Leonardo da Vinci sketched an aerial screw as a large rotating spiral intended to rise into the air.
The design appears in Leonardo’s notes from around 1489. It has a helical surface wrapped around a central framework, resembling a giant screw or modern auger. Leonardo reasoned that if the spiral moved rapidly enough, it could push against the air and lift the structure.
The aerial screw was not a working helicopter. Its proposed materials and human-powered mechanism could not have supplied enough lift, and no evidence shows that Leonardo built or tested a full-size version. The idea is nevertheless often described as an early conceptual ancestor of the helicopter.
Leonardo’s sketch is sometimes called a “helicopter,” but that modern label can mislead. The machine had one large rotor-like spiral rather than the powered rotor system used by modern helicopters.