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NASA Technical Memorandum 79124

W I N D T U N N E L P E R FO R M A NC E O FFOUR ENERGY EFFICIENT PROPELLERSDESI G NED FOR M A C H 0 8 C R U I S E

by Robert J Jeracki Daniel C Mikkelson,and Bernard J BlahaLewis Researc h CenterCleveland, Ohio

TECHNICAL PAPER to be presented a t theBusiness Aircraft Meetingsponsored by the Society of Automotive Engin eersWichita, K a n s a s , April 3-6, 1979

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TH E ISCREASED E ?PWSI S c n f u e l c o n s e r v a t i on hass t i n u l a t e d a r en ew ed i n t e r e s t i n t u r b o pr o pp ow er ed a i r c r a f t . S t u d i e s by LASA a n d i n d u s t r yor a i r c r a f t d e s i g n e d f o r ?!ach 0 . 8 c r u i s e a bo ve9.1;: km (30 000 f t ) a l t i t u d e i n di c a t e s i g n i f i -c a n t ' c lo ck f u e l s a vi -g -; a nd d i r e c t o p e r a t i n gc c s t r e d u c t i c n s of t s r b o ? r o F p o r c e r e d a i r c r a f to v e r c o n ? a r a b l e t u r b o f a n ?o:.rsred a i r c r a f t .S p e c i f i c s t u d i e s and s u n a r i s s a r e g i ve n i n~ e f s . I)* t o ( 3 4 ) . .I r e c e n t s t a t u s r e p o rt onNASA's Advanced TurboTrc? Prcject , which i sp a r t o f i t s A i r c r a f t E ne rg y E f f i c i e n c y Pr og ra m ,i s d i s cu s s e d i n R e f. ( 2 ) . Eigh speed tu rbo-p ro p p r o p ul s i o n h a s b ee n s t u d i e d f o r a v a r i e t yof s u S so n ic a i r c r a f t a p F i i c a t i o - s , b ot h c i v i la c d m i l i t a r y . The m a gn i tu d e o f t h e f u e l s a v-i n g s cf t u r b o p r o p p ow er ed a i r c r a f t o v e r com-? a r a b l e t e c hn o l o g y t u r b o f a n po i; er ed a i r c r a f ti s g e n e r a l l y i n f lu e n ce d b y a i r c r a f t c r u i s esp eed a n d o p e r a t i n g r a n g e . This i s shov.3 i nt h e t r end c u r v e s of b l o c k f u e l s a v i n g s v e r s u so p e r a z i n g r a n g e s h o . m ir . F i g . 1 from Ref. ( 2 ) .F u e l s a v i n g s f r o m 15 tc 39': zt Xac?. 3 . 8 may ber e a l i z e d by t h e us e 0 5 a? acvanced h igh-speedtu rb op ro p. The Zlach C . 7 c r u i s e a i r c r a f t showl a r g e r f u e l s a v i n g s t h a n t h o s e d es ig ne c! f o rXach 0 . 8 s i n c e t h e a d v a n ta g e of t h e h i g h s pe e dt u r b o p r o p p r o p u l s i o n sys t e n o v e r t h e t u r b o f a nin cr ea se s a s Zlach number i s d s c r e a s e d . F u e ls a v i n g s o f o v e r 2 0 % n a y b e r e a l i z e d a t Mach 0.7f o r r a n ge s t y p i c a l of b u s i n e s s j e t a i r c r a f t .The f u e l s a vi n g s a l s c i n c r e a s e s f o r s h o r t e rs t a g e l e n g t h o p e r a t i o n b e ca u se a l a r g e r p o r t i o no f t h e b l o c k time i s s p e n t a t ch e lo wer sp eed sof c l i m b a nd d e s c e n t w h e r e r u r b o p r o p p r o p u l s i o no f f e r s ev en l a r g e r a dv a n t a ge s . T he se p r o j e c t e da i r c r a f t f u e l s a v i ng s w i t h t h e h i g h s pe ed t u r -boprop have a s i g n i f i c a n t i n pa c t on t h e a i r -c r a f t d i r e c t op e r a ti n g c o s t . S in ce f u e l c o s t sab o u t 4 0% o f t h e d i r e c t o p e r a t i n g c o s t (DOC)o f m e di um -t o -s h or t h a u l c o mm e rc i al a i r c r a f t , a2 0 t o 2 5 % f u e l s av in gs r e s u l t s i n an 8 t o 10%l o wer DOC ( 2 ) . F u e l s a v i n g s a r e g r e a t e r ( 2 2 )f o r l o n g er r an ge a i r c r a f t and s o t h e DOC sav-i n g s a r e g r s a t e r . Very l o ng r a ng e a i r c r a f t ca nt a k e a d v a nt a g e o f r e d u c e d f u e l c o ns u mp t io n t or e d u ce a i r c r a f t w e i gh t a 2d s i z e wh ic h g i v e sa d d i t i o n a l DO C r e d u c t i o n a s w e l l a s r e d u c i n ga c q u i s i t i o n c o s t a nd l ow er l i f e c y cl e c o s t .The v a r i a t i o n o f DOC s a v i ng s w i t h f u e l c o s t sf rom Ref . (16) i s shown i n Fig . 2 . The curvesa r e b a se d o n e a r l i e r s t u d i e s w i t h b ot h 1 98 5t e c h n o l og y a s s u m p t i o n s a n d a l s o 1 97 6 t e c h no l -

ogy ( 1 6 , 2 3 - 2 4 ) . Boeing and Lockheed examined1985 technology l e v e l t u r b op r o p e n g i n e s v e r s u se q u i v a l e n t t e c h n o l o g y l e v e l t u r b o f a n e n g i n e s .The B oe in g a i r c r a f t d e s i g n w a s b ased o n 1 9 7 6t e ch n o lo g y l e v e l s wh il e Lockheed used 1985t e ch n o lo g y l e v e l s . Do u g la s u sed th e DC9-30 asa basis o f compar ison and compared bo th cur -r e n t t e c h n o l og y t u r b o p r o p e n g i n e s a nd 1985t e c h n o lo g y l e v 2 1 e n g i n e s t o t h e c u r r e n t DC9-30c o n f i g u r a t i o n u s i n g l o w - b yp a s s - r a t io JT8D t u r -b o f an en g in es . A s c a n b e s e e n , a wid e sp r eadi n DOC s a v i n g s was a c h i e v e d , r e f l e c t i n g thev a r i o u s a s su m pt i o ns of p r o p e l l e r e f f i c i e n c y ,f u s e l a g e de s i g n a nd w ei g h t f o r n o i s e a t t e n -u a t i o n, a i r c r a f t c o nf i g u ra t i o n s, d e si g n s t a g el e n g t h s , m ai n te n an ce c o s t s , e t c . I n a l l cases,however , there i s a v e r y s i g n i f i c a n t im pr ov e-ment f o r t h e t u r b op r o p p ow er ed a i r c r a f t . T h i si s e s p e c i a l l y t r u e a t t h e s h o r t e r s t a g el e n g t h s m ak in g adv an ced tu r b o p r o p s l o o k p a r -t i c u l a r l y a t t r a c t i v e f o r t h e s ho rt -a nd -medium-range markets.ADVANCED DESIGN CONCEPTS

Most o f t h e a i r c r a f t s t u d i e s h av e b ee nbased o n e s t i m a t e d p r o p u l s i v e e f f i c i e n c y f ro mt h e p r o p e l l e r n e a r 7 9. 5% a t Mach 0 . 8 . Toa c h i e v e t h i s l e v e l o f p e rf o rm a n ce w i t h a n ac -c e p t a b l e c a b i n n o i s e l e v e l , s e v e r a l a d v a n c e da e r o d y n a m i c a n d a c o u s t i c c o n c e p t s were eval-u a t e d a nd u s e d i n d e s i g n i n g t h e p r e s e n t w in dtu n n e l m o d el s . T h ese co n ce p t s h av e b een d i s -c u ss e d i n p r e v i ou s r e p o r t s ( 1 , 2 , 3 5 - 3 7 ) and w i l lm ain ly b e sum mari zed h e r e . F ig u r e 3 sch em a t i -c a l l y d e s c r i b e s t h e s e i m p or t a n t d e s i g n c o n c ep t sf o r h i g h s p e e d p r o p e l l e r d e s i g n . They i n c l u d er e du c ed b l a d e t h i c k n e s s an d t i p sw ee p t o mini-miz e c o m p r e s s i b i l i t y l o s s e s i n t h e o u t b oa r dp a r t o f t h e b l a d e s a nd t o r e du c e c r u i s e n o i s e ;t a i l o r e d n a c e l l e b l oc k ag e a nd s p i n n e r area-r u l i n g t o r e d u c e b l a d e - t o- b l a d e c h o k i n g a n do t h e r c o m p r es s i b i l i t y l o s s e s i n t h e b l a d e r o otr e g i o n ; a n d , t h e u s e of a dv an ce d a i r f o i l tech-n o i o g y. To h o l d p r o p e l l e r d i a m e t e r an d w e i g h tt o r e a s o n a b l e v a l u e s f o r Mach 0.8 c r u i s e a b o v e9 . 1 4 4 km (30 000 f t ) a l t i t u d e , power ( d i s k )l o a d i n g s s e v e r a l t imes h i g h e r t h a n c o n v e n t i o n a ld e s i g n a r e r e q u i r e d . T he se h i g h l o a d i n g s thenw ou ld r e q u i r e i n c r e a s i n g t h e nu mb er o f b l a d e st o a r o u n d 8 t c 10 t o ke ep i d e a l p r o p e l l e r e f -f i c i e n c y h i g h . A dvan ced p r o p e l l e r l n a c e l l e de-s i g n i s a h i g h l y i n t e g r a t e d p r o c e d u re an d i s

