Sikorsky H-19 Chickasaw/S-55 (USA) ✈ Mil Mi-4 (USSR) ✈ Harbin Z-5 (China)

Sikorsky H-19 Chickasaw (USA). First flight: 10 November 1949 (Wiki)

Mil Mi-4 (USSR). First flight: 3 June 1952 (Wiki)

The Mi-4 was designed in response to the American H-19 Chickasaw and the deployment of U.S. helicopters during the Korean War. While the Mi-4 superficially resembles the H-19 Chickasaw, it is a larger helicopter and is able to lift more weight.
— Wikipedia
mi_01.jpg

Harbin Z-5 (China). First flight: 1959 (Wiki)

The Harbin Z-5 (Zhishengji - helicopter) is a Chinese copy of the Soviet Mil Mi-4 piston engined helicopter. It was produced in the city of Harbin, China. The USSR provided China with blueprints in 1958, a few years before the Sino-Soviet split. The first flight was in 1959, but serial production was delayed and did not start until the mid-1960s.
— Wikipedia