What rotary-wing aircraft precursor did Leonardo da Vinci sketch in 1489?

Leonardo da Vinci sketched an aerial screw in 1489 as a rotary-wing aircraft precursor.

His design showed a large helical sail made from reed, linen, and wire. Leonardo reasoned that turning the screw would make it “screw” upward through the air, much as a threaded screw moves through a material. The drawing is among his best-known studies of vertical flight.

The aerial screw was a concept, not a working helicopter. The materials, power source, and human strength available in Renaissance Italy could not have produced enough lift for a practical machine. It is also different from Leonardo’s ornithopter, which used flapping wings inspired by birds and bats.

Modern helicopters use rotating blades and powered engines, so they share the aerial screw’s broad rotary-lift idea but not its exact construction. The design is often described as an early helicopter concept rather than the first helicopter itself.