Evaluation of Energy Required for Flight by a UAV Fitted with a Variable-Span Wing Performing a Given Mission Profile

The present work addresses the energy consumption of a small UAV fitted with a conventional fixed wing and a variable-span wing (VSW) given a prescribed mission. The mission is chosen in such a way that the multirole capability of the VSW could be exercised. The power for each flight phase is estimated using experimental aerodynamic drag polars and by measuring the power drawn from the batery for various quasi-steady flight speeds. The takeoff energy and climb power are computed from measured inflight power data. The actuation system is also characterized inflight for both the fixed wing UAV and VSW UAV. From the propulsion power, actuation power and mission definition, the propulsion and actuation energy for each flight phase is calculated. It is concluded that the VSW fitted UAV has less overall energy consumption despite the increased aircraft weight and less efficent airfoil. The energy reduction occured only in the high speed condition but was so marked that offseted the increase in energy during the takeoff, climb and loiter phases.