Optimal design and endurance estimation of propulsion system for electric-powered unmanned aerial vehicle

For small electric-powered unmanned aerial vehicles (EPUAV), endurance performance largely depends on propulsion system. To improve EPUAV endurance, the electric-powered propulsion system was designed optimally. Meanwhile EPUAV endurance formula was presented. Based on vortex theory, a small screw propeller was designed optimally using genetic algorithm. A series of predicted motors were tested by dynamometer in order to match the optimized screw propeller effectively. The influences of discharged rating and voltage drop for lithium-ion battery were considered. Then a math model of battery discharge time was deduced while the battery output power was kept as constant. According to the optimal propulsion system and battery model, the EPUAV endurance formula was presented for cambered wing. Flight tests of a flying wing EPUAV indicate that optimized propulsion system operates more effectively after an optimal design. There exists approximately 12% error between flight tests and theoretical estimation. Within permissible error, good agreements have been obtained.