Leonardo da Vinci’s rotating helical flying concept is called the aerial screw. His 1489 notebook sketch shows a large spiral sail made from reeds and linen wrapped around a central mast, with a platform and four operators turning cranks.
Leonardo reasoned that the spiral surface would “screw” into the air, analogous to a screw moving through a solid material. The idea is an early ancestor of the helicopter, but it could not have lifted itself as drawn because human muscle power was insufficient and the structure would have been extremely heavy.
The aerial screw was a study of vertical flight, not a practical aircraft blueprint. Modern replicas generally use lightweight materials or powered motors to demonstrate the principle. It is distinct from Leonardo’s ornithopter, which sought lift through flapping wings modeled on birds and bats.
The sketch is one of Leonardo’s best-known aviation studies and helped inspire later rotorcraft concepts.