Mitsubishi G4M, part three

 

As the war kept going on, bomber designs intended to replace the G4M failed to materialise and Mitsubishi created additional versions to cope with various new roles needed and to eliminate weaknesses in the design, including various engine and weapons.

The first version, the G4M1, suffered some alterations throughout its operational history. In March 1942 new machines were fitted with a supercharger in their Mitsubishi Mk4E 'Kasei' radial engines, in order to improve high altitude performance. These superchargers became standard in August that same year from 406th production aircraft onwards. That same summer, propeller spinners were introduced and in March 1943, aircraft's armour was reinforced though its maximum range and speed was slightly reduced due to the extra weight.

Shortly later, that same spring, the outer half of the tail cone was cut away to improve tail gunner's field of fire. In August, a completely redesigned tail cone was introduced with reduced framing and wide V-shaped cut out. This form of tail cone was standard for every G4M2. In September, individual exhaust stacks were introduced from 954th airframe onwards.

A total of 1.264 G4M1 were manufactured from September 1937 (when the two prototypes were completed) until January 1944 when production of the G4M1 ceased. 

The second version, named G4M2, whose prototype flew for the first time in December 1942, was powered by two Mitsubishi Mk4P 'Kasei' Model 21 engine, rated at 1.775 hp of power driving four-bladed propellers, capable of achieving full feathering function. Main wings were redesigned as well to include LB type laminar flow airfoil and tail horizontal stabilizer area was widened, which improved service ceiling and maximum speed. This version had also larger fuel tanks, which made for longer range. It also featured a new electrically powered tail turret armed with a single 20 mm Type 99 cannon plus a dorsal turret armed with another Type 99 cannon, in lieu of the G4M1's Type 92 7,92 mm machine gun. The remaining posts, nose, waists and cockpit side, were provided each with a single Type 92 machine gun. External differences from the G4M1 included also increased nose glazing, flush side gun positions instead of blisters and rounded wing tips and tail surfaces. These improvements allowed the G4M2 to carry bigger payloads either in bombs or torpedoes. It entered service in July 1943.

Another famous action involving a G4M during World War 2, was the attack that resulted in the death of Admiral Yamamoto. On 18th April 1943 sixteen Lockheed P-38 Lightnings shot down a G4M1 carrying Admiral Yamamoto. In that same battle, another G4M1 carrying Chief of Staff Vice-Admiral Matome Ugaki was also shot down, though Ugaki survived the crash.

The G4M1 was gradually replaced by the G4M2 from June/July 1943 onwards, serving this way in the campaigns of New Guinea, the Solomon Islands and the South Pacific Area, defence of Marianas and, finally in Okinawa. 

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_G4M

2. https://www.valka.cz/Micubisi-G4M1-13-Betty-t31301

3. https://www.valka.cz/Micubisi-G4M1-12-Si-t64994

4. https://www.valka.cz/Micubisi-G4M2-22-Betty-t8550

5. https://www.valka.cz/Micubisi-G4M1-11-Betty-t1284

6. Bunrin Do - Famous Airplanes Of The World 59 - Mitsubishi G4M Betty (translated as much as we could)