Leonardo da Vinci’s flying machine with a large helical rotor was the aerial screw. He drew the design around 1489–1490 in a notebook now associated with the Codex Atlanticus.
The machine featured a linen-covered helical surface wrapped around a central frame. Leonardo reasoned that if the screw rotated quickly enough, it could “screw” itself upward through the air. The sketch is usually described as an early conceptual ancestor of the helicopter, not as a practical aircraft that Leonardo built.
The aerial screw is often confused with Leonardo’s ornithopter, which used flapping wings modeled on birds and bats. It also differs from the parachute, which was intended to slow a descent rather than provide powered flight.
Modern helicopters use powered rotors and aerodynamic lift, so they do not operate exactly like Leonardo’s proposed screw. Nevertheless, the drawing shows his interest in translating rotary motion into vertical flight, a problem that remained difficult for centuries.