Mil Mi-4
The Mil Mi-4 (USAF/DoD reporting name "Type 36", NATO reporting name "Hound") is a Soviet transport helicopter that served in both military and civilian roles. Design and development. 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 strongly resembles the H-19 Chickasaw in general layout, including the innovative engine position in front of the cockpit, it is a larger helicopter, able to lift more weight and built in larger numbers. The first model entered service in 1953. The helicopter was first displayed  to the outside world in 1952 at the Soviet Aviation Day in Tushino Airfield. One Mi-4 was built with a jettisonable rotor. It served as an experimental vehicle for future pilots' means of safety and ejection designs. Operational history. The Mi-4 transport helicopter laid the beginning of the Soviet Army Aviation. It was widely used both in the armed forces and in Soviet civil aviation, and for several decades remained the main type of helicopter in the inventory of the Soviet Armed Forces and of the Civil Air Fleet. The Mi-4 went out of service with the development of the  Mi-8. It is no longer used by the Russian Air Force, though it remained in service in some countries as a utility helicopter or as a military transport a while longer. Albania was thought to be the final country using the helicopter and by 2005 all were out of service. The Mi-4 played a very important role in the Bangladesh liberation war of 1971. The Mi-4 was the workhorse of the Indian Air Force covering the medium lift role at the time. A highly successful heli-borne operation, the Meghna Heli Bridge, using Mi-4s helped the Indian Army's 57  Mountain Division clear the Meghna River. The helilift of a battalion of Indian troops to the outskirts of Sylhet was the first heli-borne operation of the Indian army. Much like the UH-1 Huey, after it was gradually phased out of military service, it was used in various domestic roles: search and rescue, firefighting, polar expeditioning, construction site cargo helicopter, commercial flights and many others. An official video of a North Korean Air Force combat flying skills competition released in 2014 shows that the Mi-4 is still in limited service in North Korea.