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27-649: 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

54-419: A lack of armament and self-sealing fuel tanks , while the aircraft's oxygen system also proved unreliable. The Ki-21-Ib was an improved version designed to address the armament issue by increasing the number of 7.7 mm (0.303 in) Type 89 machine guns to five, and incorporating improvements to the horizontal tail surfaces and trailing edge flaps . In addition, the bomb bay was enlarged. The tail gun

81-635: 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

108-521: The Fiat BR.20 bombers which had been purchased as an interim measure. Several improved versions followed before the production of the type ended in September 1944. A total of 2,064 aircraft were built, 1,713 by Mitsubishi and 351 by Nakajima. The Ki-21-Ia was used in combat in the war with China by the 60th Sentai from autumn 1938, carrying out long-range unescorted bombing missions in conjunction with

135-740: 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". Military operators Civil operators Data from Japanese Aircraft of the Pacific War General characteristics Performance Related development Related lists Mitsubishi Ki-21 The Mitsubishi Ki-21 , formal designation " Type 97 Heavy Bomber " ( 九七式重爆撃機 , Kyūnana-shiki jūbakugekiki )

162-655: The Nakajima Ha-5 engines used by the Nakajima design and vice versa, while the Ki-21 gained a revised glazed nose similar to that of the Ki-19 and revised tail surfaces. Thus modified, the Ki-21 proved superior and was ordered into production in November 1937 as the "Army Type 97 Heavy Bomber Model 1A". Production aircraft began to enter service in August 1938, supplementing and then replacing

189-779: The Royal Thai Air Force against Vichy French forces in French Indochina but did not participate in the French-Thai War as its crews had not completed training. Towards the end of the war, remaining Ki-21s were used by Giretsu Special Forces in strikes against American forces in Okinawa and the Ryūkyū Islands . One of the noted operations was an attack on the Allied-held Yontan airfield and Kadena airfield on

216-625: The reporting names " Sally " /" Gwen ". In 1936, the Imperial Japanese Army Air Service issued a requirement for a new heavy bomber to replace both the Ki-20 (Army Type 92 Heavy Bomber) and the Ki-1 (Army Type 93 Heavy Bomber). The design called for a crew of at least four, top speed of 400 km/h (250 mph), endurance of at least five hours, and a bombload of 750 kg (1,650 lb). The design parameters were very ambitious for

243-641: The BR.20 equipped 12th and 98th Sentai s. The Ki-21 proved to be more successful than the BR.20, having a longer range and being more robust and reliable. Two more Sentai s, the 58th and 61st deployed to Manchuria in the summer of 1939 for operations against China, with aircraft from the 61st also being heavily used against Russian and Mongolian Forces during the Nomonhan Incident in June–July 1939. Losses were high during early combat operations, with weaknesses including

270-558: 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

297-549: The Ki-21 began to suffer heavy casualties from Curtiss P-40s and Hawker Hurricanes . To partially compensate, the IJAAF introduced the Ki-21-IIb , with a pedal-operated upper turret with one 12.7 mm (0.50 in) Type 1 machine gun , redesigned cockpit canopies and increased fuel capacity. Although used in all fronts in the Pacific theater, it became clear by 1942 that the design

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324-656: The Nakajima's licensed-produced version of the Douglas DC-2 commercial airliner project, and the short-lived LB-2 long-range attack bomber project for the Imperial Japanese Navy . The Ki-19 was a mid-wing cantilever monoplane of all-metal construction with fabric-covered control surfaces . The aircraft had a bomb bay within a very streamlined fuselage as opposed to carrying the bombs externally. Douglas-type hydraulically -operated retractable landing gear and split- flaps were used. Performance testing by

351-602: The Tachikawa Army Air Technical Research Institute with the competing Mitsubishi Ki-21 lasted from March to May 1937. Evaluation was continued at the Army's main bomber base at Hamamatsu for bombing and other operational testing beginning in June. Not completely satisfied with the combinations of airframe and engines, the Army ordered to both Ki-19 prototypes to be powered by Mitsubishi Ha-6 engines, while

378-448: The earlier Ha-5 powered models, and "Sally 2" referring to the Ha-101 powered Ki-21-IIa. Data from The Concise Guide to Axis Aircraft of World War II General characteristics Performance Armament Related development Aircraft of comparable role, configuration, and era Related lists Nakajima Ki-19 The Nakajima Ki-19 ( 中島 キ19 , Ki-jyukyu )

405-623: The increase in weight, the main wheels of the Ki-21-IC were increased in size. However, by the attack on Pearl Harbor and the start of the Pacific War , improvements in the ROC Air Force caused losses to mount, and most Ki-21-1a, -1b and -1c were relegated to training or second-line duties. Front line units from mid-1940 were equipped with the Ki-21-IIa ("Army Type 97 Heavy Bomber Model 2A") with

432-434: The mid-1930's; few twin-engine bombers anywhere in the world could exceed such performance at that time. Both Mitsubishi and Nakajima were asked to build two prototypes each, a further proposal from Kawasaki was rejected. The Mitsubishi design was an all-metal mid-wing cantilever monoplane with retractable landing gear , ventral bomb bay and two radial engines . The first prototype flew on 18 December 1936, with

