Leonardo da Vinci’s aerial screw used a helical screw to rise vertically through the air.
Leonardo drew the design around 1489, during his investigations of flight. The sketch shows a large spiral surface made from linen and reeds, supported by a circular frame. He reasoned that turning the screw rapidly would force air downward and lift the structure upward.
The aerial screw is often called an early helicopter concept, but it was not a practical helicopter. Leonardo did not build a working full-size machine, and the design lacked a powered engine and a lightweight rotor system. Modern reconstructions generally treat it as an important conceptual ancestor rather than a successful aircraft.
The idea also differs from Leonardo’s ornithopter studies. An ornithopter would fly by flapping wings, while the aerial screw depends on rotary lift. Its historical importance lies in identifying vertical flight as a separate engineering problem centuries before powered helicopters became possible.