Leonardo da Vinci’s aerial screw used a screw-like rotor to suggest vertical flight.
Leonardo drew the design around 1489. It showed a large helical sail made from linen, supported by a reed framework and reinforced with wire. Leonardo reasoned that if the screw turned rapidly enough, its surface would bite into the air and lift the structure.
The aerial screw is often called a helicopter ancestor, but it was not a working helicopter. The drawing does not provide a practical engine, and the materials and human power available in Renaissance Italy could not have produced enough lift. Its importance lies in the early attempt to apply the geometry of a screw to flight.
People sometimes confuse it with Leonardo’s ornithopter, which proposed flapping wings. The aerial screw instead used rotary motion, a principle later central to helicopter design.