Leonardo da Vinci called his screw-shaped aircraft design intended to rise vertically the aerial screw.
Leonardo sketched the aerial screw around 1489–1490 in the Codex Atlanticus. The design used a large helical surface made from reed, linen, and wire. His notes suggested that if the screw were spun rapidly, it might push against the air and lift the machine.
The aerial screw is often described as an early helicopter concept, but it was not a working helicopter. Leonardo did not provide a practical engine or a lightweight power system capable of turning the rotor fast enough. The proposed machine also had serious problems involving weight, stability, and the behavior of its fabric surface.
The design is distinct from Leonardo’s ornithopter, which copied the flapping motion of birds. The aerial screw instead anticipated the rotating-wing principle used by helicopters centuries later. Its importance lies chiefly in recognizing that vertical flight might be achieved with a rotating helical rotor.