Human powered aircraft

A human-powered aircraft (HPA) is an aircraft belonging to the class of vehicles known as human-powered transport. As its name suggests, HPAs have the pilot not only steer, but power the aircraft (usually propeller-driven) by means of a system similar to a bicycle or tricycle: a pair of pedals, moved by the pilot's feet that turns a gear, which then moves a bicycle chain, which then rotates a smaller gear, which turns a vertical shaft that either turns a set of bevel gears, which turns another, horizontal shaft that ultimately turns a propeller, or in the case of earlier prototypes, an ornithopter mechanism. Often, a hybrid system is used; where during a certain amount of time pedaling, it would charge a battery, which would, at the push of a button, power an electric motor that is connected to the same horizontal shaft as the propeller. Human-powered aircraft have been successfully flown over considerable distances. However, they are still primarily constructed as engineering challenges rather than for any kind of recreational or utilitarian purpose.