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Source of Acquisition CASI Acquired I * >,'l l '
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h D V A I t @ E CONF I D E B T I k L REPORT ic-------
No. 212
V I T A S T B A I G E T T R k I L f B G ETlGlE kidD $II.II)LE O P L I T 8'T.hPS By %'hornas C , Muse a n d R o b e r t H, N e e l y L a n g l e y S I e m o r i a l n e r o n a u t i c a l L a b o r a t o r y Unclassified - Notice Remarked 4/17/09 December 1 9 4 1 WIND-TUNNEL INVESTIGATION O F A N NAC& LOW-DRAG TAPERED W I N G WITH STRATG.RT T B A I E I N G EDGE A N D SIMPLE; SPLIT FLAPS . .
B y Thomas C,. Muse a n d ' ~ o b e 2 . t ' H., ESealy An i n v e s t i g a t i o n was c o n d u c t e d i n t h e WACk 1 9 - f o o t p r e s s u r e wind t u n n e l of a t a p e r e d wing w i t h s t r a i g h t t r a i l i n g edge h a v i n g NACk 66 s e r i e s low-drag a i r f o i l s e c ' t i a h $ a n d e q u i p p e d w i t h f u l l - s p a n , a n d p a r t i a l - s p a n s i m p l e s p l i t f l a p s , The a i r f o i l s e c t i o n s u s s d were t h e IYICA 66,2-116 a t t h e r o o t a n d t h e 66,2--216, a t t h e t i p , The p r i m a r y p u r p o s e of t h e i n v e s t i g a t i o n was t o d e t e r m i n e t h e e f f e c t of t h e s p l i t f l a p s on t h e a e r o d y n a m i c c h a r a c - t e r i s t i c s of t h e t a p e r e d wing. Complete l i f t , d r a g , a n d pitching-moment c o e f f i c i e n t s were d e t e r m i n e d f o r t h e p l a i n w i n g a n d f o r e a c h f l a p a r r a n g e m e n t t h r o u g h a R e y n o l d s number r a n g e of 2 , 6 0 0 , 0 0 0 t o 4 , 6 0 6 , 0 0 0 .
The s e s u l t s of t - h i s i n v , e s t $ g a t i q n i n d i c a t e t h a t v a l u e s [of. maximum l i f t c o e f f i c i e n t compara"b1e t o v a l u e s o b t a i n e d . 0.n t a p e r e d wings. w-ith c o n v e n t i p n a l s e c t i o n s a n d s i m i l a r -f.l:stp ias t a l l a t . i o n s . can- b e o b t a i r ; e d f r o m wings
w i t h %he MAC& law-drag s e c t i d i s . . . The i q a r e m e n t af maxi-
m m l i f t .due t o t h e s p l i t f l a g w.as f a u n d t o v a r y sonreewba$ w i t h R e y n o l d s -nunher o v e r t h e r i n g e iny.e.s t igatied.. The : @ f a t h e .wing a l o n e i s 1>,49 at..& R ~ Y ~ Q X ~ ~ S number of
_ ) . 6 % . -
I 4 , 6 0 . 0 , 0 0 0 ; whg.reas w i t h t h e p a r t , i a l i s p a a sinnple s p l i t f l a p i t i s . - Z , 8 2 a n d w i t h t h e g u l l - s p a n a r r a n g e m . e n t , 2.8C.
. ObservaCfons o f wool . t u f t s on t h e wing i n d i c a t e t h , a t
t h e a d d i t i o n of s p l i t f l a p s d i d n o t a p p r e c i a b l y a l t e r t h e p e t t e r n of t h e q t a l l ; e v e n t h o u g h the g t a l l d i d o c c u r mare a h r u p t B y t h e n w i t h t h e wing a l o n e .
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I .
