What rotating flying-machine concept did Leonardo da Vinci draw around 1489?

Leonardo da Vinci drew an aerial screw, a rotating flying-machine concept, around 1489.

The design appears in Leonardo’s notebooks as a large helical structure intended to rise through the air when rotated. Its shape resembles a screw or a modern rotor blade arranged around a central shaft, which is why historians often discuss it as an early conceptual ancestor of the helicopter.

The aerial screw was not a helicopter in the modern engineering sense. Leonardo did not provide a workable engine, and the proposed materials and human power would not have produced enough thrust for sustained flight. The design was a speculative study rather than a tested aircraft.

It is also sometimes incorrectly called the first helicopter. A helicopter uses powered rotors with carefully designed blades and control systems; Leonardo’s sketch anticipated the general idea of rotary lift but did not create a functioning rotorcraft.