Leonardo da Vinci’s aerial screw was a large helical-rotor design intended to rise vertically through the air.
Drawn in Leonardo’s notebooks around 1489, the aerial screw resembles a giant screw or modern helicopter rotor. The drawing shows a linen-covered helical surface mounted around a central framework. Leonardo proposed that rapidly turning the screw would “screw” itself upward through the air, much as a screw advances through a solid material.
The concept is an important ancestor of the helicopter, but it was not a working helicopter. Its structure was too large and heavy for the materials and power sources available in Renaissance Europe. Leonardo did not provide a complete practical engine or a demonstrated method capable of producing sustained lift.
The aerial screw is sometimes called Leonardo’s helicopter, but that label can be misleading. A modern helicopter uses powered rotors with carefully shaped blades and control systems, whereas Leonardo’s sketch presents an early theoretical approach to vertical flight. The design nevertheless shows his ability to transfer familiar mechanical principles into a radically new invention.