs. si proved not only to include and require extensive aird wind-tunnel geometry to model-tunnel zing parameters in order to establish tentative sizing coordination between groups, but they were a153 criteria for V/STOL wind-tunnel testing. Correla- This was true in spitc of their use of expensive. tion plots from that reference ore presented in scmf dl the fol Lowing considerations. tliglr costs Fig. 12 and hnve been updated with the modcls of can iometimos be cut by the following: 1) use of h, The boiler. plate construction for modcls, 2) cnrcfr11 Refs. 15, and 19. lines have been somel~hat evaluation of trade-offs in complexity and cost, arbitrarily drawn in the figure to represent guide- lines of good wind-tunriel flight corro1ation. The 3) use of increased tolerances where at all pos- sible, 4) use of analytic methods and algorithms r~alleffccts for the largc configurations and for in planning the test procedure, 5) coordinntior~wit11 decelcrotilrg fligl~tcan be significant as shown in small-scslo programs to minimize duplication, an3 Rcfs. ?t nnd 22, and the ranges of Fig. 12 might well be lowered for thesc cases. tlowcver, it is in Vig. 17. Sincc ilro lardel wus to bc uscd to invcutigntu rrlrcrt~ft.s',.uhlllty, control, n~tdstull chilractcrist i e?i , I t wus docidud tltst tho wui girt of the itt~culle c0~11dbe ~ulljrortod fro111below wi tlr nn Currorltly, the ,nost jrcuct l cul of tlrc ulrcrj:y ovors I rut1 111111 9t r l'f pylon II~I~III. Il~ithort111iti LIS~ sources uvullublc for 410- by 80-ft wind-tur~nul modal ux[~enr;l vo slrol 1 r~iount to tn; r~imizo ovcrsl 1 usc is tlie smull turbojet or turbofa11 cngil~v. 'Iko nnccl le r~idtlr, the o~rgirioawurc movad nutltuutd or) ortgir~ev uvni lablo arc sliowri iri Fig. 13 togcthcr tlic wl~r~to mu~ntain u rctluirod 1otrgt.h of cxllosod with tlrc opcmting p:!Imunlotcr.s for maxlmram corrt in- wing lcadln~edge betwean thc ~rucollcsutrd t11c \lous pei~Porrnn~~ce.Amu~ nttcmpts to maintain 11 suf- f~tsclllgc, Irr tcrnls of percunt spun, this wus Less ficient rlumbor of ouclr to poncr modcl col~ffpurutionr ttbun 1% s1)nrr Ftirtlt~rout 011 tlre wing. For tlris lluving t'rom four to slx onglnos. Tlrcsc angi!res, cusu , thc moximurn rrozz lc pressure rr~tiorm.! optln~um plus otlrcr gos porter sources, hsvc been plncud or1 duct pcrformuncu wore not nocdod, so tlra ir~tcrnrrl the thrust-pl.ussuru ratio mup of I:ig, 14. llte 'r58 ~rozzlccorrtours wcrc not criticill us long rrs the und ,185 uro uscd to drivc tl~cLP576 arrd Ll:336 tip- surfr~ccswccc ~:o~~tirruousund smootll irr a scroilmwiso drive11 funs, rcspectivcly [0,91 m I3 Ft) diumutcrj. direction. To cnsc tlris situutiort, tho nozzle was Tlro LF376 funs rrrcrc used in tlrc nrodcl slronlr in Fig. mnde o+vcrly long to reduce curvuturc. 'I'hi s rnndo 15 (the model uscd in :hc progrunl of PLg, llb) . it possll>ls to uuo scgn~cntcd,rvuldrjd construction Ilro d115 hus also been used ns a lift originc orIeritcd of both the hot nrid cold nozzle ducts with oxtarnnl in a vorticul thrusting positlon for thc program formcrs ds showl~. 'Rro forwurd skin wus rollod of itof, ?3. 