Leonardo da Vinci’s aerial screw used a helical blade to imitate the lifting action of a screw in air.
Leonardo drew the design in a manuscript usually dated to about 1489. The machine had a large spiral surface wrapped around a central mast, with a platform and supports beneath it. He proposed that people could turn the mechanism and force the spiral through the air.
The idea is often described as an early helicopter concept, but that comparison needs care. Leonardo’s drawing does not provide a modern engine, and the materials and human power available in the fifteenth century could not have produced enough lift for flight.
The design was nevertheless historically important because it treated flight as an engineering problem involving air and a rotating lifting surface. Modern helicopters use powered rotors rather than a single linen-covered screw.