Leonardo da Vinci sketched an aerial screw using a helical sail as a rotary-wing aircraft concept.
The drawing, usually dated to around 1489, shows a large spiral surface wrapped around a central mast. Leonardo reasoned that if the spiral could be forced to rotate rapidly, it might screw upward through the air in a way similar to a screw entering a material. The sketch is one of his best-known studies of vertical flight.
The design did not use a modern helicopter rotor. Its broad helical surface would have been heavy and difficult to turn, and the human power available in the Renaissance was not sufficient for practical flight. Leonardo’s notes did not establish a complete working propulsion system for it.
The aerial screw is often called a helicopter ancestor, but that is a historical comparison rather than a claim that Leonardo built a helicopter. The modern helicopter relies on rotating blades that generate lift through aerodynamic airfoils. Leonardo’s concept remains significant because it clearly imagined vertical lift through rotary motion centuries before powered helicopters became practical.