Impact of Advanced Propeller Technology on Aircraft/Mission Characteristics of Several General Aviation Aircraft

W A CM-167984

IMPACI OF RDVANCED PROPELLER I

TECHNOLOGY ON A I R C M F T / M I SS I ON

CHARACTER I ST I CS OF SNERAL GENERAL

A V I A T I O N AIRCRAFT

J by Ira D. Keiter McCAULEY ACCESSORY D I V I S D O N CESSNA A I R C R A F T COMPANY e.

prepared for N A T I O N A L AERONAUTICS AND SPACE A D M I N I S T R A T I O N NASA Lewie Reasarch Center Contract NAS3-21719 September, 1982 (NASA-Cd-107984) A N P A C l J r ACWANCdD N8L-33347 P k i O D X L L E R T G L L ~ ~ C L O G Y CN A A ~ L GAFT/HISSION C t t A b A C T L n I S T i C S O F S i V E k t A , cl k h k R A L A V I A l l O N ALP;HCRAPT F i r i n 1 R e p o r t (C3.i.ir.d A i r c r a t t Co.) U l l c l d s 8 . 2 p uC A 0 5 / a F A 9 1 C S C L 01A G 3 / 0 2 3 5 3 9 5

1 **I I 2 Govrrnhmt k c u l o n No, 3. R a i p k n t ' t Clu)og No.

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NASA CR--167984 5. Rrport k t r 4, T#h ond L b l ~ t l r Impact o f Advanced Propeller Technology on Sap taniber 1982 ~ i r c r a E t / ~ i s s i o n C h u r n c t e r i s t i c s o f S e v e r a l (I, rwfwminp; Orwniartim Qdr G e n e r a l A v i a t i o n A i r c r a f t .

8, hfwmltrg @goninetion llrpart No- ' 9, kr;hor(al - . d l I r n D. Keiter 10. Work Unit No, .

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Cess~a;r A i t c r a E t Company NAS3-21719 3535 McCauley nrive, V o n d a l i a , Ohio 45377 13. T y p oi Roport md hrlod bvnd

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11 S p n w ~ n ~ m y lYIm md AWrru C o n t r a c t o r Report M o t i o n o l A e r o n a u t i c s and Space A d m i n l s t r n t i o n 14, 6ponv.41~ ~gmcy b6 likrehington, D. C. 20546 503-04-7 2

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16, Supplrmntwy Notr F i n a l Heport, P r o j <.(I t Nnnclger, Clcnn A . M i t c h e l l , I'ropulsion Aerodynamics D i v i s i o n , NASA L e v i s R e s e a t c h Cen t c x , C l c v c l : ~ n d , Ohio 44135 16. Untracl S t u d i u a o f severill (:encrnl. Av:ii\ t i o n a l r c r ~ C 1 : h a v e i n d i c a t e d t l l o t t h e o p p l i c o t i o n of ndvnnccd t e c , h n o l o g i e s t o General A v i a t i o n p r o p c l l c ~ c s c a n roduce f u c , consumptian i n f u t u r e a i r c r a f t b g a s i g n i f i c n n t ; at!tount. P r o p e l l e r blntle \ i k l f i h t r c d u c t d o n e a c h i e v e d t h r o u ~ l i t h e u s e oC c o n l p o e i t a ~ , propc2l.c.r e f f i c i e n c y nnd n o i s e improvemants a c h i e v e d tlirougli t h c u s e o f ndvnncetl c o n c e p t s and Improvcd p r o p a l l c ~ r n n o l y t i c a l ctosign n ~ c r h o d s result: i n a i r c r a f t w i t h l o w e r o p e r a t i n g c o ~ t , n c q u i s i k i o n c o s t and g r o s s w e l y , l i t .

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18. Orawlbution Statrwunt tI, Ury Wad, (Sugga~td by Auhalr)) P r o p e l l e r advancad t c c l l t ~ o l o g y

U n c l a s s i f i e d - u n l i m i t e d

G e n e r a l A v i a t i o n STAR C a t e g a r y 02 Aerodynamics N o i s e C it?

11. No, of P m 20. 1Scurity Cku~f. {of chis p r ~ l 21, hicr* 18. *wiry 0091f. (01 thla rrportl U n c l a s s i f i e d U n c l a s s i f i e d d 'Fa sale by the N a f l o ~ l Technical lnlwmalron Serv~re, Spr~nglreld. V ~ r g ~ n l a 22161

PRECEDING PAGE BLANK NOT WLUED TABLE OF CONTENTS SUMMARY INTRODUCTION DESCRIPTION OF STUDY RESULTS AND DISCUSSION Technology Asschsmenr --.

Performance Considerations Acoustic Considerations Composite Material Considerations Screening of Materials Design Philosophies and Manufacturing Techniques Structural Considerations Stall Flutter Classical Flutter Avoiding Resonances Fatigue Structural Advantages of Composites Trade-offs Propeller Optimization Aircraft Mission Studi,es Technology Program Plan SUMMARY OF RESULTS APPENDICES

A - Generalized Propeller List Price Per Pound

Equation

B - Generalized Propeller Weight Equation

C - Symbols

REFERENCES iii

T h i s s t u d y e f f o r t was conducted t o g e n e r a t e i n f o r m a t i o n n e c e s s a r y f o r t h a Government t o f o r m u l a t e t h e most e f f e c t i v e t e c h n o l o g y pro- gram f o r General A v i a t i o n p r o p e l l e r s . Advanced t e c h n o l o g i e s and t h e i r a s e o c f a t e d b e n e f i t s were i d e n t i f i e d as w e l l a s t h e i r t e c h n i c a l r i s k s and r e q u i r e d r e s e a r c h progrnms.

The s t u d y began w i t h t h e s e l e c t i o n of b a s e l i n e a i r c x n f t and p r o p e l l e r s .

A p r e l i n l i n i a r y a n a l y s i s d e t e r m i n e d t h e e f f e c t o f s e l e c t e d advanced p r o p e l l e r t e c l l n n l o g i e s on p r o p e l l e r c r i t e r i a of merit, 1.e.

perforniance, w e i g h t , n o i s e and c o s t , The s t u d y of a w i d e r a n g c o f p r o p e l l e r d e s i g n v a r i a b l e 8 and advanced t e c h n o l o g i e s h a s i n d i c a t e d t h a t t h e p o t e n t i a l e x i s t s f o r p r o p e l l e r pcrforalancc! in~provcments and w e i g h t r e d u c t i o n s m e e t i n g c o n s i s t e n t l y more s t r i n g e n t r e g u l a t o r y n o i s e L e v e l s .

Advanced t e c h n o l o g y p r o p ~ ! l l c r s o f l i g h t e r w e i g h t and b e t t e r performance w i t h Lower n o i s e and g r e a t e r s a f e t y margin a r e p o s s i b l e b e c a u e e t h e b l a d e s would b e c o n s t r u c t e d from c o m p o s i t e m a t e r i a l s , S c r e e n i n g a p p r o p r i a t e m a t e r i a l s , b l a d e m a n u f a c t u r i n g techniques, and r o o t end c o n c e p t s was acroniplislled. Comments were made o n a r e a s t o b e P n v e s t i g a t e c l t o a s s u r c s t r u c t u r t ~ l i n t e g r i t y .

The 111rpact of c a e h t e c h n o l o g y cl.en~ent s t u d i e d and t h e e f f e c t o f v a r i a t i o n s o f p r o p ~ , l l e r d e s i g n p a r a m e t e r s was q u a n t i f i e d i n terms o f t h e m i s s i o n c h a r : i c t e r i s ~ l c s o f each a i r c r a f t . A t r a d e - o f f a n a l y s i s was t h e n p e r f o r ~ n c d a n "optimu~n" p r o p e l l e r d e f i n e d f o r e a c h a i r - c r a f t , The bencf its c?E t h e advanced Lechnology p r o p e l l e r s were t h e n i d e n t i f i e d r e l a t i v e t o c u r t c n t metal propellers i n t e r m s of f u e l b u r n e d , o p e r a t i n g c o s t , a c q u i s i t i o n c o s t , and a i r c r a f t g r o s s w e i g h t .

Advanced r e c h n o l o g y propellers i n c r e a s e d c r u i s e e f f i c i e n c y a b o u t 5 t o 9 p e r c e n t , lowcrcd Fuel consumption 8 t o 1 8 p e r c e n t , and reduced a i r c r a f t o p e r a t i n g c o s t 5 t o h p e r c e n t w h i l e m e e t i n g t h e FAR P a r t 36 n o i s e c o n s t r a i n t .

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'l'tre j i o n e r a l t a s k 6 purformud I n t h i s s t u d y aro s t ~ o w n i n F i g u r e 1, a n d t h e v n r l o u u s u b - c o t r t r a r c t o r s who e o n t r l b u t ~ d t o ttris crtudy and t h a i r trrerie o f uxpur t l e c tire shown 111 F i g u r e 2.

U. S. cucitonvrry u n i t s were i ~ o e d i n tlrde s t u d y . T h e e e u n i t s were c o r r v u r t e d t o t h e S ~ r t e r n u t Fonul Sye t e r ~ o f U n i t e f o r p r c e o n t a t i o n i n t l ~ f s r u p o r r .

Tlru hrrsc.linu i r i r c r t r f L s e l c c > t c > d f o r tlriti fatucfy werc c h o s e n t o b e t y p i c u l o f c u r r e n t C u ~ r e r c t l A v i a t l o ~ r (C.A.) t r i r c r a l t t y p o s a n d otrconipoes t l r t l C U L L rrrngc o f (;.A. n l r c r i l f t ~ * t ~ p k ~ i ) i l i t i u b l f ram low s p e e d , law power t o trighcr: s,pec*d, 11 t ~ l ~ c $ r power a J rc'rtrf t . Tllc scS LecCed c r l r c r u f t : i n c l u d e E o i ~ r i n tllc two 1.0 u i x l i t p l t r ~ v , t; i u g L c tinil t w i n r e c i p r o c a t i n g e n g i n c c l a s s ; 11 t w i n ~ I I ~ ~ I I I C t i ~ r t ) o l ) f o / ) p o w ~ r ~ b d ZII U C C U ~ ~ ; (111 ~ ~ r i c u l t ~ ~ r n l n p p l i - c r r t i o n s 1 1 i rc:rnf t untl ti 11inc tcb~ln ( 19) p i i s s e n g e r t u r b o p r o p c a ~ n n i u t c r u i r - c r t i f t . Tire s p c c i f ic u i r c ' r r ~ f t c%lrc~fien cis b a s t b l i n e s a r e L l l u e k r u t e d i n F l p . :I e ~ r d t h e i r pc)wc*r illid r $ r \ ~ l , ~ e ~ p e e d ~ i ~ ~ c p r ~ s e n t c d i n T n b l e 1.

The n i n e t u c n p a s s c n g c r c-urn~~~irtcr I s ~ ~ o k cln e x i s t i n g a i r c r a f t l i k e t h e o t h e r t i , b u t r a t t l e r a H t\~ciy t1l.rvri11'1 ~)rc)l)ob)ed t)y t Irt3 C e s s n a A i r c r e f t Cotnpany f o r t l r c ! Snii~ I 1 T ~ ~ . ~ ~ ~ s p o r t A i r c r i r f 1 'J'ec\hnol ogy (S'SAT) s t u d y ( r e f . 1 ) .

Ttru b n s c l i ~ r e p r o p o l 1 ctrs uocv.l l a c l r i s s tutly a r e t h e c u r s e ~ ~ t p r o d u c t i o n nrodtlls I n usen otr tbil~-h of tire s c l u t . t c t l e x i s t i n g a i r c r a f t .

F o r ttre conirnutcr r ~ i r c . r i l f t , B p r o p c l l u r wcie selected w h i c h c o u l d be d e s i g n e d Eor t h a t a i r c r a r f t, i ~ s i n g c-urrctlt G . A . p r o p e l l e r t e c h n o l o g y , T a b l c 2 p r e s u n t s ttir c l t r a r n t - t e r l u t i ~ s of u a c h b a s e l i n e p r o p e l l e r .

The t~dvsnc%ecl p r u p c l 1c.r tr?c*hno,lugics c o n s i d e r e d f o r t h e s t u d y were t h o s e wltlr t h e p o t c n t t u l f o r k s ~ p t ' o v i n ~ ~ i l r r r t r f t c h a r t i c t e r i e t i c s ; t h a t is, f u e l b u r n u d , o p e r e t i n 6 c o s t , tlc>qirieit t o n c o s t , ~ r n d g r o s s w e i g h t .

Tire s c l u c . t v d t c c h n o l u g y o l c n ~ o n t s incl l ude thost? f c l t t o h a v e any p o t e n t i d w h u t s o c v u r bt\sk*~J 011 1111 t\v111 utr t l i ) ~ ~ o f ~ * \ l r r t ~ r ~ t . p r o p e l Ler l o s s mechanisms a n d d c i i . e i e n c i e s , McCrluley c x p e r i once, r x p c r i e n c c of o t t r e r p r o p e l l e r n i i l ~ r u f u o t u r e r s , t ~ n d civrri loblc? 1 i t c r d t u r c .

I n i t , l u l l y , t h e t e c h n o l o g y t \ l e ~ i i e n t s wcrc r v c l u u t e d t n terms of t h e i r t ~ h i l . i e y t o increrrsc. p r o p < " IQr p e r f o n i i u u c e a n d / o r l o w e r n o i s e .

T h e ncwcr c o n c e p t s e v n l u u t c d wcrr NASA p r o p l r r s , blade s w e e p and a d v i ~ t r c e d t e c h n o logy u i r f o i l s . A 1 so e v c ~ l u i l t e d were improved b l a d e o u r f a c e E i n l u h e x p e c t e d fr0111 c o n ~ p o s i t c b l a d e s a n d iinprovemente i n p r o p e l l e r / n t r c e l i u t e g r e t i o n and s p i n n t : r / b l i r d e s h a n k b l e n d i q g . I n a d d i e i o n , t h e l n i t i n l e v a l u n t l u r ~ inclutltad v a r i i r t i o n s of v a r i o u s p i l o p e l l c r p u r a n ~ e t c \ r s t o u l l u w f o r t l r e l r i n c l u s i o n i n t h e t r a d e - o f f a n d o p t i m i z t r t i o n p r o c e d u r e s I n t e r i n b i l e s t u i i y .

The p r o p e l l e r elun~t?ntr: t?vnlu:itcd i n c l u d ~ \ d v a r i a t i o n s i n power

l o a d i n g (1.0. ~ t i a r n a t ~ r ) , b l a d e lotrdlng t l i t l t r l t w t i o n , ~ l c t i v i t y f a c t o r , number of Islndsti , hlecte t I \ S c k ~ i ~ ~ ~ s and t i p speed, Conrpow i t c s h kntle mittc,r irrls wt.rtl r l l ~ u k*vnluatad i n t h i a etudy.

Slncc\ rnnrposl t c? proprtl lcsr blatlcbs n r e ~ L r t r c t u r e l ly s u p e r i o r t o c u r r a n t altnninum t ) l o d c s , ndvzhnck~tl tcsctrnolofiy c l u ~ n c ~ t t r s sucll as swoap, NASA p r o p l r - t s, l o w nr3t l v l t y f t r c t n r nrrd t h i n btndo ~ e c t i o n ~ may be a n t i r e l y fetra l h l c 111 nn c ~ r l ~ z \ n c t ~ c l c t c b ~ t gri pr'~lpctl 1 e r , Suclr i l p r o p e l l o r is i 1 l u t i t r ; ~ t cltl i n I:ip~rrt\ 4 ;I l ( ~ n ) : t. ( t l , t l ~ c ~ ~ d v ~ ~ t ~ c - e t l t C C I I I ~ O I D R ~ C O I ~ C O ~ ~ B t h a t I t a i g t r t i t ~ i * o ~ * l ) r ~ l ' i ~ t v .

Coirbpus 1 ttl errtt v r l l r l ri w t > r t r sc*ri\crt~cct u t ~ t l f o u r wore s c l e c t a d f o r c * v a l u n t i o n : l : - ( ; l n ~ ~ , S - ( : ~ I I H S . Ke\v I R ~ , it11~1 Grl~ph l t e . ' I ' 1 1 0 ~ ~ W C ~ C cBvn 1 tretc\tl 111 t t~rtirr; o f s t r c ~ n ~ t l r , cqost i ~ r r t l w i d ~ : h t . Conipanlte p r o p e l let.

~ C H 1 ~ 1 1 nlibt I l o r ! ~ aritl n1rtuuf:lr 1 u r l ~ \ ~ ('cru t s wc t'c' n l s o H ~ I ~ V O Y O ~ .

A trtitlcb-of t :)nit 1 v t i 1s o f t , l r ~ p r o y c l l v r d c e i ~ 1 . r p n r f i m c t e r s was titen p e r f ur~ncbtl t o d c ~ t r ~ n i i i r r c ~ ,111 "opt lnlrra prc,lpc l lttr" f o r each a i r c r a f t ~t tid tcd. 'l'lic "opt itir~rni 1)ropc l l o r " 1 H ttro c*oa\l\lnnt i o n oE p r o p u l l c r # i z t \ * ~1~:11~:1i p:irniiii~t v r s , trnd t ~ ~ i v ~ i ~ l ~ ~ o t l I ~ ~ t ~ l ~ r i e ~ l n ~ i c ~ ~ w l ~ i c t ~ i n t t ~ a o p i ~ ~ i o n of F1cl(:;iulcy r c ~ > r i ~ r ; c ~ ~ ~ t n tilt1 most i:ti l t ;lh I ;I {,t'clpc>l l c r for ~ ' n c l l n p p l i c n t l e n .

'I'lre t uade+of f nrin lyri lr; wrrs laclr l t)t-tt~otl us i t l ~ nn n p t i n r i a a t l a n p r o c e d u r e t l m t n l lowcbtl n s t cp-wtsc\ clvltl u:rt lo11 o f otrt*t~ prolrcl l c r v n r i t ~ b l e , Tlrc c f fcr.L o f t s i l i - l r v i r r i n h li. otl i r S r c . r , ~ f l / n i t . ~ ~ i o n c l i n r n r ttlristics was ovir lu;it cjd i n t~\riiit; , I S i t s cffcactl ori p r o l ~ t ~ l l v t ' lrc~rforarnticc, t m i ~ c , s t r t r v t u r c , w i l t l \ r l : ~ l s , wc- l g \ l t , ~ n d ('otit . 'i'lrc\ nptirrrizi\t i o n 8 were carriect o i ~ t hy trs inp, n ml ss 1011 :111:r 1 y s J H I ) ~ O I ~ C ~ C ~ I I I - L ~ tililt q i ~ t r ~ i t i f l e d f u e l b u r n e d , o p c r n t in6 c * n s t , ~ ~ r q \ ~ l : q i t lo11 cxust , ant1 n l rcsrnf t G r o s s w e i g h t . T h c s e e v u l r ~ n t i o n s wcrc nmclt~ h v rc?; l zit>): t tic ill r v r n f t s o tI1~11: i m p r o v e m e ~ ~ t s i n perXorn,nnt.e ontl wc\it:llt , f o r i ~ x ; ~ r a p l ~ \ , wr,t~ld y l e l d s n m l 3 e r a i r f remcs.

