What did Leonardo da Vinci call his 1480s spiral machine intended to lift air?

Leonardo da Vinci called his 1480s spiral machine intended to lift air an aerial screw.

Leonardo’s aerial screw was a large helical rotor supported by a frame. His notes proposed that the rotating screw could press against the air and rise, an idea often described as an early helicopter concept. The machine was intended to be turned by people operating inside the structure, although the human power available would almost certainly have been insufficient for sustained flight.

The design was drawn in Leonardo’s notebooks, including material associated with the Codex Atlanticus. It was not built and tested in Renaissance Italy, and the historical evidence does not show that Leonardo made a successful flying machine. The famous drawing is therefore an example of inventive aerodynamic speculation rather than a working aircraft.

The aerial screw is sometimes casually called Leonardo’s helicopter. That label is useful as a comparison, but it can mislead: modern helicopters use powered rotors, control systems, and lightweight materials that were unavailable to Leonardo. The design’s lasting importance is its clear attempt to use a rotating helical surface for vertical lift.