Leonardo da Vinci sketched an aerial screw as a conical machine intended to rise vertically by turning a helical surface.
The drawing appears in Leonardo’s notes from around 1489 and is often described as an early helicopter concept. It shows a large spiral structure supported by a frame, with a proposed mechanism for making the screw rotate. Leonardo reasoned that the helical surface could “screw” through the air in a way resembling a screw moving through a solid material.
The design was not a working helicopter. Its proposed power source and structure could not provide practical lift, and the machine was never tested successfully. Modern helicopters use powered rotors rather than a fabric-covered spiral. The aerial screw is nevertheless historically important because it demonstrates Leonardo’s attempt to apply mechanical principles to vertical flight, centuries before powered rotorcraft became possible.