In gameplay point of view, it can be easily done like the cargo wagon.
But in realistic point of view, upgrading the shell to the same standard of protection would be several times thicker and ridiculously heavy. A single rupture is enough to leak most of the stored fluid, may even ignite the whole thing.
An analogy would be flamethrower' fuel cylinder. Upgrading it to be bulletproof like body armour, would make the capacity/weight ratio so low that it is not feasible. Otherwise, arms designers and military experts would have already assigned protection to it, rather than leave this fatal vulnerability to enemy.
Therefore, I found "armoured fluid wagon" is neither realistic nor logical, when I was deciding what to include.
So what do you think? Any reason(s) to justify implementing this item?
However, in my personal humble opinion, I think that it's possible. The cylindrical shape is more resistant to punctures and pressure. So it could be used as an advantage and a new option for adding such item to the game.
Like, when the said wagon is destroyed a small explosion is triggered, additionally setting aflame a small area near the explosion. However, that would qualify as an additional feature.
Secondly, it does not have to be AS sturdy as armored cargo wagon, for example, giving only 50% bonus to its HP pool,
full bonus to resistances, EXCEPT acid,
minimal weight increase (no more than 40% of normal liquor wagon).
Introducing only one armored liquor wagon without further upgrades. Additionally making armored liquor wagon require advanced materials like:
normal liquor wagon x1,
Low-density structure and/or
It would be much sturdier than one made out of conventional materials. And when applying IRL physics it would make it slightly lighter.
Of course, exposing to the enemy valuable materials like Oil is foolish to begin with. But when it needs to be done it has to be.
I will respect Your decision, I got the answer I was looking for. You aim for realism, I, however, could see a use for slightly armored liquor wagon in my playthrough. As all my Oil fields are Very far away from my base. Making, as You have proposed, guarding the whole track, an unfeasible task.
Adding to the discussion, bitters/spitters don't use bullets/projectiles other than acid spits. So there is no incentive to add for example kevlar plating, unless there are other survivors which crash landed with You (pvp)
One of the central ideas of my modding is that, my mods are not only for PvE, but for PvP as well. So things should be well balanced: so no OP items. Anything with some great advantage must also come with big disadvantage. So things like long range guns must be balanced with expensive tech/recipe and/or very low rate of fire. High DPS guns would have short range and/or slow to use. Extra long range rocket artillery (which is napalm capable) would come with slow and fragile chassis, weak to explosives, so enemy team can use light tank to counter that. So balance have a really high place in my consideration.
As from the vanilla setting of several armours and tanks, the crashlander (character) do NOT assume the alien attack would only be acid spits. The resistance settings of power armours and tanks are actually well-rounded, actually relatively weak against acid. So there is no reason why a reasonable armoured wagon would be good against acid, but ignoring things like physical and explosive damage.
But your earlier comments have some valid points I can consider. There can be armoured fluid wagons, but with the following downside:
Due to the physical shape of the wagon, it would never have as much increase in structural strength (health and resistances) as armoured cargo wagon. The ratio of weight increase would also be higher. The fluid capacity would also be below 50% of standard fluid wagon.
The equipment grids can be expected to have similar size. So grids of armoured fluid wagons would share the same benefit (grid size and equipment types) for that of armoured cargo wagons.
For example, the armoured fluid wagon MK3 would have energy shields, and also rely on them to absorb incoming damage. Once shields are out, its physical protection would be not much better than the (unarmoured) fluid wagon.
I would need these big nerfs to make it a logical and reasonable entity. If you think it is unacceptable, then I may give up the idea.
Regarding the triggering, it may be difficult to script in gameplay-wise.
For vanilla fluids, I can hardcode which fluids are flammable. But it is impossible to assume that for modded fluids.
Maybe I can just consider only leaking (so no suicide fluid wagon fireworks). When a fluid wagon got damage, the amount of leakage will be related to amount of damage inflicted. Wagon below 50% health will loses all its fluid content.
But still it is only an idea. Game API and UPS consideration may limit such implementations.
Sorry for the long wait.
Finally included armoured fluid wagons for the recent release 0.17.5.
For simplicity, I did not nerf them as much as expected above: the structural strength has the same upgrades like the armoured cargo wagons. The only big nerf lies in the capacity: 10k fluid per wagon (vs 25k in vanilla wagon).
Have not introduced any script regarding damage status yet, could be a good feature, but probably when I have more time to do that.