Brixia Mortars - Realistically Portrayed In Game?

[Vanir Ausf B]

I just did a head to head comparison of a US 60mm mortar firing direct lay vs one firing indirectly via FO at a point target. Range was 350m for both. 60s typically don't leave craters so I had to eyeball it, but there was no noticeable difference in dispersion. I would estimate that in both cases 80-90% of the non-spotting rounds landed within 2 action spots (16 meters) of the target.

I think I will test soft ground effects. I have an old US rockets test still on my hard drive that could be easily modified.

A decent thwack with an 81mm mission will definitely immobilise pretty much any armour in the game, though. This always seemed overmodelled to me.

IIRC this was reduced in the most recent CMFI patch.

[womble]

I just did a head to head comparison of a US 60mm mortar firing direct lay vs one firing indirectly via FO at a point target. Range was 350m for both. 60s typically don't leave craters so I had to eyeball it, but there was no noticeable difference in dispersion. I would estimate that in both cases 80-90% of the non-spotting rounds landed within 2 action spots (16 meters) of the target.

That's rather tighter scatter than I think I recall at that sort of range; were you testing with Regular/0/0 crew?

Yeah, the lack of craters really slows down testing the baby mortars; you can't just set them firing their entire complement in real time then go do something else, like you can 81mms...

IIRC this was reduced in the most recent CMFI patch.

"Small explosions cause less damage to vehicle tracks." Indeed you recalled corrrectly. I wonder what effect this will have on infantry close assault on armour (absent explicit demo charges)...

[Vanir Ausf B]

That's rather tighter scatter than I think I recall at that sort of range; were you testing with Regular/0/0 crew?

Yes.

I did another quick test. Same as before but range was increased to 1050m. The pattern was much more oval at this range, with about 80-90% of the non-spotting rounds hitting in a 80x20m area orientated along the y axis. I followed that with an identical test except heavy wind was added. The wind had a noticeable if undramatic effect, with the pattern spreading out to roughly 100x40m.

[Streety]

All of which apply on the range. Newlife has more relevant factors for differences between range performance of heavy weapons and their performance on the field of battle.

Well done, Womble, for trollishly pointing out that a later post by someone else added more factors to those I'd already listed.

I was merely helping to answer the specific question "Why should a bipod and base, sighted in, "heavy" weapon miss its aimpoint in combat?" And I did not explicitly exclude human factors - of course if under stress/attack themselves, all sorts of variation can occur such as knocking the mortar etc. But these things can also be modelled on the range, by the way, and mortars are not always under direct fire. But more to the point, I was referring to factors which effect a heavy mortar AFTER it had been successfully set-up and sighted-in - hence Newlife's points (though of course very valid factors in preparing the mortar to fire) don't really apply (as these are more to do with setting up and accuracy in attaining a sighting-in BEFORE firing) and his other comment about the ground is one of the factors I'd already mentioned.

If you want to go around trying to pick holes, I suggest you start with the one between your ears.

[womble]

I was merely helping to answer the specific question...

And I was merely pointing out that this was not helpful in answering the specific question of the difference, raised, once again, between range/training/exercise shooting and actual combat performance.

If you want to go around trying to pick holes, I suggest you start with the one between your ears.

So if I clear out the "hole" between my ears, I'll think better? Doubtful. Or are you just name-calling?

[John Kettler]

JasonC,

The casualty radius cited in the official War Department training film (Restricted) on U.S. Infantry Weapons "Infantry Weapons an Their Effects" is 17 yards. The treatment of the 60mm mortar begins at 12:55 here.

Regards,

John Kettler

[poesel]

More on mortar effectiveness in real life.

Thanks for the information. Now lets see how we can translate that into CM. Appendix B, B-3 f. says:

'Against a standing, platoon-size enemy unit, a 60-mm mortar section that fires five rounds per mortar should inflict about 20 percent casualties. If the enemy is prone, these fires should inflict less than 10 percent casualties. This means that a light mortar section's FFE should seldom consist of any less than five rounds for each mortar, and often will require more. '

Please help me fill in the blanks:

A platoon sized enemy - 40 men?

A mortar section has three mortars so 15 rounds fired - ok.

Prone enemy translates to 'hidden' units on open flat ground - ok

What would be the total area the enemy is occupying?

There's a note in the table above stating that the M49A is only 55% as effective as the M270. So the enemy would suffer 5.5% causalities.

This report assumes the availability of proximity fuzes. In B-5.b. it states that: 'Proximity fire is usually more effective than surface-burst rounds against targets in the open. The effectiveness of mortar fire against a prone enemy is increased by about 40 percent by firing proximity-fuzed rounds rather than surface-burst rounds.' Since we only have surface burst the % of causalities is reduced to 3.9%.

