Mitsubishi Ki-21 or 'Type 97 Heavy Bomber - 九七式重爆撃機 Allied reporting name: Sally or Gwen

National origin:- Japan
Role:- Bomber, Transport
Manufacturer:- Mitsubishi Heavy Industries
First flight:- 18th December 1936
Introduction:- 1938
Retired:- 1945 (Japan)
Primary users:- Japn, Thai Air Force, post war Indonesia
Produced:- 2,064 units (excluding Ki-57)
Variants:- Mitsubishi Ki-57

Mitsubishi Ki-21 or 'Type 97 Heavy Bomber' - 九七式重爆撃機

Mitsubishi Ki-21 or 'Type 97 Heavy Bomber' - 九七式重爆撃機 Kyūnana-shiki jūbakugekiki (Allied reporting name: Sally - Gwen) was a Japanese 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.

Design and development

In 1936, 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).[1] 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, and few twin-engine bombers anywhere in the world could exceed such performance at that time.[2]

Both Mitsubishi and Nakajima were asked to build two prototypes each, a further proposal from Kawasaki being rejected. The Mitsubishi design was an all-metal mid-wing cantilever monoplane with retractable landing gear, ventral bomb bay and two radial engines.[3] The first prototype flew on 18 December 1936, with the second prototype, which differed in replacing the dorsal turret of the first prototype with a long greenhouse canopy, following later in the month.[4] 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 prototype were ordered from both Mitsubishi and Nakajima, with Mitsubishi instructed to change its own 615 kW (825 hp) Mitsubishi Ha-6 radial engines for the Nakajima Ha-5 engines used by the Nakajima design and vice versa, while the Ki-21 gainied 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.[5]

Production aircraft began to enter service in August 1938, supplementing and then replacing the Fiat BR.20 bombers which had been purchased as an interim measure.[6]

Several improved versions followed (see below) 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.[7]

Operational history

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 the BR.20 equipped 12th and 98th Sentais. The Ki-21 proved to be more successful than the BR.20, having a longer range and being more robust and reliable. Two more Sentais, 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.[6]

Losses were high during early combat operations, with weaknesses including 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 (.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 was a 'stinger' installation, and was remotely controlled. Also, the fuel tanks were partially protected with laminated rubber sheets.[8][9]

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 (.303 in) machine gun, bringing the total to six. Four 50 kg (110 lb) bombs were carried externally. To offset the increase in weight the main wheels of the Ki-21-IC were increased in size.[10][9]

However, by the attack on Pearl Harbor and the start of the Pacific War, improvements in Republic of China Air Force fighter quality and quantities 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 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, 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 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, for 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 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.[11]

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 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 264,979 L (70,000 gal) of fuel and nine aircraft, and damaged 26 more.[12]

A number of Ki-21-Ia were modified to serve as military transports for use by Greater Japan Airways, which 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.

Code Names

The Ki-21 had more than one Allied codename. Initially called "Jane", 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 the earlier Ha-5 powered models, and "Sally 2" referring to the Ha-101 powered Ki-21-IIa.[13]

Variants

Ki-21

Prototype models with various engines and armament combinations for evaluation. Final version with Nakajima Ha-5 engine. 8 built

Ki-21-Ia (Army Type 97 Heavy Bomber, Model IA)

First production model, with 634 kW (850 hp) Nakajima Ha-5-kai engines. Most were built by Mitsubishi, 143 manufactured by Nakajima

Ki-21-Ib (Army Type 97 Heavy Bomber, Model IB)

Improved version with additional 7.7 mm (.303 in) machine guns, larger bomb compartment and flaps, redesigned tail. 120 built by Mitsubishi, 351 (including Ki-21 Ib and Ic) by Nakajima

Ki-21-Ic (Army Type 97 Heavy Bomber, Model IC)

Improved type with one additional 7.7 mm (.303 in) machine gun, increased fuel capacity, 160 built by Mitsubishi

Ki-21-II

Evaluation model with more powerful engines, 4 built

Ki-21-IIa (Army Type 97 Heavy Bomber, Model IIA)

Production model based on Ki-21-II, 590 built

Ki-21-IIb (Army Type 97 Heavy Bomber, Model IIB)

Final production version based on Ki-21-IIa with modified canopy, clear upper cabin replaced by rotating turret, 688 built.

MC-20-I and Army Type 100 Transport Model 1 (Ki-57 'Topsy')

Unarmed civilian transport version, converted from Ki-21-Ia; approximately 100 aircraft were converted for use as unarmed civil freighter/transports.

MC-20-II and Army Type 100 Transport Model 2 (Ki-57 'Topsy')

An improved model with Mitsubishi Ha-102 radials in redesigned nacelles. Also incorporated a number of detail refinements and equipment changes. About 406 aircraft were built before production ended in January 1945.

L4M1 (Ki-57 'Topsy')

A small number of MC-20-I aircraft transferred to the Japanese Navy.

