Preliminary Design of a Highly Efficient VTOL System Based on Tethered Fixed-Wing Aircraft

2016, to form their 34th Student Design Competition around designing an aircraft capable of hovering for a duration of 24 hours with a 176 lb (80 kg) payload. This paper presents the preliminary design of the Swarm, a configuration of the Electric Powered Reconfigurable Rotor (EPR2 ) concept, drafted by the joint Universite de Sherbrooke and Georgia Tech team. The Swarm, comprised of a central fuselage tethered to three electrically propelled unmanned fixed-wing aircraft flying in a circular trajectory, achieves its goal through rotor reconfiguration. Throughout the flight, the fixed-wing aircraft modify their trajectory and airspeed to optimize performance and minimize fuel burn rate. A hybrid-electric powerplant in the fuselage supplies power via conductive tethers to the fixed-wing aircraft. The design and reconfiguration were optimized using a 2-step time-marching optimization. The designed system greatly exceeds the competition requirements by accomplishing 31 hours of hover flight using readily available technologies and COTS components. The Swarm, weighing a maximum of 2,700 lb (1,224 kg), requires only between 62 and 120 hp (46-89 kW) to perform hover out of ground effect. Safety, reliability and maintenance analyses were also conducted, in addition to estimating production and operational costs of the system.