Leonardo da Vinci’s aerial screw is commonly regarded as an early helicopter design.
Leonardo drew the aerial screw in the 1480s, probably in the Codex Atlanticus. The machine featured a large helical rotor made from reeds, linen, and wire. Leonardo reasoned that if the screw could be turned rapidly, its spiral surface might press against the air and lift the machine.
The design was never built by Leonardo and would not have flown as drawn. Its proposed rotor was too large and heavy for the available human power, and the machine lacked a practical way to generate sustained rotation. Even so, the sketch is an important early example of thinking about vertical flight.
The aerial screw is often called a helicopter prototype, but it was not a working helicopter. Modern helicopters depend on powered rotors, aerodynamic blades, and control systems developed centuries later. Leonardo’s concept is better understood as a visionary precursor to rotary-wing aircraft.