459-1227: The more powerful 1,118 kW (1,500 hp) Mitsubishi Ha-101 air-cooled engines and larger horizontal tail surfaces. This became the main version operated by most IJAAF heavy bomber squadrons at the beginning of the Pacific War and played a major role in many early campaigns. For operations over the Philippines , the JAAF's 5th, 14th and 62nd Air Groups, based in Taiwan , attacked American targets at Aparri , Tuguegarao , Vigan and other targets in Luzon on 8 December 1941. The 3rd, 12th, 60th, and 98th Air Groups, based in French Indochina, struck British and Australian targets in Thailand and Malaya , bombing Alor Star , Sungai Petani and Butterworth under escort by Nakajima Ki-27 and Ki-43 fighters. However, starting from operations over Burma in December 1941 and early 1942,

486-482: The name was quickly changed to "Sally" when General Douglas MacArthur objected that the name was the same as that of his wife. When the Ki-21-IIb entered service, the absence of the long dorsal "greenhouse" led Allied observers to mistake it for a completely new type, which was designated "Gwen". However, when it was realized that "Gwen" was a new version of the Ki-21, it was renamed "Sally 3", with "Sally 1" referring to

513-667: The night of 24 May 1945. Twelve Ki-21-IIb's of the Daisan Dokuritsu Hikōtai were dispatched for a strike, each with 14 commandos . Five managed to crash-land on the Yontan airfield. Only one plane landed successfully. The surviving raiders, armed with submachine guns and explosives, then wrought havoc on the supplies and nearby aircraft, destroyed 70,000 US gallons (260,000 L) of fuel and nine aircraft, and damaged 26 more. A number of Ki-21-Ia were modified to serve as military transports for use by Greater Japan Airways , which

540-593: The second prototype, which differed in replacing the dorsal turret of the first prototype with a long greenhouse canopy, following later in the month. In the resulting competition, Mitsubishi's Ki-21 and Nakajima's Ki-19 were found to be similar, with the Ki-21 having better performance, while the Nakajima design was a better bombing platform and had more reliable engines. In order to make a final decision, two further prototypes were ordered from both Mitsubishi and Nakajima, with Mitsubishi instructed to change its own 615 kW (825 hp) Mitsubishi Ha-6 radial engines for

567-520: The two prototypes of the Mitsubishi Ki-21 also converted to be powered by Nakajima Ha-5 engines. Prototypes from the two companies were almost identical in performance, but the Army officially selected the Mitsubishi Ki-21 as the "Army Type 97 Heavy Bomber", Nakajima having lost the Army contract. The fourth prototype was converted to the mail plane in April 1939 it got the new designation N-19 . It

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594-498: Was a 'stinger' installation and was remotely controlled. Also, the fuel tanks were partially protected with laminated rubber sheets. This was followed in production by the Ki-21-Ic with provision for a 500 L (130 US gal) auxiliary fuel tank, fitted in the rear weapons bay and one more 7.7 mm (0.303 in) machine gun, bringing the total to six. Four 50 kg (110 lb) bombs were carried externally. To offset

621-532: Was a Japanese heavy bomber during World War II . It began operations during the Second Sino-Japanese War participating in the Nomonhan Incident , and in the first stages of the Pacific War , including the Malayan , Burmese , Dutch East Indies and New Guinea Campaigns . It was also used to attack targets as far-flung as western China , India and northern Australia . The Allies designated it under

648-846: Was an unsuccessful attempt by Nakajima Aircraft Company to meet a 1935 requirement issued by the Japanese government for a modern bomber to replace the Mitsubishi Ki-1 heavy bomber . Unlike in earlier projects, the Imperial Japanese Army issued in February 1936 detailed specifications that had to be met by the new aircraft. These included a maximum speed 399 km/h (248 mph) at 3,000 m (9,840 ft); climb to altitude in under eight minutes; take-off in less than 300 m (980 ft); normal operating altitude from 2,000 m (6,560 ft) to 4,000 m (13,120 ft); and endurance of more than five hours at 299 km/h (186 mph) at 3,000 m (9,840 ft). Structural strength

675-482: Was rapidly becoming obsolete, and was increasingly shifted away from front-line service. In spite of its shortcomings, the Ki-21 remained in service until the end of the war, being utilized as transport (along with the civil transport version MC-21 ), bomber crew and paratrooper trainer , glider towing , liaison and communications, special commando and secret missions, and kamikaze operations. Nine Ki-21-Ia/b's were sold by Japan to Thailand in 1940 for use by

702-831: Was specified as well, including a load factor of 6 while at high angle of attack , and 4 while in a glide. Minimum bombload for short-range missions was to be 1,500 kg (3,310 lb) with a variety of load configurations. Loaded, the bomber was to have a weight of less than 1,000 kg (2,200 lb). Other specified requirements were a crew of from four to six; engines to be either the Nakajima Ha-5 or Mitsubishi Ha-6 ; and three gun positions (nose, dorsal and ventral, each with one flexible 7.7 mm (0.303 in) Type 89 machine gun ). The Hi-2 (Type 94) or Hi-5 radio, and other details were also specified. Nakajima's veteran design team included Kenichi Matsumura as chief designer, assisted by Setsuro Nishimura and Toshio Matsuda , all of whom had previous twin-engine design experience on

729-564: Was under contract by the Japanese Army in China for transportation. Designated " MC-21 ", these aircraft had all armament and military equipment removed. Used primarily as cargo transports, each could also seat nine paratroopers. Aircraft built from the start as transports were given the separate designation of Mitsubishi Ki-57 , with equivalent civil aircraft being designated MC-20. The Ki-21 had more than one Allied codename. Initially called "Jane",

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