Dynamic Response to Canard Control and Gravity for a Dual-Spin Projectile

摘要

Existing literature has shown that spin-stabilized projectiles respond out-of-phase to control force that is applied at the nose of projectile. However, this conclusion was made according to some assumptions or specific conditions. Taking a dual-spin-stabilized projectile with canards as the object of study, this paper seeks to explore a deeper understanding of dynamic response to control input in another particular situation by considering the coupled effect of canard control and gravity. By establishing a linear model of the pitching and yawing motion based on a simplified seven-degree-of-freedom dynamic model for this projectile, approximate expressions that could predict the angle of attack after canard actuation were obtained. These effective formulas are used to indicate that, depending on the effect of gravity on trajectory, the swerve response due to identical canard control could be fundamentally different, especially with large amplitude of gravity-induced yaw of repose. The phase shift may vary substantially with different deflection angles of canards during the process of guidance and control. Moreover, a simple formula for estimating the critical equivalent deflection angle of canards was given. The results of this research are expected to be supplementary to those concerning flight dynamics of spin-stabilized projectiles concluded in current literature.