Leonardo da Vinci sketched an aerial screw as a large spiral aircraft concept designed to rise through the air.
Leonardo drew the aerial screw in the Codex Atlanticus around 1489. The design showed a helical sail or screw supported by a lightweight framework. Leonardo reasoned that turning the screw could make it “screw” upward through the air, an idea that resembles the principle behind later rotary-wing aircraft.
The aerial screw was not a working helicopter. Its proposed materials, scale, and human-powered mechanism would not have provided enough lift. Modern helicopters use rotating blades that generate aerodynamic lift rather than a fabric-covered spiral surface. The sketch is nevertheless frequently cited as an early conceptual ancestor of helicopter design, alongside Leonardo’s separate studies of flapping-wing machines.