Leonardo da Vinci’s aerial screw most closely resembles a helicopter.
Leonardo drew the aerial screw in a manuscript usually dated to about 1489. The design shows a large helical surface around a central shaft. Leonardo reasoned that turning the screw could make the device rise by pushing against the air, much as a screw advances through a material.
The aerial screw was not a functioning helicopter. Leonardo did not have a sufficiently powerful, lightweight engine, and the design would have been difficult to stabilize and control. Modern helicopters instead use powered rotors with carefully shaped blades and systems for controlling lift, thrust, and direction.
The drawing is historically important because it presents an early conceptual predecessor to vertical flight. It should not be described as the first helicopter itself. The first practical helicopters appeared more than four centuries later, after engines and rotor technology had developed.