* Num be rs i n p a r e n t h e s e s d e s i g n a t e R e f e r -e n c e s a t en d o f p ap e r .SA E P a p e r So . 790373 J e r a c k i

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d es cr ib e d i n d e t a i l i n K e l . (C). :;n exampleo f t h i s i n t e g r a t e d p r o c e d u r e i s s i i o ~ n n F i g..i w h er e b l a d e s c ie ep , s p i n n e r a r e a r u l i n g a n dn a c e l l e b l o c k a g e a r e u s e d t o minimize com-p r s s s i b i l i y l o s s e s a c r o s s t h e c on iT le te b l a d er a d i u s . F a r a s t r a i g h t p r o pe l l e r a t t h e d e s i g ncond i t ion o f ? tach 0 .8 c r u i s e a nd 2 d 3 . 8 m/sec(SO0 f t / s e c ) b l ad e t i p speed, a l l s ec t i o n re la-t i v e ?tach numbers (curvci A ) a r e a bo ve t h e d r a gdiv erg enc e Xach number (cur ve 3) of t!ie pro-p e l l e r w i t h SACA 1 6 - sc i r is s a i r f o i l s e v en whent h i n b l a d e s e c t i o n s a r e u s es . Adding 30' o fs i ieep (curve C ) b r i n g s :he :-fach numbers neart h e t i p t o v a l u e s 1o :j er t h a n d r a g d i v e r g e n c el e v e l s . A r e a - r d i n g t i 12 s ? l n n e r a n d n a c e l l eb l o z k a g e s u p p r e s s t h e l c c a l Xacn n um be rs i n:he ~ I G ? rsgior. (c1Jrve I)). 2; f t h e a d va n c edaerzayna- ic and acous t i c co r. cepzs t :e re in -.. ,es:igat21 i n t n e i i ind t u n n el m d e l p r og ra md i s c u s s e d h e r s w i t h t h e s x c e p r i o n of advanceda i r f o i l s . Cnder c u r r e n t XASA ? l a x , t h i s c o n -c e p t xi11 b e a d d r e s s e u i- :?.e filtzre.g s a l s , n c a r - f i e l d soc~-; i- c o i s e c a r g e t l e v e l swere e s t a b i i s h e i L O kee; i ~ . c e r i o rn Q i se l e v e l sc o m p e t i t i v e x i t h c u r r e n t \;ice body a i r c r a f ta nd t o n i n i m i z e t h e n e ed f c r f u s e l a g e t r e a t -a e n t . S i n c e t h e b l a d e r e l a t i v e t i ? Xach num-5 e r s a r e s l i g h t i y s u p e rs o ni c a s sho7.m i n F ig .4 ( ? ITIp 2 1 . 1 4 ) t h e i n i t i a l a p pr sa ch f o r n o i s er e d u c t i o n was t o add srceep and red uce th es f f e c t i v e l o c a l s e c t i o n >:act n un be r t o b el owt h e s e c z i o n c r i t i c a l Yach n n x be r . The s h o cks t r e n g t h a nd t k e r e f o r e t . .e r e s u l t i7 . g p r e s s u r e; d j e i s t h e r e h y r e d u c e d . 1;;;-0 t i p s ve epb l r 3 e 6 e s i 3 n s w e re e x p s c i e d :> b e aonewhat; u i e ze r f z r t h i s re a so r ,. .i more advanced con-c s ~ c as i n z o rp o r a te d i n a $ 5 t i p s weep de-s i g n iSX-3) u s i n g t h e l i - e a r a c c u s c i c a n a l y s i sof Xef. ( 3 8 ) . .A h i s t o r i c a l 2 e v e l o ; m e n t o f t h ez p ? i i c & : i o n of a c o u s t i c t h eo r ; - to advancedp r o p e l l e r d e s i g n i s g i v e n i r , R e f . (39 ) . Thep r e s e n t t h e o r y p r e d i c c s t h i c k n e s s ( du e t o b l a d ea i r f o i l t h i c kn e ss d i s t r i b u t i s n ) and l o a d in g( du e t o p r e s s u r e l o a d s o n t h 2 h l a d e a i r f o i l )n o i s e c om po ne nt s f ro m e a c h r a d i a l s e c t i o n oft h e b l a d e . T h i c k n es s m i s e i s g e n e r a l l y t h ed o m i n a n t n o i s e s o u r c e or , a p r o p e l l s r o 2 e r a z i n gw i t h a s l i g h t l y s u p r s o n i c ti? Zhch number.By p r o p e r l y s we e pi ng t h e b l a d e ? i a z f or m i t i sp o s s i b l e t o r e du c e n e a r - i i e l 2 n o i s e u si n g t h e?base i n t e r fe r e n ce c on ce pt i l l u s t r a t e d i nF i g . 5. The n o i s e f r o m o ne T r o p e l l e r b l a d e i s

1 & i d i t i o n ti-,; ;7q7,.-- I * L A > -:..-'c e f f i c i e n c y

0

t h e v e c t o r s u n o f t h e c o n t r i b u t i o n s of t h es i n u s o i d a l wave ( a m p l i t u d e a n d p h a s e a n g l e )f ro m e a c h r a d i a l s t r i p . The n o i s e of t h e t o t a lp r o p e l l e r i s t h e p r o d u c t of t h e v e c t o r sum andt h e nu mbe r o f b l a d e s . S we e pi n g t h e t i p backc a u s e s i t s s i g n a l t o l a g ( i n c re a s e d ph a sea n g l e ) t h e s i g n a l f ro m t h e mid b l a d e r e g i o nt h us c a us i ng p a r t i a l i n t e r f e r e n c e a nd a re -d u c t i o n i n n o i s e . T h i s ph a s e i - n t e r f e r e n c e c on -c e t was u se d i n t h e a c o u s t i c d e s i g n o f t h e45 s we p t p r o p e l l e r m od el (SR-3) t o r e d u c e t h en e a r - f i e l d c r u i s e n o i s e . T h i s c o nc e pt s h ou l dh av e a p p l i c a t i o n t o b o t h t h i c k n e s s a n d l o a d i n gn o i s e i n t h e ne a r and f a r f i e l d s .

8

YODEL DESIGN Ah3 TESTSI n i t i a l d es ig n s t ud i e s ( 3 6 ) f o r h i ghs p e e d p r o p e l l e r s w e r e b a s e d on com par i s onsw i t h p r e s e n t d ay t u r b o f a n p ow er ed t r a n s p o r t s ,w i t h t h e r e q u ir e me n t t h a t a i r p l a n e sp e ed , c a b i ne n v i r on m e n t , an d a i r p l a n e s a f e t y n o t b e d e-g r a de d w i t h a n ad va n ce d f u e l e f f i c i e n t t u r b o-

pr op . The de si gn Ziach number of 0 .8 a n d a l t i -t u d e o v e r 9 . 1 4 4 km (3 0 00 0 f t ) w a s e s t a b l i s h e dt o a l l o w t u r b o p r op p owe re d a i r c r a f t t o meshw i t h t u r b o f a n p ow er ed a i r c r a f t . H ig h p r o ? e l l e rp ow er ( d i s k ) l o a d i n g i s r e q u i r e d wi t h o ut t h es i z e an d w e i g h t p e n a l t y a s s o c i a t e d w i t h co n-v e n t i o n a l p r o p e l l e r d e s i g ns t o a c h i e v e t h eMach 0 .8 , 10 . 668 km (35 000 f t ) d e s i g n p o in t .A l l t h e a dv an ce d p r o p e l l e r d e s i g n s t h a t weret e s t e d h ad e i g h t b l a d e s w i th b l a d e a c t i v i t yf a c t o r s n e a r 200 ( e x c e p t 235 f o r SR-3) t o meett h i s h ig h io a d i ng r eq u ir e me n t. I n o r d e r t ok ee p t h e a i r p l a n e c a b i n n o i s e c o mp ar ab l e t op r e s e n t t u r b o f a n ? ow er ed a i r c r a f t , a n a e ro dy -namic - acous t i c com prom is e was r e ac h e d i n t h ei n i c i a l p r o p e l l e r d e s i g ns w hi ch a l l o x e d t h er e l a t i v e t i p Xach number t o b e s l i g h t l y s u p e r-sonic (approx. ZIach l.l+). The des ign param-e t e r s f o r t h e f o u r model p r o p e i l e r s t h a t weret e s t e d a re shown in F i g . 6 a i o n g w i t h t h e ?re-d i c t e d d e s i g n p oi At e f f i c i e n c i e s f r om t h e ne ch -od of Ref . (i). A l s o , t h e ? r e a i c t e d c r u i s en o i s e u s in g t h e a c s u s t i c a n a l y s i s o f 2 e f . (39)a t : L i g b , t c z r . l % t i x s a x L dis-----d' .Ld si 2 . 3 3,s-2el;e: l i a r r , s t c r s ~ Z G T . L-.z c? :a >.-.>.c..

