Leonardo da Vinci designed ornithopters to investigate flight using flapping wings.
An ornithopter is a machine intended to fly by moving wings like a bird or insect. Leonardo’s notebooks contain many studies of bird anatomy, wing movement, balance, and the forces involved in flight. Some proposed designs placed a pilot inside a framework who would operate the wings with pedals, levers, or other mechanisms.
Leonardo understood that human muscle power would probably be insufficient for a large flapping aircraft. His work nevertheless helped connect careful observation of animals with mechanical experimentation. He did not achieve a documented powered human flight.
An ornithopter is different from a glider, which relies on fixed wings and forward motion rather than flapping. It is also different from Leonardo’s parachute, whose purpose was controlled descent rather than sustained flight.