NASA Quiet Haul Aircraft

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NASA Technical Memorandum78545 t

[NASA-TM-78545) AN OVERVIEW OF THE QUIET W79- 11034SHORT-HAUL RESEARCH AIRCRAFT PBOGBAI ( N A S A )41 p HC A03/flIF A01CSCL 01c Unclase3105 37159

An Overviewof the Quiet Short-HaulResearch Aircraft ProgramMichael D. Shovlin and John A. Cochrane

November 1978

National Aeronautics andSpace Administration


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AN OVERVI EW OF THE QUI ET SHORT- HAULRESEARCH AI RCRAFT PROGRAM

M chael D Shovl i n and J ohn A. Cochr aneAmes Resear ch Cent erI NTRODUCTI ON

The Qui et Shor t - Haul Resear ch Ai r cr af t (QSRA) i s a new r esear ch ai r cr af tBecause the nature and use of r esear ch ai r cr af t bywhi ch NASA wi l l use as a f l i ght f aci l i t y f or advanced f l i ght exper i ment s i nt er m nal ar ea oper at i ons.NASA are f r equent l y m sunder st ood, t he f ol l ow ng di scussi on i s pr esent ed tocl ar i f y t he subsequent descr i pt i on of t he QSRA and i t s use as a resear ch

f a c i l i t y .NASA r esearch ai r cr af t ar e not pr ot ot ypes and f r equent l y they ar e notexper i ment al ai r cr af t . For exampl e, t he Kui per Ai r bor ne Obser vat ory, whi chi s operated by Ames Resear ch Cent er , i s a st andard Lockheed/ USAF C- 141 modi -f i ed to car r y a t el escope and ot her ai r bor ne sci ent i f i c exper i ment s. Ot herr esear ch ai r cr af t such as t he X- 15 seri es ar e hi ghl y exper i ment al i n nat ur e,but ar e not pr ot ot ypes f or f ut ur e ai r craf t . Occasi onal l y, an ai r craf t bui l tas a pr ototype i s used as a r esearch ai r cr af t ; exampl es ar e t he Boei ng DashEi ght y, whi ch was t he707pr ot ot ype and t he USAF AMST pr ot ot ypes.cr af t wer e used or pl anned t o be used by NASA f or f l i ght r esearch af t er compl et i ng t hei r pr ot ot ype m ssi ons. Al l of t hese ai r cr af t had a commondenom nat or : as r esear ch ai r craf t t hei r m ssi on was one of dat a gat her i ng,and i ndeed, t hi s i s usual l y t he pr i mar y m ssi on of NASA r esear ch ai r craf t .For t hi s r eason, NASA f r equent l y vi ews r esear ch ai r craf t as f aci l i t i es, j ustas a w nd t unnel or a si mul at or i s consi der ed a t est f aci l i t y.

These ai r -

The dat a resul t i ng f r om t he QSRA f l i ght r esear ch pr ogr am wi l l be used byt he Uni t ed St at es ai r cr af t i ndust r y t o est abl i sh desi gn cr i t er i a and by r egu-l at or y agenci es t o est abl i sh cer t i f i cat i on cri t er i a f or advanced STOL ai r -craf t . Thi s i s i mpor t ant f r om a nat i onal poi nt of vi ew si nce ai r craf t expor t sexer t an i mpor t ant posi t i ve i nf l uence on t he U. S. bal ance of payment s. I naddi t i on, QSRA f l i ght dat a wi l l l ead t o i mpr oved ai r t r anspor t at i on at r educednoi se l evel s and wi t h l ess ai r t r af f i c congest i on.Anot her char act er i st i cs of many NASA r esearch ai r cr af t i s l ower cost t hant hat t ypi cal l y associ ated wi t h a pr otot ype devel opment . Li m t ed budgets andf i scal r esponsi bi l i t y di ct at e that r esear ch capabi l i t y must be maxi m zed rel a-t i ve t o cost , and exper i ence wi t h r esear ch ai r pl ane pr oj ect s has l ed t o cer -t ai n approaches devel oped to m ni m ze t hei r cost. These i ncl ude:

1.2. Use of of f - t he- shel f hardware3 . Use of goal s i nst ead of r equi r ement sUse of an exi st i ng ai r f r ame where possi bl e

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4.5.6.7.The

The

I n- house par t i ci pat i on wher e appr opr i at eCost consci ousness at al l or gani zat i onal l evel sSof t t ool i ngI nf or mal document sappl i cat i on of t hese concept s t o t he QSRA wi l l be di scussed l at er .

HI STORI CAL BACKGROUNDNASA has conduct ed r esearch wi t h power ed- l i f t ai r pl anes si nce t he 1950s.f i r st j et STOL r esear ch ai r pl ane devel oped by NASA was t he Augment ed J etFl ap STOL Research Ai r pl ane ( ref . 1) devel oped i n t he ear l y 1970s. Thi s wasan aust er e pr ogr am whi ch consi st ed of a modi f i cat i on of an exi st i ngdeHavi l l and C- 8A Buf f al o, powered by t wo modi f i ed Rol l s Royce Spey engi nes.I t r ecent l y compl et ed 500 hr of hi ghl y successf ul f l i ght r esear ch and af t era maj or i nspect i on has been pl aced back i n ser vi ce f or f ut her wor k. I t s

per f or mance i s r epr esent at i ve of t he f i r st gener at i on of j et STOL ai r craf twi t h an appr oach l i f t coef f i ci ent i n t he 3. 5 to 4.0 range. I t s maj or l i m t a-t i on i s hi gh l evel s of si del i ne noi se.A second, mor e ambi t i ous j et STOL r esear ch ai r pl ane pr ogr am i ni t i at edi n t he ear l y 1970s was t he Qui et Exper i ment al STOL ai r pl ane (QUESTOL). Thr eepr el i m nary desi gn st udi es and a desi gn compet i t i on (won by Lockheed- Geor gi a)wer e compl eted bef or e thi s proj ect was cancel l ed i n J anuar y 1973 due tobudgetary l i m t at i ons. The QUESTOL was pl anned as a f our - engi ne, exter nal l ybl own- f l ap STOL ai r pl ane, power ed by f our Gener al El ectr i c TF- 34 t ur bof anengi nes.I n J anuar y 1974, a deci si on was made t o embark on an aust ere j et STOLr esear ch ai r cr af t whi ch woul d f eat ur e ver y l ow si del i ne noi se l evel s and nextgenerat i on' ' per f or mance ( appr oach l i f t coef f i ci ent of 4. 5 t o 5.5). Prel i m n-ary desi gn cont r act s wer e awar ded t he Boei ng Commer ci al Ai r pl ane Company andt he Lockheed- Geor gi a Company t o st udy an augment ed j et - f l ap concept and ahybr i d upper sur f ace bl ow ng concept . These st udi es wer e not compet i t i ve i nt he sense t hat t hey di d not f or m t he basi s f or t he sel ect i on f or t he w nnerof t he subsequent har dwar e compet i t i on. Each desi gn t eam operat ed i ndepen-dent l y, and onl y at an i ndust r y- w de conf erence at t he end of t he st udy wast he wor k of one team r eveal ed t o t he ot her . I n t hi s way, NASA was abl e t oobt ai n t wo i ndependent appr oaches to t he pr obl em The r esul t s of t hesest udi es wer e pr esent ed t o i ndust r y i n Sept ember 1974 ( ref s. 2, 3 , and ar equest f or pr oposal f or det ai l desi gn, f abr i cat i on, and test of t he QSRA was

i ssued i n November 1974. I mpor t ant excer pt s f r om t he i ni t i al st at ement ofwork ar e gi ven i n t abl e 1. Boei ng, Dougl as, and Lockheed responded t o t her equest f or pr oposal and af t er a l engt hy eval uat i on, t he Boei ng Commer ci alAi r pl ane Company was awar ded the hardwar e cont r act i n Mar ch 1976;The QSRA made i t s f i r s t f l i ght on schedul e- J ul y 6, 1978. The ai rcraftdepar t ed Boei ng Fi el d i n Seat t l e to go to Pai ne Fi el d i n Ever et t , Washi ngt oni n or der t o begi n i t s i ni t i al 17. 5- hr f l i ght - t est programpr i mar y obj ect i ve of t hi s pr ogr am was t o demonst r ate the ai r wort hi ness of t heAl t hough t he

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ai r cr af t and i t s syst ems, t he l ast 2 t o 2. 5 hr wer e devot ed to i nt er nal andext er nal noi se measur ement s. Thi s i ni t i al f l i ght tes t pr ogr am pr oceeded verysmoothl y and was accompl i shed 1 mont h ahead of schedul e, al l ow ng t he ai rcraf tt o be del i ver ed i n August i nst ead of i n Sept ember of 1978 as ori gi nal l ypl anned. Fi gur e 1 shows t he ai r craf t on f i nal appr oach i nt o Mof f et t Fi el d,Cal i f or ni a where 9. 5 hr wer e f l own i n or der t o ver i f y dat a system oper at i onat Ames and to pr ovi de pi l ot f am l i ar i zat i on and tr ai ni ng.i nspect i on of t he ai r craf t and i t s engi nes, t he second phase of t he NASAf l i ght r esear ch pr ogr am was begun i n November at Ames wher e t he pr opul si ve-l i f t , handl i ng, and acoust i c char acter i st i cs ar e bei ng i nvest i gat ed, w t hi m xovement modi f i cat i ons as r equi r ed.

Af t er a t hor ough

MANAGEMENT APPROACHThe t ot al f undi ng f or t he QSRA was est abl i shed at 29 m l l i on i n J anuary

Si nce t hese f unds had t o cover cost s1 9 7 4 . At t he st art of t he proj ect , a f i r m comm t ment was made t o compl etet he pr oj ect w t hi n t he avai l abl e f unds.f or al l st udi es, t est , engi ne and ai r f r ame pr ocur ement , and pr oof - of - conceptf l i ght t est s, an aust ere and i nnovat i ve management appr oach was r equi r ed.The appr oxi mat e di st r i but i on of t he avai l abl e money i s gi ven i n t abl e 2.

Scope Versus CostThe techni ques di scussed i n t he I nt r oduct i on were al l appl i ed t o the taskof devel opi ng a t echni cal l y meani ngf ul pr oj ect wi t hi n t he budget ar y l i m t a-ti ons. An i mpor t ant aspect of l i vi ng w t hi n t he budget was def i ni t i on of t hescope of t he pr oj ect , whi ch was l ar gel y accompl i shed dur i ng t he pr el i m nar ydesi gn studi es.want i t to cost. Thi s i s due to t he f act t hat many f eat ures, whi l e hi ghl ydesi r abl e, ar e not essent i al . An exampl e of t hi s occur r ed dur i ng t he pr el i mi nar y desi gn st udi es. An ar t i cl e i n a t r ade magazi ne i ndi cat ed t hat $32m l l i on wer e avai l abl e for t he QSRA proj ect. The f i r st cost est i mat es, i nde-pendent l y prepared by t he t wo st udy contr act ors, wer e f or about 30 m l l i on.A speci al t r i p was made to NASA pr oj ect managers t o expl ai n t he di st r i but i onof f unds as shown i n tabl e 2. The second r ound cost est i mat es wer e about $20m l l i on. Bot h est i mat es wer e l egi t i mat e; t he di f f er ence was i n t he scope anddet ai l of t he t asks t o be accompl i shed.

W t hi n l i m t s, a proj ect such as QSRA can cost what you

Ther e i s, however , a l ower l i m t beyond whi ch a t echni cal l y meani ngf ulcost cannot be i mpl ement ed.compl et i on of t he QSRA pr oj ect wi t hi n t he avai l abl e f unds. These i ncl uded:(1) t he avai l abi l i t y of a sui t abl e ai r pl ane, t he deHavi l l and C- 8A, f or modi f i -cat i on; and (2) t he avai l abi l i t y of sui t abl e engi nes whi ch coul d be conf i gur edf or use i n t he QSRA.

