Leonardo da Vinci’s rotating aerial-machine concept was called the aerial screw.
Leonardo drew the aerial screw around 1489. The design showed a large helical surface made from reeds, linen, and wire, supported by a circular frame. Leonardo reasoned that turning the screw could make it rise by pushing against the air, much as a screw advances through a solid material.
The concept is often described as a distant ancestor of the helicopter, but it was not a practical helicopter. It lacked a workable power source and a modern rotor system, and its proposed materials and dimensions would not have allowed a useful flight. The sketch is important mainly because it recognized that rotation could create lift.
The aerial screw should not be confused with Leonardo’s flapping-wing ornithopters. One relies on a helical rotating surface; the other imitates the wingbeat of a bird.