Troop Compartments

[SevenOfCarina (OP)]

Combined-arms formations are not particularly useful in Aurora. In real-world military formations, infantry units screen vehicles from hostile infantry attacking from ambush, while vehicles provide mobility and the firepower to breach fortified positions. There is no mechanistic advantage to mixing infantry and vehicle units right now, and the targetting disadvantage actually makes such formations useless. I want this to change.

To that end, I'm proposing the addition of an infantry-carrier module for vehicles:

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Troop Compartment   Size: 20 tons   Capacity: 40 tons

At the start of each combat round, the total infantry capacity of all vehicles in each formation is calculated.

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Formation Infantry Carriage = sum of troop capacity of all vehicles in the formation, discluding vehicles in subordinate formations

Then, the mean armour of all vehicles in each formation is calculated.

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Formation Mean Armour = size-weighted mean of armour values of all vehicles in the formation, discluding vehicles in subordinate formations

Finally, all infantry elements in each formation are assigned an adjusted armour value based on the FIC and FMA that is used for combat calculations. Note that the Effective Infantry Armour cannot exceed the Formation Mean Armour.

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Effective Infantry Armour = (Formation Mean Armour) × (total size of all infantry units in the formation) / (Formation Infantry Capacity)

For example, consider the following formation consisting of light tactical vehicles, infantry fighting vehicles, and infantry equipped with personal weapons and crew-served weapons:

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Mechanized Infantry Battalion
2 × Command Vehicle
40 × Infantry Fighting Vehicle
60 × Light Tactical Vehicle
800 × Assault Rifleman
120 × Machine-Gun Team
Transport Size: 9680 tons


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Command Vehicle
Transport Size: 80 tons   Armour: 40   Hit Points: 40
Headquarters   Capacity: 10,000 tons
Crew-Served Anti-Personnel   Shots: 6   Penetration: 10   Damage: 10

Infantry Fighting Vehicle
Transport Size: 54 tons   Armour: 40   Hit Points: 40
Light Anti-Vehicle   Shots: 1   Penetration: 20   Damage: 30
Troop Compartment   Capacity: 40 tons

Light Tactical Vehicle
Transport Size: 32 tons   Armour: 20   Hit Points: 30
Troop Compartment   Capacity: 40 tons

Assault Rifleman
Transport Size: 5 tons   Armour: 10   Hit Points: 10
Personal Weapons   Shots: 1   Penetration: 10   Damage: 10

Machine-Gun Team
Transport Size: 12 tons   Armour: 10   Hit Points: 10
Crew-Served Anti-Personnel   Shots: 6   Penetration: 10   Damage: 10

This formation has a total FIC of (40×50 + 60×50 = 4000 tons), and has 5,440 tons of infantry units in total. There are 2,160 tons of IFVs (armour 40) with troop capacity, and 1,920 tons of LTVs (armour 20) with troop capacity. Hence, this formation has an FMA of ((2160×40 + 1920×20)/(2160+1920 =  30.59), and an EIA of (30.59 × 4000/5440 =  22.49 ~ 22.5).

When attacked, all infantry elements in this formation will be treated as having an armour rating of 22.5 instead of their actual armour rating of 10, making them approximately five times harder to kill with standard anti-personnel weapons. The EIA will be re-calculated at the start of each combat round, so destroying vehicles will make infantry units more vulnerable. The idea here is that the presence of vehicles makes infantry significantly harder to kill, so they aren't depleted easily by anti-personnel weapons and stick around to soak up damage from heavier weapons, protecting the vehicles.

While this might seem like an extremely strong buff at first glance, the protection afforded to infantry comes at a significant cost - this ~10,000 ton formation costs as much as an ~18,000 ton pure-infantry formation (or a little less than a ~10,000 ton pure-infantry formation with power armour, which has less armour but nearly twice the firepower since it doesn't have the dead-weight of troop compartments). Armoured vehicles are expensive, and the addition of troop compartments prevents them from being able to equip weapons, so there is a trade-off involved.

The exact numbers may need to be tweaked, but I think this framework adds depth without removing choice. Mechanized infantry formations are well-protected against anti-personnel weapons and space-efficient, at the cost of lacking firepower. Power-armour infantry formations are not as protected but have better firepower while retaining space-efficiency. Finally, for the same cost, regular infantry formations have the greatest firepower and the highest health but are very space-inefficient.

[nuclearslurpee]

This comes up a lot, and usually the key point that is missed is that the current system offers neither an advantage nor a disadvantage to using combined arms formations. This is extremely important from a roleplay perspective - it is important to remember that Aurora's ground combat model needs to be capable of modeling not only "realistic" formations based on real-world militaries but also decidedly unrealistic formations such as WH40K Guard Regiments (a universe where combined arms are doctrinally forbidden, if rather less so in practice).

To wit:

There is no mechanistic advantage to mixing infantry and vehicle units right now,

This is correct, and allows the above goal to be met.

and the targetting disadvantage actually makes such formations useless.

The what?   

I am unaware of any "targeting disadvantage" in the mechanics. Targeting in Aurora ground combat is completely random, weighted only by the size of formation elements. It has been discussed many times that any other mechanism to give a preferential targeting effect forcibly pushes the equilibrium towards mono-type formations, e.g. all-infantry or all-tanks, rather than towards combined arms, unless further base mechanical changes are added (which in turn resets the entire balance, requiring massive playtesting burden on Steve who probably wishes to do other things).

The current system does have some important flaws which remain to be worked out, but mechanically I do not think we need to find ways to force combined-arms formations as the meta when this will come at the expense of roleplay. I think it is sufficient that, at present, combined-arms formations are viable (there is no downside to using them, mechanically) and that combined arms are arguably optimal at the level of a full force - i.e., it is best to have a mix of tanks and infantry (for example), but it is not important that they are organized in one way versus another.

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As far as the actual suggestion, I don't mind it although I think it is rather over-complicated and may not realistically represent actual tactical use of IFVs, etc. which seems to defeat the point a bit. However, I think it is an interesting idea from a roleplay perspective and doesn't appear to break anything. I might suggest to simplify the calculation to avoid the summation over average vehicle armor, either by using a flat multiplier (e.g., x2) or probably better would be to apply a flat modifier to evasion - representing that the infantry are harder to target when transported, rather than "armored" even when dismounted.