Leonardo da Vinci sketched a helicopter-like device called the aerial screw.
The aerial screw appears in one of Leonardo’s manuscripts, generally dated to about 1489. It consists of a large helical rotor made from reed, linen, and wire, supported by a framework. Leonardo reasoned that if the screw rotated rapidly enough, its spiral surface would bite into the air and raise the structure.
The concept is frequently described as a predecessor of the helicopter, but it was not a working helicopter. Leonardo had no lightweight engine capable of supplying the necessary power, and the design did not include the sophisticated rotor control systems needed for stable flight. It was probably a study of the possibility of aerial propulsion rather than a complete aircraft.
The aerial screw is also commonly confused with Leonardo’s ornithopter. The ornithopter uses flapping wings modeled on birds, whereas the aerial screw uses rotation. The sketch remains historically important because it shows Leonardo thinking about vertical lift more than four centuries before practical helicopters appeared.