Stability Derivatives of a Delta Wing with Straight Leading Edge in the Newtonian Limit

Abstract

This paper presents an analytical method to predict the aerodynamic stability derivatives of oscillating delta \ud wings with straight leading edge. It uses the Ghosh similitude and the strip theory to obtain the expressions for\ud stability derivatives in pitch and roll in the Newtonian limit. The present theory gives a quick and approximate \ud method to estimate the stability derivatives which is very essential at the design stage. They are applicable for \ud wings of arbitrary plan form shape at high angles of attack provided the shock wave is attached to the leading \ud edge of the wing. The expressions derived for stability derivatives become exact in the Newtonian limit. The \ud stiffness derivative and damping derivative in pitch and roll are dependent on the geometric parameter of the \ud wing. It is found that stiffness derivative linearly varies with the pivot position. In the case of damping \ud derivative since expressions for these derivatives are non-linear and the same is reflected in the results. Roll \ud damping derivative also varies linearly with respect to the angle of attack. When the variation of roll damping \ud derivative was considered, it is found it also, varies linearly with angle of attack for given sweep angle, but with \ud increase in sweep angle there is continuous decrease in the magnitude of the roll damping derivative however, \ud the values differ for different values in sweep angle and the same is reflected in the result when it was studied \ud with respect to sweep angle. From the results it is found that one can arrive at the optimum value of the angle of \ud attack sweep angle which will give the best performance