Operators

Japan Imperial Japanese Army Air Force, Imperial Japan Airways (Dai Nippon Kōkū)

Thailand Royal Thai Air Force operated nine Ki-21-I Nagoya

Postwar

Indonesia Indonesian Air Force

Specifications (Ki-21-IIb)

Data from The Concise Guide to Axis Aircraft of World War II[14]

General characteristics
Crew: 5-7
Length: 16.0 m (52 ft 6 in)
Wingspan: 22.50 m (73 ft 10 in)
Height: 4.85 m (15 ft 11 in)
Wing area: 69.90 m² (752.12 ft²)
Empty weight: 6,070 kg (13,354 lb)
Loaded weight: 10,600 kg (23,320 lb)
Propellers: three-blade metal variable-pitch propellers propeller
Powerplant: 2 × Mitsubishi Army Type 100 (Ha-101)(Mitsubishi Kasei) 14 cylinder radial engine, 1,119 kW (1,500 hp) each
Performance
Maximum speed: 485 km/h (301 mph) at 4,700 m (15,400 ft
Cruise speed: 380 km/h (236 mph)
Range: 2,700 km (1,680 mi)
Service ceiling: 10,000 m (32,800 ft)
Rate of climb: 13 min 13 sec to 6,000 m (19,680 ft)
Armament
Guns: 4× 7.7 mm (.303 in) flexible Type 89 machine guns in nose, ventral, beam and tail positions
Guns: 1× 12.7 mm (.50 in) Type 1 Machine Gun in dorsal turret
Bombs: 1,000 kg (2,200 lb) of bombs

 

Mitsubishi Ki-21 Sally-Gwen

Following some incidents with the Russians on the Mongolian frontier at the beginning of 1936, the Japanese Air Headquarters issued the specifications for a twin-engined monoplane heavy bomber to replace the Army Type 92 Heavy Bomber Ki-20. The new bomber would feature either a Nakajima Ha-5 or a Mitsubishi Ha-6 powerplant. In anticipation to its use in the Manchukuo-Siberia area, it had to be able to operate in extreme cold weather.

In answer to this specification, Nakajima submitted its Ki-19, Kawasaki the Ki-22 and Mitsubishi the Ki-21. The Air Headquarters selected both Nakajima and Mitsubishi proposals and ordered competitive projects from both manufacturers. The Mitsubishi project was led by engineers Nakata and Ozawa who completed the first prototype in only nine months after the Headquarters specifications. In November 1937 the Army signed a contract with Mitsubishi to build the officially known as Army Type 97 Heavy Bomber Model I, although Nakajima also received a share of the production aircraft. Once the field units received the first Ki-21s, they started operations in Manchuria. It soon became evident that protection was not enough and the Sentais suffered heavy losses against Russian fighter aircraft fielded by the Chinese. Mitsubishi began to produce the Ki-21-Ib or Army Type 97 Heavy Bomber Model 1B, correcting some major drawbacks detected in early combats. Model Ib was soon followed by Ic with increased armament and fuel load.

From November 1939 Mitsubishi started the building of a new model with air-cooled fourteen-cylinder Mitsubishi Ha-101 engines that featured longer propellers. Tests began in March 1940, and the aircraft was ordered into production as Army Type 97 Heavy Bomber Model IIa. The Ki-21 (codenamed Sally by the Allies) was due to be replaced by Nakajima Ki-49 Donryu new bomber which did not meet the Army expectations and consequently further changes from field experience were made in order to keep Ki-21s updated. The lack of adequate defensive armament and its limited range of fire made Mitsubishi to eliminate the long dorsal 'greenhouse' and replace it by a conical turret housing a flexible 12.7 mm machine-gun. The new version was called Model IIb. Although small equipment changes and improved petrol protection were also introduced, the new aircraft was basically identical to previous versions. The last Ki-21-IIb was delivered in September 1944.

The Mitsubishi Ki-21 (Army Type 97 Heavy Bomber) was produced by engineers Nakata and Ozawa in response to an operational specification issued by the Air Headquarters (Daihonei) of the JAAF on 15 February 1936. The first of two prototypes flew on 18 December 1936, the first production model being the Mitsubishi Ki-21- Ia (Army Type 97 Model 1A). Because of production bottlenecks it was not until the end of 1939 that Ki-21-la bombers equipped the first JAAF unit, the 60th Hikosentai (air regiment) based in China, in totality; the next unit to be equipped was the 61st Sentai. Early lessons learned over China demonstrated lack of firepower and protection, and the Ki-21-Ib and Ki-21-Ic subvariants had extra armour, additional 7.7mm Type 89 machine-guns, more fuel and larger bomb-bays. The engines were 634kW Nakajima Ha-5 KAI radials. By the time of the outbreak of war in December 1941, the majority of the Mitsubishi Ki-21-Ia, Ki-21-Ib and Ki-21-Ic bombers had been relegated to second-line duties, or to service as operational bomber trainers.

First-line bomber sentais had by now received the more powerful Ki-21-II, with 1119kW Mitsubishi Ha-101 engines in modified Cowlings; production models in service in 1941 were the Ki-21-IIa (Army Type 97 Heavy Bomber Model 2A), and the Ki-21-IIb which had a pedal-operated dorsal turret with one 12.7mm Type 1 heavy machine gun. Three sentais remained in Japan, Korea and in Manchuria when the Japanese high command went to war in South East Asia.

