MITSUBISHI G3M "NELL"
九六式陸上攻撃機（96しきりくじょうこうげきき）三菱G3Mは大日本帝国海軍（以下海軍とする）の双発爆撃・雷撃機。九六式艦上戦闘機と並んで日本の航空技術が欧米と同等のレベルまで進んだことを示した最初の機体。当時としては驚異的な航続性能を有し、日中戦争から太平洋戦争（大東亜戦争）の初期まで第一線で活躍した。なお海軍の命名法によって急降下爆撃ができない本機は爆撃機ではなく攻撃機とされた。通り名は中攻、後継機は一式陸上攻撃機（通称一式陸攻）。なお、連合軍のコードネームは「Nell 」である。
設計の経緯
ワシントン海軍軍縮条約は加盟国の主力艦(戦艦･巡洋戦艦)の保有量に制限を設けたが、結果として廃艦となる新造主力艦を改造した大型空母の出現を招いた。このことは航空母艦と艦上機を取り込んだドクトリンの複雑化を招き、空母増勢という新しい方面の軍拡を招きかねないことから、ロンドン条約では航空母艦の保有量にも制限がかけられた。しかしながら、いったん出現してしまった空母の存在は｢敵空母による日本本土空襲」の脅威源でありつづけたこともあり、日本海軍では昭和10年(1935)の第二次ロンドン海軍軍縮会議では空母全廃に持ち込もうとして失敗した。
このような経緯の中で日本海軍は、陸上基地から発進して敵艦船(主として敵空母)を攻撃できる「沿岸用攻撃機」の装備を図った。
この当時、海軍機メーカーの中で大型全金属機の製作能力をもっていたのは広廠と三菱であったため、まず広廠で「七試特攻」（「七空攻撃機」とも呼称される。後の九五式陸上攻撃機）の開発に着手し、次いで三菱に「八試特偵」1機の試作が発注された。八試特偵は昭和9年に計画が変更され7.7ミリ機銃二挺を搭載する「八試陸上攻撃機」へと改称された。さらにこの試作の成果を元に九試陸上攻撃機が計画され、三菱内燃機株式会社名古屋航空機製作所に発注された。設計主務者は八試特偵と同じ本庄季郎技師。九六式陸上攻撃機として兵器採用された。
大型陸攻である広廠九五式陸攻が「大攻」、中型の九六式陸攻は｢中攻」とみなされた。
技術の特徴
長距離攻撃機として、空気抵抗削減と燃費削減に重点を置いて設計された。
* 金星エンジンの採用：金星エンジンは、アメリカのプラットアンドホイットニー社よりライセンス生産権を買収した。
* 引き込み式主脚：日本軍用機での採用第1号、飛行時の空気抵抗を大幅に削減する。
* 沈頭鋲の全面採用：同上（採用は九六式艦上戦闘機と同時）
金属板の締結に使われる鋲は、通常 金属板表面に丸い頭が出っ張る。高速で飛ぶ航空機では これが重大な空気抵抗の原因となるので、頭の出ない特殊な沈頭鋲を使用した。この結果 機体表面は非常に平滑に仕上がった。
* 自動操縦装置と方向探知機
* 可変ピッチプロペラ：ハミルトン・スタンダード製。低速時と高速時でプロペラのピッチ（羽取り付け角）を変え、プロペラ推進効率を最適化する装置。
なお 胴体をスマートな形にしたため機内に爆弾倉を設けることができず、爆弾や魚雷は胴体下に吊り下げられた。また爆撃機特有の機首ガラス張り窓を廃したため、前下方の防御火力がゼロとなった。
活躍
日中戦争では航続性能を生かして、設計本来の目的ではない戦略爆撃に使用された。まず九州の基地を発進して、東シナ海を越えて、中華民国本土を爆撃して帰還した。これは渡洋爆撃として国内に大きく宣伝された。その後基地を中国沿岸部に移し、そこから中国奥地の重慶等の都市を爆撃した。この頃から敵地上空で敵戦闘機による損害が増え始め、護衛戦闘機の必要性が真剣に検討され、後の零式艦上戦闘機の誕生につながった。
太平洋戦争では、開戦当日から連日 台湾を発進してフィリピンのアメリカ軍飛行場を爆撃し、短期間にアメリカの航空戦力を壊滅させた。さらに12月10日のマレー沖海戦では、一式陸上攻撃機と協同でイギリス戦艦プリンス・オブ・ウェールズと巡洋戦艦レパルスを撃沈し、戦艦に対する航空優位を決定付けた。
その後は第一線の戦闘を後継機に譲り、輸送などの後方任務につくことが多かった。
派生型
八試特偵（G1M1）
九六陸攻の基になった機体、水冷Ｗ型12気筒九一式500馬力発動機を搭載、わが国初の自動操縦装置と引き込み脚を装備していた、最高速度 266km/h、航続距離2,346km～4,408km。後に発動機を950馬力の震天に換装し最高速度が293km/hに向上した。
1機生産
九試中型陸上攻撃機（甲案型）
八試特偵を基にして尾翼胴体を再設計し操縦席が正副並列式に改められ、銃座と魚雷・爆弾搭載装置が搭載された陸攻型、偵察席が操縦席後方にある。1.2.5.6号機は91式水冷680馬力を装備し、3.4号機は空冷｢金星｣二型680馬力を装備している。
6機生産
九試中型陸上攻撃機（丙案型）
偵察員席が操縦席より前に配置され、機首に透明銃座を設けた、7～10号機 12～21号機の発動機は｢金星｣二型もしくは三型を装備。
15機生産
