Fuel Tank Explosions Should Not Happen

Machinery of War Discussion Ground Vehicle
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Finally I had enough of this stupid mechanic and did a dive into the physics of it. I can understand the devs thought process (assuming they actually took a look at the chemistry behind it) but they did make a pretty big error that should be obvious to anyone: fuel tanks aren’t supplied with unlimited air/oxygen.

Let me break it down for you:

Fuels can ignite and explode. It requires a flammable substance, oxidizer, and a source of ignition. When penetrated, even by an APFSDS, we have met 2 of these conditions being flammable fuel and an ignition source since the temperature of the projectile and the fragments will be above the flash point and possibly above the auto-ignition temperature. HOWEVER we are missing the third aspect, where’s the oxidizer?!

Well, the fuel tank is filled primarily with liquid fuel and since fuels are typically volatile it also is filled with fuel vapors as they evaporate and re-condense, and some air remains. The fuel tanks are sealed and not open air. Most of the air gets pushed out when fueling so we know it is a small concentration. We also know that fuels have a Flammable Range which dictates the needed % of fuel vapor in air by volume to ignite/explode. For diesel, the most common fuel for tanks it has a range of 0.6 to 7.5% typically. This immediately puts us over the upper flammable range limit and we now know inside the fuel tank it is too rich to ignite, i.e. not enough air.

I’m guessing the devs might not have known about the Flammable Range, but unless these fuel tanks are suddenly a big open air fuel tank or is hooked up to an oxygen tank, it will not explode.

In addition, we can also see that fuel fires are too common in game. A brief fire may start from the projectile being above auto-ignition temperature and there is locally enough air present to support combustion of a small amount of fuel, the fire will quickly suffocate and put itself out, unlike what we have in game.

Here is my bug report on the topic: Community Bug Reporting System

Hopefully we can get this mechanic removed because it is beyond frustrating having 90% of my deaths do to this stupid mechanic.

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Er…jet fuel is explosive …always was.Maybe if War Thunder did a moon map you would be fine.As maps are currently I wouldn’t rule it out.

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All fuels are explosive. They are defined by their Flammable Range. Fuel tanks are sealed and are not open air, the environment inside them != atmosphere chemistry. You cannot assume the environment inside a filled and now sealed off fuel tank is the same as the external environment, especially when the fuel is volatile and evaporating, that is engineering neglect. I outlined in the bug report and even in my report at vapor concentrations by volume of air above 7.5% diesel will not explode even given an ignition source or at auto-ignition temperature. That is the chemistry of it, and many other fuels. Why do you think you can suffocate a fire with fuels? This is simply the chemistry behind it.

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You are overlooking a few key steps:

  1. Impact: A high-velocity round penetrates the tank’s armor and strikes the internal fuel tank with force. This impact will rapidly transfer energy to the incompressible fluid. The fuel tank can’t contain this energy, as a result the fuel tank ruptures and fuel is dispersed rapidly.
  2. Fuel Dispersal: The force of impact can cause the fuel to displace or spray within the tank as droplets or a fine mist. This dispersal increases the surface area of the fuel exposed to oxygen, facilitating potential combustion.
  3. Ignition Source: While fuel may be hard to ignite under normal circumstances, the impact itself or subsequent sparks from metal-on-metal contact can create a source of ignition. Hot metal fragments, electrical sparks, or the extreme heat generated during impact can ignite the dispersed fuel.
  4. Leaking fuel Even if no instant ignition occurs, the fuel won’t just despawn, but remain in the tank. Inside the tank it will mix with air, come into contact with hot machinery, other ignition sources. The fuel will also release toxic gasses or smoke (on contact with hot parts), which will force the crew to abandon the tank.

Here an example how liquid behaves inside a container when hit with a big energetic impact:

Here a demo how a fuel tank „explodes“.

https://youtube.com/clip/UgkxbsZ1JyTErqb85Chr6zxgPF3mpLMT9lzA?si=zO_kaaVhl-Y2oOsp
This demo shows how the fuel tank is burst open, that the fuel itself doesn’t ignite, and simply flows to the ground through the broken fuel tank. The fuel that ignites is the one that was displaced and dispersed into the air.

In reality it’s not the fuel that makes the tank explode, but the rapid displacement of liquid caused by the projectile. As a result of this displacement and the mixing with air, a fireball can form.

In reality the destruction of an internal fuel tank will almost always lead to the crew abandoning the tank, and with a good chance of a subsequent fire destroying the tank. In other words a fuel explosion should occur 100% of the time and be a guaranteed kill.
Even if no fire occurs, the leaked fuel will make it impossible to further operate the tank.

Note: There are different types of fuel tanks that will behave a bit differently, but these are just the basics as gajin won’t differentiate them.

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  1. Not simulated in game. Same with internal overpressure mechanics. Furthermore this depends on fuel tank and tank design along with what projectile hit it. You cannot compare a plastic jug getting hit with no support to an internal fuel tank often supported by metal backings (actual CFD of bullet going into water https://www.youtube.com/watch?v=1UtYw7BU4fE, generates a shockwave. Engineers can anticipate this and design mitigation efforts and overall fuel tank survivability for this effect).