For operations over the Philippines the JAAF's 5th Air Group, based in Formosa, mustered the 14th and 62nd Hikosentais; these went into action early on the morning of 8 December 1941 striking at Aparri, Tuguegarao, Vigan and other targets in Luzon. Mitsubishi Ki-21s of the 3rd Air Group, based in French Indo- China, were earmarked for bombing strikes against Siam (Thailand) and Malaya: units were the 12th, 60th and 98th Hikosentais. These smashed RAF and RAAF facilities at Alor Star, Sungei Patani and Butterworth, being escorted by Nakajima Ki-27 and Ki-43 fighters. In the flush of Japanese victory in 1941-2 the Mitsubishi Ki-21, codenamed 'Sally', performed well; only over Rangoon over December 1941 and January 1942 did the Ki-21s suffer heavy casualties. The Ki-21-IIb was the final model to enter service, which was seen on all fronts in the Pacific and Far East theatres. Some 2,064 Ki-21s were built.

Mitsubishi Ki-21 Sally

Winning a production order in November 1937, following competition with Nakajima's Ki-19 prototype, the Mitsubishi Ki-21 was designed and built to meet an Imperial Japanese Army requirement of early 1936 for a four-seat bomber that would have a maximum speed of at least 249 mph (400 km/h) and an endurance of more than 5 hours. Few twin-engine bombers anywhere in the world could exceed such performance at that time and, not surprisingly, the Ki-21 was later recognised as the best bomber in Japanese service during World War II. A cantilever mid-wing monoplane of all-metal construction, the design incorporated retractable tailwheel landing gear, a ventral bomb bay and two radial engines, one mounted in a nacelle at the leading edge of each wing. As first flown, on 18 December 1936, the Ki-21 had 825 hp (615 kW) Mitsubishi Ha-6 radial engines, but competitive evaluation against the Nakajima Ki-19 powered by that company's Ha-5 engine led the army to instruct Mitsubishi to introduce similar engines on the Ki-21. When the aircraft had been tested again with revised vertical tail surfaces and these more powerful engines, the army had no hesitation in ordering the aircraft into production under the designation Army Type 97 Heavy Bomber Model 1A, company designation Mitsubishi Ki-21-Ia. The first of the production aircraft began to enter service in the summer of 1938 but, when used operationally in China later that year , they were soon found to be lacking in defensive armament and self-sealing fuel tanks.

Improved versions were developed to overcome these and other shortcomings, the Ki-21-Ib introducing revised horizontal tail surfaces, larger area trailing-edge flaps, an enlarged bomb bay and armament increased to a total of five 7.7 mm (0.303 in) machine-guns. The generally similar Ki-21-Ic differed by having increased fuel capacity and the addition of one more 7.7 mm (0.31 in) gun. To increase performance four improved Ki-21-Ics were given more powerful Mitsubishi Ha-101 engines and these, redesignated Ki-21-II, were used for service trials. Ordered into production as the Army Type 97 Heavy Bomber Model 2A (Mitsubishi Ki-21-IIa), this version was operated by most of the army's heavy bomber groups at the beginning of the Pacific war. These aircraft played a significant role in. the opening phase of the war, but as Allied resistance began to increase and bomber crews found themselves confronted by fighter aircraft of increased quality and in greater quantity, Ki-21 losses began to rise steeply. Further revisions of defensive armament were made, the Ki-21-IIb replacing the dorsal gun position by a manually operated gun turret containing one 12.7 mm (0.50 in) machine-gun, and this version also introduced redesigned cockpit canopies and individual engine exhaust stacks to give some thrust augmentation. However, it soon became clear that the Ki-21 was gradually becoming obsolescent, and during the last year of the war the maj6rity were relegated to second-line duties. Allocated the Allied codename 'Sally', the Ki-21 was built to a total of 2,064 by Mitsubishi (1,713) and Nakajima (351). From this total a number of Ki-21-la aircraft were modified to serve as freight transports for use by Greater Japan Air Lines. Designated MC-20, these aircraft had all armament and military equipment removed and could, if required, be fitted with nine troop seats.

九七式重爆撃機

九七式重爆撃機
(きゅうななしきじゅうばくげきき、キ21)は、大日本帝国陸軍が九三式重爆撃機の後継として開発した、双発単葉・引込脚の近代的な重爆撃機である。九七式重爆撃機は、爆弾搭載量や航続距離よりも速度を重視した設計がなされ、重爆撃機と名称されながら爆弾の搭載量が外国の同種の機体に比較して少ない。開発は三菱と中島による競合の結果、三菱が担当する事になり(初期型の発動機は中島製だった)、1937年(昭和12年)に正式採用され、陸軍の主力爆撃機として活躍した。連合軍によるコードネームは「Sally」および「Gwen(II型乙が旋回砲塔採用で外観が変った為、当初別機種と思われた模様)」。

開発史

1935年(昭和10年)9月に日本陸軍は九三式重爆撃機の後継機となる重爆撃機の試作を内示し、翌年2月に中島と三菱にそれぞれキ1キ21の試作が指示された(名称については、試作指示時は両者ともキ19で増加試作時に三菱の機体に対して改めてキ21の名称を与えたという資料もある)。主な要求は、双発の単葉機でエンジンは中島製のハ5または三菱製のハ6を装備

最大速度は400km/h以上

航続時間は5時間以上

爆弾搭載量は750kg(最大で1,000kg)

