Leonardo da Vinci’s famous aerial-screw design was a spiral aircraft concept intended to rise by turning a helical surface.
Leonardo drew the device around 1489, describing a large spiral resembling a screw or auger. His notes proposed that a linen-covered frame could press against the air and lift the machine when rotated. The drawing is one of the best-known images from his notebooks and is often cited as an early helicopter-like concept.
The aerial screw was not a working helicopter. Leonardo did not provide a practical engine capable of turning the large rotor quickly enough, and the design’s flight mechanism would not work as drawn with modern aerodynamic understanding. Its historical importance lies in identifying vertical-lift flight as a problem worth solving.
It is commonly mixed up with Leonardo’s ornithopter. The ornithopter uses flapping wings modeled on birds, whereas the aerial screw uses rotary motion and a helical lifting surface. The modern helicopter was developed centuries later through different engineering principles.