Design of hybrid electric propulsion system for long endurance small UAV

Nowadays, all countries around the globe face environmental problems. Emissions from ground and aerial vehicles that consume fossil fuel contribute a lot to air pollution. As technology development of green energy source, low-emission vehicles are realizable for transportations. In aviation, a new concept low-emission eco-friendly UAV, which will be able to accomplish long-endurance missions with few or no emissions, is under development. A hybrid power system with solar cells and fuel cells, which are renewable and clean power sources, has been chosen to be the electric propulsion of the UAV. Comparing with the hours' loitering time of existing electric small UAVs, the hybrid system will make it possible to surveillance over one day or more, which is rightly required for aerographic, geographic researches and other applications. The design of hybrid propulsion system will not only require the technique of every single power source, but also the modeling, simulation, integration and experiment of the entire system. To confirm the feasibility of solar cells and the carrier's aerodynamic, a radio controlled solar powered model plane was designed, manufactured and flown. The modeling of a hybrid power system is studied, and a series of analysis and tests have been carried out. The design criteria and development process of a hybrid electric powered long-endurance small UAV are discussed in this paper.