試作機2機を昭和11年10月までに完成

というものだった。三菱では要求された期限より若干遅れた1936年(昭 和11年)12月に、ハ6エンジンを搭載した試作機2機を完成させた。翌年の陸軍による審査では三菱のキ21も中島のキ19も要求値をクリアしており甲乙 付け難い性能を示したが、結局陸軍は三菱の機体を採用することとし代わりにエンジンは中島製のハ5エンジンを搭載することを決定した。この決定に基づいて キ21の増加試作機の生産が指示されたが、増加試作機ではエンジンのハ5への換装の他、中島のキ19が勝っていた機能要素(前方銃座の形状、爆弾倉の形状 等)をキ21に盛り込むことが要求されていた。完成した増加試作機は海軍の九六式陸上攻撃機を上回る高性能を示しており、1937年(昭和12年)に制式採用された。

その後1939年(昭 和14年)にはエンジンの強化を中心とした性能向上型の開発が指示され、昭和15年12月に試作機が完成した。主な変更点はエンジンを1450hpのハ 101に換装したことと、主車輪の完全引き込み式化、防御武装の強化であった。審査の結果大幅な性能向上が認められたため、1940年(昭和15年)12月に九七式二型重爆撃機として制式採用になった。この型は1944年(昭和19年)9月まで生産され、太平洋戦争中の主力型となった。

近代爆撃機に対する設計思想

陸軍の爆撃機に対する設計思想は、爆弾搭載量や航続距離を多少犠牲にしても、敵戦闘機の 迎撃を振り切れる程度の高速性能を確保する事を重視し、爆弾搭載量の不足は反復攻撃を行う事で補うという戦術思想だった。陸軍が重爆軽爆を問わず、爆撃機 に第一に求めていた任務は敵飛行場で敵機を地上で捕捉し破壊することにあった。つまり爆撃機による制空権の確保であり、ノモンハン事件で行われたタムスク爆撃は、妥当性の是非はともあれ、当時の陸軍重爆隊として、最も典型的な作戦実施要領ではあったのである。

従って、敵が迎撃準備を整える前に飛行場上空に到達している必要があった。また、攻撃目標はソ満国境の前線基地であり、長い航続距離の必要はなかった。在 地航空機攻撃のため爆弾倉は比較的小型の爆弾を多数搭載し、死角なく爆撃火網を構成する設計になっているので、ペイロードベースでは最大搭載量が小さく なっている。本機はそのような思想のもとに設計が行われた。

結果的に同時期に存在した敵側の最新鋭戦闘機を振り切るほどの速度はなかったとはいうものの、1938年配備開始の爆撃機としては世界的に見てもかなりの高速機であり、爆弾搭載量は不足していると言われることが多いが、開発目的となっている任務にはよく適合していた。

結局、この陸軍の重爆撃機に対する任務要求は四式重爆撃機まで変わることはなく、以後開発された重爆撃機もまた、いずれも同様の機能性能を備えた。

しかし、こうした機能性能はあまりに対ソ戦のみを見据えていたもので、太平洋戦線の実情にはあまり適合するものとはならなかった。陸軍の重爆撃機は終始開 発時に想定された任務に投入されることのないままに、結果として「爆弾搭載量不足」「航続力不足」「飛行性能不足」といった評価を受けざるを得なくなって しまうのである。

実戦での評価

多少の問題点を含みつつも、初めて開発された近代的爆撃機としては成功作と言えるもので、実戦部隊からの評判も良く、信頼性が高かった。後継機の開 発・実用化の遅れから数々の改良を加えられながら使用され続けたために本機の生産期間は長く、最終的に各型合わせて2,000機以上が量産され、陸軍重爆 撃機ではもっとも多く生産された機体となった。前線部隊においては後継機の百式重爆撃機よりも実用面で優れているとされ、本機の方を好んで使用する部隊もあったといわれる。また、防弾板や自動防漏タンクを装備するなど海軍の一式陸上攻撃機より防弾性能に優れていた。

1943年(昭和18年)夏以降からは旧式化のため次第に後方任務に回されるようになったが、それでも夜間爆撃任務や輸送・連絡、哨戒、グライダーの曳航などの任務で終戦まで活躍を続けた。1945年(昭和20年)5月24日、米軍の占領下にあった沖縄の飛行場で破壊活動を行なった義号作戦で、空挺隊員の空輸に用いられたのも本機である。

輸送機型

本機はその高性能から輸送に用いられることも多かったが、本来の爆撃任務に支障をきたすため、陸軍は本機をベースとして胴体部分を再設計した輸送機の開発を三菱に命じ、百式輸送機(キ57)として採用した。百式輸送機の民間型をMC-20といい、航空会社の旅客機や新聞社の連絡機として使用された。

また、九七式重爆撃機そのものを輸送機に改装した貨物輸送機も数機あり、これは陸軍から大日本航空が払い下げを受けて改装し、MC-21の名で使用した。

主要諸元

全幅: 22.50 m
全長: 16.02 m
全高: 4.35 m
主翼面積: 69.60 m2
自重: 6,070 kg
全備重量: 10,610 kg
乗員: 7 名
最高速度: 478 km/h
巡航速度: 380 km/h
航続距離: 2,400 km
発動機: 三菱ハ101・1500 hp ×2
武装: 7.7 mm機銃 ×5(前方 1、後下方 1、後側方 2、尾部 1)、13 mm機銃 ×1(後上方)
爆弾: 750 - 1000 kg
(主要諸元は2型乙)

