Leonardo da Vinci proposed an aerial screw, a rotating helical device intended to lift a machine from the ground.
His famous sketch shows a large spiral sail wrapped around a central mast. The concept was based on the idea that rotating the helical surface would force air downward and push the structure upward. In modern language, the design is often compared visually with a helicopter rotor, although it would not have worked as drawn with the materials and power available in Renaissance Italy.
Leonardo recorded the design around 1489. The drawing is an important example of his interest in translating natural and mechanical motion into engineering devices. It was a conceptual machine rather than a demonstrated aircraft, and no evidence shows that Leonardo built or tested a full-scale aerial screw.
The aerial screw should not be confused with the later helicopter. Modern helicopters use powered rotors with carefully shaped blades and controllable pitch. Leonardo’s proposal anticipated the general idea of rotary lift, but it did not provide the practical aerodynamics or engine needed for sustained flight.