Leonardo da Vinci dated his famous aerial-screw sketch to 1489.
The aerial screw appears in Leonardo’s Codex Atlanticus, where he explored a machine intended to rise vertically through the air. The drawing shows a large spiral framework, often compared with a giant screw or helix. Leonardo believed that rotating the structure could generate upward movement.
The date matters because the sketch predates powered helicopters by more than four centuries. It demonstrates that Leonardo was thinking about vertical flight long before engines and lightweight materials made practical rotorcraft possible.
The aerial screw was not a helicopter blueprint in the modern engineering sense. It lacked a suitable power plant and would have faced major problems involving weight, torque, and aerodynamic efficiency. Its historical importance is as a bold mechanical concept, not as a successfully tested aircraft.