Finally I had time to add few more sources and revise the text. One of the sources even mentions fuel tank extinguishers was used by some Ki-21, Ki-48 and Ki-49 bombers. All three types remained in production to 1944.
It’s possible that their line of thinking was that since fuel would be consumed from the wing tanks first (which I don’t know if its the case), by the time they engaged in combat those tanks would be empty and wouldn’t need self sealing protection.
CO2 extinguishers were there just in case you got jumped, and the fuselage tank still got you home.
That would have likely been the case on short range interception missions. J2M had most of it’s fuel in the fucelage tank after all. Some document even mention early J2Ms having removable wing tanks. Even so the decrease in fuel tank capacity is stated as the main reason. While production N1K2-J had self-sealing wing tanks, they still wrote down what the fuel capacity would be with plain unprotected metal tanks.
Interesting thing in devserver update log, though it’s only X-Ray. I can’t think of what else it could be than a strange way to implement CO₂ or nitrogen extinguishing system.
There are way more tanks than 5, but I’m quite sure they are merged into groups like this. Numbers 2, 3, 4, 5 should be all the wing tanks and the missing #1 would be the fuselage tanks.
Probably some minor buff to fire resistance. But it’s still based on luck, just lower chances presumably.
Was spading the Pe-3 which also has neutral gas pressurisation and I cought some .50cals from a P-39 that turned my fuel tank yellow but started a fire that burned down my plane.
oh wait there is information about Japanese fire extinguishers in US documents?!
I was wondering why they’ve not described it when Japan was number 1 in number of aircraft models which had it
I’d imagine there must be bit more somewhere, like what they thought about the system. For Americans it would have been difficult to find a working example to test, so any proper test report would have likely been from autumn 1945 at earliest.
That one is from TAIC summary #32 “Evolution of Zeke”. Might be worth it to check all the others which can be found. There are at least 41 in total, but for some reason very few are available online. TAIC Summary Reports Japanese Aircraft | Page 2 | Aircraft of World War II - WW2Aircraft.net Forums
Earlier I haven’t checked any, because I thought they had just the basics. At least armor is described a bit better in them.
During the war, both IJN and USN used CO2 system on their aircrafts. J2M receives CO2 system for its wing tanks, which was not self-sealing and usually do not contain fuel in air combat. Same for the F4U, which too has non-sealing wing tanks, equipped with CO2 system, but rarely used in action. For both J2M and F4U, their main fuselage tanks were self-sealing and thus did not receive CO2 system.
It looks like that the CO2 system was used only as a secondary method of protection for non-sealing fuel tank, and was not as effective as self-sealing tank covered with bullet-proof rubber. Thus A6M5 got it only as an emergency method for protection. The only fighter aircraft that equipped with both self-sealing fuel tanks and CO2 system was the N1K. From the combat records, the CO2 system did work sometimes and saves the life for the pilot, but most likely the aircraft would still burst into flames if hit by multiple shots. Whether the CO2 system onboard the A6M and N1K were standard equipments was unknown, the TAIU did not find CO2 system on captured A6M and N1K in Philippines.
In the current game, the fuel tank fire was defined by the damage model file, which contains information for flammability of the fuel tank. We already see Ki-84 tanks have the chance of fire equal to that of Lavochkin equipped with “neutral gas pressurization system”, and for Yaks, the chance of catch a fire is even lower. If we do see such CO2 system implemented on the A6M and N1K, it would only mean the change of the value of flammability in the damage model file.
In J2M all fuel tanks were protected by CO2 system. A7M was the same in that regard. Late A6Ms were kind of the opposite: All tanks had rubber coating and only front fuselage tank lacked CO2 system. I’d really like to know in more detail what Navy and Mitsubishi had in mind. Armor protection in Navy fighters was also rather unique.
It is clear the earliest systems in IJN were there only for saving the ejecting crew from burning plane. Of course in rare case it could save the whole plane, though unprotected tanks would quickly leak empty. In game distances are shorter and heavily damaged planes are still quite easy to fly, so I believe it would make a small difference.
Definitely. The system doesn’t make tanks foolproof. Heavily leaking tanks are easy to ignite again and the system only has one shot for each tank. In addition the system itself could be damaged. Then again one of the sources states that even heavily damaged tank could be extinguished with high chance.
It is bit difficult to determine when the system was installed in Zeros and Shidens and what exact variants were deployed where. Zeros with Sakae 31s or 31As had were already captured from different island, but among them were Sakae 21s. Many different nonstandard armament variations were also listed.