Some f or t unat e ci r cumst ances cont r i but ed t o t he

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Airframe Acquisit ionThe C-8A w a s obtained a t no c os t, through app ro pr ia te government chan-n e l s, from th e Nat ion al C enter f o r Atmospheric Research (NCAR). The phys icals i z e and t h e T - t a i l co nf ig ur at io n of t h e 6-8A made i t an i d ea l a i r fr am e f o rmodif icat ion i n t o an advanced STOL a i r c r a f t and p r i o r ex p er i en ce w i t h a s i m i -

l a r mo dif ica tio n, t h e Augmented Je t Flap STOL Research Ai rc ra f t (AWJSRA),fur ther enhanced i t s d e s i r a b i l i t y .When t h e Fa ir ch il d A-10 ai rp la ne w a s s e l e c t e d as th e winner of th e UnitedSt a t e s A i r Force AX fly -of f comp etit ion, t h e two Northrop A-9A a ir p l a n e s weretr an sf er re d t o NASA fo r a pos s ib le f l i g h t r esearch p rogram. A l a t e r d ec i s i o nnot t o f l y th e two prototype ai r p l an es made th e engines , equipment, and spar esfrom t h i s p rogram av a i la b l e fo r QSRA us e. S i x Lycoming YF-102 en gi ne s andfour accessory power packages w e r e sa lv ag ed from t h e A-9A program to ge th erwi th many o t h e r mis cel lan eou s components. The YF-102 en gin es, a lth ou gh re la -t ively immature prototype engines , w e r e a lm os t i d ea l f o r t h e QSRA.high by-pass r a t i o , geared-fan engines th at generate 3 3 4 1 0 N (7,500 lb ) o ft h r u s t a t low no ise l eve l s .

They are

The use of the C-8A and th e YF-102 en gi ne s w a s an i mp or tant f i r s t s t e pi n min imiz ing th e cos t of th e QSRA pr o je c t , bu t many ad d i t io na l cost - reduc tionf a c t o r s w e r e necessary . They included: in-house pa r t ic ip at io n, cooperat iveapproach, de ta i l e d t r ack in g of co s t s , and a f u l l appre c ia t i on of th e impor-tan ce of co s t a t a l l o r g a n i z at i o n a l l e v e l s .

In-House Par t ic ipat ionThe approach to in -house par t i c ipa t ion w a s t o l e t NASA do t h a t whichNASA coul d do be s t and t o l e t Boeing do th os e t hi ng s which Boeing could do

be st . The lar ge- sca le wind-tunnel model i s an exc el le nt example of t h i s con-cept . Ear ly i n th e program, a la rg e- sc al e, powered wind-tunnel model w a si d e n t i f i e d as a pro jec t r equ i rement . Ames Research Center has a l o n g h i s t o r yof con s tru ct i ng lar ge powered models fo r research i n th e Ames 40- by 80-FootWind Tunnel. Boeing, on t h e o t h e r hand, had a de ta il ed knowledge of t hed e t a i l s of t h e QSRA design. I n o r d er t o t ak e ad vant ag e of t h e e x p e r t i s e ofeach o rgan iza t ion , Boeing w a s assigned th e ta sk of desig ning t h e model andNASA assumed re sp on si bi l i ty fo r f ab ri ca ti ng and instrumentin g t he model.Another example of a NASA in -house program w a s the engine program. Anext ens ive ground tes t program w a s completed by the L e w i s Research Center i nwhich both performance and ac ou st ic da ta w e r e acqu ired i n suppor t o f the QSRAd e s i g n e f f o r t .

f l i g h t en g i n e s .L e w i s a ls o managed th e program t o re fu rb is h and update t he

Cost ConsciousnessI t i s beyond t he scope of t h i s paper t o d i scuss t h e d e t a i l s o f QSRA man-agement beyond t h e examples t h a t have al re ad y been presen ted.d i scus s ion o f QSRA management would b e comp lete wit ho ut emphasizing t h eHowever, no

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importance of t h e outs tand ing coopera tion between th e Boeing pr oj ec t team andt h e NASA Pro jec t Of f ic e and th e de ta i l ed t r a ck in g of co s t s accompl ished byboth th es e groups. The Boeing pr oj ec t co nt ro l group t racked co s t f o r 38 workbreakdown s tr u c tu re elements on a weekly bas is a t t h e p eak of t h e p r o j e c t .These data were provided i n a t imely manner t o the NASA Pro jec t Of f ice andw e r e on d i s p l a y i n a control room i n th e Boe ing p r o j ec t area.p e rs o nn e l t o t h e l ow es t o r g an i za t i o n a l levels were made aware of co st pe rfo r-mance. The NASA P r o j e c t O f f i c e w a s consul ted whenever t ra ns fe rs w e r e madefrom t h e Boeing management re se rv e.expended t o co rre ct minor performance d ef ic ie nc ie s th a t w e r e not impor tan t t oNASA, and av ai la bl e resou rces could be concentra ted on important problems. .

Thus , project

I n t h i s way, p r o j ec t f u nd s were not

A paper p lanned for l a t e r publ i ca t io n by t h e QSRA pro jec t per sonne l w i l ld e a l wi th t h i s s u b j e c t i n d ep th .

IN-HOUSE PROGRAMS

Wind-Tunnel TestsThe need f o r acc ura te , large-sca le , wind- tunnel te s t in g of t h e s p e c i f i cp ow er ed -l if t a i r p l a n e co n f i g u r a t i o n had b een i d en t i f i e d i n s t u d i e s pr evi o ust o t h e QSRA con tra ct award ( re f . 4 ) . I n o r d e r t o s up po rt t h e QSRA des igne f f o r t , a nd t o re du ce c o s t s and r i s k by u t i l i z i n g NASA t a l e n t and f a c i l i t i e s ,an e xi st in g larg e-sc ale, wind-tunnel model w a s modified t o be aerodynamicallys imi l a r t o t h e QSRA and t e s t e d i n t h e Ames 40- by 8O-Foot Wind Tunnel . T h i s0.55-scale model w a s used t o provide aerodynamic and loads da ta f o r th e QSRAdes ign, and t h e c o n t r o l s t a b i l i t y d a t a f o r t h e f l i g h t s im u la t io n program.Wind-tunnel model-The QSRA wind-tunnel model i s shown mounted i n t h e

Ames 40- by 8O-Foot Wind Tunnel , i n fi g u r e 2 . Th is model i s powered by fiveJT-15D t ur bo fa n eng ine s.th e f i f t h , mounted i n the fuse lage , p rovides boundary- layer con t ro l (BLC) a i r .The model ha s th re e tra ili ng -ed ge f l a p systems. Upper-surface-blown f l a p s areloca t ed d i re c t ly beh ind th e eng ines, w i th doub le - s lo t ted f l ap s ou tboard ofth es e and blown a i l er on s a t th e wing t ip s . The e n t i r e lead ing edge i s blownfo r boundary- layer con t ro l , inc lud ing the area between th e nac el le and fuse-lage. Although th e leading edge f l ap s were f i x e d , t h e t r a i l in g - e d g e f l a psys tems and spoi lers cou ld be r emotely a c tua ted dur ing th e t e s t runs.

Four of t he se engines are mounted above t h e wing;

This model had over 600 pre ssu re and temperature measur ing poi nt s i nEnginerder t o prov ide a i r lo ad s and tempera tu re des ign da ta f o r t he QSRA.t h r u s t levels w e r e measured ynder s t a t i c condi t ions wi th f la ps up and corre-l a t e d w i t h f an s p eed.t h r u s t levels during t h e wind-tunnel test poin t s . The cor re c ted mass flowsw e r e obtained f rom ideal m a s s f lows , ca l cu l a te d by us ing t he average s t a t i cp r e s s u r e a t th e f a r t he s t downstream i n l e t measur ing po in t and th e tes t s e c t i o nt o t a l t empera ture and p res sure . Th is id ea l f low w a s c o r r e c t ed f o r p r e s s u rerecovery and i n l e t lo sse s by assuming a 0.98 c o r r e c t i o n f a c t o r .

These cor re la t i on equa tions were used t o determine

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Ai r cr af t desi gn cont r i but i ons- The w nd- t unnel t est s of t hi s model madea number of i mpor t ant cont r i but i ons t o t he f i nal QSRA desi gn.def i ned the ai r l oad dat a used i n t he QSRA st r uct ur al desi gn, show ng t hatt hese l oads wer e sl i ght l y di f f er ent i n l ocat i on and magni t ude t han those pr e-di ct ed usi ng YC- 14 dat a, par t i cul ar l y on t he f usel age near t he w ng l eadi ngedge. These t est s al so ver i f i ed the m xed f l ow nozzl e and pr opul si on syst emsi mul at i on whi ch was based on Langl ey J T- 15D t est s si mul at i ng t he YC- 14 pro-pul si on system The t est s def i ned t he BLC syst em r equi r ement s, show ng thatbl ow ng was necessar y at al l t i mes al ong t he l eadi ng edge dur i ng hi gh angl e-of - at t ack oper at i ons, r esul t i ng i n a redesi gn of t he QSRA s BLC syst emt est s def i ned and ver i f i ed t he ef f ect i veness of t he cont r ol sur f aces and t heef f ect s of engi ne- out and ot her f ai l ur e condi t i ons, pr ovi di ng a dat a base f ort he f l i ght si mul at i on. Fi nal l y, t hese t est s def i ned a ser i ous nacel l e/ w ngaer odynam c i nt er f er ence pr obl em and pr ovi ded a si mpl e, ef f ect i ve, l ow- costsol ut i on f or t he ai r craf t desi gn, by show ng t hat sever al smal l vor t ex gener -at or s coul d el i m nat e t he boundar y- l ayer separ at i on at t hi s i nt er f ace. A mor edet ai l ed summary of t he test dat a i s cont ai ned i n r ef erences 5- 7.

These tests

These

Conf i gur at i on opt i m zat i on- A cont i nui ng benef i t of t hese w nd- t unnelt est s i s i n t he use of t hi s dat a base and t he model as a t ool f or f ur t her con-f i gur at i on devel opment and opt i m zat i on. As an exampl e, t he ear l y w nd- t unnelt est s showed t hat al t hough bl ow ng was essent i al al ong the l eadi ng edge athi gh angl es- of - at t ack, onl y ver y smal l amount s wer e r equi r ed t o keep the f l owat t ached over t he w ng. I n subsequent t est s, a sl ot t ed l eadi ngedge f l ap wasf abr i cat ed and test ed to determ ne what per f ormance penal t i es, i f any, wer eassoci ated wi t h r emovi ng t he out boar d l eadi ng edge BLC syst em ( ref . 5.Al t hough perf ormance i mpr oved sl i ght l y, t her e was a l oss of about 4 i nangl e- of - at t ack mar gi n. One of t he pr oj ect ed st udi es to be made wi t h t heQSRA wi l l be to ver i f y i n f l i ght t he ef f ect of r epl aci ng t he out boar d l eadi ngedge BLC sys t em wi t h a sl ot t ed f l ap, a change that woul d consi der abl y si mpl i f yt he ai r craf t pneumat i c system Thi s change wi l l be made, however , onl y af t era t hor ough document at i on of t he f l yi ng char act er i st i cs of t he basi c conf i gur a-t i on.

Engi ne Gr ound Test sAs di scussed pr evi ousl y, t he QSRA i s powered by t he Lycom ng YF- 102engi nes acqui r ed f r om t he A- 9A ai r craf t pr ogr amt i vel y i mmatur e pr ototype engi nes, t hey had met al l of t hei r perf or mance goal sdur i ng the AX pr ogr am and had demonst r at ed oper at i onal r el i abi l i t y.however, r equi r ed a much mor e compl ex engi ne i nst al l at i on wi t h a conf l uentf l ow exhaust syst emand wi t h a bl eed ai r schedul e r equi r i ng up to 10%of cor eai r f l ow at l ow power set t i ngs. These QSRA r equi r ement s wer e so f ar beyond

t he exi st i ng engi ne per f ormance data base t hat t her e wer e quest i ons r egardi ngengi ne oper at i on and i t s ef f ect on cost and ai r craf t saf et y.ambi t i ous acoust i c goal s of t he QSRA r equi r ed an ext ensi ve acoust i c dat a basei n order t o devel op an adequat e l ow- noi se nacel l e desi gn wi t hi n cost con-strai nts . I t became obvi ous t hat i t was necessar y t o devel op these dat a basesi n or der to m ni m ze pr ogr am cost and r i sk, and agai n i t was cl ear l y an areawhere NASA t al ent and f aci l i t i es coul d be used most ef f ect i vel y.

