Leonardo da Vinci designed an aerial screw with a large helical rotor intended to rise through the air by human power.
He drew the machine around 1489 in a notebook usually associated with the Codex Atlanticus. The design resembles a giant screw or helical sail, with a framework supporting a linen-covered spiral surface.
Leonardo appears to have believed that turning the spiral would force air downward and lift the machine. Modern analysis shows that a practical version would require far more power than human operators could provide, so it was a concept rather than a proven aircraft.
The aerial screw is often called a helicopter precursor, but it was not a working helicopter. Modern helicopters use powered rotors with carefully shaped blades and control systems that Leonardo’s sketch did not include.