Steady and Quasisteady Resonant Lock-In of Finned Projectiles

Equations of motion for a rolling finned projectile presented by an earlier investigator are corrected. Steady resonant lock-in solutions, both normal and reverse, are presented and their stability investigated. Two-dimensional topological models are constructed to explain how the occurrence of resonant lock-in depends on initial conditions. Results from numerical simulations are used to validate the suggested models. Quasisteady-state (QSS) resonant lock-in is shown to be possible for an unstable equilibrium solution at resonance. QSS solutions are found to lead to divergent yaw behavior typical of catastrophic yaw. It is suggested that catastrophic yaw can be demonstrated by modeling the effect of the nonlinear induced side forces and moments at resonance as a reduction in yaw damping.