Leonardo da Vinci’s aerial screw was a helical-rotor aircraft concept intended to rise vertically through the air.
He drew the design in a notebook dated around 1489. The machine featured a large spiral surface wrapped around a central shaft, resembling a giant screw. Leonardo reasoned that rotating the structure could drive it upward by pressing against the air.
The aerial screw is often described as an early ancestor of the helicopter, but it was not a working helicopter. The original concept lacked a practical engine and had no demonstrated means of producing enough lift. Modern helicopters use powered rotors with carefully shaped blades rather than a single continuous screw surface.