Al t hough t hese ar e r el a-The QSRA,

I n addi t i on, t he

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Vert ica l Lif t Fan Faci l i ty-The L e w i s Research Center V er t i ca l L i f t FanThe engine i s suspended beneath the

F a c i l i t y i s an outdoor engine t e s t s t an d s h e l t e r e d by a service bui ld i ng whichi s moved away on tr ac ks be fo re t e st in g.th ru st measuring system, which can be piv oted around a v e r t i c a l ax is fo r oper -a t i o n a l f l e x i b i l i t y . A frame work ext ending from t he t h ru s t measuring systemi s used t o mount i n l e t and exhaus t hardware s ep ar at e l y from th e engine.en g i n e cen t e r l i n e was 2.9 m ( 9. 5 f t ) abo ve t h e grou nd; t h e f a c i l i t y , w i t h t h eba se li ne confl uent f low YF-102 mounted on th e th ru st s t an d, i s shown i n f ig ur e3 . The area beneath t he engine i s paved wi th concre te and asp ha l t ou t t o t h eac ou st ic d at a microphones which are located on a 30-m (100 f t ) r a d i u s c i r c l eover a 160 ar c from th e i n l e t cen te r l in e . The co n t ro l room i s loca ted abou t152 m (500 f t ) f rom th e s tand and af fo rd s a good view of t h e e ng in e i n l e t . '

The

ProDulsion desi gn refinements-The engi ne ground t e s t c o n tr i bu t e d t o t h ef i n a l QSRA a i r c r a f t d e si gn i n a number of d i f f e r e n t ways. The tests wereused t o def ine t he engine base- l ine performance f or t he conf lue nt f low conf ig-ur at io n and t o update t he engine performance pre di ct io n deck.d e fi n ed t h e t r a n s i e n t o p e r a t i n g c h a r a c t e r i s t i c s of t h e en g in e and t h e e f f e c tof BLC s ys tem f a i l u r e s on t h e en g i ne s t a b i l i t y and s a f e o p e ra t i on .t e s t s showed th a t t he engin e w a s unable t o acc el er at e from low power se t t in g sunder h igh cor e b leed cond i t ions , r eq u i r ing th e des ign o f a BLC con t ro l sys temt h a t l i m i t s core b leed t o power se t t in gs where th e eng ine can be s a f e l y oper-a t e d . New acceptance t e s t procedures w e r e developed as a r e s u l t of t h e s eground tests i n o r d e r t o en s u r e adequ at e, s t a b l e , and s a f e en gi n e op e r a ti o nwhen i n s t a l l e d i n t h e QSRA. F i n a l l y , a s p e c i a l t e s t w a s ru n t o v e r i f y t h edes ign and adequate operat ion of th e fan bleed a i r S-duct and i t s flow char-a c t e r i s t i c s a t t h e e j e c t o r i n l e t ( r e f . 8 ) .

These t e s t sThese

Aco usti c desi gn refinements-Acoustic performance i s a second area wheret h e L e w i s t e s t program made s ig n i f i ca n t co n t r ib u t ion s t o th e QSRA design.These tests developed a l l of th e ac ou s t i c da ta base fo r th e YF-102 engine,providing a measure o f th e component no is e l e ve l s and t h e i r d i r e c t iv i t y .i n du c t f a n t on es and t h e i r l o c a t i o n r e l a t i v e t o t h e d u ct w a l l s w e r e determinedalong with t h e i r mode shapes and oth er de s ign data . Acous t ic des ign s impli -f i c a t i o n s e l i m i n a t i n g s p l i t t e r r i n g s and eng i ne sp i n ne r t re a tm ent w e r e ver i-f i ed , e l im ina t i ng cons iderab le cos t and per fo rmance pena l t i e s . The e f fe c t ofwing sh ie ld ing w a s determined and , f i na l l y , sp ec ia l t echniques w e r e developedt o dete rmine t he con t r ibu t ion o f combustor no ise ( r e f . 9) .

The

F l ig h t S imulat ionThe Ames Fl ig ht S imulator f o r Advanced Ai rc ra f t (FSAA) w a s used tod e f i n e t h o s e co mb in at io ns o f f l i g h t co n d it i o ns , a i r c r a f t co n f i g u r a t i o n , con-

t ro l power , and con t ro l rates t h a t w ould en su r e accep t ab l e h and l in g q u a l i t i e sfo r bo th normal opera t ion and i n var ious s i n g l e o r m u l t i p l e f a i l u r e oc cur-r en ce s i n e i t h e r p r op u ls io n o r f l i g h t c o n t r o l s yst em s.FSAA-The FSAA i s a six-degree-of-freedom motion simu la to r wi th very highf i d e l i t y m ot io n and v i s u a l cu e s.

observer i n t he cab.t has two p i l o t s t a t i on s and room fo r an

t w a s co nf ig u red t o c l o s e l y app ro xi ma te t h e f l i g h t

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deck of t he QSRA wi t h s i m l ar i nst r ument s, t hr ot t l es and cont r ol s.eye vi ew of t he si mul at i on i s shown i n f i gur e 4.has shown that r eal i st i c, accur at e si mul at i ons can be made and, i ndeed, t hepi l ot r at i ngs of 2- 3 f or normal oper at i on at l ow speed and 4-5 f or a s i ngl ef ai l ure wer e ver i f i ed i n f l i ght .

A pi l ot ' sExper i ence wi t h t he FSAA

These si mul at i ons showed a need f or severaldesi gn changes t o i mpr ove handl i ng qual i t i es under a var i et y of STOL operat i onsand si mul at ed f ai l ur e condi t i ons.t at i on and di r ect l i f t cont r ol was i dent i f i ed, as was a change i n hor i zont alstabi l i zer i nci dence.t i on of t he upper surf ace bl own f l aps t o r educe drag dur i ng go- ar ound.pr ocedur es and handl i ng qual i t i es wer e al so def i ned f or oper at i ons w t h oneor more engi nes i noperat i ve, and f or si t uat i ons wher e el ect r i cal power wasl ost , or hydr aul i c or boundar y- l ayer cont r ol systems had f ai l ed. St eep cur vi -l i near l andi ng appr oach operat i ng pr ocedur es wer e i nvest i gated f or noi seabat ement .

The need f or l ongi t udi nal st abi l i t y augmen-A r equi r ement was al so det er m ned f or aut omat i c ret r ac-Pi l ot

Fur t her det ai l s of t he QSRA f l i ght si mul at i ons, t he QSRA mat hemat i calmodel , and the r esul t s of t hese si mul at i ons ar e cont ai ned i n r ef er ences 10- 12.AI RPLANE DESCRI PTI ON

The gener al ar r angement of t he QSRA i s shown i n f i gur e 5 and a phot ogr aphof t he ai r pl ane i s shown i n f i gur e 1. The f usel age i s t hat of a deHavi l l andC8-A Buf f al o wi t h st r uct ur al r ei nf or cement i n t he af t f usel age and new f ai r -i ngs at t he w ng- body i nt er sect i on.t ur al or aer odynam c modi f i cat i on.and t he el evat or and a hydr aul i c actuator was added f or power act uat i on of t heel evat or .bi l i ty of the ai rcraf t .

The C-8A empennage was used w t hout st r uc-SAS act uat ors wer e added to bot h t he r udderThe C-8A l andi ng gear was modi f i ed t o i ncr ease t he si nk r at e capa-

22ofThe QSRA w ng was desi gned and f abr i cated bz Boei ng wi t h a w ngspan of

.4 m (73. 5 f t ) , a w ng area of 55. 74 m2 (600 f t > , nd a quar t er chor d sweep15O. Fi gure 6 shows t he w ng bei ng at t ached to the f usel age at t he Boei ngDevel opment Cent er i n Seat t l e. The cent er sect i on of t he w ng i s seal ed t of or m t wo i nt egr al f uel cel l s whi ch cont ai n a t ot al of 4535. 9 kg ( 10, 000 l b)of J et A-1 ( J P- 5) f uel . Fi xed l eadi ng edge f l aps ar e bl own by a m xed f l owboundar y l ayer cont r ol systemt er l i ne consi st s of t wo upper sur f ace bl ow ng ( USB) f l aps, a doubl e- sl ot t edf l ap, and a dr ooped, bl own ai l er on.The t r ai l i ng edge on ei t her si de of t he cen-

The f l aps and ai l erons ar e suppor t ed by external beams and l i nkages.The mai n l andi ng gear i s f i xed and i s

I nkeepi ng w t h t he aust ere nat ure of t he pr ogr am and t he l ow- speed envi r onmentof t he QSRA, t hese ar e not f ai r ed.at t ached t o t he unders i de of t he w ng between the t wo nacel l es. The w ng i sat t ached t o t he f usel age by t he same pi n j oi nt s as t hose used i n the or i gi nalC-8A.of 4 1 8 . 7 kg ( 923 l b) of bal l ast i n t he tai l .Thi s pr ovi ded a si gni f i cant cost savi ng but i t di d r equi r e the addi t i on

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Propul si on SystemThe QSRA mai n pr opul si on syst em consi st s of f our AVCO- Lycom ng YF-102(QSRA) engi nes mount ed i n above- t he- w ng nacel l es (f i g. 5. These pr otot ypeengi nes, acqui r ed f r om t he A-9A pr ogr am wer e ext ensi vel y ref ur bi shed andupdated i n a pr ogr ammanaged by t he Lewi s Resear ch Cent er. The pr i nci pal

el ement s of t hi s updat e i ncl ude a f an cont ai nment r i ng, combust or case hi gh-pr essur e ai r bl eed por t s, new oi l cool er s, and i mpr oved shaf t i ng mat er i al .Power pl ant - A cut away vi ew of t he engi ne i s shown i n f i gur e 7. The l ow-pr essur e spool i ncor por at es a si ngl e- st age f an whi ch pr ovi des bypass and cor e,ai r t o t he engi ne.super charger at t ached t o t he f an. The f an i s dr i ven by a two- st age, uncool edt ur bi ne t hr ough a si ngl e pl anet ar y r educt i on gear (2.3 speed rat i o) l ocat edi n the f an modul e.

The core ai r f l ow i s f ur t her compr essed by a si ngl e- st age

The gas pr oducer sect i on of t he engi ne i s essent i al l y a T- 55 cor e wi t hsl i ght modi f i cat i ons.gal compr essor , a r ever se- f l ow combust or , and a two- st age, ai r - cool ed t ur bi net o dr i ve t he compr essor. The hi gh- pr essur e compr essor has seven axi al st agesf ol l owed by a cent r i f ugal st age.(VI GV' S) and a si xt h- st age bl eed band to m ni m ze the possi bi l i t y of compr es-sor st al l duri ng tr ansi ent operati ons.

The hi gh- pr essure component s i ncl ude an axi al / cent r i f u-I t f eat ur es var i abl e i nl et gui de vanes

The engi ne wei ghs 5412 N (1215 l b) and has a basi c di ameter of 1.077 m(42.4 i n. ) wi t h an over al l l engt h of 1.621 m ( 6 3 . 8 i n. ) i ncl udi ng t he f anspi nner , whi l e t he f an has a di amet er of 1.024 m ( 4 0 . 3 i n.). The engi ne geomet r y and unst al l ed perf ormance are shown i n f i gur e 8.Nacel l e st r uctur e- The nacel l e l ayout i s shown i n f i gur e 9 and t he maj orexter nal nacel l e st r uct ur al component s ar e shown i n f i gur e 10. The exter nal

nacel l e i s composed of t wo mai n assembl i es, t he st r uct ur al cow and nozzl eassembl y and the engi ne bui l d- up assembl y. The st r uct ur al cow and nozzl eassembl y i s at t ached to t he w ng f r ont s par, f or m ng t he st r uct ur al nacel l eand pyl on. The engi ne bui l d- up assembl y i s t hen mount ed t o thi s st r uct ur eand f or ms t he f r ont hal f of t he nacel l e. The nose cowl i s at t ached t o t heengi ne as shown i n f i gur e 1 1 and f orms t he i nl et and out er nacel l e.t i on to t he nose cowl , a cor e cow and t he pr i mar y nozzl e are i nst al l ed aspar t of t he engi ne bui l dup.i n t he nose cowl , r esul t i ng i n thi s area bei ng one of t he t hr ee pr i mar y f i r ezones i n t he nacel l e. Ot her f i r e zones ar e t he core cavi t y and the out er f ancase.shi el d at t ached to the upper surf ace of t he wi ng, t oget her wi t h t he use ofheat - r esi st ant mat er i al s i n t he w ng f l aps and t r ai l i ng edge.t he pr i mar y nozzl e i s cant ed bpwards al l ow ng cool i ng f an ai r t o be dr awnbetween t he w ng sur f ace and t he hi gh- t emperat ur e j et i n nor mal oper at i on.

