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Ki-57
Ki-57
	MC-20-I, with a nickname Asagumo (morning cloud), used by Asahi Shimbun
General information
Type	Transport aircraft; Paratroop transport; Passenger aircraft
Manufacturer	Mitsubishi Heavy Industries
Primary users	Imperial Japanese Army Air Force Imperial Japanese Navy Air Service; Imperial Japanese Airways
Number built	406
History
Manufactured	1940–1945
Introduction date	1942
First flight	August 1940
Developed from	Mitsubishi Ki-21

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 (950 hp) 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.^[1]

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 (1,080 hp) 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".^[2]

Variants

Ki-57-I Army Type 100 Transport Model 1: Powered by two 708 kW (950 hp) 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 (1,080 hp) 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.

Operators

Wartime

Military operators

Japan

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)

Reorganized National Government of China

One MC-20 used as presidential transport

Second Philippine Republic

One MC-20 used as presidential transport

Post-war

China

The last Ki-57 was used as a trainer and retired in 1952.

Japan

Imperial Japanese Airways (till October 1945)^[3]

Netherlands

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.^{[citation needed]}
On 21 June 1941, a Manchurian Air Transport MC-20 (M-604) crashed into the Sea of Japan, killing all 18 on board.^{[citation needed]}

Specifications (Ki-57-II)

Data from Japanese Aircraft of the Pacific War ^[4]

General characteristics

Crew: 4 (pilot, co-pilot, navigator and radio operator)
Capacity: 11 passengers
Length: 16.1 m (52 ft 10 in)
Wingspan: 22.6 m (74 ft 2 in)
Height: 4.86 m (15 ft 11 in)
Wing area: 70.08 m² (754.3 sq ft)
Empty weight: 5,585 kg (12,313 lb)
Gross weight: 8,173 kg (18,018 lb)
Max takeoff weight: 9,120 kg (20,106 lb)
Powerplant: 2 × Mitsubishi Ha-102 Zuisei 14-cylinder air-cooled radial engine, 805 kW (1,080 hp) each for take-off
Propellers: 3-bladed variable-pitch propellers

Performance

Maximum speed: 470 km/h (290 mph, 250 kn) at 5,800 m (19,000 ft)
Range: 3,000 km (1,900 mi, 1,600 nmi)
Service ceiling: 8,000 m (26,000 ft)
Time to altitude: 5,000 m (16,000 ft) 15 minutes 45 seconds
Wing loading: 116.6 kg/m² (23.9 lb/sq ft)

References

^ Francillon 1979, pp. 182–183
^ Francillon 1979, pp. 183–184
^ Francillon 1979, p. 184.
^ Francillon 1979, pp. 184–185.

Bibliography

Francillon, Ph.D., René J. The Mitsubishi Ki-21 (Aircraft in Profile number 172). Leatherhead, Surrey, UK: Profile Publications Ltd., 1967.
Francillon, René J. (1979). Japanese aircraft of the Pacific War. London: Putnam. ISBN 0-370-30251-6. OCLC 6124909. (new edition 1987 by Putnam Aeronautical Books, ISBN 0-85177-801-1); 3rd edition 1987 by Putnam Aeronautical Books, 1987. ISBN 0-85177-801-1).