Computation of the roll characteristics of a finned projectile

Abstract : The Computational Aerodynamics Branch, Launch and Flight Division has been actively developing the capability to predict the aerodynamics of US Army projectiles using Computational Fluid Dynamics (CFD) techniques. Currently under development is the capability to predict the supersonic aerodynamics of finned projectiles such as kinetic energy (KE) penetrators. In the current research effort, several important aerodynamic parameters which influence the roll characteristics of a fielded kinetic energy projectile (M735) have been predicted using CFD techniques. These parameters include the roll producing moment (at zero spin rate), the roll damping moment, and the equilibrium spin rate, defined as the spin rate for which the net roll moment is zero. Viscous CFD computations have been performed over a range of Mach numbers and spin rates using the US Army's Cray-2 supercomputer located at the Ballistic Research Laboratory. The computed results have been used to benchmark and validate engineering approaches for computing these aerodynamics coefficients.