.is :as 5, s e ? ~ , ;? s p r e c , 20a nd b l a d e c um be r f o r a l l f o u r c e s i g s w z r e t h esame, t h e r e f o r e i l e a l e f f i c i e n c y was t h e sainef o r a l l of t h e d e s i g ns . A l l des igns ixad th ina i r f o i l s w i t h w i de c h o r d s an d h ad t w i s t and

- _

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c am be r d i s t r i b u t i o n s w h i ch we r e b a s e d on t h ep r o p e l l e r o p e r a t i n g i n t h e f l o w f i e l d a ro un da s p e c i f i c s p i n n e r a nd n a c e l l e . C o n fi g u ra t i onSR-2 w a s a s t r a i g h t b l a de w hi ch w a s d e s i g n e dan d t e s t e d w i t h a n ar e a -r u l ed s p i n n e r (AR-2).SR-1 ha d 30 o f t i p s we ep a nd w a s d es ig n ed an dt e s t e d v i t h a c o n i c s p i n n e r (C-1). SR-lm wasa m o d i f i c a t i o n o f t h e S R-1 d e s i g n w i t h h i g h e rl o a d i n g n e a r t h e t i p . A s s h o w i n F ig . 7 ,t h i s w a s a c c o m pl i s h e d b y r e d u c i n g t h e t w i s ta nd i n c r e a s i n g t h e c a n b e r n e a r t h e t i p com-pa re d t o SR-1. SR-lm was t e s t e d w i t h b o th t h eco n ic a l an d a r ea - r u l e d s p in n e r s . SR-3 h ad 45o f t i p sweep and w a s t h e m os t ad v an ced d e s ig ns o f a r . The a c o u s t i c p h as e i n t e r f e r e n c e con-c e p t d i s c u s s e d e a r l i e r w a s u se d i n t h e d e s ig no f t h e p l a n f o r m sh ap e ( ch o r d an d sweep ). SR-3was p r e d i c t e d t o h av e a n o i s e l e v e l a bo u t 6 dBb el ow t h e s t r a i g h t b l a d e d SR-2 d e s i g n . SR-3w a s d e s i g n e d an d t e s t e d w i t h a n a r e a - r u l e dsp inner (AR-3) . A s sho wn i n F ig . 6 , t h e p r e -d i c t e d d e s i g n p o i n t e f f i c i e n c y i n c r e as e d ast h e amount of sweep was i n c r ea se d . The b l ad eg eo me tr y c h a r a c t e r i s t i c s f o r a l l f o u r b l a d ed e s i g n s a r e shown i n F ig . 7. A i r f o i l s e c t i o nsf o r t h e b l a d e d e s ig n s ;.:ere NACX s e r i e s - 1 6 f r o mt h e t i p t o t h e 53 % r a d i u s (454 o r SR-1) andXACA s e r i e s 65 w i th c i r c u l a r a r c mean l i n e(3AC.A a = l mean l i n e f o r SR-1) f r o m t h e 37%r a d i u s t o t h e r o o t wi t h a t r a n s i t i o n f a i r i n gb e tween .

A t t h e i r d e s i g n a dv an ce r a t i o (J = 3.06)a n d p o w e r c o e f f i c i e n t ( C p = 1 . 7 ) t h e p r e d i c t e de f f i c i e n c i e s a r e p r e se n t ed i n F i g . 8 a t f r e e -stream ?lach numbers froin 0 . 6 t o 0.85. Fo rr e f e r e n ce t h e i d e a l e f f i c i e n c y l e v e l (85.1%)i s shown which w a s b a s e d o n an op t imum b ladel o a d i n g w i t h z e r o b l a d e d r a g. The p r e d i c t e de f f i c i e n c i e s were a l l h i g h a t low Mach num-b e z s w i t h t h e 45 sweep S R - 3 p r o p e l l e r a n d t h e30 sweep SR-lm p r o p e l l e r j u s t ab o u t 1% bovet h e 30 sweep SR-1 and 0 sweep SR-2 p r o p e l l -e r s . S i g n i f i c a n t d i f f e r e n c e s a s s o c i a t e d w i t hsweep appeared above Mach 0 . 7 . The 30 sweptc o n f i g u r a t i o n s s h o w e d a b o u t a 2 % improvementcompared t o t h e s t r a i g h t SR-2 p r o p e l l e r . The45 sweep SR-3 p ro p el l e r showed even h i g h e rp e rf o rm a nc e an d t h e p r e d i c t e d e f f i c i e n c y re -mained above 80% o u t t o Mach 0.85.The 62.2 cm ( 2 4 . 5 i n . ) d i a me t e r p r o p e l l e rmodels were a l l t e s t e d i n t h e XASA L e w i s 8-by-6f o o t w in d tu n n e l ( 4 0 ) o n t h e 1000 h p p r o p e l l e rt e s t r i g ( P T R ) . F i g u r e 9 s h o u s t h e 45O sweptSR- 3 m o d e l i n s t a l l ed or, t h e P T R . A cu taway

0

drawing oL t!ie PTR i s shown i n F i g . 1 0 . Thep r o p e l l e r m od el s we r e d r i v e n b y a t h r e e s t a g ea i r t u r b i n e u s i n g a 3 . 1 0 3 ~ 1 0 N/ m (450 p s i )c o n t i n u o u s f l o w a i r s u p p l y s y s t e m . F o r c e s ont h e p r o p e l l e r a nd s p i n n e r s were m easu r ed u s in gt wo s e p a r a t e s y s t e m s . A l o a d c e l l l o c a t e d I nt h e v e r t i c a l s t r u t was u s e d t o measure ax i a lf o r c e . A r o t a t i n g b a l an ce l o c a t e d j u s t a f t oft h e s p i n n e r me a su r ed b o t h t h r u s t a nd t o r q u e .N a c e l l e f o r c e s were d e t e r mi n e d f r o m p r e s s u r ei n t e g r a t i o n .The wind tu nn el t e s t s were co n d u c ted a tz e r o mo de l i n c i d e n c e t o t h e f r e e - s t r e a m f l o w .The b l ad e an g le m easur ed a t 3 1 4 p r o p e l l e rr a d i u s (B3/4) was s e t a t v a r i o u s a n g l e s a n dd a t a were t a k e n o v e r a r a n g e i n Mach numberfrom 0. 6 t o 0.85.

6 2

AERODYNAMIC TEST RESULTSTh e w in d t u n n e l p e r f o rm a n c e d a t a i n t h i sp a p e r a r e p r e s e n t e d i n terms o f p r o p e l l e r n e te f f i c i e n c y . T h a t i s , t h e p r o p ul s i ve e f f i c i e n c yo f t h e p r o p e l l e r b l a de s a l o n e , a f t e r c o r r e c t i n gf o r i s o l a t e d s p i n n e r d r a g a nd t h e bu oy an cy i n -t e r a c t i o n f o r c e f r o m t h e n ea r by nacel le . Theb uo ya nc y c o r r e c t i o n f o r c e was d e t e r m i n e d u s i n gthe method of Refs . ( 4 1 ) t o ( 4 3 ) . Net e f f i -c i en c y ( I NE T) an d po wer c o e f f i c i e n t (Cp) p l o t s

a t Mach 0.6 and 0.8 a r e p r e s e n t e d i n Fig. 11f o r SR-3. T h e c o e f f i c i e n t s were b ased on ar e f e r e n c e p r o p e l l e r d i a me t er o f 6 2 . 2 c m (24.5i n . ) which w a s t h e a c t u a l d i a m et e r w i t h theb l a d e s i n t h e a p p r ox i ma t e f e a t h e r p o s i t i o n .F o r t h e s w e p t m o de l s t h e d i a m e t e r a t c r u i s eb l a d e a n g l e s was s l i g h t l y l a r g e r t ha n t h i s .The p r o p e l l e r d i a m e t e r c ha n ge s w i t h b l a d e a n g l es e t t i n g d ue t o th e b lad e sweep .p r o p e l l e r s were o p e r a t e d a t a number of powerl e v e l s t o o b t a i n t h e v a r i a t i o n o f n e t e f f i -c i e n c y a nd po we r c o e f f i c i e n t w i t h a d v an e r a t i ob e w r i t t e n i n terms o f pr o p e l l e r c o e f f i c i e n t sa nd f r e e - s t r e a m c o n d i t i o n s a s :

A t eac h b la de a ng le and Mach number th e

s ho wn i n F i g . 11. Po wer l o ad in g (SHP/D 5) c a n

From t h i s r e l a t i o n s h i p l i n e s o f c o n s t a n t powerl o a d i n g have b e e n a dd ed t o F i g . 11 as ercen t-(= 0.05933) d e t e r m i n e d a t t h e d e s ig n o p e r a t i n ga g e s o f d e s i g n l o a d i n g p a r a m e t e r C p/ J5

