Unlimited endurance performance of solar UAVs with minimal or zero electric energy storage

Periodic optimal flight is a means contributing to achieve an unlimited endurance performance of solar-powered UAVs. The optimization goal of the treatment presented in this paper is to attain the capability to stay aloft with a minimum or even no solar energy to be stored in batteries for the flight during the night. It is shown that this is possible with an appropriate trajectory control. The periodicity of the optimized flight implies that the trajectory can be continued after a complete day-night cycle in the same manner as before. Realistic mathematical models of the UAV dynamics and the energy management system for an optimal solar power use are applied. Employing an efficient optimization method, results on periodic optimal UAV flight yielding the performance goal aimed at are presented. With a minimum or zero electric energy to be stored in batteries, the related weight penalty can be reduced or even avoided.