Leonardo da Vinci’s vertical-lift aircraft concept was the aerial screw. He sketched it around 1489, describing a helical device intended to screw upward through the air.
The design used a large linen-covered helical surface wound around a central mast. Leonardo reasoned that if the structure were rotated rapidly, it might rise like a screw moving through a solid material. The drawing is often called an early helicopter concept, although it could not have flown as shown because the proposed materials and human power were inadequate.
The aerial screw is not the same as Leonardo’s ornithopter, which imitated the flapping motion of birds, or his parachute, which was intended for controlled descent. Modern helicopters use powered rotors that generate lift aerodynamically, while the aerial screw relied on a speculative screw-like principle. Its importance lies chiefly in anticipating vertical flight rather than in being a practical aircraft.