Leonardo da Vinci sketched an aerial screw as a possible vertical-flight machine.
His design, drawn around 1489, used a large helical surface intended to rotate around a central mast. Leonardo reasoned that the rotating screw might bite into the air much as a screw moves through a solid material. The device was never built by Leonardo and could not have flown with the materials and power sources available in Renaissance Europe.
The aerial screw is often described as an early ancestor of the modern helicopter, but it was not a working helicopter. Modern helicopters use powered rotors, aerodynamic blades, and controlled lift; Leonardo’s sketch provided a striking mechanical analogy rather than a tested aircraft.
The design is also sometimes called Leonardo’s helicopter. That label is retrospective: the word “helicopter” and practical helicopter engineering belong to much later periods.