I n addi -Engi ne dr i ven accessor i es ar e ai r f r ame- mount ed

Fi r e pr ot ect i on behi nd t he nacel l e i s pr ovi ded by an exter nal heatI n addi t i on,

Exhaust nozzl e- The QSRA/YF-102 exhaust system i s a conf l uent - f l ow desi gnwi t h bot h pr i mary and f an st r eams di schar gi ng t hrough a common D- shaped exi tnozzl e havi ng an aspect r at i o of 3. 5. As i ndi cat ed i n f i gur e 12, t he cor eexhaust di f f uses as i t passes t hr ough t he pr i mar y nozz l e and t hen m xes wi t h9


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the surrounding fan stream, e x i t in g through th e D-shaped upper-surfa ce blowingnozzle .l i n e t o m in im ize t h e h e a t e f f e c t s on t h e wing and f l a p s .The core nozzle i s canted upward 9.4' re l a t iv e t o the engine center -

The flow areas i n th e fan-duct and core-nozzle e x i t p lane (mixing plane)The main c o n tr o l on su rg e margins and engi ne match, however,

are chosen t o p rov ide adequa te performance wi thou t s ig n i f i ca n t ly a f f ec t i ngsurge margins.i s p ro vi de d by t h e f i n a l e x i t area of t h e D-nozzle, which i s des igned tospread the exhaus t in t o a th in shee t , which i s then turne d by t h e Coandaef fe c t over the USB f l ap s , p rov iding l i f t .

The QSRA D-duct de sig n ha s mixing pla ne areas of 0.44 m2 (682.5 in.2) and0.156 m2 (250 i n . 2 > f o r t h e f an and co r e airstreams, re sp ec ti ve ly . The D-nozzlew a s designed s o t h a t t h e e x i t area could be increased as much as l o % , if needed,from an e f f e c t i v e area of 0.42 m2 (650 in.2) which w a s 7.5% under t h e assumedb a s e l i n e area. Subsequent ca lc ul at io ns showed t h a t th er e would be adequate surgemargins a t t h i s area, however, and t h a t no noz zle t r i m would be needed. Measuredr e s u l t s di sc us se d i n a l a t e r sec t io n showed tha t indeed t h i s w a s t h e case.Acoust ic t reatment -The loc a t i on o f th e na ce l le aco us t ic l in e r s i s showni n f i g u r e 12. These l i n e r s are l o c a t e d i n two d i f f e r e n t n a c e l l e areas, t h efan duc t and the in le t . The fan duc t l in e r s , which are loca t ed on bo th th es t ru c tu ra l cowl and on th e core cowl, are composed of perforated aluminumf a c e s h e e t s bonded t o a n aluminum honeycomb core with solid aluminum outerbacking sh ee ts . These pane ls cover about 0.75 m (30 i n . ) of duct length and arees t imated t o p rov ide abou t 1 2 PNdB of a f t fan a t te nu at io n. These panels serv eas an i n t eg r a l p a r t of t h e cowl s t r u c t u r e and are l oad- ca rr yi ng i n ad d i t i o n t oproviding sound at tenuat ion.The second area of t h e n a c e l l e t h a t i s l i n e d i s t h e i n l e t . The i n l e taco u s t i c p an e l s a re double- layer con s tru ct i on with pe rfo rat ed a luminum face

sheet and septum with aluminum honeycomb cores and a solid aluminum backingsh ee t. The lower aco us ti c pane l honeycomb co re s are s l o t t e d and d r a i n h o l e sare p ro vi de d i n t h e o u t e r s h e e t t o p revent water accumulation and possiblefr e e z e damage.

BLC SystemA unique fea t u r e o f t he QSRA i s t he mixed-flow boundary-layer co nt ro l

(BLC) system fo r t he wing lea ding edges and ai le ro ns .i s bled from both th e f an and t he engine core and mixed i n an e je c t o r .schematic of t h i s sys tem i s shown i n f i gu re 13.A i r f o r t h e BLC systemA

The BLC a i r i s di s t r i bu te d by cross-duct ing f rom each engine t o the oppo-s i t e s i de of th e wing lead ing edge o r a i l e ro n su r fac es .ducting and check valves are in s t a l l e d be tween t he two BLC system manifolds;they are loca t ed ex te rn a l l y under th e wing ou tboard of th e ou tboard n ace l l es .The a i l e ro n duc ting i s l o c a t e d i n a c a v i t y a f t of t h e rear s p a r ; however, theleading edge ducting had t o be lo ca ted ex te r na l ly behind th e l ead ing edgef l ap s and c r o s s e s ov er i n s i d e t h e f u s e l ag e , under t h e wing.

Interconnect ing

A s w a s previous ly

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discussed , these duc t s may be s impl i f i ed , i n a f u t u r e t e s t p e r io d , t o e l i m i n a t esome of th e ex te rn al ducts . The BLC duc t ing i s arranged so that each enginefeeds a s ep a r a t e p a r t of the BLC system, as shown i n t a b l e 3 . This arrangementprovides a degree of au tomat ic r o l l compensa tion i n th e even t of the los s ofa c r i t i c a l ( ou tb oa rd ) eng in e.Key elements i n t he BLC system are the mixing ejector and servo-regulatorThe ejector , which i s shown i nalve which are l o ca t ed as shown i n f ig ur e 1 4 .t h e i n s e r t of f i g u r e 15, has a f ixed-geometry mixing se ct io n wit h an e l l i p t i c a lce nt er body, and 42 c i r cu m f e r en t i a l l y d i s t r i b u t ed e j e c t o r n o zz le s . Th eseconvergent-divergent nozzle s , wi th length- to-diameter ra t i o s of 5:1 l i m i t .the h igh-pres sure b leed to a nominal 10%of t he engine core f low; and fan bleed

i s l i m i t e d t o 3% d ue t o d u c t s i z e . F i g u re 15 shows t h e e f f ec t of t h i s e j e c t o rdesi gn on ne t blowing momentum of t he a i le ro n no zzl es. The upper curve repre -se n t s the performance of the e j ec to r wi thout any p res sure r egu la t ion .se rvo- regu la to r va lve l i m i t s the downstream duct pressure t o a preset va lue ,however, and th e regul ate d system follo ws the lower curve of f ig ur e 15, y ie ld -i n g a ne ar ly con stant v alu e of blowing momentum over t he e n t i r e engine thr us trange. This valve re gul ate s h igh-pressure f low f rom th e compressor so t h a t i ti s zero a t high power se t t in gs where the f an p res sure r a t i o i s high, and about10%of t h e co r e a i r f l o w a t low power se tt in g s. Although th er e i s a l o s s i nen g i n e t h r u s t a t t h e 10%b l eed a i r f l o w , i t only occurs when a low-thrus t leveli s commanded by the p i l o t . A t h ig h -t h ru s t s e t t i n g , t h e t h r u s t l o s s i s l essthan 1%d u e t o BLC system losses.

The

F l i g h t C o n t ro l sThe f l i g h t c o n t r o l s u r f ace s are shown schematical ly i n f ig ur e 16. A l lwing t r a i l i n g ed ge s u r f ace s are e l ec t r i c a l ly con t r o l led ( fly-by-wire) exceptt h e a i l e r o n s . The sp oi le rs , double-s lo t ted f l ap s , and USB f l ap s are e lec-

t r i c a l l y commanded and hydr aul ica l ly powered; th e a i le ro ns are mechanicallycon tro l le d and hyd rau l ic al l y powered. Both the rudder and ele vat or ar e C-8Acomponents which are mechanical ly control led and both are hy dr au li ca ll y pow-ered.Fla p system-The USB f l a p s are dep loyed t o th e 30 p o s i t i o n w i th t h ep i l o t s f l a p l e v er . A thumb s w i t ch lo ca t ed i n t h e t h r o t t l e h an dl e f o r t h e

No. 1 engine co nt ro ls USB fl a p po si t i on from 30 t o t h e f u l l d e fl ec t i on of66O. This provides t h e p i l o t w i t h a convenient means of varying USB f l a ps e t t i n g , d u r i n g a landing approach, as a means of gl id e path cont rol . Deploy-ment of th e double-s lo t te d f l a ps i s con t ro l led by a s ep a r a t e l ev e r o n t h ep i l o t ' s co n s o l e . The ai leron droop i s s l av ed t o the double - s lo t ted f l aps .The USB f l a p s , t h e s p o i l e r s , and t h e d ou b l e -s l o tt ed f l ap s are a l l i n d i v i d u a l l ya c t ua t e d by d i g i t a l , e l e c t r o n i c a l l y c o n t r o ll e d , h y d r a ul i c a c t u a t o rs . T h isa l lows any f l ap o r sp o i le r t o be ac tua ted independen t ly of any o ther by p roperpreprogramming. This fe at ur e provides maximum res ea rch c ap ab il i t y fo r t h eQSRA. A s i n i t i a l l y co nf ig ur ed , t h e QSRA p i l o t h a s t h e c a p a b i l i ty t o commandassymetric deployment of the double-s lo t ted f l ap s t o t r i m eng ine-ou t ro l l ingmoment.

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S t a b i l i t y augmentat ion sys ten-The QSRA has a s i ng le channe l , th ree-ax isl i m i t e d a u t h o r i t y series t y p e s t a b i l i t y aug ment at io n sys tem (SAS). The r o l land yaw axes are s t a b i l i z e d by a s i m p l e analog system s i m i l a r t o th e one usedi n t h e Augmented J e t Fla p STOL Resear ch Airp lan e. The lo n g i t u d i n a l SAS i s arate-command, at ti tu de -h ol d system. t uses a General Elec t r i c MCP-701A di g i -t a l computer t o p ro v id e b o t h p i t c h SAS f u n c t i o n s and t o co n t r o l t h e d i r ec tl i f t co n t r o l s ys tem and ce r t a i n o t h e r l o g i c f u n ct i o ns . When t h e d i r ec t l i f tco nt ro l (DLC) fun ct io n i s s e l e c t ed , t h e s p o i l e r s are deploy ed t o ab out -13'.An i n c r e a s e i n t h r u s t ( t h r u s t levers forward) c au se s t h e s p o i l e r s t o r e t r ac t ,and a dec rease i n th r u st ca uses them t o extend beyond th e nominal -13' angle.Aft er each excurs ion from th e -13' po s i t i on , a washout c i r c u i t g radua llyr e t u r ns t h e s p o i l e r s t o t h e -13' p o si ti o n u n t i l t h e t h r o t t l e i s once againmoved. A t go-around thrust levels , t h e DLC system i s au tomat ica l ly d i sab ledand t h e s p o i l e r s are r e t r a c t e d .

Addi t ional informat ion on the QSRA configuration and systems i s containedi n r e f e r en c e 13.

AIRCRAFT PERFORMANCE

Although a la rg e number of ground and f l i g h t t e s t s have been performed t ode te rmine the QSRA s opera t ing cha ra c t e r i s t i cs , many o f the se da ta a r e s t i l lbeing analyzed a t t h i s wr i t in g . Therefo re, many of th e a i r c ra f t per fo rmancecurves presented are based on pre dic ted , wind- tunnel , or s imulat ion res ul ts .Most of t h e ground t e s t da ta have been analyzed, however, allowing a compari-son of th e pre dic ted and measured Ch ar ac te r i s t i cs of th e propuls ion and BLCs yst em s. I n a d d i t i o n , s u f f i c i e n t f l i g h t d a t a have been checked t o ve r i fyth a t th e a i r p la ne per fo rmance i s c l o s e t o t h a t p r e d i c t e d , a nd t h e s e f l i g h tr e s u l t s w i l l be commented on i n t h e p r e s en t a t i o n o f t h e i n d i v i d u a l d a t a cur v es .

