# 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 (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 eleven 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 one-hundred 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.

## 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

* Imperial Japanese Army Air Force
* 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)

#### 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)

#### 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.
* On 21 June 1941, a Manchurian Air Transport MC-20 (M-604) crashed into the Sea of Japan, killing all 18 on board.

## Specifications (Ki-57-II)

Data from Japanese Aircraft of the Pacific War
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 m$^2$ (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/m$^2$ (23.9 lb/sq ft)