Wind-Tunnel Investigation of Air Inlet and Outlet Openings for Aircraft, Special Report

VIlTD-T3Bl?EL IBVESTIGATION OF A I R XNZET ABD OUTLET OPEZINGS FOR AIRCRAFT B y FrancLs Id. R o g a l l o and V i l l i a m 3 . Gauvain An i n p e s t i g a t i o n m a s made i n t h e B.A.C.A. 5 - f o o t v e r - t i c a l mind t u n n e l of a l a r g e v a r i e t y of d u c t i n l e t s and o u t l e t s t o o b t a i n i n f o r n a t i o n r e l a t i v e t o t h e i r d e s i g n f o r t h e c o o l i n g o r t h e v e n t i l a t i o n s y s t e m s on c i r c s a f t . !dost of t h e t e s t s a e r e of o ~ e n i n g s i n a f l a t p l a t e b u t , i n or- d e r t o d e t e r m i ~ ~ e t h e b e s t l o c n t i o n s a n d t h e e f f e c t s of i n t e r f e r e n c e , a few t e s t s mere nade of o p c a i r g s i n a n a i r - f o i l .

The S e s t i n l e t l o c a t i o n f o r n s g s t e n n o t i n c l u d i n g a blo-or was found t o be a t t h e f o r w a r d s t a g n a t i o n p o i n t ; f o r one i a c l u d i u g a b l o n e r , t h e b e s t l o c a t i o n was found t o be i n t h e r e g i o n of l o n q s t t o t a l h c a & , p r o b a b l y i n t h e 5oundary l a y e r n e a r t L e t r a i l i n g edge.

Design fecomrnendations a r e g i v e n , and i t i s shown t h a t c o r r e c t d e s i g n demands a knowledge of t h e e x t e r n a l f l o n aad. of t h e i n t e r n a l r e q u i r e m e n t s i n a d d i t i o n t o t h a t o'atalned from t h e r e s u l t s of t h e wind-tunnel t c s t s .

Scoops a n d v e n t s o l many t y p e s a r e i n g e n e r a l use on e v e r y a i r p l a n e f o r p u r p o s e s of u t i l i z i n g a i r f l o w , such a s : du-cted c o o l i n g ; c a 3 i n v e n t i l a t i o n ; c a r b u r e t o r i n t a k t ; e n g i n e e x h a u s t ; and b a t t e r y , g a s fank, a n d f l o a t v e n t s .

I n f o r m a t i o n n e c e s s a r y f o r t 3 e d e t e r m i n a t i o n of t h e most e f f i c i e n t s h a p e s a n d l o c a t i o n s a a d f o r t h e d e s i g n of p a r - t i c u l a r i n s t a l l a t i o n s h a s , however, been laclcing. To moct t h i s n z e d , t h e R . A . C . A . u n d e r t o o k a n e s p e r i n e n t a L i n v c s - t i g a t l o n of t h e o p e n i n g s of induced-flow systems.

Iii t h i s i n v e s t i g a t i o n , <i g r e a t number o f o p e n i n g s i n n f l a t p l a t e and a few i n ail 17.A.C . A . 0018 wing s e c t i o n were f c s . t e d . The t e s t c o n d i t i o n s a n d t h c models were sys- t o r i a t i c a l l y v a r i e d so t h a t t h e r e s u l t s would i n d i c a t e tile e f f e c t s o f : a i n d v e l o c i t y ; s i z e , s h a p e , a n d l o c a t i o n of o p e n i n g s ; l e n g t h a n d a n g l e of d u c t s ; i n t e r f e r e n c e between a n o p e n i n g and a body, znd between i n l e t a n d o u t l e t open- i n g s iil t h e same 306y.

T h e o r e t i c a l c b a r a c t c r i n t i c s of i n l e t c n d o u t l e t opcn- i n g s have p r e v i o u s l y b c c ~ l d e t c r n i n c d nnd a r e u s e f u l a s a n i n d i c a t i o n o f t r e n d s alzd as a n a i d i n t h o correlation and e x p l a x a t i o n of experir.enta2. d a t a . Bac~,use of t h e n e c e s s i t ~ o f s i m p l i f y i n g a n s u ~ ? p t i o r z s , h o n e v e r , 3 i e o r e t i c a l r e snu.lt s a r e o f t e n i n s i ~ i f i c i e l t a s desigii i n f o r n a t f o n a n d . a u n t be supplemented by e m p i r i c a l d a t a . I11 1936 2okus alid T r o l l e r ( r e f e r e n c e 1) p u b l i s h e d t h e r e q u l t s of a f e n t e s t s of 0 2 ~ 2 - iizgs i n a f l a t g l a t e . SOIJC o f t h e publ.ished d r a g c 7 1 r r c s , p a r t i c u l a r l y t h o sc f o r t:;e convent iolzal-type s c o o p s rritli a n d 1 - ~ i t h o u t f a i r i n g , $-o ::lot a;;rcc v e r y n e l l n i t h t h e o r y o r a i t b 3 . A . C . A . t e s t r e s u - l t s. Xeasons f o r t h e d i s a g r o c n e n t lzavc ~ o t becn determined..

A 1 1 t!le t e s t s :?ere ~c~'T7.e i l l t h c 5 - f o o t v e r t i c a l r-rind t u ~ n c l of t h c T?,A.C.A., nhZcli i s c l ~ s c r i ' o e ? ~ i n r e f e r c a c e 2.

A s s'.or?:i i n f i g u r o 1, a ,"'.at p ' t s e l nar, p l a c e d u y r i g h t be- tmccn t h e o n t r n ~ c c ~ Z C J . t h e e x i t c o n e s , ~ r o j e c t i n g a j o u t 1 2 i n c h c s be;ond t h c s t ~ ~ c a l 01: cac3. s i d e . "he f r o n t f a c e o f t h e !?anel tras v e r t i c a l 1% i n c l i e s f r o n tlie e?ge o f t h e e x i t c o ~ e and n a s s n o o t h l y f a i r c d i n t o t h c e n t r a z c c cone a t t h e t o p . 1-9 a t t e m p t v a s riaC.c t o f a i r t 5 e d o ~ r l z t r c a n cage of tlic p c n c l i n t o t h e e x i t cone, b u t tlie opcliing b e l ~ i s d t h e p a n e l n a s b l o c k e d o f f t o p r e v e n t s t r a g a i r c u r r e n t s f r o n a f f c c t . i i i z t h e firag readings.

Static and dgnan5c-i>ressllre s-ar-;cgs v e r e nace i n t h e n o d i f i e d j e t a n d t h c t u n n e l c a l . i b r a t ; i o n f o r a l l t e s t s mas b a s e d on t h e r e s u l t s o f t h e s e s u r v e y s . A d d i t i o n o f t h e plaxte had l i t t l c e ' f c c t upon e i t h c r t k e s t c t i c - p r e s s l r e g r a d i e n t o r t h e v e l o c i t i r ; . r n J i e n t , e x c e p t i n t h e r e s i o n n e a r t h e p l a n e . T5e v a r i a t i o n of s e l o c i t y o v e r t h e mount- i n g p l a t e o n t t o a d i s e n r c e of n o r e t h a l 1 2 i n c h e s ;7as onxy 1.0 p e r q e n t of t h e zvern;e v e l o c i t y , e x c e p t i n q t h e boundary l a g e r , -::hick i s s e p a r ~ ~ t e l y t r e a t e d .

T5e c e n t e r l i n e of o p e n i n g s f o r t h e n i i g n o d e l c a s 1 8 i n c h e s f r o n t h e p l a n e , a r e g i o n l i t t l e a P f e c t c d by t h e p l a n e . The normal v e r t i c a l s t a t i c - p r e s s u r e 2nd v e l o c i t y v a r i z t i o n s of t h i s s n a l l t u n n e l o v e r a 3-foot I e z g t h ( t h e c h o r d of t h e v i n g u s e d ) v e r e nbout 6 p c r c e n t a n d 3 p e r c e n t , s p c c t i v e l y , of t h e a v e r a g e v s l u e s.

I n o r d c r t o ~ e 2 ; r c s e : l t t h c condi.tio;l of f 2 . o ~ t h r o u g h ; z l o p e n i n g i a t o o r o u t 0 2 a l a r g e c k a n b e r , s u c h a s t h e in- t e r l o r of a wlng o r a f u s e l a 3 e , tile set-7s.p c o ~ ~ ~ p r i s e d a box whose i n s i d e ? L i ~ e n o i o n s were 1 G by 1 6 b77 20 i n c h e s 2 n d m?.lose f r o n t f a c e n a s t h e f l - o a t i n g r?ou-atfng p l a t e shown iz f i 2 ; u r e 1. T':le d u c t conno ctin;; t'nis box n i t h - t h e blont2r and t h e flowr;2etcr mas a t t a c h e d t o i t s r o a r f a c e , a s slnonn i : ~ f i g n r c : 2. I f t h e u n a b s t r t t c t e d j e t f r o n t h t s ,:luct !la5 bcon a l l o w e d D o i r n ~ i r - z e upon tP:c ?roil% i i ~ s i d e f a c e of t i c box durj-izg o u t l e t t e s t s , t L e r e s u l t i n s f l o w v o u l d n o t k a v e r c p ~ c s o n t e d t k c d e s i r e d c o n d i t , i o n o f ?.miform a p p r o a c h ve- l o c i t y . A s e e t , i o n o f 15-mesh s c r e e n was t h e r e f o r e p l a c e d a b o u t 2 i n c h e s f r o m t h e r e a r e n d o f t h e box a n d a r r a c g e d - i n s u c h aLmgilner t h a t t h e f l o w o u t of t h e box w i t h t h e f r o n t f a c e removod mas f a i r l ; u n i f o r m . D u r i n g t e s t s , t h e s t a t i c p r e s s u r e i n t h e box was m.easured by a f l u s h t a p i i l t h e c e n t e r of t h e t o p f a c e .

I n o r d e r t o r e p r e s e n t t h e c o n d i t i o n of f l o w i a t o o r o u t o f EL^? o p e n i n g a t t a c h e d t o a s t r a i g h t d u c t w i t h u n i f o r m c r o s s s e c t i o c of area aBout e q u a l t o t h a t o f t h e o p e n i n g , a s , f o r example, a c a r b u r e t o r scoop o r zn e n g i n e - e x h a u s t s y s t e m , a s k o r t l e n g t h o f ducS 7 r i t C a b c l l n o u t b e l l t r y was u s c d . ( s e e Ytgs. 2 anCL 3.) End a coxttii:.uous d u c t h e a a u s e d , Z t would. h a v e i n c r e a s e r 2 t h e model-instnlla";.on, d i f - f i c u l t i e s , c s p e c i n l l g ~ 5 t h d.ucts at> a2 ~ n g ? - e of l e s s thar?

90' t o t h c f r o n t f a c e . S e o c r n l f l u s h t z p s mere i i i s t a l l e d .

iil t h e ?.uc.FY ( s e e f i g . 3) t o o b t a i n s t a t i c - p r e s s u r e d a t a . ' The c i r c u l a r d u c t a n d ' u e l l n o u t h shown ?.n f i g u r e 3 merz de- t a c i l a b l o and mere u.sed. .j.n a l l t 3 0 t e s t s ~liit::~ c i r c u l a r d u c t s . A rectangular ? . v e t ar.(l. b e l l m o u t h v e r s user! i n a l l thc: t e s t s of r e c e s s - t ~ p e i117,ets and o u t l . e t s . U ~ C c f t h e b c l l m o u t h e n t r i e s p r c v c a t e d e n t r a n c e c o n d i t i o l i s f r o ~ n af- f e c t i 3 g t h e f l o w p a t t e r n at t h e o u t l e t end d . u r i n g t e s t s o f o u t l e t o p e n i n g s .

Tl2.e c e z t r i f u g a l 31-ower ( s e e f i g s . 2 and 4) aas d r i v e n by a v a r i a b l e - s p e e d r l - i r e c t - c u r r e n t ~ o C o r a n d mas c a p a b l e o f d o u c l o p i n g a p r e s s u r e r i s e 2.f' 20 i n c h e s o f m a t e r a t a f i o m r a t e of 500 c u h i c f e e t p e r ~ : : i n u t e . T h e c a s e mas a i r - t i t , s k a f t c l e a r a ~ l c e bei3.g s e n l e d bg an o i l r e s e r v o i r betmccc two r e t a i n e r s .

T h e o r i f i c e drum ( f i g s . 2 and 4) was r-mde of a n o i l drum n p p r o x i n . z t e l y 2 3 i n c h e s i n 2 i a n e t e r czilcl 35 I n c h e s h i g h , a n d t h e s i x s h a r p - e d g e o r i f i & e s o f d i r r ~ e t e r s f r o m 1 t o 4 i n c h e s mere b o r e d i n b r a s s p l a t c s 1 0 i n c n e s s q i l a r c and 1 / 8 - ? - n c \ t h i c k . Thc o r i f i c e s mere c r l i b r a t c d o v e r 2 g r e z - s u r e r a n g c of 0 t o '$0 pounds p e r s q u a r e f o o t a g o i n s t o r i - f i c e s o b t a i n e d f r o m t h e B a t i o n a l B u ~ e a u of S t a n d a r d s ; t h e o r i f i c e coeffici.ex-5 d e t e r x i n e d f o r a l l o r i f i c e s a i t h f l o m i n c i t h e s d i r e c t i o a v a s 0 . 5 9 .

'xaru, F a l a n c e System The b a l a n c e s y s t e m i s shol-vr. i n f i g u r e 2. The f l o a t - i n g m o u ~ l t i n g p l a t e and t h e a t t a c h e d box forrred o n e s i d e of a p a r a l l e l o g r a m mhose o ~ p o s i t e s i C e a a s a r i g i d s t e e l .

p i p e a t t a c h e d t o a c o r ~ c l - e t e p i l l a r e x t e n d i n g up f roin t h e f l o o r of t h e b ~ i l d j . i l c . T h i s pi-pe a c t e d a x a d u c t , b e i n g coiinect&d. t o t h e f l o a t i;lg chamber t k r o u s h t t ~ o f l e x i b l e j o i n t s , a s shown i n t h e f i g u r e , B a l l S e a r i n g s were u s e d 9-,.t a l l f o u r j o i n t s o f t i l e p a r a l l e l o g r a m . The f l o a t i n g ci1:tmber a n d t h e a t t a c h e d s t r u c t u r e w e r e c o u n t e s w e i ~ h t c d , - a n $ t h e d r a g s c a l e mas a t tac?le(l. by v i r e a s shown. Sue- f i c i c n t c o u n t e r w e i g h t mas a p p l i e d t o a s s u r e t c n s i o n i n t h e b a l 2 n c e n i r c a t a l l t i m e s .

Thc s c a l e mas of tlzc beam t y p c , a u t o m a t i c n l l y o p e r - z t e d by a motor a n d e l e c t r i c c o n t a c t s a t t&-e e n d o f t h e b e ~ m . O i l d a s h p o t s v e r e u s e d f o r damping t h e l a t e r a l and- t ? l e v e r t 5-cal u s c i l l a t i o n s of t h e f l o a t i n g m o u n t i n g p l a t e ,

azicl c l e a r a n c e between t k e lat to a n d t h e s u r r o u n d i n g m e t a l

f r a m e n a s a s s u r e d by a s y s t e m of i n d i c a t i n g l i g h t s .

The b a l l - b e a r i n g j o i n t e d ~ a r n l l e l o g r a m and f l e x i b l y c o u p l e d 2 u c t w e r e a r r a a c e d i n s u c h a manner a s t o r e d u c e t o n m i n i n u z t h e d r a g c o r r e c t i o n r e s n l t i n g fro?. p r e s s u r e a:ld f l o n i n t h e s y s t e ~ . The $ l a t e o p e n i n g mas s t o p p e d up a n d d r a g t e s t s w e r e r u n t h r o - o ~ l i t B c c o m p l e t e r a n g o of pos- i t i v e a a d n e g a t i v e p r e s s u r e s ; t h e c o r r e c t i o n d u e t o p r e s - s u r e n a s f o u n d t o h e n e g l i g i b l e . With t u n n e l v e l o c i t y z e r o a n d t h e p l a i n c i r c u l a r :lolcr, c o n k r a l l y l o c a t e d i n t h e f l o a t i n g p l a t e , t 3 e c o r r e c t i o n s f o r f l o w i n b o t h d i r e c - t i o l s w e r e d o t e r n i n c d . The c o r r c c t i o n f o r f l o w i n t h c i n - l e t d i r e c t i o n arnoxnts t o a, m a s i a i ~ - m of a b o u t 5 p e r c e n t : of t h e d r a g . The c o r r e c t i o ~ f o r f l o m ir, t h e o i r t l e t d i r e c t i o n i s of o p p o s i t e s i g n ann a b o u t o l e - h a l f a s g r e a t a s t h a t f o r t h e i n l e t d i r e c t i o n a t a ~ l g g i v e n r a t e of flom.