The NACB f s u n d e r t a k i n g a n e x t e n s i v e i n p e s t l g a t i o n i n t h e 1 9 ~ f o o t p r e s s u r e t u n n e l t o d e t , e r m i ~ e , t , h e e f f e c t ef v a r i o u s h i g h - l i f t d e v i c e s on t h e a e r a a y p a & i c c h a r a c t e r i s - t i c s . o f s r e p r e s e n t a t $.ve wings h a v i n g %&Ck low-drag a i r $ o i l s e c t i o n s . T h i s i n v e s t i g a t i o n i s t o i n o l a d e t e s t s of winga of d i f f e r e n t p-ian f okm e q u i p p e d w l t h . v a r i o b ~ t y p e s -of t r a i l i n g - e d g e f l a p s ; t h e e f f e c t s of a f u s e l a g e w i l l be
i'ncluded a£ ter- t h e wl;ng+ild-ne teas t s . Table' I g i v e s . a n
o u t l i n e of t h e models t o b e t e s t e d i n t h e p r o g r a m . The a e r o d y n a m i c c h a r a c t e r i s t i c s of a r e c t a n g u 1 a . r NXCk 66,2-216 wing w i t h f u l l - s p a n a n d p a r t i a l - s p a n s p l i t f l a p s of v a r i - ous c h o r d s were p r e s e n t e d i n a p r e v i o u s r e p o r t ( r e f e r e n c e l ) , t h e f i r s t of t h e s e r i e s .
The p r e s e n t p a g e r c o n s t i t u t e s t h e s e c o n d p a r t of t h e s e r i e k . , ' I n i t a r e p r e s e n t e d t h e r e s u l t s of wind-tunnel t e s t s 'of f u l l - s p a n a n d of p a r t i a l - s p a n simple. s p l i t f l a p s O n a t a p e r e d wing w f t h s t r a i g h t t r a i l i n g e d g e , c o n s t r u c t e d to. FJACA low-drag a i r f o i l s e c t i o n s .
5, .
The p l a i n w i n g , o r b a s i c m o d e l , ( f i g 1) was c o n s t r u c t - e d of l a h i n a t e d mahogany t o NkCk low-drag a i r f o i l s e c t i o n s .
These s e c t i - o n s a r e t h e 66,2-116 ( t a b l e 1 1 ) f o r t h e + ' r o o t a n d t h e 66;2-216 ( t a b l e 111) f o r t h e c o n s t r u c t # i o n t i p , %he wing p l a n f o r m c o n s Z s t s of a s q u a r e c e n t e r s e c t i o n a n d t a p e r e d outbo-ard s e c l t i o n s w i t h e l l i p t i c a l t i p s . The t r a i l - i n g edge i s a s t r a i g h t - l i n e c o n t i - n u a t i o n of t h e squar,e . c e n t e r s e c t i o n ; w h e r e a s t h e l e ' a d i n g e d g e i s swept b a c k a t a n a n g l e of 1 2 . 5 0 . The wing h a s a g e o m e t r i c t w i s t , or w a s h o u t , of 1 . 5 0 betweeri t h e o u t b o a r d ..edge sf t h e , c e n t e r s e c t i o n a n d t h e e x t r e m e wing t i p . - e : U - r - n.drx+do- .%w i ~ - t . . -0.P: , apgs .a&*-& P",
w ~ e L b . 4 f ; i a e ., -4 a p r - m d c -s-b &E I+ng *u,,-.: m e . $ er-t-s-t-3 e . '
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,[A, While no d i h e d r a l i s u s e d , a s m a l l d i h e d r a l e f f e c t is o b t a i n e d b y h a v i n g t h e wing -upper s a r f a c e b e t w e e n t h e 43-percent-chord p o i n t of t h e r o o t s e c t i o n a n d t h e 50- p e r c e n t - c h o r d p o i n t of t h e c o n s t r u c t i o n t i p l i e i n a h o r i - z o n t a l p l a n e , I n a s much'as t h e s p a n , a s p e c t r a t i o , a n d a r e a a r e 1 5 f e e t , '7.0, and 3 2 . 1 4 s q u a r e f e e t , r e s p e c t i v e l y , or i d e n t i c a l w i t h t h o s e of t h e r e c t a n g u l a r wing d e s c r i b e d in r e f e r e n c e 1 , -a f a i r c o m p a r i s o n - , o f t h e r e r a t i v e m e r i t s ' o f ' t h e two wings a a n b e 'made, A n " a e r o d y n a m i c a l l y smoathtt . s a r f a c e was o b t a i n e d b y s p r a y i n g , t h e wing w i t h a number - 6 f c o a t s of l a c q u e r a n d " t h e n r u b b i n g ' u n t i l .smooth wiBh No. 500 w a t e r c l o t h .
F l a p s .
' . .
