Longitudinal characteristics of steady glide trajectory for hypersonic vehicle

In this paper, the steady glide trajectory (SGT) is proposed for the equilibrium glide problem with given continuously differentiable angle of attack (AOA) and bank angle profiles firstly. Then the analytical solutions of the SGT for altitude, flight path angle and vertical acceleration are obtained by regular perturbation method. Next the dynamic characteristics of the SGT are analyzed, and the simple but accurate formulas of the natural frequency and damping are achieved. After that, the trajectory simulations are conducted and the results show that the pure proportional feedback performs better than other schemes such as proportional and differential feedback. Finally, an improved trajectory damping control (ITDC) method is proposed, which can accurately control the damping of the glide trajectory.