Leonardo da Vinci’s spiral machine intended to rise through the air is called the aerial screw. It used a large helical sail wrapped around a central frame, creating a form that resembles a giant screw.
Leonardo drew the aerial screw around 1489 in a manuscript associated with his studies of flight. His notes suggested that if the helical surface were turned rapidly, it could push against the air and lift the machine. The proposed craft would have required several people to operate mechanisms inside the frame.
The aerial screw is often described as a precursor to the helicopter, but it was not a helicopter and was never tested as a practical aircraft in Leonardo’s era. Its structure lacked a modern powered rotor and suitable lightweight materials. The significance of the design lies in Leonardo’s attempt to reason about vertical flight through the interaction of a rotating surface and air.