ACrrrc~Et pi~vlo:ld, ralrl:tx c ~ ~ ~ d spcst~d w k b r c b trt*Ltl c n n s t o n t , F o r e a c h a l r c r n f t , tire hcvtlttf i t s 01' t l t c "1)pt 111111111 p r o l w l l t ~ r , " r c 1 1 1 t i v c t o the c u r r e n t tnctn L Cencrcrl A v i n t i o n p ~ n p i ' l l o r , wcrc r l c t c r n ~ i n e d f o r two n o i s e c o n s t r n i n t s ; f o r PAli I'rtrt 36 n o i ~ c . rclgttlnt i n n s ( o r t h e a c t u a l n o l a c I c v c l , i f l . c w . r ) , ntvl f o r I P A R l'nrt 3(1-5dB(A) , I<I:,SIII,?'S A N D 1 l T SCllSS lOlJ Pcrfornbt~ncc? C o n n i d c r n t i o n s T h c r c a r e t h r e e b a s i c l o s s mcchonisnra w h i c h a f f e c t p r o p e l l e r p e r f o r m a n c e . Thcac. o r e ltrduced ( o r i d c a l ) l o s s e s , blade d r a g l o s s @ @ , a n d i n r e r f c r c n c c l o s s e s . I n t e r f s r c n c e l o s s e s i n c l u d e a n y a d v e r s e f l o w i n t e r n c t i o n s betpreen t h e p r o p e l l e r a n d ntrrc.lle o r a i r f r a m e and a n y I n t h i s sturJy the v a r i o u s t e c h n o l o g y b e t w e e n t l ~ c h l a d c s n n a s p i n n e r .

f o r r e d u c i n g t h e s c losses and i m p r o v i n g e l e m e n t s w i t h t h e p o r c n t l t i l , p r a p e l l e r p e r f o r m a n c e w e r e i d c i i t t f . i e d and t * v n l u e t c d . These l o s s mechanisms and t h e r c f c r c n c e s u s e d t n c v n l u o t c them a r c l l a t e d i n Table

Some o f t h e s e e l e m e n t s c o u l d , w i t h u n r e s t r i c t e d a p p l i c a t i o n , d r a m a t i c a l l y inrprove p r o p e l l e r purformance, Howover, t h e uee o f any o f t h e e e e l a t r a n t s is a e n e r e l l y l i m i t e d by p r a c t i c a l c a n e t r a i n t e and t h e e l e m e n t s e f f e c t o n t h e o t h e r i m p o r t a n t c r i t e r i a of merit euch a8 n o i s e , w e i g h t , and s t r u c t u r a l i n t e g r i t y .

Tlrc e f f e c t oL t h e technology e l e a l e n t s on p r o p e l l e r performance a r e g i v e n i n F i g u r e s 5 t h r o u g h 12. F i g u r e 5 shows t h e e f f e c t o f power l o e d i n g ttritf number o f b l a d e s o n induced e f f i c i e n c y a t a t i p s p e e d of 900 Eps ( t y p i c a l of current tcchtiology) c o v e r i n g t h e 50-300 k n o t s a i r s p e e d r a n g e w i t h 2-8 and a11 i n f i n i t e nunlbcr o f b l a d e s . F i g u r e 6 shows the e f f e c t of power l o a d i n g and t i p s p e e d on induced e f f i c i e n c y , c o v e r i n g t h e same nunrber of b l a d e s and a i r s p e e d r a n g e s . Theee E i g u r e e show u c o n s i a t 2 n t t r e n d o v e r t t r e e n t lrc o p e r a t i n g range; namely, t!rat i n d u c e d c f f i c i e n c y is improved by r e d u c i n g power l o a d i n g , i n c r e a s i n g t h e number o f b l a d e s , and i n c r c a s i r r g t i p s p e e d ( r e f , 2 ) .

The c?EEicic~rry g a i n a c h i e v e d by a d d i n g p r o p e l l e r b l a d e s is d u e t o a r e d o c t i o n i n t h e t i p l.osscs ( F i g . 5). NASA p r o p l e t s ( F i g , 4) arm, a new t e c h n o l o g y cotlccpt t h a r can i l l s o be used t o r e d u c e t h i s b l a d e t i p l o s s w i t h o u t i u c u r r i n g t h e added p r o p e l l e r b l a d e w e i g h t . The amount o f t h e t i p l o s s r e d u c t i o n is a f u n c t i o n of thc3 p r o p l e t s p a n ( F i g . 7 ) .

The p r o p l e t s would b e d c s i g n e d t o o p e r a t e w i t h a r a d i a l inward f o r c e t h a t i n c l u d e s a conrponcnt i u tllc ttrrus t d i r c c t i o n t o improve e f f i c i e n c y .

T h e o r e t i c a l and e x p e r i m e n t a l work to e v u l u a t e t h e s e d e v i c e s f o r NASA is urrdilrway by Dr. J o h n S u l l l v a n of Purduc U n i v e r s i t y ( r e f . 3).

An e x ~ m p l e of r e d u c i n g tl\c p r o f i l e l o s s e s and thu8 f n c r a o s i n g e f f i c i e n c y by i n c r e a s i n g blirde sweep i s shown i n Fib. 8. For p r o p e l l e r s t h a t o p e r i t t c w i t h a s u f f i c i e n t l y h i g h t i p Mach number, t h e o u t e r p o ~ t i o n of t h e b l a d e c a n be well. i n t o d r u g rise. Sweep c a n b e u ~ e d t o r e d u c e t h e e f f e c t i v e Mach number i n rllis r e g i o n and reduce compressi- b i l i t y L o s s e s . A s w i l l bc d i s c u s s e d Litter, sweep can a l s o b e used t o r e d u c e n o i s e . The improvement i n pcrforninnce p o s s i b l e t h r o u g h t h e u s e of advanced u i r f o i l s t o improve t h e b l a d e l i f t t o d r a g r a t i o t u r n 8 o u t t o be r c l a t i v c l y s m a l l . It: i s conservatively e s t i n r a t e d t h a t a b o u t .5% e f f i c i e n c y improvement is f e a s i b l e . The e f f e c t o f r e d u c t i o n s i n b l a d e t h i c k n e s s on p c o p e l l . c r e f f i c i e n c y were s t u d i e d by u t i l i z i n g t h e McCauley S t r i p A n a l y s i s Computcr Program ( r e f . 4 , 5 ) . The r e s u l t s are p r e s e n t e d i n F i g . 9 where t h e b l a d e t h i c k n e s s r t ~ d u c t i o n s a r e shown i n t e r m s of t h i c k n e s s r a t i o r e t i u c t i o n s a t t h e 75 p e r c e n t b l a d e r a d i u s s t a t i o n . The e f f i c i e n c y &itins shnwn i n t h e f i g u r e a r e a r e s u l t of t h c l o w e r p r o f i l e d r a g of t h i n n e r b l a d e s e c t i o n s .

S u r f a c e r o u g h n e s s , e s p e c i a l l y n e a r t h e a i r f o i l l o a d i n g edge, h a s a s i g n i f i c a n t e f f e c t on d r u g c h a r a c t e r i s t i c s , i n t h a t d r a g i n c r e a s e s p r o g r e s s i v e l y w i t l i i n c r e a s i n g s u r f a c e r o u g h n e s s . S u r f a c e r o u g h n e s s h o e its most pronounced c f f e c c n t s e c ~ l o n a n g l e s o f a t t a c k n e a r s t a l l on b o t h t h e upper and l o w e r a i r f o i l s u r f a c c s . Also, r o u g h n e s s h a s its most d e g r a d i n g r f f e c t on d r u g t h e c l o s e r t o t h e l e a d i n g e d g e i t o c c u r s .

'Stre osr of c o r n p o a i t c a w l l l ~ i l low 1 ) l ~ h d t ' ~ t o lir p r o d u c e d u n i f o r m l y w i t h b e t tcsr surfncc f i n istr tllnn p i ~ s s lblc w i t 1 1 b l a d e s p r o d u c e d f r o m aluminunr f o r g i n ~ e . A l s ~ ) , t l ~ r o t r g t l t l ~ o ursu ol conlpcsi t a b l a d o m e t a r i e l s nnd l e n d i n g edge e r o s i o n s t r i p u , r n s i n t a l n a b i l i t y o f b l a d e s h a p e s and a more lc.dtSng e u r f o e c f i n i s l r i n a c r v i c e can b e r e a l i z e d . A p r o c u d u r e Eor n s e c u s i n g tlrc c f f o c t of t r l r f o i l s u r f i r c c f i n i a h o n d r a g was f o u n d f r o m rcf,,:rcnce 6.

Fro111 t h i s c c ~ f ' c r e n c c , n 1 0 % d r a g d l f f o r e n c e wea d e t e r m i n e d b e t wcc.n the' rougt\ c ~ t ~ d ~ l r l o o l l ~ u 1 r f o 11 which r e s u l t e d i n a p p r o x i m n t c l y .59: se)cyt i u n ctff i c i c * ~ ~ r ' ~ d!f fc~rcn~:c).

For a filvtln o p e r u t i n & c o n d i t i o n untl p r o p c a l l e r d i n r a c t e r , a t o t a l .

a c t i v i t y f a c t o r e x i s t s W J I L C I I I I I ~ ~ ~ I ~ ~ Z C S p r o f Lit) l o s s e s . From d a t a e x t r a c t e e l franr ref crcbnrc\ 7 , e ~ n p i ~ " i r , l l r c ? l a t l o n s t l i p s w e r e d e t e r m i n o d , c l l c r k c d o u t f o r ncc.ur,~r.v, rlnii prc1sc1ntccl j n F i g . 10, O f t e n a non- opt1111utn a r t i v l t y f n r t o r is ~lsrtl witli c u r s c n t t e c t , n o l o g y p r o p c b l l e r s t o e n t i h l c t h e u s c of tin i r v s i l i l h l c Blndc f a r g i r r g o v e r s d i a m e t e r r a n g e .

I t 1 $ il W V 11 ~ C I I L I \ J I I 1-.1~'t t ll;i t f ht' \>l't\Ht'I11'tb of il 1 ? 0 d ~ a f t o f t h e propc*l l v r i ~ f fcav tc; t1111 I low f l t * l d clntt~rir\y, t 1 ~ ) p r c r p e l l c ~ d i s k p r i m a r i l y i n t h e i ~ l h o i ~ r d st*rit i o n s . 'l'llc llil('c 1 lc\ 111. i\owl i n g and spinner c o n f i g u r - :tt i oi?s ijs",t.J on G i l i r e i 6 , i l h v i a t t o n sili-ci-t~I t t u d a y have n o t b e e n d e s i g n c d r ~ t t;Ii prnpesl lc~r/1i,rc*111 1th i ~ i t cb:~.'~t lo11 i n a l n t l . 'I't1c.y a r c dcsigt.c?d to h e miniaiunl i n s l ztl t rl hol~scl t llcl c111l:i 11c arid pr1rl)r~l l c r Ilub, hut- d o n o t h a v e uytin\\mni nl-cl;i nnd ~tri~'\iirl lnt'il slral)c>s. TI~crc%forcb, ttlc. p o t e n t i a l f o r i~nprovclllcnt: \JEIt: fti 1 t t o hc> s iglli f ic',lllt i l l l r l i t W i l A tilt\ I;UTpOBC o f t h i s s t u d y t o aJdrc's,r t l \ i $ iirc\il ant1 t o c l t r ~ l ~ l t i f y the) p o t c ~ n t lel i m p r o v e n ~ e n t s pass ill I \\ .

Scwc)r;ll ;I l rc.~-af t wi3rcx c,lro:;cw t c r c'uvclr tilcl r i ~ n j i c o f h o d y b l o c k a g e gelornet r 10s t v p l r , l l o f ( ; ~ ~ I I o I - : I ~ Avllit ioir a I r c r a f L . Tlic~sc i n c l u d e t y p l c a l ~ i l l ~ l c ool;Inl\ rcc. l l r r o c ' ; i I~ist'd l l i l t J JIIS \ ~ h l c l l h a v e hody t o p r o p e l l e r ctinnlcLer r a t i o s i n t \ \ c . I 4 t o . 5 & s:~\i):c\ : I ~ I C I t y p i c a l ;win e n g i n e ~ u r b o - p r o p i n s t a l l t a t lolls wl,lcll l ~ ; ~ v i j b l c ~ c * k , ~ g c ~ rLrt l r r s i11 tllcj . 2 3 t o - 3 8 r a n g e .

111 c ) t r l ~ r t v cictc'rnlinc\ the' Ilif lrw voLoc'i t y l l i s t r i h u t i o n , t h c 1)oul;liix-Neuma~rn P o t o n t l a 1 Flow 1'ro~:ranr (ref . 8) was u s e d a t t h e t y p i c a l cruisc v c l o c l t ict; o f c>irc+ll ,I t r c r u f t s t \ i ~ l i i $ d . S p i n n e r t ~ n d n a c e l l e o r c o w l i n g c o n t o \ ~ r s wc5rc i 3 A r ~ ~ r ~ r n l ' c i - c i ~ t i;l l l y nvc~1-,1(:~vl t n o b t t i i n n s i n g l e plnrrc~ ~ ~ r u f i l c h , Tlrc! e f i u c t : o f i n f l o w v e l a c I t y d i s l r L b u t i o n on p r o p e l l e r propulsive ef t . i c j e t w y wclu stutlicld hy i.otnpisrf~~k: t h e ilctcrnil.ned i t i f low v e l o c i t y d i s t r i b t ~ t l o ~ i w l Ch t tic i d c n l i z ~ ~ c j c ~ l s . ~ , i . c . u n i f o r n r inf.Low u s i n g Che blcCauley st r i p n n a l p s i s proprom (rclF. (4, 5 ) . T , o o k i n ~ a t t h e d i f f e r e n c e s b e t w e e n o p p u r c n t and cf f c w t i v c c ~ f f i~ i c n c irs 06 .inf J ucnced by body b l o c k a g c ~ , t h e appnrc\nt t h r u s t increases w i t h i n f l o w v c l o c i t y r e d u c t i o n s and u n r e a l i s t i c . c f f i r L c n c l ~ l s a r c c'llculntod. The t r u e e f f i c i e n c y g a i n s r e p r e s e n t o n l y a p a r t . i n ~ r o f tllu d l Cft>tcncc butwecn apparent a n d e f f e c r i v t ? c f f i c i c n c l c l s . T h e t r t r c ) r n t ~ . n t i a l p i n s a r e t h o f r e e s t r e a m e f f i c i e n e y o f t h e i s a l a t c \ c i propcd l u r p r o p c r l y twis t c d ~ n l n u s t h e ef f c r r i v c elf f i c 1cnt.y n f tiic* propel1 l v s p r n p c l r l y t w i s t e d f o r r e t a r d e d inl'low.

E f f i c i a n c y flitins from m i n l m i z k ~ t i o n o f i n t a r f a r a n c ~ lorser t h r o u g h r a d u c t i o n i n body t o p r o p o l l o r d i r r n ~ o t e r r a t i o a r o shown i n F i g . 11.

Tostfi a t Lewis Koacarch C e n t e r h t ~ v c i n d t e a t a d t h a t cha d r a g n s s o c i a t e d w i t h o round shnnk p r o p e l l e r can ba q u i t c his11 ( r e f . 9).

The h i ~ h d r a g 1s a r e s u l t o f Lwa f a c t o r s . l'h@ f i r s t f a c t o r i e t h e l a r g e i n t o r f c r e n c e drop, bl:1twec?n t h o round shank and t h e s p i n n e r s u r f a c e .

T h i a is t h e l a r g e s t porticrn o f t h e h i g h d r a g .

The etrconcl f a c t o r i s t h e dra: of t h e rountl s h a p e i t ~ c l f .

Uy n ~ a i n t a i n l n p , n r c a s o n o b l e a i r f o i l s h a p e down t o t h e s p i n n e r s ~ r f a c e , a l a r g e p a r t of t h e s e d r a g l o s s e a can be e l i m i n a t e d , Flgrirc 12 cr;trkb Lhr r c s t ~ l t i n ~ e f f i c l a n c y gallre t h a t c a n be a c h i e v c d by a e s u m i n ~ t h a t 75 p c r c c n t o f the i n t e r f e r e n c e d r a g i e e l i m i n a t e d when un a i r f o i l s h a p e r e p l a c e a t h e round s h a n k , Same earlier NACA tests on non-(;.A. p r o p e l l e r s (r4.f. 1 0 and 1 1 ) trilve shown l a r g e p o t e n t i a l c f f i c l c n c y g a i n s by -improving ttw b l n d c geometry i n t h e i n b o a r d r e g i o n . C o r r e l a t i o n o f tileso r c l ~ u l t s w i t h at):plrical l o s s e s l & i m a t o s t ~ n d t h e a f o r e n ~ e n t i o n c d wind t u n n c l t c 4 t x i s r e p o r t e d ~ I I r e f e r e n c e 9. F u t u r e work t o h c t t e r i n t c l f f r a t e t h e epltlner n r ~ d b l a d e s may o f f c l r some a d d i t i o n a l imp rovemcn t s .

A p a r a m e t r i c s t u d y was c o n d u c t i ~ d t o e v a l u a t e t h e c f f e c t s o f e a c h of t h e above t e c h n o l o g y e l c i ~ i e r r t s ( T a b l e 3 ) on p r o p e l l e i ' performance f o r e a c h of t h e e i x s t u d y a i r c r a f t . Thesc r c s u l t s were uscd I n the t r a d e - o f f and p r o p c ? l l c r o l ) t l a ~ l z a t i o n d l s c u s s i ~ c l l a t c r .

Acous t i c C o n r ; i t l u r i ~ t i o n s The prirnary t e c h n o logy e l c a c n t s a l f c c t inl; acouu2;ics a r e number o f b l a d o s , t i p s p e e d , thicknc5ss r o t i o , a c t i v i t y f a c t o r , sweep, b l a d e l o a d i n g , a i r f o i l t e c h n o l o g y l e v e l , ond p r o p l u t x .

A list of t h c s ~ tc~~hno1r1f:y c l a n ~ e n t s tilong w i t h t h e r e f e r e n c e s u t i l i z e d t o e v a l u a t e t l ~ c i r c C f e c t a11 propcllcar c r i t e r i a o f merit are shown i n T a b l e 4 .

Ex~amplcs of tilt. c.ffccts o f some of t h c a h o v t ~ tec'tinology e l e m e n t s on n o i s e a r e prcsc1ltt.d i n I2,i#urtls 1 3 t h r o u g h 1 7 and 19. The f i r s t t h r e e examples, F i g u r c s 13-15, show ttlc cdffec't o f t h r e e clenbenta ( b l a d e number, b l a d e sweep, arid b l a c k th3cknesci) t h a t havo t h e p o t e n t i a l t o d a c r e a a e n o i s e a s w e l l a s i n c r c n s c performance ( F i g u r e s 5 , 6 , 8 and 9). I n c r e a s i n g doctcnsc! t h e l o a d i n g p e r b l a d e and concomitantly t h e number of h l a d e s w i l l t h e b l a d e l o a d i n g n o i s e . Swccp can r e d u c e propeller n o i s e t h r o u g h p a r t i a l c a n c e l l a t i o n o f t h e a c c w s t i c p r e s s u r e s i g n a t u r e emanating from t h e d i f f e r e n t b l a d c r e c l i a l l o c a t i o n s ( r e f . 1 2 ) . T h i c k n e s s n o i s e r e d u c t i o n s a r e l i m i t e d by o s t r u c t u r n l c a n s t r a i n t on t h e a c h i e v a b l e minimum b l a d e t h i c k n e s s , O t h e r t e c h n o l o ~ y r l c m e t ~ t s , such a s r e d u c i n g t h e t i p speed ( F i g , 1 6 ) and movinfi ~ h c peak luadink: inhoord ( F i t : . 17) w i l l d e c r e a s e n o i s c , b u t

a t ths oxponuo of lowor perf ormrmnco .

I'orfotmirncc, t r ~ * . ? : k l t i e s raoul t ing from r ~ d u c a d t i p spcaed ntrtl tnovlng peak l u o d i ~ ~ g irrh,skrd ;rr@ drown i n Figs. 6 a~rd 18, rmpcc t ivoly ' Activity factor rrductiot\s I\nvo a d i r e c t impact c m !oworing thick- rrcse nolsc;. Tho cffuct c)n ovcrall sound prsasuro l e v e l i r as indicated Ln Fig, 19. Art i v l t y f r ~ c t o r rc*quirc~msnts nrcl pr'lmdrlly d i c t a t e d by pcrforrnclnce. If rodtrcsd r ~ c r i v i t y f a c t o r i a noodod for parformonce optimixitrg thon tiuieQ i e a l s o rcducvd, but i f tlrc o p p ~ s i t c is t r u e then the noise tlnd pcrfornrancc rcquirt*eCl,ts a r c i n c o t i f l i c t .

