Effect of Ablation-Induced Roll Torques on Re-entry Vehicles

Abstract

The results of a re-entry vehicle flight test program to evaluate the roll-producing effect of an ablating tapewrapped carbon phenolic heat shield are presented. Included is a description of the thermal shield construction, which reveals the presence of small aerodynamic surfaces. Exposed by the ablation process during severe reentry environment, these surfaces are capable of producing significant rolling moments. Instrumentation onboard the flight vehicle, designed to evaluate the aerodynamic and thermal response, indicated that the desired flight environment was achieved and that there was sufficient ablation to generate roll torque. A discussion of theoretical methods to predict the rolling moment coefficients is presented, as well as a comparison of the predicted coefficients with flight data. The vehicle was recovered intact, and the postflight inspection is described.