What was Leonardo da Vinci’s spiral flying-machine design called?

Leonardo da Vinci’s spiral flying-machine design was called the aerial screw.

Leonardo drew the aerial screw in a notebook entry usually dated to about 1489. The design shows a large helical surface mounted around a central shaft. His idea was that rapidly turning the screw would press against the air and raise the machine, a concept sometimes compared with a modern helicopter rotor.

The aerial screw was a conceptual design, not a tested aircraft. Leonardo did not have a lightweight engine capable of driving such a large rotor, and the materials available in the 15th century would have made the structure difficult to build. The sketch also does not provide a complete practical solution for stability or control.

The aerial screw is often described as a helicopter precursor, but it was not a helicopter in the modern engineering sense. A helicopter uses powered rotors and carefully designed aerodynamic control systems. Leonardo’s invention is important mainly as an early attempt to apply a screw-like lifting mechanism to flight.