- Yes
- No
Anyone knowledgeable about WWII aircraft has certainly heard of self-sealing fuel tanks. To put it simple, they are rubber tanks, which seal the bullet holes to prevent fuel leaking out in highly flammable aerosol form. As aircraft guns got heavier and more numerous, the self-sealing tanks also had to get sturdier and heavier, but against heavy damage even that just wasn’t enough. For that reason Japanese began to use CO₂= carbon dioxide fire extinguishers to better protect their aircraft.
CO₂ fire extinguishing system installed in N1K2-J.
In Japan this appears to have become almost a standard feature for new frontline fighter and bomber variants around mid 1944. In case of certain variants of A6M, D4Y and B6N, it was used as their only fuel tank protection without self-sealing tanks and appears to have been quite lacking alone. In fact, with none self-sealing tanks the system’s intention wasn’t even to save the aircraft itself, but rather provide enough time for the crew to ditch before the fire would turn into catastrophic explosion. For late A6Ms in specific, only the wing tanks had this system, which is why the front fuselage tank was left empty in some flightgroups.
Most other aircraft with this system came with self-sealing fuel tanks and they could save the whole plane. For example pilots from both sides recognized how N1K2-J and late Ki-61 did not explode if ignited as they could put out the fire very quicky. Even with good reliability and efficiency, the system wasn’t necessarily as good solution as even stronger self-sealing tanks as it could only extinguish each tank or couple of linked tanks once. It also wouldn’t aid at sealing the tank, meaning it could continue to leak fuel. It could be said system was at it’s best with aircraft which already had otherwise strong protection.
An interesting exception were Mitsubishi J2M and A7M. Their fuselage tanks had possibly the thickest coating in single seat fighters of their time (30mm), while their wing tanks had no self-sealing protection at all and thus relied solely on the CO₂ extinguishers. This was because in IJN’s perspective the wing tank capacity would drop too much if they were self-sealing. After all the wing tanks had to be fitted inside rather flat wing structure where couple of centimetres meant a lot and Japanese self-sealing fuel tanks were somewhat bulkier than allied types of comparative effectiveness.
An Allied report about a captured J2M2. Early on this system was manually operated, but later an automatic thermostat trigger was used instead.
Overall this should be a key component of many Japanese aircraft, just like any other way of protecting the fuel tanks. After all the game makes a clear difference from non self-sealing tanks to self-sealing tanks. Similarly Soviet aircraft have had neutral gas pressurization system from the very beginning of the game. Functionally it would be very much like the engine fire extinguishers already in game and would likely be a researchable modification.
A list of planes which are known to have had this system. Among them are bombers and several prototypes:
Spoiler
A6M5 and all following variants, but only in wings
A7M1, A7M2
N1K1-J, N1K2-J, N1K2-Ja
J2M all variants
J5N1
J6K1
Kikka
D4Y2*
B6N2, B6N2a*
P1Y1
H8K2, H8K3
Ki-21-II very late production
Ki-48-II very late production
Ki-49-II late production
Ki-67
Ki-61-I Hei and Tei
Ki-61-II Kai
Ki-83
Ki-93
Ki-100-I and -II
Ki-102
*These might have had just engine extinguishers.
For now I have not found mention of these in game fighters having the system, though I would bet they had it as well:
Spoiler
Ki-87
Ki-94-II
Ki-108 (build from Ki-102)
Ki-109 (build from Ki-67)
J7W1
Ki-84 appears to be a notable exception, specially considering how numerous fighter aircraft it was in the late war. One of the documents listing CO₂ canisters has an empty line for it and there are very detailed reports about this fighter, which would likely mention the system if it was there.
One of the sources mentions IJA used nitrogen extinguishers, but it’s not said if it was in all of their aircraft and if it was practically different to CO₂.
Sources
Spoiler
U.S. Strategic Bombing Survey: Translations and Interrogations number 22, pages 25 and 32
国立国会図書館デジタルコレクション
Technical data. Report No. 16a(9), Mitsubishi Heavy Industries, Ltd., Corporation Report No. 1
国立国会図書館デジタルコレクション
Operational Japan fighters. Intelligence summary no. 283-4 August, supplement CONTENTdm
Exploding Fuel Tanks 2nd edition, Richard L. Dunn, 2023
Japanese Heavy Fighters 1937-1945, Dariusz Paduch, 2022
Japanese Secret Projects: Experimental aircraft of the IJA and IJN 1939-1945, Edwin M. Dyer, 2009
X-Planes of the Imperial Japanese Navy & Army, Nohara, 2000
Famous Airplanes of the World: Kyofu, Shiden, Shiden-Kai Extended Edition, Bunrindo, 2020
IJN Kawanishi N1K Shiden, Shiden-Kai, pictorical book Maru Mechanic, 1980
Kawasaki Ki-61 Hien / Ki-100 (Monographs), Leszek A. Wieliczko, 2014
