Leonardo da Vinci’s aerial screw is widely regarded as an early helicopter concept.
Leonardo drew the aerial screw around 1489. The design shows a large helical rotor made from linen, reeds, and wire, mounted on a platform. He proposed that people could turn the mechanism and generate enough lift to rise vertically, although the machine could not have flown under human power as drawn.
The aerial screw was an investigation into the physics of flight rather than a working helicopter. Its rotating screw-like surface anticipated the principle of a rotor, but it lacked a practical engine, suitable materials, and a reliable way to transmit power. Modern helicopters use powered rotors and aerodynamic blades rather than Leonardo’s continuous helical surface.
The sketch is commonly called a helicopter because of its resemblance to later rotorcraft. Strictly speaking, Leonardo did not build a helicopter, and the drawing predates powered aviation by centuries.