J e r a c k i3

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c o n d i t i o n s o f J = 3.06 and Cp = 1 . 7 . Per-formance a t c o n s t a n t power l o a d i n g were p l o t t e df r o n t h e s e b a s i c d a t a c u r ve s . The e f f e c t o fp a r e r l o a d i n g a nd a dv a n ce r a t i o on n e t e f f i -c i e z c y a t ?lac:'- 0 . 6 and 0 . 8 i s shown i n F ig s .1 2 2nd 1 3 , r e s ? e c t i v e l y . Eac h p r o p e l l e r /s p i n n e r c o x b i n a t i o n t n a r was t e s t e d i s pre-sen:ed a s a s e p a r a t e ? l o t . T:;pical v a r i a t i o nof e f f i c i e n c y w i t h ad va nc e r a t i o a t a c o n s t a n tpower loading i s a. peaked c . xve . The r e duc t i onf ro m t h e p ea k w i t h i n c r e a s i n g a d v an c e r a t i o i sdu e t o a c o m b i n a ti o n o f l o w e r i d e a l e f f i c i e n -c i e s due t o i n c r e a s e d swirl 2nd lower b la des e c t io n a l l i f t t o d r a g r a t i o s ( f ro n i nc re as in gl o c a l a n g l e s o f a t t a c k ) . The f a l l - o f f w i t hd e c r e a s i 2 g ad va nc e r a t i o i s d ue t o i n c r e a s e dc o n ? r e s s i b i l i t y l o s s e s z s s c c l a t e d w i t h t h ej i g h e r t i p r o t a t i o n a l s p ee d s a n d/ o r a g a i n l ow erb la de se c t i o n a l l i f t ts d r a g r a t i s s ( fr om de -c r e a s i n g l o c a l a n g l e s of a r z a c k ) .a d va nc e r a t i o s a p p ea r ed y o r e s e v e r e f o r t h es t r a i g h t SR-2 n o d e l t h a n f o r t h e s we pt c o n f i g -u r a t i o n s C o s t l i k e l y i n d i c a : i n g e a r l i e r o n s e tof c o x p r e s s i b i l i t y losses iz t h e b l ad e t i p re-gior,. Z.t botb. Xach 0 . 6 an? 0 . 8 SII - lm appear -e d t o h a ve l e s s ?erfor-.ancs Loss a t t h e h i g ha d v a n c e r a t i o s t h a n Sil-1 w:?ich a a y b e d ue t o anore o?timurn twist ar.2 cainjer d i s t r i b u t i o n .A d d i t i o n o f t h e a r e a - r u l e d s ? i n n e r t o the SR-lmm odel inp rove d t he per fo rm ance a t Xach 0.8from ic w t o h i g h a d v a n c e r a r i o s i n d i c a t i n g a2 o s s i b i e r e d u c t i o n i n losses i n t h ? b l ad e r o o tr eg id? . ;he L5L swe?- , model (SR-3) which had271 a r z a - r u l e d s ? i n n e r a p p e a r e d t o g e t mos t o fICSe r f s r m a n c e b e n e f i t a t low ad:.ance r a t i o s ,w hm c o np a r ed t o t h e j e s t 3C' swept model( S R - l a ) r ;i th t n e a r e a - r u l e d s p i n n s r . T h i s i n -d i c a t e s b e n e f i t f ro m t h e i n c r e a s e 3 s weep i nr e d u c i n g o n s e t of c o c p r e s s i k i l i t y l o s s e s a tt h e bl a d e t i p s .;n g e ne r al t h e e f f e c t of reduced powerl o a d i n g I J ~ S n im provemen t i n pe r fo rm ance .Iiowe ver, t h e a i r c r a f t t r a d e o f f t h a t o c c ur s i si n cr e as e d p r s p e l l e r s i z e w h L ~ h a n a f f e c t t h eo v e r a l l a i r p l a n s d e s i g n a nd ;nay c a u s e i n -c r e a s e d w e i g ht a nd c o s t p e n a i t i e s . The in-cre ase d p erfor mance may more tha n make up f o rt h i s p e x a i t y , b u t t h i s w i l l depend on t h es p e c i f i c a p p l i c a t i o n . A t h o r o u g h a i r p l a n e m i s -s i o n a n a l y s i s s t u dy c a n d e t e r mi n e t h e d e s i r a -b i l i t y o f m od if yi n g t h e p r o p e l l e r " de si g nF o i nt " t o o p t i m i z e t h e o v e r a l l p er f or ma nc e .

A t :.iach G . 8 t h e 2 e r f o r r n c e d ro p a t low

Performance a t t h e 100%power loa d i ng andd e s i g n a dv a nc e r a t i o o f 3 .0 6 were o b t a i n e d f r o mt h e c r o s s p l o t s i n F i g s . 1 2 and 13 , a n d a l s o a tother Xach numbers from s i m i l a r c r o s s p l o t s . Ades ign load ing per fo rm ance s um m ary o f measuredne t e f f i c i en cy over t he Mach num ber r ange f r o m0 . 6 t o 0 . 85 i s p r e s e n t e d in F i g . 1 4 . Comparingt h e c o n f i g u r a t i o n s a t M a c h 0 . 8 i n d i c a t e s t h a te a c h s t e p i n d e s i g n i mp ro ve me nt d i d y i e l d a ni mp ro ve me nt i n e f f i c i e n c y t h a t a p p r o a c h e d t h es t u d y v a l u e s u se d i n f u e l e f f i c i e n c y c om pa ri -s ons be tween tu rboprop and tu rbofan powereda i r c r a f t .y i e l d e d a b o u t 1%mprovement ( 7 7% ) o v e r t h es t r a i g h t SR-2 b lad e e f f i c i en cy o f 75 . 8%. Add-i n g t h e a r e a- r u le d s p i n n e r t o SR-lm improvedi t s p e r fo r ma n c e a b o u t a n a d d i t i o n a l p e r c gn tt o n e a r 78%. The SR-3 model w i t h i t s 45 ofs we ep a n d a r e a - r u l e d s p i n n e r h ad t h e h i g h e s tper fo rm ance ( 7 8 . 7 % ) a t the design Mach numberof 0 . 8 and h ad s i g n i f i c a n t b e n e f i t o u t t oNach 0 .85. The improvement ove r th e SR-2 (0's w e e p ) c o n f i g u r a t i o n w a s a b o u t 3% a t d e s i g n .A t Mach 0.6 and 0 . 7 t h e SR-lm (30' sweep) andSR-3 (45' s we ep ) c o n f i g u r a t i o n s h a d n e a r l yt h e same e f f i c i e n c y of a b o u t 81%. These re-s u l t s a r e q u i t e e n c o u r a g in g a nd f u t u r e m od el sw i t h 1 0 b l a d e s a n d lower power lo ad in g s hou ldhave even h i ghe r pe r fo rm ance .

The 30' swee p of SR-1 and SR-lrn

ACOUSTIC TEST RESULTSI n a d d i t i o n t o t h e p e r fo rm an ce d a t a ,a c o u s t i c m e as u re m en t s were a l s o made i n t h eLewis 8-by-6-foot wind tu nn el on t h e f o l l o w -i n g m o de l s: SR-2 (0 sweep) , SR-lm (30'swe gp ) w i t h t h e z o n i c a l s p i n n e r , a nd SR-3

(45 s w e e p ). T h es e d a t a were o b t a i n e d f r o ms i x w a ll - an d -c e il i ng - mo u nt e d p r e s s u r e trans-d u c e r s a s s hown i n F i g . 1 5 . Xeasurementswere made with t i e p r o p e l l e r s o p e r a t i ng a tnear -de s ign co nd i t i on ove r th e Mach numberr a n g e f ro m 0 . 6 t o 0 . 8 5 , a n d a l s o a t f e a t h e rco nd i t i ons f o r the SR-3 mode l. Though th ep o ro u s- w al l e d t u n n e l d o e s n o t h a ve a c o u s t i cdamping m a t e r i a l on any of i t s w al l s and ab-s o l u t e n o i s e l e v e l s may b e s u b j e c t t o q u es -t i o n be c a us e o f r e f l e c t i o n s , t h e d a t a ob-t a i n e d i nd i c a t e d t h a t i n f o r m t i o n a bo ut t h en o i s e d i f f e r e n c e s among t h e t!iree p r o p e l l e r sw a s u s a b l e .w i t h a bandwi6 th o f approx im at e ly 2 6 Hz, a r e