MODELS A p i c t o r i a l i n d e x of t h e s e n e r a 1 a r r a n g e ~ e n t s i n v e s t i - g a t e d i s give:^ by t a b l e s I and T I ; t h e numbers u n d e r t h e s k e t c h e s r e f e r t o t h o f i g u r e s t h a t g i v e t h e c o m p l e t e dc- t a i l s . P h o t o s r a p h s o f models a r c shown i n f i g u r e s l a n d 5 anrl Crawings a r e i n c l u d e d v i t h t h e c h a r a c t e r i s t 5.c c u r v e s o f f i g u r e s 11 59 and 62 t o 66. Tlie f l a t p l a t e a n d a l l t h e h i n g e d f l a p s t e s t e d o n i t a n d on t h e N . A . C.A. 0018 w i ~ g xzodcl w e r e of 1 / 1 6 - i n c h s t e c l p l a t e . The f l a p s u r - f a c e s mere p l a n e ail?. t h e eclgcs s h a r p . Tile c i r c u l a r p i p e u s e d f o r d u c t s and models i n f l u t - p l : ; t e t e s t s vas 3 - i n c h s e n m l e s s s t e e l tubi.n,y of a'iout C , 0 3 0 - i n c h w a l l t h i c k n e s s .

The e x t e r n a l s c o o p - t y p e i ~ l e t s and o u t l e t s w e r e formed f r o m s h e e t c o p p e r a b o u t 1 / 3 2 i n c h t h i c k ; a n d t h e r e c c s s - ty-oc i n l e t s a n d o u t l e t s mere made of g a l v a n i z e d i r a n , a l s o 1 / 3 2 i n c h t h i c k .

- - I t may be n o t i c e d t h a t s l i g h t d i f f e r e n c e s e x i s t b e t n e e n t h e a r e a s t h a t may b e t h e t a b u l a t e d a r e a s of o p e n i n g s a n d The l i n e a r computed f r o m t h e b i r j e n s i o n s o-r? t h e i r a w i n g s .

- a n d t h e a n g u l a r d i m e v s i o n s g i v e n a r e a p g r o x i n ~ t e l y c o r r e c t , but, t h e t a b u l a t e 8 a r d a s n r e t h e r e s u l t of c a r e f u l measure- m e n t s o f t h o openll-.;s a s t e s t e d . T3e t a b u l a t e r ! a r e a s w e r e u s e d i n t % e r e d v . c t i o n o f t h e d a t a t o c o e f f i c i e n t form.

A l l t h e g u i d e v a n e s were of t h i n s h e e t b r a s s , s h a p e d a s recommended i n r e f e r e n c e 3. The s e t of v a n e s u s e d i n t h e r e c e s s - t y p e o p e n i n g s n a s a d j u s t e d so a s t o d i v i d e t 5 e be~xd i n t o f o u r n e a r l y e q u a l p a r t s w i t h e i t h e r t h e 10' o r t h c 15' r e c e s s . The t h r e e v a n o s , a s a u n i t , m e r e s h i f t e d when no ce s sarj-.

Tne 36- 'by 35-5-nch I7.A,C.A. OOZE: wing ~ o d e l shown i n f i g u r e 5 was' wood, p a r t l y c o v e r e d by 1 / 8 - i n c h - t h i c k p r e s s e d - wood b o a r d . T R O r i b s d i v i d e d t h e i n t e r i o r i n t o t h r e e n e a r - l y e q u a l corfl>artments, t h e c e n t r a l onc h a v i n g a c l e a r w i d t h o f 1 2 i n c h e s .

7 n c n t h e wing was mounted i:l t h e t u ~ n e l , t h e s t e e l p l a t e a t i t s end w a s f a s t e n e d t o t h e f l o a t i n g chamber a s tlr.ovgh t h e c o m p l e t e n i n g w e r e a n o p e n i n g b e i n g t e s t e d on t h e f i a t niounting > l a t e . Tho wing e x t e n d e d 1 6 i n c h e s a b o v e a n d 20 i n c h e s below t h e h o r i z o n t a l c e n t e r l i n e o f t h e m o u n t i x g p l a t e . Bccau.se t h e t r a i l i - n g edge would h a v e b e e n o n l y 3 f n c h e s a b o v e t h e l o n e r edge o f t h e p l a n e shomn i n f i g u r e 1, t h e p l a n e wa,s e x t e n d * > d m o t h e r 2 f e e t i n t o t h e e x i t c o r e ( s e e f i g . 2 ) b e f o r e t h o wing v a s i n s t a l l e d , O p e n i n g s i n t h e two s i d - e s of t h ~ wind n e r e , i n s o f a r ads ~ o s s i b l e , rnh2.e e x a c t l y a l i k e a n d t h e a n g l e of a t t a c k w a s m a i n t a i n e d a t z e r o t h r o u g L o u t t h e t e s t s .

RESULT S Symbols and C o e f f i c i e n t s Tbc t.:ymbols a n d c o e f f i c i e n t s u s e d h e r e i n a r e d e f i n e d a s f o l l o w s : A , month a r e a of o p e n i n g , u n l e s s o t h e r w i s e d e f i n e d .

Ad, g-uct k r c a at l o c a t i o n of p r e s s u r e t a p .

D , d r a g .

- - d i- p , s t a t i c p r o s s u r _ e _ . r e l a t i - y - g - - t t h a h f f r e e s t r e a m .

~~45535=-=-55; -4 q , d-ynamic p r c s s u r o of f r e e s t r e a n , u n l e s s q u a l i f i e d .

q " , d y n n n i c p ~ c s s u r e a t edge o f boundary l a y e r .

p , mass d c n s i t g of a i r . C, \ Q , volurne of f l o m p e r u n i t tirne.

H , t o t a l . h e a d .

- -- - v = J ~ ~ / ~ , v e l o c i t y o f f r e c s t r o a n .

V 1 , v e l o c i t y a t a a y p o i n t .

V " , v c l o c i t y :.tt a n y p o i n t a t c d g e o f boundary l a y e r .

z - 4

Q / A V , c o e f f i c i e n t of f l o w .

F / q , c o e f f i c i e n t o f s t a t i c p r e s s u r e .

~ / q - p/q -I- ( B / A ~ ) ' ( Q / A V ) ' , c o e f f i c i e n t of t o t a l d.

p r e s s x r e .

D / ~ A , c o e f f i c i e n t of d r a g .

C p L , c o e f f i c i e n t of power l o s s .

~ , / 7 , t h e o r e t i c a l v e l o c i t y r a t i o a t i n l e t .

I t h e o r e t i c a l v o i o c i t y r a t i o a t o u t l e t .

v ~ / v , Q//.

C = , o r i f i c e c o e f f i c i e n t .

/31- Y c-.=3/P S u b s c r i p t s : i , . i n l e t .

o , o u t l e t , .A s t a n d a r d form of p r e s e n t a t i o n of t e s t r e s u l t s h a s 4 5een a d o p t e d , a l l t h e v a r i a b l e s b e i n g e x p r e s s e d as dimen- s i o n l e s s c o e f f i c i e n t s . The f l o w c o e f f i c i e n t Q/AV ' i s t h e r a t i o of t 3 e a v e r a g e v e l o z i t y t h r o u g h t h e a r e a A t o t h e v e l o c i t y of t h e f r e e s t r e a m , where A i s u s u a l l y t a k e n a s t h e micirnurn c r o s s - s e c t i o n a l a r e a of t h c opening.

The d r a g c o e f f i c i e n t D / ~ A 5s alwaz-s Saned 011 t h e same a r e a a s t h e f l o w c o e f f i c i e n t , a n d D i s t h e t o t a l d r a g mixus t h e t a r e d r a g of tkie p l a i n f l a t p l a t e , o r of t h e p l a t c and t h c ming, The s t a t i c - p r e s s u r e c o o f f i c i e n t p / q - i s t h e r a t i o of l o c a l s t a t i c p r e s s u r e t o f r e e - s t r e a m dy- namic p r o s s u r e . L o c a t i o n s o f t h e r e f e r e i i c e - p r e s s u r e t a p s c ' c f o r d u c t c d o p e n i n g s a r e g i v e n on t h e d r a w i n g s , When no - .? d u c t was u s e d , t h e s t a t i c p r e s s u r e was d e t e r m i n e d a t t h e c e n t e r o f t h e t o p f a c e of t h e f l o a t i n g chamber.

The p o w e r - l o s s c o e f f i c i c n t CFL i s a c r i t e r i o n of I4 m e r i t , which may be e x T r e s s e d - a s fo2.lows: where D7J' i s tlie d r a g powcr; BQ, the p r e s s u r e pomer; a n d qQ, " U h e k i n e t i c rower of t l c ind.uced f l o w . F o r i n -

l e t s , ( H Q + qQ) r e y ? e s e n t s a v a i l a b l e power w h e r e a s , f o r

o u t l e t s , i t r e p r e s c n t s expended power; h e n c e t h e d i f f e r - e n c e i n s i g n s i n t h e r i g h t - h a n d members of e q u a t i o n s ( 1 ) a n d ( 2 ) - These c a e f f i c i e n t s , which a r e inore f u l l y d e s c r i b e d i n r e f e r e n c e 4 , may a l s o be e x p r e s s e d a s f u n c t i o n s of t h e d r a g , t h e f l o w , and t h e t o t a l - p r e s s u r e c o e f f i c i e n t s , a s f o l l o w s : E x t e r n a l C o n d i t i o n s The e x t e r n a l c o n d i t i o i l s a t t h e l o c a t i o n s o f t h e open- i n g s , w i t h t h e o p e n i n g s s e a l e d o r r e n o v e d , a r e g i v e n i n t h e f o l l o n i n g t a b l e .

L o c a t i o n on Boundary wing l a y e r 0.000c 0 n e g l i g i b l e I .800c -.08 f i g u r e 8 f l a t p l a t e V e l o c i t y d i s t r i b u t i o n s i n t h e boundary l a y e r of t h e f l a t p l a t e and a t t h e wing were d e t e r m i n e d by means of a s u r v e y comb ( f i g . 6 ) and a m u l t i p l e - t u b e macomet e r . These r e s u l t s w c r e c o r r e c t e d f o r t o t a l - p r e s s u r e g r a d i e n t ( s e e r e f e r e n c e 5) and a r e p l o t t e d i n figu;:es 7 a r d 8. The c u r v e s of f i g u r e 8 e x t e n d a b o v e u n i t y b e c a u s e t h e r a t i o of p o i n t t o f r e e - s t r d a m v e l o c i t y , r a t h e r t h a n t h e r a t i o of p o i n t t o p o t e n t i a l - f l o w v e l o c i t y , was p l o t t e d . T h e s e c u r v e s s h o w t h a t t h e boundzry l a y e r was of a b o u t t h e same t h i c k n e s s a t corres-poading p o i n t s on t h e t w o s i d e s o f t h e wing a n d t h a t i t was c o n s i d e r a b l y t h i c k e r a t t h e c e n t e r of t h e syan t h a n 10 i n c h e s i n b o a r d o r o u t b o a r d o f t h a t 10- c s t ion. Tl;e t i i i c k e n i r g a t t;ie c e n t e r was c a u s e d by t h e i n s 2 a l l a t i o n o f f l a p s 9 t 0 . 1 7 5 ~ ~ even tliough t:ie f l a p s mere c l o s e d snfi s e a l e d d u r i n g t l i e b o ~ n d a r 3 - - l a g e r deterini- n a t i o n s . Bo a c d i t i o n a l s u r v e y s v e r o n a d e a f t e r t h e ad- j u s t a b l e f l a p s were r e p l a c e d by preformed p l a t e s , but cow- p ? r i s o n of d r a g t e s t s s:ioned tl-lnt t h e b o u r d a r y - l a y e r t'_lick- c x i ~ i g shown i n f i g u r e 8 c o r r e s p o n d e d t o more t h n 7 p e r - c e ~ t o f t k e ring d r a g , even t h o a g h t 9 e span of t h e f l a p s 8 w a s l e s s t h a n 30 p e r c e n t t h a t o f t h e \ i i ~ g .

Duct P r e s s u r e G r a d i e n t s ~ ~ ~ ~ t - ~ 4 ~ 1 _ g t t g - t _ ~ s - ~ s _ s . n P r e s s u r e g r a d i e n t s mere measnred i n t h e c i r c u l a r axid r e c t a n g u l a r d u c t s 337 f l u s 1 p r e s s u r e t a p s i n t h e d u c t m a l l s . I n l e t g r a d i e n t s f o r t h e f l u s h , c i r c u l a r - o p e n i n g , 90' d u c t (model XP30-90, f i g . 23) a t f o u r r a t c s of f l o n e r o g i v e n i n f i g u r e 9 , t o g e t h e r w i t h - - a v e r a g e g r a d i e n t s f o x . t h e same d u c t w i t h elbow (rnod.01 2 P Z 3 6 , f i g . 27.) a n d w i t h c o n v e n t i o n a l scoops (models 5P3- P B ar;d 5P3-PC, f i g . 2 8 ) . Avcrage g r a d l o ~ l t s a r e g i v e n f o r -- t h e s c o o p s and t 3 e elbow b e c a u s e t h e v a r i a t i o n w i t h f l o w c o e f f i c i c n t o v e r a wide r a n g e mas v e r g s m a l l and shoved no d e f i n i t e t r e n d .

The r i s i n g p r e s s u r e g r a d i e n t s s h o a n i n f i g u r e 9 a r c a veil-knonn p r o p e r t y of c l b o ~ s i n duct,s and of s h a r p - e d g e e a t r a n c e s . ( S c e r e f e r e n c e 3.) Thoy a r e t h e r e s u l t of break-a;my from t h e i c s i d e s u r f a c e behinC t?ie bend, o r en- t r a n c e , a11d s u b s e q u e n t r e t u r n of t h e f l o w t o t:ie s u r f a c e f a r t h e r downstream. A f t e r t h e v e l o c i t y h a s r e t u r n e d t o a f a i r l y u n i f o r m d i s t r i b u t f . c n , t h e g r a d i e n t cLangos s i g n and s t a r t s t o f o l l o w t h e r e c u l a r p i p e - l o s s c u r v e . The d u c t l e n g t h u s e d mas t o o s h o r t t o a l l o w r e t u r n of t h e g r a d i e n t t o t h a t f o r p u r e p i p e l o s s , t h e t a p f a r t h e s t downstream b e i n g v e r y n e a r t L e rnaxinu.n s t a t i c - p r e s s u r e p o i n t f o r t h e g r e a t e r , p a r t of t h e t e s t s w i t h t h e c i r c u l a r d u c t n r ~ d b e i n g even f a r t h e r u p s t r e a m w i t h tlie r e c t a n g u l a r d ~ x c t . I t i s ob- v i o u s t h a t t h e bend a f f e c t s t h e v e l o c i t y d i s t r i b u t i o n f o r some d i s t a n c e a l o n g t h e d u c t , and t L i s i n t e r f e r e a c e s h o u l d b e c o n s i d e r e d i n t h e d e s i g n of a s ~ s t o r n . I t m i l l be of l i t t l e u s e t o expand a d u c t t h a t i s a l r e a d y f l o w i n g o n l y h a l f f u l l ; moreover, n %en3 o r o t h e r change of c r o s s s e c - t i o n v e r y n e a r t h e opening c a n n o t he assumed t o have t h e same c h a r a c t e r i s t i c s a s i t mould 'nave behind a l o n g d u c t , The f l o w c o e f f i c i e n t Q/AY mould be e x p e c t e d t o h a v e l i t t l e e f f e c t upon t h c F r e s s u r e g r a d i e n t behing- a scoop o r elbow b e c a u s e i t d o e s n o t a f f e c t t h e r a t i o of a,verage v e l o c i t i e s o n t h e two s i d e s of t h e bend. T h i s ex- p c c t a t i o r i w a s s a t i s f i e d by t h e t e s t s of models 22336, 5?3-PE, a n 8 523-PC, f o r ni:ic% a v e r a g e c u r v e s a r e g i v e n i n f i g u r e 9. On t h e o t h e r hand, t h e l a r g e e f f e c t of flow c o e f f i c i e n t upon t h e g r a d i e n t of model 3P30-90 i s seen t o be t k e r e s u l t - o f a change i n t h e r a t i o of v e l o c f . t i e s on t h e two s i d e s o f t h e bend, t 3 e bend b e i n g t h e r e g i o n of t h e o p e n i n g even t h o u g h t h e duct i t s e l f i s s t r a i g h t . The v a r i a t i o n may a l s o 3 e t h o u g h t of a s t h e r e s u l t c f a change i n t h e n,ngle of bend, The o u - t l e t - d u c t p r e s s u r e m e a s u r e ~ e n t s gave t h e f o l l o w - i n g r e s u l t s : The p r e s s u r e drop from %ox i n t o b e l l m o u t h f o r c i r c u l a r a n d r e c t a n g u l a r d u c t s , r e s p e c t i v e l y , mas 1 , 1 3 q and 1.17q i n t h e d u c t , c o r r e s p o n d i n g e n t r a n c e l o s s e s b e i a g 0.13q and O . l Y q . ?he g r a d i e n t s i n t h e d u c t s were n e a r l y s t r a i g h t l i n e s , tile p r e s s u r e d r o p p i n g a t 0,15q and 0.20q of t h e d u c t p e r f o o t f o r c i r c u l a r a n d r e c t a n g u l . a r s e c t i o n s , r e s p e c t i v e l y ; t h o s e s l o p e s mere 1i:erely p i p e - l o s s g r a d i c a t s and were n o t a f f e c t e d by e i . t i ~ e r t h e s h a p e of t h e o u t l e t onening o r t h e f l o w p a s t i t e x c e p t w i t h i n about one d i a m e t e r - of t h e end of t h e u n i f o r m s e c t ion.

