A Super(ficial) Discussion on the Relative Merits of Medium Vehicle Armaments.

[Foxxonius Augustus (OP)]

 Greetings Lords/Ladies/Comrades/Admirals/Generals/Dear Leaders/Omnissiahs. I have recently run into trouble while writing a design document for a new scenario and so am seeking advice from the community. The trouble is this, while designing infantry or light vehicles is fairly straightforward, medium vehicles have more options than I know what to do with. With CAP, HCAP and anti-vehicle and auto-cannons in light, medium and heavy varieties there are ~36 meaningful options for front line combatants. That number doubles once we consider armor options.

My question then, is this. What load-outs do you prefer and why? ie. Is your choice purely stat based or is it based on lore or doctrine? Do you use a single type or multiple types? Does the tonnage of your preferred load-outs combine nicely into standardized units? Are there pitfalls that you try to avoid?

In order to avoid the detestable answer of 'it depends' *bleh* I shall narrow the requirements a bit. Lets assume the intended roll is offensive, to land on hostile occupied worlds and conquer them. eg. a world with a few (1-2.5) million tons of generic ground forces split approximately 5-1, infantry to vehicles.

Math welcome, personal preferences welcome.

To start the discussion off, here are some placeholder units I have put together as a baseline.

Code: [Select]

Dragoons
Transport Size: 12,500 tons
Build Cost: 519.1 BP
1x Heavy Cavalry Regiment HQ
10x LV - Logistics Vehicle
1x MV - LVA - MAA MAA
42x MV - LVA - MAC LAV
22x MV - LVA - MAC LAC
116x MV - LVA - LAC CAP
In my scenario I am going for a bit of Napoleonic flair while acknowledging modern features like heavy vehicles representing modern MBTs. This is one of my work in progress 'cavalry' formations. My intention is to be able to deal with light vehicles and to destroy infantry formations.

[Jorgen_CAB]

In general I like the general MBT of MAC and CAP or HCAP... this will generally rip through most defensive units (static, medium and light vehicles) and is a good all around assault tank without wasting too much MSP in the battle. If your weapons thechnology are better than your oppenents armour technology, then auto-cannons are quite effective even against heavier vehicles.

In generally I leave pure anti-vehicle weapons for more specialized units that often sit in the rear when and if the enemy infantry is killed to the point that more heavy enemy units is revealing themselves. A medium vehicles with light armour and a two heavy anti-vehicle weapons can respresent some missile armed platform that can even indirectly target enemy vehicles at very long ranges, but they are expensive to fire so you don't want to waste them against enemy infantry.

In general I like well rounded armies with allot of RP charm, so overall efficiency is not that important. I want the units to sort of feel right first and be efficient second. This means I generally have three types of troops, garrisons who are the cheap troops, regular army with average cost troops and elite forces who gets all the bells and whistles but gets deployed in much smaller quanteties.

[nuclearslurpee]

Jorgen is broadly correct here. Against NPRs, at least, CAP/HCAP tend to be the "optimal" weapon as NPR armies go heavily on basic infantry (not always true for spoilers though!), but you do still want to have some capability to defeat armored vehicles. The problem with using MAV for this purpose is the high cost in GSP per shot, since most of your shots will still overkill infantry you do not want to pay too much of a premium. MAV fires one shot and costs 16 GSP per ten rounds of combat, while MAC costs 18 per ten rounds of combat but fires three shots per round, which is a good middle ground. MAC/HAC also perform well for the cost against lighter non-Infantry units (STA, LVH) which is a useful niche. As far as CAP/HCAP goes, regular CAPis usually more efficient but HCAP will give 2.25x better penetration chance against armored units which makes it a bit more well-rounded, and is useful if the opponent has better armor tech or uses up-armored infantry units (usually this means multiple player factions are present).

But of course in practice the key is roleplay.  I usually consider VEH+MAV+CAP to be an analogue for WWII-era medium tanks, and will use MAC for main battle tanks which use autoloaders and such. Usually I vary the details of my MBTs to give flavor to a faction, in game setup I often use HVH with medium armor (4x) as the base class for MBTs and related classes. I also use a range of secondary types, for example VEH+2xLB can be a MLRS platform and with 2xLAV an anti-tank missile variant thereof. Using a wider range of vehicle types means you can have your concentrated heavy armor formations but also sprinkle some supporting vehicle types into your lighter formations for a more immersive combined-arms TO&E. The difference between light infantry for garrision duties and heavier infantry for main line of battle actions can be the allotment of heavier vehicles and weaponry rather than the same bland PW vs PWL distinction for every faction.

[Vandermeer]

My question then, is this. What load-outs do you prefer and why? ie. Is your choice purely stat based or is it based on lore or doctrine? Do you use a single type or multiple types? Does the tonnage of your preferred load-outs combine nicely into standardized units? Are there pitfalls that you try to avoid?

In order to avoid the detestable answer of 'it depends' *bleh* I shall narrow the requirements a bit. Lets assume the intended roll is offensive, to land on hostile occupied worlds and conquer them. eg. a world with a few (1-2.5) million tons of generic ground forces split approximately 5-1, infantry to vehicles.

I can give a very technical view of the "what is best" question in terms of efficiency. Though this is about the ground combat system as a whole, the consequences for choice for designing any vehicle class (so also medium vehicles), are all the same if you just want the statwise best that is. There will be some basic math as you wanted.