11) ndditlon, this c~rgincIrns driven shcet stool with ucccss pnncls pluccd to casu tlra turbines of modified Viper errginus for uhicll surviclng nrtd engine chocks (no compo:urd curvas) , the compressor output is used to power blourr flap Ilic skin on ttru nozrlc hud to lruvo a corqow~d modcls such as that reported in Rcf . 22 or for corvuturc, but it was covcring tho c?iltcr duct and the blown semispan installutio~isllown irr Pig, 16. could bc fiberglass, '[?re inlet uus spun-fornled for prevj ous test progrums ur~dwus rcndi ly udolrtud to Additio~lalsources of energy suctr iis higlr- tlie tracalle frunlework ttnd cowling. hftcr the first pressure air and electric powor hnvc bccn consid- tcs t , the lowcr lluccl lc contour wilr ri~odificdoco- ered only as auxiIinry power for lurgo-scnlc models, nomicrilly by adding fonm nnd fibergluss for all four except for tfre electric motors driving rotary- nncellcs. Ilr is irlvolrod ~ppfo~lrmiltcly100 man- wing or props1 lor-driven madoli; , As tho higli- liours. prossure uir sourco cupucity is increased at tlre wind tunnel, it could be prncticol energy sortrco 'l't~e sccolrd exnnaplc is tlrut of thc complete for medium-sized stntic or dynamically slmilur VTOL. rrretllod used for the program of Fig. 11I1. Ilie models, 12-in, -diamntcr tip-driven fun inst;illu- nrodel is shown in Pi[;. I8 (during its cot~struct~on} tians, and boundttry-layer control ;3LC) systotl~sfor rind i:i Fig. 15 (fully complctod!. Thruc T58'5 large-scale mnodcls. Target cajlacity for tlic nir r~oadcd to powcr the LF336 fur& wcrc Irouscd in the supply is 32 kg/scc (70 Ib/sec) at 2000 psi milximum fuselage und ingcstud air fronr thc two sidr inlets with a continuous rating of 11 kg/sec (25 lb/sec). (one is sliswn installed). Ilic hot ducting was we1 1 For information on available electric motors and insulated and bay cooling wtls an cssontiol part of maximum load, the reador slrould consult Rcf. 21, tlic design, making it possible to form most of tlic conipound surfaccs From Fiberglass, pnrticulurl y Tho foregoing has beet) a very brief discussiotr the si~nulfitcdcirnopi and .' c inlets. Most of tlru of the practicnl constraint on sizirrg large-sculc surFaccs wero defined by ~!8-to l/l-in, steel riha models, tho porvor plant, A major need is for a or btrlkttcads, ])recut to n computed curvuturc for small or medium-siztld, trigh-hypilss-ratio turbohn that purticular cross scction and welded in place or n prnctical sctierne to ;imulltte it, It is hoped to a base frumtrwork. In hot uroas, stritrgcrs were that further develupmcnt of the business jet will instulled, nrrd steel skin wus plug-wcldcd or bring about such an englnc, The closest to this screwed to these formers which bccame atr ititcgral is the LP376. Dctcrmining tho nvnilrrbllity of $art of tho structuro. In cool areas, foul11 rind these and other possibilities, such ns the cngincs fibcrgl~~sswore instnllcd botwccn tllc forrmru. 336 listed in Figs. 13 nnd 14, as well as electrical wing and Flaps had a steal spar and were covorcd nnd high-prossure ui-r sources, becomes an esserl- with rrood urrd u single luycr of flbcrglnss. S.11al1- tin1 considcrntian in tho plnnning of a prolrosed tolerance nrcus were Ireld to the outer wing, flaps, powured-lift program. and inlots. Construction setup time was consid- erably reduced by increasing tolcranccs in other Construction arcns whore possible.
