Leonardo da Vinci’s aerial screw used a large spiral blade to suggest vertical flight.
In a drawing dated around 1489, Leonardo depicted a helical apparatus with a linen surface stretched over a lightweight frame. He reasoned that if the spiral rotated rapidly enough, it could screw itself upward through the air. The idea is commonly described as an early helicopter concept, although the sketch does not provide a workable engine or a complete mechanical solution.
The aerial screw differs from Leonardo’s flapping-wing ornithopter. The ornithopter imitates a bird’s wings, while the aerial screw uses rotary motion. That distinction makes the aerial screw especially relevant to the later history of helicopters.
Modern rotorcraft use powered rotors and aerodynamic blades rather than Leonardo’s continuous spiral surface. Engineers and historians therefore treat the design as an important conceptual predecessor, not as a functioning helicopter. Its value was identifying vertical lift as a separate challenge from gliding or forward flight.