Propulsion SystemMost of th e measurements of propuls ion sys tem ch ar ac te r i s t ic s w e r e made

(1) t o determine t he component map ch ar ac te r i s t ic s and t o ve r i fy ade-duri ng t h e Boeing ground t e s t . The primary ob je ct iv es of t h i s ground t e s tw e r e :qua t e su rge margins (nozz le t r i m) ; (2) t o measure engine performance with andw i t h o u t t h e BLC sys tem operat ing; ( 3 ) t o t r i m and ad jus t th e eng ine fu e l con-t r o l s f o r i d l e , t akeo ff power, and accept ab le a cce l e r a t i o n ch a r ac t e r i s t i c s ;and, ( 4 ) t o measure f laps-up th ru s t and f laps-down turning. I n order to m e e tt h e s e o b j e c t i v e s , a la rg e number of da ta poi nt s w e r e taken and analyzed foreac h eng ine ; however, it w i l l o nl y b e p o s s i b l e t o p r e s e n t a s m a l l representa-t ive sample of t h e da ta here. Four summary p l o t s w i l l be presented.d e a l w it h e n g in e t h r u s t r e l a t i o n s h i p s , one wi th th e loc a t i on of th e eng ineopera t ing l i ne s on th e f an map, and the fo ur t h wi th th e acce le r a t i on charac-t e r i s t i c s of t h e en gi n es w i t h t h e BLC bleed schedule.

Two

Thrus t charac te r i s ti cs -The re l a t i ons h ip o f th e eng ine th ru s t w i th f anspeed i s shown i n f ig ur e 1 7 , which a ls o shows th e re la t i on sh ip between fanand core speed fo r these eng ines . Th is curve i s based on th e ground t e s t12


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r e s u l t s o f a l l four of t h e eng i ne s ( t h e r e s u l t s had less than t l c a t t e r ) .The c or re la t i on between t he pr edi cte d performance i s very good above 7 2 % ofthe cor rec ted core speed bu t very poor a t lower core speeds ; hence, t h i s curveg iv e s b e t t e r r e s u l t s than computer deck and w i l l be used fo r performance e s t i -ma tion i n t h e f l i g h t t e s t program. As measured i n th e ground t e s t , t h e i n -board engines have about 3% less i n s t a l l e d t h r u s t t h an t h e o ut bo ar d en gi ne swhich have a maximum i n s t a l l e d t h ru s t of 30,068 N (6 ,750 lb) .ambient temperature a t sea level on t h i s maximum i n s t a l le d th ru s t i s shown i nf igure 18 .because t he h igh p re s sure b leed i s normally shu t of f a t t h i s power s e t t i n g .One add i t iona l i t e m t o n o te i s t h e r e s t r i c t ed zon e shown i n f i g u r e 1 7 . T h i s ,r e s t r i c t i o n r e s u l t s from a resonance problem i n t he sun gear a t a fan speedof 55.5%.at in g band ha s been se t between 50 and 60% t o preve nt exce ssive excursion sin to th i s zone, pa r t i c u l a r ly near the r esonance peak. Th is band causes ab a s i c p roblem i n t h e a i r c r a f t operat ion by fo rci ng th e STOL f l i g h t i d l e set-t i n g t o be a t a nomin al 60% which i s about 5-6% hig her than i s d es i r ab l e .AVCO-Lycoming i s working on a r ed es i g n of t h e su n g ea r t o e l i m i n a t e t h i sresonance problem and ex pect s t o have a so lu t i on some t i m e i n 1979.

The ef fe c t ofThese takeoff da ta are shown f o r no-bleed and ECS-bleed on ly

Although t h i s resonance has a very sharp peak , the r e s t r i c t ed oper-

Fan ope rati on-F igu re 19 shows t e s t data from a l l four eng ines p lo t tedon t h e YF-102 f a n map. This map includes pre dic ted operat ion f o r a range ofr e l a t i v e n oz zl e areas w i t h t h e b a s e area correspon ding t o t h e untrimmed noz-z l e s .bypass flow as pr imary parameters with corrected fan speed as a secondaryparameter.fa n speeds of 70%; a t h i g h e r s peeds , t h e s e d a t a i n d i ca t ed a nozzle under-areacond i t ion of u p t o 2 . This nozzle area spread w a s cons idered good i n l i g h to f t he r a th er l i m i t ed ins t rumentat ion and hence a d ec i s i o n w a s made t o oper-a t e w i th o ut ad d i t i o n a l n o zzl e t r i m . The upper l i m i t f o r fan operat ion useddu ri ng th e A-9A program's YF-102 ac ce pt an ce t e s t s i s a l s o shown i n t h e f i g u r ef o r r e f er en ce.

The t e s t d a t a w e r e p l o t t e d u s in g f an p r e s s u r e r a t i o and co r r ec t edThe t e s t d a t a i n d i ca t ed good co r r e l a t i o n w i t h p r ed i c t i o n s up t o

Engine accelerat ion-Engine ac ce le ra t i on s w e r e i n i t i a l l y con du ct ed on a l le n g i n e s s t a r t i n g a t t h r e e fa n speeds-48, 53, and 60%-which encompassed t h epr ed ic te d STOL f l i g h t i d l e range. Adjustments w e r e made, t o t h e f u e l co n t r o l sof a l l t h e e n g in es , t o i n c r e a s e t h e a c c e l e r a t i o n sc h ed u le i n o r de r t o i n c r e a s et h e a c c e l e r a t i o n r a t e wi th t h e Boeing high-pressure blee d schedule. Figu re 20shows the th ru s t ver su s t i m e f o r a c ce l e r a t i o n s from 53% f an speed fo r a l l t h ee ng in es w i t h t h e f i n a l f u e l c o n t r o l a dj us tm en t. A l l of t h e eng i ne s a cc e l e r a t et o 65% t h r u s t i n app ro xi ma te ly t h e same t i m e ; however, from t ha t poin t onengine N o. 2 w a s markedly slower and took se ve ra l more seconds than th e oth erengines t o come up t o th e 95% th ru s t p oin t . This s lowness i s due t o a n i n t e r -a c t i o n w i t h t h e BLC system, where t h e valve on engine No. 2 b eg in s t o c l o s e a ta higher speed and appears t d c l o s e a t a slower rate. T hi s r e s u l t s i n h ig he rb leed rates a t a given fa n speed fo r engine No. 2 which reduces the accelera-t i o n r a te a t high er fa n speeds. Engine No. 1 a l s o e x h i b i t s t h i s c h a ra c t er i s-t i c b u t t o a much lesser ex t en t than engine No. 2.

I n i t i a l l y , t h e se a c c le r a t io n d a t a w e r e t o b e used t o e s t a b l i s h t h e STOLHowever, dued l e de ten t pos i t io n which cor responded t o a fan speed of 53%.t o the p roblems d i scussed i n th e p revious se c t i on , t h e t h r o t t l e h as no f l i g h t13


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i d l e de te nt and normal STOL landing oper atio n i s a t 60% of f an speed. Becauseof t he geometry of th e overhead t h r o t t l e sys tem, th e 60% se t t in g forms a nat-u r al f l i g h t i d l e p o si t io n .E n g i n e s t ab i l i t y - S t ab i l i t y t e s t s w e r e conducted on a l l en gi ne s t o demon-

s t r a t e accep tab le i n l e t opera t ion and accep tab le su rge margins wi t h increasedf u e l co n t r o l a cce l e r a t i o n s ched ul e s. T hese tes ts w e r e conducted with a l lbleeds off and th e f u e l f low increased by 5% (TEST position for compressorsurge de te c t ion ) . To check s t a b i l i t y under s evere opera t ing cond i t ions aser ies of t r an s i e n t s , co n s i s t i n g of r ap i d acce l e r a t i o n s , d ece l e r a t i o n s , andBodies, were performed on t h e engines.and the engines opera ted su rge- f ree dur ing th i s en t i r e ser ies of tests .No adverse eng ine opera t ion w a s noted .

One f i n a l s t a b i l i t y tes t w a s conducted on th e engine i n order t o checkA wind machine w a s posi-n le t and fan opera t ion a t high ang les o f a t t ack .t ioned t o p rovide a 36 m / s ( 7 2 knot) wind a t 51' t o t h e i n l e t c e n t e r l i n ewhich w a s e st i ma t ed t o b e t h e most c r i t i c a l i n l e t i n fl o w c on d it io n . Testsw e r e run on engines Nos. 1 and 2 using the same procedures as i n t h e p re vi ou st e s t s and a l s o wi th th e eng ines a t ground idle ( low m a s s f lo w) i n a crosswind,which i s th e wors t cond i t ion fo r in l e t s epara t ion . Aga in no adverse engineopera t ion w a s detected.

BLC System PerformanceAn ev al ua ti on of t h e ground-test da ta showed t h a t th e BLC system perfor-mance w a s e s s e n t i a l l y as pr ed ic te d w it h t h e amount of n e t blowing momentumb e t t e r t ha n o r e qu al t o p re d i ct e d l e v e l s a t bo th STOL i d l e and tak eo ff power.The operat ion of th e h igh-pressure re gu la to r valve w a s s t a b l e with th e pumpingperformance of each ej e c t o r compatible with i t s system demands. The pe rf or -mance of th e a i le ro n sys tem w a s i n ex ce l len t agreement wi th ca lcu la t ed per-formance, bot h with and without t he reg ul at or valv e working ( f i g. 15). Theonly deviat ion f rom this curve occurred a t t h r u s t s e t t i n g s abo ve 70 wheresystem performance w a s s l ig h t ly h igher than th a t p red ic ted . The t e s t r e s u l t sshowed that sys tem los ses a t t h e d e s ig n p o i n t were i n good agreement wi th pre-d i c t io ns , the los s es be ing 5 .2 and 6 .5 of t h e mixing t o t a l p r e ss u r e f o r t h eleading edge and ai le ro n systems, res pec t iv ely .During the BLC system t e s t s , t h e o n l y s i g n i f i c an t problem t h a t w a sencountered w a s the i na b i l i ty o f th e pneumat ica l ly powered sec t i on of thepres su re r eg u la to r va lve t o r emain c losed during eng ine s t a r t s , l e a d i n g t o

long s t a r t t i m e s and poor eng ine acc e le ra t i on ch ar ac te r i s t i c s . Th is l ac k o fpneumatic power w a s a r e su l t of lower b leed duct press ure s than preductedwhich are be l ieved t o be caused by h igher lo s se s i n th e engine b leed po r t sand high-pressu re duct ing. Th is problem w a s solved by pla cin g a motorizedv a l v e i n ser ies with t he r eg u la to r va lve which ensures a p o s i t i v e c l os u reduri ng low-speed eng ine ope rat ion .

Addi tion al inform ation on t h e engine oper atio n and ground t e s t can befound i n re fe re nc es 14-16.

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Flight PerformanceA s a p a r t of t h e management approach discus sed ear l ie r i n t h i s p ap er,r i g i d performance requirements were not imposed on Boeing, t h e a i r p l a n e p ri meco nt ra ct or . However, ambitious performance go al s w e r e es t ab l i s h ed a t t h es t a r t of t h e p r o j ec t and cu r r en t p r ed i c t i o n s i n d i ca t e t h a t most o f t h e s e w i l lb e m e t o r exceeded. The reason f o r th e high-performance levels i s t o p r ov i det h e QSRA wi th t h e maximum amount of re se ar ch ca pa bi li ty .r o l l acce le ra t i on , approach capa bi l i t y , and low community no is e are technologyt a r g e ts t h a t w e r e emp has ized by NASA and t h a t were of primary importance i nt h e development of t h e QSRA design.c a p a b i l i t i e s of t h e QSRA are summarized i n ta b l e 4.

P r o p u l s i v e - l i f t ,

Some of th e more s i g n i f i c a n t performance

L i f t capabili ty-One of t h e primary performance go al s , a minimum usablea ppro ach l i f t c o e f f i c i e n t (CL) of 4.6, i s expecte d t o be exceeded by about 16%a f t e r a llowance has been made fo r commercial f l i g h t sa fe ty margins . F igure 21compares th e l i f t performance of t he QSRA t o t h a t of a standard medium commer-c i a l j e t t r a n s p o r t ( th e B-727) and t o th e Boeing Advanced Mi li ta ry STOL Trans-port (YC-14).p ro pu l s iv e- l i f t and lead ing edge BLC, as discussed previous ly . This four-engine conf igurat ion permits a l a r g e r s p an USB f l a p and reduces adve rse yawand r o l l moments with one engine in op er at iv e, th us yi el di ng t h e improvementi n l i f t over t he twin-engine YC-14.QSRA performance i s n e a re r t o p r e d i c t io n a t th e higher ang les of a t t a c k t h a nt o th e wind- tunnel da ta . The reasons fo r t h i s are complex, but are be l ievedt o be due t o t h e f a c t t h a t t h e QSRA USB performance con f ig ura t io n has notbeen tr u l y optimized ye t and performance i s expected t o improve as more i sknown about the flow over the USB po r t io n of th e wing.

