Leonardo da Vinci sketched an aerial screw as a possible rotating-wing machine for lifting a craft into the air.
The design appears in a manuscript dated to around 1489 and is often described as a large helical rotor made from reeds, linen, and wire. Leonardo reasoned that the screw could “screw” itself upward through the air if driven fast enough.
The concept resembles the principle behind a helicopter rotor, but it is not a helicopter in the modern engineering sense. Leonardo’s model had no practical engine, and the materials and power available in his era could not have produced the required lift.
The aerial screw is therefore best understood as an imaginative early study of vertical flight. Its historical importance lies in the recognition that a rotating helical surface might generate upward force, even though the design lacked the lightweight engines, rotor control, and structural technology needed for a working aircraft.