About Shiden deployment we know a bit more. I’m quite certain no Shiden Kais were deployed outside home islands. Even Shidens with 4x20mm mounted inside wing were not captured as far as I have found.
Many captured aircrafts had already been cannibalised for parts, though indeed it is possible not every unit received the system. It is annoying how few intelligence reports we have about equipment found only from home islands.
It has been long since I checked any of those fire chance values. How arbirary do they look? I don’t see any problem with implementing the system as active system, just like engine extinguishers or the extinguishers in ground vehicles.
And IJA also. It was limited and we have less sources but I will write about it later
To be clear, was it the fire extinguisher systems? Not the neutral gases filling of fuel tank. As I know for example, Catalina had the filling with CO2 from bottles, not extinguisher.
Also interesting was it automatic because
According to Japanese book it is not true. The wing tank had this system. Probably here was the upgrade which wasn’t mentioned in books
Spoiler
Do you have the source for your words?
Here is the Japanese results of testing this system for G4M Betty and it showed the 95% of effective against 3 hits with 12.7mm IAI round.
The effective of Japanese fire extinguishers was caused the construction and the fact that all of systems at all aircraft was automatic. It is because Japanese tests shows that this system will be effective only if it will work in 0.3-0.5s after starting fire so only automatic systems would be effective.
It used the special detectors to find fire
It is important to note because here is example of IL-28 which had fire extinguisher systems for fuel tanks but it wasn’t automatic.
Also wanna say that the list of Japanese planes with fire extinguishers is a little bit bigger. It was found:
Japanese sources:
N1K
A6M5 and later (funny that not Japanese souces says only about A6M5 Otsu model, when Japanese says just about Model 52)
J2M3 and later
A7M
J7W
Kikka
Ki-67 (interesting that it had long story of different anti-fire equipment)
G8N
Late G4M versions (not in game)
US document what show the number of CO2 bottles which was used for fire extinguishing. It is not said where it worked but the number of bottles says that it is not for engine:
H8K2/3
P1Y
Not Japanese books:
Ki-102
Ki-93
Ki-61 Hei and later
And it is what was found. It is possible that much more aircrafts, for example G5N or IJA planes had it.
Do you have the source for it? I mean, the sources that it was just a “emergency method”. The A6M5 system was similar to what can be found on other IJN planes. Also need to note that A6M5 Hei, where all tanks was covered, had this system
As I wrote before, here were many aircrafts with this system and their tanks was covered.
The problem with this records that it is survivorship bias, this records can’t show all the statistic.
It is known that this system included in manuals so it was standardized equipment and could be added in WT for it
I would say US recorders wasn’t so good and people often see so I won’t be surprised if they just missed it
Is it? I haven’t checked datamines for this tbh. Could you show it please.
Could I ask you what you mean as earliest systems? The engine fire extinguishers?
There were several types of this systems from IJN and IJA.
IJN:
CO2 system what is clearly known which uses the detectors of fire and automatically activate fire extinguisher system
The rubber with fire extinguisher liquid Carbon Tetrachloride which was covered over all fuel tanks. In case of hitting tank, this cover hitted too and liquid enter the firing tank. Easy and effective as it was said by Japanese data.
IJA:
Similar system as IJN CO2 but used the Nitrogen as gas for fire extinguishing
The coating with Carbon Tetrachloride as on IJN planes
Tbh I think that unfortunately here isn’t enough data for saying that it can’t save whole plane.
Yes it is true, but here isn’t any mechanic for start fire the leacking tank so it would be effective.
Japanese sources says about A6M5 (not Ko or Otsu, the initial one) and N1K2 (I don’t remember was N1K1 mentioned there)
Yes, it is very needed in game but in case of Japanese planes it should be automatic
Very interesting. There were also some other changes to J2M wing tanks, but I can’t remember too well what it was. At any rate the fuselage tank is said to be very thick skinned.
I probably oversimplified a bit. With “early systems” I refer to variants of A6M, D4Y and B6N, which still had manual CO2 system and no self-sealing tanks. Before any kind of fuel tank protection, a fuel tank fire in these aircraft often quickly turned into an explosion, which killed and wounded many aircrew before they could jump.
So it is claimed these early systems were there to prevent those explosions. Quite hard to prove for certain. In my view it makes sense as these planes would suffer significant damage before crew would have reacted to activated the system. Of course somekind of survivor bias would be caused due to lack of other protection in these planes.