Imperial Japanese Army Air Force

The Imperial Japanese Army Air Service (often called the Imperial Japanese Army Air Force (帝国陸軍航空隊, Teikoku Rikugun Kōkūtai) (IJAAF), was the land-based aviation force of the Imperial Japanese Army. As with the IJA itself, the IJAAF was developed along the lines of Imperial German Army Aviation so its primary mission was to provide tactical close air support, for ground troops while maintaining a limited air interdiction capability. The JAAF also provided important reconnaissance support for the Army. However, the Army Air Service usually did not control the light aircraft or balloons deployed and operated by the Imperial Japanese Army artillery battalions as spotters or observers. Although the Army Air Service engaged in limited strategic bombing of major Chinese cities such as Shanghai and Chongqing in the early stages of the Second Sino-Japanese War, this was not its primary mission, and it lacked the heavy strategic bombers as were later deployed by the United States Army Air Force. The Imperial Japanese Navy Air Service was responsible for long-range strikes and strategic air defense and it was not until the later stages of the Pacific War that both services attempted anything like integrated air defense.

History

The Imperial Japanese Army made use of hot air balloons for observation purposes in the Russo-Japanese War on 1904-1905 and purchased its first aircraft, a Farman biplane, in 1910. However, serious interest in military aviation did not develop until after World War I. Japanese military observers in Europe were quick to spot the advantages of the new technology, and after the end of the war, Japan purchased large numbers of surplus military aircraft, including Sopwith 1½ Strutters, Nieuport Bebes, and Spads.

Japanese army aviation was organized into a separate chain of command within the Ministry of War of Japan in 1919, and aircraft were being used in combat roles by the 1920 Siberian Intervention against the Bolshevik Red Army near Vladivostock.

The first aircraft factory in Japan, Nakajima Aircraft Company, was founded in 1916, and later obtained a license to produce the Nieuport 24 and Nieuport 29C1, as well as the Hispano-Suiza engine. Nakajima later license-produced the Gloster Gannet and Bristol Jupiter. Similarly, Mitsubishi Heavy Industries started producing aircraft under license from Sopwith in 1921, and Kawasaki Heavy Industries started producing the Salmson bomber from France, and hired German engineers, such as Dr. Richard Vogt to produce original designs, such as the Type 88 bomber. Kawasaki also licensed production of aircraft engines from BMW. By the end of the 1920s, Japan was producing its own designs to meet all of the needs of its Army, and by 1935 had an inventory that was large and technically sophisticated.

During the Second sino-japanese war in 1940, the IJAAF bombed the city of Ningbo with ceramic bombs full of fleas carrying the bubonic plague. According to Daniel Barenblatt, Prince Tsuneyoshi Takeda received, with Prince Mikasa, a special screening by Shiro Ishii of a film showing imperial planes loading germ bombs for bubonic dessemination over Ningbo in 1940.

By 1941 the Japanese Army Air Force had about 1,500 combat capable aircraft. During the first years of the war, Japan continued technical development and deployment of increasing advanced types of aircraft and enjoyed air superiority over most battlefields due to superior equipment and the combat experience of its crews. However, as the war continued, Japan was unable to maintain volume production of aircraft due to material shortages and the damage to Japan's industrial infrastructure due to Allied bombing of the Japanese home islands. Experienced crews were lost to attrition in combat, and towards the end of its existence, the JAAF was resorted to kamikaze attacks against overwhelmingly superior Allied forces.

World War II Aircraft

Important aircraft used by the Imperial Japanese Army Air Force during the Second Sino-Japanese War and World War II were:

Fighters:

Bombers:

  • Mitsubishi Ki-21 三菱 キ-21 九七式重爆撃機 (Type 97 Heavy Bomber) Sally
  • Mitsubishi Ki-30 三菱 キ-30 九七式軽爆撃機 (Type 97 Light bomber) Ann
  • Kawasaki Ki-32 川崎 キ-32 九八式軽爆撃機, (Type 98 Light bomber) Mary
  • Kawasaki Ki-48 川崎 キ-48 九九式双発軽爆撃機 (Type 99 Twin-engined light bomber) Lily
  • Nakajima Ki-49 中島 キ-49 一〇〇式重爆撃機 呑龍 (Type 100 Heavy bomber "Donryū") Helen
  • Mitsubishi Ki-67 三菱 キ-67 四式重爆撃機 飛龍 (Type 4 Heavy bomber "Hiryū") Peggy

Forward air control aircrafts:

  • Mitsubishi Ki-51 三菱 キ-51 九九式襲撃機/軍偵察機 (Type 99 Assault plane/Reconnaissance plane) Sonia
  • Kawasaki Ki-102 川崎 キ-102 四式襲撃機 (Type 4 Assault plane) Randy

Transports:

  • Nakajima Ki-34 中島 キ-34 九七式輸送機 (Type 97 Transporter) Thora
  • Kawasaki Ki-56 川崎 キ-56 一式貨物輸送機 (Type 1 Cargo aircraft) Thalia
  • Mitsubishi Ki-57 三菱 キ-57 一〇〇式輸送機 (Type 100 Transporter) Topsy
  • Kokusai Ki-59 国際 キ-59 一式輸送機 (Type 1 Transporter) Thersa

