Effect of Angle of attack on Stability Derivatives of a Delta wing in Hypersonic Flow with Straight leading edge

Abstract

In the present paper effect of angle of attack on stability derivatives in pitch of delta wing for the attached shock case is been studied. A strip theory is used in which strips at different span-wise locations are independent. This combines with the similitude to give a piston theory. In the present theory, the similitude, and the piston theory have been extended to a flat wing with straight leading edges. The linear dependence of the stiffness derivative is seen for all parameters of the present study, however for higher angle of attack the nonlinearity in the stiffness derivative is observed; since at very high angle of attack the flow separation will take place. It is also, observed that when angle of attack is small the variation in the stiffness and damping derivative in pitch remains in the range around thirty to thirty six percent, later for higher angles of attack, namely ten to twenty five degrees this variation in the stiffness and damping derivatives is in the range from ten to fifteen percent; and for angles of attack beyond twenty five degrees it remains independent of angle of attack in spite of variations in the Mach number and angles of attack. When the stiffness and damping derivatives are considered for h = 0.6 which; is also happens to be the center of pressure and for some cases the aerodynamic center the independency with angle of attack has been observed. The present theory is valid for large angle of incidence and Mach number. The present theory is simpler than both Lui and Hui and Hui et al and brings out explicit dependence of the stability derivatives on the similarity parameter. The present theory is not valid for a detached shock case. Future research can be done by taking into account the effects of shock motion, viscosity, wave reflections and the real gas effects.