Design of emergency landing region and landing trajectory for unpowered aircraft

Against the background of forced landing of unpowered aircraft caused by engine failure, this paper presents a design of the emergency landing region (ELR) and landing trajectory. First, the concept of ELR is introduced as the set of landing points within which an unpowered aircraft can achieve a soft landing. ELR is modeled using the optimal control method and computed through the hp-adaptive pseudospectral method. The features of ELR and the key factors that influence it are analyzed by theoretical deduction combined with simulation, and a simple approximation method to calculate ELR is obtained accordingly. Then, an emergency landing site is selected according to ELR, and the corresponding landing trajectory is designed through the optimal control method. Simulation results demonstrate that the establishment and analysis of ELR have great reference value for selecting an emergency landing site quickly, and the designed landing trajectory can guide an unpowered aircraft to a safe landing.