These r e s u l t s show t h a t b o t h t!ie e n t r a n c e and t h e p i p e l o s s s s f o r t h e r e c t - l n g u l a r d u c t were h i g h e r t h a n f o r t h e c i r c u l a r d u c t . The e n t r a n c e l o s s e s rney have been a f - f e c t e d by t h e n e a r n e s s of t h e s c r e e n , f o r t h e y a r e h i g h e r t h a n e x p e c t e d from r e s u l t s of h y d r a u l i c t e s t s ( r e f e r e n c e 6 , p. 2 0 6 ) . The p i p e l o s s e s , t o o , a r e h i g h e r t h a n e x p e c t e d , but t h e low a c c u r a c y w i t h which - p i p e - l o s s d d t e r m i n a t i o a s c a n be made on s u c h s b o r t specimens would n o t l e a d one t o e x p e c t v e r y c l o s e agreement v i t l i o t h e r t e s t s . P i p e l o k s e s a r e u s u a l l y of s e c o ~ ~ d a r y i m p o r t a n c e , however, r e l a t i v e t o l o s s e s a t t h e o u t l e t opening.

IYTpg t e s t s . - I n t h e d e t e r m i n a t i o n o f t h e d u c t p r e s s u r e g r a d i e n t s shown i n f i g u r e 1 0 , u k i c h a l s o s e r v e a s ming flow- m e t e r c a l i b r a t i o n s , t h e s t a t i c - p r e s s u r e t u b e s were connect- ed t o a m u l t i p l e - t u b e manometer and t k e p r e s s u r e s were ob- s e r v e d o v e r a wide r a n g e o f flow c o n d i t i o n s . I n t h e s e t e s t s , t h e a i r was t a k e n i n t o t h e ming a t t h e f r o n t o r t h e r e a r a n d mas t h e n p a s s e d t h r o u g h t h e flowrrieter ( s e e t h e a p p e n d i x ) , t h r o u g h h o l e s i n t h e v i n g r i b s i n t o t h e chamber behind t h e mounting p l a t e , a;ild t h e n c e t h r o u g h t h e r e g u l a r system. The a i r mas m e t e r e d bg tLe o r i f i c e drurc.

The p o s i t i v e s t a t i c - p r e s s u r e g r n d i e n t s i n t h e donn- s t r e a m d i r e c t i q n a r e t h e r a s u l t o f a p a r t l a l c o n v e r s i o n of d y n a n i c t o s t a t i c pressure, t S e s t a t i c - p r e s s u r e i n c r c n s c s do;rnstrsam of t h e f i o n i n e t e r b e i n g i n f a i r zgrecment ! - i t 2 B o r d a l s f o r m u l a ( r c f e r e n c c 6 , pp. 207-210).

Ciinre.ct o r i s t i c s of O-penil~gs i n t h e F l a t P l a t e The c o n d i t i o n s u n d e r which t h e o p e n i n g s -were t e s t e d n i l 1 p r o b a b l y = e v e r be r e p r o d n c e d i n p r a c t i c e . Even i f t h e o p e n i n g s t h e m s o l v e s wcre b u i l t e x a c t l y ' l i k e t h e models t e s t e d , t h e f l o w a r o u n d t h e S o d i e s i n r.thich t h e y a r e p l a c e d woixld be sucli a s t o cr,use d i f f e r e n c e s i n t h e t5me arid t h e s p a c e v a r i a t i o c s of p r e s s u r e and v e l o c i t y , n h i c h might h a v e a l a r g e e f f e c t xipon t h e - aeroclycamic c h a r a c t e r i s t i c s of t h e o p e n i n g s . R e l a t i v e t o t h e a c c u r a c y w i t h which t h e s e e f f o c t s nay be e s t i m a t e d i n any p r a c t i c a l a p n l i c a t i o f l , t h e r e s u L l t s p r e s e n t e d may be c o n s i d e r e d e x a c t f o r t h e p a r t i c - u l a r c o a d i t i o n s p r e v a i l i n g . That i s , i n t h o u s e of t h e r e s u l t s of one of t h e s e t e s t s f o r a e s i g n p u r y o s e s , t.hc p r o b a b l b e r r o r i n t h e n i s n e g l i . g i b l e i n comparison v i t h t l i a t i n v o l v e d i n t h e e s t i m a t i o n of t h e e f f e c t s o f boundary-' , l a y e r c o n d i t i o n s and i l t e r f e r e n ' c e d i f f e r i n g from t h o s e of t h e o r i g i n 2 1 t e s t . Thils, t h e a b s o l u t e p r e c i s i o n i s n o t of g r c a t i m p o r t a n c e l a n d s m a l l e r r o r s t h a t remained c o n s t a n t d u r i n g a l l t e s t s may be n e g l e c t e d .

I t shoul-d be n o t e d t h a t t h e p o w e r - l o s s c o e f f i c i e n t i s u s u a l l y t h e d i f f e r e n c e between t v o numbers o f t h e same or- d e r of m a g n i t u d e , and conseq~l.cnn',lz~ i t s p e r c e n t a g e a c c a r a c y I s belot: t h a t of t h e o t h e r c o e f f i c i e n t s . Ti11z.s~ e r r o r s i n t h e o t h e r c o e f f i c i e n t s w i l l show -J.P g r e a t l y m a g n i f i e d i n t h e p o x e r - l o s s c o e f f i c i e n t , e s p e c i a l l y e r r o r s i n d r a g a t locr, r a t e s of flotv.. I n g e n e r a l , t h e lower t h e ? o v e r - l o s s

, . c o e f P i c i e n t , t h e lower i t s p e r c e n t a g e iLccldracy. The r e -

m a r k a b l e smoothness of rxosl; of t h e c u r v e s of DFL a n d t h e i n f r e q u e a c ~ . . of e r r a t i c p o i i ~ t s , I?i s p i t e of t h e t e n d e i ~ c y o f t h i s c o e f f i c i e n t t o magnify e r r o r s , i n d i c a t e t h a t t h e r e l - , a t i v e p r e c i s i o n of measurements mas h i g h .

A 1 1 t h e o r i g i n a l t e s t s of o p e n i n g s i n a f l a t p l 3 - t c

were made a t a tun:lel v e l o c i t y o f a p p r o x i m a t e l y 40 m i l e s

p e r h o u r , but many of t h e s e t e s t s mere r e r e a t e d a t a b o u t 80 rL1iles p e r hour t o 13-etermine t h e e f f e c t s of otrea:n v e l o c - i t y n c d t o s e r v e a s ckocks on t h e r e s u l t s at t h e l o v e r speed. The t u n n e l dynamic p r e s s u r e s mere m a i n t a i n e d a t c o n s t a n ~ t l:ei;.;5ts of a.lco'ilo1 r e ~ r e s e n t i n g 40 a ~ d 80 m i l e s i~ sta1:Ja:d a i r a t a r-anorneter tenpera.tu.re of 88' p e r I.,o:lT F., v h i c l , mas a li-i;S.le a b o v e t i l e a v e r a g e t e a p e r a t n r e f o r a l l , t e s t , s na"e. The dynamic ~ r e s s a r e s s e r e c o r r e c t e d f o r v a r i a t i o n s i l t e m p e r a t u r e of t h e manoineter a l c o h o l . Kcep- i n s t h e 5 e i , : i t s oI" a l c o h o l , r a t h e r t h a n t h e a c t u a i p r e s - s u r e s , c o n s t a n t made t e m p e r a t u r e c o r r e c t i o n s unnacessar;y f o r o r i f i c e - d T u m a n d i t u c t - p r e s s u r e n a n o m e t e r s . The a c t u a l v e l o c i . L i o s b o t h i n t h e Gunnel a n d i n t n c ind1lced-,flow S ~ S - t e n w e r e n o t deterrilined Gurfng t h e s e t e s t s b e c a u s e the; meye n o t r e q u i r e d , a l l r c s n l t s b e i n g g i v e n a s r a t i o s iildc- p e a d e n t of s - u a l l variat!.ons i n v e l o c i t y w i t h i n t h e a c c u r a c y of t h e , ~ < i e a s ? ~ r c r n e n t s ili6d.e.

B e s u l t s of t e s t s of o p e n i n g s i n tins f l a t p l a t e a r e g i v e n i n f i g u r e s 11 t o 59. Comparison of t h o r e s x l t s o f t e s t s run a t b o t h 40 a;ld 80 m i l e s p e r h0v.r shows v e r y l i t - t l e v a r i a t i o n ' o f c h a r a c t e r i s t i c s w i t h v e l o c i t y f o r most of t h e d e v i c e s t e s t e d , and. tb2 s m a l l v a r i a t i o n s t h a t a r e ap- p a r e n t cnn a s u a l l g b e a c c o - a n t e d f o r by t h e d i f f e r e n c e i n b o n n d a r p - l a y e r t i l i c l r n e s s a t t k . e t,wo v e i o c i t i e s . T e s t s of t h c 3- a n d 4 - i n c h - - d i a m e t e r p i p e s , t h e 2- a x d 3-inch-diame- t e r h o l e s , a n d t h e 14- a n d %-$-inch c h o r d f l a p s showed t h a t ov.tl.ei; c h a r a c t e r i s t i c s ?ire 1 : - t t l e a f f e c t e d by t h e s i z e of t h e d e v i - c e axla t h a t i n l e t c h a r a c t e r i s t i c s a r e l i t t l e a f - f e c t e d wken tlie o p e n i n g i s o u t s i d e t h e boundary l a y e r o f the p l a t e . Fhon t h e o p e n i n g , o r a p a r t of i t : l i e s mitl2.in t h e b o u c d a r g l a y e r o f t h e p l a t e , h o w e v e r , a n y v a r i a t i o n of o ~ e n i n g sfze t h a t r e s u l t s i n a v a r i a t i o n of t h e r a t i o of o p e r i n g k e i g h t t o boundary- i u y e r t h i c k n e s s h a s a l a r g e e f - f e c t ?lpon tile i n l e t c h a r a c t c r i s t 5 . c ~ . I l k i s ' b o u n d a r y - l a y e r e f f e c t 5-s c v f d e n t n o t o n l y f r o m t h e c o m p a r i s o n of t e s t s of s i m i l a r models b u t a l s o f r o n t e s t s of a s i n g l e f l a p ad- j u s t e d t o d i f f e r e n t a n g l e s so t k a t t h e o p e n i n g s a r e of d i f f e r c a t h e i g h t s . ( S e e f i g s . 1 4 a n d 17.)

" h e t e s t r c s ~ : . l t x show t h o beneficial c f f o c t s of p r o p - e r l y f a i r i l g t h e r e a r p o r t i i o r - of c o n v e n t i o n a l s c o o p s , p i ~ e s , 2nd clt?o:vn t 5 a t p r o 2 e c t i n t o t h e a i r s t r e a m aild of n e c k i n g d o v n t h e o p e n i n g s f o r 'cot11 t h e i n l e t and t h e o u t - l e t . TFiickcning a n d rou-ddi2g t h e l e a d i z g e d g e s of s c o o p s d i d l o t skon a i ~ y d.el"i;:it>e Irqprovcment a s compared - w i t ' _ ? a ncclcec?-down s l l i a r p - e d ~ e e n t r c ~ n c c , b u t t k c s e t e s t s d i d n o t c o v e r n s u f f i c i e n t r a n g e o f s h a p e s t o c o n s t i t u t e the b a s i s l o r a g c n c r a i c o c c l u s i o n .

The i l i t e r n a l f l a p o p e c i n g s a n d t h e r e c e s s - t y p e i i i l k t s and o u t l e t s w i t 5 d u c t s d i d z o t p r o v i d e much p r c s s u r e f o r

. *

m a i n t a i n i n g t h e f lorn but e x h i b i t cd v e r y low p o w e r - l o s s c o e f f i c i c n t s f o r b l o n c r - i n d u c e d f l o a . R e c o s s i n l e t s n i t % a no s n r f a c c s p r o j e c t f n g above t h c p l a n o , n c v c r t h s l e s s , p r o - duced built-.iip s t a t i c p r e s s u r e s as h i g h a s o n o - t h i r d o f t h e f r c c - s t r e a m d y n a ~ i c p r e s s u r e . ( S e c f i g . 34.)

F i g u r c s 2 8 and 55 s b o a t h a t a hood-covereg- d u c t a t 1 5 ' m i t h t h o s a r f a c e h a d l e s s bend l o s s t h a n one a t 90' m i t h t h e s u r f a c e , a s woul2 be ex-pectcd. T c s t s o f t k c r c c e s s - t y p e i n l e t s and o u t l e t s ( f i g s . 34-35, 5 8 , and 59) shoncd t h a t , f o r s h a r p 90' b e n d s , g u i d e v a n e s mere b e n e f i c i a l a:icl s q u a r e c o r n e r s mcrc s l i g h t l y b c t t e r t h a n rounded o n c s , t h c s c r e s u l t s b e i n g i n a g r e e m e n t w i t h t ' i u s e of r e f e r c n c c 3.

The e f f e c t s of g u i d c v a n e s a r c a l s o snows i n f l g u r e s 32 a n d 57.

Cross-Find O r i f i c e C o e f f i c i e n t s Frorn t h e p r e s s u r e c h a r a c t e r i s t i c s of f i g n r e s 11 and 3 8 , o r i f i c e c o e f f i c 5 e n t s C may b e compnted and c o n ~ p a r e d ' 1 w i t h o r i f i c e c o e f f i c i e n t s d e r i v e d frori: t e s t s j.n s t i l l a i r .

B e c a u s e such a comparison seemed t o b e of f u n d a m e n t a l v a l u e , t h e c u r v e s of f i g u r e s 60 and 61 w e r e p r o p a r e d f r o m t h e o r i g i n a l d a t a c o r r e s p o n d i n g t o f i g u r e s 11 a n d 38 and f r o n , a d d i t i o n a l t e s t s o f t h o same o p e n i n g s w i t h z e r o t u n n e l ire- l o c i t y .

Figu.re 60 shows t ~ i s c o e f f i c i e n t s p l o t t e d a g a i n s t t h e o r i f i c o p r e s s u r e . F i g u r e 6 1 s h o n s t h o same c o e f f i c i c n t s p l o t t e a a g a i n s t t h e r a t i o of o r i f i c e t o cross-mind p r e s - s u r e s . On t h i s b a s i s , t h e t u n n e l z e r o v e l o c i t y p o i n t s a r e a t i a f i u i t y , a n d the cross-mind c u r v e s mould be e x p e c t e d t o a p p r o a c h t h e cro ss-wind z e r o - v e l o c i t y o r i f i c e cacf f i- c i e n t s n s t h e p r e s s u r e r a t i o i s i n c r e a s e d .

