What ancient machine did Leonardo da Vinci adapt into an aerial screw?

Leonardo da Vinci adapted the idea of a screw pump into an aerial screw.

His famous aerial-screw drawing dates from around 1489. The device has a helical surface wrapped around a vertical frame, with a platform and mast beneath it. Leonardo reasoned that if the screw turned rapidly, its surface might push against the air and lift the machine.

The concept is often called a helicopter precursor, but it was not a working helicopter. Leonardo did not have a lightweight engine capable of turning the large rotor quickly enough, and the design lacked several features needed for controlled flight. The analogy with a screw pump comes from the way a rotating helix can move a fluid—in this case, Leonardo imagined the screw gripping air.

The aerial screw influenced later popular ideas about vertical flight, though modern helicopters use rotating blades that generate lift in a very different engineered arrangement. Leonardo’s sketch is therefore best understood as an early conceptual study of vertical flight, not as the invention of a practical helicopter.