Leonardo da Vinci called his 1485 spiral-powered flying-machine design the aerial screw.
The drawing shows a large helical sail wrapped around a central mast. Leonardo reasoned that turning the structure rapidly could make the screw bite into the air and lift the machine, much as a screw moves through a solid material. The design was probably intended to be powered by people turning cranks, although no practical mechanism is shown that could provide enough energy.
The aerial screw is often described as a helicopter ancestor, but it was not a working helicopter. Leonardo had no lightweight engine, and the proposed frame and sail would have been far too heavy for human-powered flight. Its importance lies mainly in the clear use of a rotating lifting surface.
The concept predates powered helicopters by centuries. Modern helicopters use rotor blades, engines and aerodynamic control systems rather than a continuous spiral sail.