B a r i a t i o n s of o r i f i c e d i a m e t e r and t u n n e l v e l o c i t y h a d l i t t l e e f f e c t upozi inlet c o e f f i c i e n t s but c o n s i d c r n b l e c f f e c t upon o u t l o t c o c f f i c i e s t s f c r t h e a r r a n g e m e n t s a-d c o n d i t i o n s i n v e s t i g a t e d ( f i g . 61).

C h a r a c t e r i s t i c s of Openings i n a n N . B . C . A . 0018 Ving Se5axt_e-ge-3-ss o f opei~&-qg-s.- The r e s u l t s of t e s t s o f s e p a r a t e s e t s , of o p e n i r g s i n t h e 3 . A . C.A. 0018 wing a r e g i v e n i n f i g u r e s 62 t o 6 6 . A l l t e s t s mere made a t a1 a i r - s t r e a m v e l o c i t y of a p p r o x i m a t e l y 80 m i l e s 2 e r h o u r , and t h e t e s t p r o c e d a r e was t h e s a n e a s f o r f l a t - p l a t e t e s t s , T a r e d r a g o f t h e ming wit11 a d j u s t a b l e f l a p s mas de- t e r m i n e d v i t h t h e f l a p s i n s t a l - l e d , b n t c l o s e d 2nd s e a l e d .

T a r e d r a g was t h e r e f o r e h i g h e r , a n d t h e b o u n d a ~ y l a y e r a t t h e r e a r f l a p s m a s t h i c k e r t h a n f o r a smooth w i r , g . T a r e d r a g o f t h e ming w i t h f i x e d o p e n i n g s was d e t e r m i n e d k c f o r e t h e n o s e o p e n i n g s w e r e i n s t a l l e d , a d r a g t e s t b e i n g made w i t h a l l f l a p s removed a n d r e p l a c e d by s n o o t h , p r e f o r ~ e d p l a t e s , c a r e f u l l y f a i r e d i n t o t h e ming c o n t o u r . Thc t a r e d r a g a n d t h i c k n e s s o f boundary 1.ayer m e r e , c o n s e q u e a t l j r , l e s s t h a n f o r t h e a d j u s t a b l e - f l a p t e s t s . Eec2vuse of t h e s e d i f f ere:?ces, t h e f i x e d o p e n i n g s r e l a t i v e t o t h e a d j u s t a b l e o n e s a r e a c t u a l l y b e t t e r t h a n shown i n t h e f i g u r e s .

I n t h e d e t e r m i n a t i o n o f t h e s t a t i c - p r e s s u r e d a t a of f i g u r e s 62 t o 6 6 , t h e p r c s s u r e t a p s u s e d w e r e t h e o n e s n e a r e s t t h e wing f l o w r n e t e r o n t h e same sj-de as t h e open- i n g s b e i n g t e s t e d , ( S e o f i g . 1 0 . ) A s t u d y of t h e p r e s - s7J.re g r a d i e n t s of f i g u r e 1 0 shows t h a t t h e s t a t i c p r e s - s u r e s a t t h e o u t l e t o p e n i n g s llrcre somew3at g r e a t e r t h a n t h o s e j u s t b e h i n d t h e f l o w x e t e r , a s h a s a l r e a d y bccn dis- c u s s e d , The p o w e r - l o s s c o e f f i c i e n t s w e r e c o l - ~ p u t e d i n t h e s a n e manner a s f o r t h e f l a t - p l a t e t e s t s . A s s u n i n g t h a t t h e dy-

namic p r e s s u - e i n t h e d u c t was e q u a l t o 3 o ( Q / B ~ ) ' i n -

v o l v e d l i t t l e e r r o r i n t h e r e d u c t i o n of f l a t - p l a t e - t e s t d a t a b e c a u s e t h e d u c t velocities w e r e f a i r l y u n i f o r m a t t h e s t a t i c - - p r e s s u r e t a p s , b 1 5 1 1 . t t h e same itssumption i n t h e cornputat i o n of p o ~ e r - l o s s c o e f f i c i e n t s of o u t l e t s i n t h e n i n g n a k e s t h o s o e o e f f i c i e n t s e r r o n e o u s l g low. F r o n t h e d a t a of f i g u r e 1 0 , i t a p p e a r s t h a t t h e e r r o r i n C F 5 i s a b o u t 0.2 (Q/AV)" f o r t h e 3.0347 s q u a r e f o o t o u t l e t s a n d o n e - f o u r t h a s much Tor t h e 0.0174 s q u a r e f o o t o u t l e t s .

To c o r r e c t $ o n mas made f o r t h i s e r r o r S e c a u s e i t i s con- s i s t e x t a n d t h e r e f o r e d o e s 110% a f f e c t t h e v a l u e of t h e r e -

s u l t s ; i t d o e s a c c o u n t , ho-.vever, f o r t h e n e g a t i v e C p L -

sLown i n f i g u r e 6 6 .

/- /' - 3 The wing t e s t s mere made c h i e f l y t o cileck t3e,,8ppl5-- c a b i l i t y of f l a t - p l a t e d a t a t o t h e d e s l g n o f o p e n i n g s i ~ : t y p i c a l . a e r o d y n a m i c bodj-es. The l o c a t i o ~ s c h o s e a w e r e , t ' - c r c f o r e , t h e p r a c t i c a l e x t r c n c s of s t a t i c - p r e s s u r e , Ye- b l o c i t y , a n d b o u n d a r y - l a y e r t1:icirness a v a i l a b l e o n t h e wodel u s e d .

Q The i n l e t and o u t l e t c h a r a c t e r i s t i c s o f t h e i n t e r n a l f l a p a t 2.0' w i t h t h e s u r f a c e a s t e s t e d on t h e f l a t p l a t e a n d on t3.a wing a r c [;iven i n f i g u r e s 67 a n d 68. T l e c h a r - a c t o i - 5 s t i c s of t h e wing-nose i n l e t a r e a l s o g i v o n : ~ n fi;- u r e (57.

F l a t - p l a t e d a t a would n o t be e x p e c t e d t o a p p l y t o oy;cn"lgs st t h e f r o n t s t a g n a t i o n p o i n t , and. f P g u r e s 67 2nd 5 8 $ 2 0 ~ t h a t s u c h d a t a a r e n o t a p p l i c a b l e e i t h e r t h e r e o r i n . c : , . - h l g k - v e l o c i t y r e g i o n , w h i c h , i n t h i s c a s e , i s t i ~ e 0 . 1 7 5 ~ l o c ~ t i o n . The d r a g c o e f f i c i e ~ t w i t h t n o n o s e ?:ilct i s i n good a g r e o r . e n t w i t h t h e v a l u e t h a t s o u l d be expcctot!

fro13 t e s t s of a f l u s h openin.; i l l a f l a t p l a . t e v i t h z e r o 'L.o.u:~Cnry l a y e r , tiut t h e p r e s s u .re c o e f f i c i e n t i s m1.1ch 7, i ;-. 'i -. - -.- ,.-. ?.er b e c a u s e no bend l o s s i s i ~ v o l v s d .

Agreemeat of f l a t - p l a t e s o c f f i c i o n t s w i t h t h o s e d e t e r - mini!d f o r t l i e 0 , 1 7 5 ~ l o c a t i o n i s p o o r , p r i ; . l c i p a l . l y 'bocau::~ o f t h e h i @ interference d r a g cau.sed by n d e p a r t u r e f r o n s?nooth f l o w a t t h a t l o c a t , fon.

d g r e e m e ~ i k of f l a t - p l a t e an$. v i n g data, a t t h e 0 . 8 0 0 ~ l o c a t i o n i s f a i r b e c a u s e t h e 3oundarj- l a y e r s a r e o f abolzt t h a same r e l a t i v e t 3 i c k n e s s a n d t h c e f f e c t s o f i n t z r f e r - e n c e a r e m a l l . T3.c p r e s e n c e of some i n C e r f e r e n c e d r a g , 3 0 - a e v c r , c o u l d a c c o u c t f o r t i e sniall aild laearly c o n a t a ~ i t d i f f c r e n c c be-ltvccn t h e d r a g c z r v e s f o r t h e o u t l e t condf- t i o i l ; t h e cu.rves a r e n e a r l y c o i c c i d c n t f o r t 3 e l n l e t con- d i t i o n . S t a t i c - p r c s s i ; . r e c o e f f - i c i c n t s o f b o t i i n l e t azd.

o u t l e t on t h e nil;g a r e l e s s t h a n o n t k c p l a t e o v e r t h e ful.1.

r.?nCe o f f l o n ; t h e d i f f e r c n c c n a y b e a s c r i b e d c h i e f l y t o t ?e d i f f e r c n t i n t e T n a l a r s a n g o r ~ e n t s and t o t h e small nega- t i v e s t a t i c p r e s s u r e n a t u r a l l y o c c u r r i n g a t t h e 0 . 8 0 0 ~ 1 o c a t i o : i .

C_2nb in.akLqns o f,.-i-~~et-~,:Ct_-~-g~-i-e$.. OP e - I T 1 i n c 3 om-

b i a a t i o n s o f i n l e t acd o u t l e t o p e x i n g s i i l t e s t e d and t h e r e s u l t s a r e g i v e n i n t a b l e 1 1 1 t o g e t i l e r ~ i t h ~ ' i l a ~ a c t o r i s t i c s cornputed from f i g u r e 4 62 t o 5 6 .

c A l l c o n b i n a t i o n t e s t s were made a t a n a i r - s t r e a n vo- l o c i t y O F 80 m i l e s p a r % o u r , t a r e d r a g s n e r e t h e same a s f o r t k c c o r r e s p o n d i n g t e s t s o f i ~ d i v i d u a l s e t s of openi;,:s, a n d s t a t i c 2 r c s s u r c s o e r c c c a s u r e d or? t k e two s i d e s of t>-c f 1o:~mcter a t t h e p r c s s u r c t a p s n e a r e s t t h e f lowmeter. TLc r a t e of f l o w n n s c o r p u t e 5 f ~ o n t h e measarad p r e s s u r e d r o p t a r o r g h t L e Elowmeter and f r o z t h e d a t a of f i g u r e 10.

?-re d r a g of t h e opcn-in,c;s i n combiiiq,tion i s , i n g ~ : l e - c a l , l e s s t h a n t i a t of t h e o p e n i n g s i n d i v i d u a l l y , a t e n d e n c y nn- t i c i p a t e ? inasmuch a s t 5 e d r a g o f oper-ings af t h e 0 . 8 0 0 ~ l o c a t i o ~ z i s r c d c c e d %y t h e boi~.ildarp-lay3r thic2rening t h a t r e s a l t s f r o m o y e n i n g s i l l t 3 e n o s e o r at t k e 0 . 1 7 5 ~ l o c a - t i o n . The pomcr-loss c o c f f i c i e L t s and t 3 e e f f I c i e n c i e s a r e c o . r . r c s p o n d i n ~ l p a f f e c t o d .

D I SCUSSIOX The Ducted System a s a Coifiplete U n i t I n r e f e r e n c e 4 , t h e i d e a l , o r t h e o r c t i c , z l , e f f i c i e a ? - c i e s a n d t h e power-1-oss c o s f f i c i c n t s a r c d e r i v e d f o r tbe g e n e r a l i z c r l induced.-flow s y s t em and f o r t h e i n p o r t a n t syc- c i a 1 c a s e of z e r o a n g u l a r i t y o f i z i l e t and o u t l e t f l o ~ r e l - a t i v e t o t h c f r e e s t r e a n . For t h i s c a s e n h o r e ili/V a n d V 0 / v a r c t h c h y p o t l l o t i c a l v e l o c i t y ra- t i o s a t i n l e t a n d o u . t l e t , r e s p e c t i v e l y ; t h a t i s , t h e ve- - l o c i t y r a t i o s t h a t a o u l d e x i s t a t a g r e a t d i s t a n c e from * t L e ind-2-ced-f low s a s t e n i f t h e r e n e r e F-o :nixicg o r l o s s of t o t a l 5 e a d .

Tron: e q u a t i o n ( 5 ) I t 3 a y be s e e n t h a t , f o r miniaum

c~~ o f t h e c o n p l o t e s - s t e n , V,/V = 1 and V i / v i s as

l ; o s s i b l e i n e i t h e r a p o s i t i v e o r a neg- f n r f roc1 u ~ i t y a s a t i v e ? . i r e c t i o n . i f a p r e s s u r e d r o p o c c u r s I n t h e s y s t e m , a s i s u - s u a l l g t h e c a s e , V,/V < P ~ / V and v t c e v e r s a .

T h e r e f o r e , i n o r d e r t h a t V , / V -: 1 , V ~ / V ~ i u ~ s t be g r e a t e r t h a n v.;iity i r - a p r e s s u r e - d r o p s y s t e m aiid l e s s t h a n unl.ty i n a p r e s s u r e - r i s e system. Those r e 2 a t i o n s k i p s d i v i d e i n d u c e d - f l o w s y s t e n s i n t o two d i s t i n c t t y p e s , onc i n n h i c ? ~ .

t h e flovi i s i n d u c e d by t h e c x t e r n a l F r e s s u r e d i f f e r e n c e a t t h e o p e n i n g s , a n d t h e o t h e r i n wliich f l o a i s i n d u c e d by a $u3p o r blower wit!lin t h e s y s t c n . The f i r s t t y p e m i l l be c a l l e d a n externally induced-flow s y s t e n , and t h e s e c o n d t y p c rill be c a l l e d a blower-ind.v.ced-flow sy s t e n . Tliere shoul-d be L O b o r d e r l i n e c a s e , s i n c e x t h a s been shonn t b t s h o a l d be a s f a r from u n i t y a s p o s s i b l e .

V~!V T l a i n t a i r i i i g i d e a l o u t l e t c o n d i t i o n s i n a n e x t e r n a l l ; induced-f low s g s t e m w i l l u s u - a l l y be imp0 s s i b l e b e c a u s e t h e p r e s s u r e a r o p t k r o n g h t L e systcrn sill be g r e a t e r tliari t h e naximun p r c s s a r e r i s e i n the p r o p e l l e r s l i p s t r e a m , t h e op- t i n u n l o c a t i o n f o r t h e i n l c t of s u c h a s y s t e n .

I n a . b l o r e r - i n d v . ced-f l o n s y s t e n , !roaever, i t should.

al1;~nys be ~ o s s i b l e t o o p e r a - t e c?t t h e d e s i r e d c o n d i t i o n .

F u r t h c r n o r c , s u c 3 a s y s t e n c o u l d be nado t o p r o v i d e a d c - q ~ 1 n . i ; ~ c o a l i n g o r v e n t i l a t i o n a t a l l . t i n e s , e- en tllov.gh 6::- s i g n c d f o r maximum cf f i c i e n c y a t o n e p a r t i c u l a r f l i g h t c o : ~ d l t i o n , b e c a u s e i t mould bc r e l a t i v e l y i n d e p e n d e n t of t h e v e l o c i t y o r a t t i t u d e o f t h e a i r c r a f t .

In t h e d e s i g n of a s y s t e n , t h e r e q u i r e d f l o m and t k e p r e s s u r e d r o p n u s t be d e t e r n i a o d , p a r t i c u l a r l y f o r a n cx- t e r n n l l y induced-f low s y s t e n f o r nhicis t h c a v a i l a b l e p r e s - sure d r o p i s l i ~ i t e d . Tilt f l o m r ~ q u i r c ~ ~ c n t . v i l l u s u a l l y be knona o r a s s u n e d a t t h c orztset bu-t c a n be d e t e r n i n e d expcri:ne::tally by a b l o g e r aud n e t c r i n g cqui-puent sv-cil- n e t h o s e u s e d i n t h e p r e s e n t i n v e s t i g a t i o n . Such e q a i p n e a t could-, n o r e o v e r , be u s e d t o d e t e r n i n e t h s p r e s s u r e d r o p t h r o c g h a x e x p e r i a e n t a l induced-f low s z ~ s t e n and t o d e t e r - m i r e t h c e f f e c t s o f changes i a t h e c y s t e n , tiliereby z l l o ~ i ~ ~ \ a ci2.t-aud- t ry n e t h o d o f a p p r o a c i i i n g t h c S e s t po s s i 3 l e d u c t arrallgolzzellt 3 . 2 a n a c t u a l im.s'z,.;~llat i o ~ . AP. e x p e r i n e ~ t a l a t t a c k on t h e p r o b l c n of duct d e s i g n i s scconnended b e c a z s o o f t h e i r r e g a l a r s h z p e s o f d u c t s u s e d i a a i r c r a f t and t h e fr3a.v-cncy o f b e n d s , exi3a:lsio:is, c o n t r i c t i o n s , a n d o t h e r c h a n g e s o f c r o s s s e c t i o n ; a n a n a l y t i c a l sol.ution. moul8 :lot b e f i c p e ~ i d a b l e e x c e p t f o r a few siinple arrangexle:its f o r which a d c q u a t e t e s t r e s u l t s a r c available.