Ki-93 I believe would be true. I wish I had proper Japanese sources about it.
Ki-102 maybe, though it should have room for thick enough tanks.
About Ki-61 I’m very suspicious. There are no traces of the system in any pictures and only few mentions. First mention is in a vague book and second one probably just repeats it.
It is odd how those sources mention Hei in specific. Production of Hei began almost immediately after Otsu and they continued in parallel for many months with Tei. I guess it might have been tested at some point, but not taken in major use when self-sealing tanks became sufficient. The upgrades to Ki-61 fuel tank protection are known very precisely, yet there is still something missing.
But it is different system. This planes had the engine fire extinguisher systems which was manual. It could catch the fire from fuel tanks and was needed for using during start engine on ground or use it in air.
So it can’t prevent the fuel tanks fire because it wasn’t connected. As I read, the automatic fire extinguisher system for fuel tanks was created without any earlier manual version.
Yes it is most doubtful thing what I’ve found. That is why I wrote that it is not Japanese sources
In J2M all fuel tanks were protected by CO2 system. A7M was the same in that regard. Late A6Ms were kind of the opposite: All tanks had rubber coating and only front fuselage tank lacked CO2 system. I’d really like to know in more detail what Navy and Mitsubishi had in mind. Armor protection in Navy fighters was also rather unique.
the J2M only used CO2 for its unprotected wing-tank, and the main fuselage tank was protected by bullet-proof rubber and thus no CO2 system was installed for it. This was mentioned in both 雷電仮取扱説明書 and TAIC inspection of captured J2M3 aircraft.
I said
Thus A6M5 got it only as an emergency method for protection.
Because this was a consensus among both USN and IJN that the CO2 system was not as effective as self-sealing fuel tank covered with thick rubber. Thus installing CO2 on A6M5 was a sub-optimal solution to increase its survivability while not increasing much weight and reducing its fuel capability.
In current game, early A6M5 having a fuel fire chance of damage r=10, fire rate = 0.7, with CO2 system it should be lowered to fire rate = 0.5, i.e similar effect with conventional self-sealing fuel tank. And for N1K2 and A7M which equipped with both self-sealing tank and CO2 system, the fire rate should be r =0.3, equivalent with Lavochikins that equipped with nitrogen pressurization fuel tank.
It should be noted that CO2 system was not very effective in real life, and later on aviation turned to use nitrogen inert system to prevent fuel tank fire as standard.
This is the in-game file for ki-84’s damage model, its fuel tank receives inert as the fire rate even lower than La-7’s nitrogen fuel tank.(ki-84 receives 20% damage to have 30% chance fire, la-7 receives 10% damage to have 30% chance of fire)
Which is already much better than self-sealing fuel tank used by US and Germany, for example P51 receives 10% damage to have 50% chance of fire, which is much flammable than Ki-84.
This is where determines the damage behaviour of an aircraft, of course one could argue to make tanks with CO2 system to have a chance of fire somewhat lower than conventional fuel tanks.
The rubber with fire extinguisher liquid Carbon Tetrachloride which was covered over all fuel tanks. In case of hitting tank, this cover hitted too and liquid enter the firing tank. Easy and effective as it was said by Japanese data.
If you have the first-hand source about the coating, I am interested to know it. As I haven’t read any record on using Carbon Tetrachloride in self-sealing tank, nor they were mentioned in any japanese manual. They only mentioned “防弾ゴム” which was conventional leak-proof rubber covering the tank. The tank on captured Ki-43 proved to be poor against US .50cal during the test.
To be clear, was it the fire extinguisher systems? Not the neutral gases filling of fuel tank. As I know for example, Catalina had the filling with CO2 from bottles, not extinguisher.
Indeed early F4U used CO2-purging system, when activated, CO2 would be pumped into the gas tank and purge out any gas vapor inside, similar to a nitrogen inert system. It is clear that a fuel tank purging/inerting system works better compare to a CO2 extinguisher activated by heat sensor after 0.5s after the fire. Since the inert gas have already prevent gas vapor inside the fuel tank to be ignited/ cause an explosion, the extinguisher did it only afterward, and the CO2 gas was only pumped outside the tank, thus less effective.
Once the fuel tank been hit by API rounds, the hydrodynamic wave would easily erupt the tank, even for the self-sealing tank ( US test for .60cal round shows only 1 round to cause such failure, for .50cal more hits might be needed, determine on the distance) , the fire would be catastrophic that CO2 could help little. The system may work well for small leak fire though.
