Analysis of Complete Period Free Rotational Vibration Motion of a Tail-controlled Dual-spin Projectile
Recently,the guided transformation-based dual-spin configuration has become an effective means to improve the accuracy of ammunition strikes.To study the complete period free disturbance motion of a new type of tail-controlled dual-spin projectile,a 7 degrees of freedom ballistic model is established based on the ideal bearing assumption and non-roll coordinate system.The ballistic equations are linearized using the coefficient freezing method and small disturbance assumption.The complete period free disturbance motion equations are derived and represented in a state space form.A feature point on the ideal trajectory is selected.The motion modal for the complete period free disturbance near the feature point is obtained by numerical calculation method.The forms of free disturbance motion under different initial deviation values are discussed.The results indicate that the dual-spin projectile exhibits strong coupling characteristics in longitudinal and lateral motions.Similar to conventional projectiles,the free disturbance motion of dual-spin projectiles can still be divided into two stages:long period and short period.But the difference lies in the slow convergence of the angle of attack offset,and the modal amplitudes of different angle of attack offsets have different distribution patterns.The research results lay the foundation for further studying the angular motion and designing the guidance law.
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