Leonardo da Vinci’s spiral-rotor flying device was the aerial screw. He drew it in the Codex Atlanticus around 1489, imagining that a linen-covered helical surface could screw upward through the air if rotated rapidly.
The design is often called a helicopter predecessor, but it was not a practical helicopter. Leonardo’s aerial screw had no engine, and the materials and power available in the Renaissance could not have produced enough lift for a full-sized machine. Its shape was inspired partly by the idea of a screw moving through a fluid.
The aerial screw is also frequently confused with Leonardo’s parachute and ornithopter designs. A parachute descends by creating drag, while an ornithopter imitates flapping wings. The aerial screw instead depends on rotary lift, the principle later used by helicopter rotors.
Leonardo’s sketch was conceptual rather than a tested invention. Modern replicas have explored whether smaller versions can rise, but these experiments do not prove that the original machine would have flown.