Exporicncc in constructior~of large-sci~lc mod- A very significant note mtrst be made about els has shown that, for most cuses, so-called locilting instrumentation on modcls such as that just boiler plate construction is ndcquutc and no more doscribcd. Tltc scnnivalvcs arid rnisccl Jancous trans- oxpens ive for P given aircraft configuration than dur9rs which arc located crl the model must be ac- for $ma1 lcr .nodal5 requiring rnaclrining, advanced ccssiblo and compatible with cooling requirements, casting techniques, und many mnn-hours of finish- For the uhove model, it was difficult to find a ing. fiowever, to profit from the advantages of coo! arca in which to install tlicsc units (an area "boiler plnti~~g,"expansive forming, casting or cor~trallylocated to minimize pressurc tubing machining arc not utilized, u~llcssthcsc methods length]. The finill position was bctwccn the outer are iibsolutely required to ~ccuratclysimulate wing rind tho giis generator inlet duct. The prob- perforn~ance i terns such as inlet, slots, or wing Icm was recently made siglrificant when on onbo~rd leading-edge contours. To illustrate trade-offs. data acquisition system was mndu optional for 40- oxamplee follow. by 80- ft willd-tunnel modcis, This systcm requires locating Kemotc Multiplexing Distribution Units 'the housing for thc JTlSD used on the uppcr (HMDUts) on or near the modcl, preferably near the s~lrfaceblown-fli~p (1ISU) modcl of Ref, 15 is sllown scnnivnlves. Alttnugh use of tlic RHDU15 will not t~cruc~rr I red, they nil 1 yruatly rodrrcu Iiookul) tblid tunnul s[r?cd L s ud)bi~teJrn.11rl1111 ly, this rc(iul I'US lrrosrurc chock t imo. good coordltrir t i dl) botwuon the wl nd- tun,~ultind cnglnu ulrurtitorn [ur modcl controllur), Irinos ra~~roscljtin~ltru wind-tunncl rhrrructcristics with ttic modcl out iI1.U 11150 SIIOW~I fop TO~C~OIICC. '191~ 'he limited uvailut~lityof large-sculc wlrrd vrrl uuu of At1 hero clrosuri to brucket tlru ot(:rl\*ulcrlt tunlluls mokos It imlrorutivc tlrut tlrc conljrl~tctest wind- tunnel ~loli t- chunye roquircd to compcrrsutcl ~WOccdurccvolvc? from trudu-oft's kn tlllurcl tilllu for thu tlrrus t rlrurrgo III tho tast soctiua. '111~ ib~rrl 11iodc1 com~)l~xltySLIC~I US tlru ~rulntrar of onbourd probloms with wind-tunrrel s 1ru uru illustru tcd by mcnsurcmc;its or tlie ~rumbcrof conf i gurnt Ion vilr- tho lirrgc uir ctrcultrtion tlmo OF 8U scc for 60 i if.bloa. For jlowered- 1l ft I)TOpfbmS, tt\c uXI)CIISU of hrlots, a cormnonly usod tcst ulrspu~dfor \I' OL the modcl and justificutlon for stitrti 11g thu pro- tra~rsltion. In prncticc, in ardor to bo rrvsrlrcd gram in tho first plr~ccsoom to bring prcssorc from chat uirrpocd has stoppod varying, tlru tlmo takcn a1 1 part lcipants to I~lcrouuu ttru nwlllror of Illuosurc- 1s ubout twic~thirt indicated for the 50- to 60- murrtri a~rdtcs t virriubles . 'Ihe fa1 lowing conrmcrlts knot rnngo, about 2 mill, the lust mlnutc is ~~WII- uru designud to help with judging tlia inapact of crully consuared by fino ndjustruuats to oirspood. increasing con~ploxity 011 wi~id-tunnel t ime . A computer-controlled spccd radjustmont trow buln~ considerod fur tlw new 40- by 80-Pt/BO- by 120-ft FLgurd 19 shows tho rutio of totul down timu tost powor systen~may ulimirrutc the need for this to on-site time as u functlon of tho number of luttcr pcriod of udjustrnont, tlowcvor, in spite of modcl d:onfigurutio~r vuriublos, 'Ihc vcrtical sculc inl'uts from inodul powcr co~iditions,ungt.