The flying-machine type Leonardo da Vinci studied by imitating a bird’s wings is an ornithopter.
An ornithopter is an aircraft designed to fly by flapping wings, rather than by using fixed wings or a powered rotor. Leonardo examined birds and bats and produced many sketches investigating how their wings generated lift and thrust. His notebooks show articulated wings, frames, and mechanical systems intended to reproduce biological flight.
Leonardo’s ornithopter studies belong mainly to the late fifteenth and early sixteenth centuries. He understood that wing shape, air movement, balance, and weight were central problems, but the human-powered machines he imagined were not capable of sustained flight. A person could not generate enough power through leg or arm motion to flap wings of the required size.
The term ornithopter comes from Greek words meaning bird and wing. It includes both theoretical machines and later experimental aircraft. Leonardo’s work is important because it treated flight as an engineering subject based on observation, even though his bird-like mechanisms did not become practical aircraft.