A new guidance scheme has been developed for the terminal phase of an unpowered reusable launch vehicle that has known limited bank capabilities. Reduced bank angle magnitude may be the result of actuator failures, and in such cases a vehicle will have difficulty performing the required heading change before approach and landing. A vertical guidance law controls dynamic pressure, and attempts to track the minimum dynamic pressure boundary to extend the ground track and maximize the turning rate. Lateral guidance uses a bank reversal to widen the turn radius and spiral in to a heading-alignment circle. The guidance algorithm iterates on two parameters (bank-reversal switch time and heading-alignment circle location), and selects the best values by propagating several trajectories to the desired approach and landing energy state. The effectiveness of the guidance algorithm is demonstrated by several numerical simulations, which show that the guided vehicle is able to successfully reach the desired approach and landing interface state with bank limitations as low as 18 deg.
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