~ of rrttuck, is sllding since tire actual rutio cun depond on or uir temjloraturu, sucl~a spoud coritro. systom too marly fuctors beyond our con tl'ol. A good tiumber will stjll Illtvo dl fficul ty ~IIruducing the timc for zero chongus with power off is 30 us u sturt. indicated irt tho t'igurt* simply becuusr of tliu largo ?ha estimutions or frlircd curves are busud an 350 volu~~~cof uir circuluting in tlra tuHlrc1, onbonrd moosuremonts. 'I'hc tost cuscs hove upproxi- mntcly this number of mousuromcnts. Some of tire A miijor prol,lcm in opernting with gns turbine results come from tlro uuthorls experiences and ore enginus results from tlro lack of o positivc vctb- quulitativo, but thu curves arc primarily derived tiluting system and u pra~ticuloperating limit of Erom tho USD terts,15 lift-cruise fan nrodcl tosts,lg 130°t: ilr the tcst scction. ,\s shown in Fir:. 22, ltnd augmentor wing t~stu,~~'I'hc effect of jroiror is the use of gas tur1)ins engl~le; ~'osultsirr e curttiin showr. on the plot at zero configuration chungos maximum running time. After this, the engines must and should ha typical of thc penalty paid for en- be shut off, the uppropriutc doors opened, und tho gino maintenunce, timc required to purge tho tun- tunnel run nt lor+ speed for purginp or for reducing nel of exhlrust gnscs, and cooling of tho air in the uir temperature. Currently, this takes 20 min to tunnel. Thc steeper slope with tllo First two con- 1 hr. To ruduce this time, which is essontlally figuration changes reflects the assumption thut lost for test purposes, un attempt is uvuolly made these two arc major chnnges (such as tail instul- to scl~edulcV/STOL tosting with engines in the cool lntion or removal silbicll can take 2 to 4 hts in tllc months and/or restricting operntion to evening und 40- by 80-ft wind tunnel), early morning hours. Note that tho choice of power plnnt and sizing of the model have a strong in- 1:igurc 20 shows the vnriotion in timc required fluonco on this time. Tlre problem will certainly to record each dntn point tis a fullction of the num- be eliminated in operating tho 80- by 120-Ft test bor of onboard monsuromcnts. No accounting is section, made of power changes which at times must bo made to kcop up with chongcs in tunnel air temperature In summary, tho major factors to consider in and wlrich can oJd en udditional 30 sec to some attempting to minimize wind-tutrncl time for large- data paints. These ninor throttle adjustments con scale V/SWL modcis are, to n ccrtni.n cxtent, usually be done during changes in other settings similar to thove of other powered modols. In both such os angle of attack or sideslip. It has been cases, power nnd instrumentation culibrations should assumed thut the first 1-1/2 min consist of: be done prior to model testing, model parts should setting tho test conditions such RS angle of uttnck, bo flttcd, and run procodurus planned in detail. sideslip, or powor; letting the tunnel airspeed The mujor differences appear in operations where, -toady out; and recording the data Ercm tho scale for tho larger tunnels, settling times urc largo; *tern. After n 12- to 15-soc scanning period, for closed-return tunnels, gos generator operation lrding with the model data system is started. brings thc need for purging time. Another Foctor bough, ns the systom itself is refined in the which has not boon mentioned is that tho logistics .ure, tltc slope of the curve could decrease of making model churigcs in the larger wind tunnels .ightly, the penalty in tosting time becnuso of urc completely different since the model is 15 to anboord meusurcmonts is significnnt