Leonardo da Vinci’s aerial screw was a flying-machine design based on the rotating motion of a screw.
Leonardo drew the aerial screw around 1489 in a manuscript now associated with the Codex Atlanticus. The machine features a large helical surface made from reed, linen, and wire, mounted around a central shaft. Leonardo reasoned that turning the screw could force air downward and lift the structure upward.
The design is frequently described as a predecessor of the modern helicopter, but it was not a working helicopter. It lacked a practical engine and a clear mechanism capable of producing enough sustained power. Its rotating spiral also differs substantially from the powered rotor blades used by helicopters.
The aerial screw is sometimes called Leonardo’s helicopter because of its appearance and vertical-flight idea. That label is useful as shorthand but can mislead readers about its engineering maturity. The drawing is best understood as a conceptual investigation into vertical lift, made centuries before engines and rotorcraft technology became available.