Leonardo da Vinci designed an ornithopter, a human-powered winged machine inspired by bird flight.
Leonardo's notebooks contain many studies of birds, wings, feathers, and air resistance. His ornithopter concepts generally used a pilot lying or standing inside a frame while operating wings through pedals, levers, or other mechanical linkages. The moving wings were intended to imitate the flapping action of birds.
Leonardo understood that birds benefit from lightweight bodies, strong muscles, and carefully shaped wings. A human pilot, however, could not supply enough power through contemporary mechanisms to sustain this type of flight. No Leonardo ornithopter is known to have flown successfully.
An ornithopter is any aircraft that flies by flapping wings, whether powered by a person, engine, or another mechanism. It is therefore broader than a Leonardo-specific machine. His sketches are historically important because they combine anatomical observation with systematic attempts to explain and reproduce natural flight.