The present disclosure relates to an unmanned aerial vehicle (UAV) able to harvest energy from updrafts and a method of enhancing operation of an unmanned aerial vehicle. The unmanned aerial vehicle with a gliding capability comprises a generator arranged to be driven by a rotor, and a battery, wherein the unmanned aerial vehicle can operate in an energy harvesting mode in which the motion of the unmanned aerial vehicle drives the rotor to rotate, the rotor drives the generator, and the generator charges the battery. In the energy harvesting mode regenerative braking of the generator reduces the forward speed of the unmanned aerial vehicle to generate electricity and prevent the unmanned aerial vehicle from flying above a predetermined altitude.