Investigation on improving aerodynamics and flight performance for an unmanned aircraft with a span-extendable wing

Abstract

The foldable unmanned aerial vehicle can reduce the storage space and improve the platform adaptability. However, the conventional foldable wing aircraft is configured with a low aspect ratio, which leads to a high aerodynamic drag and limited flight endurance. In this study, a foldable wing unmanned aircraft that can increase its wingspan to improve aerodynamic performance and flight endurance is proposed. The aerodynamic characteristics and flight performance of the aircraft is evaluated using the computational fluid dynamic method. The numerical results show that the increased wingspan can effectively decrease the wingtip vorticity and aerodynamic drag. The fully-extended wing configuration achieves a lift-to-drag ratio of 16.72, which results in an increase of 36.94% than that of the non-extended wing. The flight endurance and range of the fully-extended wing configuration are 3.81 hour and 249.89 km, respectively, which creates 86.22% more endurance and 36.88% more range than the non-extended wing. To validate the feasibility of the proposed concept, a flight test was carried out and the flight performance was obtained from flight control system. The flight data corrects well with the numerical results, which proves the effectiveness and feasibility of the variable span-morphing wing in improving flight performance for unmanned aircraft.