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U.S. Army. Via ibiblio.org
Mitsubishi G4M1 Model 11 "Betty"
|82'0" by 65'8" by 19'9"
25m by 20m by 6m
|Wing area||841 square feet
78 square meters
|266 mph at 13,780 feet
428 km/h at 4200 meters
|196 mph at 9,845 feet
315 km/h at 3000 meters
|21 feet per second
6.4 meters per second
|Two 1530 hp (1141 kW) Mitsubishi MK4A Kasei 11 fourteen-cylinder air-cooled radial engines, driving three bladed metal propellers.|
92 machine gun in the nose
1 7.7mm Type 92 machine gun in the dorsal blister
2 7.7mm Type 92 machine guns in the beam blisters
1 20mm Type 99 Model 1 cannon in the tail.
|One 800 kg (1760 lb) torpedo or up to 800 kg (1760 lbs) of bombs.|
|962 gallons (3640 liters) in the wings.|
|A total of 2,446 G4Ms and G6M1s were built by Mitsubishi
Jukogyo K.K. as follows:
2 12-Shi prototypes (Nagoya plant Sept 1939
and Feb 1940)
| The G4M2 added two flexible nose 7.7mm machine guns and
had a dorsal turret with a 20mm Type 99 Model 1 cannon. It
used Kasei 21 engines driving four bladed metal propellers,
and added doors to the bomb bay. Fuel capacity was increased
to 1714 gallons (6490 liters) and the bomb load was
increased to 1000 kg (2200 lbs).
The G4M2a used 1850 hp (1379 kW) Kasei
25 engines for improved fuel consumption and was fitted
with improved bomb bay doors. It was armed with two nose
7.7mm machine guns and replaced the beam machine guns with
20mm cannon. Some were equipped with Type
6 surface search radar.
Starting with the G4M3, armor and self-sealing
fuel tanks were added at the expense of fuel capacity
(which dropped to 1186 gallons or 4490 liters).
The G4M "Betty" was just coming into service at the time of Pearl Harbor, and it became the backbone of the Japanese land-based naval bomber force. Like its predecessor, the G3M "Nell", it was built for range and speed and sacrificed almost all other qualities. However, it was much better armed than the Nell and had an internal bomb bay (albeit with no doors when loaded with ordnance.) Allied pilots quickly renamed it the One-Shot Lighter for its tendency to catch fire when hit; the Japanese nickname likewise translates roughly as Type 1 Zippo Lighter. The wing was designed as an integral fuel tank with a huge capacity, but it had only rudimentary self-sealing features, and this accounted for the incendiary qualities. Later versions sacrificed range for protection, but losses continued to be high.
The design originated in September 1937 when the Navy
issued a specification to Mitsubishi for a replacement for the
"Nell" with even greater range and speed. This required more than
the 2000 hp available with existing engines, and the design team,
led by Honjo Kiro, chose to use the new Kasei engine. The fuselage
shape was designed for mass production. However, the prototype was
not completed until September 1939 because the design team was
splitting its efforts between the "Betty" and the A6M Zero. Production was
further delayed by an unsuccessful experiment at designing a heavy
escort fighter version of the G4M, the G6M, which ended up being
used as a trainer and transport aircraft.
The original G4M was finally put into production in 1940, with the
first production aircraft coming out of factories in April 1941.
Most of the early production went to French Indochina and Formosa and participated in the
attack on Force Z and the
destruction of American
air power in the Philippines.
The failure of the G5N and G7M bomber projects meant
that the G4M design continued to be refined throughout the war.
Early versions had only rudimentary protection for the fuel tanks,
consisting of rubber sheets on
the bottom of the wing tanks and layers of rubber sheet and sponge
around the fuselage tanks. The G4M3, which did not go into
production until October 1944, included proper self-sealing fuel
tanks and armor around the crew areas. Few were produced.
"Betty" was the plane Yamamoto and his staff were flying in when he was ambushed and killed off Buin in the Solomons.
"Betty" was the mother ship for the Ohka suicide aircraft, but the first Ohka raid lost 16 aircraft before they could get into launch position. This illustrates the continued fragility of "Betty" even with efforts to improve protection with armor and self-sealing fuel tanks.
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