Aeroelastic effects on the roll characteristics of a wraparound fin projectile

Abstract

The roll characteristics of a projectile with wraparound fins in the supersonic flow region an! analyzed considering the flexibility of the fins. Because of the inherent spin, wraparound fins are subjected to both aerodynamic and centrifugal forces. The aerodynamic force is computed by solving the Euler equations in a body-fixed rotating coordinate frame. A finite element structure modeling and static deflection calculations, resulting from the centrifugal force and the aerodynamic force of the wraparound fin, have been made. The equilibrium spin rate, defined as the spin rate for which the net roll moment is zero, is selected as the major aeroelastic roll parameter. The equilibrium spin rates at various velocity indices and mass ratios are computed. As velocity index or dynamic pressure increases, the equilibrium spin rate increases. The increase of mass ratio or fin mass increases the stiffness of the fin and decreases the effect of aerodynamic force on the equilibrium spin rate.