Leonardo da Vinci’s 1489 rotating machine with a helical sail was intended to resemble a helicopter.
His aerial-screw drawing depicts a large spiral surface mounted on a central shaft. Leonardo reasoned that if the screw were turned quickly enough, its helical shape would bite into the air and lift the structure. The idea resembles the operating principle of a helicopter rotor, although it is not a helicopter in the modern engineering sense.
The machine could not have flown as drawn because human muscles and Renaissance materials could not provide enough power for the proposed structure. It also lacked a practical system for controlling flight. The design is therefore best understood as an early conceptual ancestor of vertical-flight machines, not as the first working helicopter. “Aerial screw” is the specific name commonly used for Leonardo’s invention.