What was Leonardo da Vinci’s proposed rotating aerial device commonly called?

Leonardo da Vinci’s proposed rotating aerial device is commonly called the aerial screw. He drew it around 1489, imagining a large helical structure that would rise if its screw-like surface pushed against the air.

The drawing resembles a giant spiral or auger mounted on a frame. Leonardo suggested that a crew could turn the structure using mechanisms, but the design could not have lifted itself with the materials and power sources available in the Renaissance. It is therefore considered an early conceptual ancestor of the helicopter, not a working helicopter.

The aerial screw is often described as a helicopter precursor because both ideas use rotating aerodynamic surfaces to produce upward force. However, modern helicopters rely on powered rotor blades, while Leonardo’s concept used a continuous helical surface. The idea illustrates Leonardo’s habit of adapting mechanical principles from screws, mills, and other machines to unexplored problems.