Leonardo da Vinci sketched an aerial screw with a helical surface intended to lift a machine into the air.
His drawing, usually dated to around 1489, shows a large spiral framework resembling a screw or modern helicopter rotor viewed in a vertical arrangement. Leonardo reasoned that if the helical surface rotated rapidly, it could “screw” upward through the air. The proposal is one of his best-known studies of powered flight.
The machine was never built as a practical aircraft. Renaissance materials and available power sources could not provide the combination of light weight, structural strength, and thrust needed for flight. The design also lacks the modern helicopter’s separate rotor, engine, and control systems.
The aerial screw is often called a helicopter in popular accounts, but that is a modern comparison rather than Leonardo’s own term. Its importance is conceptual: it explored vertical lift rather than relying on wings and forward motion. The sketch is therefore related to, but distinct from, Leonardo’s flapping-wing aircraft studies.