The f l a p s . w e r e of t h e s i m p l e s p l i t t y p e w i t h a c h o r d 2 0 p e r c e n t of t h e w,ing s e c t i o n c h o r d , T h e s e f l a p s we??.@, made of l / l 6 - i n c h g a L v a n i z e d s h e e t s t e e l c u r v e d Lo appr'ox- i m a t e t h e c o n t o u r of t h e f l a p p o r t i o n of t h e w i n g l o w e r s u . r f a c e . . T h e d e s i r e d d e f l e c t i o n s w e r e o b t a i n e d by i n s e r t - i n g a p p r o p r - i a t e l y s h a p e d wooden b l o c k s b e t w e e n t h e w i n g l o w e r s u r f a c e a n d t h e f l a p . F o r t h e p a r t i a l - s p a n c o n d i - t i o n t h e f l a p s e l t e n d e d ' o v e r 53 p e r c e n t of t h e w i n g s p a n .
( s e e ' f i g ; l..) T h i s s p a n was d e t e r m i n e d a s t h e d i s t a n c e b e t w e e n t h e i n b o a r d e n d s @ f 0 . 3 7 b / 2 a i l e r o n s , s h o u l d t h e y b e u s e d . The f u l l - s p a n a r r a n g e m e n t e x t e n d e d ' a l o n g 9 0 p e r - c e n t of t h e e n t i r e ' w i n g s p a n , ;' TESTS The t e s t s w e r e c o n d u c t e d i n t h e N-cCA 1 9 - f o o t p r e s s u r e w i n d t u n n e l a t a n a b s o l u t e p r e s s u r e of 35 p o u n d s p e r s q u a r e i n c h w i t h t h e m o d e l mounted on t h e s t a n d a r d w i n g s u p p o r t s .
( S e e f i g , 2 . ) S i n c e t h e a e r o d y n a m i c c h a r a c t e r i s t i c s of t h e p l a i n w i n g a r e t h e b a s i s f o r c o m p a r i n g t h e m e r i t s of t h e v a r i o u s h i g h - l i f ' f d e v i c e s ' , + - a s e t of c o m p l - e t e L p o 1 a r r u n s w a s made f o r t h i s c o n d i f ; i o n , ' F o r t h e s e r u n s ' t h e a n g l e of a t t a c k was v a r i e d f r o m -4O t h r o u g h t h e s t a l l f o r d y n a m i c p r e z s u r e s of 2 0 , 4 0 , a n d 7 0 p o u n d s p e r s q u a r e f o o t , c o r r B s p o n d i n g t c t e s t R e y n o l d s n u m b e r s of a b o u t 2 , 6 0 0 , 0 0 0 ; . 3 , 7 0 0 , 0 0 0 ; a n d 4 , 6 0 0 , 0 0 0 ; r e s p e c t i v e l y . S i m u l t a n e o u s m e a s u r e m e n t s of l i f t a n d d r a g w e r e r e c o r d e d b y a s i x - c o m p o n e n t e l e c t r i c a l r e c o r d i n g b a l a n c e .
F o r t h e p a r t i a l - s p a n - f l a p ' a r r a n g e m e n t c o m p l e t e p o l a r r u n s w e r e made f o r f l a p d e f l e c t i o n s of 1 5 O , 3 0 ° , 45O, a n d 6 0 ° a.t d y n a m i c p r ' e s s u r e s - o f 2 0 , 4 0 , a n d 7 0 ' p o u n d s p e r s q . a a r e f o o t . C o m p l e t e - p o l a r r u n s w e r e made w i t h t h e f u l l - span-f l a p i n s t a l l a t i o n a t t h e same dyna'mic p r e s s u r e s a s f o r t h e p a r t i a l - s p a n a r r a n g e m e n t b u t o n l y f o r t h e 6 0 ° de- f l e c t i o n . .
