A helicopter includes a propulsion system, gimbal assembly, and a controller. The propulsion system includes a first and second rotor assembly, wherein the first rotor assembly comprises a first motor coupled to a first rotor, the first rotor comprising a plurality of first fixed-pitch blades and the second rotor assembly comprises a second motor coupled to a second rotor, the second rotor comprising a plurality of second fixed-pitch blades. The second rotor is coaxial to the first rotor and is configured to be counter-rotating to the first rotor. The controller is communicably coupled to the gimbal assembly and is configured to provide instructions to at least one of the first or second gimbal motors in order to orient the plurality of first and second fixed-pitch blades into a position that permits wind to rotate the first and second fixed-pitch blades and thereby charge the power source.