Leonardo da Vinci sketched an aerial screw as a spiral-powered machine intended to rise through the air.
The design appears in the Codex Atlanticus, a large collection of Leonardo’s drawings and notes. It features a helical surface wrapped around a central mast. Leonardo reasoned that if the screw were spun rapidly, its spiral surface might push against the air and lift the structure.
The aerial screw is frequently described as a conceptual ancestor of the helicopter, but it was not a working helicopter. Leonardo did not have a lightweight engine capable of providing the necessary continuous power, and the drawing does not show a complete practical control system.
The idea also differs from his ornithopter, which uses flapping wings, and from a parachute, which slows a fall. Its historical importance lies in anticipating rotary-wing flight centuries before powered helicopters became feasible.