Prediction of Roll Moments on Finned Bodies in Supersonic Flow

Abstract

A method is presented for predicting roll moments produced by fins on missile bodies at high angle of attack in supersonic flow. The missile configurations are assumed to have pointed noses and circular cylindrical bodies. The effect of the body induced flow on the roll moments produced by fins is studied. Particular attention is given to the body vortices and separated flow on the lee side of the missile. A cruciform fin configuration with fins having rectangular planform is analyzed. A previously developed flow model is used to calculate the flowfield produced by the body. The body flowfield experienced by the fins is used with a quasi-linear lifting theory to predict the roll moments. Results are presented for the fin cant, induced roll, and roll damping moments. The roll moment predictions are compared with experimental data and generally good agreement is obtained. The physical causes of the observed nonlinear roll phenomena are discussed.