Leonardo da Vinci called his screw-shaped flying machine the aerial screw.
He sketched the design around 1489 or 1490. The drawing shows a large helical surface wrapped around a central mast. Leonardo reasoned that if the screw-like surface were turned rapidly, it might push against the air and lift the machine upward.
The aerial screw is frequently labeled a helicopter ancestor because its proposed vertical-lift principle resembles that of a rotorcraft. It was not a helicopter in the modern engineering sense: the design lacked an engine, a practical rotor system, and a method for controlling torque. Four people were shown operating the mechanism.
The concept’s importance is chiefly historical. It demonstrates Leonardo’s attempt to treat air as a medium that could be mechanically engaged, much as a screw engages water or wood. Modern helicopters use rotating blades rather than a continuous helical sail.