Leonardo da Vinci’s helical linen-sail design intended to lift from the ground is known as the aerial screw.
Leonardo drew the concept around 1489 in a manuscript now held within the Codex Atlanticus tradition. The machine featured a large spiral structure made from reeds and covered with linen. Leonardo suggested that if the screw rotated rapidly, its helical surface would press against the air and raise the device.
The aerial screw is frequently described as an early helicopter ancestor, but it was not a working helicopter. Leonardo supplied no practical engine capable of turning the large rotor quickly enough, and the design lacked several features needed for controlled flight, including a modern tail rotor and reliable control system.
The idea is also distinct from Leonardo’s ornithopter sketches, which attempted to imitate the flapping motion of birds. The aerial screw instead used rotary motion and a continuous helical surface, making it one of the clearest early proposals for vertical lift.