I n o r d e i - t o p r o v i d e a b a s i s f o r *a c o m p a r i s o n of t h e a e r o d y n a m i c c h a r a c t e r i s t i c s o b t a i n e d i n t h e s e t e s t s w i t h s e c t i o n c h a r a c t e r i s t i c s o b t a i n e d i n o t h e r t w o - d i m e n s i o n a l - f l o w t e s t s , momentum s u r v e y s f o r t h e p l a i n - w i n g c o n d i t i o n w e r e mad-e i n t h e w i n g wakg a t d y n a m i c p r e s s u r e s of 4 0 a n d 7 0 p o u n d s p e r s q u a r e f o o t . M e a s u r e m e n t s w e r e made a t a p - p r o x i m a t e l y 6 - i n c h i n t e r v a l s a l o n g t h e s p a n e x c e p t n e a r t h e t i p s , w h e r e a c l o s e r s p a c i n g was u s e d , The s u r v e y s w e r e made a t a n a n g l e of a t t a c k of lo, w h i c h p r e v i - m o l y h a d b e e n f o u n d t o g i v e t h e minimum d r a g : I n o r d e r t o s t u d y t h e w i n g s t a l l i n g c h a r a c t e r i s t i c s , w o o l t u f t s w e r e f a s t e n e d w i t h c e l l u l o s e t a p e : t o t h e w i n g u p p e r s u r f a c e a t t h e 20-., 30-., 4 0 - , 60-, 70-, 80-, a n d 9 0 - p e r c e n t - c h o r d p o h t s . T h e s e t u f t s w e r e a r r a n g e d i n g a r a l l e l rows s p a c e d a p p r o x i m a t e l y 7 i n c h e s . a p a r t a l o n g t h e w i n g s p a n . S l i g h t l y c l o s e r s p a c i n g was u s e d n e a r t h e t i p s . S k e t c h e s w e r e made f r o m v i s u a l o b s e r v a t i o n s of t h e b e h a v i o r of t h e t u f t s a t v a r i o u s a n g l e s of a t t a c k t h r o u g h t h e s t a l l f o r t h e p l a i n w i n g a n d a l s o f o r t h e w i n g w i t h p a r t i a l - s p a n f l a p d e f l e c t e d , 6 0 0 . The t u f t o b s e r v a t i o n s w e r e made a t a d y n a m i c p r e s s u r e of 7 0 p o u n d s p e r s q u a r e f o o t .
. .
RESULTS A N 3 D I S C U S S I O N . .
The d a t a p r e , s e n t e d i n t h i s r e p o r t a r e g i v e n i n s t a n d - a r d n a n d i m e n s i o n a l ! coeI"f i c i e n t f o r m c o r r e c t e d f.or t h e e f - f e c t of m o d e l s u p p o r t $ a x e a n d interf,er,e.nc.e a n d f o r j e t - b o u n d a r y e f f e c t s .
The coe.ff i c i e n t s a n d s y m b o l 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 : C ; l i f t c o e f f i c i e n t ( L / ~ s ) , .
C D d r a g c o e f f i c . i e n t ( D / ~ s ) C pitching-mo,ment c o e f f i c i e n t a b o u t t h e q u a r t e r - m z g c h o r d p p i n t .of t h e p l a i n w i n g r , o o t s e c t i o n .- ( I ~ ' ~ / ~ s F ) I , CD, w i n g p r of i l e - d r a g c o e f f i c i e n t q - C o e c t i - o n p r o f . i l e - d r a g c o e f f i c i e n t ( d o / q c ) do w h e r e S_ d y n a m i c p r e s s u r e i n t h e u n d i s t u r b e d a i r s t r e a m 0 / 2 par2) S w i n g a r e a ( 3 2 , 1 4 sq f t ) - c m e a n w i n g c h o r d ~ / b ( 2 . . 1 4 f t ) c s r o o t s e c t i o n w i n g c h o r d c s e c t i o n c h o r d b w i n g s p a n ( 1 5 f t ) p mass d e n s i t y of a i r , s l u g s p e r c u b i c f o o t a n d .
f l a p d e f l e c t i o n m e a s u r e d b e t w e e n t h e l o w e r s u r - 6 f f a c e of t h e w i n g a n d t h e f l a p a a n g l e of a t t a c k of r o o t c h o r d c o r r e c t e d f o r j e t - b o u n d a r y i n t e r f e r e n - c e R t e s t R e y n o l d s number b a s e d on mean w i n g c h o r d (p V F / w ) ~1 . c o e f f i c i e n t of v i s c o s i t y . .
- ,,.
" .
P r e c i s i o n I The a c c i d e n t a l e x p e r i m e n t a l e r r o ' r s as d e t e r m i n e d f r o m r e p e a t t e s t s a r e b e l i e v e d t o b e w i t h i n t h e f o l l o w i n g l i m i t s : *o \ 0 0 0 2 . , C d o ( c 1 = 0 ) wake rt0.5' 6 f F l a p p o s i t i o n k 0 . 0 0 2 ~ The c o e f f i c i e n t s g i v e n a r e c o r r e c t e d f o r t h e e f f e c t of model s u p p o r t t a r e a n d i n t e r f e r e n c e a s d e t e r m i n e d f o r t h e p l a i n wing, No a d d i t i o n a l t a r e t e s t s w e r e made f o r t h e f l a p i n s t a l l a t i o n s , a s t h e t a r e i n c r e m e n t i s b e l i e v e d t o b e s m a l l .
