What flying-machine principle did Leonardo da Vinci study with his ornithopter designs?

Leonardo da Vinci studied flapping wings in his ornithopter designs.

An ornithopter is a flying machine that generates lift through wings that flap, broadly imitating birds or bats. Leonardo investigated this idea in numerous drawings and notes, especially during the late fifteenth and early sixteenth centuries. He examined bird anatomy, wing structure, air resistance, and the relationship between movement and lift.

His designs included devices with human-powered wings, but a person could not supply enough power through Renaissance mechanisms to achieve sustained flight. Leonardo also considered gliding and the possibility of using a pilot’s body movements to control a machine.

Leonardo’s ornithopters were not successful aircraft, and they should not be confused with helicopters or airplanes. Their importance lies in the systematic way he studied natural flight. His observations helped establish a tradition of engineering flight by analyzing forces rather than merely copying a bird’s appearance.