Leonardo da Vinci sketched an aerial screw, a machine with a large spiral intended to lift itself through the air.
The drawing appears in Leonardo's Codex Atlanticus and is usually dated to around 1489. It shows a helical surface wrapped around a central mast, with a platform and people turning bars to rotate the mechanism. Leonardo reasoned that the spiral might screw into the air in the same way that a screw moves through a solid material.
The aerial screw is often described as an early helicopter, but that label can mislead. The sketch does not show a modern engine, lightweight materials, or a practical control system, and its proposed power source would not have been sufficient for real flight. It was a conceptual study rather than a demonstrated aircraft.
The idea nevertheless anticipated the visual principle of a rotating rotor. Its significance lies in Leonardo's attempt to apply a familiar mechanical form—the screw—to the problem of vertical lift.