  2. mist ignition will be rapid as the projectile already causes auto-ignition. A spray is not a sustainable combustion without a constant flow, the projectile provides a 1 time rapid flow, the rest would be from a leak. The concentration of the air could locally rise for the mist that penetrated into the crew compartment but now we at at vapor concentrations that are too low to explode.

  3. Ignition source was already covered in report. Again, ignition source is useless without oxidizer.

  4. Again, covered in report about the possibility of a fuel leak. Toxic gasses or smoke are not simulated in game. Crew would abandon tank on any successful penetration IRL, that is not relevant when discussing game mechanics unless you want any time a tank gets penetrated that everybody is auto-forced to leave their tank?

Not sure why you provided that German testing link? It disproves your point and reinforces why fuel is often used as armor. The video even says the crew would be unharmed unlike current game mechanics where such a hit would result in fuel tank explosion and your entire crew dead.

You are completely wrong about fuel tank explosion happening 100% of the time, your video literally even says the tanks aren’t exploding. What you are seeing in the video and not understanding is that is not an explosion. That is fragmentation and the shockwave caused by the projectile disturbing the liquid. Depending on the energy of the projectile and the design of the tank/fuel tanks it may indeed completely rupture, or it may not. Regardless of outcome, that is NOT AN EXPLOSION nor is that a current game mechanic.

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Both are simulated.
The first is simplified as fuel fires/fuel explosions.
The later is simplified using the overpressure mechanic.
The devs even described the mechanics as such in their respective blogs.

Toxic gasses or smoke are not simulated in game.

Again, they are simulated. You can test it, let a fire burn and you will see your crew or ammo slowly being damaged by the „fire / smoke“.

internal fuel tank often supported by metal backings

Which internal fuel tanks have metal backs? Most I know don’t. That’s why they don’t spall ingame. If they are any that are missing that armor, you should report it.

Not sure why you provided that German testing link? It disproves your point and reinforces why fuel is often used as armor. The video even says the crew would be unharmed unlike current game mechanics where such a hit would result in fuel tank explosion and your entire crew dead.

The video shows how the armored fuel tank bursts open, but as it is an external fuel tank, the fuel does not leak into the crew compartment, nor does the fire occur inside the vehicle. This test shows exactly why fuel tanks are so dangerous, and why external fuel tanks are safe.
Test it on the Strv 103 ingame. This is how it works there too.

External fuel tanks are used as armor correct. This is also how it works in War Thunder. Their destruction won’t damage your tank, nor will their fires harm the crew.

your video literally even says the tanks aren’t exploding

That’s why I put „explosion“ in quotes. It’s the word used by gajin to simplify the effects of fire, smoke, gasses and fragmentation. The video also shows it occurring on the outside of the tank, not the inside, as it would be the case for internal fuel tanks. There are enough videos in the Ukraine war showing how vehicles and tanks burn out from fuel fire - sometimes even by external fuel tanks.

Just like ingame ammunition detonations will always kill the tank, regardless of the ammunition that explodes.
As it is, a 10 crew tank ingame would die instantly, if a 5.56mm rifle round „explodes“.

The developers decided that the majority of the time, a detailed simulation of all the different parameters would not make sense, and that it will be simplified using fuel/ammo detonations.

Crew would abandon tank on any successful penetration IRL, that is not relevant when discussing game mechanics unless you want any time a tank gets penetrated that everybody is auto-forced to leave their tank?

Crews IRL don’t abandon their tank on any penetration. They generally stay with the vehicle as long as it’s safe / operational. Low quality training, or certain vehicles (e.g. volatile tanks like the T-Series), often flee their tank due to the fear of it exploding. Other times they flee the vehicle as it fills with smoke or fire, but in cases where this does not happen, they will try to retreat with their tank. There are many such documented cases.
Players that control the crew, sometimes do this in WT when they hold J to leave the vehicle.
What’s considered a „kill“ is highly important for game mechanics such as these.

Tanks in WarThunder are already much harder to kill than they are IRL.
Only older tanks use outdated internal fuel tanks, and they stopped being used for a reason.

Be happy that blowout panels, and hydraulic/ electrical fires don’t kill your tank. Or that you can replenish crew or quickly replace your guns or engine.

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The totally obvious, cant belive such a stupid post.We are firing ammo made to ignite fuel ,incendary rounds.

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The fuel explosion is correct, but it should appear on the gasoline engine rather than the diesel engine. To my knowledge, the internal fuel tanks of Chinese tanks use composite material adsorption fuel tanks, while armored vehicles use composite material filling fuel tanks. The former is characterized by adsorbing diesel into the composite material, producing only a small amount or no gasified oil, thereby suppressing explosions. The latter uses composite materials (small balls) to fill the fuel tank, which isolate the gasoline in the tank into small areas. Even if an explosion occurs, only a small area is affected. The shock wave generated by the explosion will push the diesel in other areas away, preventing a chain reaction.