Leonardo da Vinci’s winged flying-machine concept is an ornithopter, a craft intended to fly by flapping wings. The word comes from Greek roots meaning “bird” and “wing.”
Leonardo studied birds, bats and human anatomy, then sketched machines with large wings operated by a pilot’s arms or legs. His notebooks include several arrangements of frames, cords and hinges designed to imitate animal flight.
The machines were not powered by engines, and human muscle could not provide enough energy to flap wings of the proposed size. For that reason, Leonardo’s ornithopters remained studies rather than successful aircraft. They nevertheless influenced later thinking about biomechanics and flight.
An ornithopter is not the same as Leonardo’s aerial screw, which uses a rotating helical surface, nor his glider-like wing designs. The defining feature is flapping propulsion, whether produced by a person, an engine or another mechanism.