Leonardo da Vinci designed an aerial screw with a spiral surface intended to lift itself into the air.
The drawing, usually dated to about 1489, shows a large helical structure supported by a framework. Leonardo reasoned that if the screw rotated rapidly, its spiral surface might press against the air and produce upward motion. The concept is often described as an early helicopter ancestor, but it was not a working helicopter and had no practical engine capable of supplying the required power.
Leonardo’s aerial screw was based on the same broad idea as a screw propeller: rotation could create thrust. Modern helicopters use rotor blades shaped and powered to generate lift, while Leonardo’s continuous spiral would be too heavy and inefficient at the proposed scale. The sketch remains significant as a clear Renaissance study of vertical flight.