Leonardo da Vinci sketched an aerial screw as a possible machine for lifting a craft vertically.
Drawn around 1489, the aerial screw has a helical surface wrapped around a central mast. Leonardo reasoned that if the screw rotated quickly enough, its spiral surface could “screw” through the air and raise the machine. The concept is often described as an early ancestor of the helicopter.
The drawing shows a large framework with a linen-covered helical blade. Leonardo’s design did not include an engine capable of supplying the necessary power, and the proposed structure would have been too heavy for practical flight. It therefore remained a conceptual experiment in aerodynamics.
The aerial screw should not be confused with a modern helicopter rotor. A helicopter rotor produces lift with aerodynamic airfoils rotating around a shaft, while Leonardo’s sketch used a continuous helical surface. Its historical importance is that it recognized vertical lift as a distinct engineering problem centuries before powered helicopters appeared.