Leonardo da Vinci’s spiral aerial device is called the aerial screw.
Leonardo drew the design around 1489–1490 in the manuscript known as the Codex Atlanticus. It shows a large helical surface made from reeds, covered with linen, and stretched around a framework. Leonardo suggested that turning the screw could make it rise through the air, comparing its action with a screw moving into wood.
The aerial screw is often described as a helicopter ancestor, but it was not a working helicopter. Leonardo did not have a powered engine light enough to drive it, and the design’s weight and aerodynamic limitations would prevent a full-scale version from flying as drawn. Modern models are mainly demonstrations of the idea rather than reconstructions of a proven aircraft.
It is also different from Leonardo’s ornithopter, which used flapping wings. The aerial screw relied on rotating motion and is therefore especially important in the history of vertical-flight concepts.