Leonardo da Vinci’s rotating flight machine sketched around 1489 is known as the aerial screw.
The design shows a large helical sail mounted on a vertical structure. Leonardo proposed that rapidly turning the screw could force air downward and lift the machine, an idea often compared with the operation of a modern helicopter rotor.
However, the aerial screw could not have flown as drawn because human-powered machinery of the period lacked sufficient power, and the design had no practical system for controlling or stabilizing flight. It therefore remained a concept rather than a working aircraft.
The aerial screw is sometimes called a helicopter precursor, but it was not itself a helicopter. Leonardo’s separate studies of flapping wings explored a different approach to flight.