九六式陸上攻撃機一一型(G3M1)
甲案型を採用し、金星三型、三翅可変ピッチプロペラ装備。
34機生産
九六式陸上攻撃二一型(G3M2)
発動機を金星四二型に換装しプロペラ直径を3.20mに変更したもの。
九六式陸上攻撃二二型(G3M2)
戦訓を取り入れた武装強化型で、胴体上面の後方銃座をブリスター型銃座の20mm旋回砲1門に改め、胴体側面に7.7mm旋回銃各一丁を装備したブリスター型銃座が新設された武装強化型、胴体下方の垂下筒は廃止され、411号機以降は胴体下面の段がなくなり、胴体下面に下方銃の支基が設けられた、武装強化に伴い乗員が7名に増えている。後期生産型の79機は金星四五型を装備している。
238機生産
九六式陸上攻撃二二型(G3M3)
金星五一型装備の最終生産型で全機中島飛行機で生産された。
412機生産
The bomber had a crew of five, and had its first flight in July 1935. The aircraft was armed with three 7.7mm machine guns. Maximum
speed was 188 knots and had a range of over 2,200 miles. The G3M was also designed to carry an 800 kg torpedo for ship attacks.
The G3M has its origins in a specification submitted to the Mitsubishi company from the Imperial Japanese Navy requesting a heavy bomber aircraft with chiefly a range figure unprecedented at the time. This stemmed from principally Admiral Yamamoto's influence in the Naval High Commission of the necessity of a long range heavy bomber capable of encompassing the enormous ranges of the arenas where Imperial Japan sought to conquer in the years to come, including those outlined in the expansionist Tanaka Memorial -- namely China, Southeast Asia, the Pacific Isles and vast Far East Russia. The requirement for payload too, was unprecedented in Japanese military aviation history, though necessary to accommodate the aerial torpedo envisaged to combat the armoured battleships of the Allies in the geographical broadness of the Pacific front. The speed requirement submitted by the Naval Department was also unprecedented in not only Japanese but also international heavy bomber aviation, where in relation to the envisaged Japanese battlegrounds of China and the Pacific, the bomber would need to not only cover lengthy range, but necessarily feature the exceptional speed to strike distant targets with a minimum attack time. Thus the G3M was an embodiment of Japanese military aircraft design in the brief period leading to the Pacific War, with great offensive armament (in this case in the form of bombs/torpedoes), range and speed emphasised over protection and defensive capabilities.
