Nell Bomber - Design and Development

Design and Development

The G3M has its origins in a specification submitted to the Mitsubishi company from the Imperial Japanese Navy requesting a heavy bomber aircraft with a range figure unprecedented at the time. This principally stemmed from Admiral Isoroku Yamamoto's influence in the Naval High Commission on the necessity of a 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 the vast far east of the Soviet Union. The requirement for payload was also 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 again also unprecedented, not only in Japanese but also in 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 long distances, but necessarily have 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 powerful offensive armament (in this case in the form of bombs/torpedoes) and 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 guns 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 fighters. Even in the low-speed, low-level role of torpedo bomber, the superior fighter escort - combined with the G3M's high speed - was considered sufficient against any form of ship-based AA guns or carrier-based fighters.

The lightweight structure and complete lack of defensive machine guns and the additional crew necessary to operate them (features in the early prototype design) were considered essential to maintain the speed and high-altitude performance of the G3M with a heavy payload. Even after the modified final prototype, which did include three defensive machine gun emplacements, the G3M kept its lightweight structure and lacked any form of defensive armour or self-sealing fuel tanks, as these were considered to retard speed and altitude. This trait in Japanese bomber/fighter design manifested itself again 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 that its vulnerability to fighters and ground/surface gunfire earned it the unofficial nickname of "one shot lighter" by Allied fighter pilots, and "Hamaki" (" cigar") by its own Japanese crews.

The bombsight used in the G3M was primitive compared to the mechanisms used in the G3M's contemporaries such as the B-24 Liberator and Heinkel He 111. 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, this became a numerical strategy to eliminate the need for singular precision-based bombing.

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 transport versions, G3M-L and L3Y, the latter built by Yokosuka.