What rotating aerial-machine concept did Leonardo da Vinci sketch in 1489?

Leonardo da Vinci’s rotating aerial-machine concept sketched in 1489 was the aerial screw.

Leonardo drew a large helical structure supported by a circular frame and proposed that it could rise if the screw were turned rapidly. His notes compared the principle to a screw moving through a solid substance. The design is often described as an early helicopter concept, although it lacked an engine and a practical lightweight rotor.

The drawing belongs to Leonardo’s wider investigation of flight. He also examined gliding, flapping wings and parachutes, testing ideas against observations of birds and air currents. The aerial screw was therefore part of a sequence of theoretical studies rather than a machine he built and flew.

A modern helicopter uses powered rotors that generate lift through rotating blades. Leonardo’s device would have required far more power than a human crew could provide, and its continuous helical surface would have been heavy. Its historical importance is the early recognition that rotation could produce vertical lift.