升力体飞行器能量近似最优倾斜转弯飞行策略

升力体飞行器返回地球大气层内时受到热流、动压及过载等约束条件，为使得飞行器在倾斜转弯飞行过程中能量损失最小，需要研究一种能量最优的倾斜转弯机动飞行策略。本文的主要研究内容包括：从再入动力学模型出发，分析了升力体飞行器倾斜转弯的弹道特性，推导了终端速度与倾斜转弯幅度相关的解析解，提出了一种多约束条件下能量近似最优的倾斜转弯飞行策略；为进一步验证飞行策略的能量近似最优性，建立了能量最优的非线性轨迹优化模型，通过高斯伪谱法进行求解，获得能量最优的飞行轨迹。仿真结果表明，该飞行策略与优化方法获得的结果高度一致，并且该方法求解效率更高，工程应用性更强。

Energy suboptimal flight strategy of bank-to-turn maneuver for lifting vehicle

When lifting vehicle is returning into earth's atmosphere, some path constraints including heating rate, dynamic pressure and overload should be enforced strictly. In order to reduce the energy losing during the performance of bank-to-turn maneuver, it is necessary to develop a suboptimal flight strategy. The main research contents of this paper are as follows. The trajectory characteristic of bank-to-turn maneuver is analyzed via studying the entry dynamics. The analytical solution to terminal velocity at the special terminal heading angle is derived. Furthermore, a suboptimal flight strategy, which considers the path constraints, is proposed based on this analytical solution. In order to verify the optimality of this flight strategy, a trajectory optimization problem is formulated so as to provide optimal energy trajectory. Then, Gauss pseudospectral method is used to solve this problem. The results show that both trajectories are highly consistent, and the flight strategy is more efficient and has greater engineering applicable values.