The G4M was the principle Imperial Japanese Navy medium bomber of
the war, operated from land bases. It originated in a 1937 request for
a bomber with a longer range and higher speed than the G3M. To meet
this requirements, weight had to be shaved and this meant no armor
protection for the fuel tanks or crew. The unprotected large wing tanks
in particular proved to be vulnerable, resulting in many encounters
with Allied fighters turning the Betty into a flaming coffin. Also,
after 1942, as the Japanese were forced on the defensive, the long
range of the G4M became less and less of an advantage.
However, early in the war the G4M gave valuable service. It
participated in the sinking of the HMS Prince of Wales and Repulse in December 1941, as well
as the first air raid on Darwin, Australia. Some 1,150 of the G4M2 were
built.
An additional 420 gallons of fuel could be carried in place of the
bomb load. A 1,764-lb torpedo could be carried externally instead of a
bomb load.
The G4M2 has a crew of seven: Pilot, co-pilot, navigator (who also
acts as bombardier and operates the two forward Type 92's), radio
operator (who also mans the dorsal turret) and three gunners (two wasit
positions and the tail). The G4M2 uses 134 gallons of aviation fuel per
hour at routine
usage.
Subassemblies: Heavy Fighter-Bomber chassis +4, Light
Bomber
Wings +4, 2xSmall AFV Engine Pods +2, full rotation Medium Weapon
turret +1, three retractable wheels +1.
Powertrain: 2x1,341-kW aerial HP supercharged gasoline
engines [Pods] with 2x1,341-kW props, and 1,294-gallon standard
fuel tanks [Body and Wings], 4,000-kw batteries
Occupancy: 7 CS Cargo: 19 Body.
Armor
All: 2/3
Weaponry
2xAircraft LMG/Type 92 [Body:F] (1,164 each)
Aircraft LMG/Type 92 [Body:L] (1,164)
Aircraft LMG/Type 92 [Body:R] (1,164)
20mm Short Aircraft AC/Type 99-1 [Turret::F] (125)
20mm Short Aircraft AC/Type 99-1 [Body:B] (125).
10x220-lb bombs [Body:U].
Equipment
Body: Large radio receiver and transmitter, navigation
instruments,
autopilot., bombsight, 2,200-lb bomb bay.
Statistics
| Size: 65'x82'x20' | Payload: 6.1 tons | Lwt: 13.8 tons |
| Volume: 448 |
Maint.: 21 hours | Price: $90,200 |
HT: 8.
HP: 525 [body], 300 [each wing], 150 [each pod], 50 [each wheel]
| aSpeed: 272 |
aAccel: 6 |
aDecel: 16 |
aMR: 3.75 |
aSR: 2 |
Stall: 79 |
Design Notes
Design speed was 299 mph. The historical speed has been used, as well
as the actual wing area (841 square feet). To better match historical
weight, wing cost, weight and HPs were divided by 2. In the end, loaded
weight was increased by only 2%
The G4M1 Model 11 (1941) lacked a dorsal turret, having a blister
instead. The dorsal position was armed with only single 7.7mm Type 92
MG. They reached 266 mph powered by unsupercharged 1,140-kW engines.
Bombload was only 1,800 lbs. Some 400 were built. The Model 12 (1942)
added superchargers, for better high altitude performance. Some 770
were built. In 1943, DR 10 armor was added to the underside of the wing
tanks and the rear gunner position, which reduced top speed by 6 mph.
The G4M2 Model 22A Ko replaced the waist 7.7mm Type 92's with 20mm
Type 99-1's.
The G4M2 Model 22B Otsu had more powerful Type 99-2 (20mm Medium
Aircraft ACs) in all four cannon positions.