Leonardo da Vinci’s proposed flying machine with a helical rotor was called the aerial screw.
Leonardo sketched the aerial screw around 1489. Its design used a large, spiral-shaped linen sail stretched over a lightweight frame. He imagined the spiral rotating rapidly so that it would “screw” upward through the air, much as a screw moves through a material.
The aerial screw is often described as an early ancestor of the modern helicopter, but it was not a working helicopter. Leonardo’s drawing did not provide a practical engine or a complete method for producing enough power. Human muscle alone could not have turned the large rotor fast enough to lift the structure.
The concept is still historically important because it shows Leonardo thinking about vertical flight centuries before powered helicopters became possible. It is also commonly confused with the ornithopter, another Leonardo design that attempted flight through flapping wings rather than a rotating spiral.