Leonardo da Vinci designed an aerial screw as a helicopter-like flying machine.
Leonardo drew the aerial screw around 1489–1490 in the manuscript known as the Codex Atlanticus. His design showed a helical linen sail stretched over a lightweight reed framework. He reasoned that turning the screw could make it rise by “screwing” through the air, much as a screw advances through a solid material.
The aerial screw was never built and tested by Leonardo, so it was not a working helicopter. Its proposed lifting principle also differed from the powered rotors used by modern helicopters. Leonardo’s sketch did not include an engine capable of supplying the necessary continuous rotation.
The design is often described as an early helicopter concept, but that label can be misleading. It was primarily a theoretical machine based on a rotating helix, and its historical importance lies in imagining vertical flight centuries before practical helicopters appeared.