Guidance Scheme for Glide Range Maximization of a Hypersonic Vehicle

If the attack angle of a hypersonic vehicle maximizes the lift to drag ratio, the glide range in a vertical plane over the spherical Earth is nearly as far as the maximum-glide flight. And it's demonstrated by mathematical method in this article. But the law produces a poor damping of the phugoid oscillation. The article presents a scheme which is fit for the glide phase of a hypersonic vehicle. The path angle of a hypersonic vehicle is a negative feedback signal in this scheme. It hence produces a high degree of damping of the phugoid oscillation. When the path angle becomes steady and changes along the command path angle, the vehicle flies along the trajectory which maximizes the lift to drag ratio in the quasi-steady equilibrium condition. By increasing the negative feedback signal gain, it not only suppresses the oscillation, but also decreases the value of some physical variables, such as the maximum heating rate. In the example, it is showed that the simulation results of a hypersonic vehicle are similar with the optimal control results.