Leonardo da Vinci sketched an ornithopter, an aircraft intended to fly by flapping wings like a bird.
Leonardo studied birds and bats closely and produced many flying-machine drawings during the late fifteenth and early sixteenth centuries. His ornithopter concepts generally placed a human pilot inside or beneath a large wing structure. Mechanical linkages were intended to transfer the pilot’s leg or arm movements to the wings.
The word ornithopter comes from Greek roots meaning bird and wing. Unlike a glider, which depends on fixed wings, an ornithopter is defined by flapping wings. Leonardo’s designs therefore belong to the history of flapping flight, even though they were not practical human-powered aircraft.
Leonardo correctly recognized that flight required more than simply copying a bird’s outline. He considered lift, balance, wing shape, and the strength of materials. However, human muscles cannot supply enough sustained power for a large flapping aircraft, so his ornithopters never achieved controlled flight.