Question on Penetration vs. Cover

[c3k]

Gents,

A statement in another thread caused a question to arise in my febrile mind. For that alone, I am grateful.

Does the cover given by some terrain vary based on the weapon firing at a unit in that cover? E.g., given a squad in a Heavy Building, will a 100 firepower attack by SMG's have the same impact as a 100 firepower attack by a .50 cal? Were I in that building, I know I'd much prefer to be getting fired at by SMG's.

In reality, a heavy building's walls would probably stop every 9mm round. (Assume some sort of solid masonry construction.) In reality, the Ma Duece could, and would, dismantle entire buildings.

Okay, I can live with an abstract, "a lot of 9mm rounds went into windows and ricocheted around and hit your guys" answer. CM is, after all, a game.

But, if the cover value were some sort of threshold which the rounds needed to overcome to have an effect, that would show the real benefits of a full powered cartridge versus, say, a pistol round.

Is anything like this modelled? Or is it just a straight percentage of cover yields a percentage decrease in firepower on target?

Thanks,

Ken

[SirReal]

Good question. Perhaps some experimentation will provide an answer.

Logically, rounds that can't penetrate should have no or very limited effect if a target in good cover is suppressed.

[Thin Red Line]

Originally posted by SirReal:

Good question. Perhaps some experimentation will provide an answer.

Logically, rounds that can't penetrate should have no or very limited effect if a target in good cover is suppressed.

Unfortunately canister shot effects on infantry in heavy buildings in the game prove it isn't modelled .

[Michael Emrys]

Yep, I think this kind of penetration was just too fine a discrimination to get included in the first engine design. Might raise the issue of it for something in the rewrite though. It all comes down to the amount of designing and programming time available as to whether it's more worthy of attention than other issues. Will its inclusion make for better gameplay than the other things that will now have to be left out because there wasn't time to do them all (and there never is)?

Michael

[Redwolf]

This kind of different effects of the same type of cover to various projectiles is not modeled.

I think it works reasonably well for the usual stuff flying around, 7.62 - 9mm bullets and fragments from HE shells. .50cal and 14.5mm shots are not too common in CMBB. 20mm usually shoots HE, so that works, too.

It works less good for canister shots which are rightly very effective against soldiers with few cover, but don't have their effectivness degraded enough when the target is in cover. Some exponential application of the cover value for canister would be in order, IMHO.

[JasonC]

Small arms fire is all lumped into a FP rating and treated the same. But there *is* a differentiation of cover effects against two types of attack. It just isn't done *within* small arms fire.

The two types are infantry FP attack, and HE. HE ignores the *concealment* portion of % exposure ratings. This is not meant to reflect *penetration* - shell splinters penetrate far less than rifle bullets do. Instead, it reflects the fact that infantry FP is *aimed*, while HE isn't. Light vegetation easily throws off aim (i.e. you can't see what to shoot at), but it doesn't stop either fragments or bullets.

This differentiates cover types against the two kinds of threat. E.g. A foxhole (cover) from a wheatfield (concealment), when both can give about the same % exposure rating. Against rifle fire either one works. Against a mortar barrage, only the foxhole helps.

[Redwolf]

Are you sure this is correct?

I agree that the exposure as displayed is supposed to be composed of seperate cover and concealment values.

However, I was assuming that actual damage computation was done identically for smallarms and HE, only taking cover (but not concealment) into account. From my assumptions so far HE works by applying its blast value as firepower value as if a squad was firing with that firepower from where the shell bursts.

[Michael Emrys]

Originally posted by redwolf:

However, I was assuming that actual damage computation was done identically for smallarms and HE, only taking cover (but not concealment) into account. From my assumptions so far HE works by applying its blast value as firepower value as if a squad was firing with that firepower from where the shell bursts.

I think BTS stated something like that way back in the early days and has restated it a couple of times since. Or I could have been halucinating that day.

Michael

[JasonC]

It does indeed translate the blast value into an FP value, based on the distance from the impact point. But the % cover it uses also ignores concealment. The printed "% exposed" number is fully applied only to infantry type FP.

Try mortaring a company in a wheatfield and another in foxholes (both around 44% exposed) sometime. You will hit more men in the wheat. It is quite noticable. Treebursts make the effect even more pronounced, for indirect HE compared to infantry fire vs. scattered trees e.g. Those are fine cover vs. infantry shots, but lousy vs. a fire mission.

[Redwolf]

Thinking over it, it would make slight sense to have concealment work as partial cover for smallarms fire, at least for bigger units like squads. That would model that some of the squad's men are not visible to the shooter and fire on them would be less effective, where HE doesn't care whether they are spottable or not.

But AFAIK this is not what CM does.

[JasonC]

AFAYK, but you apparently haven't tested it.

I've run many large scale tests of casualties typically caused vs. total blast and vs. total infantry FP.

I'm an attrition minded player. The exchange of my ammo for his men, or vice versa, tends to be critical to my overall plans. I want to know what levels of fire I can absorb without his ammo lasting to wreck my force, how favorable the shooting has to be before I can afford to open up myself against various targets, etc.

