What did Leonardo da Vinci’s aerial screw use to imitate for lift?

Leonardo da Vinci’s aerial screw used a helical screw to imitate the lifting action of a screw moving through a solid material.

Leonardo drew the design around 1489. The machine had a large spiral surface wrapped around a central mast. He reasoned that if the helical surface were rapidly rotated, it might press against air and rise. The idea resembles a very large vertical propeller, although the proposed materials and human power were not sufficient for practical flight.

The aerial screw is often described as a helicopter ancestor, but it was not a working helicopter. Modern helicopters use rotating airfoils, engines, and carefully engineered rotors. Leonardo’s sketch lacks the power and aerodynamic design needed for controlled takeoff and sustained flight.

Its historical importance is conceptual. It shows Leonardo exploring vertical flight centuries before powered helicopters became possible. The name “aerial screw” comes from the screw-shaped lifting device, not from a conventional screw used to fasten parts.