Leonardo da Vinci’s screw-shaped flying-machine concept was the aerial screw.
Leonardo sketched the aerial screw around 1489. The design featured a helical surface made from reed, linen, and wire, supported by a circular frame. Leonardo theorized that turning the screw rapidly could make it rise by pressing against the air, much as a screw moves through a solid material.
The aerial screw is frequently called a helicopter ancestor, but it was not a helicopter and could not fly as drawn. It lacked a practical powered engine, and the proposed human-powered mechanism would not have produced enough lift. Its importance lies in the early recognition of the aerodynamic potential of a rotating screw.
The idea is also distinct from Leonardo’s ornithopter, which attempted flight through flapping wings. The aerial screw used rotational motion rather than imitation of bird flight.