Bucnr~sc o f the I,igtr relirtive veLocity a t tho t i p , NASA proplcate w i l l have t o be ce:*eful ly intagrntcld l n t o the bled@ acoustic deaigtr t o korp the noise fro.? jtrcretrelng. Hv swccl~lnp, the proplets r o l s t i v a t c r tho r c e t u f the bl&\Jea, bton~c* naiwc c*ar~ccllltrly should ba poeeible, I n lac t, eoale 1111 t in1 acousl; ice t t t ~ i ~ l y ~ i e work Ira8 Sndicat ,*d Stlet swapt propletd ran b e dcr;ipncd without nn inrressc i n o v e r a l l propellc*r noise ( r e f . 3 ) . Noise* rutluctio~r t h r u u ~ l r lncorpori~tion of proplate is cat~scrvrrt tvcly pstlnintc~tl t o ilrc*ott~lt f o r n h c r t ~ l . 5 d B ( A ) .

1 , i t t l e 1s kni>ut~ rei.,ari!ii\i; A !~i: patr'titttil redrjctions pasaibie through the u s e of rrdvauc-ed s t r f o i l s . Ehroei experts ngroe t h a t &r small p o t e n t i a l c x l e t s . About . 5 dB(A) i s tht) t j c f ~ t . ct~timlrte cslrrerltly nvailabla.

i \ p;~rariiet r l c ac\~dy o f t l1t1 .rl~ovo ;1co\18 t i~b c* letnents was cotrtlucted t o o\)tnin di1t.o for t l r v t radc\-off arid propel l c r opt lnrizotion procedures.

'I'hc of fcbi't o f c l ~ c . l ~ ircoust i e t c\r*litrol(\g~ el vmcnt ot\ p1-opci l e r truiec. wils c - ~ a ) x a t ~ t d f o r ; ivtr rc3rLif t cover it]): ir w CJcj power range n u rcprcscntu- clvo of tire Cc%nerrrl Aviot ton flc~cbt . 'I'trc* four ttircrnft were tile ( : ~ ~ I B I I ~ 1 7 2 N , Ccss~rn 210M, Ccsencr 414A irttd tlri- 19 prlsaengcr commuter a i r c r a f t .

'I'll!,? C~usenu A18813 witti not inc%Judcad i n tlir pi~ri~mcltrlc ~ t t i d v s i n c e agricuLtur111 a i r c r n f t arc1 not b ~ ~ u ~ r t l by I:hH i'trrt 3 0 . Also, the Ccsstrn 4 i 4 A a i r c r a f t was not i n c l udcd due t o ftlntling nvrri lilbil i t y , howcvc-r, tile crcoustfc11 e r r i s i t t v i t y of the t c~c*htiali,gv c>lcn~onts wns irrfcrri~ti from s l m l l t r r i t i c ~ t o tlw \ ~ t \ w r n ir4rr:1f t st utl lcd.

JCn artier t o ro2iohl y meet t l l t l f u t u r r perforn~unc*e and a c o t ~ s t l c rcquirenlc~~ts o f G . A . ~ , r o p ~ l l c r t ; , corrsidcr;~t i n n st~nuld t ~ c fiivetr t o blades that a r c fnhricntr.ci i r u n ~ ndvnncoit c o n i ~ c ~ s i t c ~ nir~toritrl:s. Suclr bledcs may provide n considcrab lv 1 owcar prnljcll lc\r we i ~ 1 1 t ,ind ncibwcr fnhricut lnrr trrhniqucs may lower thcair c o s t s rrt a lovcil t l \ u t w i l l make t h e i r p r i c e s Advnnr.cd P ilr~nientary competitive w i t h rhnse n f ,r lurrrintim h l ndra.

con~posi t c mnterinls coah lnc low dii11s.i t ics i~nd law notch ec\rrsitivi ey with high s t r e n ~ t h s i111ti st 1 f f n r % s s c v i . l'h~i:;c 1 - h a r a c t c r t s t i c s may icad t o prupellc~rs having n o t o r l l v 1 ll:llti>r w c ~ l ~ l i t but hct t c r pc.rforninnce, lower noise and g r e a t e r scrfcity margins (17it:. 20). Thc trerforniatrcc sild rroisr

b e n e f i t s r e s u l t from a w t d a d e s i g n flexibility which allows c o n t r o l o f t h i c k n a o s , mane, and a e , ' i n e s s d i s t r i b u t i o n t o a d e g r e e n o t ponrible w i t h m e t a l b l a d a s . T a i l o r i n g o f t h e compoeito m a t r i x w i l l n l l o w t h e d e s i g n e r t o v a r y t h e r a d i a l s t i f f n e s s d i s t r i b u t i o n and s h a p e t h e p r j m a r y b e n d i n g and t o r s i o n a l mode^ t o t h e d e s i g n requirements. Thuu, t h e dynamic and e t r a n g t h c h a r a c t e r i e t i c a can b e o p t i m i z e d t o n l l o w t h e c o n s t r u c t i o n o f b l a d e s w l t h advanced d e s i g n c o n c e p t s ; f o r example, a t h i n n e r , l o w e r a c t i v i t y f a c t o r , swept b l a d a w i t h p r o p l e t s s u c h as s k e t c h e d i n F i g u r e 4 .

Because f i l a m e n t a r y m a t e r i a l s a r e o n l y s t r o n g I n t h e f i l a m e n t d i r e c t i o n , c a r e f u l c o n s i d e r a t i o n must be g i v e n t o p l y o r i e n t a t i o n and p o s s i b l y t h e u s e o f h y b r i d i z e d m a t e r i a l s t o meet t h e d e s i g n r e q u i r e m e n t s .

The h i g h e r b l a d e d e f l e c t i o n s r e s u l t i n g from t h e u s a o f c o m p o s i t e m a t e r i a l s r a t h e r t h a n atuminum must bc c a r e f u l l y a n a l y z e d i n t h a t t h e y can l e a d t o l a r g e o u t o f p l a n e deflections and may r e s u l t i n a e r o e l a s t i c i n s t o b i l i t i c s .

S c r e e n i n g of Matoria&. - I n the p r e s e n t s t u d y a r a n g e o f c o m p o s i t e m a t e r i a l s were s c r e e n e d t o d e t e r m i n e t h e most d e s i r a b l e c o n c e p t s f o r advanced propellers. The r e s u l t s p o i n t e d t o a f a m i l y of m a t e r i a l s i n c l u d i n g E-Glass, S-Class, Kuvlnr and G r a p h i t e . Theae m a t e r i a l s a r e compared i n F i g u r e 2 1 i n terms o f t h e w e i g h t and c o s t o f a c o m p o s i t e The m a t e r i a l s p r o p e l l e r b l a d e r c l i t t i v e t o nn aluminum p r o p e l l e r b l a d e .

shown i n t h e E i g u r c a r e a r r a n g e d s o t h a t c o s t i n c r e a s e s and w e i g h t N o t i c e t h a t t h e m a n u f a c t u r i n g c o s t s o f d e c r e a s e s from l e f t t o r i g h t .

t h e c o m p o s i t e b l a d c s ))re a l l a b o u t t h e same oo t h a t t h e t o t a l c o s t Although v a r i a t i o n s a t e p r i m a r i l y d u e t o t h e changes i n m a t e r i a l c o s t s .

t h e m a n u f a c t u r i n a c o s t s of t h e composite b l a d e s a r e h i g h o r t h a n t h o s e of aluminum b l a d c s , t l ~ c t o t a l m a t c r i n l c o s t s a r e lower i n many c a s e s b e c a u s e t h o 50w r n o t e r i n l w e i g h t o f c o m p o s i t e s morc t h a n o f f s e t s t h e Ttlc t o t a l c o s t of t h r e e of t h e c o m p o s i t e b l a d e s t ~ t g h e r c o s t ker pound.

(E-Glass, S-Glass, and K e v l a r ) a r c n e a r l y c u m p e t i t i v e w i t h t h e c o s t o f aluminum b l a d e s and f u t u r e improvements i n f a b r i c a t i o n t e c h n i q u e s c o u l d make them even morc c o m p e t i t i v e .

The b e s t m a t e r i a l c h o i c e f o r t h c n e a r term u s e o f c o m p o s i t e b l a d e s a p p e a r s t o b e &-Glass (weighing 73 p e r c c n t of a n aluminum b l a d e and c o s t i n g 20 p e r c e n t more) and K e v l a r (weighing 50 p e r c e n t and c o s t i n g 30 p e r c e n t m o r e ) , I t i s o b v i o u s from t h e h i g h c o s t of G r a p h i t e t h a t i t would o n l y b c used when a b s o l u t e l y n e c e s s a r y t o meet h i g h s t r e n g t h n e e d s i n advanced p r o p e l l e r s . A h y b r l d i z e d c o m p o s i t e i n c l u d i n g small amounts of g r a p h i t e would be more f e a s i b l e under most c i r c u m s t a n c e s , Design P h i l o s o p h i e s and M a n u f a c t u r i n g T e c h n i q u e s . - The p r o c e d u r e u s e d t o d e s i g n a p r o p e l l e r i n v o l v e s a complex i t e r a t i o n p r o c e s s t h a t a t t e m p t s t o o b t a i n t h e l o w e s t c o s t p r o p e l l e r b l a d e which s a t i s f i e s t h e T h e s e c r i t e r i a aerodynamic, s t r u c t u r a l and e n v i r o n m e n t a l c r i t e r i a .

a r e l i s t e d i n F i g u r e 2 2 and t h e 5 t o r a t i v e p r o c e s s t o a s s u r e b l a d e Aerodynamic and e n v i r o n - s t r u c t u r a l adequacy i s shown i n P i g u r e 23.

m e n t a l c r i t e r i a i n v a r i a b l y c o m p l i c a t e s a t i s f y i n g t h e s t r ~ ~ c t u r a l and

m a n u f a c t u r i n g c o s t c r i t e r l s . For t h a mofit p a r t , i t is t h e d e t a i l e d t r a d e - o f f a between a r r u c t u r a l e f f i c i e n c y and m a n u f a c t u r i n g ,oet t h a t d o ~ n i n t r t s tlm m a j o r a n g l ~ i u c r lnp, c f f o r t .

Cost o f m a n u f a c t u r i n g i n c l u d a e q u a l i t y r i e k f a c t o r e o s s o c l n t f i d w i t h t h e m a n u f a c t u r i n g p r o c e s r s e l e c t u d , The r e e u l t s o f a s t u d y o f c o m p o s i t e m u n u f a c t u r i n g t a c h n i q u a s t h a t a r e a p p l i c a b l e t o p r o p v l l e r h l a d e c o n s t r u c t i o n a r a d e s c r i b e d below.

Elethods of lend f IIR ildp,c3 i ' r o s i o n p r o t c t t t i o n , v a r i o r ~ s forms o f composite m a t u r i r ~ l c e t ~ s t r u c * t lon and tf l F f c r c n t corlrelrts o f h l a d e hub r e t e n t i o n a r e p r e s e n t e d . The a d v a n t a g e s nnd d i s e d v u n t n g e s of anch method a r e d i s c u s s e d t o i n d i c a t e t h e r e l a t i v c m e r i t s of cnch method and show where advances i n t h e s e mcl)thods may bc ncedcd For t h e i r s u c c c a s f u l a p p l l c a t i o n t o b l a d e c o n s t r u r t . i o n .

Crfbslon p r o t e c t i o n on conrposito b l a d e s can be p r o v i d a d by a n c l c c t r o f ormcd n i c k e l or H t n l n l c s s tool cap. Because of t h e compound c u r v a t u r e of ndvencotl h l a d e c a n f igrrrat i o n s , t ~ o w c v e r , a n e r o s i o n cap might have t o be of e l e c t r o f n r m e d n i c k e l . T l ~ c l e e d i n g e d g e r a d i u s , t w i s t and plonform mnv p r e c l u d e tlrc u s e o f simpler s t a i n l e s s steel c a p s .

Composite b l a d e f n h r i c n t i o n can ba c11.ns8if i c d a c c o r d i n g t o t h e m a t e r i a l form u s e d i n r h c p r o c e s s . T h r c c major categories a r e f i l a m e n t winding, woven f n b r i c ~ and t a p e jioods.

F i l a m e n t w i n d l r ~ ~ was e x o n ~ i n ~ d i1S a f a b r i c a t i o n t e c h n i q u e . T h i e t e c h n i q u e was d j s c a r d e d b e c a u s e t h c t e c h n o l o g y o f t h i s p r o c e s s is i n c a p a b l e of p r o d u c i n g t h c b l a d e s c l c t i o n s which have v e r y s m a l l l e a d i n g and t r a i l i n g e d g e r a d i i .

Woven E ~ b r i e s were c o n s i d e r e d i n a broad s e n s e , b u t t h e y were e l i m i n a t e d f o r s t r u c t u r a l r c a s o n s . Woven f o h r i c s o f a g i v e n m a t e r i a l a r e l o w e r i n modulus and s t r e n g t h compared t o t a p e goods. OK a n e q u i v a l e n t s t i f f n e s s b a s i s t h i s r e s u l t s i n a w e i g h t p e n a l t y f o r woven f a b r i c s . Based o n t h e s e f a c t s , t h i s m a t e r i a l form i s n o t crdmpetltive w i t h t a p e goods f o r a minimum w e i g h t b l a d e d e s i g n .

The m a n u f a c t u r i n g p r o c e s s e s a d d r e s s e d i n t h i s s e c t i o n assume t h e u s e o f t a p e goods i n t h e form o f p r e p r c g m a t e r i a l s . Each p r o c e s s is d e s c r i b e d below a l o n g w i t h a summary o f t h e a d v a n t a g e s and d i s a d v a n t a g e s of e a c h .

A c o n c e p t u s i n g p r e c u r e d l e a d i n g and t r a i l l n g h a l v e s is shown i n F i g u r e 2 4 . The b l a d c i s hollow and molder! i n two h a l v e s w i t h t h e s p l i t l i n e a t t h e c r o s s p l y o v e r l a p which is on t h e p i t c h a x i s . T h i s o v e r l a p l o c a t i o n h a s two a d v a n t a g e s . F i r s t , i t is a t t h e maximum s e c t i o n t h i c k n e s s , which maximizes i t 6 c o n t r i b u t i n n t o t h e f l a p w i s e s t i f f n e s s . Second, t h e w e r l a p c o n t r i b u t e s t h e l o w e s t i n c r e a s e i n p o l a r moment of i n e r t i a . Due t o t h e s ~ n a l l e r l e a d i n g and t r a i l i n g e d g e r a d i i of some advanced a i r f o i l s , a p r e c u r e d c a p i s r e q u i r e d a l o n g t h e

e n t i r e t r a i l i n g e d g e and s e c t i o n s of t h e l e n d i n g edge which are w i t h o u t a n e r o s i o n cap.

The p r e c u r e d c a p is i n s e r t e d o v e r t h e uncured l a y u p .

The c u r e of a s p e c i f i c h a l f bonds t h e c a p i n p l a c e .

Once t h e h a l v e s are c u r e d , 8 p r a c u r e d web is bonded t o t h e t r a i l i n g edge h a l f . The web acts as a mandrel when bonding t h e halveti t o g e t h e r , s o t h a t t h e bond c a n be p r e s s u r i z e d . The two h a l v e s are t h e n bonded t o g e t h e r o v e r t h e r o o t end r e t e n t i o n f i t t i n g . The r o o t end is f i l a m e n t wound and t h e l e a d i n g edge e r o s i o n c a p i s bonded t o t h e c u r e d b l a d e .

The a d v a n t a g e s o f t h i s m a n u f a c t u r i n g method a r e : I) t h e r i s k of f i b e r w r i n k l e s is low b e c a u s e a l l t h e s u r f a c e s are molded i n matched d i e s ; 2) t h e placement of t h e f i b e r s is a c c u r a t e ; 3) e x c e s s r e s i n is removed a s s u r i n g a n optimum f i b e r volume; 4) t h e c u r e d p a r t s c a n b e i n s p e c t e d b e f o r e f i n a l a s s e n b l y r e s u l t i n g i n low t o t a l b l a d e s c r a p p a g e .

The d i s a d v a n t a g e s of t h i o p r o c e s s a r e t h a t : 1 ) t h e p r e s e n c e of t h e s p l i t l i n e s r e p r e s e n t a n added c o s t b e c a u s e d r e s s i n g i s r e q u i r e d a f t e r f i n a l assembly; 2 ) s e c o n d a r y bonds o f p r i m a r y s t r u c t u r e i n c r e a s e s l a b o r man h o u r s ; 3) bonding t h e e r o s i o n c a p a s a s e c o n d a r y o p e r a t i o n a l s o i n c r e a s e s t h e l a b o r man h o u r s ; and 4 ) s o l i d t i p s e c t i o n s add c o m p l e x i t y t o t h e t o o l i n g and m a t e r i a l l a y u p o p e r a t i o n s .

The second c o n c e p t i n v e s t i g a t e d i.nvolves p r e p r e g m a t e r ? a l l a i d up around a p r e c u r e d u r e t h a n e foam c o r e and is p r e s e n t e d i n Fkgure 25.

T h i s method h a s one m a j o r c u r i n g o p e r a t i o n . The l e a d i n g and t r a i l i n g edge p r e c u r e d c k p s a r e t h e n p r o p e r l y l o c a t e d and t h e assembly is c u r e d .

The o r o s i o n c:qv i s bonded t o t h e cured b l a d e and t h e f i l a m e n t , winding i s a p p l i e d t o he r o o t end i n s e c o n d a r y o p e r a t i o n s . I n t h i s p r o c e s s t h e foam c o r e must b e s k i n n e d t o p r o v i d e a d e q u a t e l e a d i n g and t r a i l i n g e d g e p r e s s u r e d u r l n g t h e c u r e c y c l e .

The s i g v i f i c a n t a d v a n t a g e of t h i s p r o c e s s i s t h a t t h e :e is o n l y o n e major c u r i n g o p e r a t i o n . Secondary a d v a n t a g e s i n c l u d e t h e a b s e n c e of primary s t r u c t u r a l bonds and d r e s s i n g of sny s p l i t l i n e s .

The d i s a d v a n t a g e s a r e numerous. T h e r e is a g r e a t e r r i s k of f i b e r w r i n k l e s and f i b e r wash w i t h t h i s p r o c e s s . More hand work o f t h e pre- p r e g m a t e r i a l i s r e q u i r e d t o minimize t h i s r i s k . I f d e f e c t s do o c c u r , f i n a l i n s p e c t i o n i s more c o s t l y . The c o s t o f t h e m a t e r i a l s and l a b o r is s i g n i f i c a n t , i f all e s s e n t i a l l y completed b l a d e is s c r a p p e d . When t h e r o o t cnd mandrel 18 molded i n p l a c e , a d d i t i o n a l t o o l i n g t o p r e s s u r i z e t h e c o m p o s i t e is r e q u i r e d between t h e foam c o r e and mandrel.

T h i s p r o c e s s r e s u 1 . t ~ i n t h e h i g h e s t b l a d e we:ght of t h e t h r e e c o n c e p t s p r i m a r i l y b e c s u s e of t h e foam c o r e w e i g h t . H i g h e r c u r e d r e s i n c o n t e n t is i n h e r e c t w i t h t h i s method. T h i s a l s o c o n t r i b u t e 8 t o t h e i n c r e a s e d w e i g h t . In t h e t i p r e g i o n where t h e b l a d e s e c t i o n s a r e t h i n , t h e s e c t i o n s must b e s o l i d composite f o r s t r u c t u r a l i n t e g r i t y . Because

o f t i r i a r u c ~ u i r e m e n t F t l w r w r i n k l u s and f i l l e r wrrelr itre a d i s t i n c t p o s e i b f i l l t y . Since t l i c r c l t i no forrn~ i n t h o s a l o c a t i o n s i t i e d i f f i c u l t t o a c c i ~ r n t c l y l o c a t e t h i > ~ n n l c r i n I .

'Sha t h i r d 1~ropoclc.d cloticopt. u s c e p r o c u r e d o ~ p p c r and l o w e r Rpara, p r a a a n t u c l i n F i g u r e 2 6 . Thu u p p u r and l o w u r r ~ n i < l i r o c t i o n n l a p n r e are e e p n r a t u l y precurccl on n c r o s ~ p l y s k i n c a r r i e r i n matched d i e t o o l i n g .

