What type of machine did Leonardo da Vinci sketch with flapping wings?

Leonardo da Vinci sketched an ornithopter, a machine intended to fly with flapping wings.

The word ornithopter means a heavier-than-air aircraft that gains lift and propulsion by flapping wings. Leonardo studied birds and bats extensively and drew several human-powered flying machines whose wings were meant to imitate animal flight. His designs included frameworks, wing membranes, and mechanisms for transferring motion from the pilot’s arms or legs.

Leonardo recognized that human muscles alone would not easily produce the power required for a large flapping aircraft. He nevertheless investigated wing shape, air resistance, balance, and control in ways that anticipated later aeronautical study.

An ornithopter is different from a glider, which relies on existing air currents and does not flap its wings. Leonardo’s flying-machine drawings were important engineering investigations, but none is known to have flown successfully as designed.