enough to war- 40 ft above the wind-tunnel floor. To take advan- rant inclusion in the initial planning of the pro- tage of thc larger size in order to gat many types grum. In arriving at the I-1/2-min period shown of data, this difFerence must Ire rccognizcd, und in Fig. 20, it was assumed thiit any thrust changes accessibility problems must bc anticipated at the would be only chose required to compensate for inception of the prograh. tompcruturc changes, and tunnel powcr would hnve to IV. Concluding Remarks bc changed in small increments bctwccn data points. 1,nrge-scale V/STOL wind-tunnrl testing results Figure 21 illustrntes the problems encountered in benefits of both high Reynolds numbers and more in estimating tho settling timc required after u detailed configuration simulation, and tho number rapid thrust or drag change is made in the tcst und tjpe of possible onbonrd measurements increaso section. The cross-hatched area represents an as- rapidly with scale. Large-scale testing con some- timate of the minimum required timc, assuming thut times compete with small-scnlc testing in terns of wind-tunccl drive power is changed to compensate tho effort required (overall test time) and program the thrust change at tho same time. Since the costs bccnuse of the possibility of conducting a number of different tests that would require 11Jdltiu11ul $rrrall-sc~ilcmoduls. Plutrrritrg rnllst be I~l:nlare~I,El. I), , Aikun, '1'. N,, Anyugi, K., more dctuilud at ltrrgo :o%clu itr order to t\i~luncc und Koonig, I). (i. , "Cunllrurison of Acoust LC! Cfrnr- t llu trndc-of fs botwoorr tkc ilrcrutrsud costa, as IIUIII- acturlvtlcv of' Lurgc-Scalc Lludulv of Suvor111 Pro- bur uf inuuuilr.cmolrts unti sotlul cot~flpurutlor~vur- puls i vu- l,i ft Currccllts ,'* Jorrr~~ul,of iiJrcruftS*, tclrlcu ~IIC~C'IISU,JII$ thc $onof i ts of lurgor urnouats Vol. 12, July 1!175, pp. b00-(10cl. of Lnformutloa comi~tgout of orru tust. To tlolp 111 uvalutrting tlruvo trsdo-offs, tlcvuri~l ftrcots OF llb,laock, C. J, , 1t5tstic und Wlnd 'hmncl Noar- lorgo-su~lo tusting hiivu buon ~~roscl~ccdwltl~ purtic- Iricld/l:ar-iliold Jot Naiso Fluuvurcmcnts franl Modul ular unllrlruuis on tost cxpuricnco In thu Anion 40- by Scula Singlc-Vtnw Ilusclino und Suppruasor Nozzlus ,'* Hfl-ft Wlnd Tunncl . Val, :: ~ai;u,$ouxoLocations and U~tr111)ol~ of of titic Frcc:I!?ld Jot Noisu Until, xu~a(X- 157913, Scpt. 1376. ,101, IT; =jlrd S1)ccd liffllcts, NASA CR- 137913, NoV. 197h. lblort, K. W. , llSu~~~rnuryof tirrgc-Sc111a 'I'cs ts of DuctuJ I;urrs," Paper 8, Co~ifcrunccon V/STOL nt~d 151\oyagi, K, , Fularski , M. D., und Kor*t~lg, U. a'l~l,Alrcruft, hcs ncscurclr Cc~~tcr,hloffutt Pield, G. , I1Wilrd 'Turrncl lnvcs tigut ion of a L~lrgo-Sctllu Ci11 J r, , lt)6(1, NASA SP-116. U111>er $ur..~cc Blown-Flap 'I'rnnsport hloJo1 tlnving 'Two Engines," NASA Tbi X-02,296, Aug. 1973. "liickuy, U, 11. , l*V/SWL Aerodyaumicu: A lte- vicw of tlru ?'cct~~rology,~~ACAAD Co~lfcrunccPrococd- I6~ocnig,11. G, und Aoyogl I K,, wMuximunr Lift of Lngs 143, I1nl~cr1, Dclft, tho Nctherluods, 1073. tlppcr Surface Blowing STOb Aircraft with Swept IYings, t1 AIM Pu1)cr 75-868, Ilortford, Cenn., 1975. 3~0yagi,K., I:ulurski, bt, D., und Koonig,)1. G., ilWt~~d-'f'u~rncl111vcutiyatLon of n I,nrga-Scala 25 17~nmbusci,B. J., Aoyugi, K., und I{olls, L. S., Swept-Vliag Jct Tru~ivportModcl w tll en External "Wind Tunnel Investigation of a Lurgc-ScaIe Modcl Blowing 't'riplc-Slottcd ?lap," NASA, Tbl X-62,197, of a I,ift/Cruisc Fan V/SlDI, Alrcrnft," NASA TM Nov, 1973, X-73,139, May 1976.