Once c u r u d , tlrc s p n r e are bonded t o j i c t h e r , n l o n ~ w i t 1 1 t h e r o a t end m n n d r o l , f o r n ~ l n g nn a i r t i n h r I n n e r chatnhcr, 'I'lle o u t e r s k i n i e t h e n d r a p e d o v e r t h i s up:ir o v t l r l a p p l n g tit: t h e p i t c h rrxis. The p r o c u r e d I c u d t n g und t r e i l t n ~ cvlgv riil)8 rtad c-rotlion u ~ r i p u r e n l s o p o e i t i o n a d a t t h i s t.inie, 'l'hc e n t irc! newrmhlv 1s t h e n 1)lnccd i n t h e a s s e n ~ b l y t o o l , The i ~ r t c r n n l c a v i t y is p r t w i t ~ t - i ZC'LI t~tid ~ I I C s t r i t c t t l r o i s c u r e d . A f t a r the, c u r e c y c l e , the* f l a s h 3s rcmavctl rrntl rllc r o o t end is F i l a m e n t wound.

'l'lrc n d v a n t np,c?e of tlril prtac~urctl 1t.nti i n g iind trtr f l in& h a l f c o n c e p t a r c r r l ~ o t ~ p p l i c n h l ~ t o rliitl e ~ c t t i a d . A d t l i t l o n n l o n e s urc: 1) t h i s p r o c e s s pratlttcee t l ~ c ! 1I~litc*r;t: compost t c s t r u r t u r c ; 2) no d r e s s i t l g o f t h e s p l i t l i n e s i e r c q u i r c d ; 3) t h c secondoxy bondinp, o f t h e e r o s i o n c a p l a e l i m t n a t c d ; and 4 ) sol i d t l p e e c t i a n s causie no s t g n i f l . c a n t p r o b l e m s .

l'nc! c 1 L ~ a d v a t i t n ~ ~ ~ ~ s rircl t l)n t t l r i s proccwfi r e q u i r a e a two s t e p c u r i n g proccrdurc! and spl 1 t 1 l,nc\s 011 t IN> ~ ) ~ ~ ~ ~ ~ t i r t ~ l ti'ir)llr Iinlvce tiiay r c t q u i r c s p e e i u l trimn~ning.

'I'his c.im(*Cpt ~1131)~iirs t o 1)s rlrcl milst promi s i n g p i n c c 3 t seems t o h a v e more advantagcfi ntid ft.bwer d i s n d v a n t a f l c s t h a n tllc o t l i e r two c o n c e p t s .

'l'llrec d l f ' f e r e n t r o o t cvid ccinc9apt s wt3re $11 ud i c d . A c t e s c r i p t i o r r of e a c h c o n c e p t is cc711taincd I)utow nloni\ wi t l l n uumnrcrry of t h c a d v a n t a g e s a n d d l s n d v n n t u g c s o f ~ i t ( ~ i l .

The f i r s t rcinccpt shown i n lpigure 2 7 rchprcsonts n s t a n d n r d twke b o t t l e r c t e r i t i o t ~ c o n c a p t . ?'he b l n d a root cntl f t h c r s wrap a r o u n d n A f t c \ r s u f f i ( - l e n t ncclcing, ttils nlfindrel e p h c r l c a l i n n e r m e t a l s \ i ~ n t l r c l .

reverses und i t i c r c l a s e s i n d lt1111ct c r . 'I'I\c* rccltrc'cacl c.ross-sor t j o n 1s then O n r ~ (*iired Llie windinp, f i l a n ~ e n t wound wit11 S - ( ; l i l s ~ R I I C ~ ~ p o x y r e s i n .

is n~ochinccl L O n t o p e r . An nlunrintun crutc*r s l c ~ v c l i~ bondcd o v e r t h c f i l n m e n t wind inp,. Tlrc .Inner rn&ntlrr\ 1 ,is pc?sI t Loncd r r l a t i v e t o tlie o u t e r a l e e v e w l t h a t'l\ru hol t., Olrc1i\ t hc? bond i s c u r 4 , clie holt: i s t h e ;Ivtirny,ct r c l n t r l fSril\,il f u r c r * v n l \ ~ e .

p t e l o r r d e d t o I ) t h e r e t e n t i a n 'I'lia a d v i t n t n g c ~ a ol* tlro rokc- h o t t l c rouctlpt arc?: 2) n m c t n l I n t e r f a c e between l a a p r o v e n cic\sly,n f o r coml>n?;itta I>lr~tic,.i; t h e b l a d e and Irtih f e c i I i t i ~ t c s sclnl i n ~ t h i ~ lul?r i c n n t i n t h e p+Ltcli b e a r i n g ; a n d 3) t h e m e r n l l l r I ~ i t e r f t ~ c c \ ; i l s o ; ~ l towe nt tnchrrrent of counterwed g l i t s , s n a p r i n g , rind cxtcrntal propc. 1 1 (!r Ilil lnnrcr wcJghts.

The d i e a d v a n t a g a s of t h i s r e t e n t i c i n n r o : 1 ) t h o machining c o s t s a r e r o l a t i v c l l y h i g h ; 2) i t is r e l a t i v o l y heavy w i t h two metal p a r t 8 and t h e b o l t hardware; and 3) i n d i v i d u a l , i n t e r n n l b l a d e bal.oncing 'ie d i f f i c u l t .

The second c o n c e p t slrown i n F i g u r e 28 u t i l i z e a a n i t r t s r n a l mandrel e i m i l a r t o t h o coke b o t t l e , b u t a l l t h e b l a d c l o a d s a r e t r c n e m l t t e d t o t h o mandrel. T h t s e l i m i n a t e s t h e need f o r t h e m e t a l e l e e v e . The f i l a m o n t windirrg, d u e t o its s m a l l c r o s s s e c t i o n , r e q u i r e s a l u r g e m a t o r i a l modulus s u g g e s t i n g g r a p h i t e f i b e r s . The p r a l o a d on t h e mandrel is p r o v i d e d by t h a f i b e r t e n s i o n d u r i n g t h c f i l a m e n t winding o p e r a t i o n .

The a d v a n t a g a s o f t h l s r e t e n t i o n o r e : 1 ) t h e f i b e r o r i e n t a t i o n i e ueod i n a n optimum manner compt~red t o t h e o t h e r concepthe; 2 ) tIre weight is reduced compared t o t h e coke bottiqz retention; 3) t h e r e is o n l y one m e t a l p a r t t h a t needs machining; and 4) i n d i v i d u a l i n t e r n a l b l a d e b a l a n c i n g is c n s i e u .

The d i s a d v u n t a g e s o r e t h a t t h e f i b e r s ond r c s i n a r c exposed t o t h e p i t c h b o a r i n g l u b r i c a n t ; t h e e x t e r n a l p r o p o l l c r b a l a n c e w e i g h t h o l e s r e q u i r e t h r e a d e d i n s e r t s ; t h e s n a p r i n g is bearing i n t h e coniposite m a t e r i a l ; a r ~ d a nlore expclreive countczrweight is r e q u i r e d i f t h e w e i g h t i s clamped, o r l o n g e r b o l t s rlrc r e q u i r e d i f tho. w e i g h t is b o l t a d t o t h e i n n e r mandrel.

The t h d r d c o n f i g u r a t i o n u t i l i z c s a l l c o m p o s i t e m a t e r i a l s i n t h e c o n s t r u c t i o n . A s slrown i n F i g u r e 23, t h e composite m a t e r i a l s t r a n s i t i o n o v e r a c o m p o s i t c mandrel and ttlrnlinate i n b o a r d of t h e p i t c h b e a r i n g groove. T h i s t e r m i n a t i o n o f thc. f t b e r s c a u s c s j n r e r l a m i n a r s h e a r s t r e s s e s and b e a r i n g s t r e s s e s i n t h e compositc a s t h e l o a d s a r c t r a n s - f e r r e d t o t h e s p l i t r i n g of tire p i t c h b e a r i n & . The i n t e r n a l mandrel.

r o n c t s t o t h e hoop l o a d s and i s a c a v i t y f o r t h e i n t e r n a l b l a d c b a l a n c e w c i g h t s . The f i l a m e n t winding p ~ r f o r r n s t h c same! f u n c t i o n s a s t h o s e d o s c r i b e d f a r t h e h y b r i d c o n c e p t .

The a d v a n t a g e s of t h i a c o n c c p t a r e t h a t i t Is t h e l i g h t e s t w e i g h t of t h e t h r e e c o n c e p t s ; rile p o t e n t i c l l e x i s t s f o r no machining of m e t a l l i c p a r t s ; and the i n d i v i d u a l i n t e r n a l b l a d e b a l a r c i n g is e a s i e r .

Thc major d i a a d v a n t a ~ e i s t h a t t h e f e a 6 i b i l l t y of t h i s c o n c e p t The o t h o r i s h i g h l y dependent on t h e hub c o n f j g u r a t i o n and geometry, t h c f'ilumcne winding and t h e y itre t h e same a s d i s a a ~ ~ n n t n g c s r e l a t e t o those, d e s c r i b e d f o r t h e h y b r i d c o n c c p t .

T h i s concepr eecms t o b e t h e most p r o m i s i n g of t h e t h r e e p r e s e n t e d , b u t i t i s d o u b t f u l t h a t i t c o u l d be i ~ r c o r p o r a t e d i n t o e x i s t i n g hub and r e t e n t i o n syetcnrs. However, s i n c e t h e s e a r e a s would p r o b a b l y need t o b e r e d e s i g n e d f o r advanced t e c h n o l o g y p r o p c l l c r s , t h i s corteept might b e a p p l i e d w i t h o u t undue d i f f i c u l t y .

S t r u c t u r a l C o n s l d e r a t i o n e I n a v a l u n t l l t j ctic s t r u c t u r a l i n t e g r 1 t y of advanced t e c h n o l o g y p r o p c l l c i r s c o n e i d c r n l ) l ~ ~ n t t o n t i o n nalst be g i v e n t o tha s t e a d y and a l t e r r ~ e C i n g l o a d i n g s e x p e r ir?r~csd i n 8;. ;feel. TIIQ s t e a d y l o n d e c o n e i e t p r i m a r i l y of c e n t r l f u g n l and t h r u s t I ~ V : ~ 6 , Tho a l t e r n a t i n g v i b r a t o r y 1 o a d s a r c d u e Ea b l a d e earodynaniic c * , ~ . ' l I ; i o n s , t o r s i o n a l e x c i t ; a t ion# Fronr tlie r e c l p r a c a t i n g e n g l n e , and rcRlL i rnccs w i t h tiarmonice o f r o t a r s p e e d . Aerodyna~nic lnE low c ~ n g l e a m u 1 nSy c x c t t o 1xP ~ L t e r n a t ing l o u d 8 which g e n c r u l l y doinincite on conve11t.tonu1 t u r b o p r o p i n s t a l l a t i o n e , wheronu e n g i n e a l t c r n u t lng t o r s i o n a l lorrrls d o n ~ i n a t e on c o i ~ v e n t i o t ~ a l r c c i p r o c c ~ t i n f i ! 3 1 1 s t i r l l a t L o n ~ . Zn nJ1 i n s t n l l n t i o ~ ~ s one s h o u l d clssure tlrut 1x1' raeonrot:r,e d o e s not: o c c u r i n ttir* nor~nibl oparibtlng HPM r a n g e .

TIIC s t e a d y load^ o n convcrrtionrrl propellers r a n u s u a l l y b a obcclined using l)csnn\ untrlys i s o r l unlpcd pcrronlcter m a t r i x nutnipuJ.at:lon t s c h n i q u e a .

V i b r a t o r y a n a l y s i s Is p r o v i d e d by c u r r e n t l y a v n i l a b J e a n a l y t i c a l t c c l ~ n i q u e s tttcit: a r c npp1irtrI)le t o GcncrnL A v i a t i o n p r o p o l l e r e , Tllese t c c l l n i q u c s dchrcr~ninc tiiorlc? frcaqucl'rclus w i t h f s f r accurclcy and v i b r a t o r y l o a d s ~11ic1 r c ? s u l t a n t @ t r t . s s c a w l t l ~ l n 23-30 p o r c c n t on t u r b i n e i n s t n l l a - t i o n a , l'tlr. d u t e r n r i n a t i o n of s t c o d y and v i b r a t o r y ef f e c t s on advancad t u c l i n o l o ~ ~ y p r o p c l l e r u , l n c o r p o r n t i n g conipositc n l u t e r i a l s and h a v i n g low aspect: r a t i o , swccp arid p r o p l e t s , nlrry rccjrrire t h e u s e o f mora s o p h i u t d c a t c d anczlyrica l t e c h ~ i i q u c l s Xikc f t n l t c elenicnt methods ( r e f .

13). 'I'hc e f f o r t o f a1 t c r n a t ink: o x ~ i t t r t l o n s from r c c i p r o c c l t i n g e n g i n e 6 is c u r r e n t l y riot i n c l u d r d i n cx l s t tnl; c r n n l y t l c n l nlodels. Experimental.

t e s t i n g o f s t r i s i n gugcd prolwl,lr!rti i s rc?llctl upon h e a v i l y f o r b o t h t u r b o p r o p und TIPC ipri)c.irt l n ~ 1 n s t a 1 1.ntions. 311 add4 t i o n t o a h s w i n g p r o p e l l e r b1iidc: ~ t r ~ ~ c c u r n l Intc}:ri t y tlrroug!i n t t c n t i o i r t o s t e a d y and v i b r a t o r y los\ri I l m t t s , lnc: f i r t ng suqtioncc, and 1xP e x c i t a t i o n s , s s u c c e e a f u J t l c s i ~ n nlilvt crvolcl s t i l l 1 rrnd c l a x s i c a 2 f l u t t e r .

S t a l l F l u t t c r . - Stall. f l t t t t c t r Ir; i t l.Flait i . y ~ l o u e c i l l a t i o n t h a t o c c u r s a t t h e h l u d T s f l r s t n a t u r r r l tors lona L I,'rc?qucncy when t h e i n t e g r a t e d spnnwisc? dnn~piug ht~c1orrics nc)ro o r n o g ; l t l v c * T h i s o c c u r s wl~en t h e b l n d e i s operating a l l : condi C l a n s o f v t ~ l o i ~ t t y a n d nnl:lc of ntttrck wtrere s l g u i f i e a r r t : b l a d e rrtul.1 is c n c ~ o u n t o r c d . I2or propc:lfctrs, Ehc most: c r i t i c a l cond 1 t l o n s arc? t h a sttitir* t h r u s t . t:lkc?-of f c o n d i t i o n and t h e r e v e r s @ t h r u s t landinp, c o t l d i t Con. S t n l l . f 1 i r t t e r i m s ~ c t u t ~ d wit11 t h e r e v e r s e p i t c h h r a k l n l ; p r o c v s s r.tla g c t ~ c , r i r l l y hc handled tiy p r o p e r l y o d j u s t i n g prope1li:r s r o p s t o uvoitl stir l l . Tlr i s l e a v c a t h e s t a t i c t~o11d i t i i 7 i 1 From (1 d e s i g n s t t r : ~ d p o i n t .

t a k e - o f f conciit i o n a s tlrc! r . r i t i c ; r l The emst I n ~ p o r t i ~ n t p c r i n t t o mi~icc r c h t ivc? L o tlw criteria is t h a t tila 8ctll.l. flirttcbr c l m r n r t t \ r istit> i s n f u n r t inn of blrrde) t a o r s i o n a l nnturcil Erequc~rcy , not t o r s l o n l i l s t if ft1cs8. S t a l l f l u t t e r w i l l o c c u r o n l y w i t h i n c c r t n d n 1:;inl:cs of rcclcrrt~d v o l o c i t l t ~ s wllerc Iliah angles o f a t r a c k o c c u r n\ul t h i s rrrnEc c l i n ~ i n l r ~ l t c s irs Iiwnn angle of a t t a c k is f l u t tur E r c c , t h e d e s i g n e r d e c r e a s e d . Tllu..; t o t ~ e comp l ~ l t c 1 y .ur t a l l h a s a c l ~ o i c o o f l i a r i t l u p , tllcl rlicrlli k1l:ld~ i ~ n t ; l t l n t a t t i i r k o r i n c r e a s i n g tile b l a d e n a t u r i r l frciq\tc\r\t-y t o s \ r r l ~ il vnluc. thcik t h c of s t a l l

f l u t t e r is c o m p l o t o l y a v e r t e d a t a l l b l a d e a n g l e s , These f o r e g o i n g o x t r o m e s i n d e s i g n c r i t o r i a a r e g o n e r l r l l y t o o r e ~ t r i c t i v e . An optimum d e s i g n u s u a l l y d o t e r m i n a s t h o b e s t compromise between maximum b l a d a a n g l e e x p e c t e d and t h e t o r s i o n a l f r e q u e n c y c r i t e r i a , 1.0. f o r e a c h a e r o d y n a m i c a l l y s i z e d p r o p o l j a r t h e r e is a maximun~ power l o a d i n g a s e o c i a t e d w i t h n minimum t o r s i o n a l f r e q u e n c y .

Although i n h e r a n t a t r i r c t u r r r l dampiny s u c h a s a v a i l a b l e i n c e r t a i n advanced c o m p o s i t e s c a n s i g n i f i c a n t l y improva s t a l l f l u t t e r c h a r a c t e r - istics, no p r o v e n a n a l y t i c a l mcthods n r e c u r r e n t l y a v a i l a b l e t o p r e d i c t t h e occu4i:tonce of s t a l l f l u t t c r and t o a v o i d s t a l l f l u t t e r i n a t e b i l i t i a s .

However, work i s c u r r e n t 1 , y underway t o e x t e n d h e l i c o p t e r a e r o e l a s t i c p r e d i c t i o n techniques t o G e n e r a l A v i a t i o n .

E m p i r i c a l rcduced f r e q u e n c y pornmetors n r e a v a i l a b l e f o r u s e by t h e C.A. m a n u f a c t u r e r s on c o n v e n t i o n a l p r o p e l l e r s . Unleas a n a l y t i c a l methocis a r e d c v a l o p e d f o r rrdvanced p r o p e l l e r s , t h o e m p i r i c a l methods w i l l have t o be c~ttcndccl by c x p c r i ~ n c n t e l t e s t i n g .