I just happen to have a relatively recent example in the battle with the Barnbarians of Barnard's Star:


The encounter saw their ~3200 combined troops facing of with 2 regiments of a total of 3412 of mine, but 400 of those were just supplies (the enemy had only 3 suppliers), and the Barnbarians were entrenched.
In hindsight the relative tech levels came out as:
BAR: 12 Weapon, 10 Armor, but improved genetic enhancement for +60% hitpoints
GDI: 8 Weapon, 10 Armor, no genetics

- Using PWI and Powered Infantry Armor, the 2700 bulk of their forces therefore came out with the 15AR, 16HP and 1x(15AP 12DMG) seen above.

- The bulk of my GDI forces were 2142 Troopers of 15AR, 10HP and 1x(10AP 8DMG), with additional 200 LMG/CAP and RPG/LAV each.

As can be quickly assessed from this, since the penetration mechanic is pen%=(AP/AR)^2, and the killing mechanic is also kill%=(dmg/HP)^2 the Barnbarian Warriors not only were able to have every physical hit go through armor, but also instantly kill a Trooper due to the high damage inflicted.
On the other hand, the GDI infantry would only penetrate in 44.4% of hits, and even then only have 25% chance to make that wound be fatal.
The CAP version had even less penetration, with only 28.4% hits going through, but calculating #shots/mass-factor, that still came out as a 85.3% avg hits (6 shots for 2 times the mass = 3xhits)

One can now create some sort of efficiency metric from this. Hits are all random, so design has nothing to do with it, and what matters are only those penetration%, kill%, #shots and mass, using pen%*kill%*#shots/mass-factor(base=PWI infantry=1). This shows just how much "warrior"(enemy PWI) in this scenario each unit-type is capable of killing if they were all PWI-sized and in case they hit at all.
PWI: 11.1%
CAP: 21.3%
LAV: 37.5%
...Now wait, what happened here? The last one was supposed to be an anti-vehicle type, yet it is the most effective infantry to take on other infantry? This already gives a hint to where the conclusions of Aurora ground battle mechanics go to.

To this metric above though, remember this is just firepower, not defensive qualities. Against this enemy type, the CAP only has half the DMG-sponge capacity due to being twice as heavy, and the LAV only has 37.5%. If you realize that a LAV for example virtually only has 0.375 as much "life" as a PWI, you will notice he can also only on average fire 0.375 as often, bringing down his combat efficiency. "life" or "defense comes out as 1 over enemy(pen%*kill%*#shots)*friendly(mass-factor), which, in case of 100% killing shots, is just the mass-factor here of course.
With this as attack*defense=true performance the actual efficiency comes to:
PWI: 11.1%
CAP: 10.7%
LAV: 14.1%

That is essentially how much the GDI infantry tonnage measures up against the Barnbarian infantry tonnage, so virtually our ~2500 Troops are only about 280 to them at best. Their warriors have a 1:7 advantage, despite being only 2 attack and 2 defense techs, so about 2 TL ahead.

But then how come that despite even initial fortification disadvantage on top of all this 1:7 situation, the result still came out as this?:


The battle ended with a win for GDI, but: Infantry casualty rate: 97.8%. Nearly all light and medium buildings leveled. All supply vanquished. All but 21 of 240 light vehicles destroyed. 82% of medium vehicles destroyed. ...But, only 25% of heavy tanks.
Because, despite only fielding 24 heavy tanks, -that is a 60AR, 60HP, MAV+MAC unit-, these were responsible for a disproportionate amount of the killings and definitely all standing power, which turned this abysmal setup around into a win. And given Aurora's mechanics, this is absolutely no surprise. Doing the offensive performance metric once more:
A MAV in this setting is a 1x(32AP 32DMG) weapon, which clearly means each hit will 100% penetrate and kill. Too much actually, but the tank isn't meant to just engage infantry after all.
The MAC is a 3x(24AP 16DMG) weapon, which also happens to penetrate and kill on every hit, giving it a grand 300% performance here.

With this, even considering that such a heavy vehicle could be replaced by nearly 20 PWI soldiers, its kill performance per PWI-mass comes out as:
100%x4/(116/6)=20.7%
That is decent, but actually below even CAP infantry in raw damage. The question however is "who can maintain fire/performance longer?".

So for a final conclusion, we need to get the defensive standing power in there too. Before this was easy to measure, since every infantry unit was a leaf in the wind to the Barnbarian Warriors, who would kill in one shot, whether they used an anti-vehicle weapon, PWI, Barnklets or their pinkies.
For the Mammoth Tank you now have to differentiate between Warrior and Anti-Vehicle-Team. With their Anti-Vehicle having 1x(24AP 36DMG), their kill chances come out as this:
PWI: 0.25%
LAV: 5.8%
Note: The LAV is actually 2.2% if comparing on the PWI-mass basis. The enemy already has his troops on the field and doesn't care about relative unit efficiency anymore, so he doesn't need to factor this in. To get to a number that reflects actual expected outcomes between two unit types, only absolute shots/turn and pen%*kill% count.
So if you do a direct calculation without mass factors that asks
"How many of them will die before mine does?", you do it like this:

With _f being friendly and _e regarding the enemy unit to compare to. Essentially you sum up all the kill-chances of your weapons per turn, and divide them by theirs, which yields the fraction of kills you do before them over time on average.
For this humble Mammoth Tank we therefore get:
vs Warrior: 160,000%
vs Anti-Tank: 6944%

Or expressed as total amounts, these mere 24 Mammoth Tanks actually equaled:
38,400 Warriors or
1667 Anti-Tank-Teams.

..Well, they only had 2700 and 75 respectively, so there is your explanation for the win.