P l a i n Y i n g j The a e r o d y n a m i c c h a r a c t e r i s t i c s of t h e p l a i n wing a s d e t e r m i n e d i n t h e s e t e s t s a r e g i v e n i n f i g u r e 3 a s t h e zero-f l a p - d e f b e c t i o n c o n d i t i o n , E x a m i n a t i o n of t h e l i f t c u r v e s r e v e a l s t h a t t h e s l o p e d c L / d a i s c o n s t a n t u p t o f r o m t h i s p o i n t t h e s l o p e t h e p o i n t w h e r e C L = 0 . 5 ; g r a d u a l l y d e c r e a s e s u p t o t h e s t a l l , Of s i g n i f i c a n c e i s t h e a b s e n c e of a n y i r r e g u l a r i t y a r o u n d C L = 0.3 as shown b y t h e r e c t a n g u l a r w i n g t e s t s r e p o r t e d i n r e f e r e n c e 1.
F u r t h e r c o m p a r i s o n w i t h t h e r e c t a n g u l a r w i n g shows t h a t t h e t a p e r e d w i n g h a s a g r e a t e r s l o p e of t h e l i f t c u r v e a n d a h i g h e r a n g l e of s t a l l , r e s u l t i n g i n a n i n c r e a s e o f C ~ m a x * The p i t c h i n g - m o m e n t c o e f f i c i e n t was c o m p u t e d a b o u t q u a r t e r - c h o r d p o i n t of t h e r o o t s e ' c t i o n i n t h e i n t e r - of s i m p l i c i t y s i n c e t h e a e r o d y n a m i c c e n t e r v a r i e s w i t h C L a n d R , The moment c o e f f i c i e n t c u r v e s a v e a n e g a t i v e s l o p e a n d e x h i b i t l i t t l e s c a l e e f f e c t .
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6 .
The s e c t i o n p r o f i l e - d r a g c o e f f i c i e n t s d e t e r m i n e d b y t h e momentum-loss method a r e shown i n f i g u r e 4 f o r two v a l u e s of R e y n o l d s number. The minimum w i n g p r o f i l e - d r a g c o e f f i c i e n t o b t a i n e d by t h i s m e t h o d a t a R e y n o l d s C ~ o min number o f 3 , 7 5 0 , 0 0 0 i s 0 . 0 0 3 8 , w h i c h i s i n g o o d a g r e e m e n t w i t h t h e v a l u e of 0 . 0 0 4 1 o b t a i n e d b y t h e f o r c e m e a s u r e - m e n t s .
U i n g w i t h F l a p s The a e r o d y n a m i c c h a r a c t e r i s t i c s of t h e w i n g w i t h f l a p s a r e p l o t t e d a g a i n s t a n g l e of a t t a c k i n f i g u r e 3 .
The s l o p e s of t h e l i f t c u r v e s , i n g e n e r a l , a p p e a r t o b e c o n s i s t e n t a n d u n i f o r m a l m o s t t o t h e s t a l l . Tne p e a k s of t h e c u r v e s , h o w e v e r , show w i d e v a r i a t i o n , r a n g i n g f r o m s h a r p b r e a k s t o a l m o s t f l a t - t o p c u r v e s , A t p r e s e n t n o c o m p l e t e e x p l a n a t i o n o f t h e d i f f e r e n c e s i s a v a i l a b l e , The c u r v e s d o i n d i c a t e a p r o n o u n c e d i n c r e a s e i n t h e a n g l e of s t a l l w i t h i n c r e a s e of R e y n o l d s n u m b e r , As was t r u e f o r t h e p l a i n w i n g , t h e p i t ching-moment c o e f f i c i e n t s a b o u t t h e q u a r t e r - c h o r d p o i n t of t h e r o o t whCn p l o t t e d
s e c t i o n h a v e a n e g a t i v e s l o p e - ----
d a a g a i n s t a n g l e o f a t t a c k . L i t t l e v a r i a t i o n w i t h R e y n o l d s number i s i n d i c a t e d , h o w e v e r , On t h e o t h e r h a n d , a l a r g e i n c r e a s e , n e g a t i v e l y , i s shown b y t h e p i t c h i n g - m o m e n t co- e f f i c i e n t s a s t h e f l a p d e f l e c t i o n s a r e i n c r e a s e d , The v a r i a t i o n o f w i t h B e y n o l d s number i s CLmax g i v e n i n f i g u r e 5 f o r b o t h t h e w i n g a l o n e a n d t h e w i n g w i t h f l a p s . T h e s e c u r v e s show some s c a l e e f f e c t f o r b o t h c o n d i t i o n s a n d a n i n c r e a s e of C o v e r s i m i l a r i n s t a l - 'max i n r e f e r e n c e 1.
