Leonardo da Vinci's aerial screw used a pyramid-shaped helical blade to suggest powered flight.
Leonardo sketched the aerial screw in the 1480s, probably around 1489. The drawing shows a large spiral surface wrapped around a central mast. His notes suggest that if the screw were rapidly rotated, its helical shape might press against the air and lift the machine upward.
The concept resembles a helicopter rotor in its broad aim, but it could not have flown as drawn. The proposed materials and human power source would not have produced enough lift, and the design lacked a practical system for controlling flight. It was an important example of Leonardo treating air as a medium that machines could push against.
The aerial screw is sometimes called a helicopter prototype, but that label can mislead. Modern helicopters use powered rotors, aerodynamic blades, and control systems that are fundamentally more developed than Leonardo's paper design.