To put it in one sentence:

15 60mm mortar rounds fired on an area of x m^2 of open ground on 40(?) men with a hide order will cause on average 1.6 causalities.

So if someone could fill in the x for the area and confirm the 40 men then we have a test case.

[JonS]

75m x 75m (9 or 10 tiles by 9 or 10 tiles). Roughly.

[ForwardObserver]

Not shocking at all.

Certainly not to me. I used that adjective because I don't get why people are assuming the modeling of the light mortars is wrong, rather than looking at other CMx2 systems and mechanics (such as action spots, TacAI behaviors, player input granularity, tactics, etc.)

I think they've got the mortars modelled accurately enough. What is out of kilter is the way the TacAI moves its units and reacts to mortar/artillery fire. I think some fudging of the lethality of mortars is required to offset the Tac AI's inability to react appropriately.

Or perhaps making the TacAI to show a broader, more flexible range of behaviors. Such as running (forward or backwards) to get away from the area the shells are falling opposed to crawling.

That would be consistent with the quest for greater fidelity in the model that pervades the CMx2 engine. What you propose isn't yet...

This has already been done for tanks firing on the move. Because the Tac AI can't perform short halt -fire, we have overly accurate firing while on the move to simulate the short halt.

Very good point. Consistency in the engine doesn't seem to be a sacred cow for BFC.

Yet I don't like that 'fix' much. Tank gun fire is less accurate, indeed, but still accurate enough to make it quite useful. This allows fast AFVs - such as Shermans - to charge along oblique lines on the flanks of an AT asset, and a even a near miss can cause casualties/disable the gun. The tank can track and fire, but the AT asset can't track (and won't fire).

If I had been given the choice, I'd have gone for having the AFV TacAI to stop and engage targets for the Slow, Move and Quick orders. This may indeed leave AFVs in a bad position - e.g. non-hull down towards AT threats. But the responsability to assess hull-down - as well as LOS - is for the player, not the TacAI.

I'd be happy if mortars or artillery suppressed more but killed less. More suppression and reduced lethality. Maybe even link lethality to the target unit's experience. The higher the experience the greater and more rapid the suppression will be while Green and Conscripts get killed more frequently. I doubt that this will happen though.

Even if I don't like that much, it's indeed an option which would make things have an outcome more in line from expectations. No matter how different would they look from our expectations. And indeed, as a 'fix', is much easier than writing and testing new TacAI behaviors.

[Sublime]

I also think the mortars wouldnt be as glaringly noticeable as super killers if for example machine guns were more lethal, or at least worked more like real life. For example, the Germans have a plethora of HMGs/LMGs and they're fantastic ones at that. And one of their trump cards is their high RoF. I never see MG's fire at the rate of fire they could, even though it does increase quite a bit as range decreases. Yes I know that IRL they wouldnt burn through 2k rounds of ammo in one battle usually. However, CM isnt modelling day to day combat, as has been pointed out its modelling the once in awhile knock down drag out fights - all too often normal battles are a few squads vs a battalion crashing through after a preliminary heavy bombardment. Or whatever.

Point is even if MGs werent made deadlier per se, if the RoF was increased even by say 50% (within what the real weapon could do) I think we'd see a significant amount more casualties from them and also associated suppression effects. This would also help with the mortar vs infantry firing at them situation where the mortar will kick the infantries a$$ 4 outta 5 times. At least I think it would. would also be nice if the bursts were a little more randomized. Instead of computer efficient 6 round bursts or 3 round bursts every time it.d be nice if they could be 6, 9,6, 4,5,8, etc...

[John Kettler]

ForwardObserver,

Welcome aboard!

I emphatically agree with your views on the difficulty with modeling the short halt via firing on the move. From what I can tell, this does indeed screw those on the receiving end, in that they are continually penalized for engaging a moving target when it's really only an intermittently moving target. This was certainly my experience in the CMBN Demo, where Panthers not only ripped my defense apart while firing on the move, but also had an unholy ability to find LOS instantly, through the most unlikely paths, then conduct deadly fire. Meanwhile, I'm standing on my head trying to find something I can actually engage.

Sublime,

As the controller of the mortars, you can put in pauses and delay and/or stagger firing, thus limiting how many rounds get fired during the turn. Unless in FFE, this is perfectly realistic, since the time of flight is significant and corrections can't readily be applied until impact is observed. Despite standards, there will always be slight variations in crew performance, too. All those seconds and fractions thereof add up and vary from crew to crew. This is simply the nature of human performance, which is not absolute but may be bracketed statistically. Some people need more sleep than others, some are that little bit faster mentally, while others slog through the mental and written computations. Is the section leader completely head up and switched on, or is he dead tired, mentally befogged and slow to respond in general? Who's eaten and when did that last occur. Is one guy sick, while the rest of the crew is well? This can be iterated practically forever, but you get the idea.

