Mil Mi-4
The Mil Mi-4 (NATO reporting name 'Hound') is a Soviet transport helicopter built by the Mil Moscow Helicopter Plant. Designed in response to the American H-19 Chickasaw and the Korean War, it first flew in 1952 and entered service in 1953, and for several decades it remained the main helicopter type in the Soviet armed forces and the Civil Air Fleet. More than 4,000 were built, including the Harbin Z-5 production version built in China, and variants filled transport, anti-submarine, search-and-rescue and air-ambulance roles for operators in dozens of countries. The Mi-8 replaced it in Soviet service; survivors are preserved in museums, and a North Korean video released in 2014 showed the type still in limited service there.