C l n ~ e i c a l F l u t t e r . - C l n s s i c a l f l u t t e r i s nn o s c i l l n t o r y i n s t a b k l i t y t h a t can o c c u r n t hifill o l r c r a f t : v e l o c i t i e s by on improper p h a s i c g o f blrrdc a l a s t i c r e s p o n s e and iaerodyndmic l o n d i ~ i g . l'wo o r more modes o f v i b r a t i o n may c o u p l e t o produce a d e t r i m e n t a l p h a s i n g o f t h e T h e s e modas a r c u f u n c t i o n of t h e d e s i g n o f p r o p e l l c r b l a d e l o a d j n g .

t h e p r o p e L l c r b l n d e s and a r c r e l o t c d t o t h e l o c a t i o n s o f t h e e l a s t i c a x i s , c e n t e r of p r u s s u r c nnd c c n c e r o f mnu8, and t h c b l a d e moments of i n c r t i u , The o c c u r r e n c e of c l o s ~ i c o l f l u t t c r is r e l a t e d t o t h e s p a c i n g t h c modes o v e r t h e propeller o p e r a t i n g range.

o f t h e E r e q u s n c i e s of E x i s t i n g t e c h n i q u e s f o r p r c d j . c t i n g niodo f r e q u e n c i e s are a d e q u a t e f o r c u r r e n t t e c h n o l o g y p r o p e l l e r s . l'hCsc tL?chniqucs c o n s i s t of gener- a t i n g a Campbcll p l o t by nlcens o f a s i m p l e beam t h e o r y h a v i n g a c e n t r i f u g a l sti i f e n i n 8 tcrnc, n t ~ d correlating these, t l l e o r c t i c a l r e s u l t s w i t h cxpr , r i m e n t o 1 mode f rr?qucncy dn t u . Tlie Canipbell p l o t p r o v i d e s a q u a l i t a t i v e a n a l y s i s t h a t determines i t : t h e modcs are w e l l s p a c e d a t o p e r a t i n g rpm'e. The p l o t c o n stlow i f t h e t h i r d or t o r s i o n mode is h i g h and u n l i k c l y t o c o u p l c w i t h ttic! f i r s t two b e n d i n g modes. T h i s The u s e of c o u p l i n g is t h e e x p e c t a d s i t u a t i o n f o r c l u s s i c a l f l u t t e r .

t h e s i m p l e beam t h e o r y w i l l n o t bc etfcquate f o r advanced t e c h n o l o g y t h e i r u n i q u c s h a p e s ( i . e . sweep and p r o p l e t s ) , p r o p e l l e r s b e c a u s e o f t h e i r composite c o n s t r u c t i o n , and t h e f a c t t h a t tire t h e o r y d o e s n o t a c c o u n t f o r t h e h l a d c aerodyneniic r e s p o n s e . Zmproved a n a l y t i c a l t e c h n i q u e s , l i k e f i n i t e elenicnt methods ttiot: e v a l u a t e b l a d e a e r o - dynamics, w i l l bo needed t o a c c u r c ~ t c l y p r e d i c t t h e mode f r e q u e n c i e s o f chc advanced techrlology p r o p c l l l c r s . A l s o , t h e work c u r r e n t l y underway t o e x t e n d h e l i c o p t e r a c r o e l a s t i c p r e d i c t i o n t e c h n i q u e s t o G e n e r a l A v i a t i o n p r o p e l l e r s c a n be a p p l i e d t o c l a s s i c ~ l a s well as s t a l l f l u t t e r .

A v o i d i n g Reson*nces.- Avofding r e s o n a n c o e o f j n t a g e r h a r m o n i c s (mode c o u p l i n g ) c o u l d b e n v e r y f e a s i b l e d e s i g n t n s k when t h e b l n d e e are t o b e f a b r i c a t e t i witir cotrrpoeltue. ilowrjver, tlrtt e f f e c t s o f f r e q u e n c y c h a n g e e w i t h b l a d e p i t c h must b e c o n s i d e r e d t o g o t h e r w i t h t h e v a r i a t i o n s i n rpm's .

s e l e c t e d Lor d e s i g n . S h o u l d t h i s r e p r e s e n t a re t h e r w i d e v r r i a t i o n , it may b e n e c e s s a r y t o s u s t n i n a t r c r n s l e n t t h r o u g h a n i n t e g e r h a r m o n i c a s t h e rpm is v a r i e d f r o m t a k e - o f f t o n c r u i s e c o n d i t i o n . I n a d d i t i o n , (I t h e s y s t e m s mount i n g uclrur a l f r e q u e n c y must b e c o n s i d e r e d t o a v o i d w h i r l f l u t t e r t y p e o f p r o p e l l e r i n d u c i n g l o a d s .

The m a j o r p o i n t IB, h o v e v e r , t h n r w l t h t h e a b i l i t y t o t a i l o r s t i f f n e s s a n d mass d i s t r i b u t i o n s t h r o u a h t h o u s e o f c o m p o e i t e e , t h e t a s k o f c o n t r o l l i n g t h e n a t u r a l f r e q u e n c y and mode s h a p e s s h o u l d be e a s y r e l a t i v e t o t h e same trwk l i s i n g t r a d i t l o n a 1 m e t a l m a t e r i a l s . A s e c o n d major p o i n t i s t h a t n o p t l r t i c u l a r Elatwise o r c h o r d w i s e f r e q u e n c y is b e t t e r t h a n any o t h e r u s l o n g n s r e s a n a n c c t s a v o i d e d a n d t h e c r m p l i f i c a t i o n o f n o r m a l p r o p e l l e r Loads is w i t h i n s t r u c t u r a l i ~ ~ t e g r i t y l i m i t s .

F a t i g u e . - Beccrustr of Lhc h i ~ h f r e q u e n c y o f p r o p e l l e r loading^ i n t h e n o r m a l a i r c r a f t e n v l r o n m c n t . t h ~ p r o p e l l o r must be d e s i g n e d f o r a f a t i g u e e n d u r a n c e l i m i t well a b o v e t h e s e load^. G e n e r a l l y f o r t u r b o p r o p a i r c r a f t , t h e Aq d e s i g n p e r n r n e t c r is s e l e c t e d s u c h t h a t t h a h i g h l y p r o b a b l e g u s t environment: and normal r,.aneuverinfq environnrent: a r e c o n t a i n e d w i t h i n t h i s Aq e n v e l o p e (A is a n g l e o f a t t a c k and q is dynamic p r e s s u r e , a n d t h i s p o r a m c t e r is t h e bnensure of t h e I p e r r e v h l a d a l o a d i n g s ) .

F o r p i s t o n powered a i r c r a f t , t h e Aq l o a d s a r e g e n e r a l l y overshadowed by t h e t o r s i o n n l l o a d s i n d u c e d hy t h u e n g i n e t h r o u g h t h e p r o p e l l e r s h a f t a n d / o r t h e moLlons iuductvi i l l t htl p r o p e l l e r p l a n e by t h e n a t u r a l f r e q u e n c y o f t h e m o u n t i n g s y e t c w .

With a t j i r c c t ntntar1:ll s u b s t i t u t i o n o f c o ~ n p o s i t c s f o r aluminum, t h e f a t i g u e s t r e n g t h irnproves hy c ~ t lcast a f a c t o r of 2 . F o r e x a m p l e , a material substitution o f E-Glass f a r aluminum i n a p r o p e l l e r t h a t h a s a s a t i s f a c t o r y f a t i g u e l q f e w i l l rest11 t i n e x c e s s f a t i g u e s t r e n g t h a s s u m i n g t h e b l a d e f r e q u e n c i e s still a v o i d r e s o n a n c e s .

S i n c c t h e r e s u l t i n g d e s i g n is n o t c r i t i c a l from a s t r e n g t h s t a n d p o i n t ( w i t h i n t h e f r e q u e n c y c o n s t r a i n t s ) , t h c p o t e n t i a l f o r r e d u c i n g t h e c r o s s - s e c t i o n o r t h i c k n e s s o f the a i r f o i l and h e x e t h e w e i g h t is v e r y l a r g e .

E x p e r i e n c e and F a t i g u e t e s t d a t a 011 m a t e r i a l p r o p e r t i e s w i l l d i c t a t e a l l o w a b l e a 1 t e r n a t S n g s t r e s s l e v e l s and d e t e r m i n e t h e a p p r o p r i a t e f n t i g u e l i m i t s w i t h c o n ~ p o s i t e s a s is the cnsc w l t h aluminum a l l o y s .

S t r u c t u r a l A d v a n t a g e s of C a m p o s i t e s . - l'hc a d v a n r a g e o f c o m p o s i t e m a t e r i o 1 , s i n p r o p e l l e t b l a d e s i a t h a t t h e e n g i n e e r c a n r e a d i l y t a i l o r s e c t i o n s t o o b t a i n more f n v o r n b l u s t l f f n r s s d i s t r i t r u t i o n s t h a t w i l l c o n t r o l t h e f r e q u e n c y c h a r n r t a r i s t : t c s a n d , t o n l e s s e r d e g r c e , t h e p r i m a r y mode s h a p e .

O r i e n t a t i o n o f f i b e r s s ~ ~ c - h a s u n i d . i r i ~ c t i o n a 1 o r c r o s s p l y a n d l o r mixed nrodulus m a t e r i a l s a r c t h c tcchniclucs t h a t a r e u s e d t o o p t i m l z e s t r e n g t h

and f raquancy c h n r n c t o r i s t i c e a t minimum w a i g k t .

Using t h e l o a d s , frequency, crnd f l r ~ t t o r c r i t a r i a , Ire pruvioucrly d l e c u s e o d , nn advirrrcad dasigrr would bo i t ~ r r r t a d t o o b t a i n n e o l u t i o n t h a t e u t i s f i e s tlru s t r a t i ~ t h and frequency c r i t o r i n and t h a t u t i l i m e e t h e moat c o ~ t e f f e c t i v e conrbinatj,on o f m o t o r l n l e .

T h i s i a a com~rlex n r c u t o a d d r c s o s i n c e t h e r o l n t i v a i m p o r t a n c e of ecbch advenccd t e c h n o l o g y a r e n is cfupcndcnt upon s e v e r a l f a c t o r s , mimy of wlilch a r c s u b j u c t i v a i n n u r u r e and p a r t i c u l n r t o t h e n e e d s and d c s i r c s o f i n d i v i d u t r l c o r p o r l r t c p o l i c y . Il'lre trndc-of f a r r n l y s i s of t h e mnjor p r c p c l l c r ctesign p a r n m c t c r s pcrformad by McCnuley and t h o "optimum p r o p e l l e r " d e s i g n s e l c c t c d f o r eirch n i r c r a f t a r e bneed upon tlreec f n c t o r s . T h e r e f o r e , t h c "optimum propeller" f o r e a c h ~ r i r c r t t f t c o n s i s t s o f t h c c o m h i n n t i u n of prcopcller s i z c , d e s i g n purnmctern and ndvanccd tcclrtrolouies w ! r lctr i n t h e o p i n i o n o f HcCauley r e p r e s e n t rlrc most s u l t i r h l c * p r ~ p c l l ~ r f o r t~itcli Genertrl A v i a t i o n t l p p l i c a e i o n S 7 r o p e l l c r Opt lmiztrt'ion The c h n r n r t e r i s t i e 8 uf t h e s o - c n l I'tl " o p t imunrtt udvulrced tochnolony p r o p c l l c r s d c s i ~ n c d l o r ctrch c r i r c r n f t arc! shown i n T u b l e 5. The o p t i m i a e ( i p r o p c l l c r s shi7\~n meet VAK P a r t 36 81nd Pnrc 36 - SdB(Aj a s indicutc?d. The gaonretric crdvnnccd toclrnolofiy p r o p e l l e r d e s i g n s a r e t h o

sunre f o r m e e t i n & FAR P n r t 30 and I'AR I'nrt: 36 - SdU(A) . 'I'hc advanced

t c c l i n o l ~ g y p r o p c l l e r s were o r i g l n n l l y cicsijincd t o nrcct, FAR P a r t 36- SdB(A). The 5dH(A) incrcnsc! t o FAR P o r t 36 was uccomplished by i n c r e n s e s i n e n 8 i n c rpm r n t i t r u . A t i t t i p s p c ~ d nbovcl 700 f p s , s t u d i e s hove shown t h a t a p p r o x i n m t e l y n 100 i p s chnngc) i n tlrc t i p speed w i l l . a f f e c t t h e o v e r r r l l eoirnd prcssurcl l e v e l \)y i r h o t ~ t SdU(A) . A bat-lic u s s u m p t i a n made tiera i s t h a t cnp,j.ucs o f t h c n c n r E u t u r c can bc rntctf a t l o w e r rpm's s o t h a t power l a u d t n g r e d u c t i o n s cnrr bo c o t r t r o l l e d by r e d u c i n g rpm w h i l a i n c rerrsitrg dinmc t e t .

The p r o p c l l c r s wcrc o p t i m i z e d f i r s t f a r pcrformunce, checked f a r n o i s e l e v n l and i t e r a t e d back t h r a u n h performance u n t i l t h e r e q u i r o d n o i e a l c v e l was s n t i s F i c d and t h e h e s t performance p o s s i b l e was o b t n i n c d .

The r e q u i r e d b l a d e ~ e o m c t r y t o s t i t i s f y pcrformnncc nnd u c o u s t i c s woe t h e n checked f o r s t r u c t u r a l s o u n d n e s s us in^ i r p p r o p r i n t c c o m p o s i t e m u t c r i t l l s .

Xn detcrmininp; t h e impact o f weiglit reductions t h r o u g h t h e uso o f cornpasites It must b c cmphnsizcd t h a t t h c b l a d c wc;ip;ht s a v i n g s f o r c o n t r o l l u b l c p r o p c l L c r s were n I - c s u l t of tl d i r c c t raplncemont o f alum- i r r i ~ m b l a d e s o n l y . T h i s d o c s not: t n k c j n t o a c c o u n t any p o t e n t i e l w e i g h t

r u d u c t l u n s 111 the I ~ u b clrtba. For f i x s d p i t c 3 h p r o p e l l e r e e t o t a l r e p l i l c a - nrent was a t i t i u ~ n ~ d . A l s u , i ~ r o r i l c r t o a c l r i e v e tlre d e s i r e d compromise of a d v a n c e d c e c h n o l o g i t * s betwisetr p ~ r f o r m s n c c and n o i s e , t h e p o t e n t i a l w e i g h t s u v i n g s w e r e n o t t r e c v t ~ s s a r i l y r?ptimuni. En o t h e r w o r d s , t h e t r c n d ~ o f J e c r c n s t j d power 1 oad In& t h r o u g h d i n m e t a r increases, i n c r e a s e d r~umber o f h l a t l c s , tiwccap i ~ r r t l p r t ) p l t ' l ~ t e n d e d t o i n c r e a s e weight: w h i l e b r l n ~ o f f e e t p o r t l'il l y t l r r c ~ u f i t ~ lower hliicte e c r i v i t y fi1c.tar.s and l o w e r t h i c k ~ r ~ s ~ r a t l o s . t'rt)pcl l e r i ' o ~ t (1979 tlol l u r t i ) rind w e i g h t a r e d e t e r - ~ n l n c d f r o n ~ tire c a ~ p i r i c ~ . r 1 r ~ l i t t luntrlrlps p r c s i ~ n l c d i n Appcwdices h and 8. Appenlliccbs A i ~ l ~ d 14 w e r e ~1k:rlvcd fro111 d a t a pre:;ented I n r e f e r - e n c e 14 and m o d i f i e d uti r u q u i r e d . 'The i t h i i r d c . t u r l s t l c s of t h e o p ~ i - 1111 zed a d v o n c c d tecllni)ltrp,y p r u p e 11 c r ~ ( l ' i ~ b l e 5) J i f f ~ r c o n s l d e t e b l y fro111 t h u s c of c b u r r e n t tcclrnology p r o p e l l e r s ( T s b l c 2 ) i n t h a t tlley i n c o r p o r a t e sweep, p r o p l e t s , udvunclcd i l i r f o i l s , h e v e t h i n n e r and l o n g e r I ) l a d c s , and g e n e r a 1 l y Iravc ;I l L ~ r g t * r number o f l o w e r e c t i v i t y f a c t o r blodlss. 'I'hc l l t o 2 0 I)erc-c*nt w e i g h t r e d u c t i o n shown by t h e s e t a b l c > s Fcrr t h c I i r l ~ ; r ~ r c ~ e r l Lcl'lit10 lt11:y p r u p o l l c r s o v e r t h e c u r r e ~ l t tech- ~loLagy prtrpe 1 l c r s is due t o ttrc 1 1 s ~ of r w m p o s i t c t i r a t e r i a l s . B e c a u s e of t h e i r ltiwctr wciglrt ,111d I ~ i g l i r I* t ~ f ' f icic%ncy t h e udvancc.d te,!~nology p rupcl LLers r e q u i r c d l ces eilp,i~ie powiht- t lr:ru the c u r r e n t teclrnolofiy p r o p e l 1t.11-H. 1 t i s i l l st) dpp:i rtlrrt from ,I c*onrparisun of T a b l e s '? and 5 t h a t t h c ~ CL)Y t o f tlrc' ; I L ~ V ~ I I I ( ' L ~ ~ t c~i'hnolo1:y propellers was h i g h e r .

'l'lrc s i g ~ r i f l c . : i n ~ ~ c \ 0 1 t h t ~ s e hlgt~cbr ~~11st.s w l l l h e o x p l a i n c d l a t e r when adil r c s s i n g Miss Lon S t u3 i t ~ s .

The. p o t c u t l a 1 is r u i s e p t $ r l orlnrrlrcac gcr iris oh t o i l r e d by t h e "optimum" p r o p e l l o r dcsigncxl l o r etich of t.111~ s t u d y a i r c r a f t a r e p r e s e n t e d i n F i g u r e 30. Thc udvan~3cd tcchnci logy c l a n e n t c ; rlf f e c t i r l g p e r f o r m a n c e h e v e b e e n brokew down i n t o t . h r V i ~ ~ i l t e g ~ r l c s . T h o s ~ c > o n ~ i d e r e d a s i n d u c e d o l fccl tr; i.ncll udc pclwrr 1 o a d i n g , number u f b l a d e s , t i p s p e e d , a n d p r o p l e t s . B l a d e drap, e f t e v t s include a c t i v i t y f a c t o r , t h i c k n e s s r a t i o , s w e e p , a i r f o i l s : I I I ~ S U ~ ' ~ : ~ I V I ' f i n i s h . l n t c r f e r e n c c e f f e c t s a r c a t t r i b u t e d t o n d c c 1 lcs bluckagcl und s p i n n e r / b l t i d c shenik l o s s e s .

T h e g a i n s i n c r u i s c perf~iraitincw Crom i p l ~ u r c 30 rarrge f r o m a b o u t 5 t o 9 p e r c e n t . ' t h e Iligl\cr e f f l c i e n c y g a i n s o c c u r r e d for t h e h i a h e r s p e e d a i r c r a f t , L.c. 414A, 441 and 19 PAX c o n ~ n ~ u t r r . The h i g h e r g a i n s arc a t t r i b u t e d t o 8 r e : l t c r r e d u c . t l o n s i n i n t c r f e r c n c e l o s s e s f o r t h e s e a i r c r a f t . T h e g o i n s frcl111 1 1 1 t e r t e r ~ n c e r e d u c t i o ~ ~ w e r e 1.3 t o 2.3 p e r c e n t f o r t h e l o w e r s p e e d i i i r c - r ~ l f t (172N, A.I881), 210M) a n d 4 . 2 t o 5.0 p e r c e n t f o r t h e h i g h c r s p e e d a i r c r a f t , E f f i c i e n c y g a i n s i r o n r e d u c t i o n s i n i n d u c e d l o s s e s a n d b!;idc d r a g l o s s e s w c r c f a i r l y con- s t a n t f o r a l l a i r c r a f t .

1.11 order t o scte why c f f L C it*nr>y g a i n s t i t t r i b u t e b l e t o the r e d u c t i o n i n clntcrf e r c n c : ~ l o s s e s bec;rnie hip,Iic+r f u r t h e h i g h c r s p e e d a i r c r a f t , F i g u r e 31 was construt.tc.d t o show t h e i n d i v i d u a l c o n t r i b u t i o n of e a c h i n t e r f e r e n c e c l e m e n t . F r a n ~ lcigurc 31 i t : i s e v i d e n t that t h e e f f i c i e n c y g a i n s d u c t o lorprtr\tcd n a c e l l e h l i w k a k c c f i c c t s d r o p s d r i ~ n ~ a t i c a l l y f o r two o f t h e Irighcc s p o c d a i r c r a f t ( 4 4 1 , 19 1'h)i). T h i s is b e c a u s e o f

t h e low n a c e l l e body t o p r o p e l l e r d i a m e t e r r a t i o of t h e t u r b o p r o p i n s t a l l a t i o n e , It i e a l s o c l e a r from t h i e f i g u r e t h a t t h e h i g h e r e f f i c i e n c y g a i n e f o r t h e h i g h e r s p e e d a i r c r a f t (414A, 441, 19PAX commuter) a r e a t e e u l t of a l a r g e r r e d u c t i o n i n e p i n n e r / b l a d e shank d r a g . Theee r e s u l t s a r e c o n e i s t e n t w i t h t h e f a c t t h a t t h e s p i n n e r / b l a d e ellank d r a g is a f u n c t i o n o f dynamic p r e s s u r e . Thum t h e amount of d r a g s u b j e c t t o r e d u c t i o n is l a r g e r f o r t h e h i g h e r s p e e d a i r c r a f t , A i r c r a f t M i s s i o n S t u d i e e The p r o p e l l e r t r a d e - o f f s and r e s u l t a n t "optimum" p r o p e l l e r d e r i g n e a r e t h e d r i v i n g f o r c e a f f e c t i n g i m p o r t a n t a i r c r a f t / m i e e i o n charac- t e r i s t i c s . The performance g a i n s shown i n F i g u r e 30 and t h e w e i g h t r e d u c t i o n s p o s s i b l e t h r o u g h t h e u s e o f compoeitee t h a t were shown i n T a b l e 5 w i l l have a b e n e f i c i a l e f f e c t on a i r c r a f t / m i e e i o n c h r r a c - t e r i s t i c s . To d e t e r m i n e t h e e e e f f e c t s , a mieeion e t u d y wae performed f o r e a c h a i r c r a f t e x c e p t t h e A 1 8 8 B . The c h a r a c t e r i e t i c e o f t h e air- c r a f t w i t h b a s e l i n e p r o p e l l e r s o r e l i s t e d i n T a b l e 6. The m i e e i o n s t u d y r e s u l t s f o r t h e A1888 a i r c r a f t were determined by assumed t r i r n i - l a r i t i e s t o t h e 210M a i r c r a f t , I n p e r f o r m i n g t h e m i e s i o n e t u d y , e a c h a i r c r a f t was r e s i z e d t o t a k e f u l l a d v a n t a g e of t h e advanced technology b e n e f i t s a s s i g n e d t o e a c h "optimum" p r o p e l l e r , Payload, r a n g e , s p e e d and a i r c r a f t l i f t t o d r a g r a t i o were k e p t c o n s t a n t and a two h o u r c r u i s e m i s s i o n was assumed.