0

Xar row band an a l ys i s f rom 0 t o 10 00 0 Hz,

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p r e se n t e d i n F i g. 1 6 comparing SR-3 (45'sweep) a t c r u i s e a nd f e a t h e r c o n d i t io n s f o r ac e i li n g -m o un t e d t r a n s d u c e r s l i g h t l y d o wn st re amo f t h e p r o p e l l e r p l a n e . The p r o p e l l e r b l a d epas s age tone and harm onics a r e v i s i b l e a b o v et h e b a ck gr o un d l e v e l ( b l a d e a t f e a t h e r ) i n -d i c a t i n g t h a t t u n n e l b a ck gr ou nd n o i s e was n o ta p r cb le m i n c om pa ri ng r e l a t i v e t o n e l e v e l s .Though i t i s n o t p o s s i b l e t o p r ov e c o n c l u-s i v e l y t h a t t h e t u nn e l n o is e d a t a a r e f r e eJ f r e f l e c t i o n ca us ed e r r o r s , t h e r e a r e i n d i -c a t i o n s t h a t t h e pr ob l em v a s n o t s e v e r e .T h e r e was s i g n i f i c a n t d i r e c t i v i t y i n di c a te dby t !-,e c e i l i n g p r e s s u r e s f u r t h e r do cu me nt ed i nRef . ( i s ) . D at a f ro m t h e s i d e v a l l t r a n s d u c e r sa l s o i n d i c a t e d a r e d u c t io n i n n o i s e l e v e l w i t hd i s t a n c e . D i r e c t i v i t y and n o i s e f a l l o f f w i t hd i s t a n c e i n d i c a t e t h a t t h e t u n n e l r e f l e c t i o n sd 3 2 3 t e v e r y w n e r e d o m i n a t e d i r e c t i n c i d e n tn o i s e s i g n a l s . I t ma); b e t h a t t h e t u n n e lb l e e d h o l e s a nd h i g h t u n n e l - : el o ci t y d i d n o ta l l ot ; t h e b u i l d u p o f a h i g h r e v e r b e r a n t l e v e l .T he se o b s e r va t i o n s i n d i c a t e t h a t a t l e a s tr e l a t i v e t o n e l e v e l c o n 7 a r i s o n s b e t w e e n b l a d ed e s i g n s a r e good.

.A compar ison o f m e a s u r e d n o i s e r e d u c t i o nr e f e r e n c e d t o SR-2 (0' sweep) i s g i v e n i nF i g , 1 7 f ro m t r a n s d c c e r p c s i r i o n 3 . S R - l m(30' sweep) i s s e e n t o ha ve b ee n s l i g h t l yq u i e t z r tha n SR-2. The aerodynamic sweep ofSR-lm was e x pe c t ed t o r e du c e t h e n o i s e l e v e lsomewiiat due to lower s t rengtk shogk ' . caves ont h e 3 0 s w ep t b l a d e t i p . SR-3 (45 sweep) w a sa b o u t 5 t o 6 dB qu ie te r than SR-2 a t t h e b l a d ep a s sa g e t o n e. T h i s s i g n i f i c a n t n o i s e r ed uc -t i o n was i n go od a gr e e me n t w i t h t h e p r e d i c t e dv a l u e f r o m t h e a c o u s t i c a n a l y s i s p r o g r a m( F i g . 6 ) , w h er e a p h a se i n t e r f e r e n c e c o n c e ptw a s u s e d t o a c o u s t i c a l l ; ; d e s i g n S R-3.

0

FUT!RZ PLANSThe advanced tu rbop rop p r o j ec t ha s beenf o c u s e d on t h e t e c h no l o gy n e e d s of f u t u r e a d-v a n ce d c o n m e r c i a l a i r c r a f t . H ow ev er , t h e e n-c s u r a g i n g p r o p e l l e r p e r f o rm a n ce an d n o i s e re -s u l t s p re s e nt e d i n t h i s p a pe r s h o u ld ha ve a p-p l i c a t i o n t o b u si n e ss a i r c r a f t e s p e c i a l l yt h o s e i n t h e h i g h e r p e r fo rm a nc e c a t e g o r i e s .F u t u r e NASA p l a n s f o r t h i s p r o j e c t i n c lu d et e s t i n g o f f o ur a d d i t i o n a l p r o p e l l e r m o d e l s

t h a t w i l l e v a l u a t e t h e f o l l o w i n g a d v a n c e df e a c u r e s : i n c r e a s e d b l a d e n umb er , a e r o a c o u s t i c

a i r f o i l s , l o w er powe r l o a d i n g an d a l t e r n a t ed e s i g n c o n d i t i o n s , a nd i n c r e a s e d s we e p. Se v-e r a l a dv a n ce d p r o p e l l e r a e r od y na m ic a n da c o u s t i c a n a l y s i s p ro gr am s ha ve r e c e n t l y b ee nd e v el o p ed o r a re u n d e r d ev e l op m en t t h a t s h o u l de n h an c e t h e d e s i g n o f t h e s e new m o d el s . Thesep ro gr am s i n c l u d e : a n i n t e g r a t e d p r o p e l l e r /n a c e l l e a n a l y s i s f o r s i n g l e a nd d u a l r o t a t i o np r o p e l l e r s , a t h r e e d i m e ns i on a l t r a n s o n i c l i f t -i n g s u r f a c e a n a l y s i s , a nd a f r equency dom aina c o u s t i c a n a l y s i s w i t h n o n l i n e a r q u a dr u po l en o i s e s o u r c e s ( 3 9 ) . I n a d d i t i o n t o t h e p l an ne dwo rk i n a e r o d y n a mi c s a n d a c o u s t i c s , t h e Ad-vanced Turboprop P ro jec t w i l l a d d r e s s a d -v an ce d t e c hn ol o gy i n p r o p e l l e r a e r o e l a s t i c s ,b l a d e s t r u c t u r e s a nd f a b r i c a t i o n t ec h n i qu e s .The advanced p ro pe l l e r t echno logy work undert h i s p r o j e c t c a n b e e xt e nd e d t o l o w e r sp e e dg e n e r a l a v i a t i o n a i r c r a f t . Work p r e s e n t l yunderway a t NASA a n d i n c l u d e d i n p l a n s f o r ap r o g r a m c a l l e d GAP, f o r G e n er a l A v i a t i o nP r o p e l l e r t e c h n o l o g y , t r e a t s p e r f o r m a n c e ,n o i s e , a e r o e l a s t i c s , a nd c o mp o si t e s t r u c t u r e si n t h i s l o w er s p ee d r an g e .CONCLUDING REMARKS

F o r t h e a d va n ce d t u r b o p r o p t o b e c o m pe t i -t i v e w i t h p r o p o s e d a dv a n ce d t u r b o f a n p ow er eda i r c r a f t , i t m ust h a v e h i g h p r o p u l s i v e e f f i -c i e n c y a t Mach 0 . 8 c r u i s e a b o v e 9 . 1 4 4 km(3 0 000 f t ) a l t i t u d e wi t h a n a c c ep t a bl e c a b i nn o i s e e n v ir o n me n t . T h i s g o a l r e q u i r e s t h ei n c o r p o r a t i o n o f s e v e r a l advanced ae rodynam ica nd a c o u s t i c c o n c e p t s . The p r o p e l l e r n e e dst o b e de si g ne d i n t e g r a l l y wi t h t h e l o c a ln a c e l l e f l o w f i e l d a nd t a k e a d v a nt a ge o f a l lt h e a e r o d y na m i c s u p p r e s s i o n p o s s i b l e t o o v er -come t h e i n h e r e n t c o m p r e s s i b i l i t y l o s s e s a tt h e s e h i g h c r u i s e s p e e d s . F o ur 8 - bl a d ed p r o-p e l l e r m o d e l s were d e s i g n e d e m p l o y i n g v a r i o u sc o n c e p t s t o r e d uc e c o m p r e s s i b i l i t y los ses .R e s u l t s f r o m t h e wi nd t u n n e l t es t s were en -c o u r a g i n g . E ac h d e s i g n c o n c e p t a p p e a r e d t og i v e so me p e r f o r m an c e b e n e f i t . T he aero-a c o u s t i c a l l y d es i gn e d c o n f i g u r a t i o n ( S R - 3 )w i t h 45' o f t i p s we ep a n d a n a r e a - r u l e d s p i n -n e r y i e l d e d t h e h i g h e s t p r o p u l s i ve e f f i c i e n c y( 7 8 . 7 % a t Mach 0 .8 , 3 .06 a d va n ce r a t i o , a nd1 . 7 p ow er c o e f f i c i e n t ) , w i t h a n i mp r ov e me n to f a p p r o x i m a t e l y 3 % o v er t h e s t r a i g h t bl a de dc o n f i g u r a t i o n ( S R - 2 ) . T h e p h a s e - i n t e r f e r e n c e ,c o nc e p t f o r n o i s e r e d u c t i o n u se d i n SR-3

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y i e l d e d a b o u t 5 t o 6 d B r ed u c t io n co mp ar ed to dCT/d( r /R)S R - 2 . Advanced aerody namic and ac ou st ic de-sign t e c h n i q u e s h a v e i m p r o v e d p r o p e l l e r p e r -f o r m a n c e s i g n i f i c a n t l y f o r h i g h speed a p p l i -v an ce d a i r f o i l s , i n c r e a s e d s w ee p, l a r g e r b l a denumber, and lower t i p sp ee ds and power loa d- LHir?gs cap b e e x p e c t e d t o make f u r t h e r p r o g r e s si n t h i s i mp or ta nt area o f T o r e en e r g y -

c a t i o n s . C o nt i nu e d r e f i n e m e n t i n c l u d i n g a d- J

e f f i c i e n t p ro p ul s i o n s ys t e ms . LVSY?!BOLSAAF

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dBdCp!d (r!R)

