What winged machine did Leonardo da Vinci sketch for human-powered flight?

Leonardo da Vinci sketched an ornithopter as a machine for human-powered flight.

An ornithopter is an aircraft that flies by flapping wings, imitating the motion of birds or insects. Leonardo studied bird anatomy, wing structure, and the movement of air while developing several flying-machine designs. His drawings include mechanisms in which a pilot would use pedals, handles, or body movement to operate wings.

Leonardo's ornithopters were imaginative studies rather than successful aircraft. A human pilot could not generate enough power with Renaissance materials and muscle strength to sustain the required flapping motion. The limitation was not simply a lack of skill: human muscles have too little power relative to body mass for this type of flight.

The word ornithopter comes from Greek roots meaning “bird” and “wing.” Modern experimental ornithopters use motors or other power sources, while Leonardo's proposals are remembered mainly for connecting biological observation with mechanical design.