I n t e r m e d i a t e r e s u l t s of t h e m i s e i o n s t u d y a r e p r e s e n t e d i n F i g u r e 32. These d a t a a r e t h e r e s u l t s from a m i s s i o n a n a l y s i s computer pro- gram and show, f o r e a c h a i r c r a f t , t h e e f f e c t s of changes i n p r o p e l l e r e f f i c i e n c y and w e i g h t on t h e e n g i n e horsepower r e q u i r e m e n t s and a i r - c r a f t g r o s s w e i g h t . The a i r c r a f t g r o s s weight r e d u c t i o n e r e s u l t i n g from t h e b e n e f i t s of t h e o p t i m i z e d advanced technology p r o p e l l e r a were o b t a i n e d from t h e s e d a t a u s i n g t h e e f f i c i e n c y improvements ( F i g u r e 30) and w e i g h t r e d u c t i o n s ( ~ a b l e s 5 and 2) a c h i e v e d by e a c h advanced The r e q u i r e d power o f t e c h n o l o g y propel1,er d e s i g n . t h e advanced technology p r o p e l l e r f o r each a i r c r a f t :*as determined i n a s i m i l a r manner. The f u e l burned was t h e n determined from t h e power and t h e s p e c i f i c f u e l consumption ( T a b l e 6) a s : hp x X power x SFC x 2 and compared t o t h e f u e l burned f o r t h e b a s e l i n e c a s e .

The o p e r a t i n g c o s t of e a c h a i c c r a f t was based on a f u e l c o s t of $ 2 p e r g a l l o n . The o p e r a t i n g c o s t d a t a f o r e a c h a i r c r a f t were d e r i v e d from a c o s t a s s e s s m e n t o f e n g i n e and a i r f r a m e p e r i o d i c main- t e n a n c e , f u e l and o i l burned, r e s e r v e s f o r e n g i n e and ai,rframe p e r i o d i c o v e r h a u l , r e s e r v e s f o r a v i o n i c s , systems and m i s c e l l a n e o u e items.

The r e s u l t i n g r e l a t i o n s h i p between t h e f u e l c o s t and t h e o p e r a t i n g c o s t per h o u r f o r e a c h b a s e l i n e p r o p e l l e r - a i r c r a f t combination a r e

a s f o l l o w e :

A l r c r a f t 1 7 2N - 1 9 PAX 210M 4 14A 4 4 1

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Fuci 1 $18.17 $32.88 $ 74.00 $142.00 $272.34 ope rut in^ C o s t $28.13 $53.31 $125.28 $245.25 $427.00 The o p e r a tinp, c o a t s o f he a d v a n c e d t e c h n o l o g y p r o p e l l e r powered a i r c r n f t w e r e deterrrrined f r o m t h e a b o v e d a t a by a s s u m i n g t h a t t h e f u e l c o s t p o r t i o n o f t h e o p e r a t i n g c o s t was r e d u c e d by t h e same r a t i o fie t h e f u e l s o v i n g s b u t t h a t t h e r e m a i n i n g p o r t i o n of t h e o p e r a t i n g c o s t was c o n s t a n t .

T h e a i r c r a f t r e t a i l c o s t r e d u c t i u t \ r e s u l t i n g from t h e a p p l i c a t i o n o f a d v u n c e d t e c h n o l o a y p r o p e l l e r s was d e t e r m i n e d from t h e w e i g h t s a v i n g s o f t h e r e s i z e d n i r c r a f t conlbiriad w i t h t h e p r i c e p e r pound d e t e r m i n e d from T a b l e 6 , and i n c l u d e d t h e i n c r e a s e d c o s t o f t h e a d v a n c e d t e c h n o l o g y p r o p e l l e r .

The r e s u l t s of: t h e m i s s i o n s t u d l e e s h o w i n g t h e b e n e f i t s o f t h e a d v a n c e d t e c h n o l o g i e s t h a t were a p p l i e d t o o b t a i n a n "optimum" p r o - p e l l e r f o r e a c h a i r c r a f t a r c p r e s e n t e d i n F i g u r e s 33 t h r o u g h 36.

T h e s e f i g u r e s show t h e p e r c e n t a g e ~ n t n a a f t h e advanced technology p r o p e l L e r powered n i r r r a f t o v e r t h e b u s e l i n e p r o p e l l e r powered a i r - c r a f t . Tl,e g a i n s a r e sllown f o r the advaticed t e c h n o l o g y p r o p e J L e r powered a i r c r a f t t h a t meet t h e FAR P u r r 36 n o i s e c o n s t r a i n t a n d t h e FAR P a r t 36 - SdB(A) n o i s e c o n s t r a i n t . b o t h c a s e s a r e comptlred t o b a s e l i n e p r o p e l l e r powered n i r c r a f t t h a t meet o n l y t h e BAR P a r t 36 n o i s e l e v e l . The d i f f e r e n r e i n t h e ~ d v n n c e d t e c h n o l o g y p r o p e l l e r g a i n s between t h e s e n o i s e l e v e l s r e p r e s e n t s a p o t e n t i a l p e n a l t y o s s o - c i n t e d w i t h t h e n1ore s t r i n g e n t n ~ ~ i s e t e k u l a t i o n .

The d a t a p r e s e n t e d i n F i g u r e 33 f o r t h e FAR P a r t 36 n o i s e con- s t r a i n t show t h a t t h e a p p l i c a t i o n o f a d v a n c e d t e c h n o l o ~ y t o G e n e r a l A v i a t i o n a i r c r a f t h a 8 t h e p o t e n t i a l o f r e d u c i n g a i r c r a f t t r i p f u e l c o n s u m p t l o n by 8 t o I 8 p e r c e n t . The r e s u l t s o f t h i s s t u d y a l s o i n d i - c a t e t h a t t h e f u e l s a v i n g s would v a r y w i t h t h e t y p e of a i r c r a f t , w i t h l o w e r c r u i s e s p c e d a i r c r a f t h a v I n ~ LI f u e l s a v i n g s o f t h e s m a l l e r , 8 t o 10 p e r c e n t nnd t h e l a r g e r , h i ~ h e r c r u i s e s p e e d a i r c r a f t h a v i n g a F u e l s a v i n g s o f 1 4 t o 18 p e r c t l n t . Tkt> c f f e r t s o f a more s e v e r e f u t u r e n o i s e c o n s t r a i n t on t h e a d v a n c e d t e c h n o l o g y p r o p e l l e r powered s i r c r a f t was iilso s t u d i e d ilnd L n d i c a teci t h i l t f u e l s a v i n g s would b e r e d u c e d by a b o u t o n e p e r c e n t s h a r r l d a 5dU(A) l o w e r n o i s e l e v e l b e r e q u i r e d .

With a d v a n c e d t e c h n o l o g y p r o p e l i e r s , a i r c r a f t o p e r a t i n g c o s t s were r e d u c e d a b o u t 5 t o 6 p e r c e n t ( F i g . 34, FAR Jh) and showed no s i g n i f i c a n t v a r i a t i o n w i t h t h e Cvpc of a i r c r a f t s t u d i e d . The a i r c r a f t

retail a c q u i e l t i o n c o s t s were reduced a b o u t 8 t o 1 6 p e r c e n t w i t h t h e a p p l i c a t i o n o f advaticed t e c h n o l o g y p r o p e l l e r s (Fig. 35, F A ! ? 36).

Although t h e c o s t e a v i n g e v a r i e d c o n s i d e r a b l y , t h e r e waa no l a r g e a i r c r a f t r e l a t e d t r e n d t o t h e d a t a , 0 0 t h t h e o p e r a t i n g and i r c q u i r i t i o n c o s t s a v i n g e would b e d i m i n i s h e d bv a b o u t 1 p e r c e n t o r l e a s i f t h e SdB(A) lower n o i s e l e v e l were imposed. The o p e r a t i n g c o o t g a i n r weve d u e p r i l n a r i l y t o t h e f u e l s a v i n g s and t h e r e t a i l c o a t g a i n s t o t h e r e d u c t i o n i n t h e s i z e and a s s o c i a t e d c o s t f o r t h e a i r f r a m e l e n g i n e o f t h e r e s i z e d a i r c r a f t . The h i g h e r advanced t e c h n o l o ~ y p r o p e l l e r c o r t e (comparing T a b l e s 2 a c d 5) d i d n o t 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 r e t a i l a i r c r a f t c o s t s a s r e t a i l p r o p e L l e r c o s t s r o p r e e e n t e d l e e s t h a n 4 1 / 2 p e r c e n t of t h e s e c o s t s f o r t h e a i r c r a f t c o n s i d e r e d i n t h i s stud,y.

A i r c r a f t w e i g h t when r e s i z e d t o b e n e f i t from t h e a p p l i c a t i o n o f advanced p r o p e l l e r t e c h n o l o g y , was reduced a b o u t 6-10 p e r c e n t f o r t h e FAR P a r t 36 n o i s e l e v e l c a s e (Fig. 36). T h i s improvement wa6 r e d u c e d by less t h a n 1 p e r c e n t when t h e 5dB(A) lowi?r n o i s e l i m i t was a p p l i e d t o t h e advanced t e c h n o l o g y p r o p e l l e r / a i r c r a E l .

Technology Program P 1 g It is a p p a r e n t f r o m t h i o s t u d y t h a t advancements i n p r o p e l l e r t e c h n o l o g y c a n p r o v i d e s i g n i f i c a n t performance and c o ~ t improvemente i n f u t u r e G e n e r a l A v i a t i o n a i r c r a f t . A t e c h n o l o g y prograrn w i t h a t t e n t i o n t o advanced a n a l y t i c a l p r e d i c t i o n methods, c o m p o s i t e m a t a r i - a l a and o t h e r p r o m i s i n g c o n c e p t s , Is needed t a d e v e l o p t h e t e c h n o l o g y and i n t e g r a t e i t i n t o a d e s i g n system s u i t a b l e f o r u s e by t h e G e n e r a l A v i a t i o n i ~ i d u s t r y , The g e n e r a l t e c h n o l o g y e l e m e n t s of t h i s program a r e shown i n F i g u r e 37. T h i s program would dc?velop tile t e c h n o l o g y f o r more e f f i c i e n t , q u i e t e r , s a f e r and l i g h t e r w e i g h t p r o p e l l e r s ; i n t e g r a t e t h e s e t e c h - g i o g i e s i n t o a d e s i g n s y s t e m s u i t a b l e f o r u s e by t h e G . A . i n d u s t r y ; and v e r i f y t h i s t e c h n o l o g y i n a model and f u l l s c a l e program.

The t e c h n o l o g y development a c t i v i t i e s would i n c l u d e a d e t a i l e d e v a l u a t i o n t o d e t e r m i n e t h e d e s i g n t e c h n o l o g i e s and new o r improved a n a l y s e s t h a t would b e r e q u i r e d t o u d e q u a t e l y d e s t g n f u t u r e advanced G . A . p r o p e l l e r s . T h i s e v a l u a t i o n would d e f i n e t h e improvenents needed i n e a c h t e c h n o l o g y a r e a ( ? . e , , aerodynamics, c o m p o s i t e s , a e r o - e l a s t i c s , and a c o u s t i c s ) t o a c h i e v e a w o r k a b l e , u n i f i e d d e s i g n methodology. A t t r a c t i v e advanced t e c h n o l o g y c o n c e p t s ( s u c h a s p r o p l e t e , swoep, a e r o - - a c o u s t i c a i r f o i l s , h y b r i d i z e d c o m p o s i t e s , and a d v ~ n c e d c o m p o s i t e b l a d e d e s i g n c o n c e p t s ) would b e i d e n t i f i e d i n t h e e v a l u a t i o n and a p r e l i m i n a r y a s s e s s m e n t o f t h e s e would d e t e r m i n e t h e p o t e n t i a l b e n e f i t of e a c h . C o n c e p t s showing t h e h i g h e s t p o t e n t i a l would b e s e l . e c t e d f 3 r f u r t h e r a n a l y t i c a l ~ n d e x p e r i m e n t a l e v a l u a t i o n .

Upon c o m p l e t i o n o f t h i s d e t a i l e d e v a l u a t i o n s t u d y , advanced t e c h n o l o g i e s would b e developed i n t h e a r e a s o f aerodynnmics, a c o u s t i c s ,

aernelastico, and composite structures, In tbe area of ~nrodynamlcs and more specifically advanced airfoil deeign, NASA has continually made efforts in improving coaanunicationr with the General Aviation community over the past rev~ral yearr through workehopa, symposiums, conferences, etc., and from tlreec have come airfoil deeign implementation schadulee satisfying the needr of win8 designers. What is needed now is an airfoil technology plan to derign airfoils specifically tailored Ear the widely varying fluid flow conditions which prevail along a propeller blade.

Advanced airfoils not only have the potential to improve propeller efficiency, but also (and perhaps more importantly) to lower the activity factors required for peak performance at a given deeign condi- tion and thereby reduce propellor weight.

Three dir,renaional f ] . o w field analytical techniques that account for the presence of the propeller and nacelle must he developed t o the point of commercial acceptability. There should be future testing including a wide variety of propeller/nacelle conf igurotions covering the broad range of nircraftlanginc combinations rypical of the General Aviation fleet.

Flow field analysis must be expanded to include the previously mentioned interference effects between the spinner and blade shank that were reported from the results of recent wind tunnel testing at NASA-Lewis Research Center. Additional effort is needed to better quantify and understand the mechanism behind this interference pheqom- enon. NASA should support analytical studies to predict spinner-shank icterference effects which could then be incorporated into strip analysis techniques for a more accurate determS,nation of installed propeller performance.

Aerodynsdc design technology should include analyses that properly account for advanced concepts such as sweep and proplets, for example, and assess propeller/nacelle/aircraft interactions in addition to propeller/spinner interference effects.

In order to adequately assess the structuraS feasibility of various composites for advanced propellers, new high technology analysis is required. In addition, design and manufacturing concepts must be developed, Manufacturing concepts Including tooling requirements and proces8 development must be studied in detail for specific applications, weighing the advantages of each. The result would be a preliminary tesign that incorporates the root attachment, amount of core, fiber- matrix system, leading edge and tip treatments, etc. The preliminary d,esign would then be analyzed by three dimensional finite element analvsis since several assumptions are inherent in the initial design.

Modeling allows economical iterations in the convergence process to a final design.

Tha t o t a l c o a t o f c o m p o s i t e b l a d e 8 must be n e a r l y c o m p e t l t i v e w i t h aluminum b l a d e s i n o r d e r t o r x p a r i e n c a w i d e u a e i n G e n e r a l A v i a t i o n . Rieeoarch i n t o low c o e t f a b r i c a t i o n t e c h n i q u e s a n d p r o p e r d ~ s i g n p r o c e d u r e s are t h t ~ key t o a c h i e v i n g c o s t c o m p a t i t i v u n a s e .

It a p p e a r s t h a t comlposlros w i l l f i r s t ; see w i d e s p r a a d c o m e r c l a l a p p l i c a t i o n s on l o r g e , complax, h i g h l y s o p h i s t i c a t e d m u l t i - e n g i n e t y p e a i r c r a f t w h e r e e a c h pound o f p r o p e l l e r w e i g h t s a v i n g s h a s a s i g n d f i e a n r i m p a c t .

On t h a o t h e r h a n d , It is I m p o r t a n t t h a t c o m p o s i t e s are s t u d i e d f o r h i g h volunre r e c i p r o c a t i n g c n g l n c n p p l i c a t i o n s where q u a n t i t y w i l l d i c t a t a f a a s i b i l j t y r a t h a r t h a n a l o r g e c f f o c t on a par a i r c r a f t b a s i s .

Reconunended tcchtio%ogy I n a e r o e l a s t l c b i would i n c l u d e d e v e l o p m e n t o f b e t t e r u n s t e ~ d y a c r o d y n n m i c s and s t r u c t u r a l dynamic a n a l y s e s t o b e t t e r model p r o p e l l e r f o r c e d ~ x c l t a t i o n s and e v a l u a t e f l u t t e r c h a r a c t e r i s t i c s .

S i n c e many t e c h n o l o g y e l e m e n t s t h a t imprcvvo p e r f o r m a n c e h a v e a n a d v e r s e e f f e c t on a c o u s t i c s , and f u t u r e government r e g u J . a t i o n s c o n t r o l l i n g n o i s c limits w i l l p r o b a b l y be more stringent:, i t is s t r o n g l y recommended that: r e s e a r c h fundinp, hc expended i n t h i s a r e a , The a c o u s t i c t e c h n u l o g y inip rovcmcnts ~ h o u l d i n c l u d e t h e d e v e l o p m e n t o f a n a l y t i c a l p r o g r a m s t o a c c u r a t e l y p r e d i c t t h e n o i s e o f p r o p e l l e r s i n c o r p o r a c i n g a d v a n c o d c o n c e p t s and to e v a l u a t e a t t r a c t i v e n o i n e r e d u c t i o n a p p r o a c h e s . A l s o , s t r u c t u r e b o r n e n o i s e r l u s t b e e v a l u a t e d a s i t may b e a s i g n l f i c a n c c o n t r i b u t i o n t o c a b i n n o i s e .

A f i v e y e a r r e s e a r c h program is recommended t o implement t h e d e v e l o p m e n t o f t h e a b o v e p r o p e l l e r t e e h n o l o g i c s and i n t e g r a t e them i n t o a u o e n b l e d e s i g n s y s t e m . The p r o p o s e d program i s s t r u c t u r e d t o a d v a n c o t h e v a r i o u s p r o p e l l e r t e c h n o l o p , i e s t o t h e p o i n t 02 a c c e p t a b l e r e a d i n e s s f o r commercial development by t h e end o f t h e f i v e y e a r e f f o r t . The d e t a i l s a n d time s c h e d u l e s of t h o r w e a r c h t h a t is p r o p o s e d i n e a c h t e c h n o l o g y a r e a o r e p r a s a n t e d i v i T a b l e 7.

