Leonardo da Vinci’s aerial screw is often regarded as an early forerunner of the helicopter.
Drawn around 1489, the aerial screw features a helical sail wrapped around a central shaft. Leonardo reasoned that turning the shaft would make the spiral press against the air and lift the machine, much as a screw advances through a solid material.
The concept resembles a helicopter because it uses a rotating lifting surface rather than fixed wings. However, Leonardo’s machine was not a working helicopter: its proposed linen-covered helical surface and human-powered mechanism could not provide enough lift with the technology of the time.
Modern helicopters use powered rotors, aerodynamic blades, and control systems that Leonardo’s sketch did not include. The aerial screw is therefore best understood as a visionary mechanical concept, not a completed aircraft.