Leonardo da Vinci's screw-shaped design for vertical flight is called the aerial screw.
Leonardo drew the aerial screw in a notebook dated approximately 1489. The design has a large helical surface made from linen and reed, mounted on a framework. Leonardo proposed that people could turn a central shaft and force the screw upward through the air, using a principle he compared with a screw moving through a solid material.
The aerial screw is often described as a helicopter ancestor, but it could not have flown as drawn. Human muscle power would not have been enough to rotate the large rotor rapidly, and the structure lacked the lightweight engine and flight controls needed for a practical aircraft. Its historical value lies in identifying the possibility of vertical lift through a rotating spiral surface. The modern helicopter uses rotating blades and powered rotors, not Leonardo's solid helical sail. The drawing nevertheless became one of the best-known examples of Leonardo's interest in aviation.