Leonardo da Vinci studied the ornithopter, a flying-machine concept powered by flapping wings.
Leonardo filled notebooks with observations of birds, bats, and the mechanics of flight. His proposed ornithopters generally used wings moved by human muscular effort or mechanical linkages, rather than engines.
The word ornithopter comes from Greek roots meaning “bird” and “wing.” Unlike a glider, which stays aloft with fixed wings, an ornithopter is defined by flapping wings that imitate the motion of birds or insects.
Leonardo’s designs were important studies of aerodynamics, anatomy, and mechanical transmission, but they were not known to have flown. Human strength is insufficient to power a bird-sized flapping aircraft with the efficiency needed for sustained flight.