SUMMARY OF RESULTS Advanced p r o p e l l c x t e c h r r o l o g i e s w i t h t h e potential f o r i m p r o v i n g a i r c r a f t c h a r a c t e r i s t i c s s u c h a s fuel b u r n e d , o p e r a t i n g c o s t , t l c q u t s i - t i o n c o s t , a n d g r o s u weifitit were s t u d i e d . T e c l ~ n o l o g y e l e m e n t s t h a t c o u l d i n c r e a s e p r o p e l l e r p e r f o r m a n c e and r e d u c e s o u r c e n o i s e were i d e n t i f i e d and e v a l u a t e d . Composite m a t e r i a l s s u i t a b l e f o r p r o p e l l e r b l a d e s were s e J , e c t e d and t h e i r d e s i g n and manufacturing t e c h n i q u e s w e r e i n v e s t i g a t e d . A l s o , r ~ i e t h o d s o f a s s u r i n g p r o p e l l e r b l a d e s t r u c t u r a l i n t e g r i t y w e r e a d d r e s s e d . The i n f o r m a t i o n t h u s g e n e r a t e d was combined t o d e f i n e a n "opti.mum" advanced t e c h n o l o g y p r o p e l l e r f o r e a c h o f t h e

s l r c r a f t i n c l u c \ @ d i n 1l1u s t u d y , A r \ \ i a e i o n a n n l y s i a was t h e n p e r f o r m e d t o q u a n t i f y t h e a d v a n t a g e s of tlrc) "optimum" p r o p e l l e r powered a i r c r a f t o v e r b a s o l i n e p r o p e l l c r powcrod a i r c r a f t .

P r o p a l l c r t c e h n o l o g y e l e n ~ c t ~ t r r t h a t c o u l d i n c r n a s e p e r f o r m a n c e ( 1 . e . o f f l c i o n c y ) worc i d c n t i f i a d and d i v i d e d i r l t o two c a t e g o r 3 , s s ; n o r m a l p r o p u l l e r deu-lgti v r i r i a b l e e and aclvancrd c o n c e p t s . t n c r e a s e s I n p r o p o l l a r e f f i c i e n c y were proviclad by t h e follow in^ c h a n g e e i n d e s i g n v a r i a b l e s : decreased power l o a d i ~ r g , b l a d e " h i c k n e a s r a t i o and a c t i v i t y f a c t o r ; 11116 i n c r c w s c d t l p s p e e d and number o f b l a d e s . Tho a d v a n c a d c o n c e p t s t h a t p r o v i d e d i n c r e a s e d e f f i c i e n c y were NASA p r o y l e t a , b l a d e sweep, a d v a n c e d airfoils and improved s u r f a c e i i n i a h r e s u l t i n g f r o m t h e u s e o f a d v a n c e d r o m p o a l t e m a t e r i a l s . A r e d u c t i o n of i n t e r 1 r- e n c e ibf f e c t ~ from lmprovod p r o p c l l c r / n a c e l l i * i n t e g r a t i o n a n d b e t t e r s p i n n t l r / b l a d e s h a n k 1 ) l c n d i n g i l l e o ~ I I C ~ C ~ I ; ~ p r o p e l l e r p e r f o r m a n c e .

T h e t e c h n o l o g y c l e m a n t s w i t h t h e p o t e n t i a l t o d e c r e a s e n o i s e w h i l e i n c r e a s i n g perfarmitnc-c. i n c l u d e t l i n c b r e a s i n g t h o number o f bladosr, incorporating swocp nnd r e d u c i n g t h i c k n e s s w i t h l n s t r u c k u r i 3 l limits.

H e d u c i n ~ t i p s p c c d nnd movJ;lg p e a k blntlc l o n d t i i g i n b o a r d r e d u c e d n o i s e b u r a l s o p e r f o r m a n c e . A c t i v i t y f a c t o r r e d u c t i o n s l o w e r e d n o i s e b u t c o u l d r e d u e c p e r f o r m a n c e i n c a e c s whcrc h i g h e r a c t i v i t y f a c t o r s a r e n e c d c d . NASA p r o p l e t s arrd advonccd a i r f o i l s h a v e some e m a l l p n t e i l t t a l f o r r e d u c i n g n o i s e .

F u t u r e p r o p e l l e r h Ladva c o n s t r u c t c d f r o ~ n con!lposite materials p r o m i s e p r a p a l l e r e o f l i g l l r c r w e i g h t nncl h a t t e r performarrcc w i t h l o w e r n o i s e and g r e n t c r s a fcry ~ t i l r g 1 1 \ ~ , 'I'hcref o r e , a p p r o p r i a t e c o m p o s i t e material^ w o r e scrcanctf a n d f o u r were selcctad and c v n l u a t e d : E-Glass, S - G l a s ~ , K e v l a r , and G r a p l l i t e . E-Glass anti K c v l n r n p p c a r t o b e t h o b e s t c h o i c e of m a t e r i a l s f o r tllc n e a r term. The h i g h c o s t o f G r a p h i t e would p r e c l u d e i t s u s e e x c e p t when i t s high s t r e n g t h c h a r a c t e r i s t i c s were r e q u i r e d .

A s t u d y was made oC t h e v a r i o u s c o m p o s i t e m a n u f a c t u r i n g t e c h n i q u e s t h a t were a p p l i c a b l e t o p r o p e l l e r b l a d e c o n s t r u c t i o n . Due t o t h e compound c u r v a t u r e o f advonccd p r n p r L J a r Lade c o n f i g u r a t i o n s , t h e b e s t l e a d i n g e d g c p r o t e c t ion was a f f o r d c d b y nn e r o s i o n c a p o f e l e c t r o f o m . e d n i c k e l . M a n u f o d t t t r i n g p r o c e s s e s u s i n g t a p e g o o d s i n t h e f o r m o f p r e p r e g T h r e e b l a d e mold p r o c e f i s e s and t h r e e m a t e r i a l s were c h o ~ e n n s optimum.

r o o t e n d c d n c e p t s w e r e i n v e s t i g n t c d . R e s u l t s are p r e s e n t e d a n d d i s c u s s e d .

The e t r u c r u r a l i n t e g c ? , t y of ndvnnccd t e c h n o l o g y p r o p e l l e r b l a d e s d e p e n d s o n a p r o p e r s t r u c t u r a l design t h a t c o n s i d e r 8 s t e a d y l o a d s , v i b r a t o r y f a t i g u e l i m i t u , e n ~ i n c f i r i n g s e q u e n c e , s t a l l f l u t t e r , c l a e s i c a l f l u t t e r , a n d r e s o n a n c e a v o i d a n c e . A d i s c u s s i o n o f t h e s e f a c t o r s is p r e s e n t e d . With c o m p o s j t e m a t e t i a l e , t a i l o r i n g o f t h e c o m p o s i t e m a t r i x w i l l a l l o w c o n t r o l of t h i c k n e s s , m a s s , and s t i f f n e s s d i s t r i b u t i o n t o n d e g r e e 11ot p o s s j b l e w i t h m e t a l b l a d e s . The dynamic

a n d s t r u n g t h c i ~ a r n c t c r l ~ t l c ~ s errn hc~ o p t t m t z a d t o a i l o w t h a c a n e t r u c t i o n of crdvprnced b l i i d s e Llrut tire t frlnr\c1r, knvc swctap a n d NASA p r o p l e t e , and tr lowor a c t i v i t y ftrc9tor t l m l r c ~ ~ c t o f u r e p o a 8 C b l ~ . t b w ~ v a r , t o a c l r i e v e tlraaa en&, lmyravad ael'oct l ilrr t l r 1 l e c h r \ o l o g y t s n a r a a m r y t o b a t t a r o v n l u a t e unetencly aerotlynrrinicra, f i t rzrc t u r n 1 d y n r ~ n ~ i c e , modal p r o p a l l a r l o r c o d o x c i t ion^ nncl cbvtr tl~ci t o f l u t l u r r ~ l + i k r s c t e r i e t i c e .

'I'lrc t ~ ~ i v t t ~ ~ r ~ ~ t i ~ C C * I ~ I I O I ~ g y ~ ~ r o ~ c ~ l 1 e rrj d c f 1 nuti ill t i ~ i s a t u d y hnvo composi t t * lnrrtur l n l b l n t l t ~ s R ~ C I 111t*or1wrt1tc~ U W C ~ U I ) , NASA p r o p l a t a , a n d ndvontlthd a 1 r f o l I N ; and licbtlc'rn l l y lrrrvo n l a r g e r nunrbcr of t1131r, low u c t l v l t y f c r c t o r blades. 'I'hcy arc* 1 1 t o 2 0 p c r c e l l t l i ~ h t e r tlrnn c u r r u n t tuclino l o g y p r o p r ~ l l c ~ r s . 'I'llc)y p r o v 1 tlod l t i r i t ~ s I n c r u l s c . cbf F i c i e n c y of ctbout 5 1.0 0 pc*rccstrt . 'Chc. l\in\lt\r p,ir i n s oct-urrcrd f o r t h e I r i g h c r e p ~ a d n l r r r t r f t ducb t o n r c d t r r t i o n aE t lltb I n t c ~ r f o r o n r o l o ~ t i o s w h i c h arc 1 m 8 u r n t 1\Sp,1.;~" H ~ I ~ L V ~ H .

A 1 r t - r c ~ f t wJ clr irtlvnni*c*d t c+rlrncrlouy p r o p e l l u r u u r h l f ~ v o d t h e EollowJng ~ n f n u over h n s c l ' t n o pr'q)tl 1 1 o r powc~rc*tl cl i rcrrrf t , w i t h t l o t h t h e \~clec?linq atid ~ I J V R I I C < * ~ t oc-lrno l o g y c a t l i r ~ mcc+t 1 1 1 ~ (111 FAR P a r t 36 n o i s o c o n s t r s l t i l : A l z c r a f t Put* 1 !I:IV I I I R H l'ilnflt~l ~ I ' O I I I 8 t o 10 p c r c w l t f o r tlrc. lowor spc*c*tl $\ l r r r n f L ~lntl I 4 Lo 18 pcsrcont For tha ! \ i g I ~ t ~ r c9ru l tic+ spr*c*cl n l rc3rili't , A i rc-rrtft o p c r n t in): c.clz;t .sl wc'rc* rrltlucvcd a b o u t 5 t o G pcrcc'nt t i r ~ ~ l ;I l r ( ~ t - t k f t r ( * l t ~ 1 l i \ r q u i s l t i o n c o s t s were r c t d u ~ - ~ d nhout R t o J O p c r c c n t . 'I'hc'se cotits k%ltowed u o ,ril;nlf lcrtrit t r e n d wlttr r ~ i r c r s f t t y l ~ c .

AlrCr4itf't w ~ * l p , I ~ t from rtbsi z i n g wtro r t ~ d u c e d nbaut 6 t o 10 p e r c e n t .

\Jlrc~r rrtlvirt~ccd t t ~ r l r r i o J u ~ y propo21tlr powcrod a i r c r a f t were c o n s t r a i n e d t o FAR P a r t ,'~6-5dR(B) and t-atapnrccl t o hcrscl t n t b p r o p u l l o r yowerad a i r c r a f t a t FAR Ptlrt 3 6 , t h c rthavU flnitlr; wcbrct climln~1sl1od a b o u t 1 p u r c a n t o r l o s ~ , A f i v e y u n r r s s c a r c h pruRram w t r s rornmmcndud t o Implement t h e devctlupnrent: o f c~dvnncc*d nerrudynrrnrS [,a, compr)s 1 t c tcchnol ogy , oplror;ltis t i c s , atld lmpravcd noiscl ~ ) r c t l f c t i o n tnct tlodulo&y, a n d t o i n t e g r n t e them i l l t o n usol)lc propc+l l o r t l c s t g n ~ y s t a ~ n r .

C,I:NI:HAI,X ?,I!!) PROI'EI,LEII I, I S'I' I'R LCt; I'ER POUND EQUATION [I979 L)ol l : ~ r s ) IZP = Rcl:lt ivc 1 i s t ],rice 1':lctor for v i ~ r i o u s composite materials I: = blisrc. 1 l:lnc.r>rir cxljcnsc t'i~ct or f o r cotnpnsi t c s = 1 . 2 (3) A 1 1 nan-ruvcrso, cc)urrtcrwcight ccl, ful 1 Fcn thox-i rre :)rope l 1 crs [ A ) till const:~nt sl~octl, ~~;)ut~tcrwcightctl, ft,111

f o a thcri ng , rcvcrsc prolm l l c r s

For propcl lcr tylw ( 1 ) cnt i rcly cc)~~ipos i r e , I'c - RPxPxT: For propel icr. typcs ( 2 - 4 ) w it11 composi t c hl;itlcs, 1'~: = C.55 + . & I S RP) P x I: NO'l'li: 1 : inr ludcs tool i t ~ j i ;rmort i z i ~ t ion :,nrl cngineorlalg expense itssoci:rtcd w i tll ncw techno1 ogy .

I ' and I)(: re p r i c e per1 jlo~rntl ntrnrhors which inust hc multiplicd by ttla propel l c r w c i g h t for t c~t:ll p r ~ ~ o l Icr l i s t p r i c e dct c r n ~ i n l ~ t i o n .

W p s = Propol lcr nct wc!ight , Ibs, (cxc~ludcs sl>inncr, tlcicing 6 governor) IZW I<c;l:~t ivc h l i ~ t l i . \~ciglrt f a c t o r Fol. v : ~ r t o ~ l s isoml,ositc m ; ~ r c r i ; ~ l s I ) I'l.olw 1 l c r tl i irerct c\tt, f t .

N - I)ropc\l lcr spcc.tl, IIi'Pl ( t ;!kc-clf'f'l

M =. M;r ch No. (tlcs i PI) c.oricl i t i on : rai~s , Iiorrrrjr r ~ r i s c ) KW, [ I , v i111tl y \':I l u r s for. usc itr t he\ wcigi\t ccl\r:~t i n n r ~ r c t rakcn From t a b l e bclow I'ropc l 1 u y t y prs ilssoc i n t cd w i th : ~ l ) o v ~ KIV :I lbc ;IS Fo 1 I ows :

41' 11 v Y

-.

(1) A 1 1 f ixcd 1)itch prc)ps 1 fil .!I . 33 0

( 2 ) All nan-counrcrwciglrtctl, 1ion-fcirtl1c~1.irrg, corrstnnt spootl props 200 .9 .,75 0 (33 All non-scvcrsc, r o u ~ ~ r c ~ l . w e i ~ l ~ t c t l , f11l1 fciltllcr'inji props 2 1 0 . 7 .40 3 . 5 ( 4 ) A l 1 cons t irnt sl>c*ccl, cbotln t*cr\Jc\i g11 Qctl , fir 1 I f c u r h c ~ ~ i n p , ~ scvc~.se t i ~ * o l ) s 180 $ 7 4 3 . 5 Adjustnlcnt of W I ~ f'nr ~wc)l>cl lcrs lrri 1 i z i n g coepositc nr:rtcri:lls \V(: = RW s Wfr For pr'o~c 1 1 cr t Y ~ C ( 1 ) cnt i rc l y ~~011:pns i t c ' , Fcrr ~ ' r r o l ) ~ ~ Icr typos ( 2 - 4 ) w i tll c.i?mpositc\ 11 l;ctlcs, I\'(; - ( . 4 + . 6 Rw) !Jar Whcrc RW i s ;IS j,rrclic.ntcrl I)c~Io\v:

b l a d e i3ctivit.y f a c t o r l o c a l h l n d c c h o r d , rill ( i n . ) b l a d e t j l r d i a n l a t c r , c111 ( i n . ) dB (A) A-Wei~htcid Noise l,cvcl,in l k c i b c l s , w i t 1 1 u r e f e r e n c e o f 20uPu (0.0002 clvncs/c~~u') horscpowc r advancc r a t i o , Va/nl) r o t a t i o n a l s p c c d , zcvo l u t i u n s per second power, k W ( f t- l.b/sec) b l a d e t i p r t ~ I l u s , cm ( i n . ) r r a d i u s , cm ( i n . ) SHP s h a f t power, kW ( h p ) T t h r u s t , N(l1)) t l o c a l b l a d e t h i c k n e s s , c ~ n ( i t r . ) TAF t o t a l a c t i v i t y f a c t o r = b l a d e a c t i v i t y f a c t o r X number of b l a d e s Eree-atrcam v e l o c i t y , m / s w ( E t l s e c ) change i d e a l propu1.sive e f f icic.ncy = ( T i d e a l v,) /P (excludes b l a d e p r o E i l e d r a g and c o n l p r e s s i b i l i t y l o s s e s ) e f f i c . 2 e n c y = ( T V , ) / P f r e e - s t r e e m d e n s i t y , kj:/m3 ( s l u g s / f t 3 )

REFERENCES 1. L. J. Williams and T. L. Calloway, "Design for Supercormnutera."

Astronautics and Aeronautics, Vol.19,No. 2, pp. 201-30, Feb. 1981.

2. Anonymous, "SBAC-Standard Method of Propeller Performance Estimation." Society of British Aircraft Constructors, Ltd., April 1950.

3. J. P. Sullivan, L. K. Chang and C. J. Miller, "The Effect of Proplets and Bi-Blades on the Performance and Noise of Propellers."

SAE Paper 810600, SAE Business Aircraft Meeting and Exposition, April 1981.

4. S. Coldstein, "On the Vortex Theory of Screw Propellers."

Royal Society (London) Proc., 1929.

5. C. N. H. Locke, "Application of Goldstein's Airscrew Theory to Design." British ARC, R&M No. 1377, Nov. 1930.

6 S. F. Hoerner, "Fluid Dynamic Drag." 1965.

7. Henry V. Borst, "Summary of Propeller Design Procedures and Data." Vol. I, Aerodynamtc Design and Installation, USAAMRDL Tech Report 73-34A.

8. J. L. Hess and A . M. 0. Smith, "Calculation of Potential Flow About Arbitrary Bodies." Pr,ogress in Aeronautical Sciences, Vol.

8, pp. 1-138, 1967.

9. R. J. Jeracki and G. A. Mitchell, "Low and High Speed

Propellers for General Aviation - Performance Potential and Recent

Wind Tunnel Test Results." SAE Paper 310601, SAE Business Aircraft Meeting and Exposition, April 1981.

10. G. R. Reid, "Studies of Blade Shank Form an<] Pitch Distribution for Constant Speed Propellers." NACA TN 947, 1945.

11. J. D. Maynard, "Aerodynamic Characteristics at High Speeds of Full Scale Propellers Having Different Shank Designs." NACA RML6L27a, 1947.

12. F. B. Metzger and C. Rohrbach, "Aero-Acoustic Defrign of the Prop-Fan." AIAA 79-0610, 1979.

13. J. F. Dugan, Jr., B.S. Gatzen and \I. M. Adamson, "Prop-Fan

Propulsion - Its Status and Potential." SAE Paper 780995, SAE Aero-

Space Meeting, San Dicgo, Gal., :lovernhcr 1979.

14. R, J. Klatte and F. B. Metzger, "Influence of Noise Reduction on Weight and Cost of General Aviation Propellers." FAA Report

HEFEKBNCBS No. FAA-AEE-79-18, J u n e 1979.

1 5 . A. .I. B o c c i , "A Ncw S c r i e s of AeroPoiL S e c t i o n s S u i t a b l e f o r A i r c r a f t P r o p e l lers." A c r a n n i l t i c t ~ l Q u a r t e r l y , Vol. 28, P a r t 1, pp. 59-73, F e b r u a r y 2977.

I h . S. F. t30crner iind H. V . I l o r s t , " F l u i d Dynamic L i f t . " 1975.

17. W . A. S t e v e n s , S. H . Gorndln and J . A. Rraden, "Mathematical Model f o r Two-I)imct~sionnI hlult i-Component: A i r f o i l s i n Viscotls Plow."

NASA CR-1843, J u l y 1971.

18. C. J . Woen atld C . M . Grcgorck, "Thc. Bxnrt N i ~ m e r i c n l C t i l c u l a t i o n o f P r o p c l l o r N a i s r . " A I M Pnpcr 78-1522, AIM 1 1 t h Flrlid tlnd Plastt~n Ilynr~rnics C a n f c r c n c c , S c o t t l.u, Was'tlirrgton, J u l y 1978, 19. K. D. Korknn, C. El. Crc!gorck and 1, K o i e e r , "An A c o u s t i c S e n s t t 4 v i t y S t u d y o f Gencrnl Avi:ztlon P r c r p e l l e r s . " A S M Pnper 80-1871, AZAA A i r c r a f t : Systcms Plcctiog, August 1980.

20. &orfie P . S u c c i , "l)esign o f ISuiet: EFEicienE P r o p c l l e r s . " SAE Pnper 790584, SAE H i l s tnc!sa h l r u r n f r blc.etiug, W i c h i t u , Ks., A p r i l 1979.

