Coning motion instability of spinning missiles induced by hinge moment

In the flight trials of a spinning missile, it was observed that an unexpected and unstable coning motion occurred after burnout. The missile was still in the free flight phase while the canards kept their original positions by servomechanisms. To address this unstable motion, the governing equation of the coning motion is derived and the dynamics of the fin actuators under the associated hinge moment is taken into account. The necessary and sufficient conditions of the coning motion stability are then analytically derived and further validated through nonlinear six degrees-of-freedom simulations for a representative scenario. It is demonstrated that the hinge moment may lead to the instability of spinning missiles under specific conditions. Finally, the effects of design parameters on the dynamic stability limit are discussed.