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  • Mitsubishi G4M (Betty) Land-Based Medium Navy Bomber Aircraft

    The Mitsubishi G4M Betty will forever be linked to the ill-fated flight which saw the death of Japanese Admiral Yamamoto at the hands of American Lockheed P-38 Lightning fighters over Bougainville in 1943.

     Updated: 1/3/2017; Authored By Staff Writer; Content ¬©www.MilitaryFactory.com

    Like most of Imperial Japan's aircraft in the early stages of World War 2, the Mitsubishi G4M (codenamed "Betty" by the Allies) was a potent performer in operation as a land-based naval bomber. The system was of a strong design and featured impressive range for the time and would see combat action throughout the entire war. Though appearing in limited numbers, the G4M - at least for a time - was a weapon to be reckoned with. Despite its wartime success, the type is universally remembered as one of two "Betty" aircraft downed by a pair of American P-38 Lightnings and with it, Japanese Admiral Isoroku Yamamoto - mastermind of the Pearl Harbor attack - a disastrous blow to Imperial Japanese operations in the Pacific Theater. The P-38 pilots the day of April 18, 1943 were 1st Lt. Rex T. Barber and Captain Thomas G. Lamphier intercepting from Henderson Field, Guadalcanal.

    The G4M started as a product of the Mitsubishi company, charged with filling the 1937 requirement calling for a capable long-range bomber aircraft. The system first flew in mid-October of 1939 and did not disappoint - proving the design capable of possessing both above average speed and range. Defensive armament consisted of a combination of cannon and machine guns. 2 x 7.7mm machine guns were positioned in the nose and two side blisters (one gun per blister). A single cannon was placed in the dorsal turret and in the tail gun position. Crew accommodations amounted to seven personnel and an internal bomb load of up to 2,205 pounds was afforded. With this design being of naval origins, the Betty was also slated to carry up to 1 x 1,764 anti-ship torpedo in place of the traditional bomb load.

    By any regard, the Japanese Navy had found itself a capable performer and the G4M began to prove its worth in early entanglements that included the sinking of the British warships HMS Repulse and the HMS Prince of Wales, both occurring in the first year of the aircrafts service. In addition to successful action against the Allies, the G4M was also seen in combat against China.

    If the G4M "Betty" contained any weakness in its design, it was a weakness that was common among many of the Japanese aircraft of the Second World War. Protection in the way of additional armor given to the crew and the fuel tanks were usually sub-standard when compared to its contemporaries. As such, the system proved to be highly susceptible to Allied gunfire with relative ease. Any sort of dominance that the G4M exhibited in the opening years of the conflict were soon reversed as the newer and better Allied fighters were made available in any kind of concentrated number across the Pacific. The days of the G4M were numbered from then on, despite seeing operational service through to the end of the war. The system was fielded in a few variants, each seen as a general improvement over the previous marks. Total production amounted to only a few thousand examples.

    Note the whole number dimensions of the aircraft design (in meters).

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    Mitsubishi G4M2 (Betty) Technical Specifications

    Service Year: 1941
    Type: Land-Based Medium Navy Bomber Aircraft
    National Origin: Imperial Japan
    Manufacturer(s): Mitsubishi - Japan
    Production Total: 2,414

    Structural (Crew Space, Dimensions and Weights)

    Operating Crew: 7
    Length: 65.62 feet (20 meters)
    Width: 82.02 feet (25.00 meters)
    Height: 19.69 feet (6.00 meters)

    Weight (Empty): 17,990 lb (8,160 kg)
    Weight (MTOW): 27,558 lb (12,500 kg)

    Installed Power and Standard Day Performance

    Engine(s): 2 x Mitsubishi MK4P Kasei 21 radial piston engine developing 1,800 horsepower each.

    Maximum Speed: 272 mph (438 kph; 237 knots)
    Maximum Range: 3,765 miles (6,059 km)
    Service Ceiling: 29,364 feet (8,950 meters; 5.56 miles)
    Rate-of-Climb: 810 feet-per-minute (247 m/min)

    Armament / Mission Payload

    2 x 7.7mm Type 92 machine guns in nose
    1 x 20mm Type 99 cannon in dorsal turret
    1 x 20mm Type 99 cannon in tail gun position
    2 x 7.7mm Type 92 machine guns in side blister positions (one gun per side)

    Maximum internal bomb loadout of up to 2,205lbs OR 1 x 1,764lb torpedo in place of bombs for anti-shipping duties.

    Global Operators / Customers

    Imperial Japan

    Model Variants (Including Prototypes)

    G4M1 - Prototype Model Designation; first flight October 23, 1939; produced in variant Model 11 and Model 22 detailed below; 1,200 examples produced.

    Navy Type 1 Attack Bomber Model 11 - Initial Production Models.

    Navy Type 1 Attack Bomber Model 22 - Second Production Models featuring revised engines.

    G4M2 - "Improved" G4M1 Models; produced in variant Model 22A and Model 22B detailed below; 1,154 examples produced.

    Navy Type 1 Attack Bomber Model 22A - Featured Mitsubishi Kasei radial engines of 1,800 horsepower; defensive armament revised along with increased fuel capacity.

    Navy Type 2 Attack Bomber Model 22B - Similar to Model 22A.

    Navy Type 1 Attack Bomber Model 24 - "Improved" G4M2.

    G4M3 - "Improved" G4M2 Models

    Navy Type 1 Attack Bomber Model 34 (G4M3); 60 examples produced.