In terms of the latter, the G3M was originally designed as a model without any form of defensive weaponry or machine guns, but purely as a bomber craft, with its high-altitude performance being regarded sufficient to evade enemy anti-aircraft fire and its high speed in combination with the planned high performance Mitsubishi A5M fighter envisaged as an armed escort being considered sufficient to counter any form of enemy fighter interdiction. Even in the low-range, close support role of anti-shipping torpedo bombing, the envisagement of superior fighter escort, combined with the G3M's high speed was considered sufficient against any form of ship-based fire or carrier-based fighter interception.
The light-weight structure and complete lack of defensive machine guns and thus the additional crew necessary to operate them (features in the early prototype design) were naturally considered essential to maintain the speed and high altitude performance of the G3M with a heavy payload. Even after the modified final prototype, which included defensive machine gun emplacements, the G3M kept its light-weight structure and lacked any form of defensive armour or heavier self-sealing fuel tanks as these were considered to retard speed and altitude. This trait in Japanese bomber/fighter design manifested in its successor, the G4M, which was so heavily designed to accommodate fuel and bombing armament for long range strikes at the expense of defence, its vulnerability to armed interdiction and fire earned it its unofficial nickname as the 'one shot lighter' to Allied fighter pilots, and 'Hamaki', or '(flying) cigar' to its own Japanese crews.
The bomb aiming sight used in the G3M was primitive compared to the mechanisms used in the G3M's contemporaries such as the B-24 and Heinkel He 111, indeed, aside from the limited precision necessary in its naval role as a long range torpedo bomber against Allied naval fleets, the G3M frequently operated with other G3M units in massive 'wave' formations, thus this became a numerical strategy to eliminate the opposed need for singular precision-based bombing, this alternative tactic resulting in horrendous damage and death figures to civilians and civilian population centres from the aerial bombing campaigns against metropolitan targets in China and the Allied Asia-Pacific region.
Later the Nakajima Company redesigned the G3M into the improved G3M3 (Model 23) with more powerful engines and increased fuel capacity. This version was only manufactured by Nakajima, being the most rapidly produced in wartime. This version entered service in 1941, and was maintained in service for two years, and later used in 1943 alongside the G3M2s for long-range maritime reconnaissance with radar due to its excellent long range performance. Other G3M derivations were the transports G3M-L and L3Y, used for transport duties.
[edit] Operational history
The G3M flew for first time in 1935, taking off from a Nagasaki airfield belonging to Mitsubishi Heavy Industries and landing at Haneda Airport on the outskirts of Tokyo. The G3M first saw combat in Japan's expansionist campaigns on the Chinese mainland in what became known as the Second Sino-Japanese War, where as part of a pre-emptive strike plan designed by Admiral Yamamoto (the very authority that had demanded the designing of such a bomber), the G3M was able to exploit its long range capability, departing from bases in Formosa, Kyūshū and Jeju Island effectively crossing the East China Sea and terror bombing coastal and inland targets in China, including the infamously treacherous bombing of the Battle of Shanghai and Nanjing. Thus while it was the first transoceanic bomber in air war history, it also had the dubious distinction of being the first mass-produced bomber aircraft to wage terror bombing indiscriminately on civilians. Later, from bases in occupied Chinese territories, it took part in the strategic carpet bombing of the Chinese heartland, its combat range being sufficient to cover the elongated distances involved. Most notably, it was involved in the round-the-clock Bombing of Chongqing, a campaign that resulted in what would now be considered massive collateral damage. When the Pacific War erupted in 1941 after a similarly Japanese-style pre-emptive strike in the Bombing of Pearl Harbor, although antiquated, 200 first line units were operated in the central Pacific and the Philippines. On the 8th of December 1941, (7th across the International Date Line), G3Ms struck Singapore City from bases in occupied Vietnam as one of many air raids during the Battle of Singapore, resulting in thousands of British and Asiatic civilians dead. Wake Island was similarly bombed by G3Ms on the first day of the war, with both civilian and US Navy infrastructure being heavily damaged on the ground.