On balance, I think if we get direct lay mortar fire lethality down into the credible range, via adjustments to cover effects, self-preservation instincts, delivery accuracy and such, then people will stop talking about and doing militarily insane things like running with mortar rounds already arcing through the air. I still have yet to see a single credible report of any troops doing this. In reality, the solution to this is mercilessly Darwinian: Idiots who run when they have mere seconds to dive for cover WILL be wounded or killed!

Regards,

John Kettler

[Vanir Ausf B]

I just tested US 60mm mortars. Setup is 1 FO calling in fire from 3 mortars. 3 overlapping area targets 40m in radius, Heavy/Quick. The center of the target area is about 335-340m away from the firing mortars. Inside the target area are exactly 40 German soldiers, Hiding on dry dirt. The Germans are Fanatic with +2 leadership to keep them from getting up and running. The Americans are Elite with +2 leadership to get as many shells on target as possible.

Any shell hitting within about 1 action spot of the Germans was counted even if it was a little outside the target area. Lightly wounded soldiers were not counted as casualties.

Test 1

Total round fired: 21

Counted rounds: 18

Casualties: 3

Test 2

Total rounds fired: 22

Counted rounds: 20

Casualties: 7

Test 3

Rounds fired: 21

Counted rounds: 19

Casualties: 10

Test 4

Rounds fired: 22

Counted rounds: 20

Casualties: 10

Test 5

Rounds fired: 22

Counted rounds: 20

Casualties: 11

Test 6

Rounds fired: 21

Counted rounds: 18

Casualties: 9

Test 7

Rounds fired: 22

Counted rounds: 20

Casualties: 13

Test 8

Rounds fired: 25

Counted rounds: 19

Casualties: 11

Test 9

Rounds fired: 22

Counted rounds: 18

Casualties: 10

Test 10

Rounds fired: 22

Counted rounds: 15

Casualties: 5

Total rounds counted: 187 or 18.7 per test.

Total casualties: 89 or 8.9 per test which is 22.3% casualties.

http://www.2shared.com/file/1Il6aSO_/Mortar_effectiveness_test.html

[Vanir Ausf B]

75m x 75m = 5625 m²

80m diameter circle = 5027 m²

So a little less but I counted shells that landed slightly outside the circle so I think it was effectively close.

[ForwardObserver]

Test 1

Total round fired: 21

Counted rounds: 18

Casualties: 3

Test 2

Total rounds fired: 22

Counted rounds: 20

Casualties: 7

Test 3

Rounds fired: 21

Counted rounds: 19

Casualties: 10

Test 4

Rounds fired: 22

Counted rounds: 20

Casualties: 10

Test 5

Rounds fired: 22

Counted rounds: 20

Casualties: 11

Test 6

Rounds fired: 21

Counted rounds: 18

Casualties: 9

Test 7

Rounds fired: 22

Counted rounds: 20

Casualties: 13

Test 8

Rounds fired: 25

Counted rounds: 19

Casualties: 11

Test 9

Rounds fired: 22

Counted rounds: 18

Casualties: 10

Test 10

Rounds fired: 22

Counted rounds: 15

Casualties: 5

Thank your for the tests. So on average 80% of the rounds fired fall within 8 meters.

The action spots relevant to the 9 teams in the picture account for a surface of 5184 square meters ( 9 x 9 x 64 square meters, each action spot). The surface of a circle with a radius of 40 m is 5,206 square meters.

If all rounds are supposed to be uniformly distributed within those 5,206 meters, hitting a relevant action spot 8 out of every 10 times, when the area occupied by those units is 9/10th seems to be perfectly normal.

Hence the conclusion is that the effect of a 60mm projectile detonating up to a distance of 8 meters is out of whack by about an order of magnitude?

[Michael Emrys]

Interesting.

Michael

[JasonC]

A good test, but to see the degree of actual overmodeling in CM, you need to put the point of aim *directly* on one of the squads in the target area. Not just nearby, expecting shot scatter to make them approximately the same. They won't be, the shells cluster so tightly that the point of aim being *perfect*, not approximate, will make a serious difference.

Any way you slice it, though, it is excessive men hit per round fired.