The I n l e t Opening I d e a l c1larac-~~rr~stt~-ci:g.- Tram r e f e r e n ce 4 , t h g i d e l l c h a r a c t e r i s t i c s of a n i n l e t o ~ e n i n g f o r t h e s p e c i a l c a s e o f z e r o a r i g l e o f a p p r o a c k a r e a s f o l l o w s :

/ .. ( p . ! a ) 2

r 9 1 J Tllese e q u a t i o n s , ~ r h i c i i a r e p l o t t e d i,n f qgure 6 9 , c l e a r l y i l l u s t r a t e tiie e f f e c t s o f - v " ; / ~ a n d Q,BV up011 t k e s h ~ r - . L a c t c r i o t i c s o f a2 i n l e t o p e n i n g .

Q-dgt---de_gi-gp f o il. .ex% er.gl,ly i ndnc ed- f 10 'CV 1;3i-gt_~e_~~_ -

Theory i u d i c a t o s t h a t t h e Lnlot o p e n l n g of a n e x t e r n a l l y i n d u c e d - f f o r system s h o u l d be i n t h e r e g i o n of oaxinlxxn t o t a l h e a d ; t h a t i s , t h e r e g i o n i n t h e p r o p e l l e r s l i p s t r e a a c o r r e s p o x d i n g t o a b o u t t k c 0.75 r a d i u s . T e s t s i n d i c a t e , n o r e o v e r , t h a t t h e o p e n i n g s h o u l d bc a t t h e f o r w a r d s t a g - n a t i o n p o i n t on a t ; ~ p i c a l aerodynamic body. If so l o c a t e d , t h e c h a r a c t e r i s t i c s of t h e oponing nag be c o n ~ u t o d fyom t h e t h e o r y , t h e a c c u r a c y of s u c h z cornputat i o n b e i n g shown by tile corrpsrison i n f i g u r e 67 f o r t h e s p c c i a l c a s e of V ~ / V = 1 . 0 . I f d e s i r e d , a n a l l o w a n c e xay be uade f o r t h e s x a l l d i s c r e p a n c i e s shon2.

F i ~ u r e 67 shows t h a t t h e a c t u a l c h a r a , c t e r i s t i c s o f t h e n o s e i n l e t t e s t e d a r e v e r y n e a r l y i e o a l . I t x u s t be r e - meinbered, however, t h a t t h e t e s t i n s t a l l a t i o n , w i t h open- i n g s on t h e cLord l i n e of a s y n m e t r i c a l wing a t zoro l i f t , i s n o t l i k e l y t o be r e p r o d ~ ~ c e t ! f n y r n c t i c e . k t o ~ e : ~ ~ e ~ t of t h o s t a g n a t i o n p o i n t n i t h c2iangc i n l i f t c o e f f i c i e n t v i l l make i t ir;lpossiblo t o n a i n t a i n t h e o ~ e n i n g a t t h e s t a g n a - t i o n p o i n t o v e r tile f u l l f l i g h t r a n g e zzssless some prac- t i c a l n e t h o d i s d e v i s e d f o r v a r y i r g t 3 c i n l e t l o c x t i o n .

Evcx a s n n l l d i s p i a c o x e n t of t h e i n l e t r e l a f i v e t o t h e s t a g n a t i o n p o i n t vou-ld be e x n e c t c d t o i n c r e a s e t h e d r a g and d e c r e a s e t k e a ~ - a i l n b l e p r e s s u r e , but t h e n a g n i t u d e of t h o s e l o s s e s c a ~ n o t be 2 r e d i c t c d from the r e s u l t s of t h e p - e e e n t i n v e s t i g a t i o n . Anotlier l o s s t h a t w i l l g e n e r a l l y be e n c o u n t e r e d i n p r a c t i c a l i n s t a l l a t i o n s of ving-nose i ~ i - l e t s i s a bend l o s s j u s t j.zsi.de t h c opening. Su-c3 a l o s s was n o t !:)resent i n t b e t e s t i n s t a l l a t i o n b e c a u s e of t 3 e s y n - ~ e t r y of t h e nod01 a n d of t h e flom r e l a t i v c t o t k e c h o r d l i n e .

Co~q-put ed c ? t a r a c t e r i s t i c s of a well-shaped 2nd ~ r o p e r l y l o c a t e d o p e n i n g a t t h e nose of a f u s e l a g e ;?ax be raore r c - l i a b l e t h a n f o r a ning-nose :@let o r a s c o u n t of t h e s z a l l e r r e l a t i v e c o v e r e n t of t h e s t a g n a t i o n y o i n t .

Bccausc o f F r a c t i c a l c o i l s i d ~ r a t i o n ~ , i t m i l l o f t e n be found d e s i r a b l e t o l o c a t e t h e i n l e t o p e z i n g of a n e x t e r - a x l l y i n d u c e d - f l o v s y s t e n b ~ c k of the f o r n a r d p o s i t i v e - p r e s s u r e r e g i o n . 111 such i n s t a l l a t i o i ~ s i t i s seconz-ie:idcd tknt t h e i n l e t be l o c n t s d 2s n e a r t k e t r a i l i n g edge a s p o s s i B l e i ? n o r d e y t o r e d u c e i n t e r f e r e r , c e d r a g and t o t a k c a d v a n t a g e 0 5 t h e 3 a t u r a l scstic-press- re r i s e . The opcn- i n s s h o u l d bc o u t s i d e t h e boundary l a y e r , and t h e scoop s h o u l d be necked Cown a t t h e f r o n t and p r o p c r l y f a i r e i t a t t h c r e a r . I f a s i ~ o r t r a d i u s bencl i s r c a x i r o d , i t sli?ulG- be f i t t e d . n i t h g u i d e v a n e s a s p r e s c r i b e d i n r e f e r e n c e 3.

I n 1 e t sx&ea_g. - 'i? o t h

d e s i-gn f o r -b_~ooqe.~=.ii~d-u c e z l , f Lo'ci t h e o r y and t e s t r e s a l t s shorn t h a t t h e i n l e t opening of a blower-induced-fl.om s y s t e m s h o u l d be a s n e a r t h e r e a r s t a g n a t i o c p o i n t a s p r a c t i c a b l e i n o r d e r t o r e d u c e t h e i n t e r f e r e l ? c e d r a g and t o t a k e maximnn a d v a x t a g e of t h e boundary l a y e r and t h e p o s i t i v e s t a t i c p - a s s u r e . The r e a r - n a r d l i m i t i n g p o s i t i o n of t h e o p e n i n g w i l l be d e t e r m i n c d bg n e c e s s a r y d a c t s p a c e and by t h e c o n s t r c c t i o n of t h e ~ i n g o r f u s e l a g e , e s p e c i a l l y v h ~ r e movable s u r f a c e s a r e employed, s u c h a s h i g h - l i f t o r c o n t r o l d e v i c e s .

T e s t s of b o t h t h e f l a t p l a t e and t 3 e wing showed t h a t t h e e x t e r n a l f l a p h a s a h i g h e r l o s s t h a n t h e i n t e r n a l t y p e a n d t h a t t h e p r e s s u r e r e c o v e r y i s improved by t h e u s e o f a n expallding s e c t i o n i n s i d e t h e o p e n i n g , s u c h a s mas u s e d i n t h e c a s e of t h e o v e r l a p p i n g f l a p s . The opcning WBIB ( f i g . 64) was t h e b e s t of t'nose t e s t e d , a n d tile c h a r a c t e r - i s t i c s of t h i s t y p e o f opening would be e x p e c t e d t o i m - p r o v e a s t h e r a t i o of o p e n i n g gap t o b o a n d a r y - l a y e r t h i c k - n e s s i s d e c r e a s e d ; i . e . , a l o a g narrom openivg should b e b e t t e r t h a n a s h o r t midc onc of t h e sa-ile a r e a 'becanse it w i l l t a k e i n a i r o? a l o v c r a v e r a g e t o t a l head.

The d r a g of a well-shaped o p e z i c g n e a r t h e t r a i l i n g edge may be e a s i l y C O E L ~ ~ I X ~ ~ C ~ . t v i t k i s a t i s f a c t o r y a c c u r a c y from e q u a t i o n ( 6 ) i f t L e v e l o c i t y i . i s t r i b u t i o n i n t.he boundary l a g e r i s known.. The r e s u l t s of such c o m p u t a t i o n s a r e g i v e n i n t n b l e I V , Oogether w i t h t e s t r e s u l t s , and i t may be s e e n t h a t t h e computed d r a g s a r e v e r y n e a r t h e measured d r a g s e x c e p t f o r t h e e x t e r n a l f l a p s , n h i c h n a t u r a l l y ex- p e r i e n c e a n a d d i t i o n a l form d r a g . I n tile coriiputatlons, f l o w c o e f f i c i e n t s n e a r t h e p o i n t of ninimum C p L mere c h o s e n .

T a b l e IV a l s o s h o q s t 3 a t , f o r t h e o p e n i x g s t e s t e d , t h e measured s t a t i c p r e s s u r e s a r o l e s s t h a n t h e c o ~ p u t e d t o t a l h e a d s by r o u g h l y 1 . 5 t i n o s t h e dynar2ic p r e s s u r e o f t h e a i r f l o w i n g t1:rough t h e g a p , e x c e p t f o r t h e i n t e r n a l f l a p s a t r c l a t i v c l y high a n g l e s . These p r e s s u r o d r o p s more a n t i c i - p a t c d f r o m p r c v i o u a k n o n l o d ~ c of f l o w t h r o u g h a s m a l l open- i n g i n t o a l a r g e c h a n b e r . ( s e e f i g . 10.) F o r d e s i g n p u r - p o s e s , n a e r r o r ir, t h e c o q - ~ t : . , t i o n o f t71e F r c s s u r e c h a r a c - t e r i s t i c s i s n o t so s e r i o u s f u r t h e blo:7cr-iuduccd-flotv s p s t e n a s f o r t h c e x t e r r a l l y rnduce0-flow s y s t e m b e c a u s e t h e f l o n map be r e g u l n t cd by t h e blower.

Z%c O u t l e t Ol2ening I d e a l c h a r a c t o r i s t i c s - . - -- -- B r o n r e f d r e n c e 4 , t 2 c i d e a l c h x r s c t e r l s t i c s of o u t l e t o p c c i n g s a r c as f o l l o w s :

C3 = D / ~ A = - ~ ( Q / A v ) (v,/v) c o s 8 ( 9 )

i n trLich 6 i s t h e Izy.pnthetica1 a n g l e of t!ie e x h a u s t j e t r e l a t i v e t o t > a t of t 3 e f r e e s t r e a n .

I n S i ~ u r e 70 t 3 e s e c q a a t i o ~ s :Ire ~ l o t t c d a t t i w e e vnl-ucs of 6 f o r t k e s n o c i a l c a s e o f Tn o u t l e t e i t h e r oil z "at p l a t e o r 011 n bod-' a t s v c h a l o c a t i o n t h a t t h e l o - c ? l v c l o c i t y i s equal. t o t 2 e P r e 3 - s t r e c z ~ 1 v c l o c i t y ; i . e . , V,/V = Q:AV.

Outlet o p e n i n g s i n aerodynamic b o d i e s w i l l c a u s e i n - t c r f e r e n c c d r a g , the a.:~o-d.nt dopc2dir.g npon t i c s h a ~ e aild.

l o c a t i o n o f t h e o p e n i n g s . E v e n f l u s h opcni:?go o n f l a t p l a t - c s , ?.ovcvcr, w ' i l . 1 :not e x h i b i t i d e z l c h a r ; t c t c r i s t i c s bocac.so c f i n t e r a c t i o a o f t h e i s s u i z l g j e t 2.2d t l i e e x t e r - n a l s t r e a m , as s h o ~ c bg n cori1;a*rison of f i g u r e s 51 and 7 0 , a n d k,ecnuse d i s c h a r g e coefficients, p a r t i c u l a r l y f ~ r s h a r p - e d z e onciliiigs, a r c n o t ?;-nity, a s silown by f i g n r e s 60 a n d 62. I f t h e e f f e c t l v c a r e c s , r a t h e r t h n n t h c a c t u a l a r e a s h a d beoil u s e d i n t h e r e d u c % i o n of t , c s t d a t a , t h e a g r c 2 a c r . t b c t i - : e e n f i g - a r e s 38 a n d 7 0 would k a v o 3 e c n muc3 b e t t e r , a s n o u l d t h e a g r e e m e n t b c t n c e n t h e t h e o r y 2nd. t L c f l a t - ? l a t e c u r v e s o f f i g u r c 38.

D_l&t:i ~orr-gc~~~o_n-s_.- I n t h e d c v c l o p a e n t of t h e 'ck~e- o r y , i d e a l f l u i d Tas nssu.ned. a n d , i n t h c t e s t s , t h e den- s i t y v a r i a t i o a m a s n e g ; l i g i b l c ; b u t , i n n a n y a p p l i c a t i o n s , p a r t i c u l a r l y t o c c g i n e - e x h a u s t s y s t e n s , t h e d e n s i t y o f t h e i s s u i n g j e t y x i l l b e w i d e l y d i f f e r e n t f r o n t h a t o f t h e sLr- r o u n d i n g s t r e a x . I n a l l s u c h c a s e s correctSLons L Q ~ X S ~ b e a p p l i e d , d e 2 e n C i n g upon t h o c h a r a c t e r t s t i c s o f t h e ~ z r d i c - u f a , r d c v i c e b e i n g u s e d a n d i t s l o c a t i o n on t h e body. If c x t e r n n l i a t c r f e r e n c e e f f e c t s a r c n e g l i g i b l e , a s f o r ct f l u s h o ~ c n i n g a t t h e r e a r of a %053-, s a b s t i 5 u t i o n of t h c d e n s i t 7 of t.3e i s s u i n g J e t i r ^ t h e i d e a l e q u a t i o n s o r em- p i r i c a l c o e f f i c i c ~ t s v f l l g i v e idc3.1 o r a c t u r ? l c h a r a c t e r - i s t i c s , r e s p e c t i v e l y .

I f , o n t h e ot'ier h m & , thr? c h a r a c t e r i s t i c s a r c a l m o s t com-i;letely cl~'ucrxi:~ofi- 'by t h e e x t e r n a l f l o u , s s f o r e n ex-- terilnl-Load-type o u t l e t a t 1 0 : ~ f l o w c o e f f : c i & n t s , flit do>- s i t g of t h e e x t e r n a l s t r e a m mould be u s e d i n computing d r a g a n d s t a t i c pressure.

If t h e i n s t a l l a t i o n d o e s n o t f a l l i n t o e i t h e r of t h o foregoing c l n s s i f i c a t i o n s but i s sonicnhere between, i t a i l 1 be n e c e s s a r y t o e s t i m a t e t h e s e p a r a t e c o n t r i b u t i o a s o f i n t e r n a l and e x t e s n a l f l o w s t o t h e o v e r - a l l c h a r a c t e r - i s t i c s a n d t o c o r r e c t a c c o r d i n g l y .

e s i a n f 0 r

E.zq 1 e t 9zfL.e ils- llZ~.SL~e~au.c,eed_~-f Lo_~mms.xstte_ms -

Thnory i n d i c a t e s a n d t e s t s pyove t h e hif;h d r a g c o s t of m a i n t a i n i n g a t t h e o u t l e t opengang a t o t a l bead. y h i c h i s low r e l a t i v e t o t h a t of t h e f r e e s t r e a m . I t i s t h c r e f o y e recon~mended' t h a t t h e o u t l e t v e l o c i t y be rm. i n t a i n e d a.s 3ea.r t h e i d e a l a s p r a c t i c a b l e and t h a t t h e o y e n i n g b e l o c a t e d iil a l o n - v e l o c i t y r e g i o n , p r e f e r a b l g a t t k e r e a r of t h e body, i n o r d e r t o r e d u c e i n t c r f e r e i l c e d r a g . It seems bars-- 1 y n e c e s s a r y t o s t a t e t h a t t!ic j e t d . i r c c t i o n s h o n l d be a s nc.2r t h a t of t h e p o t e n t i a l flom n s p r a c t i c a b l e .