The G3M was famous for taking part of the sinking of Prince of Wales and Repulse with the more advanced Mitsubishi G4M "Betty", on 10 December 1941. "Nells" provided important support during the attack on the HMS Prince of Wales and HMS Repulse (Force Z) near the Malayan coast. The Prince of Wales and the Repulse were the first two battleships ships ever sunk exclusively by air attack while at sea during war.
From 1943, the majority of "Nells" served as glider tugs, aircrew and paratroop trainers and for transporting high-ranking officers and VIPs between metropolitan islands, occupied territories and combat fronts until the end of the war.
[edit] Variants
Ka-15
Prototype with either Hiro Type 91 (750 hp), Mitsubishi Kinsei 2 (830 hp), or Mitsubishi Kinsei 3 (910 hp) engines and glass or solid nose, 21 built.
G3M1a/c
Redesignated prototypes powered by Hiro Type 91 or Mitsubishi Kinsei engines, glass nose.
G3M1 Model 11
Land-based attack bomber Navy Type 96 first series model. Major extension of the cabin with a revised cover, some with fixed pitch propeller, 34 built.
G3M1-L
G3M1 converted into an armed or unarmed military transport version and powered by Mitsubishi Kinsei 45 (1,075 hp) engines.
G3M2 Model 21
More powerful engines and increased fuel capacity, dorsal turret. 343 constructed by Mitsubishi, 412 G3M2 and G3M3 manufactured by Nakajima.
G3M2 Model 22
Upper and belly turrets substituted for one upper turret, glass side positions, 238 built.
G3M3 Model 23
More powerful engines and increased fuel capacity for longer range, constructed by Nakajima.
L3Y1 Model 11
Transport Navy Type 96, advanced conversion of G3M1 armed transport.
L3Y2 Model 12
Modification of G3M2 with Mitsubishi Kinsei engines.
General characteristics
* Crew: 7
* Length: 16.45 m (53 ft 11½ in)
* Wingspan: 25 m (82 ft 0 in)
* Height: 3.68 m (12 ft ⅞in)
* Wing area: 75 m² (807 ft²)
* Empty weight: 4,965 kg (10,923 lb)
* Loaded weight: 8,000 kg (17,600 lb)
* Powerplant: 2× Mitsubishi Kinsei 45 radial engine, 1,075 hp (791 kW) each
Performance
* Maximum speed: 375 km/h (203 knots, 233 mph)
* Cruise speed: 280 km/h (151 knots, 174 mph)
* Range: 4,400 km (2,730 mi)
* Service ceiling 9,200 m (30,200 ft)
* Rate of climb: 6 m/s (1180 ft/min)
Armament
* Guns
o 1 x Type 99 20mm cannon in rear dorsal turret
o 4 x Type 92 7.7 mm machine gun in cockpit, left and right side positions, and in retractable forward dorsal turret.
