Birds inspired the wing movement in Leonardo da Vinci’s ornithopter designs.
An ornithopter is a machine intended to fly by flapping wings rather than by using fixed wings or a propeller. Leonardo studied birds in flight and filled notebooks with observations about wing shapes, balance, air currents, and the mechanics of flapping.
His designs attempted to translate biological motion into a human-powered machine. Some included a pilot lying or standing inside a framework and operating wings through pedals, levers, and other mechanical linkages. Leonardo understood that flight depended on both lift and control, but human muscles alone could not provide enough power for a practical flapping aircraft of his designs.
Leonardo also examined bats and other flying creatures, and not every flying-machine sketch was strictly bird-based. However, birds were the principal natural model behind his ornithopter concept. Modern ornithopters have flown, but they use improved materials, motors, and control systems.