Leonardo da Vinci’s aerial screw was a lifting-machine concept with a helical rotor intended to rise through the air when turned by people.
Leonardo drew the design around 1489. It used a large spiral surface made from reeds, linen, and wire, supported by a wooden framework. His notes suggested that the spiral might screw itself upward through the air, an idea that gives the concept its name.
The aerial screw was not a helicopter in the modern engineering sense. It had no engine, and the human-powered mechanism would not have supplied enough energy for sustained flight. The design also lacked the control systems and lightweight materials needed for practical vertical flight.
Even so, the sketch is frequently discussed as an early conceptual ancestor of the helicopter. Modern helicopters use powered rotors that generate lift by accelerating air downward, rather than a rigid linen spiral moving like a screw.