Leonardo da Vinci’s cone-shaped, rotating-wing flying-machine design is called the aerial screw.
Leonardo drew the aerial screw around 1489 in one of his notebooks. The design shows a large helical rotor made from reeds and linen, supported by a circular frame. Leonardo reasoned that the rotating surface could “screw” upward through the air, much as a screw moves through a material.
The aerial screw is often described as a forerunner of the helicopter, but it was not a practical helicopter. Its materials and human-powered mechanism could not generate enough lift for sustained flight. Modern helicopters use powered rotors, carefully shaped blades, and controls that Leonardo’s sketch did not provide.
The drawing remains important because it demonstrates Leonardo’s habit of applying mechanical principles to natural phenomena. His studies of birds, air resistance, and motion influenced several other flying-machine concepts, including a parachute and an ornithopter.