v90 Guide: eliminating flash fires/detonations

[Evil4Zerggin]

With their potential to destroy your beautiful battleship in a single hit, eliminating the chance of flash fires and detonations is naturally of great interest to any UA:D ship designer. There are two ways to completely eliminate the chance of flash fires and detonations.

Method 1: Thicc turret armor

As long as the perpendicular effective thickness (i.e. including quality but not including angle) of a turret's armor is greater than the penetration of the shell (including angle), the flash fire/detonation roll will never happen at all. Just look at the penetration values for the guns you're likely to face to decide how much to put on. Note that you will need both side and roof armor.

This is the method I use most often since it doesn't require any specific techs, hulls, or components.

Of course, small guns may not be able to carry enough armor to prevent the flash fire/detonation roll. Fortunately, there are some mitigating factors:

• Small guns are less likely to be hit in the first place.
• Small guns deal less damage if they do get flash fired/detonated.
• Secondaries can't be flash fired, only detonated, and you can get away with about 25% less armor thickness against detonations compared to flash fires.

Torpedoes can also cause flash fires/detonations, using an effective penetration value proportional to how much damage they do after reductions from torpedo belt and Torpedo Damage modifiers. I haven't run the numbers but generally if you have max belt you'll be good against torps if you have enough armor to be good against guns. But if you have no belt you're going to have problems if you get torped.

Method 2: Modifier stacking

This method is simple: just stack flash fire/detonation chance modifiers until they reach -100%.

I only use this method on high Resistance builds that allow me to remove armor from the turrets (and the rest of the ship). Unlike turret armor, flash fire/detonations modifiers alone don't protect your turrets from being knocked out, which is less bad than getting flash fired but is still bad. On the other hand, if you have enough Resistance to soak the turret hits this can be quite cost- and weight-effective.

For flash fire chance (note that to nip them in the bud you want just "Flash Fire Chance", not "Flash Fire Explosion" or "Flash Fire Spread"):

• Barbette thickness: Barbette IV (1915) gives -17.5%.
• Reinforced Bulkheads: Reinforced Bulkheads II (1915) gives -12.5%.
• Citadel: Turtleback (1916) gives -15%.
• Shell weight: This ranges from -10% for Light shells to +30% for Super Heavy Shells.
• Shell propellant: Tube Powder III (1935) gives -45%.
• Passives: "Composite propellants" (1916) gives -5% and "Advanced bursting charge" (1921) gives -2.5%.

All in all, there is -107.5% available, so there's at most a margin of 7.5%, which you could trade 5% of to downgrade to Barbette II. Though for a Resistance build this won't save much at all. Alternatively, if you're willing to accept a small (1/40 of base) flash fire chance (or use AoN Citadel but that loses a bunch of Resistance), you could trade 10% to use the earlier Tube Powder II (1930) or Standard shell weight. Between Resistance and the required propellant tech, this is definitely a late-game strategy.

Here are available modifiers for detonation:

• Fuel: Coal gives -7.5%, but this become unavailable, and the best you can get from fuel is -2.5% from Semi-Oil. Overall not a big factor.
• Barbette: Maximum (1915) gives -25%.
• Citadel: Turtleback (1916) gives -30%. Since we would use this method with a Resistance build, there's no reason to use any other citadel type.
• Shell weight: This ranges from -15% for Light shells to +35% for Super Heavy Shells.
• Ammo amount: This ranges from +0% to +25%.
• Shell propellant: For Tube Powder this is the same as for flash fires.
• Shell charge: TNT II (1913) gives -25%.
• Passives: "Composite propellants" (1916) gives -5%, "Advanced shell fuse" (1919) gives -8%, and "Advanced bursting charge" (1921) gives -5%.

All in all, there is more than -150% available, so this is usually less of a concern than flash fires, but don't go too crazy with torpedoes etc. Unfortunately this doesn't seem to be shown at all in the designer.

Edited October 1, 2021 by Evil4Zerggin

[Evil4Zerggin]

On a second look, it seems like getting -100% Flash Fire Explosion Chance will work just as well. Here are the modifiers:

• Barbette: Maximum (1915) gives -25%.
• Turret rotation may give a penalty.
• Light Shells gives -10%.
• Ammo amount gives -10% to +10%.
• Shell charge: TNT II (1913) gives -25%.
• Shell propellant: For Tube Powder this is the same as for the base Flash Fire Chance at up to -45%.
• Passives: Again the same as the base Flash Fire Chance. "Composite propellants" (1916) gives -5% and "Advanced bursting charge" (1921) gives -2.5%.

Here the total reaches -122.5%, which gives a larger margin of 22.5%. Possible trades are:

• Lighter barbette.
• Turret rotation components (2.5% or 5%).
• Heavier shells (10% per step).
• More ammo (10% per step). I usually pick this since lightly-armored Resistance builds favor autoloaders, which when combined with Light shells chews through ammo in a real hurry.
• TNT III instead of TNT II (12.5%).
• Earlier versions of Tube Powder (10% per step). This could push the date forward to as early as 1916 if also skipping the last passive (2.5%)? Though the best Resistance hulls don't unlock until later anyways.

[RedParadize]

Btw, you should take a look at resistance stacking. Combined with flashfire removal you can make ship that do not need armour.

[Evil4Zerggin]

10 hours ago, RedParadize said:

Btw, you should take a look at resistance stacking. Combined with flashfire removal you can make ship that do not need armour.

I gave an example in this post.