Leonardo da Vinci sketched an ornithopter as a human-powered aircraft with flapping wings.
The word ornithopter comes from Greek roots meaning “bird” and “wing.” Leonardo studied birds closely and imagined that a person could generate lift by operating large wings through pedals, levers, and pulleys. His surviving drawings show several possible mechanisms rather than one finished, tested aircraft.
Leonardo understood that flight depended on lift, balance, and the movement of air, but human muscles cannot supply enough power for a practical flapping aircraft of the size he proposed. His designs therefore remained theoretical. They are nevertheless important in the history of aviation because they combine biological observation with mechanical engineering.
An ornithopter is not the same as a glider: a glider has fixed wings and relies on air currents, while an ornithopter produces thrust by moving its wings. Leonardo’s flying-machine studies also included devices with fixed wings and a screw-like rotor.