Mitsubishi Ki-21 Sally-Gwen Photo Section
Japans Heavy Bombers
SALLY-FORTH
Mitsubishi Ki-21 or Type 97 Heavy Bomber rejoiced in the Allied reporting name of ‘Sally'; however the Ki-21 had more than one Allied codename! Initially called 'Jane', the name was quickly changed to 'Sally' when General MacArthur objected to this, as it was the same name as 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 in fact a new version of the Ki-21, it was renamed ‘Sally 3', with ‘Sally 1' referring to the earlier Ha-5 powered models, and ‘Sally 2‘ referring to the Ha-101 powered Ki-21-IIa. Its all a bit confusing!
The Ki-21 was the Japanese Imperial Army's most important heavy bomber of the time and it's began operations during the Second Sino-Japanese War, participating in the ‘Nomonhan Incident', and in the first stages of the Pacific War. It was also used to attack targets as far away as Western China, India and Northern Australia. In 1936, Imperial Japanese Army Air Service issued a requirement for a new twin-engined heavy bomber, to replace both the Ki-20 and Ki-1, and this design called for a crew of at least four, a top speed of 250mph, endurance of at least five hours, and a bomb-load of 1,6501b. These design parameters were very ambitious, as few twin-engine bombers anywhere in the world could exceed such performance specifications at that time. Both Mitsubishi and Nakajima were asked to build two prototypes each each, with a further proposal from Kawasaki being rejected.
The Mitsubishi design was an all-metal mid-wing monoplane with a ventral bomb-bay and radial engines, and first flew on 18 December 1936, with the second prototype, which differed by 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 andNakajima's proposed 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 825 hp Ha-6 radial engines for the Nakajima Ha-5’s used by the Nakajima. The Ki-21 also 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 as the ‘Army Type 97 Heavy Bomber Model 1A’, being ordered into production in November 1937. Several improved versions followed before the production of the type ended in September 1944 with 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 and was followed by the Ki-21-lb, an improved version designed to address the armament issue and increased the number of 7.7mm (,330in) Type 89 machine guns to five, with a remote controlled tail ‘stinger’ gun also added. Other improvements were made to the horizontal tail surfaces and training edge flaps, the bomb bay was enlarged, and the fuel tanks were partially protected with laminated rubber sheets. This was followed by the Ki-21 -Ic with a 130 US gallon auxiliary fuel tank fitted in the rear weapons-bay, and with one more 7.7mm (,303in) machine gun being added, bringing the total to six. Four 1101b bombs were also now carried externally, and to offset the increase in weight, the main wheels of were also increased in size.
Despite these improvements, by the time of the attack on Pearl Harbor most of the Ki-21-la/lb and lc’s had been relegated to training or second-line duties. Front line units from mid-1940 were equipped with the Ki-21 -Ila ‘Army Type 97 Heavy Bomber Model 2A’ with the more powerful 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. However, starting from operations over Burma in December 1941 and early 1942, the Ki-21 began to suffer heavy casualties from Allied fighters, and to partially compensate the IJAAF introduced the Ki-21-IIb, with a pedal-operated turret containing a single 12.7mm (0.50 in) machine gun, revised canopies, and an increased fuel capacity.
Although used in all fronts in the Pacific Theatre, it became clear by 1942 that the Ki-21 was rapidly becoming obsolete, and was therefore increasingly shifted away from frontline service. However, in spite of its shortcomings the Ki-21 remained in service until the end of the war being utilised as transport (along with the civil transport version MC-21), as a bomber crew and paratrooper training aircraft as well as for liaison, communications, special commando, secret missions, and Kamikaze operations. Some nine Ki-21-Ia/b's were sold to Thailand in 1940 for use by against the Vichy French forces in French Indochina, but they did not participate in the French-Thai War, as the crews had not completed training.
Magazine article: Scale Aviation Modeller International Ki-21 Sally Mar 2015
Magazine article: Scale Aviation Modeller International Ki-21 Sally Mar 2015
Photo: American bombers A-20 Havoc over the Japanese airfield. The picture was taken one second after the fall of one of the bombers (in the background.) In the foreground is partially dismantled the Japanese medium bomber Mitsubishi Ki-21-IIb. The Airfield in the Dutch East Indies (now Indonesia). The Japanese Army Air Division was almost completely destroyed (about 250 aircraft were destroyed or seriously damaged.) The raid was well prepared and provided. It took part 499 th, 498 th, 500 th and 501 th Bomber Squadron on the B-25, and 90 Squadron at the A-20 Havoc. With the support of P-38J and P-40N of the 5th Air Force U.S. Air Force.
Photo: A Japanese Mitsubishi Ki-21 Destroyed on the ground by US Navy fighters at Luzon in the Philippines 1945
Admiral Isoroku Yamamoto | A6M Operators |
Japanese Aces by service and highest number of Kills | Imperial Japanese Naval air units |
Japanese Aces by Full Name | Japanese Aces by Surname |
Chronology of the USN in WWII | ||||||
1939 | 1940 | 1941 | 1942 | 1943 | 1944 | 1945 |
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Editor for Asisbiz: Matthew Laird Acred
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