Leonardo da Vinci's 1489 helical flying-machine design is known as the aerial screw.
The drawing shows a large spiral sail wrapped around a central shaft and supported by a circular frame. Leonardo proposed that the rotating screw might press against the air and lift the structure, an idea often compared with the principle of a modern helicopter rotor.
The aerial screw was a concept rather than a completed aircraft. The design lacked a practical power source and a sufficiently light structure, so Leonardo never demonstrated powered flight with it. Its importance lies in treating vertical lift as a mechanical problem rather than relying only on wings or gliding.
The aerial screw is sometimes casually called a helicopter, but that wording can be misleading. The first successful powered helicopters appeared in the twentieth century, more than four centuries after Leonardo's sketch. Historians generally describe his machine as a helicopter precursor or conceptual ancestor.