Leonardo da Vinci's rotating-aircraft design using a helical linen sail was the aerial screw.
Leonardo drew the aerial screw in the 1480s, probably around 1489. Its design shows a large spiral surface supported by a framework and intended to rotate so that it would push against the air and lift the machine. The concept is often described as an early ancestor of the modern helicopter, although it was not a practical powered helicopter.
The drawing belongs to Leonardo's broader investigations of flight, which included studies of birds, wings, parachutes, and mechanical force. The aerial screw has no demonstrated engine capable of turning it, and its proposed materials would not have produced enough lift with human power. It therefore remained a theoretical machine rather than a tested invention.
A common mix-up is calling the sketch a helicopter. Helicopters use powered rotors and aerodynamic lift; Leonardo's design used a rotating helical surface and was never built successfully in his lifetime.