What was the main purpose of Leonardo da Vinci’s famous aerial screw design?

Leonardo da Vinci’s aerial screw was intended to achieve vertical flight.

Drawn around 1489, the design shows a large helical surface resembling a screw or a modern helicopter rotor. Leonardo reasoned that if the screw-shaped structure could rotate quickly enough, it might “screw” itself upward through the air. The concept was made from a frame covered with reed and linen.

The aerial screw was not a working helicopter. Its proposed materials, size, and human power source would not have produced enough lift for practical flight. Modern helicopters instead use powered rotor blades shaped and controlled to generate lift efficiently.

Even so, the drawing is historically important. It demonstrates Leonardo’s attempt to apply mechanical principles to aviation more than four centuries before powered helicopters became possible.