Aurora Flight Sciences video of the first flight of its Excalibur experimental vertical takeoff and landing unmanned aircraft. The 13ft-long UAV is powered by a tilting jet engine and three battery-powered lift fans. The aircraft made its first hover flight, lasting just under 2min, at Aberdeen proving Gorund in maryland on June 24. Excalibur is a proof-of-principle testbed for a 400kt VTOL unmanned combat aircraft.