Leonardo da Vinci’s 1489 rotary-wing concept was the aerial screw.
Leonardo drew the aerial screw in the Codex Atlanticus, probably around 1489. His design showed a large helical surface made from linen stiffened with reeds. He reasoned that turning the spiral surface rapidly could make it “screw” upward through the air, much as a screw moves through a solid material.
The aerial screw was not a working helicopter. Leonardo did not provide a practical engine, a sufficiently light frame, or a tested method for producing the required rotation. Modern historians therefore describe it as an imaginative precursor to rotary-wing flight rather than the first helicopter.
It is often confused with Leonardo’s later ornithopter studies, which attempted to imitate the flapping motion of birds. The aerial screw instead used a rotating helical surface, making it conceptually closer to a helicopter rotor than to a bird-like aircraft.