The h i g h - l i f t c a p a b i l i t y f o r t h e QSRA was achieved by applying

The a c t u a l f l i g h t d a t a i n d i c a t e t h a t t h e

Another performance area which i s v i t a l t o t h e QSRA research miss ion i st h e r o l l co n t r o l r e sp o ns i ven es s of t h e a i r p l a n e . The QSRA r o l l a c c el e ra t io ni s compared t o t h a t o f s ev e r a l o t h e r a i r p l an es i n f i g u r e 22 . This h igh (ZSRAr o l l c o n t r o l e f f e c ti v e n e s s i s achieved by i nco rpo rat ing blown ai le ro ns , mini-mizing r o l l in e r t i a , minimizing engine-out ro l l in g moment, and by th e assymet-r i c use of t he doub le - s lo t ted f l ap s fo r t r i m . This ro l l -c on tro l power i simportant because much of t h e r e s ea r ch f l y i n g w i l l be done with one of t h eoutboard ( c r i t i c a l ) engines shut down under unfavorable condi t ions i n ordert o develop c r i t e r i a f o r fu t u r e STOL a i r c ra f t .f i e d i n f l i g h t a t t h i s t i m e but w i l l be explored dur ing th e next phase off l i g h t t e s t i n g a t Ames.

This curve has not been ve r i -

STOL op er at in g envelope-The STOL op er at in g en ve lop e of t h e QSRA with a l lengines operat ing i s shown i n f i gu re 23 and th e enve lope wi th th e c r i t i c a leng ine ( e i th er ou tboard engine) inope ra t ive i s shown i n f i gu re 24. Thesef ig ure s show the ae rodynamic c ap ab i l i ty o f th e a i rp lan e . P i t c h c o n t r o l l i m i -t a t i o n s o f t h e p r es en t co n f i g u r a t i o n p r ev ent o p e r a t i o n a t f u l l USB f la p def lec -t i o n , a t 100% th ru st , and a t low speeds. S imi l a r ly , d i r e c t io na l con t ro l con-s i d e r a t i o n s l i m i t t h e minimum speed with an engine ou t i n a go-around config-u ra t i on . However, f u t u r e modi f ica t ions to the QSRA empennage, which arepre sen t ly under cons idera t ion , w i l l make it p o s s i b l e t o e x pl o re a l l cornersof t he envelope. The ex i s t in g conf i gura t ion can sa fe ly opera te a t a liftco ef f ic ie n t o f 5 .5 whi l e main ta in ing speed , angl e of a tt ac k , maneuver, and15


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go-around climb margin s.s i tu a t io n , t h e USB f l ap s are au t mo a t ic a l ly r e t r ac t ed t o t h e go-around s e t t i n g .A s shown i n f i gu re 24, t h i s p er mi ts a climb an gl e of +2O (equ ival ent t o a r a teof climb of 1.22 m / s (240 f t /min)) a t an app ro ach l i f t co e f f i c i en t of 5 .5 w i t ht h e c r i t i c a l eng ine inopera t ive .climb ang le in cr ea se s t o over +6O.

When the th r u st i s inc reased t o 100% i n a go-around

A s th e speed i s a ll ow ed t o i n c r ea s e , t h e

Th ese o p e r a t i n g e nv el op es h ave b ee n p a r t i a l l y v e r i f i e d i n t h e i n i t i a lBoe ing f l igh t t e s t and a l s o i n t h e Ames f l i g h t t e s t . Values of a i rp la ne dragare s l ig h t ly h igher than t hose p red i c ted and per fo rmance a t t h e v er y h i gh f l a ps e t t i n g s (over 63') in d i ca te s th a t the re i s some f low sep ara t io n and s l ig h t l ylower tur nin g angles than w e r e a t ta in ed i n wind-tunne l tes ts . However, asdiscussed e a r l i e r , i t i s bel ieved t ha t conf igurat ion opt imizat ion and a b e t t e runders tanding of pr op ul s iv e- l i f t aerodynamics w i l l a l l ow t h e a i r p l a n e t o even-tua l ly exceed per fo rmance p red ic t ions a t th e h ig hes t STOL f l a p se t t in gs . Thisf lo w f i e l d h a s been ex p lo r ed t o a minor e x t e n t ( t u f t s ) du ri ng t h e f i r s t ser iesof Ames t e s t s and w i l l be explo red i n g rea t dep th i n the nex t phase o f theAmes f l igh t r esearch p rogram.Approach angle-A sh or t - f ie ld a i r p l an e re qu ire s a s t eep de s cen t c ap ab i l i t y(h igh approach ang le) i n o rder t o minimize t he r equ i red a i r sp ace i n the t e r m i -n a l area , as w e l l as t o minimize community no ise ef f e c t s . The USB nozzle and

f l a p s of t h e QSRA have been des igned t o provide exce pt i ona l ly h igh f low turn-i n g of t h e e ng in e ex ha us t, y i e l d i n g h ig h l i f t approach l i f t c o e f f i c i e n t s(> 5 .5 ) w hich en ab le t h i s a i r c r a f t t o a ch i ev e v er y s t e ep app ro aches w i t h f u l lsa fe ty margins . F igure 25 gi ve s a comparison of the QSRA STOL c a p a b i li t ie sand th e descent angl e and ground r o l l of a c on ve nt io na l t r a n s p o r t a i r c r a f tlanding. A t t h e same d i s t a n c e from t h e a i r p o r t , t h e QSRA i s more than t w i c eas high as t h e co nv ent io n al a i r l i n e r and i t i s able to s top on the runwaybef ore toda y 's commercial t ra ns po r ts complete t h e i r f l a r e and touch down ont h e runway. The land ing and take off performance of t h e QSRA h as b een v e r i f i edduring t h e i n i t i a l f l i g h t t e s t with ground r o l l d is t an ce of 202.4 m (664 f t )dur ing a maximum performance takeoff and of less than 167.6 m (550 f t ) dur inga STOL landing.

Because no ise a t t e nu a t es r ap id l y wi th d i s t anc e , th e h igher approach a l t i -tude of t he QSRA i s a big fac to r i n reduc ing community no i se e f f ec t s ; t h i she igh t can be in cre ase d even more by landin g toward t h e ce nt er of t h e runway.Another tech nique t h a t may reduce community nois e ef fe c t s , by keeping t h en o i s e comple te ly wi th in th e a i rp or t boundaries dur ing ta keo f f , i s a s p i r a l o rc i r c l in g approach and depar ture . S imulat ion s t ud ie s have shown th a t th e QSRAno is e can be conf ined t o t h e boundar ies of a t y p i c a l g e ne r a l a v i a t i o n a i r p o r t ,a n d f l i g h t t e s t has shown that the QSRA i s capable of a 337.1-m (1106 f t )r ad i u s d e p a r t u r e w i t h a 30 b ank an g l e w i t h an i n c r ea s e i n a l t i t u d e o f 884 m(2900 f t ) a f t e r a f u l l 360 t u r n .

Acoustic PerformanceOne of t he primary goa ls of t h e QSRA program w a s t o h av e a 90-EPNdBcommunity noise impact area of no more than 2.5 km2 (1 m i l e2 ) f o r a 668,182-M(150,000 lb) commercial a i rp la ne based on QSRA technology. Figure 26 shows

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how t h i s go al compares wit h t h e noise-impact area of a cu rr e nt medium sho rt-h a u l commercial t r a n sp o r t (B-737, DC-9).were measured dur ing t h e f i n a l phase of t he Boeing f l ig ht - t es t program, ext ra-po lat ed , and compared t o th e program goa ls. The maximum e f fe c t i v e perc eive dn o i s e l eve l (EPNL) measured on t h e 152.4-m (500 f t ) s i d e l i n e d u r in g t akeo ffw a s 93.5 EPNdB and t h e go a l w a s 92 EPNdB; during landing i t w a s 89 EPNdB andt h e g o a l w a s 90 EPNdB. As can be seen , th e va lues are s l i g h t l y h i gh e r d u ri n gtakeoff and s l ig h t ly lower dur ing landing. ( I t shou ld be no ted th a t thesetakeoff and landing no is e l eve ls are based on a 152.4-m (500 f t ) s id e l i n e andhence th e t akeof f n o i s e i s sub s t an t i a l ly g re a t e r than t ha t which would bemeasured i n accordance with FAR 36 .) Seve ra l major d i f f e r enc es ex i s t betweent h e QSRA and any p o t e n t i a l t r an s p o r t a i r c r a f t ba sed on t h e QSRA technology, .with t he most impor tan t o f the se be ing th e h igh d rag conf igur a t ion of th e QSRAdur ing takeof f , d ue t o t h e ab sence of f a i r i n g s and r e t r a c t ab l e l an d in g g ea r,and t h e f a c t t h a t t h e QSRA h as n o n r e t r ac t ab l e v o r t ex g en e r a t o r s and n o zz l edoors i n th e takeoff and c r u i se conf igura t ion . The c lea n t r a nsp or t conf igura-t i o n would r e s u l t i n a takeoff /c l imbout speed inc re as e from th e 90 knot QSRAs peed t o ab ou t 130 k n o t s, r e s u l t i n g i n a d e cr e as e i n t h e ta ke of f s i d e l i n eno is e l e v e l t o approximately 91.5 EPNdB. Based on t h i s clean confi gura tionQSRA, a 668,182-N (150,000 l b ) commercial tr a n s p o r t would have a 90 EPNdBnoise impact area of 7.03 km2 (2.8 mi le2 ) compared t o th e QSRA goa l of 2.51km2 (1 mi le2) . T hese n o i s e ex t r ap o l a t i o n s are pre l iminary re su l t s based on al im i ted da ta base and are bel ieved t o be co n si d er abl y l a r g e r t h an t h e n o i s eareas t h a t w i l l be achievable by a commercial t r a nsp or t based on the QSRAtechnology. Thi s be l i ef i s based on a number of fa ct or s , d iscussed i n th ef o ll o wi n g s ec t i o n s , t h a t c an b e e li m i n at ed i n any f u t u r e t r an s p o r t i f t hey arei s o l a t e d as s i g n i f i c an t n o i s e so u rce s ( e .g . , n o n r e t r ac t i n g v o r t ex g en e r a t o r s ) .

The ac t u a l n o i s e l eve ls of the QSRA

Data analysis-The data w e r e analyz ed by th e systems and methods used i nFAR-36 no i se ce r t i f i c a t io ns , w i th 1 /3 oc t i ve band s pe c t ra in teg ra t ed over 0.5-sec per iods a t increments of 0.5 sec. Computer pro cessing mated a co us ti c da taw i th t h e a i r p l a n e p o s i t i o n as d ete rm in ed o p t i c a l l y and w it h t h e f l i g h t p r o f i l ed a t a , s y n t h e s iz i n g fl y o v e r n o i s e t i m e h i s t o r i e s f o r t h e v a ri o u s re f e re n c ef l i g h t p r o f i le s .

Far f i e l d results-The community no is e le v e l d at a r e s u l t from measurementsmade with a pre c i s ion of abou t 21 EPNdB i n t h e EPNL measurements and ab ou t +2PNdB i n PNL measurements.with th e USB f laps . re t r ac te d than the y were with a 3 f l a p s e t t i n g and t h es i d e l i n e n o i se l e v e l s w e r e r e l a t i v e l y u n af f ect ed by f l ap co n f ig u r a ti o n .though air f r ame noi se w a s present i n some measurements, i t d i d n ot s i g n i f i -c a n t l y i n f l u e n c e t h e PNL and EPNL n o i se l e v e l s.p r e d i c t io n s , w i th t h e h ig h er l e v e l s a p pe ar in g t o b e r e l a t e d t o a random aero-dynamic no is e genera ted by in te ra c t io n of tu rbu lence wi th in t he j e t f low wi tht h e wing t r a i l i n g edge .may be the vor tex genera to r s .component seems t o be t h e r e s u l t of e ng in e i n s t a l l a t i o n e f f e c t s .