F i t h a g i v e n i n l e t c o n d i t i o n , t k e t o t a l h e a d at t h e o u t l e t o p e n i x g i s d e t e r m i n e d by t h e p r e s s u r e d r o p i n t h e s y s t e m . The i m p o r t a n c e of r e d u c i n g i n t e r n a l l o s s e s c a n n o t t h e r e f o r e be o v e r e m p h a s i z e d S e c a u s e such I.or;ses a r e accofii- p a n i e d by o x t o r n a l l o s s e s , n h l c h a p p e a r a s a n e r g y l e f t i n t h e wake. Thin e x t e s n s l l o s s , wliich 0ccu.r s o c l y i n 553s- terns h a v i n g m o t i o n r e l a t i v e t o t h e s u r r o u i i d i n g f l u i d , maizes d a c t d e s i g n so i-iaportant f o r a i r c r a f t u s i n g e x t o r - n n l l y iad.uced-f l o v sy s t eqs. P r e s e n t p r a c t i c e , p a r t i c u l a r - l y i n r e g a r d t o t h e c o o l i n g of a i r - c o o l e d e a g i n e s , i n d i - c a t e s t h a t t h e s e b a s i c p r i n c i p l e s have 2 o t h e r e t o f o r e been f u l - l y a p p r e c i a t e d .

&t_&.et d e e ~ L g i . - f o r b l o t ~ e r ~ ~ i n d u c edzf5.-g~-.-.s-~s4_.,e_r~.- T h e i d e a l o u t l e t c o n d i t i o n s f o r a b l o n o r - i n d u c e d - f l o r n s y s t ern a r c thi: s a n e a s f o r a n e x t e r n a l l y ind'tlccd-f low s y s t e m b u . t , n h e r e ~ s i t i n a l m o s t i ~ : , p o s s l b l e i n t h e e x t e r n a l l y induced- f l o w s y s t e m t o r e a l i z e t h e n , t h e o u t l e t c o n ? ' i t i o n s f o r t h e

b l c n o r - 9n.duccd-flow s y s t e m a r e f u l l y c o n t r o l l a b l e . E-

h a u s t i n g a t . ? r c ~ : z t r ea~!.. t.~..I;.a~; & c a d . .... .,. i s t h e --,------.-.......- !-Geal o p t iaum L - ?

but t h e p r a c t i c a l opf'ir?i~.rn n i l 1 depend. upon t h e c h a r a c t c r - i s t i . c s o f t h e b l o n e r and t h e d u c t s u s e d a n 3 !.must, there‘- f o r e , be d e t ermined f o r e a c h p a r t i c u l a r i n s t a l l a t i o n . f t s e e m s r e a s o n a b l e t o e x p e c t , h o v e v e r , t k a t t h e p r a c t i c a l optiEum w i l l seld.on be f a r f r o m t h e i d e a l .

Sample P r o b l e a - L - gxa-i~ple: A f l o w of 6.13 c u b i c f e e t p e r s e c o n n i s r e - q u i r e d f o r a r a d i a t o r s i t h t h e F r c s s G r e c h a r a c t e r i s t i c s of L - cnc ~ " i n g f l o n n c t e r shown i n f i g u r o 10 when f h c a i r p l a n e s n o c d i s 352.2 f e c t p c r secorzd (240 m.p.11.). The c o o l e r i s t o 3 e i n s t r l l e d i n a n f n g i n t h e s a n e panx:cr as t?tc f;oti:octcr, 2nd o p ~ i ~ i n g s V N I ( f i g , 64) a i l d TRZA ( f i g . 6.3) a r c t o be u s e d . I t i s a2ssuncd t3at t h e c h a r a c t e r i s t i c s g i v e n i:~ f i g - l r c s G 4 a n d 35 a r e a p ? i i c a b l c .

B r o c f i g u r o 1 0 , bF/qr = : 1.36 a n d A r = 0.033 s q . f t .

F ~ s n tkc: c u r v e s of fl a.gaZcs'c F / q of f i g u r c s 64 ?::d.

"DL - - / S v n 3 d t h e r e q u i r c r r e n t t h a t t h e d f f f s r a ~ i c e 5.n p , q for i n l e t a n d o c t l e t nu-st e q u a l 0 . 3 3 , a s j u s t c o c p u t e d , t h c p r e s s u r e c o e f f i c i e n t f o r e a c h o p e z i n g i s d e t e r m i n e d f o r - t h e c o i ~ d . i t k o n o f r n i n i ~ ~ i ~ . ~ n t o t a l CFL, Then f r o m t l i e cl.l.rves I P / o f > j q miid C , ; x g n i r s t Q/AT, t k c f l o w c o e f f i c i c i i t s a r e d e t e r l ? i n e 5 , f r o n wkich t h e s i z e s of t h e o p e ~ i i n g s n a y be c n l c u l n t e d . The v a l u e s c o d e t e r n i n e d a r c t a b u l a t e ? a s f 0 1lov.s: P ? / q

/ cpL ! Q / A V 1 I ( s q . f t . )

---------- 4 . --

C s--

T 3 e t a b l e g i v e s the optimam s i x e s of t h e opei1i:lgs f o r t h o c o n d i t i o n s a s s u n c d . I f a n y o t 3 e r s i z c s s F e a s e d , t h e C~~ n i l 1 be h i g h e r , c v e n t k o u g h t h e r e q n i r e d f l o m a n d p r c s s u r a c h a r a c t e r i s t i c s a r e o b t a i n e d . T3e t o t a l Cpz c a X c u l a t c d f o r t 3 e same n r r a n g o ~ e a t nnd n e a r l y t h c s a l e A ; ) / ~ , b u t f o r o p e n i n g s of t h c n r c a s t e s t c d r a t h e r t h a n t h c o p t i ~ i ~ ~ : ~ ~ , i s g i ~ ~ e l i i l l t a b l e 1x1 as 0 . 5 1 . I t i s t l r : ~ s e v l d o x t t h t , ovo;i thoingh thc p r o p e y s h a p e s n ~ d . l o c a t i o ~ ~ n o f o p c n i n g s a r e a s c d , t h e s y s t e n n i l 1 b c i n e f f i c i e n t , If t 3 c o p c n i a g s a r c not of t h e p r o p e r s i z e .

CONCLUSIOBS 1. The u s e of. 1-ind-tucllcl r e s u i t s f o r d o s i g n i , i g a n o p c : ~ i n g a t a p a r t i c u l a r l o c a t i o n on a n a i r c r a f t d e m n d s a k n o ~ l c d g e o f t h e e x t e r n a l f l o w a t t h a t l o c a t i o n and of t h e i n t e r n a l f l o w and t h e p r e s s u r e r e q u i r e n e n t s of t h e system.

2 . D r a g and p r e s s u r e c h a r a c t e r i s t i c s of o p o n i n z s i n a e r o d g n a n i c b o d i e s s a y be computed f r o m t h e r e s n l t s o f t e s t s on f l a t p l a t e s i f i n t s r f c r e n c c e f f e c t s a r e known.

3. The a e r o d y n a r i c a l l y b e s t l o c n t i o n f o r t h e i n l e t o p e n i n g o f a n cxterna:.ly induced-floitr s y s t e m i s a t t h e f r o n t s t a g n a t i o n p o i n t of t h e bod.$ and i n t h e rnaximi7.m t o - t a l - L e a d r c g i o n of t h e p r o p c l l c r s l f p o t r o a ~ .

4. The a c r o d y n a m i c a l l - y b e s t l o c a t i o n f o r t h e i n l e t o p e n i n g o f a b l o w e r - i n d u c e ? - f l o w systerc i s i n t h e r e g i o n - - of laxest t o t a l h e a d , p r o b a b l y a t t h e l a s e o f t h e boxndar:~ lazrer n e a r t h e t r a i l i n g edge of t h e b o d y .

- I 5 . T o r minim-am T o n e r l o s s of a2 o u t l e t o p e n i n g , tile

-- v e l o c i t y i x ~ d t h e d i r e c t i o n of t 3 e j e t sko1:-ld be maintained

a-p?roxirnatelgr t h e same a s t h a t of t h e ~ o t c n t i a l f l o g a t t h e l o c a t i o n o f t h e opci1ir.g.

L a n g l e y llomo r i a l Aerocazzt i c a l Z a . b o r a t o r y , X a t i o n a l A d v i v o r j ~ Comroitt eo f o r A e r o n a u t i c s , Laiigloy F i e l d . , Va.. , A-cgust, 3 1 , 1938.

APFEWDIX Duct Floninet e r Nee2 o f t e n a r i s e s f o r a s i m p l e t y p e of d u c t f l o w m e t e r , t h e c a l l b r a t i o n of which i s i n d e p e n d e n t of d i s t u r b a n c e s i n t h e s t r e a r ? . e i t 3 e r i n f r o s t of o r t e h i n d iL P r e v i o u s t e s t s soerne6 t o i i i d i c a t e t h a t s u c h a f l o w m e t e r c o u l d be b n i l t a s shovrn i n f i g u r e 71. I t c o n s i s t s of n number of c i r c u l a r l i o l e s o f u n i t l e n g t k - d i a n e t e r r a t i o wit11 s m a l l impact and s t a t ic-press- re t u b e s i : r ~ s t a i l e d . o-e-quart e r t u b e l e n g t h f r o m tlie o x t l e t s i d e , a s shown i n t 3 e f i g u r e . Such a n e t e r was b u i l t a n d t e s t e d i n tbc s e t - u p shown i n f i g - u r e 72.

T h i s s e t - u p i n c l u d c d a r e c t a n g u l a r d u c t n i t h b e l l m o u t h e n t r a n c e and s t a t i c - p r e s s u r e t a p s i n s t a l l e d f l u s h w i t h t h e i r i s i d e & u c t s u r f a c e a t t h e l o c a t i o n s shown i n t h e f i g u r e .

The f l o ~ m e t e r mas mounted i n t h e c e n t e r of t i l e d u c t , a n d o b s t r u c t i o n s were p l a c e d i n t h e ~ ? . ~ e i , m 1 . f o o t on e i t h e r s i d e of i.t. Each of t h e s e o b s t r u c t i o n s b l o c k e d o f f a p p r o x - i m a t e l y one-Lalf t h e d u c t a r e a , a s sllown i n t h e f i g u r e .

Sy MCails of t h e bl.omer a c d t h e o r i f i c e drum p r e v i o u s l y d.e- s c r i b e d , kno~;;n q u a n t i t i e s of a i r were drawn t h r o u g h t h e d u c t o v c r a f l o w r a n g e c o r r e s p o n d i n g t o a f l o v m e t e r p r e s - s u r e d r o p o f f r o m 1 t o 8 i n c h e s o f a l c o h o l . Ylommeter p r e s s u r e s a n d duct s t a t i c p r e s s u r e s were measured w i t h a m u l t i p l e - t u b e manometer n i t h e a c ; ~ of t h e o b s t r u c t i o n s sep- a r c t e l y i n p l a c e , n i t b no o b s t r u c t i o n s , a n d - ~ - i t h t h e tmo end h o l e s o f t h c f l o w m e t e r s t o p p e d up.

Very l i t t l e s c a l e e f f e c t was n o t i c e d o v e r t h e r a n g e of t e s t s f o r a n y g i v e n o b s t r u c t i o n . Flawmeter c a l i b r a t i o n mas l i t t l e a f f e c t e d by the o b s t r u - c t ioxls ? l a c e d b e h i n d t h e n e t e r , b u t t l i o s e laced a h e a d o f it had a l a r g e e f f e c t , a s may be s e e n i n f i g u r e 71. I n f a c t , t h e f l o a n e t e r p r e s s u r e s ap- p e a r e d t o g i v e a z u c h l e s s s a t i s f a c t o r y c a l i b r a t i o n t h a n t h e d u c t s t . a t i c p r e s s u r e s 02. tth ttm osides o f t h e m e t e r .

T h e s e d u c t s t a t l c p r e s s u r e s mere a u c h s t e a d i e r a t a n y g i v e n c o n a i t i o n o f t h e dxzct and t h e y d i d . n o t sliow so much v a r i a - t i o n . r ~ i t h c h a n g e o f o b s t r u c t i o n a s d i d t h e flowrneter p r c s - s u r c s . I t was t h e r e f o r e d c c i d e d t o uge d u c t s t a t i c p r e s - s u r e s f o r f l o w d e t o r m f n a t i o n i n t h e subseqi?.erit niilg-opening t c s t s a n d i t v n s a l s o t,h.ought a d v i s a b l e t o r c c a l i b r a t e t h e s y s t e m f o r each c o n d i t i o n o f t h e i n l e t o p e n i n g s . T h a t t h i s c?.ccision was : ~ i s e i s e v i d e n t from a s t u d y o f t % e d u c t g r a - d i e l a t c n y v e s o f f i g u r e iO n h i t l i show a much g r e a t e r v a r i a - t i o ~ o f c n l i b s n t i o n t F z a i s sl._own by t h e r e s - z l t s g i v e n j-n f i g u r e 7 1 .

From t h e r e s u l t s of t h e s e t e s t s , i t must b e c o n c l u d e d t!iat n c i t k l e r t h e f l o w m e t e r a r e s s l l r e t a p s 1101- t i l e d u c t s t a t i i c ~ r e s s : ~ - r e t a p s y i e l d 3 c a l i b r a t i o a i n a ~ p r e c i a b l y a f - f e c t e d by f l o w c h a n g e s ir. t h e d u c t ahenci o f t h o . f l o w m o t o r , Ir, 'dl. R o k u s j I ? . , a n 6 T r o L l e r , Th.: T e s t s on V e n t i l a t i o n G p e a i r ~ g s f o r A i ~ c r a f t . J o u r . l o r o . S c f . , v o l . 3 , n o . 6 , A p r i l 1 9 3 5 , p p . 2 0 3 - 2 0 8 .

2 . T e n z i n g e r , Carl J . , and H a r r i s , T2ioras A . : The V e r t i - c a l Wind T u n n e l of tl:e W a t i ~ n a l A d v i s o r y C o r l n i t t e e - - f o r A e r o ; i a c t i c s . T . R . No. 3137, -" a , A . C.A., 1 9 3 1 .

3 . g i r t , L o r i n g : ITe-.7 Cata f o r t h e 3 e s i g , z o f E l b o w s i n Dv-ct S y s t e m s . Gen. T l e c . R e ~ r . , v 0 1 . 3 0 , n o . 6 , J u n e 1 9 2 7 , p p . 286-2536.

4 . R o g a l l o , F r a n c i s I<.: ' 2 1 L e o ~ e t i c a l . Z a v e s t i g a t i o n o f I n d u c e d - F l o w S z s t ems. T -27. No. ( t o be p u b ] - i s h e d ) , K . d . C . A . , 1 9 3 8 .

5. Young, A. D . , a n & h a s , J . N,: The B e h a v i o r o f a P i t o t T u b e i n a T r a n s v e r s e T o t a l - - P r e s s u r e Gradient.

B, G K. 150, 1 7 7 0 , B T i t i s : a A.B.C., 1 9 3 7 .

6 . S c h o d e r , E r n e s t V., a n d Damson, P r a n c i s X.: H y d r a u l i c s .

iCcGraw-Hill Book Go., I ;E., 1 9 2 7 .

N . A . C . A . Table I . - General arrangements o f inlet openings investigated.

2 6

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I Theory, figure 69 '.

Compari son o f 7% results o f theory

-45-

+ & . ? > and experiment, r Figure 67 Figures 24,25 Figures 30,31 Figures 16,17 Figure 11 Figures 18,19 Figures 26,27 Figure 32 Figures 35,36 r P

Figures 23,28 1 . Figure 33 Figure 12 F~gure 20 '

Figure 37

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P Figure 28 Figure 63 Figure 62 Figures 13,14 Figure 21 P ,- Figure 15

Figure 29 1 Figure 6 4 Figure 64 Figure 22

-.

Table I1 .- General arrangements o f outlet openings investigated.