Of course, this basically operates on a 1v1 calculation, while realistically the enemy will do much more shots for every of yours.
You can factor in at least the fraction of mass between your troop type and theirs, to get a more fair comparison of the two.
So if you'd ask "How much troop tonnage can I destroy, using type X against type Y?", you'd correct the other formula with the mass-fraction term of course:

For that then you find that every Mammoth Tank destroys:
~83 times its mass in Warriors
9-10 times its mass in Anti-Tank

If you'd apply the mass term squared and measured against your own PWI, you could now also have a direct formula for troop vs troop efficiency in your own ranks, but I think it is pretty obvious by this point where that would lead to. The tank is not even 20 times as heavy as PWI, only about 7 times as heavy as the best infantry type, LAV, and still beats their performance by factors of x67-x750.
That is x9 to x39 on a per mass basis.
Calculation shows they are pretty much exactly x4 as costly as PWI and LAV per mass, but mixed with efficiency, you'd still be at x2+ to x10 'bang-for-buck' efficiency.

Also, remember, the enemy here is 2 weapon techs above GDI armor, so the tanks should be suffering more than other types, yet excel still. A competitive tank will be even more threatening.

A side note on hit-chance: You might know that heavy vehicles suffer from a greater to-hit chance, which would lower its defensive performance and thus efficiency by x0.75. However, this only applied as long as the unit is not fortified. The difference is not large enough to really count, and vanishes once the first construction cycle passes.(given you have at least some infantry or constructors surviving) Perhaps invasion tactic should be be to always land troops right before a construction tick. Cheese
Later, infantry might also catch up a bit, since they can receive more fortification in total, gaining 50% defense over vehicles instead of just those 33%. Still definitely not enough though.

Ground combat mechanical source
Now discussion the consequences of these findings. Obviously, if a tank, build for mainly an anti-tank role, is still more effective against Infantry than even Infantry, there is little reason to use anything else. If an anti-tank-team with technological advantage can't measure up to an old tank in the choice of weapons, then:
- The enemy has tanks. You counter with tanks
- The enemy has infantry. You counter with tanks
- Tanks, everyone

The obvious root for this, idk. "issue?" (I kind of like it though ), lies within the damage formula that heavily punishes insufficient penetration or damage, and rewards you greatly exponentially if you can push your enemy in the position where he doesn't have enough of that.
Since AP and dmg are very correlated, and somewhat less AR and HP are too, the formula (AP/AR)^2*(dmg/HP)^2 that determines the true hit, virtually shortens to (attack/defense)^4

For example, just taking GDI Trooper avg AP and dmg 9 against avg AR and HP 15.5, gets nearly the 11.1% using just the short formula above. One tech level further, and this is 25%, more than double, despite only improving by 2AP and 2dmg, but also only because they merely fight infantry.
Against a proper tank, the Troopers would again do no better, because the armor difference evidently strikes down even from higher weapon tech levels.

Everyone who makes use of this crazy run-off effect will be the new Sun Tzu. The system heavily incentivizes to use the biggest guns, and the hulkiest hulks you can weld together, because every bit of lacking armor or firepower comes with a fourth power drop in efficiency.
And that almost always makes up for whatever extra cost or mass those hulks would come with, unless you really outtech the enemy, at which point you would still want maximum armor, but might consider using some more rapid fire guns if even those already guarantee 100% kills.

So if anti-vehicle weapons dominate anti-vehicle combat, but they also dominate anti-infantry combat, and armor needs to be as high as it can get, then the conclusion of what you should always do to win is obvious:

All hail the Mammoth Tank. (..until something bigger and badder comes along that is)


I still play for RP though, so I only care for all this out of technical interest. That is why the formation there has medium vehicle tanks and "APCs" after all, the later of which suffered nearly 100% loss due to being lightly armored for no reason but RP. I do however still always cheer when my land battleships rule as they should though.

[Foxxonius Augustus (OP)]

I am loving the discussion so far! Acknowledging RP is king while also bringing anecdotes and math* in as well is exactly what I was hoping for. Bonus, most of what has been covered so far has broadly reinforced what I was already planing. I am interested to see that no one has mentioned Heavy Anti-Vehicle or Heavy Auto-cannons yet. Are they just wasteful overkill? To costly for their usefulness? Are they not being considered so as to be more fair to the AI?

As an additional sub-topic for this discussion, what are peoples preferences for medium command vehicle secondary armaments? Is it used as a spot to dump forward fire direction in case you ever use it? Do you just pick the lightest option and keep them on avoid combat? Do you give your command tanks a big auto-cannon and let your generals cover themselves in glory?

(* My subject line was intentionally trying to imitate the style of academic paper titles and with math that detailed it is quickly turning into one and I love it. )

[nuclearslurpee]

Ground combat mechanical source
Now discussion the consequences of these findings. Obviously, if a tank, build for mainly an anti-tank role, is still more effective against Infantry than even Infantry, there is little reason to use anything else. If an anti-tank-team with technological advantage can't measure up to an old tank in the choice of weapons, then:
- The enemy has tanks. You counter with tanks
- The enemy has infantry. You counter with tanks
- Tanks, everyone

The obvious root for this, idk. "issue?" (I kind of like it though ), lies within the damage formula that heavily punishes insufficient penetration or damage, and rewards you greatly exponentially if you can push your enemy in the position where he doesn't have enough of that.

[...]

Everyone who makes use of this crazy run-off effect will be the new Sun Tzu. The system heavily incentivizes to use the biggest guns, and the hulkiest hulks you can weld together, because every bit of lacking armor or firepower comes with a fourth power drop in efficiency.

