Leonardo da Vinci’s helical flying-machine concept is called the aerial screw.
Leonardo drew the aerial screw in a notebook dated approximately 1489. The design featured a large helical surface made from linen, with the structure supported by reeds. Leonardo reasoned that if the screw were rotated rapidly, it might rise by forcing air downward.
The idea is often called an early helicopter concept because it uses a rotating, screw-like lifting surface. However, it was not a helicopter in the modern engineering sense. Leonardo did not provide a practical engine or demonstrate that the machine could lift itself.
The aerial screw also differs from his ornithopter. An ornithopter imitates flapping wings, while the aerial screw depends on rotary motion. Modern helicopters use powered rotors with carefully shaped blades, technologies unavailable to Leonardo in Renaissance Italy.