Reconnaissance Planes:

  • Mitsubishi Ki-15 三菱 キ-15 九七式司令部偵察機 (Type 97 Army HQ reconnaissance plane) Babs
  • Tachikawa Ki-36 立川 キ-36 九八式直接協同偵察機 (Type 98 Reconnaissance plane) Ida
  • Mitsubishi Ki-46 三菱 キ-49 一〇〇式司令部偵察機 (Type 100 Army HQ reconnaissance plane) Dinah

Trainers:

  • Tachikawa Ki-9 立川 キ-9 九五式一型練習機 (Type 95 Model 1 Intermediate trainer) Spruce
  • Tachikawa Ki-17 立川 キ-17 九五式三型練習機 (Type 95 Model 3 Basic trainer) Cedar
  • Tachikawa Ki-54 立川 キ-54 一式双発高等練習機 (Type 1 Twin-engine advanced trainer) Hickory
  • Tachikawa Ki-55 立川 キ-55 九九式高等練習機 (Type 99 Advanced trainer) Ida
  • Manshū Ki-79 満州 キ-79 二式高等練習機 (Type 2 Advanced trainer)

Other planes:

  • Kokusai Ki-76 国際 キ-76 三式指揮連絡機 (Type 3 Command-control/Liaisonal plane) Stella
  • Kayaba Ka-1 萱場 カ号観測機 (Ka-Gō Artillery-spotter)

Organization

Army Aeronautical Department Sections

  • Commander-in-Chief of Army Air Service Office
  • Air Force Staff Department
  • General Affairs and Administrative Department
  • Inspectorate General of Aviation: General Affairs Unit of Inspectorate of Army Aviation
  • Air Training and Instruction Department
  • Army Air Academy
  • Supply Bureau
  • Tachikawa Army Air Arsenal
  • Army Air Transport Department
  • Army Air Intelligence Department

Operational Organization

Before World War I, the basic unit of the Army Air Service was the Air Battalion (航空大隊, Kōkū Daitai), each consisting of two squadrons (中隊, Chutai) with nine aircraft each, plus three reserve aircraft and three earmarked for use by the headquarters, for a total of 27 aircraft per battalion. The officer commanding the chutai was the Chutaicho, whose rank was usually that of captain. The commander's aircraft often hand distinctive markings, often a partly or totally scarlet, red, orange or yellow tail.

In a reorganization of 1927-05-05, the Air Regiment (飛行連隊, Hikō Rentai) was created, each consisting of two battalions, with each battalion consisting of up to four squadrons. Each Air Regiment was a mixed purpose unit, consisting of a mixture of fighter and reconnaissance squadrons.

With the start of the Second Sino-Japanese War in 1937, operational conditions favored the use of many small units, resulting in the creation of many independent Air Battalions (独立飛行大隊, Dokuritsu Hikō Daitai) or even independent squadrons (独立飛行中隊, Dokuritsu Hikō Chutai), each with its own distinctive markings.

In August 1938, a complete re-organization of the Army Air Service resulted in the creation of the Air Combat Group (飛行戦隊, Hikō Sentai), which replaced all of the former Air Battalions and Air Regiments. Each Air Combat Group was a single-purpose unit consisting typically of three Squadrons, divided into three flights-小隊-shōtai of three aircraft each. Together with reserve aircraft and the headquarters flight, an Air Combat Group typically had 45 aircraft (fighter) or up to 30 aircraft (bomber or reconnaissance). Two or more Air Combat Groups formed an Air Division (飛行団, Hikōdan), which, together with base and support units and a number of Independent Squadrons, formed an Air Corps (飛行集団, Hikō Shudan).

In 1942, the Air Corps were renamed Air Divisions (飛行師団, Hikō Shidan), to mirror the terminology for infantry divisions, but the structure remained the same. Two Air Divisions, together with some independent units made an Air Army (航空軍, Kōkū gun).

Throughout most of the Pacific War, the Japanese Army Air Service was organized into four Air Armies, with two more added in the final stages of the war:

  • 1st Air Army – HQ Tokyo, basing in the Kanto Plain covering the Japanese home islands, Taiwan, Korea and Karafuto.
  • 2nd Air Army - HQ Hsinking, covering Manchukuo
  • 3rd Air Army - HQ Singapore, covering Southeast Asia
  • 4th Air Army - HQ Rabaul, covering the Solomon Islands and New Guinea
  • 5th Air Army - HQ Nanking, covering Japanese-occupied portions of southern and eastern China.
  • 6th Air Army – on Kyūshū covering Taiwan and Okinawa

In April 1944, a reorganization of the Japanese Army Air Service occurred. Maintenance and ground service units, formerly a separate command, were merged into the Air Combat Group (Hiko Sentai). The flying squadrons of the Air Combat Group were re-designated as Attack Units (攻撃隊, Kogekitai), and the ground units were designated Maintenance Units (整備隊, Seibutai).

Other changes in the final stages of the war was the formation of “Special Attack Units” and "Air-shaking Units", which were short-lived units with their own names (often taken from Japanese mythology or history) and markings, but located within existing squadrons. These units were specially designated and trained with the mission of air-to-air ramming of Allied bomber aircraft. They usually had their armaments removed and their airframes reinforced.