I would highly caution against drawing strong generalizations from this analysis. On one hand, it is important to realize that going up against a spoiler race will give atypical results compared to going up against a normal NPR - critically, normal NPRs tend to use basic infantry and not a lot of power armor or genetic enhancement soldiers, so the analysis shakes out very differently. On the other hand, in this analysis there has not been much said about overkill effects which play a significant role in the "optimal" force composition. In this case, for example, if LAV or MAC prove sufficient to score the optimal kill rate, then MAV or HAC would represent significant overkill - which means bringing extra tonnage that accomplishes nothing for the battle at hand, and spending excess GSP to fire those heavier weapons repeatedly and with great vigor. This means that on the contrary, the system does not favor using the heaviest guns in general, rather the system favors using the smallest gun that will cleanly overmatch the target(s) where possible. This is the reason why you see players like Jorgen who will use CAP type weapons in the beginning of a battle to kill off enemy infantry, and move up the anti-tank guns later once their primary targets are heavy armor, to avoid wasting expensive AV shots on cheap infantry units.

There are also important strategic considerations here. It is true that, ton-for-ton, the most armored unit is the most effective in general. However, ton-for-ton is usually not the best way to assess ground units, in fact usually the build cost is as much if not more substantial as a factor. a VEH type with medium armor (4x) will cost 4x as much to build compared to an infantry unit or a 1-armor STA unit , which means you can field 4x as many infantry or static units (by tonnage) compared to heavy armor. Due to the fact that Aurora ground combat accurately models Lanchester's square law, a 4x number advantage comes out to a 16x combat advantage, which neatly equals the advantage of medium vehicle armor (4x armor, squared, also gives a 16x advantage).

This leaves two factors to consider. One is hit points, which unlike armor you do not have to pay any premium for (aside from the base class tonnage cost which is fixed). Here, VEH generally does have the advantage over INF, but it is not very clear in practice as INF units can make up for this by having the best efficiency of weapons to total size and the most favorable ratio of tonnage lost per unit killed, both very key mitigating factors.

The other factor at play is the over/underkill mechanics which tend to favor lighter units: in short, since heavier weapons cannot exceed 100% efficiency against INF or other light units, they are proportionally more effective against heavy armor even if they do not overmatch the armored units. Consider: against an enemy of equal tech, VEH with medium (4x) armor has the maximum efficiency benefit compared to INF with basic (1x) armor when facing PW or CAP weapons: INF will die every time it is hit, while VEH will die once for every 256 hits (although each lost VEH is a greater proportion of the force than each lost INF, so the actual ratio of tonnage lost will be probably closer to 1:50 or so). However, if the enemy is using LAV weapons, each hit on an INF unit still scores one kill with complete efficiency, however, the armored vehicles will suffer one loss per ~9 shots, with an actual tonnage loss ratio closer to 1:2 or so. Given that the armored vehicles cost 4x as much this is not so acceptable, and demonstrates how even the lighter weapons can inflict unfavorable losses against armor despite not strictly overmatching.

In practice, most NPR armies tend to be heavy on infantry and PW/CAP types of weapons, so heavy armor with a lot of anti-infantry weapons (CAP, AC) does tend to be optimal. However, it's not embedded into the mechanics that heavy armor and heavy guns are naturally optimal, and this can be a particularly costly mistake to buy into if you ever play games with multiple player races where a race might choose a force composition that upsets the usual dynamics and you must be ready to adapt your own strategy or suffer many costly defeats.

[nuclearslurpee]

I am loving the discussion so far! Acknowledging RP is king while also bringing anecdotes and math* in as well is exactly what I was hoping for. Bonus, most of what has been covered so far has broadly reinforced what I was already planing. I am interested to see that no one has mentioned Heavy Anti-Vehicle or Heavy Auto-cannons yet. Are they just wasteful overkill? To costly for their usefulness? Are they not being considered so as to be more fair to the AI?

Heavy weapons are usually too costly in tonnage, build cost, and GSP use to be generally useful. I would only use them for roleplay reasons or if necessary to counter the enemy threat, and NPRs don't usually get into the heavier vehicle types so the heavy weapons remain generally unimportant to me. In multiple player faction games, this is a huge advantage of deploying heavier vehicles, which are not usually the most cost-effective units but can force the opponent to expend far more resources to deploy counters everywhere just in case.

As an additional sub-topic for this discussion, what are peoples preferences for medium command vehicle secondary armaments? Is it used as a spot to dump forward fire direction in case you ever use it? Do you just pick the lightest option and keep them on avoid combat? Do you give your command tanks a big auto-cannon and let your generals cover themselves in glory?

Usually I just put a CAP because it is light, and use Avoid Combat. Some people put FFD on command vehicles but I think usually you want several FFD in a formation but you only ever want one HQ unit, more than one is sub-optimal unless done for roleplay reasons.

[Jorgen_CAB]

Nuclearslurpee are quite correct... there are little to no correct way to build an army... the issue with the AI is that it is predictable. The AI probably should mix it up with more template of ground troops to choose from and not make the NPR so infantry focused all the time.

My garrison forces usually is a healthy mix of PWI armed infantry and Static units with CAP/LB/LAV/MAV/HAV to support them. Usually the MAV/HAV is in their own AT-battalions and sit in the rear unless the enemy attacks with lot's of vehicles. Each division of garrison has three garrison infantry regiments (infantry and static units), two AT-battalions (Static with MAV/HAV) and the division HQ with artillery, usually MB as I gove artillery brigades to corps for long range fire to support the divisions. Each division is about 100kt in size, each regiment about 25kt in size.

