Leonardo da Vinci designed an aerial screw with rotating blades like a giant screw.
He drew the machine around 1489–1490, probably in a notebook now associated with the Manuscript B of the Institut de France. The design consisted of a helical linen surface stretched over a light framework. Leonardo reasoned that turning the screw could push against the air and lift the machine upward.
The aerial screw is often described as a conceptual ancestor of the helicopter, but it was not a working helicopter. It had no engine, and the materials and power available in the fifteenth century could not have made it fly as drawn. Modern replicas have demonstrated the visual idea, but not a practical Renaissance aircraft.
The word “screw” refers to the machine's helical shape, not to a conventional propeller. Leonardo also studied wings, gliding, and flapping flight, so the aerial screw was one part of a much larger investigation into aviation.