Leonardo da Vinci called his helical flying-machine design the aerial screw.
Leonardo sketched the aerial screw around 1489. The design shows a large helical surface, probably made from linen sealed with starch, mounted on a framework. He reasoned that turning the screw would make it rise by “screwing” into the air, much as a screw moves through wood.
The aerial screw is often described as an early helicopter concept, but it was not a working helicopter. Leonardo did not build a full-scale machine, and the materials and human power available in Renaissance Italy could not have produced enough lift for the proposed structure. Modern reconstructions generally treat it as an imaginative experiment rather than a practical aircraft.
The design is also sometimes confused with Leonardo’s ornithopter studies, which attempted to imitate flapping bird wings. The aerial screw instead used rotary motion and a helical lifting surface, making it one of the clearest early ancestors of rotorcraft.