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a s pe c t r a t i oe l e m e n t a l b l a d e c h o r d , (:in ( i n . )p o w e r c o e f f i c i e n t = ? / c n D 5o XEFe l em e nt a l b l a de d e s i g n l i f t c o e f f i -c i e n ti -n te gr at ed d e si g n l i f t c o e f f i c i e n t

2 4o REF: : r u s t c J e f f i i i e n t = n i~

b la de t i p d i a x e t e r , cn ( i n . )d i r e c t o p e r a t i n g c o s tr e f e re n c e b l a d e t i p d i a me t er = 6 2 . 2cm ( 2 A .5 !1 2 f t )d e c i b e le l e me n t al p o ke r c o e f f i c i e n t

p p = [dCp/d(r/R)] d(r/R)]

PPTRRrS H P

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[cT = [(dCT/d (r/R)) d k/N]VO/nDREFd v a n c e r a t i o ,

h o r i z o n t a l d i s t a n c e f ro m PTR c e n t e r -l i n e , cm ( i n . )v e r t i c a l d i s t a nc e f rom PT R c e n t e r -l i n e , c m ( i n . )Mach numberl o c a l Mach numberfree-stream Xach numberr o t a t i o n a l s p e ed , r e v o l u t i o n s p erseco n dpower, kW ( f t - l b / s e c )p r o p e l l e r t e s t r i gb l ad e t i p r a d i us , c m ( i n . )r a d i u s , c m ( i n . )s h a f t po we r, kW ( hp )s i n g l e r o t a t i o nt h r u s t , n ew to ns ( l b )e l e r ce n t a l b l a d e t h i c k n e s s , cm (in.)l o c a l v e l o c i t y , m/sec ( f t / s e c )f r e e - s t r e a m velocity, m/sec ( f t / s e c >b l ad e r o t a t i o n a l t i p v e l o c i t y , m/sac

( f t / s e c )a x i a l d i s t a n c e f ro m p r op e l l e r p l an e

of r o t a t i o n , cm ( i n . )b l a d e a n g l e a t 7 5 t r a d i u s , dege f f e c t i v e b l a de t w i s t , deg

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APPv' i

'net

apparent efficiency = (TApp ' LrUj/P

ideal propulsive efficiency =* V ) / P (excludes(Tideal .oblade profile drag and compres-sibility losses)

net efficiency = (Tnet vo) / l 'nominal a n g l e of pressure trans-ducer position from propeller,

degfree-s:rean density, kglm3 (slugs/f t3)phase angle

REFEESCES1. D. C. blikkelson, et al., "Design andPerforxance of Energy Efficienr Propellers for

Yacn C.8 Cruise." NASA TN X-73612, 1977.Tn. 3 . Adamson, "Prop-Fan Propulsion - ItsStatus and Potential." SAE Paper 780995, SAEAerospace Yeeting, San Diego, Nov. 1978.iiminary Study of Advanced Turboprops for LowEnergy Consumption." NASA TM >;-717;0, May1975.Transports Using the Prop-Fan Concept." Boe-ing Commercial Airplane Co., 86-75780, Oct.

2 . J. F. Dugan, Jr., B. S. Gatzen, and

3. G. A . Kraft and W. C. Strack, "Pre-

:. "Energy Consumption Characteristics of1976; also XASA CR-137937.

5. R. Hirschkron and R. E. Seitzel, "Al-ternative Concepts for Advanced Energy Con-servative Transport Engines." SAE Paper760536, SAE Air Transportation Fleeting, NewYork, Yay 1976.R. P. Johnston, "Study of Unconventional Air-craft Engines Designed for Low Energy Consump-tion." General Electric Co., R76AEG597, Dec.

6. R. E. Neitzel, R. Hirschkron, and

1976; also XASA CR-135136.;. D. E. Gray and J. W. Witherspoon, "FuelConserlTative Propulsion Concepts for Future AirTransports." S A E Paper 760535, SAE Air Trans-portation Meeting, New York, May 1976.

8. D. E. Gray, "Study of UnconventionalAircraft Engines Designed for Low Energy Con-sumption." Pratt & Whitney Aircraft, PU-5434,June 1976; also NASA CR-135065.Key to Fuel Conservation: An Aircraft Manu-facturer's View." SAE Paper 760538, SAE AirTransportation Meeting, New York, May 1976.

10. R. L. Fass and J. P. Hopklns, "FuelConservative Potential for the Use of Turbo-prop Powerplants." SAE Paper 760537, SAE AirTransportation Meeting, New York, May 1976.11. J. P. Hopkins and H. E. Wharton, "Studyof the Cost/Benefit Tradeoffs for Reducing theEnergy Consumption of the Commercial Air Trans-portation System Summary Report." Lockheed-California Co., LR-27769-1, Aug. 1976; also

9. J. A . Stern, "Aircraft Propulsion - a

NASA CR-137927.1 2 . J. P. Hopkins, "Study of the Cost/Benefit Tradeoffs for Reducing the Energy Con-sumption of the Commercial Air TransportationSystem Final Report.'' Lockheed-California Co.,LR-27769-2, Aug. 1976; also NASA CR-137926.

Benefit Tradeoffs for Reducing the Energy Con-sumption of the Commercial Air TransportationSystem." United Air Lines, Inc., June 1976;also NASA CR-137891.Benefit Trade-offs for Reducing the Energy Con-sumption of Commercial Air Transportation(RECAT)." United Technologies Research Center,UTRC-R76-912036-17, June 1976; also NASA CR-137878.15. F. W. Bogetz and A. P. Dubin, "Cost/Benefit Trade-offs for Reducing the Energy Con-sumption of Commercial Air Transportation:Final Report." United Technologies ResearchCenter, UTRC-R76-912036-16, June 1976; also

13. R. E. Coykendall, et al., "Study of Cost/

14. F. W. Gobetz and A. A. LeShane, "Cost/

NASA CR-138877.16. D. L. Nored, "Fuel Conservative Aircraft17. E. F. Kraus, "Cost/Benefit Tradeoffs f o rEngine Technology." NASA TM-78962, Sep. 1978.Reducing the Energy Consumption of the Commer-cial Air Transportation System. Vol. 1: Tech-nical Analysis." Douglas Aircraft Co., Inc.,MDC-J7340-Vol-l, June 1976; also NASA CR-137923.

Jeracki7

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J . C . Vanabkoude, "Co.s t/Benefit Trade-o f i s f o r R e du c in g t h e E n er gy C o n j um p ti a n o f t h eCommercial A i r T r a n s p o r t a t i o n S ys te m. Vol. 2:Marke t 2n d Eco no mic An a ly s es . " Do u g las Ai r c r a f tCo. , i n c . , NDC-J7340-Vol-2, Ju ne 19 76 ; a l s o NASA

E . F . Kraus and J . C. i ' anabkoude, "Cos t /CR-13792-.B en rf ;: T ra d e o i f s f o r R ed uc in g t h e Energy Con-s u mp t io n o f t i i d Csmmercia l Air T r a n s p o r t a t i o nS y s t r m . i .01. 3 : Summary tle port ." Doug lasA i r c r a f t Co . , l i i c . , C lDC - J ; 340 , J u n e 1 9 7 6 ; a l s oNASA CR-137925.

1 8 . J . P . Hopkins , "Study of t h e C o s t /B e n e f i t T rad e o f f s f o r R ed u c in g th e Ene rgy Con-sumption of tn e Commercia l A i r T r a n s p o r t a t i o nS y s te m . F i n a l R e p o r t . " Lo ck h eed -C a l i fo rn iaCo ., LR-2T769-2, Aug. 19 76 ; also YASA CR -137926.

j. P . Hopkins and H . E . Kh ar to n , " S tu d yo f t h e C o s t / B e n e f i t T r a d e o f f s f c r R e du c in g t h eEnerg y Cor.sumption of t h e Comrnerical A i r Trans-por: ati on Syst em. Summary Aepo rc." Lockheed-C a i i f a r n i a i o . , LX-27759-1, A G g . 1'9-5; a l s oS.4S.i S3- 7 92 7 .

19. ?. L. F s s s and J . T . Hc;kins , "FuelCsnserva:i;-e ? ~ ~ s n t i a lc r :he Is? o f Turbo-p r o s P > r ; c r p l a n t s . " SAE P a p e r 76 0537, SAE A i rT r a c s p o r t a t i s n I l e e t i n g, N e w York, Yay 1976.