l a t i o n s . o n . t h e r e c t a n g u l a r w i n g d e s c r i b e d The i n c r e m e n t of maximum l i f t . c o e f f i c i e n t A C L o c c a - . max s i o n e d b y t h e u s e of t h e f l a p s i n d i c a t e s - a - c h a n g e w i t h R e y n o l d s number a s shown b y f i g u r e 6 . T h i s r e s u l t i s somewhat d i f f g r e n t f r o m t h a t o b t a i n e d w i t h t h e r e c t a n g u l a r w i n g m e n t i o n e d p r e v i o u s l y w h e r e l i t t l e c h a n g e was n o t e d , The v a r i a t i o n of A C L w i t h f l a p d e f l e c t i o n i s m a x g i v e n i n f i g u r e 7. A t t h e maximum d e f l e c t i o n t e s t e d ( 6 0 ° ) , t h e c u r v e i s s t i l l i n c r e a s i n g s o m e w h a t ; h o w e v e r , . i t i s b e g i n n i n g t o l e v e l o f f , i n d i c a t i n g t h a t h i g h e r d e f l e c t i o n s w o u l d g i v e o n l y a s m a l l i n c r e a s e i n t h e maximum l i f t c o e f - f i c i e n t , % 2 - j S t a l l i n g C h a r a c t e r i s t i c s The s t a l l d i a g r a m s f o r . t h e p l a i n w i n g a n d f o r t h e w i n g w i t h p a r t i a l - s p a n s p l i t f l a p d e f l e c t e d 60' a r e g i v e n i n f i g u r e s 8 a n d 9. T h e s e d i a g r a m s show t h a t t h e s t a l l b e g i n s on t h e r e a r p o r t i o n of t h e w i n g d i r e c t l y b e h i n d t h e w i n g s u p p o r t s f r o m whence i t s p r e a d s f o r w a r d a n d o u t - ward w i t h i n c r e a s e of a n g l e of a t t a c k . The a d d i t i o n of t h e f l a p d e l a y s t h e b e g i n n i n g of t h e s t a l l somewhat, b u t c o m p l e t e s t a l l d e v e l o p s more r a p i d l y a n d o c c u r s a t a .
l o w e r a n g l e of a t t a c k t h a n w i t h t h e p l a i n wing. As was t r u e of t h e r e c t a n g u l a r low-diag wing d e s c r i b e d i n r e f e r - e n c e 1, t h e a d d i t i o n of t h e f l a p i n d u c e s a n a p p r e c i a b l e i n f l o w o v e r t h a t . p o r t i o n . of t h e wing n o r m a l l y o c c u p i e d by t h e a i l e r o n s . I t may b e n o t e d t h a t t h e r i g h t s i d e o?
t h e wing a p p e a r s t o s t a l l f i r s t , b u t t h i s may be due t o
a s l i g h t asymmetry of t h e wing r a t h e r t h a n someth-ing of a n a e r o d y n a m i c n a t u r e . M o r e o v e r , s i n c e t h e i n v e e t i g a t i o n was c o n d u c t e d i n a c l o s e d - t h r o a t ' wind t u n n e l , t h e r e s u l t s s h o u l d b e somewhat c o n s e r v a t i v e compared w i t h t h o s e i n f r e e a i r .
. .
CONCL'US IONS 1, The a d d i t i o n of a s i m p l e s r ~ l i t f l a p t o a t a p e r e d wing h a v i n g NACh low-drag s e c t i o n s g i v e s a e r o d y n a m i c c h a r a c t e r i s t i c s t h a t compare f a v a r a b l y w i t h t h o s e o b t a i n e d w i t h s i m i l a r i n s t a l l a t i o n s on w i n g s . h a v i n g c o n v e n t i o n a l s e c t i o n s .