As I played my fair number of multi-faction campaigns over the years I know that with diversity also comes unpredictability of outcome.

A formation mix of infantry and static units with heavier weapons will easily win over an equally costly only armoured tank force attacking even with no major defensive bonuses, especially if they use only heavy weapons.

When a force spent all it's GSP their hit rate drop significantly... don't remember if it is eight times or four... but it is enough that GSP use in a battle will matter if the battle is remotely even. We have to remember that GSP also has a cost and also have to be counted.

[Vandermeer]

It seems there is still some doubt about the numbers involved and the arguments made have not been understood as I intended.

Before doing numbers again, first this part:

On the other hand, in this analysis there has not been much said about overkill effects which play a significant role in the "optimal" force composition.

I am actually quite offended to see you believe that I wouldn't know about overkill mechanics and topple the analysis on this assumption without trying to understand what I really meant to say beyond the superficial surface. I am pretty sure I also acknowledged the overkill of the anti-vehicle cannon for example, so that should have tipped off that I had reason to consider this a good choice despite going overboard.

One major reason is that "optimal force composition" is dubiously defined. Sure, you can set out to tailor a whole army around countering one specific unit type, in which case double MACs would have done it in this situation. As you described yourself however, this spoiler battle was a quite atypical encounter, and the army doesn't exist to just fight infantry but be applicable under many circumstances.
Because, what would have happened, if they actually had some medium vehicles somewhere? Infantry would have lost even more of their efficiency, while the big tank gained relatively due to the MAV coming into focus.

So, I didn't claim anywhere that the design itself was "optimal" for this specific encounter. I meant as a general philosophy of what constitutes "optimal" combat troop spending, you will be surprised to find that the heaviest vehicles, who ostensibly are mostly outfitted for an anti-vehicle role, are actually also more efficient at an anti-infantry role as what you would otherwise think of anti-infantry: CAP structures, light vehicles or other infantry.
Can you have a better anti-infantry tank? Yes, of course. But will a dedicated anti-infantry tank show great efficiency against all possible encounters? No, but the anti-vehicle one surprisingly does, thus that is "optimal" as an actual building philosophy.
I feel like I had to spell the obvious out or counter nitpickery. As if I'd really claim "shoot sparrows with cannons". ...Well, I do, but for other reasons.

In this case, for example, if LAV or MAC prove sufficient to score the optimal kill rate, then MAV or HAC would represent significant overkill - which means bringing extra tonnage that accomplishes nothing for the battle at hand, and spending excess GSP to fire those heavier weapons repeatedly and with great vigor. This means that on the contrary, the system does not favor using the heaviest guns in general, rather the system favors using the smallest gun that will cleanly overmatch the target(s) where possible.

This was a further explanation to that point you made above, but I really wanted to nail on the conclusion "This means that that on the contrary, the system does not favor using the heaviest guns[...]"

When I presented that the combat efficiency of a design boils down to practically this (pretty accurate) simplification:


...What I really meant to express is this relationship:

That is: As long as you do not penetrate and fatally wound an enemy, gaining extra AP or DMG or both will give you a fourth power increase in efficiency.
However, if you overkill the target by firing at it with weapons too massive, your efficiency only drops linearly.


(Note: AP can never be higher than AR and DMG never higher than HP here of course)
That is what the mass factor (m2/m1) is about. If your design becomes say 25% heavier due to using too large a weapon on the target, its efficiency drops to 80%, because you could have used lighter weapons, and brought 25% more firepower.
However, if you ever step into the territory, where you don't kill or overkill the target, the efficiency drop will be incomparably more punishing than on the other side of that equation.

As a consequence, whatever inefficiency results from overshooting against infantry or smaller vehicles and structures, is vastly(=fourth power) outdone by the incredible gain in efficiency against all heavier types.
(In terms of the diagram above you can think of it having multiple red graphs stretched somewhat to the right of it, representing all heavier unit types. The biggest sum of efficiencies is gained by going to the rightmost 100% efficiency point.)
Thus the question "What is the most effective/optimal?" is answered by going big and not looking back.

This is what I meant to say from the beginning, but was very misunderstood.


And, of course, if you really see only a tiny fraction of enemies using heavy tanks themselves, then their counter (=HAV) is somewhat wasted tonnage overall, and not optimal. On a vehicle that is already 140 tons (hvy+HAC+MAV), an additional 16 tons from upgrading MAV to HAV however only constitutes a drop in efficiency of about 10% against all smaller types (m2/m1). But lets calculate the gain against heavy tanks for short:
MAV has 2/3AP and 2/3DMG of equal tech heavy armor and heavy HP. Therefore:
MAV efficiency: (2/3)^4 = 19.8%
HAV efficiency: 100%

..So if you can justify a fivefold increase in combat effectiveness against heavy tanks by your in-field demands, then the -10% everywhere else might be worth it. I would do it in hypothetical anti-player scenarios already, just to be sure my units have no counters, but yes, due to rare use of NPR heavy tanks, you might be fine with MAV and HAC, but just because the AI is also doing RP like we do and doesn't actually invest in the strongest choice all that much.

