Leonardo da Vinci designed the aerial screw as a machine intended to lift into the air using a helical linen sail.
Leonardo drew the design around 1489 in one of his notebooks. The device has a large, spiral-shaped surface stretched around a framework. He reasoned that rotating this screw would make it climb, much as a screw moves through a solid material.
The aerial screw is often called a helicopter ancestor, but it was not a working helicopter. Its materials, power source, and human strength would not have produced enough lift. Modern helicopters use powered rotors that generate lift through aerodynamic blades, a principle different from Leonardo’s proposed rotating spiral.
The sketch is historically important because it shows Leonardo thinking about vertical flight centuries before powered aircraft existed. It should also be distinguished from his ornithopter, which was based on flapping wings rather than a rotating screw.