Leonardo da Vinci’s rotating-wing machine is known as the aerial screw.
Leonardo sketched the aerial screw around 1489. The design shows a large helical surface made from reeds, linen, and wire, mounted on a frame. Leonardo suggested that turning the structure could make it rise by “screwing” through the air, an idea that resembles the principle of a helicopter rotor.
The machine could not have flown as drawn because its human operators could not generate enough power, and the materials and control systems were inadequate. Even so, the sketch is a famous early exploration of vertical flight. It should not be called a functioning helicopter, because helicopters require powered rotors, control mechanisms, and a workable airframe.
The aerial screw is sometimes described as a helicopter ancestor, but it was a conceptual design rather than a direct prototype of a modern aircraft.