Leonardo da Vinci’s screw-powered aircraft concept is commonly called the aerial screw.
Leonardo sketched the design around 1489 or 1490. It showed a large helical sail or screw made from reeds, linen, and wire, mounted around a central shaft. Leonardo reasoned that rotating the screw could force air downward and lift the machine upward.
The aerial screw is often described as a forerunner of the helicopter, but it was not a helicopter in the modern engineering sense. The sketch does not provide a practical engine, control system, or tested method for generating enough lift. Its proposed human-powered mechanism would also have been inadequate for sustained flight.
The idea belongs to Leonardo’s broader studies of flight, in which he examined birds, air resistance, gliding, and mechanical propulsion. Its importance lies in identifying a rotary lifting principle long before powered helicopters became practical. The term “aerial screw” is therefore more precise than simply calling it a helicopter.