20. " E ne r gy Co ns u mp t io n C h a r a c t e r i s t i c so f Tran s p o r t s Es i n g th e Prop -Fan C cn cept .F i n a l Repor t ." Boeing Commercia l Ai rp l ane" En er gy C o ns u mp ti o n C h a r a c t e r i s t i c s o f T r a n s-p o r t s Us ing th e Prop-Fan Concept . SumnaryRep or t ." Boeing Commercia l Ai rp l ane Co. , D6-75780, S I V . 97 6. a l s o NASA CR-137938.Con se rva t i zn . ' :er i t s o f Advanced TurbopropT r a n sp o r t A i r c r a f t . I ' 1 ,o ck h s ed -C a l i fo rn ia C o . ,iR-23253: Aug. 197 7; a l s o XASA Cii-152096.. iFi -craf t Engines 3es i gne d f o r Lox Energy Con-s u m p t i o n . " P r a t t & Whicney A i r c r a f t , PWA-5434,JuEe 197f7 ; a l s c XASA CR-135065.2 3 . R. E. X e i t z e l , R. H i r s c h k r o n , a n d R . P.J o h n s to n , " S tud y o f Tu rb o fan En gin es Des ig nedf o r Low En erg y C o ns u mpt io n. " Gen e ra l E le c t r i c

C O . , D6-75780, @ c t . 1976; also NASA CR-137937.

2 1 . Z. D . R ev e l1 an d R . H . T u l l i s , "F u el

2 2 . 3 . E. Gra:;, " S tu d y o f Un co n v en t io n a l

C O . , R76AEG432, 4 ug . 19 76 ; >LISA CR-135053.24 . h . E. S e i t z e l , R . Hir s ch k ro n , an d R . P .

J o h f i s to n , " S tu d y of Un co n ven t io na l A i r c r a f t En-g i n e s D e si g ne d f o r Low Energy Consumption."Gene ra l E l e c t r i c Co. ; K76AEG597, Dec. 1976;a l s o NASA CR-135136.

2 5 . D . E . Lray , "Study o f Turbofa n EnginesDes ig n ed fo r Lo w Energy Consumption." P r a t t hI f i i t n ey A i r c r a f t , PWA-5318, May 1 9 7 6 ; NASA CR -135001.A i r c r a f t E ng in es D e si g ne d f o r Lo w Energy Con-s u m pt i o n. " P r a t t & W h i t n e y A i r c r a f t , PUA - 5 4 3 4 ,J u n e 19 76 ; XASA CR-135065.2 7 . R . L. Foss and J . P . Hopkins , "FuelC o ns e rv a t io n P o t e n t i a l f o r t h e l;se of Turbo-prop Powerplanes . " S AE Pa pe r 760537, SAE AirTr an s p o r t a t i o n Mee t in g , May 1 9 7 6.

28 . J . P. Hopkins and H . E . Wharton, "Studyo f t h e C o s t / B e n e f i t T r a d e o f f s f o r R e du ci ng t h eEnergy Consumptian o f the Commercia l A i r Trans-p or t a ti o n System. Summary Rep or t. " Lock'need-Ca l i fo rn ia Co. , LR-27769-1, Aug. 1 97 6 ; a l s o

2 6 . D . E . g ray , " S tu d y of Un co n v en t io n a l

NASA CR-137927.29 . J. P . Hopkins, "Stud;d o f t h e C o s t/

B e n e f i t T r a d e o f f s f o r R e du c in g t h e E ne r gy Con-sumpt ion of th e Commercia l A i r T r a n s p o r t a t i o nS y st e m. F i n a l R e p o r t . " L o c k h e e d -C a l i f o r n i aCo. , LR-27769-2, Aug. 1 97 6; a l s o NASA CR-137926.t o F u e l C o n s e r v a t i o n : An A i r c r a f t Na n uf a c-t u r e r ' s V i e w . " SAE Pa pe r 7605 38, S AE A i r Trans-p o r t a t i o n M e et i n g, Ne w York, May 1 9 7 6 .

31. E. F. K r a us , " C o s t / S e n e f i t T r a d e o f f s f o rReducing the Energy Consumption o f CommercialA i r T r a n s p o r t a t i o n S y st e m. V o l. I : T e c h n i c a lA n a l y s i s . ' D o u g l a s A i r c r a f t C o . , I n c . , NDC-J7340-Vo1.-1, J u n e 1 9 76 ; a l s o NASA CR-137923.o f f s f o r Reducing t h e Energy Consumption of Com-m e r c i a l A i r Tran s p o r ca t io n Sy s tem. Vo l . 11:Marke t and Eco no mic An a l y s i s . " Do u g las Ai r c r a f tCo., In c . , MDC-J7340-LTol.-2, Jun e 197 6; a l s o

30 . J . S t e r n , " A i r c r a f t P r o p ul s i o n - A Key

32 . J . C . Vanabkoude, "Cos t /Benef i t Trade-

NASA CR-137924.3 3. " En er gy C on s um p ti o n C h a r a c t e r i s t i c s o f

Tr ans por ts Us ing t h e Prop-Fan Concept . SummaryR ep o r t . 'I Boeing Commercial Air pl an e Co., D6-75780, Nov. 1976; a l s o NASA CR-137938.T r a n s p o r t s Using t h e Pro p-Fan Co n cep t. F i n a lRepo r t . " Bocing Commercia l Ai rp l an e Co. , D6-75780, Oct . 1976; also NASA CR-137937.

35. C . Rohrbdcii, "A R ep o r t o n t h e Aero dy -namic Design and Wind Tunnel Test o f a Prop-Fan ?lodel." AIX-2 P a p e r No. 7 6 - 6 6 ? , , \ I rL1. 'SAE1 2 t h Propulsion C o n fe rn ce , T a ! c A i c o . . Ju ly1976.

3 4. " En e rg y Co ns u mp t io n C h a r a c t e r i s t i c s o f

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3 6 . C . Rohrbach and F. B. Pletzger, "TheA I Mrop-Fan - A N ew L o o k i n P r op u l so r s ."Paper 75-1208, AIAA/SAE 11 th P ropu ls ion Con-f e r e n c e , Anaheim, S e p . 197j .

ic D e s i g n , i n d 'n 'i nd T u n n e l T e s t o f a Prop-Fan?lode1 I ' AIX\ Paper 76-667, A I A A / S A E 1 2 t h Pro-p u l s i o n C o n f e r e n c e , P a l o A l t o , J u l y 1976.T i p S pe ed P r o p e l l e r s i n Fo rw ar d F l i g h t . " A I A APaper 76-565, AIAA 3rd Aero -Acous t i cs Confe rence ,T a i o A 1 o , J u l y 1976.

39. F . B . bletzger and C . Rohrbach, "Aero-a c o u s t i c D es ig n of the Prop-Fan. ' ' AIM 7 9 - 0 6 1 0 ,AIM 5 t h A e ro - Ac o us t ic s C o n f e re n c e , S e a t t l e , Mar.1979 .&!I.. J . Swallow and R. A . A i e l l o , "RASALeui s 8- by 6-Foot Supe rso nic Wind Tunnel ."X X . 1 T?! ?:--15.2, ?lay 1 9 7 4 .

3 7 . C . Rohrbacli, "i\ Repor t o n t i l e Aerodynam-

38. D . B. Hanson, "Xear Fie ld No is e o f H igh

4 1 . R . M . Reyno lds , R. I . S a m o n d s , a n d G .C . Kenyon, "An In ve s t ig at io n of a Four-BladeS i n g l e - R o t a t i o n P r o p e l l e r i n C om b in a ti o n Wi than NACA 1-Series D-Type Cowling a t Mach NumbersUp t o 0 .83 ." NACA UU53B06, Apr. 1953.L , Chapt . V I I I , Body and Wing In te r f er en ce ."Aerodynamic Tlieory, Vol . I V , W. F . Durand,e d i t o r , B e r l i n : J u l i u s S p r in g e r, 1935.Wainauski, "Aerodynamic Doesign and PerformanceT e s t i n g of an Advanced 30 Swept , E igh t BladedP r o p e l l e r a t Mach numbers from 0 .2 t o 0.85."NASA CR - 3 0 4 7 , S e p . 1978.J e rack i , "Tone Nois e of T h r e e S u p e r s o n i c Hel ica lT i p Sp ee d P r o p e l l e r s i n a Wind Tunnel a t 0.8Mach nu mb er ." NASA TM - 7 9 0 4 6 , Dec. 1978.

4 2 . H . G l a u e r t , " A i r p l a n e P r o p e l l e r s , D i v .

4 3 . D. M. Black , R . W. Menthe, and H. S.

4 4 . J . H . D i t t m a r , B. J . Blaha, and R . J .

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0.1 M A C H C R U I SE0.8 M A C H C R U IS E- -

MIU T A R Y LONG60 r S HO RT- HA ULT iIc E NDURA NCEA I R C R A F T 7

C R U I S EL I M B &DE S CE NT DO MINA NTDO MINA TE D I I I I

-0 4ooo 8000 12 ooo 16 OOO

OPERATING RANGE, km

0 20oo 4OOo 6000 mOPERATING RANGE, n mi

F i g u r e 1. - F u e l s a v i n g t r e n d s of a d v a n c e d t u r b o p r o p( p r o p - f a n 1 p o w e re d a i r c r a f t o v e r c o m p a r a b le turbo-f a n p o w e r e d a i r c r a f t .

