Leonardo da Vinci called his rotating flight device an aerial screw in a sketch dated around 1489.
The aerial screw used a helical sail or screw-shaped surface intended to compress air and lift the structure upward when rotated. Leonardo’s drawing shows a large framework with a central mast and a spiral surface. The concept is often described as a distant ancestor of the modern helicopter, although it was not a helicopter in the engineering sense.
Leonardo did not build a proven full-scale working model, and the proposed mechanism lacked an effective modern engine and a practical way to control rotation. Its significance lies in recognizing that rotary motion might produce vertical lift, rather than relying only on flapping wings or gliding.
The design is frequently confused with Leonardo’s ornithopter sketches. An ornithopter imitates bird flight by flapping wings; the aerial screw instead uses a rotating spiral. That difference makes the aerial screw one of his most recognizable aviation concepts.