Leonardo da Vinci’s aerial screw used a helical blade to suggest vertical lift from a rotating flying machine.
Drawn around 1489, the device resembles a large screw with a helical surface wrapped around a central mast. Leonardo proposed that if the screw rotated rapidly, its surface could push against the air and raise the structure, an idea often described as an early helicopter concept.
The drawing is important in the history of flight, but it was not a working helicopter. Leonardo did not have an engine light and powerful enough to rotate the large rotor, and the proposed structure would also have faced stability and aerodynamic problems.
The aerial screw is often confused with Leonardo’s ornithopter. The ornithopter depends on flapping wings; the aerial screw depends on rotary motion. Modern helicopters use rotating airfoils and powered rotors, so the resemblance is conceptual rather than evidence that Leonardo built a helicopter.