Mitsubishi Ki-57

The Mitsubishi Ki-57 was a Japanese passenger transport aircraft, developed from the Ki-21 bomber, during the early 1940s.

Development
In 1938, when the Ki-21 heavy bomber began to enter service with the Imperial Japanese Army, its capability attracted the attention of the Imperial Japanese Airways. In consequence, a civil version was developed and this, generally similar to the Ki-21-I and retaining its powerplant of two 708 kW Nakajima Ha-5 KAI radial engines, differed primarily by having the same wings transferred from a mid- to low-wing configuration and the incorporation of a new fuselage to provide accommodation for up to 11 passengers. This transport version appealed also to the navy, and following the flight of a prototype in August 1940 and subsequent testing, the type was ordered into production for both civil and military use.

This initial production Ki-57-I had the civil and military designations of MC-20-I and Army Type 100 Transport Model 1, respectively. A total of 100 production Ki-57-Is had been built by early 1942, and small numbers of them were transferred for use by the Japanese navy in a transport role, then becoming redesignated L4M1. After the last of the Ki-57s had been delivered production was switched to an improved Ki-57-II, which introduced more powerful 805 kW Mitsubishi Ha-102 14-cylinder radial engines installed in redesigned nacelles and, at the same time, incorporated a number of detail refinements and minor equipment changes. Civil and military designations of this version were the MC-20-II and Army Type 100 Transport Model 2, respectively. Only 406 were built before production ended in January 1945. Both versions were covered by the Allied reporting name "Topsy".

Variants



 * Ki-57-I Army Type 100 Transport Model 1: Powered by two 708 kW Nakajima Ha-5 KAI radial engines and a redesigned fuselage to accommodate 11 passengers. About 100 aircraft of this type were built including the civil version.
 * MC-20-I: Same as above but built for civil use with Imperial Japanese Airways (Dai Nippon Koku KK).
 * Ki-57-II Army Type 100 Transport Model 2:Powered by two 805 kW Mitsubishi Ha-102 Zuisei 14-cylinder radial engines installed in redesigned nacelles. Minor equipment and detail refinements were also incorporated. 306 aircraft of this type were produced before the end of production in January 1945.
 * MC-20-II: Same as above but built for civil use with Imperial Japanese Airways (Dai Nippon Koku KK).
 * L4M1: A small number of Ki-57-Is were transferred for test by the Japanese navy as transports and were redesignated L4M1.

Wartime
Military operators
 * Imperial Japanese Army Air Force
 * Imperial Japanese Navy Air Service
 * Imperial Japanese Navy Air Service


 * Manchukuo
 * Manchukuo Imperial Air Force

Civil operators
 * 🇯🇵 Japan
 * Imperial Japanese Airways (Dai Nippon Koku KK)
 * Asahi Shimbun
 * Osaka Mainichi Shimbun
 * Tyuka Koku Kaisya (in China)


 * Manchukuo
 * Manchukuo National Airways (in Manchuria)


 * [[File:Flag of the Republic of China-Nanjing (Peace, Anti-Communism, National Construction).svg|23px|link=Reorganized National Government of China]] Reorganized National Government of China
 * One MC-20 used as presidential transport


 * Second Philippine Republic
 * One MC-20 used as presidential transport

Post-war

 * The last Ki-57 was used as a trainer and retired in 1952.
 * Imperial Japanese Airways (till October 1945)
 * Captured aircraft, used by the KNIL.
 * Imperial Japanese Airways (till October 1945)
 * Captured aircraft, used by the KNIL.
 * Captured aircraft, used by the KNIL.

Accidents and incidents

 * On 20 December 1940, an Imperial Japanese Airways MC-20-I (J-BGON, Myuko) crashed into Tokyo Bay off Chiba during CAB's test flight, killing all 13 on board including 8 CAB inspectors.
 * On 21 June 1941, a Manchurian Air Transport MC-20 (M-604) crashed into the Sea of Japan, killing all 18 on board.