Leonardo da Vinci’s aerial screw used a large rotating screw to imitate the lifting action of a helicopter rotor.
Leonardo sketched the aerial screw in the 1480s, probably in a notebook now associated with his studies of flight. The design shows a helical sail made from linen, held on a framework and intended to rotate around a central axis. Leonardo reasoned that the screw could push against the air and rise.
The aerial screw was not a working helicopter. Its proposed materials and human-powered mechanism could not provide enough sustained lift, and no evidence shows that Leonardo built or flew a full-size version. It is nevertheless often described as a conceptual ancestor of the helicopter.
It should not be confused with Leonardo’s ornithopter, which sought flight through flapping wings. The aerial screw relied on rotary motion, making it a separate idea in Leonardo’s extensive studies of mechanical flight.