Leonardo da Vinci’s rotating-blade aircraft concept is known as the aerial screw.
Leonardo drew the aerial screw around 1489, describing a large spiral rotor made from linen stiffened with reeds. His notes suggested that the spiral would “screw” itself upward through the air if rotated rapidly. The design is often called an early helicopter concept because it uses a rotating lifting surface rather than flapping wings, although Leonardo did not build a powered prototype.
The aerial screw could not have flown as drawn because the materials and available power in Renaissance Europe were insufficient. Modern helicopter rotors also depend on aerodynamic principles and engines that Leonardo did not possess. The sketch is nevertheless important in the history of aviation because it shows Leonardo exploring vertical flight more than four centuries before practical helicopters appeared.