A Human-Powered Aircraft - A human-powered aircraft is an aircraft powered by direct human energy and the force of gravity; the thrust provided by the human may be the only source. The “Snowbird” ornithopter, as it was named, has a 32-meter wingspan and weighs 42 kilos. It flew for a distance of 145 meters, for 19 seconds, at the speed of 25 km/h, without losing speed or altitude.