Leonardo da Vinci designed an ornithopter, an aircraft intended to fly by flapping wings inspired by birds.
The word ornithopter comes from Greek roots meaning “bird” and “wing.” Leonardo studied bird anatomy, wing movement, balance, and air resistance while developing several flying-machine concepts during the late fifteenth and early sixteenth centuries.
His designs generally relied on a human pilot operating mechanical wings. Human muscles, however, cannot provide enough sustained power for a full-sized flapping aircraft, so none of Leonardo’s ornithopters became a practical flying machine.
Leonardo also explored gliders and screw-shaped aerial devices. Those ideas are often grouped together in popular accounts, but an ornithopter is specifically defined by flapping wings rather than rotating blades or a fixed wing.