Static Longitudinal Stability and Control Characteristics of a 1/16 -Scale Model of the Douglas D-558-II Research Airplane at Mach Numbers of 1.61 and 2.01

A n investigation has been conducted i n t h e Langley 4by &-foot supersonic pressure tunnel at Mach numbers of 1.61 and 2.01 t o determine 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 c o n t r o l c h a r a c t e r i s t i c s o f a 1/16scale model o f t h e Douglas D-558-11 research airplane.The r e s u l t s o f the investigation indicated a high degree of longit u d i n a l s t a b i l i t y t h a t d e c r e a s e d slightly with increasing Macb.number and Hft c o e f f i c i e n t .The t r i m lift coefficient obtained with the m a x i m m h o r i z o n t a l -t a i l d e f l e c t i o n o f -6O was 0.557 at a Mach number of 1.61 and 0.425 at a Mach number of 2.01.The m a x i m u m t r i m e d l i f t -t o -d r a g r a t i o was about 3.2 at a Mach number of 1.61 and about 3 at a Mach number o f 2.01.For a constant wing loading the control position required to t r i m with increasing Mach number ( s t i c k -p o s i t i o n s t a b i l i t y ) was found to change f r o m an u n s t a b l e t o a s t a b l e v a r i a t i o n w i t h i n c r e a s b g a l t i t u d e .