What was Leonardo da Vinci’s 1489 flying-machine design called the aerial screw?

Leonardo da Vinci’s 1489 aerial screw is regarded as a helicopter precursor.

Leonardo sketched the aerial screw in a notebook, showing a large helical rotor made from reeds, linen, and wire. His notes proposed that turning the screw could make it rise by pushing against the air. The design was not a working helicopter, because the available materials and human power could not provide enough lift.

The aerial screw is often described as an early helicopter concept because its central idea is vertical flight using a rotating rotor. It should not be confused with an airplane or glider, which rely mainly on forward motion and fixed wings to generate lift.

Modern helicopters use powered rotors, aerodynamic blades, and engines or electric motors. Leonardo’s sketch lacked those technologies, but it demonstrated an important attempt to reason about flight mechanically rather than imitate bird wings alone.