* Bombs
o 800 kg of bombs or 1 torpedo
SEE THE G3M IN ACTION VIDEO
The G3M has its origins in a specification submitted to the Mitsubishi company from the Imperial Japanese Navy requesting a heavy bomber aircraft with chiefly a range figure unprecedented at the time. This stemmed from principally Admiral Yamamoto's influence in the Naval High Commission of the necessity of a long range heavy bomber capable of encompassing the enormous ranges of the arenas where Imperial Japan sought to conquer in the years to come, including those outlined in the expansionist Tanaka Memorial -- namely China, Southeast Asia, the Pacific Isles and vast Far East Russia. The requirement for payload too, was unprecedented in Japanese military aviation history, though necessary to accommodate the aerial torpedo envisaged to combat the armoured battleships of the Allies in the geographical broadness of the Pacific front. The speed requirement submitted by the Naval Department was also unprecedented in not only Japanese but also international heavy bomber aviation, where in relation to the envisaged Japanese battlegrounds of China and the Pacific, the bomber would need to not only cover lengthy range, but necessarily feature the exceptional speed to strike distant targets with a minimum attack time. Thus the G3M was an embodiment of Japanese military aircraft design in the brief period leading to the Pacific War, with great offensive armament (in this case in the form of bombs/torpedoes), range and speed emphasised over protection and defensive capabilities.
In terms of the latter, the G3M was originally designed as a model without any form of defensive weaponry or machine guns, but purely as a bomber craft, with its high-altitude performance being regarded sufficient to evade enemy anti-aircraft fire and its high speed in combination with the planned high performance Mitsubishi A5M fighter envisaged as an armed escort being considered sufficient to counter any form of enemy fighter interdiction. Even in the low-range, close support role of anti-shipping torpedo bombing, the envisagement of superior fighter escort, combined with the G3M's high speed was considered sufficient against any form of ship-based fire or carrier-based fighter interception.
The light-weight structure and complete lack of defensive machine guns and thus the additional crew necessary to operate them (features in the early prototype design) were naturally considered essential to maintain the speed and high altitude performance of the G3M with a heavy payload. Even after the modified final prototype, which included defensive machine gun emplacements, the G3M kept its light-weight structure and lacked any form of defensive armour or heavier self-sealing fuel tanks as these were considered to retard speed and altitude. This trait in Japanese bomber/fighter design manifested in its successor, the G4M, which was so heavily designed to accommodate fuel and bombing armament for long range strikes at the expense of defence, its vulnerability to armed interdiction and fire earned it its unofficial nickname as the 'one shot lighter' to Allied fighter pilots, and 'Hamaki', or '(flying) cigar' to its own Japanese crews.
The bomb aiming sight used in the G3M was primitive compared to the mechanisms used in the G3M's contemporaries such as the B-24 and Heinkel He 111, indeed, aside from the limited precision necessary in its naval role as a long range torpedo bomber against Allied naval fleets, the G3M frequently operated with other G3M units in massive 'wave' formations, thus this became a numerical strategy to eliminate the opposed need for singular precision-based bombing, this alternative tactic resulting in horrendous damage and death figures to civilians and civilian population centres from the aerial bombing campaigns against metropolitan targets in China and the Allied Asia-Pacific region.
Later the Nakajima Company redesigned the G3M into the improved G3M3 (Model 23) with more powerful engines and increased fuel capacity. This version was only manufactured by Nakajima, being the most rapidly produced in wartime. This version entered service in 1941, and was maintained in service for two years, and later used in 1943 alongside the G3M2s for long-range maritime reconnaissance with radar due to its excellent long range performance. Other G3M derivations were the transports G3M-L and L3Y, used for transport duties.
