Angle-of-attack convergence and windward- meridian rotation rate of rolling re-entry vehicles

Abstract

Abstract : A simple expression is derived for the influence of roll acceleration on the angle-of-attack convergence of rolling reentry vehicles with pitch or yaw damping. Also included is an analysis of the windward-meridian rotation rate of the rolling vehicle, which is coupled through the gyroscopic equations of motion to the angle of attack and roll rate. It is found that two modes of motion exist for which the windward meridian is generally oscillatory in one mode and rotary in the other (i.e., the vehicle either oscillates about its roll axis relative to the wind or rotates continuously in one direction). The mode of motion depends on the initial reentry conditions, and it is shown that a roll- induced instability can occur whereby the motion changes from the oscillatory mode to the more stable rotary mode. The analytical approximations are compared with computer solutions of the complete equations of motion.