The n o i s e l ev e l s a lo n g t h e f l i g h t p a t h are higherA l -

The measured noise exceeded

I t i s b e l iev ed t h a t o ne p o s s i b l e s ou r ce of t h i s n o i s eI n a d d i t i o n , a large, low-frequency (200Hz)

An ad di t i on al anomaly appeared i n some of t he d at a f o r re t r ac te d USB f l a pt h a t w a s taken a t a d i f f e r e n t t i m e t h an t h e rest of th e dat a . The l eve ls oft h i s d a t a p o i nt appeared t o b e e s s e n t i a l l y t h e same as th e 30 f l ap da ta .T h i s lo wer f a r - f i e l d n o i s e l ev e l w a s corroborat ed by nea r-fie ld measurements17


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di scussed i n t he next sect i on.anomal y at t hi s t i me but subsequent t est i ng of t he QSRA wi l l i nvest i gat e t hi seffect.There i s no reasonabl e expl anat i on of t hi s

Near - f i el d measurement s- Near - f i el d noi se measur ement s were made wi t hei ght m cr ophones f l ush- mount ed on t he f usel age ext eri or surf ace and f ourl ocat ed i nsi de t he ai r cr af t . These measurement s showed t hat noi se l evel s i n-creased uni f or m y wi t h engi ne power l evel s, appr oxi mat i ng a 40 l og V jt i onshi p, wi t h maxi mum ext er i or noi se l evel s of about 150 dB. The i nt er i ornoi se l evel s wi t h i nboar d engi nes shut down wer e about 10 dB l ess t han wi t hal l engi nes oper at i ng, especi al l y i n l ocat i ons where f l ow at t achment and f use-l age scrubbi ng occur r ed. The maxi mum measur ed i nt er i or noi se l evel s wer e 118dB i n t he af t cabi n at hi gh power set t i ngs. I t shoul d be not ed t hat t he f use-l age i nt er i or i s unt r eat ed and i s not r epr esent at i ve of t he noi se l evel s thatwoul d exi st i n a si m l ar commer ci al t r ansport ai r craf t .

rel a-

Dat a si gni f i cance- The acoust i c dat a pr esent ed i n t hi s sect i on ar e pr e-l i m nar y and do not r epr esent a compl ete anal ysi s or a good dat a base. Rat her ,t hey r epr esent a st art i ng poi nt f r omwhi ch t o bui l d a mor e compl et e underst and-i ng of pr opul si ve- l i f t ai r craf t noi se, and to devel op t he r equi r ed f l i ght ex-per i ment s t hat wi l l pr ovi de a t echnol ogy base f or f ut ur e t r ansport s based onQSRA pr ogr am goal s. As has occur r ed i n several ot her ar eas, t he QSRA acoust i cconf i gur at i on has not been opt i m zed. Opt i m zati on of t he conf i gur at i on canbe expect ed t o r educe t he noi se l evel s f r om t hose measured i n t hese t est s. I tshoul d be not ed t hat a r educt i on i n measur ed noi se l evel of onl y 2 dB wi l lr esul t i n noi se i mpact ar ea r educt i on of appr oxi mat el y 60% Addi t i onal dat aon the QSRA f l i ght t est s and acoust i c t est s are gi ven i n r ef er ence 17.

FUTURE PLANS AND EXPERI MENTS

I ni t i al Test s and Conf i gur at i on Opt i m zat i onThe i ni t i al NASA f l i ght pr ogr am at Ames Resear ch Cent er wi l l l ast forappr oxi matel y 1 year s and wi l l be devoted to envel ope document at i on wi t h con-f i gur at i on opt i m zat i on as requi r ed. As di scussed i n sever al previ ous sec-t i ons, smal l changes i n t he conf i gur at i on or f l ow f i el d can have a si gni f i cantef f ect on propul si ve- l i f t ai r craf t perf ormance. Dur i ng t hese i ni t i al t est s,a ser i es of experi ment s wi l l be per f or med to def i ne t he f l ow f i el d and theef f ect of t hi s f l ow f i el d on t he QSRA power ed- l i f t per f or mance. For exampl e,a number of exper i ment s wi l l be perf ormed t o determ ne t he ef f ect of vor t exgener at or si ze and l ocat i on on t he QSRA aerodynamc perf or mance and f ar - f i el dacoust i cs. Aerodynam c per f ormance wi l l be document ed and compared t o a r ef -er ence basel i ne as pr ovi ded by a r el at i vel y sophi st i cated mathemat i cal modelof t he QSRA and by t he use of f l ow- vi sual i zat i on t echni ques such as tuf t s.The acoust i c measur ement s wi l l be cr oss cor r el at ed wi t h near - f i el d measurement s 'i n or der t o i sol at e and i dent i f y the sour ces of t he noi se, and t hese exper i -ment s wi l l be augment ed wi t h smal l scal e t est s as r equi r ed.al t er nat i ve f l i ght pr of i l es wi l l be eval uat ed i n or der t o f ur t her r educe communi t y noi se i mpact ar eas.

I n addi t i on,

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One i nt er est i ng modi f i cat i on under consi der at i on i s t he repl acement oft he pr esent bl own l eadi ng edge wi t h an unbl own l eadi ng edge sl at . W nd- t unnelt est s descr i bed ear l i er showed t hat an unbl own l eadi ng edge woul d degr ade per -f ormance by r educi ng t he angl e- of - at t ack margi n 4' t o 5O (ref. 18) . I f thi scan be ver i f i ed i n f l i ght , f ut ur e desi gner s of hi gh- per f or mance STOL ai r cr af twi l l have a f i r m t echni cal base f or t he sel ect i on of bl own ver sus unbl own l ead-i ng edges.Another modi f i cat i on pl anned f or t he QSRA i s t o i ncr ease t he gr oss wei ghtt o 267,273 N (60,000 lb).l b/ f t 2) and gi ve t he QSRA t he capabi l i t y of oper at i ng over a r ange of w ngl oadi ngs f r om 3117 t o 4795 N/ m2 (65 t o 100 l b/ f t2) t o i ncr ease i t s resear chversat i l i t y.

Thi s wi l l pr ovi de a wi ng l oadi ng of 4795 N/ m2 (100'

Fl i ght Exper i ment sAf t er t he i ni t i al NASA f l i ght r esear ch pr ogr am and conf i gur at i on opt i m -zat i on, t he QSRA wi l l be made avai l abl e f or t he f l i ght - exper i ment s pr ogr am

I n t he i ni t i al sect i ons of t hi s paper, t he concept of a resear ch ai r cr af t bei nga f aci l i t y f or f l i ght r esear ch was di scussed. When t he QSRA ent ers t he f l i ght -exper i ment s phase i t wi l l f ul f i l l t hi s goal and become a nat i onal f aci l i t y f orf l i ght r esear ch.f l i ght exper i ment s. Some of t he experi ment s wi l l be accompl i shed as i n- housee f fo r ts ; ot her s wi l l be done j oi nt l y w t h ot her gover nment agenci es, f or exampl e, t he devel opment of cer t i f i cat i on cri t er i a f or f ut ur e STOL ai rcraft . I not her cases, t he wor k wi l l be cont r act ed, par t i cul ar l y when t he exper i ment i n-vol ves st r uct ur al modi f i cat i on t o t he ai r pl ane or t he devel opment and i nst al -l at i on of new equi pment . The QSRA i s , however , a nat i onal f l i ght f aci l i ty .As such, i t i s avai l abl e t o the aer onaut i cal communi t y i n t he same way t hat aNASA w nd t unnel or si mul at or i s avai l abl e.

Research per sonnel wi t hi n NASA ar e pl anni ng a pr ogr am of

QSRA wor kshop- On November 29 and 30, 1978 a wor kshop wi l l be hel d atAmes Research Cent er i n order t o pr ovi de i ndust r y, uni ver si t i es, and gover n-ment agenci es wi t h i nf or mat i on on the capabi l i t i es of t he QSRA and to provi dea mechani sm by whi ch par t i ci pat i on i n t he f l i ght exper i ment s pr ogr am can bei mpl ement ed. I t i s hoped t hat t hi s pr ocedur e wi l l l ead to br oad par t i ci pat i onby t he aer onaut i cal communi t y i n t he QSRA f l i ght r esear ch pr ogr amAl t hough t he f l i ght - exper i ment s phase wi l l not of f i ci al l y begi n f orsever al years , i t i s bel i eved t hat many exper i ment s, par t i cul ar l y, sel f -cont ai ned exper i ment s, can be f l own on t he QSRA dur i ng the i ni t i al f l i ghttests. I n addi t i on, some exper i ment s, such as acoust i c measurement s and cor -r el at i on of smal l - scal e t est i ng wi t h the QSRA, can and shoul d be done concur -r ent l y wi t h the earl y f l i ght pr ogramexperi ment s whi ch i s under consi derat i on i nvol ves t he use of Ames' qui et noi semeasur i ng ai r pl ane, t he YO-3A, t o make f r ee- f i el d acoust i c measurement s of t he

QSRA f l ap and i nl et noi se. A number of other experi ment s ar e pl anned i n var i -ous r esear ch ar eas such as avi oni cs, comput er cont r ol s yst ems, i nl et f l owf i el ds, acoust i cs, st r uct ur al vi br at i on, and aer odynam c per f or mance.

For exampl e, one seri es of acoust i c

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Fl i ght demonst r at i on- Anot her act i vi t y i n t he ear l y pl anni ng st ages i sdemonst r at i on f l i ght s at ai r por t s i n t he San Franci sco Bay Ar ea f or pot ent i alusers of t he t echnol ogy.t echni cal per sonnel f r om i nt er est ed ai r craf t manuf actur er s.car r y passengers because i t i s qual i f i ed onl y f or a crew of t wo r esear chpi l ot s. However, f l i ght demonst r at i ons wi l l expose pot ent i al user s of t hi st echnol ogy to the shor t - f i el d capabi l i t y, t he maneuver abi l i t y, and the l owcommuni t y noi se l evel s of whi ch t he QSRA i s capabl e. Lat e i n t he i ni t i alf l i ght pr ogr am i t i s al so pl anned that qual i f i ed pi l ot s f r om ot her organi za-t i ons wi l l be i nvi t ed t o f l y and eval uat e the QSRA wi t h a NASA r esear ch pi l otas an i nstruct or- pi l ot . ' 'Fl ap STOL Research Ai r pl ane and wi l l be r epeat ed wi t h t he QSRA.

Thi s woul d i ncl ude ai r l i ne and ai r por t of f i ci al s andThe QSRA wi l l not

Thi s was done successf ul l y wi t h t he Augment ed J et

REFERENCES1. Qui gl ey, Her vey C. ; I nni s, Rober t C. ; and Gr ossm t h, Set h: A Fl i ght I n-vest i gat i on of t he STOL Charact eri st i cs of an Augment ed J et Fl ap STOL

Resear ch Ai r cr af t . NASA TM X- 62334, 1974.2. Qui et Pr opul si ve Li f t Resear ch Ai r cr af t Desi gn St udy. NASA CR- 137557,1974.3. Qui et Shor t Haul Resear ch Ai r cr af t Desi gn St udy. NASA CR- 137554, 1974.4. Cochr ane, J ohn A. ; and Car r os, Rober t J . : Hybr i d Upper Sur f ace Blobm Fl apPr opul si ve- Li f t Concept f or t he Qui et Shor t - Haul Resear ch Ai r craf t . AI AAPaper 75- 1220, Oct . 1975.5. Cochr ane, J ohn A. ; and Boi ssevai n, Al f r ed G : Qui et Shor t - Haul Resear chAi r craf t - Cur r ent St atus and Fut ure Pl ans. AI AA Paper 78- 1468, Aug.

