Closed-form approximate solutions are derived to predict 3-Dimensional (3-D) atmospheric gliding trajectory of Hypersonic Glide Vehicle (HGV) accurately under high-maneuver flight condition where the lateral maneuvering range can be up to 4000 km. By contrast, the valid maneuvering range for the existing analytical solutions is less than 1500 km. However, high-intensity maneuver makes the motions in longitudinal and lateral planes seriously coupled and thus greatly increases the nonlinearity of flight dynamics. For the sake of simplification, a new flight dynamics model based on generalized longitude and latitude is introduced according to the trajectory characteristics. Then the dynamics model is simplified reasonably by giving full consideration to the coupling of the longitudinal and lateral motions as well as the effect of the curvature and rotation of Earth. The simplified model is still very complicated. Subsequently, by the skillful use of the perturbation technique, the model is further decomposed into three sub-systems that can be solved analytically in a tricky way, and thus the closed-form solutions are obtained successfully. As verified by the simulation results, the accuracy of the new solutions is much higher than the existing solutions in the case of high-maneuver flight.

Analytical entry guidance is designed to control the atmospheric gliding of a hypersonic glider. The guidance uses only approximate analytical solutions for a 3-D hypersonic gliding trajectory to fast plan reference trajectory onboard and thus has an extremely high computational efficiency. To reduce the amount of calculation, the adopted analytical solutions are improved first such that their coefficients depend only on generalized flight states. As the coupling of longitudinal and lateral dynamical equations is fully considered, the analytical solutions are of high accuracy but complicated, which consist of zeroth-and first-order solutions. To resolve the resulting difficulty of trajectory planning, an efficient scheme is proposed. In the first guidance cycle of steady glide, the scheme uses only the zeroth-order solutions to plan a trajectory rapidly. In the subsequent guidance cycles, the scheme first uses some profiles obtained from the previously planned trajectory to specify part of the coefficients of the zeroth-and first-order solutions in order to offset the impact of the equations coupling and then utilizes the complete solutions to update the trajectory by proposing a method based on a virtual endpoint of glide and virtual terminal crossrange, which can achieve a very small terminal heading error. The superiority of the guidance is demonstrated by conducting Monte-Carlo simulations.