[edit] Operational history
The G3M flew for first time in 1935, taking off from a Nagasaki airfield belonging to Mitsubishi Heavy Industries and landing at Haneda Airport on the outskirts of Tokyo. The G3M first saw combat in Japan's expansionist campaigns on the Chinese mainland in what became known as the Second Sino-Japanese War, where as part of a pre-emptive strike plan designed by Admiral Yamamoto (the very authority that had demanded the designing of such a bomber), the G3M was able to exploit its long range capability, departing from bases in Formosa, Kyūshū and Jeju Island effectively crossing the East China Sea and terror bombing coastal and inland targets in China, including the infamously treacherous bombing of the Battle of Shanghai and Nanjing. Thus while it was the first transoceanic bomber in air war history, it also had the dubious distinction of being the first mass-produced bomber aircraft to wage terror bombing indiscriminately on civilians. Later, from bases in occupied Chinese territories, it took part in the strategic carpet bombing of the Chinese heartland, its combat range being sufficient to cover the elongated distances involved. Most notably, it was involved in the round-the-clock Bombing of Chongqing, a campaign that resulted in what would now be considered massive collateral damage. When the Pacific War erupted in 1941 after a similarly Japanese-style pre-emptive strike in the Bombing of Pearl Harbor, although antiquated, 200 first line units were operated in the central Pacific and the Philippines. On the 8th of December 1941, (7th across the International Date Line), G3Ms struck Singapore City from bases in occupied Vietnam as one of many air raids during the Battle of Singapore, resulting in thousands of British and Asiatic civilians dead. Wake Island was similarly bombed by G3Ms on the first day of the war, with both civilian and US Navy infrastructure being heavily damaged on the ground.
The G3M was famous for taking part of the sinking of Prince of Wales and Repulse with the more advanced Mitsubishi G4M "Betty", on 10 December 1941. "Nells" provided important support during the attack on the HMS Prince of Wales and HMS Repulse (Force Z) near the Malayan coast. The Prince of Wales and the Repulse were the first two battleships ships ever sunk exclusively by air attack while at sea during war.
From 1943, the majority of "Nells" served as glider tugs, aircrew and paratroop trainers and for transporting high-ranking officers and VIPs between metropolitan islands, occupied territories and combat fronts until the end of the war.
[edit] Variants
Ka-15
Prototype with either Hiro Type 91 (750 hp), Mitsubishi Kinsei 2 (830 hp), or Mitsubishi Kinsei 3 (910 hp) engines and glass or solid nose, 21 built.
G3M1a/c
Redesignated prototypes powered by Hiro Type 91 or Mitsubishi Kinsei engines, glass nose.
G3M1 Model 11
Land-based attack bomber Navy Type 96 first series model. Major extension of the cabin with a revised cover, some with fixed pitch propeller, 34 built.
G3M1-L
G3M1 converted into an armed or unarmed military transport version and powered by Mitsubishi Kinsei 45 (1,075 hp) engines.
G3M2 Model 21
More powerful engines and increased fuel capacity, dorsal turret. 343 constructed by Mitsubishi, 412 G3M2 and G3M3 manufactured by Nakajima.
G3M2 Model 22
Upper and belly turrets substituted for one upper turret, glass side positions, 238 built.
G3M3 Model 23
More powerful engines and increased fuel capacity for longer range, constructed by Nakajima.
L3Y1 Model 11
Transport Navy Type 96, advanced conversion of G3M1 armed transport.
L3Y2 Model 12
Modification of G3M2 with Mitsubishi Kinsei engines.
General characteristics
* Crew: 7
* Length: 16.45 m (53 ft 11½ in)
* Wingspan: 25 m (82 ft 0 in)
* Height: 3.68 m (12 ft ⅞in)
* Wing area: 75 m² (807 ft²)
* Empty weight: 4,965 kg (10,923 lb)
* Loaded weight: 8,000 kg (17,600 lb)
* Powerplant: 2× Mitsubishi Kinsei 45 radial engine, 1,075 hp (791 kW) each
Performance
* Maximum speed: 375 km/h (203 knots, 233 mph)
* Cruise speed: 280 km/h (151 knots, 174 mph)
* Range: 4,400 km (2,730 mi)
* Service ceiling 9,200 m (30,200 ft)
* Rate of climb: 6 m/s (1180 ft/min)
Armament
* Guns
o 1 x Type 99 20mm cannon in rear dorsal turret
o 4 x Type 92 7.7 mm machine gun in cockpit, left and right side positions, and in retractable forward dorsal turret.
* Bombs
o 800 kg of bombs or 1 torpedo
SEE THE G3M IN ACTION VIDEO