Leonardo da Vinci modeled an ornithopter concept on the wingbeats of birds and bats.
An ornithopter is a machine intended to fly by flapping wings. Leonardo studied bird anatomy, wing movement, balance, and air resistance while developing several flying-machine sketches. His designs generally placed a human operator inside a frame who would power or control the wings through pedals, levers, or other mechanical linkages.
Leonardo understood that human muscles alone were unlikely to provide enough power for sustained flapping flight. Even so, his notebooks contain important observations about airflow, gliding, and the structure of natural wings. Those studies helped connect artistic observation with mechanical design, though they did not produce a proven man-powered aircraft.
An ornithopter is different from a helicopter, whose rotor spins, and from a glider, whose wings remain fixed while it descends or rides air currents. Leonardo also explored devices resembling a helicopter and parachute, but the birdlike flapping-wing category is specifically the ornithopter.