4Guntry, C. L., Jr., tlWind-Tun~~olInvos?ign- la~umbucci,U, J., Aoyugi, K., anit RoIls, L. S., '.Lon of an Intornally Blor+~tFlnp STUL transport ItWiud Tunnol Invustigution of u Lur~e-ScalcModel Modcl Including UJI Invcstigntion of Will1 of u Lift/Cruiua Fun V/6M1. Alrcruft with Extendod NASA 'FM X- 3009, Sept . 1'374. Lift/Cruise Nucella~,*I NASA 'l?4 X-73,lfi4, hug. 1976. 5~iillor,K. und Luccy, T. R. , tlThc AV-8D lying: gll~indTunnol drld Ground Static 11~vc~tLgation Acrodynomic Concept and Uusignl8' AIM Paper 77-607, of u Largo Scale bfodcl of n Lift/Cruisc Fan V/SI'OL Moffctt Field, Calif,. 1977. Aircriift," NASA CB-157916, Oct . 1876. Gtlollingsworth, E. G., Aikcn, T. N,, and Huggct, 2°#ickey, D. li, and Cook, W. L., liCorrclation J., llVnlidati~nof AVB-U V/STOL Charecterietics of of Wind Tunnel und Flight-Test Aerodynamic Data for 1:ull-Scnle Static and Wind-Tunnol 'restsIt*AIAA Fivc V/STOL Aircraft," prcsvnted nt the Plight Pnpor 77-597, Moffctt Picld, Calif ., 1917. Mochunics Panel Mooring of AGAIlO, Romo, Italy, Oct. 1965. 7~uigley,tI. C, and Vomaskc, R. F., "Prelim- inary Results of Flight 'rests of the Augmentor- z1l(ouniL, D. G. md Corsiglia, V, I!. , 'lAcro- Wing Jet SlUL Hoscurcli Alrcruft," S1'0L Tushnology dynamic Chnractcristica of a Large Scala Flodol with Conferonce, Paper 20, he:; Research Centor, Moffett an U~\snoptWing nnd Augmontcd Jet Flop," NASA TN l:ield, Calif., 1972. D-3610, June 19CU. a~orkonan,L), L., Wi~~tormoycr,G. I:. , und 22flcyson, H. It., ',Rapid Estimation of Wind Wright, F. L., "Stotic Tosts of il 0.7 Scale Aug- Tunrhel Corrections with Applicntion to Wind Tunnel mentor Wing Flap for tEl~a Modified C-8A Airplane and Modol U~sign,~'NASA TN R-6416, Scpt. 1971. 'Test Results ond Anilly~is,*~NASA CR-114315, 1971. 23~olhurst,II. H, and Kelly, M. h,, "Character- g~alarski,M. D. , Koenig, U. G. , und Sodcnnn, istics of TWOLargtt-Scnlo Jet-Lift Propulsion I*. T, , *lAspccts oE Investigating SML Noise Using Systems," Conference on V/S'ML and SML Aircmft, Large Scille Wind Tunnel biodol~,~~Canadian Aero- Ames Rcscurctr Center, bloffett field, Calif., 1966, nautics and Spnce Journal, Vol. 19, Feb. 1973, NASA SF-116. pp. 61-69, zh*+~uidcfor Planning Invcstigntions in tho Ames lo~odermatr,P. T, , "Instrumcnt~tion und Tccll- 40- by 80-1:oot Wind Tunnel," Arne5 Resonrcll Center, niqucs Eor Acoustic Research in Wind Tunn~ls,~~6th MoFfott Field, Calif., June 1975. ~rrternutiorlalCongross on Instrumcntution in Acro- space Simulation I:acilitics, IELE Pub.,ication 75 ClHl 993 6 hES, 1975.
listrout, F. C. and Atencio, A., "Flight Effects on JT8U Engino Jet Noisc as Measured in tho NASA Ams 40- by 60-Foot Wind Tunnel," AIM Pnpcr 76-556, Palo Alto. Calif., 1975.
12~tcncio,A. Jr,, "The Effect of Faword Speed on JR5 Engine Noisc from Suppressor Noeztcs us Measured in thc NASA-Amcs 40- by 80-Foot Xind Tun- nel," NASA TN D-8426, Feb. lCJ77.
WING MOMENTUM AREA AATlO
"\$\\ 0 XV3 0 VZ3 0 .XC 142 A A XV4A h h XV6A b h AVBB - 0 Lld 3 ,002 - 3 + uss4 ,001 DISK NEVJTONIMETEFI~ I.O#TYING
-111111111*-1 I' 2 10 loo imo in000 lb/ft2
ul I - ' t rrr~d molnunturi urnu .; izin$:.
b XV 6A b AV 86 0 L/C 3 0 USB 4
DISK LOADING
b) Wing span sizing.
Pig. 12. Sizing pnramctcrs. THRUST W P~/Po A"
N (~b) kolsoc (Ihtooc) rn2 in?
*' I-;- 'Zi2--Jj+ * j* k:dlk.p-.,%%p-,I..., I..,..,.,., ....I., ,...*.... .i '+-+ - 0 -. - *&
Fig, 13 Small turbofan or turbojet engines nvclilnblc for use in largo-scale V/STOL testing.
REFERENCE LINES
WHERE:
It) ESTIMATED
Fig. 14 Summary of possible gas energy sources (continuous running limits unless otherwis.: noted).