STAGE1 DOUGLAS LENGTH,

DC 9-30 n mi k m10r 1000 1852

R0P -FANTSFC = 0.65--A90 531

415 88 01500 2718

520 96 31000 1852

- _ _ -00 ,c3zF 4 -o 1Q= I

d Iy 2c - - -3PI- \ - - -

I/-/:A /,I * ! I I L/ 1 I0 20 30 4 0 50 60

FUEL P RICE, o i g a l l o n ( 1 9 7 3 CURRE NCY )Fiqure 2. - A d v an c e d t u r b o p r o p ( p r o p - f a n ) a i r c r a f t o p e r a t i n g c o s ts a v i n g s .

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REDUCED THICKNE SS LBLAD E SW EEP &-NACELLE BLOCKAGE 0SPINNER AREA RULING Ax-AD VAN C ED A I R F OI LS cFigure 3. - Advanced aerodynamic concepts for im -proving propeller performance.

C U R VEA

SU PPR ESS I ON OR SW EEPB D R AG D IVER GEN CE M A C H N U M BER[ N AC A 1 b S E R I E S )

C SEC T ION M AC H N U M BER W I TH 30TIP SWEEP

D EFFECTIVE SECTION M A C H NUMBER(WITH U P P R E S S I O N A N D S W EE P )

SEC T ION M A C H N U M BER , N O VELOC IT Y

1 .21- A

Figure 4. - Ef fec ts of advanced aerodyn amic concepts on bladesection Mach number distributions.

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n,,TAT'oN/-.

/' ' \

iiT IP 'R ES ULTANT AM PLITUDE{b ) ST R O N G C AN C EL L AT I O N

OF A C O U S T I C A L L Y S W E P lPROPELLER.

t+~ 00 Tiar PO O K C AN C EL L AT I O N OF U N S W t P TPI

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tiC O M P A R I S O N .

. CI R C U LA R A R C M E A N L I N E E X C E PT S R - 1W H I C H H A S a = 1.0

i20c$ 1l0I

L108:

r i3n

-uW

v)wd

T R I B U T l O N C O M P A R I S O N .

0zoP* 2of-40I2 . 3 . 4 . 5 .6 .7 . 8 .9 1.0

B L A D E R A D I U S , r l R(c ) A E R O D Y N A M I C S W E E P A N G L E C O M P A R I S O N .

F i g u r e 7. - B l a d e g e o m e t r y c h a r a c t e r i s t i c s .

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J = 3 .0 6C P = 1 . 7D = 6 2 .2 c m (24 .5 in . 1A J = 3.06, Cp = 1. 7

SWEEPB S R - 2 00D S R - l M , C - l 30"E S R - l M , A R - 2 3 00F S R- 3 49C S R - 1 30

86 -84-

- _ _ _ _ _ _ _ _ _ _ _ _ - - - - AI D E A L E FF I C I E N C Y B L A D E D R A G = 0

6 . 6 5 . 7 . 75 . b . 8 5M A C H N U M BE R , M

Figi;r? 8. - P r ed ic ! ed p e r f o r m a n c e o f 8 b l a d e d p r o p e l l e r s .

F i g u r e Q.- I r j t > ! l a ! i 3 n c f j R - 3 ;rcpeller m o d e l ir the Leu i s 8- by - 6 footw i n d t u n n f l .

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-//= 7 FLEXUREDRIVE A I R 7__, ,,_-- OAD CELLNACEL L E iPRESSL REIh lSTRL MENTED I-

W A S R EMOVEDDUSI t vG T E S T S 1 .,".

S PINNE

Figure 10. - C u t a w a y vier. o f s t r u t - m o u n t e d L e w i s propeller t e s t rig.

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0 51.90 58-50A 59. P0 60.9Q 60.400 6 1 . 9m 6 1 . 9D 6 2 . 9

r ERCENT DESIGN. 9 - ' \POWER LOADING

Lz w.9- :

4o 6 3 . 90 64.70v 51.90 54 .300 60.40

51. 954.3060.40DREF = 6 2 .2 cm (24.5 in. 1DESIGN LOADING PARAMETERC p l J 3 = 0.05933

( a ) M - 0.6.

~~2.6 3.0 3. 4 3 .8 -4.1 4 . 6 5 . 0 5 . 4A DV A NCE RA TIO , J

850 7% 650 55 0, ft lsec 1 1 0 6 6 8 m"Ap 000 f t ) ALTITUDE)

(b ) Mo - 0.8.F i g u r e 11. - B a s i c m e a s u r e d p e r f o r m a n c e fo r SR-3, 4 9 we p tp r o p e l l e r .

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82

80.

78

DREF = 6 2 . 2 cm (24.5 in. )DESIGN LOADING PARAMETERC @ J 3 = 0.05933-

PERCENT DESIG NPOWER LOADING- 0

--

-

.

.

84

t;

VLb-

z

78

I

-

82 -

80- ,+,0 ,, I

3. 6782.6 2.8 3 .0 3.2 3 . 4ADV ANCE RATIO, J

(c ) S R - l M , C - 1 . 3@ SWEEP.F i g u r e 12. - Effect o f power loading and advance r at io onne t e f f i c iency at Mac h 0.6.

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DREF = 62.2 cm ( 2 4 5 in.D E S l N LOAD I N G PAR AM ET ER88rdJ; = 0.059338 4 I82t

F 0 1>- I7 8 1

\I Iw

U (d ) SR-lM, AR -2 , 3@ SWEEP.UW 8 4 r

76 1 i-2.2 2.4 2 .6 2. 8 3.0 3.2 3.4 3.6 3.8AD VAN C E R AT IO, JleJ SR-3, AR-3. 45 0 SWEEP.

Figure 12. - C o n c l u d e d .

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DREF = 62.2 cm (24.5 in . 1DESlfN LOADING PARAMETERCplJ - 0.05933

PERCENT DESIGNPOWER LOADING

14 (a ) SR-2. AR-2. 00 SWEEP."rU-

(b l SR-1. C-1. @ SWEEP.

80

742.6 2 .8 3.0 3.2 3.4 3.6 3.8ADV ANCE RATIO, J(c) S R - I M , C-1. 300 SWEEP.

Figure 13. - Effect of power loading and advance ratioon net efficiency at Mach 0.8.

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LLI-s

i a76

SWEEP SPINNER0 SR-2 d) AREA RULED0 S R - 1 @ CONICSR-1M M" CONICfi SR-1M 3@ AREARULED0 SR-3 450 AREA RULED

J = 3.06, Cp = 1.7D = 62.2 cm (24.5 in.----------------

'L IDEAL EFFICIENCYBLADE D R A G = 0284i

80-

-

7 6 -5 7 4 -s3vl

.6 .65 . 7 . 7 5 .8 .8 5MACH UUMBER. M

Figure 14. - High speed propeller performance summary.

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PROPELLER -P O S IT IO NS 1 2 3 4 5 6

Z -27.7 -10.9 0.953 0.375 45.2 17.8 104.4 41.1 -0.15 -0.06 105.4 41.5

CENTERLINE OFTO P WA L L -

CENTERLINE OF

1 L H 2.54 1.0 10.2 4.0 , 7.62 3 . 0 3 1 . 5 1 2 . 4 9 1 . 4 36.0 91.436.0

Figure 15. - P r e s s u r e t r a n s d uc e r positions.

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,-TUNNEL/ COMPRESSOR1M- ;, ,,-PROPELLER BLADE/,l PASSAG E TONE

1101 I -L I I I 1 I I I0 1000 2000 3ooo 4000 5000 6000 7000 8000 9000 10 000FREQUENCY, Hz(TRANSDUCER POSITION 3.1

F ig u re 16. - Typ ica l compar ison of S R -3 p r o p e l l e r a tc r u i s e a n d f e a t he r .

Mo = 0.8 DESIGN CONDITIONSI

F i g u r e 17. - M e a s u r e d n o i s e c o m p a r i s o nof prope l le r mode ls .

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1 Q e o o r t M,SA 5.4 TlI- 79 '71

4 T~ l ' e nd Subtifir:W S D r l TX EL PERFORMASCE OF FOL.11 EKER GY EFFICIENTP R O P E L L E R S D E S I G S E D FOR lLACH 0 . 8 CRV'ISE

2 Government Accession N o 1 3 Reclpaent's Cata ioq No5 Report Date6. Perforning Organitatton CodeI-

9 Perfor Tipg Organ za . on Lame and AddressSation al Aeronautics and Space .AdministrationLenis Research CenterCle\e!and. Ohio 44133

1 2 Scarso. ng Agenc. Lame and AddressSatio nal .Aeronautics and Space AdministrationIVashington, D C . 30546

7 Ad!hOr sRobert J. Je ra ck i, Daniel C. SIikkelson, and Ber nar d J. Blaha

~10 W o r k Uni t No

1 1 Contract or Grant NoII13 Type of Report and Per od C o v e r e d I

Technical Memorandum14 Sponsoring Agency Code

8 Performing Organization Repor1 hro.E-9960 1

7 Key Words (Suggested by Authoris) 1Fuel conservationAdvanced turbopropPrope I e rNoise reduction

18 Distribution StatementUnclassified - unlimitedSTAR Category 02

9 %Curtly Clarslf i o f this re p u r r1Unclassified

20 Security Classif. ( o f this wgel 21 NO of Pages 22 R i c e 'L'nclassified