Leonardo da Vinci’s screw-shaped rotor concept for flight is called the aerial screw.
Leonardo drew the aerial screw around 1489, describing a device with a helical surface intended to “screw” upward through the air. The design is often compared with a modern helicopter because it uses a rotating screw-like lifting principle. Its frame was shown as a large structure covered with a material such as reeds and cloth.
The aerial screw was not a functioning helicopter. It lacked a practical engine, suitable lightweight materials, and the aerodynamic understanding needed for controlled powered flight. Modern helicopter rotors also work differently: they use airfoil-shaped blades rotating around a hub rather than a continuous helical surface.
The concept remains historically significant because it shows Leonardo reasoning from the behavior of screws and fluids toward vertical flight. It should not be confused with Leonardo’s flapping-wing ornithopters, which sought lift through repeated wing beats rather than rotation.