Dynamic stability analysis of flexible spinning flight vehicles under follower thrust

Effect of spinning speed in the dynamic analysis of flexible spinning flight vehicles is emphatically considered in this paper. Taking into account gyroscopic moment and follower thrust, motion equations are formulated and then dynamic stability is analyzed. The flexible spinning flight vehicle is simplified as non-uniform rotor structure with an attached mass. Given that shear deformation influences axial displacement, Timoshenko beam model is adopted by considering the effect of gyroscopic moment and follower thrust. Finally motion equations are established based on the finite element method to analyze impacts of factors such as speed, shear stiffness and attached mass, etc. on the stability of the system. A new phenomenon of modal coupling between rigid modal and elastic modal in the system of spinning flight vehicles is discovered under the influence of spinning speed. Results show that shear deformation has great influence on the critical thrust when shear stiffness value is small; magnitude and position of attached mass has certain impacts on critical thrust and instability region; bending modal and rigid modal of the non-uniform rotor system are generally induced to merge to a coupled modal, thus resulting in dynamic instability.