And I've found that the "exchange ratio" of blast to FP is typically 2-3 to 1. Blast is better - a lot better.

I typically plan on 200 blast causing 1 causalty It is actually not linear, and gets better than that for 155mm and up, but that is a second order correction. Closest range and most exposed infantry fire is also better than lots o littles. But under typical conditions, it takes more like 500 infantry FP to cause 1 under common conditions. Very low FP doesn't cause any to speak of, just morale dips that are erased almost instantly. These are very rough, but good enough for planning purposes.

Look at your units at the end of a scenario and multiply out their blast times rounds expended or their FP at the typical ranges they fired at times ammo expended. Divide by their recorded kills. Total for whole categories - all MGs and infantry vs. all mortars and FOs e.g. You will see it straight away. It is too large an effect to miss. E.g. HMGs mostly pin things, even light FOs both pin and get kills, etc.

That seems to be a pretty straightforward result of typical cover seen on average - which can be as good as 20% vs. infantry fire (mixed 25% scattered trees and 15% woods etc), more like 50% vs. blast. Before cover corrections, 1 fp seems to correspond (though messily, with variation as large as a factor of 2) to about a 1% chance of hitting someone.

Blast is typically facing higher % exposure numbers, aka lower cover numbers, because the total presented by the LOS tool is cover plus concealment, and concealment works against (aimed) infantry FP but does not do anything against (unaimed) blast.

You don't have to deduce it from averages, where a lot of other factors enter that you might think are varying all over the place. You can also see it with units with the same exposure numbers yet quite different outcomes against HE. Just let one form of cover include lots of vegetation while the rival form does not (brush or a foxhole, woods or a heavy building, trees or rough, etc). Try it.

[Patton21]

So you guys are saying that a 50 cal machine gun at 100 fire power has the same damage as a hurt infantry squad of 100 fire power assuming the machine gun and infantry squad are at the applicable distances?

[Redwolf]

Well, I did only rough testing and that indicated that [x] blast causes more casualties than [x] firepower. That is contrary to what BFC said hence I put it under statistical anormaly.

But that was a test with the target on pavement in both cases. So the different cover/concealment cannot be responsible for the casualty difference.

I did notice that first volleys firepower are notiably less dangerous than followup bursts. A single burst even from SMG squads at close (just above grenade) range doesn't do many casualties. It is the next bursts that do the casualties. Likewise, since HE shells seem to do less damage per shell than a full turn of fire. It is reasonably easy to see by shooting up some infantry with a 88, noting how man men the first hit cost and how many the first 10.

But then, maybe I was dreaming.

[ June 18, 2003, 12:42 AM: Message edited by: redwolf ]

[Robohn]

Pretty much that is true, 100 FP is the same all around. The thinking is that a casualty is a casualty (soldier too injured to continue fighting). Whether from a shell splinter, a 9mm SMG round, or a .50 cal hit. Yes, a .50 cal hit is more likely to kill a soldier than a 9mm hit, but all CM cares about is whether he is injured enough to be removed from combat. The .50cals and 14.5mm carry the benefits of being able to kill HTs and Light Tanks so I don't feel too bad about some of their other aspects not being modeled precisely.

[c3k]

Oh, my. It seems my beautiful thread is in danger of morphing into an examination of the differences between blast and firepower effects. To reititerate, I was, and am, curious about the differences in effect between different sources of FIREPOWER. (Although, admittedly, I learned something interesting from JasonC's post. Thank you.)

I ran a simple test. I created 4 separate firelines. The target end had a small heavy building surrounded by water. (Every man's house a castle - with a moat!) In each building I placed a German squad with zero ammo.

Then I placed the following units in the firing lanes: A Soviet '41 rifle platoon; an SMG platoon; a 14.5mm HMG; a 37mm AA gun (with HE ammo to zero - nothing but 200 rounds of AP - big bullets!).

I positioned each unit at a range such that they could put approximately 50 firepower on target. For the rifle platoon, I split each squad and put the LMG section out of sight. That way only Mosin-Nagants and SVT's were firing. The 37mm AA gun did not have a firepower rating. Again, it only had AP rounds.

After running the test a few times, I could not see any immediately apparent differences between effects. I _MAY_ have noted an increased morale effect on the target by the 14.5, but I'm not convinced of that. The 37mm AA did have a good effect, but, again, nothing that could not be within tolerance for random results.

I would've thought that there should be a decreasing effectiveness, in order; 37mm AA, 14.5mm, rifle platoon, SMG platoon.

If anyone wants a copy of the scenario and would like to run tests and apply some sort of analysis to the results, please email me at the address in my profile.

Ken

[Redwolf]

Ken, it is simple: there is no such model for different kinds of cover affecting different kinds of smallarms ammo in CM.

There also is no "so that only [x] and [y] weapons in the squads are firing", it is completely sunk into the abstraction, it is just a bit more or less firepower from the squad as a whole.