2 . The i n c r e m e n t of maximum l i f t c o e f f i c i e n t due t o he s p l i t f . l a p on t h e wing t e s t e d was f o u n d t o v a r y some- h a t w i t h R e y n o l d s number. The minimum e f f e c t o c c u r s w i t h t h e s m a l l e s t f l a p d e f l e c t i o n a n d i n c r e a s e s a s t h e d e f l e c - t i o n i n c r e a s e s .
3. The C L m a x of t h e wing a l o n e i s 1 , 4 9 a t a R e y n o l d s number of 4 , 6 0 0 , 0 0 0 ; w h e r e a s w i t h t h e p a r t i a l - s p a n s p l i t - f l a p a r r a n g e m e n t t h e v a l u e i s 2 . 2 2 a n d w i t h t h e f u l l - s p a n a r r a n g e m e n t , 2.80.
4 . The p l a i n wing a p p e a r s t o have f a v o r a b l e s t a l l i n g c h a r a c t e r i s t , i c s t h a t a r e a o t a p p r e c i a b l y a L t e r e d b y t h e a d d i t i o n of a s p l i t f l a p , e v e n t h o u g h c o m p l e t e ' s t a l l ac- c u r s e a r l i e r w i t h t h e f l a p . ..
L a n g l e y Memorial A e r o n a u t i c a l L a b o r a t o r y , N a t i o n a l A d v i s o r y Committee f o r A e r o n a u t i c s , L a n g l e y F i e l d , V a , REFERENCE, 1. Muse, Thomas C . , a n d N e e l y , X o b e r t H e : Wind-Tunnel I n v e s t i g a t i o n of a n NACA 66,2--216 Low-Drag Wing w i t h S y l i t F l a p s of V a r i o u s S i z e s . NACA A . C . R . S e p t . 1 9 4 1 .
0.200 s p l i t f l a .3Oc Fowler il Maxwell s l o t . n w -
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b L T A ~ W ~ I , - aKDTNPiTES FOR NACA 66,2-216 AIRFOIL SECTION
T , @ & ? * , - ORDIE.~TES/ FCX ITACI-, 66,2-116 AImOIL SCTION
p t a , t i o n s and o r d i n a t e s i n percent; of wing chord..
@ t a t i o n s and o r d i n a t e s i n p e r c e n t of wing chore%]
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2 .632 2 .862 $2 g:, 50,023 55.073 60.141 65,191 70.198 75.181 SO, 149 85.106- 9O,O61 95 0 021 100*000 Fig. 1 Fig. 3a
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t -4 0 4 8 12 16 20 24 Ang/e o f of fack, a, deg ( a ) R = 2,600,000.
F i s r e 3(a t o c).- Aerod:rrarnic c h a r a c t e r i s t i c s of an NACA 66 s e r i e s l o w - d r a g t a p e r e d w i n g w i t h 0 . 2 0 ~ s p l i t flap.
Fig. 3b NACA f -4 0 4 8 2 16 20 24 Angle o f of fork, a, deg ~ h q / e o f offack, a , deq ( b ) R = 1,700,000.
Figure 3(b).
U C A Fig. 3c Fig, 4 NAC A 0 0 0 u3 - 4 0 U 0 4
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cd k a I a , ,-I .rl Figo. 5,6 NAG A Figure 5,- Variation of maximum Figure 6.- OuiesPioa of increment o f maximum l i f t coef- l i f t c o e f f i c i e n t with f i c i e n t with Reynolds number of Reynoldo number of an N A C A 66 N A C A 66 e e r i e % low-dr&$ tapered s e r i e s low-drag tapered wing wing with 0.80~ s p l i t flaps.
with a 0 . 2 0 ~ s p l i t f l a p .
Fig. 7 F/op deflection, df , d e g Figure 7 . - Effect of f l a p deflection on the increment of maximum l i f t coefficient for o 0 . 8 0 ~ partial-apW r@lbt f l a p on sbn NACP 66 series low-brag tapered wing.
MACA Fig. 8 I
c t = ~ l " &= 1.26 F19"i-e 9.-Stoll diagrams of an W A low-drag
tapered wln wifh a 0 . 2 0 ~ prttcil-span 9sp\if f l o p : b+ 1 600:
5"
R .l,bOO,OOO a