2 1 . 1. H . A b h s t t and A . R . Von I) w n h o f f , "Tlreory of Wing Scct:ions. " Oovcrr I3tlhl.Ic-n t i n n s , N o w York, 1 9 4 9 .

Sea Lcval 1)os I k:i~tl t ~ ( > I I C r t ~ i a c ~ Spectd S t a t i c Power

.-.. . * . - a - , ~l\/?;cc - ------. knot^) * kW (hp)

S i n & l o Rcc iprocnt i t r ~ ICnginc 'rw l u Rccipros%at 1 ng Eng i nc Twin 'I'rtrhoprop Ci'~~ili1 148.3 (288) 820.3 (1100) 1 ') P A S S'l'hl' (Rcf. I )

TABLE 2. - CURRENT TECHNOLOGY PROPELLER CHARACTERISTICS

A i r c r a f t 19 PAX Engine Lycomi ng Continental Continental A i research Continental P r a t t & Whi tney 0-320-H2AD 10-520-L TS 10-520-NB TPE331-8-403s 10-520-D PT65 Series Shaft Power, k W (hp) 119.3 (160) 212.5 (285) 231.2 (310) 473.5 (635) RPM ' Propel 1er Model Diameter, rn ( i n ) 1.91 (75) 2.03 (89) 1.94 (76.5) 2.29 (90) 2.79 (110) Number o f Blades 2 3 3 3 3 T i p Speed, rnlsec ( f t / s e c ) 269.7 (885) 287.1 (942) 274.6 (901) 239.3 (785) 248.7 (816) Total A c t i v i z y Factor 170 243 267 390 360 I

i t / b @ 314 R. .085 .081 -083

.065 .om .063

E A i r f o i 1 Type RAF-6 CLARK Y RA F- 6 16-64 Series RAF- 6 16-64 Series !

T i p Sweep 0" 0" 0" 1" .5O Proplets None None None None None None Weight, kg (lbm) 16.2 (35.8j 30.8 (68.0) 31.8 (70.2) 52.9 (116.6) 29.5 (65.0) 75.4 (166.2) **Cost (1979 $ ) $704 $1814 $2098 $4715 $1734 $6721 Materi a1 a1 umi num aluminum a1 umi num a1 umi num a1 umi nun * Note: Weight includes hub, blades, and controls.

** Note: C ~ s t i s r e t a i l l i s t .

- .

TABLE 3 . - TECHNOLOGY ELEMENTS AFFECTING PERFORMANCE

P e r f o r m a n c e Loss R e f e r e n c e Technology E l e m e n t To Be Minimized U t i l i z e d I n d u c e d D e c r e a s e d power l o a d i n g A x i a l momentum T i p s p e e d T i p a n d s w i r l I n c r e a s e d number o f b l a d e s T i p NASA p r o p l e t s T i p B l a d e Drag Sweep ( r e d u c e d h e l i c a l t i p C o m p r e s s i b i l i t y Mach number) C o m p r e s s i b i l i t y , Advanced t e c h n o l o g y a i r f o i l p r o f i l e d r a g C o m p r e s s i b i l i t y , D e c r e a s e d t h i c k n e s s r a t i o p r o f i l e d r a g Improved s u r f a c e f i n i s h F r i c t i o n d r a g D e c r e a s e d a c t i v i t y f a c t o r P r o f i l e d r a g I n t e r f e r e n c e Improved p r o p e l l e r / n a c e l l e B l a d e d r a g , n a c e l l e d r a g 4 , 5, 8 i n t e g r a t i o n B l a d e d r a g , i n t e r f e r e n c e S p i n n e r / b l a d e s h a n k d r a g 6 , 9 b l e n d i n g

TABLE 4. - TECHNOLOGY ELEMENTS AFFECTING ACOUSTICS

T e c h n o l o g y Element R e f e r e n c e U t i l i z e d I n c r e a s e d number of b l a d e s D e c r e a s e d t i p s p e e d D e c r e a s e d activity f a c t o r P r o p l e ts P e a k b l a d e l o a d i n g moved i n b o a r d Sweep Advanced t e c a n o l o g y a i r f o i l s D e c r e a s e d t h i c k n e s s r a t i o

TABLE 5. - ADVANCED TECHNOLOGY PROPELLER CHARACTERISTICS

A i r c r a f t 210M 4 14A A188B 19 PAX *Shaft Power, k W (hp) 201.3 (270) 193.9 (260) 205.1 (275) 801.6 (1075) "9PM 2653 2699 2653 18 18 + i p Speed, m/sec ( f t / s e c ) 317.6 (1042) 305.1 (1001) 317 - 6 (1042) 290.2 (952) **Shaft Power, k W (hp) 202.8 (272) 196.1 (263) 207 - 3 (278) 805.4 (10%) **RPM 2429 2399 1627 **Ti p Speed, m/sec (ft/sec) 287.1 (942) 274.6 (901) 287.1 (942) 259.7 ( 852) 2.29 (96) 2.16 (85) Diameter, m ( i n ) 2.29 (93) 3.05 (120 ) Number o f Blades 4 4 5 267 390 240 360 Total A c t i v i t y Factor 243 t / b @ 314 R. .060 -063 .040 .060 .OM A i r f o i l Type Advanced Advanced Advanced Advanced Advanced Advanced T i p Sweep 25" 25" 25" 25" 25" ***Prop1 e t s 5% h/R 5% h/R 5% h/R 51 h/R 5% h/R ***Weight, kg (lbm) 25.1 (55.3) 27.0 (59.6) 45.0 (99.1) 21.9 (48.2) 57.7 (327.2) $900 $2406 $2854 $6169 $2045 $8777 E-Gl ass Kev;ar Kevlar Kevl a r Kevlar Kevl a r Note: S a t i s f y i n g FAR P a r t 36.

* Note: S a t i s f y i n g FAR P a r t 36-5dB(A).

*** Note: h/R i s p r o p l e t height t o blade radius r a t i o .

*** Note: Weight includes hub, blades , and control s .

i I **** Note: Cost i s r e t a i l l i s t .

TABLE 6. - CURRENT AIRCRAFT STATISTICS

; A I R C W F T 19 PAX i FUEL BURNED, k g (lbm)

1 2 H o u r C r u i s e

CRUISING ALTITUDE, m (ft) CRUISING POWER P e r c e n t o f Max Power t [ MAXIMUM CONTINUOUS SHAFT POkiER, k W (hp) RPM

1 CRUISING SPEED, m/sec ( k n o t s )

SFC a2 CRUISE ( p e r e n g f i ~ e ) kg/kW-hr (1Sm/hp-hr) PRICE GNEQUIPPED ( 1 9 7 9 $) EMPTY WT, k g ( l b m ) TAKEOFF GROSS i' VI

Table 7 - S c h e d u l e for P r o p o s e d R s s e a r c h P r o g r a m

- - --- - - - -- - - - - -

ADVANCED CONCEPTS AND TECHNOLOGY EVALUATION Y E A R

AERODYNAMICS -AIRFOIL TECHNOLOGY DEVELOPMENT -PROPELLER / NACELLE INTERACTIVE ANALYSIS -SPINNER / BLADE SHANK INTERACTIVE ANALYSIS -IMPROVED AEROWNAMIC PERFORMANCE ANALYSIS -WIND TUNNEL TESTING -FULL SCALE DESIGN, FABRICATION AND TEST lNG COMPOSITES *IMPROVED A h A LYSlS CAPABILITIES *DESIGN CONCEPTS 0 0 'MANUFACTURING, TOOLING AND PROCESS DEVELOP M E N 1

- z!

0 0 0 r2 -FULL SCALE DESIGN

0 5

-FULL SCALE FA6alCAT ION AND FLIGHT T €STING r f "t 7: P L I 3 AEROELASTICS i-;

-IMPROVED VIBRATORY STRESS PREDICTION METHODOWGY ZZ

NOISE -IMPROVED NOISE PREDICTION METHODOLOGY DESIGN OPTIMIZATION -Am0 /ACOUSTICS .COMPOSITE STRUCTURES FLIGHT VERIFICATION -PERFORMANCE, NOISE AND STRUCTURAL INTEGRITY

K' +.-

IDENTIFY ADVANCED TECHNOLOGIES

C Z 7 3s .- T i : 3 .r 4 . . :

ASSESS BENEFITS, COSTS 1 RISKS

DEFINE OPTIMUM CONFIG., MISSION ANALYSIS

RECOMMEND TECHNOLOGY PROGRAM

W a Figure I. - Advanced technology propeller study.

McCAULEY PROGRAM MANAGEMENT, PERFORMANCE, COST, STRUCTURES a CESSNA AIRPLANE MISSION ANALYSIS OH10 STATE ACOUSTiCS MATERIALS SCIENCES & SAi COMPOSITES Figure 2 . - Team comprising study effort.

CESSNA 210M CESSNA Ai88B STAT CESSNA 441 CESSNA 414A Figure 3.- Baselir;.~ aircraft studied.

TIP DEVICES INTEGRATION I NTEGRATED BLADEISPINNER Figure4. - Advanced technology concepts.

ORIGINAL E%,':i:Sti 5f.f OF POOH QUALITY

i. \\ AXIAL MOMENTUM LOSS I

MOM, THEORY ap BLADES 8 BLADES 5 BLADES 2 BLADES POWER LOADING S H P ~ k ~ / d 1 I 1 t k 0 5 1 0 1 5 20 POWER LOADING SWP/D: hp/tt2

(a) Airspeed, 26 m/sec. (50knots)

Figure 5.- E f f e c t of power loading and number

of blades on induced efficiency:

274 m/sec. ( 9 0 0 f t / s e c . ) tip speed

a t sea level standard conditions.

MOM. THEORY 0 BLADES 5 BLADES 2 BLADES POWER LOADING SHP/D: k w/m2 1 I 1 a 1 0 5 1 0 1 5 POWER LnADING SHP/D', h p/t t'

(b Airspeed, 7 7 m/sec. (150 knots)

Figure 4.- Continued

-' ..- - -

INTUM LOSS POWER LOADING SWP/D: kw/rn2 L 1 0 5 1 0 1 5 20 POWER LOADING SHP/D: h p / f t 2 ( c ) Airspeed, 154 m/sec. (300 knots) Figure 5.- Concluded

- 274 m/sec, (900ft/sec.) TIP SPEED

---

152 m/sec. (5OOf t/src.) TIP SPEED ORIGINAL PACE I S OF POOR QUALITY I54 m/s8c.(300knots) 77 m/sec,(ESO knots) 100 150 0 50 POWER LOADING SHP/ 0: kW/m I 1 1 1 I 0 5 1 0 1 5 20 POWER LOADING SHP/D~ hp/ft2 (a) 2 Bladed Propellers Figure 6.- E f f e c t of power loading, tip speed and airspeed on induced efficiency at sea level standard conditions.

77 rn/sec3 ( 150 knots) , I I 1 b 0 5 I0

L 5

POWER LOADING SHP/D, hp/tt2 (b) 5 Bladed Propellers Figure 6.- Continued

ORlGlNAL PAGE 1 S

- 274 rn/sec.(900tt/sec) TIP SPEED

OF POOR QUALITY

--- 152 rn/rec.(5OOtthec.) TIP SPEED

50 knots 1

I

\ ' a - \ I 1 I

I

0 50 100 'Po

POWER LOADING SHP/D: k ~ / m 1 I I 1 15 20 Q 5 I0 POWER LOAD1 NG SHP/D: h p / f t 2 (c) 8 Bladed Propellers Figure 6.- Continued

- 274 m/sec. (900 f t/sec.) TIP SPEED

-- ~52m/sec.(500fr/src.)TlP SPEED ORIGINAL BAG; i'n

OF POOR QUALI'IY All

- -- -

- (300 k"OtS)

1 I

I I

0 5 0 I00 '?O POWER LOADING SHP/D', k ~ / m I 1 L I 2 0 0 5 1 0

- ''5

POWER LOADING SHP/D, h p / f t 2 (dl Infinite Bladed Propeller

Figure 6.- Concluded

EFFICIENCY GAIN, b)L, PERCENT

REDUCTION IN THICKNESS RATIO LIT 3/4 BLADE RADIUS Figure 9.- Efficiency gain through reduction in thickness ratio.

POWER COEFFICIENT, CP Figure 10.- Optimum total activity factor for given design advance r a t i o and power coefficient.

0 . I .2 . 3 .4 .5 BODY TO PROPELLER DIAMETER RATIO, 30,Scm (12in) AFT OF PROPELLER PLANE OF ROTATION.

Figure 1 1 . - Efficiency loss due to body blockage.

-

4 -

NOTE : GAINS POSSIBLE ASSUME

75% REDUCTION IN INTERFERENCE DRAG AND 3 - MAINTAINING O F AIRFOIL

e

a SHAPE INTO SPINNER a CUFF.

z

-

u

(3

-

t Z W

-

C ) i i LL

* I -

I ,4 AIRCRAFT MACH NUMBER

Figure 1 2 .- Ef f icisncy gains t hrouyh reduct ion

in spinner/shank interference drag.

ORIGiNhL E.Y;:Gf: IS OF POOR QUALITY NUMBER OF BLADES Figure 13.- Noise reduction through increase in number of blades.

0 .01 .02 .O 3 .04 .05 REDUCTION IN THICKNESS TO CHORD RATIO AT .75 RADIUS Figure 15.- Noise decrease through reduction, in blade thickness,

- TIP SPEED DECREASE, f t / s e c .

Figure 16.- Noise reduction with tip speed decrease.

4~ ORIGINAL PAQE IS OF POOR QUALITY 3 - n

a

Y m u *

-

W V) 2 Q W & W t3 W V) .-

z

- I

0 0, I 0.2 0.3

INBOARD SHIFT OF PEAK LOADING P O S I T I O N , A r/R

Figure 17. - Noise decrease with inboard shift

of peak loading.

0 0.1 0.2 0.3 0.4 0 . 5 INBOARD SHIFT OF PEAK LOADING POSITION, Ar/R Figure 18.- Efficiency loss with inboard shift o f peak l o a d i n g .

ORIGiNil; OF POOR (IUALI? Y 5 1 0 1 5 20 ACTIVITY FACTOR REDUCTION, PERCENT

Figure 1 9 . - Noise reduction through reduction in

activity factor.

COMPOSITE PROPELLER BENEFITS ADVANTAGES LOWER WEIGHT IMPROVED PERFORMANCE LOWER DENSITY LOWER NOISE HIGHER MODULUS ENHANCED SAFETY LOWER NOTCH MARGIN SENSITIVITY b Figure 20.- Benefits of composite materials.

k * a O 1 MATERIAL COST

1 . ~ 1 1 MANUFACTURING COST

E-GLASS S-GLASS KEVLAR GRAPHITE ALUM.

Figure 2 1 . - Blade weight and cost comparison.

-1

( A ) Aerodynamic (B) Structural Design ( C ) Environmental diameter frequencies erosion chord materials lightening planform fatigue life repairability twist ultimqte strength c r o s s sectisn r o o t end attachment balmce manufacturing process c o s t Figure 22.- Design criteria.

SECTION FREQUENCIES PROPERTIES I , ., A CRITERIA - LOADS STRESS ANALYSIS > Figure 23.- Iterative process to assure blade structural adequacy.

PRECURED WEB / ' - I

I

/

PRECURED TRAlL'PJG 7 LEADING EDGE HAiF EDGE CAP

/

TRAILING EDGE HALF EROSION CAP I L ~ - ~ ~ ~ SKIN Figure 24.- Precured Leading and Trailing Halves.

FOAM CORE Y-

*-- X-PLY OVERLAP

/

I I L - X - PLY SKIN PRECURED TRAILING EDGE CAP Figure 25.- Foam Core

LEADING EDGE EROSION PRECURED 3PPER SPAR \AP (UNI)

k - + X- PLY OVERLAP

x PLY SKIN

I PRECUREO TRAILING EDGE CAP Figure 26.- Pcec1,rred Upper and Lower Spars.

ALUMINUM SLEEVE Figure 2 7 . - Coke Bottle Root End.

FILAMENT WINDING

\

Figure 28.- Hybrid Root End.

FILAMENT WINblNG ,COMPOSITE MANDREL Figure 29.- All Composite Root End.

CESSNA 210M

CESSNA A188B

CESSNA 172N

2 i o ,-

l o r

lo r

! z B BLADE

INTER- - - - - - - CRAG FEREWCE DRAG FERENCE DRAG FERENCE - TOTAL TOTAL TOTAL

CESSNA 441

CESSNA 414 A

r

8.9 c--- 1 INDUCED BLADE INTER- INDUCED BLADE INTER- DRAG FERENCE DRAG FERENCE TQTAL TOTAL F A R 3 8 .

--- -- BOTH BASELINE AND E.t)VAWCED CONFlGCZRAT1ONS MEET

- BASELINE MEETS F h R 3 6 ; ADVANCED CONFIGURATIONS MEET FAR36-SdB(L).

Figure 30.- Potential cruise performance gains, two hour cruisr

mission.

CESSNA 210 M

CESSNA A1886

CESSNA 172 N

5 r

r

r

% 0 0 C 4)

-- I

5 I

-

-

-

r r rt cC -

'DO

SPINNER TOTAL NAC ELL€

' O NACELLE SPlNN

/BLADE BLOCKAGE: BLOCKAGE /BLADE BLOCKAGE /BLADE SHANK SHANK SHANK ff FECTS E f FECTS EFFECTS

1 9 P A X . STAT g$

CESSNA 441

5 r

SHANK SHANK EFFECTS EFFECTS Figure 31. - Potential performance gains from interference eft ects.

R A T E D S H A F T TAKEOFF GROSS WEIGHT ( I b m i P O W E R (shp) T A K E O F F GROSS R A T E D SHAFT P O W E R ( k w ) WEIGHT ( k g )

TAKEOFF C R O S S T A K E O F F GROSS R A T E D S H A F T RATED S H A F T WEIGHT (Ibm) WEIGHT (Ibm) POWER (shp) POWER Ishp) W W W

P m Q )

0 0 0 0 0 0

-

T A K E O F F GROSS T A K E O F F GROSS R A T E D SHAFT R A T E D S H A F T WEIGHT ( k g ) WEIGHT ( k g ) POWER (kw) POWER ( k w )

T A K E O F F G R O S S R A T E D SHAFT R A T E D S H A F T T A K E O F F GROSS WEIGHT (Ibm) P O W E R (shp) POWER (shp) WEIGHT (Ibm) W ( D ( D h ) O d , O ) C n U I a m O ) N U 4 0 h ) 0 0 0 0

< J I o a o u

0 0 0 0

. w

w rn R A T E D SHAFT RATED SHAFT T A K E O F F G R O S S TAKEOFF GROSS P O W E R (kw) FOWER ( k w ) W E I G H T ( k s ) W E I G H T (kg)

STAT BASELINE- CURRENT TECHNOLOGY B E z % g MEETING FAR 36 Q w C B CRUISE SPEED (m/sec.)

CRUISE SPEED (knots) Figure 33 .- Potential trip fuel savings.

O FAR 3 6 - 5 d B A

a

z

STAT BASELINE -CURRENT TECHNOLOGY MEETING FAR36 CRUISE SPEED(m/sec.)

CRUISE SPEED (knots) Figure34. - Potential operating cost reduction.

FAR 36 O FAR 36-5dBA STAT BASELINE-CURRENT TECHNOLOGY MEETING FAR 36 CRUISE SPEED (m/ sec. ) CRUISE SPEED (knots) Figure 35.- Potential aircraft retail cost reduction.

STAT F A R 3 6 0 FAR 3 6 S d B A BASELINE-CURRENT TECHNOLOGY MEETING F A R 3 6 CRUSE SPEED (m/ssc.)

CRUISE SPEED [knots) Figure 36.- Potential gross weight reduction.

" TECHNOLOGY DEVELOPMENT AERODYNAMICS ACOUSTICS A E R O E L A S T I C S COMPOSITES a TECHNOLOGY INTEGRATION VERIFICATION Figure 37- Recommended technology program.