Leonardo da Vinci’s 1489 rotating-wing concept is called the aerial screw.
Leonardo described a helical linen sail stretched over a light framework. He reasoned that if the screw rotated rapidly enough, its surface would bite into the air and lift the machine. The drawing resembles a large vertical screw, not a modern helicopter rotor.
The design was probably impractical because a human-powered mechanism could not generate enough lift. Leonardo did not build a working aerial screw, and the sketch contains no complete engine or control system.
The aerial screw is often described as a helicopter ancestor, but that wording can mislead. Modern helicopters use powered rotors and aerodynamic blades; Leonardo’s proposal was a theoretical experiment in air resistance and vertical flight.