the Mistubishi G4M "Betty"
Crew
7
Dimensions
82'0" by 65'8" by 19'9"
25m by 20m by 6m
Wing area 841 square feet
78 square meters
Weights
14,991-20,944 lbs
6800-9500 kg
Maximum speed
266 mph at 13,780 feet
428 km/h at 4200 meters
Cruising speed
196 mph at 9,845 feet
315 km/h at 3000 meters
Climb rate
21 feet per second
6.4 meters per second
Service ceiling
30,000 feet
9100 meters
Power plant
Two 1530 hp (1141 kW) Mitsubishi MK4A Kasei 11 fourteen-cylinder air-cooled radial engines, driving three bladed metal propellers.
Armament
1 7.7mm Type 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.
Bomb load
One 800 kg (1760 lb) torpedo or up to 800 kg (1760 lbs) of bombs.
Maximum range
3749 miles
6000 km
Fuel
962 gallons (3640 liters) in the wings.
Production
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)
30 G6M1 (Nagoya 1940)
1,200 G4M1 (Nagoya Jan 1941-Jan 1944)
1,154 G4M2 (640 at Nagoya and 514 at Okayama, Nov 1942-Aug 1945)
60 G4M3 (Nagoya and Okayama Dec 1943-Aug 1945)
Variants
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).
interesting fact...
In 1933 Admiral Yamamoto convinced the JNAF to adopt a policy of land based long range bombers to engage enemy fleets far out at sea. Three years later the Mitsubishi G3M1a went into service as one of the most advanced long range bombers of any air force in the world. Routine missions in China with a combat radius approximately 1200 miles were flown. Due to heavier then expected Chinese opposition losses were heavy. This led to two consequences, the G3Ms defensive firepower was given a modest upgrade, and far more importantly the G4M program was delayed for one year while a small group of officers insisted on employing the G4M as a ‘Convoy Wing Tip Fighter’. This caused a crucial one year loss of production. In all fairness the USAF’ YB-40 program tried do the same thing and met with as little success as the Japanese did. The Americans’ huge industrial base allowed for a certain leeway in pursuing dead end ideas, and the remote control chin turret was soon included on late model B-17Fs and the follow on B-17G. But the twenty times smaller industrial base of Imperial Japan did not permit the make up of the production deficit.
Admiral Yamamoto’s vision was vindicated on 10 Dec 1941 with the sinking of the HMS Prince of Wales and Repulse. After this it was all down hill for the G4M. To be sure the G4M had its good points, the MK4A Kinsei 1530hp engines compared favorably with the GR-1820 1280hp Wright Cyclone engines having only a slightly inferior performance above twenty five thousand feet. The defensive armament of the ‘Betty’ in its later models became quite formidable with four twenty mm cannons. However its propensity for catching fire was only partially ameliorated, in part because of the lack of two additional engines.
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