In the final phase of the war, the Special Attack Units evolved into dedicated suicide units for kamikaze missions. Around 170 of these units were formed, 57 by the Instructor Air Division alone. Notionally equipped with 12 aircraft each, it eventually comprised around 2000 aircraft.

The final reorganisation of the took place during preparation for Opertation Ketsu-Go, the defence of the home islands in 1945 when all the Air Armies were combined under a centralised command of General Masakau Kawabe .

Special Operations Forces

Teishin Shudan ("Raiding Group") was the IJA's special forces/airborne unit during World War II. The word teishin may be literally translated as "dash forward", and is usually translated as "raiding". It may also be regarded as similar to the "commando" designation in the terminology of other armies. The unit was a division-level force, and was part of the Imperial Japanese Army Air Service (IJAAS). The Teishin units were therefore distinct from the marine parachute units of the Special Naval Landing Forces.

'Giretsu' (義烈空挺隊, Giretsu Kūteitai) was an airborne special forces unit of the Imperial Japanese Army formed from Army paratroopers, in late 1944 as a last-ditch attempt to reduce and delay Allied bombing raids on the Japanese home islands. The Giretsu Special Forces unit was commanded by Lieutenant General Kyoji Tominaga.
Captain Okuyama and Giretsu Airborne unit depart on their mission to Okinawa

Strength

In 1940 the Japanese Army Air Service consisted of the following:

  • 3,000 personnel
  • Over 1,600 aircraft (including 1,375 first line combat aircraft).
  • The aircraft were organized into 85 Squadrons; + 36 fighter + 28 light bomber + 22 medium bomber

Army Air Arsenal

The Japanese Air Army Force had one technical section: the First Tachikawa Air Army Arsenal, which was in charge of aviation research and development. The Arsenal included a testing section for captured Allied aircraft.

The Army Air Arsenal was also connected with Tachikawa Hikoki K.K. and Rikugun Kokukosho K.K. the Army-owned and operationed aircraft manufacturing companies.

Army Escort-Aircraft Carriers

Due to the poor relations between the Imperial Japanese Army and Imperial Japanese Navy, the Army found it necessary to procure and operate their own aircraft carriers for the purposes of providing escort and protection for Army transport shipping convoys. These escort/transport carriers, were converted from small passenger liners or merchant ships. These escort carriers possessed the capacity to operate from eight to 38 aircraft, depending on type and size, and were also used to transport personnel and tanks.

These vessels included the Taiyō Maru, Unyo Maru, Chuyo Maru, Kaiyō Maru, Shinyo Maru, Kamakura Maru, Akitsu Maru, Nigitsu Maru, Kumano Maru, Yamashiro Maru, Chigusa Maru, Shimane Maru, and Otakisan Maru and were operated by civilian crews with Army personnel manning the light and medium anti-aircraft guns.

Uniforms and equipment

As an integral part of the IJA, the Army Air Service wore the standard army uniforms. Only flying personnel and ground crews wore sky blue trim and stripes, while officers wore their ranks on sky blue patches.

Mitsubishi Ki-21 Sally-Gwen Photo Section

Art Hasegawa 1 144 Mitsubishi Ki 21 II Sally 14 Sentai 1944 0A

Art Revell Mitsubishi Ki 21 Sally 0A

Mitsubishi Ki 21 Sally article SAMI 2015 0A

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

Mitsubishi Ki 21 Sally profiles SAMI Mar 2015 0A

Mitsubishi Ki 21 Sally profiles SAMI Mar 2015 0B

Mitsubishi Ki 21 Sally profiles SAMI Mar 2015 0C

Mitsubishi Ki 21 Sally profiles SAMI Mar 2015 0D

Mitsubishi Ki 21 Sally 3d drawing SAMI Mar 2015 0A

Mitsubishi Ki 21 Sally 3d drawing SAMI Mar 2015 0B

Mitsubishi Ki 21 Sally 3d drawing SAMI Mar 2015 0C

Magazine article: Scale Aviation Modeller International Ki-21 Sally Mar 2015

Mitsubishi Ki 21 II Sally 01

Mitsubishi Ki 21 II Sally 14 Sentai 1944 01

Mitsubishi Ki 21 II Sally 14 Sentai 1944 02

Mitsubishi Ki 21 II Sally 14 Sentai 1944 03

Mitsubishi Ki 21 II Sally 60 Sentai 02

Mitsubishi Ki-21 I Sally 01

Mitsubishi Ki-21 I Sally 02

Mitsubishi Ki-21 I Sally 59 Sentai Formosa 1944

Mitsubishi Ki-21 I Sally 60 Sentai 01

Mitsubishi Ki-21 I Sally 60 Sentai China 1941

Mitsubishi Ki-21 I Sally 60 Sentai Manchuria 1939 01

Mitsubishi Ki-21 I Sally 60 Sentai Manchuria 1939 02

Mitsubishi Ki-21 I Sally 60 Sentai on the way to bomb Singapore 01

Mitsubishi Ki-21 I Sally bombing Chungking China 14th Sep 1940 01

Mitsubishi Ki-21 I Sally Daisan Dokuritsu Hikotai Yontan Airfield 25 May 1945

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 01

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 02

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 03

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 04

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 05

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 06

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 07

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 08

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 09

Mitsubishi Ki-21 I Sally Hamamatsu Army Flying School 10

Mitsubishi Ki-21 I Sally on its bomb run 01

Mitsubishi Ki-21 I Sally on its bomb run 02

Mitsubishi Ki 21 Sally 60 Sentai Manchuria 1939 03

Mitsubishi Ki 67 Hiryu Flying Dragon 01

Mitsubishi MC 21 Hiei J BFOA Dai Nippon KOKU 01

USAAF A 20 bombing Nichols Field Philippines 01

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.

