Low-speed wind-tunnel results for a thin aspect-ratio-1.85 pointed-wing-fuselage model with double slotted flaps

Results are presented of a wind-tunnel investigation a t low speeds of a thin aspect-ratio-1.85pointed-wing-fuselage model equipped with double s l o t t e d f l a p s , i n c l u d i n g t h e e f f e c t s of a s t r a i g h t and a d e l t a h o r izontal t a i l on t h e s t a t i c l o n g i t u d i n a l s t a b i l i t y and t h e e f f e c t of a d e l t a v e r t i c a l t a i l on t h e s t a t i c l a t e r a l s t a b i l i t y .The r e s u l t s i n d ic a t e d t h a t f l a p e f f e c t i v e n e s s i n c r e a s e d w i t h i n c r e a s e o f f l a p d e f l e c t i o n up t o 52.5'.For f l a p d e f l e c t i o n s g r e a t e r t h a n 52..5O, f l a p e f f e c t i v eness decreased with increase of flap deflection.With a f l a p d e f l e c t i o n of 52.5', t h e l i f t c o e f f i c i e n t a t an angle of attack of 0 ' was 0.66 and t h e maximum l i f t c o e f f i c i e n t was 1.53.Most of t h e l i f t -c o e f f i c i e n t increment a t an angle of a t t a c k of 0 ' held throughout the angle-ofattack range to near s t a l l .F o r l o n g i t u d i n a l s t a b i l i t y of t h e model with t h e double s l o t t e d f l a p s d e f l e c t e d , t h e s a t i s f a c t o r y l o c a t i o n f o r a s t r a i g h t or d e l t a h o r i z o n t a l t a i l was rearward and below the wing chord l i n e extended.However, t h e s t r a i g h t h o r i z o n t a l t a i l studied would not provide longitudinal trim.The d e l t a v e r t i c a l t a i l p r o v i d e d s t a t i cd i r e c t i o n a l s t a b i l i t y o f the model except at high l i f t c o e f f i c i e n t s and g e n e r a l l y i n c r e a s e d t h e e f f e c t i v e d i h e d r a l .