Mitsubishi G4M

Mitsubishi G4M
Mitsubishi G4M1 of 801st Kōkūtai
Role	Medium bomber
Manufacturer	Mitsubishi
Designer	Kiro Honjo
First flight	1940
Introduction	June 1941
Retired	1945
Primary user	Imperial Japanese Navy Air Service
Number built	2,435

The Mitsubishi G4M (long designation: Mitsubishi Navy Type 1 attack bomber: 一式陸上攻撃機, 一式陸攻 Isshiki rikujō kōgeki ki, Isshikirikkō) was the main twin-engine, land-based bomber used by the Imperial Japanese Navy Air Service in World War II. The Allies gave the G4M the reporting name Betty. Japanese Navy pilots called it "葉巻" "hamaki" ("cigar", literally "leaf roll"), due to its cylindrical shape.

The G4M had very good performance, especially range, which was achieved by its structural lightness and an almost total lack of protection for its crew, with no armor plating or self-sealing fuel tanks. These omissions proved to be its weakness when confronted with American fighter aircraft during the Pacific War.

The G4M was designed for a long range and high speed at the time of its introduction. Consequently, several weight-saving measures were incorporated into the design, such as dispensing with self-sealing fuel tanks and armor, which caused Allied fighter pilots to give it derisive nicknames such as "the one-shot lighter", "the flying Zippo" and "the flying cigar" because of their tendency to explode or catch on fire from any slight damage to the wing fuel tanks after being hit by aerial machine gun fire or ground-based anti-aircraft fire. Similarly, pilots of the Imperial Japanese Navy despairingly called the G4M the "type one lighter", the "flying lighter" and the "hamaki" ("cigar"). This was partially due to the fact that on many occasions, the G4M was used for low-altitude torpedo attacks on ships during which their performance advantages were negated. The G4M was frequently shot down by anti-aircraft artillery fire, and even by small arms. The G4M's relatively large size made it an easy gunnery target, and the predictable approach path required for a torpedo run made for a generally easy interception by Allied fighter aircraft.

When used for medium- to high-altitude bombing against stationary land targets like supply depots, seaports or airfields, it was much harder to intercept. Using its long range and high speed, the G4M could appear from any direction, and then it could be gone before any fighters intercepted them. The 20 mm cannon in its tail turret was much heavier armament than was commonly carried by bombers of either side, making aerial attacks from the rear quite dangerous for the Allied fighter aircraft. Sometimes, assuming they did not catch fire after being hit in the wings by flak from the ground or by machine gun bullets from enemy fighters, G4Ms also proved to be able to remain airborne despite being badly damaged. For example, after the attack of the 751 Kōkūtai (air group) on the USS Chicago (CA-29) during the Battle of Rennell Island, three out of four surviving aircraft (of the original eleven) returned despite flying with only one engine.

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Wikipedia