Remember though, very crucially: This is against an equal tech opponent, and often, especially in the early game (just as in the described scenario), the enemy will outrank you in tech, and therefore armor and HP. Having guns around that shoot way above their intended role, turns those units in veritable "high-tech-killers". Again, thanks to 4th power mechanics.
In short the system "does in fact favor the heaviest guns", or it at least does it to the point where you achieve 100% kill rates against the vast bulk of enemy unit types. In all practical purposes of the average Aurora game and their game-time, this will still result in, again, the heaviest guns being the best. (but HAV falling off first once you have late mid-game)

There are also important strategic considerations here. It is true that, ton-for-ton, the most armored unit is the most effective in general. However, ton-for-ton is usually not the best way to assess ground units, in fact usually the build cost is as much if not more substantial as a factor. a VEH type with medium armor (4x) will cost 4x as much to build compared to an infantry unit or a 1-armor STA unit , which means you can field 4x as many infantry or static units (by tonnage) compared to heavy armor. Due to the fact that Aurora ground combat accurately models Lanchester's square law, a 4x number advantage comes out to a 16x combat advantage, which neatly equals the advantage of medium vehicle armor (4x armor, squared, also gives a 16x advantage).

I like that Aurora does think about these things, like it does with ship armor geometry, but this is improperly implemented this time.
Maybe I am the one to misunderstand what you are saying here, but if I compare medium vehicle with medium armor to 1-armor infantry, I see that the actual advantage of the medium vehicle is 4^4=256, because it has 4xarmor and 4xhp. Plus, again, you can just go even higher and use heavy vehicles, who also only cost x4, but provide a 6^4 protection enhancement.

I calculated everything on a cost basis in the post above as well, coming up with a strong net positive x(>2)-x10 cost factor efficiency. (depending on vs LAV or PWI) And again, those guys' weapon tech outranked my armor tech, which led to a 1:7 advantage against my infantry, but against tanks, ..still this.

Here, VEH generally does have the advantage over INF, but it is not very clear in practice as INF units can make up for this by having the best efficiency of weapons to total size and the most favorable ratio of tonnage lost per unit killed, both very key mitigating factors.

No, infantry for sure does not have the most favorable loss rate.
The case where infantry assumes the role of least losses is only when you are so severely outgunned/out-teched that the enemy fire approaches the 100% kill ratio on your armored vehicles. ...Which probably is an observation that gave birth to this myth, since early skirmishes can be that way if you get raided.
If you we are talking about losses/damage inflicted however, then infantry won't even compare in these scenarios.

Just comparing CAP infantry again against 2xCAP medium vehicle with medium armor. Let's assume the enemy weapon has exactly 100% kill-per-hit ratio on the infantry, then
inf-CAP loss: 12 tons / hit (or hit/counterfire, since counterfire = 1 as standard)
mveh-CAP loss: 42 tons / 256 hits = ~0.16 tons / hit
Of course, that vehicle has only 2xCAP on those 42 tons, so since the infantry needs 24 tons for the same, you can correct this by virtually assuming 42/24=1.75 more hits on the vehicle over the same time, making it virtually:
mveh-CAP loss: 0.29 tons / hit/counterfire

That is a clear factor ~x40 winner in survivability just in this scenario, and since the vehicle is only 4x times more expensive as its equal tonnage in CAP infantry (as you said), it comes out as a x10 cost effective option too.
(Also did the same calculation with LAV infantry against 2xLAV mVEH, and came to 16 tons/ hit-round loss against 4.5 tons / hit/counterfire loss. In that case, vehicles still survive better, but the infantry is ever so slightly more cost effective, but only due to specialization. Using even heavier vehicles will cancel this.)


Again, I can see where you come from when you fight with real anti-vehicle enemies (especially if of superior technology), who will of course be able to crack those vehicles relatively early, while taking much longer to kill off the infantry due to overkill. This results in the observation that infantry has more standing power, but really, that is an illusion, because standing power is not efficiency. Their linear gain in virtual hitpoints from overkill simply can't measure up to the towering disadvantage they receive due to 4th power ineffiency from not being able to harm the enemy ...no matter how long they try(almost).
You might think they do better, because they survive longer, but they are actually just dying the preordained slow poison death, while inflicting much less punishment in return on the invader. Standing time (or time in general) is worthless for efficiency measures if you don't do anything/enough in return.

That is what the hit/counterfire metric means, because real time in terms of combat is just "how much you do vs. how much they do". A factor that seems to be grossly overlooked here. In full form this gets you to the simple formula above.

So summarizing the result of this all shortly: If an enemy can destroy your 25kt garrison of vehicles, he will also be able to destroy your 25kt of infantry. He is just taking his time.
Better to get it over with quickly and take some with you if you ask me.(..or do RP)


-----
I wanted to do some more calculations of hypothetical nature to supplement the encounter report from the post before and show how heavy armor and mostly large guns always achieve the summarized best results. I ended up writing so much in response that I am not only exhausted, but also feel that all the insights that would come from calculation examples are already expressed in distilled theory now. Maybe you can counter something first, then I would probably go into actual examples deeper if this wasn't clear, or I misunderstood here/ made a mistake.

I am interested to see that no one has mentioned Heavy Anti-Vehicle or Heavy Auto-cannons yet. Are they just wasteful overkill? To costly for their usefulness? Are they not being considered so as to be more fair to the AI?

In my case that was due to 2 factors: First, this came from a real game, and my tech level was just 10-8, at which point HAV and HAC are usually not available yet.
Second also RP again, because Mammoth tanks aren't actually the end of the arming spiral in this setting. There are even heavier vehicles, and what would you equip them with to make them feel extreme, if all the heaviest guns are already spend on 'small' tanks?

That, and as described above, HAV might actually be "too big" here once you have competitive tech, because the best gun is one that kills X*100% of all the enemy types you can find. The HAV is just the first gun to cross that backwards looking ineffiency boundary, but as your tech advantage rises, other gun types will follow.
In a practical game, this circumstance will not happen unless you sink, idk. 100 hours(?) into it (I play on 25-50% tech speed, so hard to judge), or turtle and wait early on to get higher tech before meeting the galaxy.

