Leonardo da Vinci’s helical flying-machine design was called the aerial screw.
Leonardo sketched the aerial screw around 1489–1490 in a manuscript now associated with the Codex Atlanticus. The machine had a large spiral surface, or screw, intended to push against the air as it rotated. Its appearance resembles a modern helicopter rotor, which is why it is often described as an early helicopter concept.
The design was not a functioning helicopter. Leonardo did not have a practical lightweight engine or a proven way to rotate the screw rapidly enough for human flight. The sketch therefore represents an important aerodynamic idea rather than a demonstrated aircraft.
A common mix-up is calling the aerial screw the first helicopter. Modern helicopters use powered rotors that generate lift through rotating airfoils, while Leonardo’s proposal depended on a linen-covered helical structure. Its historical importance lies in showing that vertical flight had been imagined centuries before powered helicopters became possible.