Power System Characterization and Flight Testing of a >55lb Hybrid-Electric Multirotor

Hybrid electric propulsion is a promising technology to enable new aircraft configurations with excellent overall vehicle performance. Electric propulsion enables new types and configurations of rotorcraft, but the poor energy density of batteries has limited the overall endurance of electrically propelled aircraft. A hybrid architecture can take advantage of the high energy density of chemical/liquid fuels; but also utilize the advantages of electric propulsion technology. This advantage of a hybrid system can only be realized if the hybrid system is light enough and efficient enough. If not done in a highly optimized way the hybrid system can end up being too heavy and too inefficient - the worst of both worlds instead of the best of both worlds. This paper presents details of the LaunchPoint EPS hybrid electric power system and results of flight tests showing aircraft endurance improvements of at least 4 times longer over a pure electric version of the same aircraft.