[Jorgen_CAB]

I understand that sometimes you might want the overkill to be very sure you can kill something... especially if it is higher technology... it might be your only option to be certain. But it is still less efficient if you have a good overview of the enemy tech and unit types.

If you are at tech parity the infantry can be extremely effective, especially together with other types of units and certainly in defence.

Let's take the heavy tank, tank killer of Heavy Vehicle with two Heavy Anti-vehicle cannons. We are completely ignoring size here as that is not important for defence at all only for planetary assault and sometimes not even there. We just assume 10/10 in armour and weapon tech for simplicity.

Anyway... the tank cost 15.84 Vendarite to build with 60 armour and hit points... there tank fires twice and expends 36 GSP per ten rounds.

An infantry with light anti-vehicle weapons cost 0.32 Vendarite with 20 penetration and 30 damage... 36 shots is need to kill a tank... 6 GSP per ten rounds

You get 49 infantry for one tank... but the infantry will use more GSP to kill the tank per ten rounds but they will quickly kill the tanks for the same cost even when you calculate the more GSP used. One infantry who carries 100 GSP is 0.2 Vendarite, so you can just remove a few infantry with weapons for ones that carry GSP and cover that cost.

If you also include some infantry with light personal weapons the tanks will fire half or more of their shots on them and the infantry will win even more. That single tank only get to fire twice per round while the infantry get 49 shots for the same build cost.

It is almost always better to have a cheap unit just underperform and getting overkilled in return in terms of efficiency, that is just the way it is.

The only real benefit of the tank is if you are up against something bigger or you have limited space and need as much firepower as space would allow, which sometimes can be important.

[Jorgen_CAB]

I would also add that you can not only compare one on one either because infantry works best when combined with static units or vehicles which can use heavier mounts too. Static is also good against other infantry too. Static units protected with especially PWL infantry is very effective as the PWL infantry buy time for the static to do the damage whatever it is, infantry or vehicles.

You should do some tests to verify this, but I have played enough multi-faction campaigns to know how effective these garrisons can be... and you need special anti-garrison troops to crack them without braking the bank and that certainly is not heavy weapons but weapons that is good against infantry and static units. Otherwise your force will get shredded badly, it still will.

The most effective unit at killing garrisons are a combination of medium tanks and genetically enhanced infantry with lots of CAP units and infantry with LAV and tanks with CAP and Auto Cannons. Still... a well crafted garrison with lots of bombardment, LAV and AT battalions CAP pillboxes etc... will be a hard nut to crack and you will suffer horrendous losses if you are not completely overwhelming them in numbers. Both light and medium artillery is quite effective against garrison troops of this kind, heavy bombardment is just overkill for this.

The thing is that different units can protect other units in different ways... tanks are great if the enemy have little to no anti tank weapons as they protect your infantry by drawing enemy infantry fire. Infantry protect the tanks against the enemy heavy weapons.

Therefore... if you don't know what you will face it is best to use a well rounded force so that you can decide on the battlefield which units you will deploy on the line of contact. If the enemy is easily destroying your tanks, then withdraw a large part of them and have your infantry soak up the damage, leave enough weapons to deal with the main type of the enemy force. That could be tanks mostly armed with CAP and auto-cannons for mostly enemy infantry or anti tank vehicles against tank heavy enemy forces. If you find that your infantry is slaughtered fast but your tanks seem to get no damage then withdraw some of the infantry and continue fighting with the tanks and any infantry with weapons that do the most damage. If the damage is evenly distributed from a size perspective then you can just leave things as they are.

[M_Gargantua]

I do love ground combat and combined arms, but the mechanics do really push you to min-max. One of the big things in ground warfare has always been about how infantry are a core part of maneuver. Without infantry screens tanks are easily ambushed and overwhelmed. Without heavy weapons support infantry are easy pickings for enemy fires. So you want a flexible force composition with many capabilities to adapt and use the best tools for the job.

So I had a thought about this and ran a test -

15/15 Tech levels for both

1x Titan UHV - UHVA - SHAV, HAC, HAC, HCAP
Weighing in at 460 tons at a cost of 110.4
171 Supply, no additional supplies.

vs

10000 Infantry

6000x INF - LIA - PW
3000x INF - LIA - LAV
1000x INF - LIA - LOG-S + Avoid Combat
Weighing in at 88000 tons and costing 1760
with a resupply cost of 6000*1+6*3000 = 24000 GSP and 100,000 GSP to spare.

Over the first 15 combat turns, the LAV infantry got 794 hits and 27 armor penetration hits (The PW did nothing ever)
in that same time the Titan managed to kill 1 PW Infantry and 1 LAV Infantry

At this point the Titan finally ran out of Supply, with the Infantry having gone through 282 supplymen (28200GSP) with 718 remaining and 100% Active supply.

Over the next 25 turns, The LAV Infantry got another 1241 hits and 23 penetrations.
The titan managed to kill 4x PW Infantry

I set the Titan to Frontline Assault at this point

Over the final 10 turns the LAV hit 1670 times and got 34 penetrations, and on the final turn managed 11 penetrations in one.

The titan did get resupplyed from being on home-ground which may have skewed it slightly.

In the end the Titan cost the assaulting army nearly 1.5x its cost and 15x its transport tonnage. This was from all the LOG-S Infantry being consumed. This all felt very wrong in the way it played out. 400 hours is too long for a single unit to last against the flexibility of infantry, and 6 infantry is far far few losses against such a level of firepower. In the end all the meaningful losses came from the sheer length of the battle due to the logistics draw of the assaulting infantry.

