A three-dimensional trajectory planning algorithm is proposed for the terminal area energy management (TAEM) phase of an unpowered reusable launch vehicle (RLV). Firstly, a reference dynamic pressure profile which characterizes the longitudinal motion is conceived on the basis of the maximum dive and maximum glide capabilities. Secondly, a reference ground-track path is developed, which is composed of four flight segments determined by the location, the size, and the turning mode of a heading alignment cone. Then, the RLV motion equations modeled by kernel extraction protocol (KEP) are numerically solved via secant iteration method, according to the knowledge of the pre-designed dynamical pressure profile and the ground-track path. Finally, a down-track correction scheme is designed to correct the down-track position along the runway centerline. Numerical simulations are conducted to illustrate the effectiveness of the proposed trajectory planning algorithm.
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