Leonardo da Vinci’s cone-shaped aircraft concept is known as the aerial screw.
Leonardo sketched the aerial screw around 1489. The design had a large helical surface made from reeds and linen, supported by a framework. He reasoned that rotating the screw could force air downward and lift the structure upward, an idea that resembles the basic principle of a helicopter rotor.
The drawing does not provide a practical power source capable of turning the screw fast enough. The proposed craft was also far too large and heavy for the human muscle power available at the time. It was therefore a theoretical machine, not a successful flying aircraft.
The aerial screw is often called a helicopter ancestor, but it was not a helicopter in the modern engineering sense. Modern helicopters use powered rotors, aerodynamic blades, and control systems. Leonardo’s design is historically important because it shows an early attempt to explain vertical flight through a rotating lifting surface.