Overall I think there are two gameplay factors playing into why this result feels odd and could be improved:

1) 6 Infantry casualties? This is down to Heavy weapons failing their too hit rolls on infantry. They don't have splash damage, so its always HAC/SHAV etc vs a single unit, and if they evade, they dodge the whole thing. a HAC at these tech levels has AP 75 and DMG 30, vs an Infantry's 15 AR and 15 HP. That is a good level of overmatch. Unless the infantry rolls a save they really should still take splash damage. At such an overmatch like that they should maybe only have a 50% chance of surviving a "miss", let alone a SHAV at 135/135! Sure you make the evade roll, but a SHAV is a massive weapon, and it hitting nothing but air is counterintuitive. You would set a floor at 5% (the classic D20 critical save) of course. But a gun that big I'd expect some damage result even on a miss, if not three or four additional splash damage rolls against surrounding units. VEH and up would probably be immune to splash for anything less than SHAV/HB/SHB in this system, and SHV/UHV would be naturally resistant unless there is a big tech level disparity. This would have increased the number of infantry losses as expected.

2) While 6 infantry is far too few losses for 400 hours of combat against a dangerous weapons platform, equally 400 hours was far too long for anything to have been expected to survive. Units on a frontline assault role should count toward some sort of "Overwhelm" bonus -  A unit being 'Overwhelmed' would be reducing its effective Armor, and I think logarithmically scaling would work. Mechanically by buffing frontline assaults' AP, probably. Here we had a 10000:1 advantage, and maybe that correlates to a 40% buff to the assault AP. With 1000:1 being 30%, 100:1 being 20% buff, and 10:1 being 10%? That would really benefit combined arms where surviving infantry have a roll in helping to overwhelm remaining defenders. This would have reduced the timeline to <40 hours, and substantially reduced the number of LOG-S consumed.

[Scandinavian]

"Splash damage" is applying a tactical concept to what is an operational model. "Evasion" at the scale Aurora's combat model operates on is less "dodge this" and more "your princess is in another castle." And "fortifications" can equally well mean trench lines and bunkers or camouflage and redundant fixed infrastructure with multiple fallback lines. After all, it doesn't matter how much you overkill that bunker if it's empty because the guys manning it fell back to a secondary position.

So your titan vs. infantry fight isn't a stand-up fight where the infantry lines up in a nice, Napoleonic formation and does a Picket's Charge against the titan. What it describes is a heavy vehicle with no fire direction tromping about the landscape inflicting a bunch of collateral damage but only occasionally lucking into hitting actual military targets, while the infantry spends most of its time and energy staging ambushes, scouting attack and retreat routes, and generally making sure it's not where the big guns are pointed.

Probably your titan actually broke down less from getting hit by a LAV and more from a ball bearing wearing out somewhere, immobilizing it so the infantry could just crawl up on it and attach cutting charges.

There's a bunch of things Aurora could model in more detail - NCO density and quality in your formations and combined arms synergies being the two that come immediately to my mind. But "titan blasts a bunch of rear area supply depots, then breaks down under its own weight" seems like a very reasonable sort of thing to happen.

[Jorgen_CAB]

The problem with the titan is that it has such huge amount of hit points that no infantry weapon can really effectively defeat it... if you included just a small number of anti-tank vehicles they would have quickly killed it. The medium tank with two heavy anti-vehicle cannons will make quick work of any titan you deploy.

The light anti-vehicle weapons simply is too weak and which is why the infantry will burn so much GSP for no result unless you get extremely lucky.

In most of the armies that I have, even in multi faction campaigns I have moderate amount of anti-armour in combined arms units and then specific AT-battalions. The AT battalions are only brought in when there is lot's of enemy vehicles. Which in my campaigns there usually are as infantry is quite weak on their own. Infantry is mainly there to soak up anti vehicle shots.

From a RP perspective this usually turns military formation into quite realistic force compositions, so I'm happy with the overall result of how the mechanics works in general.

[nuclearslurpee]

From a RP perspective this usually turns military formation into quite realistic force compositions, so I'm happy with the overall result of how the mechanics works in general.

I think this is what people tend to miss with the ground combat mechanics. Ground combat in Aurora is designed to simulate at the operational and strategic level, not the small-unit tactical level that is ubiquitous in military science fiction. The granularity of ground formations is really more of a roleplay tool which mechanically supports this goal, albeit with a few cases that it still doesn't quite hit the mark yet but Steve improves the mechanics in every patch so it is getting closer with every release.

So at the tactical level, yes, the fact that a bazillion infantry can't take down one UHV Titan comes out a bit silly on paper, but at a force composition level this is not of great importance because a well-composed force should include heavy anti-vehicle weapons that will be able to counter a Titan formation. Of course, then a well-composed enemy formation would include lighter units to distract fire from the Titans... and so on, and so on, and the end result is a semi-realistic balanced force composition with considerable flexibility for roleplay, etc. under that umbrella. Which is why all of these tests that are like "I put 10,000 infantry against 20 super tanks" are not very useful at the end of the day - what would be of greater practical impact would be starting from balanced force compositions and evolving them in competition to seek a local optimum, but that kind of analysis is far more than I think anyone could reasonably expect to do for a game like Aurora.

Granted, against the NPR this tends not to work as well since the NPRs are infantry-heavy and don't adapt their formations or tactics, leading to trivially optimal force structures to combat them, but like most NPR problems in Aurora this is not a fault of the mechanics but rather the AI.