Leonardo da Vinci designed the aerial screw as a precursor to the modern helicopter.
His drawing, produced around 1489, shows a large helical rotor made from reeds, linen, and wire. Leonardo reasoned that the spiral surface could screw upward through the air if turned rapidly, much as a screw moves through a material.
The aerial screw was a theoretical machine rather than a tested flying vehicle. Its proposed structure was far too large and heavy for the materials and power sources available in Renaissance Italy. Modern helicopters use powered rotors and aerodynamic principles that Leonardo did not fully know.
The design is often called a helicopter ancestor, but Leonardo did not build a working helicopter. His other flight studies included the ornithopter, which imitated bird wings, and the parachute, which addressed controlled descent rather than powered lift.