Leonardo da Vinci sketched an aerial screw with a large helical sail intended to lift a machine into the air.
Leonardo drew the design around 1489, showing a frame supporting a spiral surface made from reeds, linen, and wire. His notes suggest that turning the screw would force air downward and make the device rise. The concept is therefore often compared with a helicopter rotor, although it could not operate as a practical powered aircraft.
The aerial screw was not built or flown in Leonardo's lifetime. Its proposed mechanism also lacked a suitable engine and a lightweight structure. Modern replicas are usually experimental interpretations rather than exact historical reproductions.
The design is sometimes incorrectly called Leonardo's helicopter. That name is a modern comparison: the aerial screw was not a helicopter in the technical sense, because it had no powered rotor system capable of sustained controlled flight. It remains one of his best-known studies of vertical flight.