Leonardo da Vinci’s 1489 helical rotor design intended to rise into the air is commonly called the aerial screw.
The drawing shows a large spiral structure made from reeds, linen, and wire, with a central mast and a platform. Leonardo reasoned that rotating the spiral could “screw” itself upward through the air, much as a screw advances through wood. The design is one of his best-known studies of vertical flight.
The aerial screw was not a helicopter in the modern engineering sense. It had no practical power source capable of turning its large rotor, and its materials and aerodynamic assumptions were insufficient for sustained flight. It is better understood as an early conceptual ancestor of the helicopter.
Leonardo’s notes on the design are associated with the period around 1489. Modern replicas are usually demonstrations of the idea rather than direct evidence that the original could fly.