An unmanned aerial vehicle (UAV) in the form of a “tail sitter” flying wing adapted for vertical take off and landing and transitions between flight as a helicopter and wing-borne flight. The vehicle is electrically powered from onboard batteries and equipped with rotors on miniature helicopter rotor heads at the tips of the wing for both lift, during take off and landing, and forward thrust. In planform the wing comprises, to each side of its longitudinal axis, an inner section with swept back leading and trailing edges, and an outer section with a leading edge more perpendicular to the longitudinal axis, being only mildly swept back or substantially unswept, and a swept forward trailing edge.