Theory, figure 70 Compari son o f results o f theory and experiment,

/ Figure 68 1 Figures 43,44

1 Figure 49 1 Figure 54 1 Figure 57 1

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Figure 38

Figure 55 Figure 45 Figure 50 1 Figure 58

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i' P Figure 42 Figure 48 Figure 65 Figure 66 TABLE 111. C b a r a c t e r i s t i c s o f Comb%nations o f I n l e t an?. Outl-et Oyenings i n a n Y . A . C . A . 0018 Wing Openings tested Openings tested i n coabina.tion individually (figs. 62-66) --- a cent) --

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.3 BiJI S WNI ".. " s e e f i g u r e s 6 2 , 5 3 , a n d 6 4 .

' s e e t f i G u r e s 65 and 6 6 .

C Rased o n o u t l e t a r e a .

TASLE IV. Comparison o f E x ~ e r i m e n t a l a n d T h e o r e t i c a l C h a r o c t e r i s t i c s of I a l - e t Openings

( a ) I ( 4 ) L ( 5 ) l ( 6 ) i ( 7 ) 1 ( 8 )

- -- . .- - - - -. . .- - -- - - - . - - - - - - - -- - T' ----- -

WXI-10-I- 0 , 4 0 0 WRI- 5+ 0 ,500 WRI- 5-1- 5 .500 TRIf 04- 5 ,700 WRIf 04-10 .7OQ

I

W R I - B .4OO

i

a See f i g u r e s 1 4 , 1 7 , 6 3 , aria 54.

Fi<;urc 1.- T i s d t u n n e l ~ ~ l o d i f i c s t i o n s . Xote o u t l e t opeai::: on f l o a t i n g p l a x e .

F i i u r e 2.- Iuduced-f low a;zd b a l a n c e s y s t e m s .

$i,.;u.re 3.- Bel-lnouth on d e t a c h a b l e d u c t a t -1.5' w i t h p l a t e .

F i g u r e 4.- O r i f i c e drum and blower.

-l r i ~ u r e 5 . - 3 . A . C.X. 0018 v i n g z o d c l , s3.oning a.d j u s t a b l e f l a ] ~ ope:?ir,gs a t 0 . 1 7 5 ~ a::d. 0 . 8 0 0 ~ 1 . o c a t i o n s .

F i g u r e 6.- C o m b u s e d f o r 'bo7zndarg-1a.yer s u r v e y s .

T i s u r e 7.- Boundary-lager ve7.ocity d i s t r i b u t i o q on ~ c r t i - e l l c e n t e r 1ir.e o f mounting p l a t e .

T i z u r c 8.- B o u n d a r . ~ - l a y c r v c l o c i 5 y d i s t r i b ~ a t i o n a t 0 . 8 0 0 ~ l o c a t i o z on 3 . A . C . d . n i n g , f l a p sealcd.; 80 n.p.3.

F i g u r e 9.- Duct p r e s s ; l r e grac?ie:ita. I A e t opexiilgs i n f l a t p l a t e . S e e f i g u r e s 2 3 , 2'7, ar,d 28 f o r r l i ~ ~ c n s i o n s of nod.els.

F i g u r e L O . - S c c t i o s t::ro~g77 c e n t r a l c ? ~ ~ - m b e r of X , A . C.B. 0018 ming a n d i n t e r n a l p r e s s u r e g r a d i e x t s .

F i g u r e 11.- I n l e t c L a r a c t c r i s t i c s of c i r c u l a r k o l e s i n t h i n - o x a t e , s'lioving e f f c c t s of :iolc d i a c e t c r a.:id t u a n e l ve- l o c i t y .

F i g a r c 12.- Ia1.ct c 5 a r a c t e r i s t ; i c s o f P2-irck-c!lord t r i p l e f l a p s , s l ~ o w i n g eCI'ects of f l a ~ a:;gle.

F i g u r e 13.- I n l e t c h a r a c t 2 r i s t i c s o l 1 2 - i n c l ~ - c > o r d i n t c r x a l f l a p , s?:owing e f f e c t s of' f l a p a n g l e .

F i z u r e 14.- I n l e t c h a r a c t e r i s t i c s o f % $ - i u c k - c ~ ~ o r d i n t c r : ~ n l f l a p , s h o x i n g e f f e c t s of f1a.p a n g l e .

Fig1.ur.e 15.- I n l e t c h a r a c t e r i s t i c s of 1-$-inch-ckord e x t e r i l a l t r i p l e f l a p s , s h o v i n g e f f e c t s of f l a p a n g l e and t u n l l e l v e l o c i t y . b F i g u r e 16.- I n l e t c l i a r a c t e r i s t i c s o f I@-inch-chord e x t e r n a l f l a n , showing e f f e c t s of f l a p angle a r ~ d t ~ i ~ ~ e l ~ ~ c l o c i t y .

F i g u r e 17.- I n l e t c h e r a c t e r i s t i c s of 22-inch-chord e x t e r n a l f l a p , showing e f f e c t s of f l a p a n g l e .

F i g u r e 18.- I n l e t c h a r a c t e r i s t i c s of equal-chord opposed f l a p s , showing e f f e c t s of 8 when Y i s -15~.

F i g u r e 19 .- I n l e t c h a r a c t e r i s t i c s of equal-chord opposed

f l a p s , s h o v i n g e f f e c t s o f f l a p a n g l e .

F i g u r e 20,- I n l e t c h a r a c t e r i s t i c s of u n e q u a l - c h o r d , over- l a p p i n g , opposed f l a p s , w i t h l a r g e f l a p e x t e r n a l , show- i n g e f f e c t s of f l a p a n g l e .

F i q u r e 21.- I n l e t c h a r a c t e r i s t i c s of u n e q u a l - c h o r d , over- l a p p i n g , opposed f l a p s , w i t h s m a l l f l a p e x t e r n a l , show- i n g e f f e c t s of f l a p a n g l e .

F i g u r e 22.- I n l e t c h a r a c t e r i s t i c s of e q u a l - c h o r d , o v e r l a p - p i n g , opposed f l a p s , shoming e f f e c t s of f l a p a n g l e .

F i g u r e 23.- I n l e t c h a r a c t e r i s t i c s of f l u s h o a e n i n g m i t h c i r c u l a r d u c t , showing e f f e c t s of d u c t a n g l e a n d t u n n e l v e l o c i t y .

F i g u r e 24.- I n l e t c h a r a c t e r i s t i c s of s t r a i g h t c i r c u l a r p i p e p r o j e c t i n g two & f a m e t e r s , s h o w i l g e f f e c t s of r a k e a n g l e a n d t u n n e l v e l o c i t y , F i g u r e 25,- I n l e t c h a r a c t e r i s t i c s of s t r a i g h t c i r c u l a r p i p e w i t h 45' r a k e , shoming e f f e c t s of f ~ i r i n g and l e n g t h o f p r o j e c t i o n , F i g u r e 26.- I n l e t c h a r a c t e r i s t i c s of c i r c u l a r p i p e m i t h e l - bov p r o j e c t i n g two d i a m e t e r s , showing e f f e c t s of fair- i n g a n d t u n n e l v e l o c i t y .

F i g u r e 27.- I n l e t c h a r a c t e r i s t i c s of c i r c u l a r p i p e w i t h e l - ban p r o j e c t i n g one d i a m e t e r , s h o v i n g e f f e c t s of f a i r i n g , elbom l e n g t h , a n d t u n n e l v e l o c i t y .

F i g u r e 28.- I n l e t c h a r a c t e r i s t i c s of e x t e r n a l scoop w i t h c i r c u l a r d u c t , s h o v i n g e f f e c t s of e n t r a n c e s h a p e , f a i r v i n g , a n d d u c t a n g l e .

F i g u r e 29.- I n l e t c h a r a c t e r i s t i c s of e x t e r n a l scoop w i t h c i r c u l a r d.uct, showing e f f e c t s of f a i r i n s i a f r o n t a n d r e a r .

B i g u r e 30.- I n l e t c h a r a c t e r i s t i c s of e x t e r n a l scoop w i t h o u t d u c t , s h o v i n g e f f e c t s of l e n g t h and a r e s o f mouth.

F i g u r e 31.- I a l c t c h a r a c t e r i s t i c s of e x t e r n a l scoop n i t h - o u t d u c t , showing e f f e c t s of t u n n e l v e l o c i t y , scoop s k a p c , and l o c a t i o n o v e r c i r c u l a r hole. A l s o s c r c e ; l s o v e r mcuth and t h r o a t .

F i g u r e 32 .- I n l e t c h a r a c t e r i s t i c s of e x t e r n a l scoop n i t h - o u t d u c t , s h o n i n g e f f e c t s of g u i d e vanes and scoop h e i g h t .

F i g u r e 33.- I n l e t c l i a r a c t e r i s t l c s of r e c e s s opening a n d d u c t , showing e f f e c t s o f r e c e s s a n g l e a n d e n t r a n c e s'Elnpe.

F i g u r e 34.- I n l e t c h a r a c t e r i s t i c s of r e c e s s opening and d u c t , showing e f f e c t s of c o v e r l u n g t h , g u i d e vailes, and f a i r e d e n t r a n c e .

F i g u r e 35.- I : ~ l e t c h a r a c t e r i s t i c s of r e c e s s opening sad 2 u c t w i t h p r o j e c t i n g s c o o p , showing e f f e c t s of r e c e s s a n g l e aod t n t e r n a l f a i r i n g .

F i g u r e 36.- I n l e t c h a r a c t e r i s t i c s of r e c e s s opening and d u c t v i t h p r o j e c t i n g scoop, s h o n i n g e f f e c t s of bend t r e a t m e n t .

F i g u r e 3'7.- I n l e t c h a r a c t e r i s t i c s o f e x t e r r a l scoop w i t h d u c t , s h o a i n g a f f e c t s o f I i e i g h t of openi:ig, t h r o a t ex- p s a s i o n , and g u i d e v a n e s .

F i g u r e 38.- O u t l e t c h a r a c t e r i s t i c s of c i r c u l a r h o l e s i n t h i n g l a t e , shoving e f f e c t s of 5 o l e Ciameter and t u n n e l v e l o c i t y .

-I $ i ~ ; u r c 39.- Ov-tlet c h a r a c t e r 4 s t i ~ s of l&--inch-chord i i i t e r - i i a l t r i p l e f l a p s , showing e f f e c t s o f f l a p a n g l e .

F i g u r e 40.- O u t l e t c h a r a c t e r i s t i c s of I & - i n c b c h o r d i n . t e r - n ~ t l f l a p , showing e f f e c t s of f l a p a n g l e .

F i g u r e 41 .- Ou.tlet c h a r a c t er!.st i c s of 23-inch-chord i-nt e r -

n s l f l a p , s h o n i n g e f f e c t s of f l a p a n g l e .

F i g u r e 42 .- C u t l e t c 3 a r n c t e s i s t i c s o f I&- inch-chord e x t er-

n a l t r i p l e f l a . p s , s%owin!; e f f e c t s of f l a p angl-e and tun- n e l v e l o c i t y .

F i g u r e 43.- O u t l e t c l i n r a c t e r i s t i c s of l&-inck-chord e x t e r - n a l f l a p , s h o v i n g e f f e c t s of f l z p a n g l e a ~ d t u n n e l ve- l o c i t y .

F i g u r e 44.- O u t l e t c h a r a c t e r i s t i c s of 23-inch-chord e x t e r - n a l f l a p , s h o n i n g e f f e c t s o f f l a p a n g l e .

F i g u r e 45.- O.i.;tlet c h a r a c t c r i s t i r , ~ of e r j u a l - c h o r d , opposed f l a p s , s h o a i n s e i ' f e c t s of n i e o y i s 10'.

F i g u r e 46.- O u t l e t ~ h a r a c t e r ~ s t i c s of equal-c::ord,. opposed fl-a2s, showing e f f e c t s of F nhen y i s 20 .

F i ~ u r e 47 .- O u t l e t c h a r a c t e r i c t i c s of eyu2,i-.chord, oppo sed.

flag:; a i t h cove:? p l a t e , s h o v i n g e f f e d s o f f l s p a n g l e 2nd c o v e r - ~ i a t e cl..carance.

F i g u r e 48.- 01:~tlet characteristics of u n e q u a l - c h o r d , o v e r - l a p p i n g , o ~ ~ ~ o s e ? ~ f l a p s , s ~ i t h l a r g e . f l a g e x t e r n t i l , s h o r - ir-g s f f e c t s of f l o p a n g l e and eCgc r L ~ d i u . s .

FigvLre 49 .- Out l e t ck.3.rnct erl. s t i c s of 7.~nea,ual-ckord, over-

l a p p i n g , oppo secl f l a y s , n5.t.k s m a l l $ l a p e s t o r n - i l , shon- i n g e f f e c t s of I l a p n u g l s .

Bit;i.?.re 50.- O u t l e t c h a r a c t e r i s t i . c s of cql.3.al-ckord, o v e r - l a . ~ f i i l z g , op-poser?. f li.,x>s, s5onii1,; o f f c c t s of f l a ? a.zig;lo.

F i y u r e 51.- Out l e t c h a r a c t o r i s t i c s of f 2us11 o p e n i 2 g ~ i t h c i r c n i 2 , r d u c t , skoving; e f f e c t s o f d a c t a ? g l c find t u n n e l v e l o c i t y .

Fik;ure 52.- O c t l e t c k a r n c t e r 9 s t i . c ~ of s t m i g h t c i r c u l a r p i p e ~ i t l i z e r g ra.ke + r o j e c t i n g t w o d f . a m e t e r s , showing e f f e c t s o f f a i r i z g siid. t u n n e l v e l - o c l t y .

i?j.gure 53.- O a t l e t c h a r a c t e r i s t i c s of s k r a i z h t c i r c u l a r p i 2 e .;lit?l 45' rz.ke, siio:.~i:!.g e f f e c t s of p r o j e c t i o n , f a i r i n g , and t u i l i ~ e l - v e l o c i t y .

B i s u r c 54.- 3-cLt3.et c h a r a c t e r i s t i c s of c i r c a l a r p i p e a i t i z c l b o n , showing e f f e c t s of e l b o n l e 3 g t h a x & p r o j c c t i o : ~ .

Fig%-re 55.- O n t l e t c h a r a c t c r i s t i c a of f l u s h c i r c u l - a r d u c t s v i t h and n i t h o u t hood. c o v e r s , si.?.oning e f f c c t s o f h o o d , 6-act a n g l o , and mouth o'bst rv,.c"u-on.

F i , u r c 56.- G u t l e t c h a r s c t c ? r i st i c s o f ~ x t e r i ~ z l kood v i t k o u t d u c t , showing e f f e c t s of s!ia-,e, lel?p.;th, and. a r e a oi" mouth.

F i ; : u r ~ 5'7 .- O u t l e t c h a r a c t e r i s t i c s o f e x t e r x a l liood n i C 2 o a t d ~ c t , ~ 1 ~ 0 1 i i n g e f f e c t s of g u i d e v a n e s and hood I i c i g l ~ t .

~ ' I < ; v - ~ c 58 .- r3-c.tiet c l . . n r a c t e r i s t i c s of r e c e s s o ~ ~ e ~ . ~ : i g 17!~t?.

15" r e c e s s , showing e f f c c t o . o f ~ u i d o va:Ies and c o v e r - a 1eqi;t:i;.

F i g u r e 59.- O u t l c t c h a r a c t e r i s t i c s of r e c e s s o p e n i n g , shon- i n g e f f c c t . ~ of hood l e n g t h and g r o j e c t i o n , r e c e s s a n g l e , a r d g u i d e vanes.

F i g u r e 60.- V a r i a t i o x of o r i f i c e c o e f f i c i e n t s w i t h o r i f i c e p r e s s n r e .

( a ) I n l e t ' . from c r o s s wind.

(b) O u t l e t i n t o c r o s s w i d .

F i g u r e 61.- V a r i a t i o n of o r i f i c e c o e f f i c i e n t s w i t h r a t i o of o r i f i c e t o cross-wind p r e s s u r e s .

( a ) I n l e t from c r o s s wind.

( b ) ' O~.xtl.et i l l t o c r o s s ~ i n r l .

F i g u r e 62.- I n l e t c h a r a c t e r i s t i c s of 0 . 0 5 ~ opposed f l a p s a t 0 . 1 7 5 ~ l o c a t i o n on K.4. C.A. 0018 n i n g , showing e f f e c t s of f l a p a n g l e .

