What did Leonardo da Vinci call his rotating flying-machine design?

Leonardo da Vinci called his rotating flying-machine design an aerial screw.

Drawn around 1489, the aerial screw is a large helical structure intended to rise by rotating through the air. Leonardo’s notes describe a framework covered with reed, linen, and wire. The machine is often compared with a modern helicopter rotor because both concepts rely on rotating surfaces to generate lift.

The design was probably inspired partly by the Chinese flying top, a toy known in Europe through trade and illustrations. Leonardo’s sketch is not a complete engineering plan, and the proposed machine would have been extremely heavy for its available power. No evidence shows that Leonardo built or flew it.

The aerial screw is sometimes incorrectly called the world’s first helicopter. It was an early rotorcraft concept, but practical helicopters required lightweight engines, efficient rotors, and stable control systems that did not exist in Renaissance Italy.