Leonardo da Vinci designed an aerial screw as an early helicopter concept.
His famous drawing, usually dated to around 1489, shows a large helical sail wrapped around a central mast. Leonardo reasoned that rotating the screw could make the sail bite into the air and lift the machine. The design is sometimes called the “helical air screw.”
The machine was never built or flown by Leonardo, and it lacked a practical engine, lightweight materials, and a workable method for controlling rotation. Its importance is conceptual: it shows Leonardo trying to apply the principle of a screw moving through a fluid to flight. Modern helicopters do not operate by simply reproducing his large spiral sail.
The aerial screw is also commonly mistaken for the ornithopter designs in Leonardo’s notebooks. An ornithopter seeks lift through flapping wings, while the aerial screw uses rotary motion. Both belong to Leonardo’s investigations of human flight, but they represent different mechanical ideas.