Figu.re 63.- I n l e t c h a r a c t e r i s t i c s of 0 . 0 5 ~ opposed f l a p s a t 0 . 8 0 0 ~ l o c a t i o n on M . A . C.A. 0018 ming, showing e f f e c t s of f l a p a n g l e .

F i e u r e 64.- Xnlet c l ~ a r a c t e r i s t i c s of f a i r e d o p e n i n g s a t nose and 0 . 8 0 0 ~ l o c a t i o n on K . A . C . A . 0018 ming, showing e f - f c c t s o f l o c a t i o n a:id o p e n i n g s h a p e s .

F i g u r e 65.- O u t l e t c h a r a c t e r i s t i c s o f 0 . 0 5 ~ opposed f l a p s a t 0 . 1 7 5 ~ l o c a t i o n on B.A. C.A. 0018 v i n g , showing e f - f e c t s of f l n p a n g l e .

F i g u r e 66.- Oritlet c h a r a c t e r i s t i c s o f 0 . 0 5 ~ opposed f l a p s a n d f a i r e d o p e n i n g a t 0.80Qc l o c a t i o n oa 1T.A. C , A . 0018 wing, showing e f f e c t s of f l a p a1:gle and o p e n i n g s h a p e .

F i g u r e 67.- I a l e t c h a r a c t e r i s t i c s f r o m v ~ i n g t e s t s , f l a t - < p l a t e t e s t s , and t h e o r y , redrawn f o r c o n p a r i s o n .

F i g u r e 68.- O u t l e t c h a r a c t e r i s t i c s from ming t e s t s , f l a t - p l a t e t a s t s , and t h e o r y , redrawn f o r comparison.

F i g u r e 69.- T h e o r e t i c a l aerodynamic c h a r a c t e r i s t i c s of i n - l e t o p e n i n g s , s h o y i n g t h e e f f e c t of i n l o t - v e l o c i t y r a t i o ,

v , / v *

F i g u r e 70.- T l i e o r e t i c a l a o r o d g n n r ~ ~ i c c h a r a c t e r i s t i c s of o u t l e t o p e n i n g s , showing t h e e f f e c t of d u c t a n g l e . - T-

- 3

Figu-re 71.- Duct f l o ~ r ~ e t e r c a l f b r a t iolzs and. d l ~ c t p r e s s u r e g r a d i e n t s , showing e f f e c t o f o b s t r u c t i o n s .

F i g u r e 72 .- Duct f l o ~ v r z e t e r c a l i b r a t i o n s e t - u p .

Figure 4 N . A . C . A .

Dls f once f r o m plo fe, in.

Figure 7 B . A . C . A . Fige. 3,5,6 Figure Figure 6 N . A . C . A .

--

A- ----- " Figure 8 D i s f onc e from w i n g surface, in.

Disfunce f r o m plate, in.

N

0 - J 3

$ 8

I u Q $ Figure 9

--

-------

--

--- -

~ A . c . A . Figs. 10,11 AN flaps !.a''~ 10" , % ' pressed- wood board Air passage fo external flowmefer Figure 1 0 Figure 12 0 . I .2 .3 .4 .5 .6 .7 .8 .9 LO flow coefficlenf, Q/AV Figure 13 N.A. C.A.

@------ 7 P - / O + O , 0 3 4 3 .OOO -10 o - - 7 P - / 5 + 0 .0537 .OO/ - / 5 & p v---- 7P -ZO+O . 0 7 2 6 . 0 0 2 -20 -

0---7P-25+0 . 0 9 / 5 . 0 0 3 -25 -'

0 / .2 .3 .4 . 5 .6 .7 .8 .9 /.O Sfo fir-pressure coe fficien f,p/q Now coefficient, Q/AV Figure 14 6 - 2 -.8 -.4 0 .4 .8 S fofic-pressure coe ffLcLen ( p / q . .,-- Figure 15 -l.6 -1.2 -.8 - . 4 0 .4 .8 S f a tic -pressure coe ff/cienf, p / q A F i g u r e 17 N.A. C. A.

6 2 8 -.4 0 .4 .8 Sf o f ~ c - p r e s s u r e r o e fficienf, p/q Figure 18 sg.R \Ad degrees ,0343 ,000 -10 0 .a736 .002 -10 10 . / l o 6 .om -in 7n flow coeffi'c~enf, O/AV , .

Figure 19 N A. C.A.

I 2 -.8 74 0 .4 .8 /.2 Sf of ic -pressure coe fficien f, p / q Flow coe fficien f , Q/AV a Figure 20 n------yp-15 + 0 ,0478 .00/ -15 0 O--3P-20+0 ,0668 ,001-20 0 1 V----9P-/5+10 .OH66 ,002 -15 Figure 21 N.A. C.A. Fias. 22.23 7, @ ?

degrees -10 l o F/ow coefficient> O/AV Figure 22 Y 3

;;; 2

,?

.'J $ /

c

Pressure $ 0 & , \ t 4 L F : ( v, A L 7, E'o

rnp h 5q k (ir in deq

-3P3O-90 40 044/ 1000 /6f 90 n- - - - -3P3O-60 40 044/ /000 /36 60 - / 0 - -3P30-45 40 0441 1.000 / 3 45 D - - - -3P30-90 80 0441 l , O O O 163 90 -2 '/.6 .; c .%'

SL2 P)

.8 cr) 1 .4

k

QO 0 I .2 .3 .4 .5 .6 .7 .B .9 1.0 S f a f ~ c -pressure coefficient, p/q F/o w co'e fficien f, Q/AV Figure 23 N.A. C.A.

__e I Pressure fop , '--Be// moufh N o w coefficI'enf, Q/AV Figure 24 A-- - - - - -- -/f33-45 .044/ /.000 B V - - - - -/P33-45A .044/ LO00 B&F

:-[E+y -

-2.0 -/.6 -/.2 -.8 -.4 0 ' .4 Sf U.?I'C -pressure coe fficl'enl: p/y i /' 'j. _ .0322 ,533 DBH 5P3-PC - -0 ,0322 .533 DBFM 5P3-PCB----V .044/ /.OOO CH /4P45-5 ---0 - / . 2 -.8 74 0 .4 .8 Sfa fie-pressure coefficienf, p/q Now coeffcienf, U/AV . - Figure 28 Figure 29 N.A C.A -3- 0-----/3P925.0257.000 B -1 I I I I I I I I I I l j 1 1 l l l l l l l l l . l l l l l l l l l l l l l -/.6 -/.2 - 8 -4 0 .4 .8 0 / ,2 .3 4 .5 .6 .7 8 9 10 Sfoffc-pressure coeff/c/enf,p/q flow coeffic~enf, Q/AV Figure 30

-

Screen D in opening a- - ---5P3-300 40 .0490 ,001 -13P475 40 .05/4 ,001 C V - - -13P475A 40 .05/4 ,001 CBB 0---l3P4758 40 .05/4 .OO/ CAD b----5P3-1500 80 .0490.00/ H -2 -2.0 -1.6 -/.2 -.8 -.4 0 .4 0 / .2 .3 .4 .5 .6 .7 .8 .9 1 3 Sfofic-pressure coefficienl: p / q Flow coe fficien f, O/AV Figure 31 N.A. C.A.

-

a---.---- /5P ,0430 ,001 B 1 7 - - /5P -G ,0490 .00/ BG

&

k- c .?

g

P, V1 P I C f B 2 8 :4 0 .4 .8 F/ow coeffic/enf, Q/AV S f a ?LC -pressure coe fficien f, p / q Figure 32 o /6P/5-/ I042 l.000 CAE A-----/6P/5-2 ,0955 .840 B8iE , 0 - - 16PIO-I+ .I042 LO00 CAD' v - . - - /6PIO-2 .065/ .39/ BAD*.

0 / .E .3 .4 .5 .6 .7 .8 -9 1.0 Sfo flc-pressure coe fficien f p/ q NO w coe fficien f, U/AV Figure 33 I N.A.C.A.

A r e a o f openin BeN mouth-- 0 - - - - - - - - - / 6 P / 5 - 3 . / 0 4 2 /.OOO C 6 - 2 8 -.4 0 .4 S f a fic-pressure coefficienf,p/q f l o w coefficienf, Q/AV Figure 3 4 . 2 .3 .4 .5 . 6 .7 .8 .9 /.O F/ow coefficienf, Q/AV , Figure 35 N.A. C.A.

Figs. 36,37 - - - - - - , 7 A , De-

(" sq. ff. Ad foils

0 lBP/O . /042 /OOO f/oin A- - - - - - /8P/O-R . /042 l.000 B 0 / .Z .3 .4 .5 .6 .7 .8 .9 1.0 F/ow c o e f f i i e n f , O/AV Sfo fic-pressure coe fficien f , p / q Figure 36 Recess E' 0 . .P . 3 .4 .5 . .6 .7 .8 .9 1.0 Flow coe fficien f, Q/AV Figure 37 S f o tic-pressure coe f f ~ c i e n f, p/q F/o w coe fficien f, O/AV Figure 38 Figure 3 9 N . A . C.A. Figs. 40,41

I - r - - I - - -r-

n C-t - . , 2 0 2 3 4 5 6 7 8 3 1 0 Sfofic-pressure coefficient p/y Q . Row coeffic~enf, Q/AV F i gure 40 . .2 .3 .4 .5 .6 .7 .8 .9 LO N o w coef%'c/'enf, Q/AV Q .

Figure 41 N.A. C.A.

I E

-

4.44!4+

x i 7 4 e in.&. sq. if.

-4S3+/5 40 .0807 A-----4S3+3O 40 . / 7 0 / Figure 42 V----4Sl+3O 80 ,0567 ,001 30 5 ' Sfafic-pressure coe fficienf, p / q F i g u r e 43 N.A. C. A.

-

, ., Figure 44 0 . I .2 .3 .4 .5 6 .7 .8 .9 LO F/ow coefficienf, Q/AV Figure 4 5 N.A. C.A.

\ 1 I I I I l l l l l l l -.8 -.4 0 .4 .8 /.2 1.6 Sfofic-pressure coefficient p/q -.

Figure 46 A , ( i ! ! T oe- 7.0.

sg.ft. Ad tolls deq.

- 8SA- 0-10 ,0343 ,000 B 0-10

A----8SA+lO- 0 .0343 ,000 B 1 0 0 o - -8SB+20+/0 .0368 . O O O C 20 10 -.4 0 .4 .8 1.2 /.6 2.0 F/OW coefficienf, Q/AV Sf a f ic -pressure coe fficien f, p/g Figure 47 Figure 4 8 2 0 ./ .2 .3, .4 .5 .6 -7 .8 .9 LO 8 NOW c o e f i i e n f , O/AV Figure 4 9 N.A.C.A.

-----+-

t i - - - 11S+/O-20 .0652 ,001 I0 -20 '

0 - - /IS+ 10-30 ,0643 .OOl / 0 -30 - V - - - - /lS+ZO-30 .I369 ,006 20-30 S f a fic-pressure coe f f i c i e n f, p/q N o w coefficienf,Q/AV Figure 5 0 , , . . .. .

. . .: I.- ....... , ' 6 - 2 -.8 -.4 0 .4 .8 1 0 .2 .4 .6 .8 1.0 1.2 1.4 1.6 1.8 2.0 S f o f i c -pressure c o e f i c i e n f , p / q 8 F/ow coefficLenf, Q/AV - . - Figure 51 N.A. C . A .

6 -1.2 -.8 -.4 0 .4 Sf a tic-pressure coe fficien f, p/q Figure 5 2 Bell rnoufh v, A , m.p. h. sq. ff.

0 - /536-45 40 .044/ A- - - - LS36-45A 40 ,044 I 0- - 1533-45 40 ,0441 0 - - - - 1.736-45 80 ,0441 0 .2 .4 .6 .8 1.0 1.2 /.4 1.6 L 8 2.0 F/o w coe fficienf, Q/AV Figure 53 a-----25336 .044/ LO00 B&E o - - 2S3345 .

Sf af;c -pressure coe fficien f p / y F/o w coe fficien f, P/AV Figure 54

( L -2- ,?

.u

s -1

Q J _+ -3 45" -4 -5

s$k ( i J g;s 1

O------ 3S30-90 .044/ L O O 0 C

a- - - - - 5S3-15-OP.0441 1.000 C&H -'

0 - - 3S30-45 .044/ L O O 0 D 0 v - - - 1454.5-5 . .844 1 LO00 D&H 0 - - - lPS5A .0196 0.197 B,C&H ~7

8-/

.2 .4 .6 .8 1.0 1.2 /.4 /.6 /.8 2.0 F/o w coeffkienf, Q/AV Figure 55 N.A. C.A.

Hood N-. -

Sfo tic -pressure coe fficien f, p/q F/o w coefficienf, O/AV Q Figure 56 .

L+-------/3S475 .05/4 ,001 C -15.5 .0490.001 B

-- 155-G .0490.001 BAG

N.A.C.A.

sq. ff. H d J fai/s 16515-3 ,1042 LOO0 5 A-----16515-3G ./042 LO00 B&G -.4 0 .4 .8 /.2 / . 6 2.0 Sfo fic -pressure coe fficien f, p/q Sfofic-pressure coefficienf,p/q How coefficienf, O/AV Figure 59 A N.A.C.

Figs i gure ' i gure N.A.C.A.

a-- - - - WFI-/O+O .0347 .005 -10 0 P 0 - - WFI+O+IO ,0347 .005 0 10 7 O WFl-5+5 .0347 .005 - 5 5 - L Sfofl-pressure coefficienf,p/q Flow coe fficienf, P/AV Figure -62 V - - - - W R I + O + G .0/74 ,001 0 6 4 0---WRI-5+5 ,0347 ,005 - 5 5 -1.6 - 2 - 8 -.4 0 .4 .8 0 I .2 .3 .4 .5 .6 .7 .8 .9 1.0 F/ow coe fficien f , O/A V S f o fic-pressure coe fficien f , p / q Figure 63 N.A.C.A. Figs. 64,65 __P 0----WRIB .0347.005 D - v - - - - W R / A See WREA , Figure 66 Sf ofic-pressure coefficienf, p / g Flow coe fficienf, Q/AV Figure 64 Flaps , 2 7 8 ~ x .05c P-----WFE+O-I0 ,0347 .005 0 -10 b- WFf +5-5 .0347 a05 5 -5 ' . ! 4 -1.2 - 8 74 0 .4 .8 1.2 0 . . 2 .3 .4 .5 .6 .7 -8 .9 1.0 5faf;c-pressure coefficient p / q Now coefficienf, Q/AV F i g u r e 65 N.A. C.A.

Figs. 6 6 , 6 7 Allflops05c,x278c S/of007c~Z78c T Exhousf B lfxhousf D $ r , s , / s$h. Type u'eqrees o----WRE+O-6 .0/74 .OO/ B 0 -6

- A------WRE+O-I0 ,0347 .005 B 0 -10 P

0----- WRE+5-5 .0347 ,005 5 5 -5 q D - - --WREA .0347.005 - I x' C ; / 6 $ 8 1 2 v) b

B .a

$ .4 0 0 2 3 4 5 . 6 7 8 . 9 / . 0 Sfaflc-pressure coeffic~enf.p/q Flow coefhc~enf, O/AV Flgure 66 <s, z $ b Flgures u1= WNI 64 b t / - - - - - - - - WFI-/O+O 62 ? $ -- WRI-/O+0 63 Q c 7P-/O+O I4 Theory. 69 V/V=IO I - I 2 4 LJ , P 0 $ $ / 6 P

: I 2

v) .

; .8 a ?

a0 4 - 2 -.8 -.4 0 .4 8 /.2 0 2 3 .4 .5. .6 .7 .8 .9 1.0 Sfaf~c-pressure coeffic/enf,p/q NOW coeffic~enf,Q/AV Figure 67 N.A.C.A.

Figs. 70,71 % O & ?.-I , % !

.'J * - 2 a, U 3-3 & I H ' 4 g'. 0 b?

%'/ 6 $ .

. .

$ k/,2 a, U 9 .8 .

I .4 6 !

' 0 I .2 .3 .4 .5 . 6 . 7 .8 .9 LO 1.1 1.2 Pressure coefficient H / q F/ow coeffi'cienf, O/AV Figure 7 0 .

Sfo tic -orifice numbers Figure 71 N.A.C.A.

Fig. 72 Figure 7 2 .