1978.6. Shovl i n, M chael D : Ef f ects of I nl et Ai r f r ame I nt egr at i on on t he I nl etof a USB Four Engi ne STOL Ai r pl ane. AI AA Paper 78- 959, J ul y 1978.7. Ni ckson, Theodor e B: Large Scal e W nd Tunnel I nvest i gat i on of t he Qui etShor t - Haul Research Ai r cr af t ( QSRA) Conf i gur at i on. NASA CR- 152095, 1978.8 . Gunnar son, Dani el W; and McArdl e, J ack C : Devel opment and Test of anI nl et and Duct t o Pr ovi de Ai r f l ow f or a W ng Boundar y Layer Cont r olSystem AI AA Paper 78- 141, J an. 1978.9. Reshot ko, Meyer ; Kar chmer , Al l en N. ; Penko, Paul F. ; and McAr dl e, J ack G:Core Noi se Measur ement s on a YF- 102 Turbof an Engi ne.J an. 1977. AI AA Paper 77- 21,10. M ddl eton, Robi e; and Vi ncent , J ames H: Qui et Shor t - Haul Resear ch Ai r -craf t Phase I1 Fl i ght Si mul at i on Mat h Model - Fi nal Repor t .152197, 1978. NASA CR-

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11. Wilcox, Darrell E.; and Quigley, Hervey C.: V/STOL A i r c r a f t Simulation -Requirements and Capabi l i t ies a t Ames Research Center.78-1515, Aug. 1978. AIAA Paper

12. Riddle, Dennis W.: A Pi l o t ed S imula tor Analys is o f t he Carrier LandingC ap ab i l i t y of t h e Qu ie t Short-Haul Res ear ch A i r c r a f t . NASA TM-58508,1978.

13. Stevens, Fred: Configura tion De fi ni t i on Document of th e QSRA. (ProposedNASA hi gh number co n tr a c to r re p o r t . )14. M c N e i l l John M.: QSRA/YF-102 Engine Per form ance and Co nt ro l. BoeingDocument D340-10206, Boeing Commercial A ir pl an e Company, S e a t t l e , Wash-ington, 1978.15. McNeill, John M.; and Harkonen, Dennis L. : QSRA Ground T e s t Report VolumeI-Propulsion and Fuel System Tes tin g.Boeing Commercial Ai rp la ne Company, S e a t t l e , Washington, 1978.Boeing Document 0340-13701-1,

16. Shah, Ani1 D.: QSRA Ground T e s t Report Volume II-Systems. Eoeing Docu-ment D340-13701-2, Boeing Commercial A ir pl an e Company, S e a t t l e , Washing-ton, 1978.17. Analys i s o f Con t rac to r ' s Tax i and F l igh t T e s t of t h e QSRA. (Pro pose d NASAhigh number contractor repor t . )18. Holtman, Donald N . ; and Howard, Wes M.: Large Sca le Wind Tunnel In ve st i-ga t i on fo r Future Modif icat ions t o th e Quiet Short-Haul Research A i r -c r a f t (QSRA) Co nf ig ur at io n. (Proposed NASA hig h number c o n t r ac t o rr e p o r t . )

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TABLE 1. - QSRA I NI TI AL GOALS AND REQUI REMENTS( PARTI AL LI ST)Requi r ement s

00

0

0

0

Goal s0

0

0

0

e0

0

Day, VFR operat i on onl yCr ew of t wo resear ch pi l ot sModi f i cat i on of GFE C- 8A Buf f al oUse of f our GFE YF- 102 engi nesHybr i d upper surf ace bl ow ng pr opul si ve l i f t concept

Approach l i f t coef f i ci ent - 4.6 ( st eep appr oach wi t h margi ns)Appr oach pat h of -7.5' wi t h mar gi n f or gust s, wi nd, et c.90 EPNdB combi ned t akeof f and l andi ng f oot pr i nt ar ea, when scal ed t o668, 182 N (150, 000 l b) of 2. 5 km2 (1 ml e2)M ni mum dur at i on of t est m ssi on- 50 m nM ni mum w ng l oadi ng at gr oss wei ght = 3117 N/ m2 65 l b/ f t2)Maxi mum cr ui se speed 160 knot sW ng/ nacel l e conf i gur at i on r epr esent at i ve of cr ui se at M = 0. 74.

2 2


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TABLE 2. -QSRA FUNDING D I S TRI BU TI O N

Prel iminary des ign s t ud ie s 2 ,000,000Wind t un ne l and eng ine t e s t s 1,000,000Engine program 2,000,000A i rp l ane d e t a i l d e s i g n and f ab r i ca t i o n 22,000,000Proof-of-concept f l ight t e s t 2,000,000Tota l funding av ai la bl e $29,000,000

TABLE 3.-BLC FLOW DISTRIBUTION

Engine pos i t io n123

BLC segmentR i g h t a i l e r o nRight leading edgeLef t l ead ing edgeL e f t a i l e r o n

TABLE 4. QSRA PREDICTED PERFORMANCE

Approach l i f t c o e f f i c i e n t ( s t e e p approach with margins) 5.5Approach path with margin fo r wind, gu st s , etc. -7.5Duration of STOL t e s t mis sio n 102 minL an d i n g f i e l d - l en g t h a t 213,370 N (48,000 lb)(W/S = 3836 N/m2 ( 8 0 l b / f t 2 ) )

(1.67 fa ct or over 10.7-m (35 f t ) obs ta cl e)

426.7 m (1400 f t )

Takeoff f i e l d l eng th a t 668,182 N (150,000 l b ) 403.9 m (1325 f t )(10.7-m (35 f t ) obs t ac le wi th c r i t i c a l enginei n o p e r a t i v e ( C E I ) a t decis ion speed)

Turn radius a t 30 bank an gl e 213.4 m (700 f t )

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Figure 1 . - The Quiet Short-Haul Research Airplane (QSRA) Performing a S N Xapp ro ach p r io r to landing a t Ames Research Center .

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Figure 2.-The 0.55-scale QSRA model mounted in the Ames 40- by 80-FootWind Tunnel.

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Fi gu re 3.- Th e YF-102 (QSRA) e ng in e i n s t a l l e d i n t he L e w i s Ver t ica l Lif t FanF a c i l i t y i n p re p a ra t i on f o r c o nf l ue n t f lo w b a s e l i n e t e s t i n g .

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Figure 4 . - P i l o t ' s v i e w from t h e cab of t h e Ames FSAA dur ing the QSRAf l i g h t s im u la t io n .

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TOGW. Ib 5o.m 222260NWING AREA, f tz 6 ~ 65.74m2WING LOADING, bIh2 83 3987.4Nlm2ASPECT RATIO 9THRUSTlWEIGHT .HI

/ 73.5h A22.40 m

93.25 R28.42 m

Figure 5. -The QSRA a i r p l a n e layout.

Figure 6 . -The QSRA wing and fusel age under co ns tru ct ion a t the BoeingDevelopmental Center i n S e a t t l e , Washington.

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1. FAN STAGE2.FAN STATOR3. REDUCTION GEAR ASSEMBLY6. USTOMER B LEED PORTS7.COMBUSTOR8. GAS PRODUCER TURBINES

4. ORE A XI A L COMPRESSOR5. CORE CEN TRIFU GA L COMPRESSOR 9. POWER TURBINES10. ACCESSORY GEARBOX11. SUPERCHARGERFigure 7 . - A cutaway view of t h e YF-102 (QSRA) engine which w a sb u i l t by AVCO-Lycoming D ivis io n.

T18.56in.0.471mIMA X. THRUST 7500 b 33409.1NWEIGHT DRY 1215 b 551.1 kg

N, 7600 FAN)N, 19660SFC 0.41MGT 1665F907 C

(POWER TURBINE 17600

TOTAL AIRFLOW 267 b/sec 121.1 kg/secCORE AIRFLOW 37 blsec 16.8kg/secB.P.R. 6.2

Figure 8. -YF-102 QSRA) engine layout .9


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I I 6' INBD4.6 OUTBD

134.30 in.3.411 rn4

Figure 9.-The QSRA nacel le layout.

STRUCTURAL COWLAN D NO ZZLE ASSYACCESS DOOR TOFWD ACCESSORIES STRUCTURAL

FA N DUCT RAMP

LOWER FA N DUCTREMOVABLE \ INBOARD, OUTBOARD

A ND UPPERSUPPORT

/ F=OWER COWL DOORCOWL WING FAIRINGINBOARD, OUTBOARD

Figure l O . - V i e w of the QSRA na ce ll e main str uct ura l elements.

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ORIGINAL PAGE DOF POOR QUALITYNOSE COWL PRIMA RY

NOZZL E

COOLING

ACCESSORY DR IVESYSTEMMAN1FOL D

Figure 11 .- Th e engine bu ild up showing th e YF-102 (QSRA) eng ine ins ta l l ed inan assembly con sis tin g of the engine, core cowl, inlet, and primary nozzle.

EXHAUST MIXING

---------7 PNdB INLE T NOISEATTENUATIONDOUBL E L AYER L INING WING SHIELDING

12 PNd B AFT FA NATTENUATIONINNER A ND OUTERFAN DUCT WAL L S

SINGL E L AYER L INING

Figure 12.-Location of the acoust ic l ining panels in the QSRA i n l e tand a f t fan f l o w passages.

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HIGH-PRESSURE

Figure 13. -The layout of t h e QSRA boundary-layer control (BLC) system.systems i n th e event of an en g i n e f a i l u r e .The two phantom li n e duct s only connect th e lead ing and t r a i l i n g edge

BLC EJECTOR FIRE BOTTLESDRAIN MAST

STARTERHY D PUMPCDS GENCDS COOLER AND FA NCDS ACCUMULATORCDS FILTER

Figure 14 .-Sys tems layou t i n the QSRA nace l le .

3


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ORIGINAL PAGB 18OF POOR QUA1,ITY

z 1600mU

1200Ic1f 800-m

400-

oOOr

- Et2mI--a

.5zmz

-v

I

st;

0 -MA X. ENGINE THRUST*

4 0 0 ~00

NOZZL E

AIR SUPPLY TOBLC SYSTEMt t HIGH - PRESSUREAIR IN

Figure 15. -Th e performance of t h e QSRA a i l e r o n BLC system shown as a f u n c t i o neng ine th rus t . The BLC ej ec to r which combines t h e fa n and core a i r f rom theengine t o prov ide th e BLC system a i r flow i s shown i n t h e i n s e r t .

EL EVATOR

(DOUBLE SLOTTED)SPO IL ERS

RUDDER(DOUBLE HINGE)USB FLA PS

&FL AP (DOUBLE SLOTTED)AIL ERON

Figure 16. -Loca t ion o f the QSRA main f l i g h t c o n t r o l s .

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100 120Eeg 100z 80 8sW 70 60WK0 60 40I-K

ESTRICTED ZONE3 50 20s 40 020 30 40 50 60 70 80 90 100

32,000

ZI-- 28 000vKIII2Pazt 24,000

20.000

cCf8I--v3aE

-

-

-

-

CORRECTED FAN SPEED, N p / a , % rpm

PIv

IcI

6000-

2Gz2 500

5000

Figure 17. -The re la t i on sh ip of th e fan and core compressor speeds wit h eacho ther and wi th eng ine th rus t l eve l for the YF-102 (QSRA) engine.

-

SEA L EVEL STATIC3%FAN BL EED30HPX

OUTBOARD ENGINEINBOARD ENGINE

HIGH SHAFT7 0 0 0 r / T R Q U E L IM IT

-----

6500E==== +.\E D

4500 20 40 60 80 100 120AM BIENT TEMPERATURE, TAM, OFI I I I-20 -10 0 10 20 30 40 50C

Figure 18.- The e f f e c t of ambient temp erat ure on t h e YF-102 (QSRA) engineth ru s t . The engine i s torque- l imited a t t h e lower temperatures and environ-ment co nt ro l system (ECS) bleed i s only taken f rom t h e inboard engines .34


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YF-102 FAN 0 ENG. 1 (YFO1)BYPASS MAP A ENG-2 (YF02)

N E3 ENG-3 (YF03)0 ENG.4(YF05)oo%-$= 7600rpm

RELATIVE NOZZLE AREA1.45

p 1-402 .35a 1 . 3 0 ~ CCEPTANCE-9 PROGRAM* TESTS DURINGa

UPPER LIMIT FOR ENGINE

1.25.20 ROTATING STALL LINE,

E 1.15z 1.10

.051 I40

FROM UNTRIMMED NOZZLESURGE LINE,

ESTIMAT

NASA Quiet Haul Aircraft

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