As for the game, the War Thunder lacks a clear fire system to distinguish a small leak fire, medium fuel fire or catastrophic fuel explosion, as the il2-1946 has. All fuel tank fire in the game was defined equally catastrophic, which isn’t correct and would be incompatible to implement such CO2 fire system.
Here is a very good gun-camera footage that shows the effectiveness of the CO2 extinguisher onboard N1K2, took place in the air battle over kikai-jima.
First, N1K2 receives one-hit around the cockpit, then 2 seconds later, a short burst of M1/M8 API hit the right wing and engine compartment, right wing tank immediately exploded.
The fire then diminished, could be suppressed by the automatic CO2 system.
Around 5 seconds later, the N1K2 flies outside the gun camera, the right wing fire resumes to grow, presumably the CO2 was exhausted.
If this is the video I think it is, then it’s been deleted. Definitely the big fire must have been from fuel tank, but other than that is uncertain. If I remember right, there weren’t many tracers shown, which made it impossible to tell if the American fighter continued firing. Of course it doesn’t make much sense to just stare at an enemy fighter without firing at it. At any rate it kind of illustrates CO2 system’s most obvious limit in such situation, which is the one time use for each tank.
Probably a temporary solution. I have never seen other mentions of it. Use of nitrogen isn’t mentioned that often either, while it seem to have been in common use in the IJAAF. Would be nice to know what was the reason for using it over CO2 or other way around.
.60 cal had kinetic energy closer to some 20mm rounds. It is curious how many airforces developed such an inbetween caliber, but ended up abandoning those projects. Only German 15mm saw some use.
For 13mm one of the sources gives quite positive numbers:
“The performance of this system was so excellent that even if a large amount of gasoline leaked and ignited after being hit by an incendiary round from a 13mm machine gun, carbon dioxide gas would spray out within about 0.3 seconds, and the fire extinguishing rate reached 95%”
Too bad 13mm incendiary could mean any Japanese or even American 12.7, 13 or 13.2mm which had incendiary content. Again not very good if the enemy is sitting behind and continues firing, though a possible lifesaver if it’s only a short pass.
Damage and ignition are also extremely simplified. Incendiary load means just a %, no matter how it is loaded in the round. Lone incendiary tipped bullets shouldn’t be that effective as rounds meant to first penetrate and then release their load.
Still I don’t see issues with CO2 system in game. How it differes from the engine fire system in that regard? Lowered ignition % is not the same, as it remains after fire and does nothing if the tank is already in fire. Why do you think it should be modelled like that?
Damage and ignition are also extremely simplified. Incendiary load means just a %, no matter how it is loaded in the round. Lone incendiary tipped bullets shouldn’t be that effective as rounds meant to first penetrate and then release their load.
In current game, pure incendiary round such as M1 incendiary on M2 machine gun does little effect on setting on a fire, since it could barely penetrate the airframe and touch the fuel tank. Most of the time one have to rely on API round, or HE round with real-shatter effect. And if you saw my previous posts, the fuel tank has different load setting, sure random hit may cause 1-3% of fire, the main cause of fuel tank fire happens only after reaching the first load stage ( when fuel tank has lose 10-20% hp value). In real life it would mean a tank with multiple holes, and gas vapor fully spread and mixed, once ignited, a small explosion is expected.
“The performance of this system was so excellent that even if a large amount of gasoline leaked and ignited after being hit by an incendiary round from a 13mm machine gun, carbon dioxide gas would spray out within about 0.3 seconds, and the fire extinguishing rate reached 95%”
I would say that proved CO2 system works for small fire caused by igniting the outside leak. However, such a fire could also saw been put out simply by diving to a faster airspeed, this was observed on some gun camera footage on Ki-43 and Ki-84. When dealing with ignited gas vapor inside the fuel system, the CO2 spray could do little.
Of course it doesn’t make much sense to just stare at an enemy fighter without firing at it. At any rate it kind of illustrates CO2 system’s most obvious limit in such situation, which is the one time use for each tank
In the footage, the spark caused by I/API rounds were quite obvious, the N1K2 received two short-burst before the fire, and no hit was observed after the fire was set. I’d say the pilot had to dive the aircraft simultaneously as the CO2 system is activated by fire, otherwise once the CO2 got exhausted after a few seconds, the fire may still continue, or the temperature was still too high to start another fire.