Mitsubishi Ki-21 Destroyed on the ground by US Navy fighters at Luzon in the Philippines 1945

Photo: A Japanese Mitsubishi Ki-21 Destroyed on the ground by US Navy fighters at Luzon in the Philippines 1945

 

    Notes:

  1. Francillon 1979, pp. 155–156.
  2. Air International August 1986, pp. 74–75.
  3. Air International August 1986, p. 75.
  4. Francillon 1979, p. 156.
  5. Air International August 1986, pp. 75–76.
  6. Air International August 1986, p. 77.
  7. Francillon 1979, p. 164.
  8. Air International August 1986, pp. 77–78
  9. Francillon 1970, p. 158
  10. Air International August 1986, p. 79
  11. Young 1984, p. 23.
  12. Jowett 2002, p. 20.
  13. Francillon 1970, pp. 160–161
  14. Mondey 1996, p. 208.

    Bibliography:

  • Donald, David (editor). The Encyclopedia of World Aircraft. Prospero Books, 1997. ISBN 1-85605-375-X.
  • Francillon, René J. Japanese Aircraft of the Pacific War. London: Putnam & Company Ltd., 1970. ISBN 0370000331.
  • Francillon, René J. Japanese Aircraft of the Pacific War. London: Putnam, 2nd edition 1979, ISBN 0-370-30251-6.
  • Francillon, René J. The Mitsubishi Ki-21 (Aircraft in Profile number 172). Leatherhead, Surrey, UK: Profile Publications Ltd., 1967.
  • Gunston, Bill. The Illustrated Directory of Fighting Aircraft of World War II. ISBN 0-86101-390-5.
  • Jowett, Philip. The Japanese Army 1931-1945, Volume 2. Botley, Oxfordshire, UK: Osprey Publishing, 2002. ISBN 1-84176-354-3.
  • Lake, Jon. Great Book of Bombers. London: Zenith Press, 2002. ISBN 0-7603-1347-4.
  • Mikesh, Robert and Shorzoe Abe. Japanese Aircraft 1910-1941. Annapolis, MD: Naval Institute Press, 1990. ISBN 1-55750-563-2.
  • Ministry of Defense Japan. Senshi Sosho Volume 36: Rikugun Koku Sakusen(means,Army Air Operation),Okinawa etc. Asagumo Shimbunsha 1970.
  • Mitsubishi Ki-21...Stalwart of the Imperial Army Air Force. Air International, August 1986, Vol 31 No 2. Bromley, UK: Fine Scroll. pp. 74–80, 100—101. ISSN 0306-5634.
  • Mondey, David. The Concise Guide to Axis Aircraft of World War II. London: Chancellor Press, 1996. ISBN 1-85152-966-7.
  • Young, Edward M. "France's Forgotten Air War". Air Enthusiast. Issue 25, August - November 1984. ISSN 0143-5450.
  • Hata, Ikuhiko (2002). Japanese Army Air Force Units and Their Aces: 1931-1945. Grub Street. ISBN 1-902304-89-6.
  • Mayer, S.L. (1976). The Rise and Fall of Imperial Japan. The Military Press. ISBN 0517423138.
  • Sakaida, Henry (1997). Japanese Army Air Force Aces 1937-1945. Osprey Publishing. ISBN 1855325292.
  • Skates John Ray, The Invasion of Japan: Alternative to the Bomb, University of South Carolina Press, 1994

    Magazine References: +

  • Airfix Magazines (English) - http://www.airfix.com/
  • Avions (French) - http://www.aerostories.org/~aerobiblio/rubrique10.html
  • FlyPast (English) - http://www.flypast.com/
  • Flugzeug Publikations GmbH (German) - http://vdmedien.com/flugzeug-publikations-gmbh-hersteller_verlag-vdm-heinz-nickel-33.html
  • Flugzeug Classic (German) - http://www.flugzeugclassic.de/
  • Klassiker (German) - http://shop.flugrevue.de/abo/klassiker-der-luftfahrt
  • Le Fana de L'Aviation (French) - http://boutique.editions-lariviere.fr/site/abonnement-le-fana-de-l-aviation-626-4-6.html
  • Le Fana de L'Aviation (French) - http://www.pdfmagazines.org/tags/Le+Fana+De+L+Aviation/
  • Osprey (English) - http://www.ospreypublishing.com/
  • Revi Magazines (Czech) - http://www.revi.cz/

      Web References: +

  • Wikipedia, the free encyclopedia: https://en.wikipedia.org/wiki/Mitsubishi_Ki-21
  • http://www.aviastar.org/air/japan/mitsubishi_ki-21.php
  • http://www.century-of-flight.net/Aviation%20history/photo_albums/timeline/ww2/Mitsubishi%20Ki%2021%20Sally.htm

This webpage was updated 23rd January 2017