Leonardo da Vinci’s ornithopter was a flying-machine design based on the flapping motion of birds.
Leonardo studied bird anatomy, wing movement, and the mechanics of flight in notebooks produced mainly during the late fifteenth and early sixteenth centuries. His ornithopter drawings show a human pilot operating large wings through mechanical linkages, often with the pilot lying prone or standing within a frame.
The concept was not successful as a practical aircraft. Human muscles cannot supply enough power to lift a person with flapping wings of the proposed scale, and the machine lacked a suitable lightweight power source. Leonardo nevertheless recognized that flight required careful attention to lift, balance, and control.
An ornithopter differs from an aerial screw because it generates lift through flapping wings rather than rotary motion. Modern experimental ornithopters do exist, but Leonardo’s designs were studies and proposals, not functioning aircraft.