Leonardo da Vinci’s bat-inspired flying-machine design was an ornithopter. An ornithopter is an aircraft intended to fly by flapping wings, rather than by using fixed wings like an airplane or rotating blades like a helicopter.
Leonardo studied birds and bats closely and produced several flying-machine sketches during the late 15th and early 16th centuries. His proposed machine used a human pilot’s muscular effort to operate large wings. The drawings show how he tried to transfer observations from animal flight into a mechanical design.
Leonardo’s ornithopter was never a practical aircraft because human muscles cannot provide enough sustained power for a person-sized flapping machine. It is also distinct from his aerial screw, which used a rotating helical surface. Modern ornithopters exist as small experimental or model aircraft, but Leonardo’s version remained a design study.