25 heavy shells - 81mm mortar, 105mm tube artillery, and larger (120mm mortar, 150 or 155 etc) in a mix of about 1/3, 1/2, 1/6 - fired per actual man hit, was a typical operational rather than tactical average performance, firing against men with field works for cover. Not prone in the open, to be sure, but not light mortar rounds either. Not fired on one occasion with the men deep in their holes, but spread over weeks of action with targets of all levels of exposure seen in typical combat with enemy infantry, using field fortification cover to the extent they could, to avoid the artillery fire.

And that rate of hits per shell was sufficient, on operational scales (weeks to a month or two, up to armies engaged) to bleed enemies white by artillery attrition, to the point where they could no longer hold a line.

Anything like an achieved hit rate of one man down per 2 light mortar rounds fired, and the war would have been over in less than a month, with everyone hit by then.

[Vanir Ausf B]

Second battery of tests. These are identical to the first except that the terrain the Germans are lying in has been changed to mud, ground condition has been changed to "muddy" and weather is "downpour".

Test 1

Rounds fired: 18

On target: 15

Casualties: 8

Test 2

Rounds fired: 20

On target: 18

Casualties: 8

Test 3

Rounds fired: 20

On target: 17

Casualties: 10

Test 4

Rounds fired: 19

On target: 17

Casualties: 6

Test 5

Rounds fired: 18

On target: 16

Casualties: 7

Test 6

Rounds fired: 19

On target: 16

Casualties: 6

Test 7

Rounds fired: 17

On target: 14

Casualties: 8

Test 8

Rounds fired: 19

On target: 14

Casualties: 9

Test 9

Rounds fired: 20

On target: 18

Casualties: 8

Test 10

Rounds fired: 18

On target: 15

Casualties: 3

Total on target rounds were 165 or 16.5 per test.

Total casualties were 73 or 7.3 per test or 18.3% casualty rate. This is slightly lower than the dry ground test because for some reason the total number of rounds fired and therefore the number of on target rounds were a little less. But the ratios are virtually identical: 1 casualty per 2.1 on target rounds on dry ground vs. 1 casualty per 2.26 on target rounds in mud.

I think we can safely conclude that ground conditions have no effect whatsoever on HE shell lethality.

[Vanir Ausf B]

Full disclosure: I do not own CMFI. These tests were conducted with CMBN:CW (1.10). But I would be surprised if the model is any different in CMFI.

[ForwardObserver]

Full disclosure: I do not own CMFI. These tests were conducted with CMBN:CW (1.10). But I would be surprised if the model is any different in CMFI.

It isn't. I have just done five tests and I'm getting between 20% and 25%, with similar parameters (mortars are at 400m, Elite/Fanatic everyone). The whole fire mission lasted for something like 2 minutes and a half, and a similar number of 60mm projectiles fell within the platoon footprint (random fluke or not, on average, just an average of 1.5 60mm shots fell outside of the circle centered on the platoon).

[John Kettler]

Vanir Ausf B,

Judging from your own screenshots, it appears you are firing a converged, rather than parallel, sheaf. To my mind, this is a bias in the analysis--unless the plan is to model an attack on a point target. The platoon, as deployed for the test, though, isn't a point target.

Don't know about you, but I'd be interested in knowing what happens to those hellish casualty rates when the training level and morale of the mortar crews start to drop. Is the ability to concentrate fire going to deteriorate? Is the pattern diameter going to increase? Will there be more outliers? If there are, will that increase or decrease overall lethality per shoot? Will the effects be more fundamental, as in a botched initial range estimation? Will time to range in go up? What about spotting rounds prior to FFE?

I know it's easy to ask, but it's much harder to run the tests. They take time, require considerable attention and compete with all the other things you need to be doing--such as playing CM! Still, I think it would be worthwhile to know.

Regards,

John Kettler

[Vanir Ausf B]

Judging from your own screenshots, it appears you are firing a converged, rather than parallel, sheaf. To my mind, this is a bias in the analysis--unless the plan is to model an attack on a point target. The platoon, as deployed for the test, though, isn't a point target.

Why is it biased? Biased towards what?

Don't know about you, but I'd be interested in knowing what happens to those hellish casualty rates when the training level and morale of the mortar crews start to drop. Is the ability to concentrate fire going to deteriorate? Is the pattern diameter going to increase? Will there be more outliers? If there are, will that increase or decrease overall lethality per shoot? Will the effects be more fundamental, as in a botched initial range estimation? Will time to range in go up? What about spotting rounds prior to FFE?

The thing about testing is that in any given test you want to eliminate as many different factors as you can instead of testing them all at once. That way you don't have to figure out which factors are responsible for the results. That is why when I tested dispersion I didn't bother with putting infantry under the shells to count casualties, and it's why I made the FO and mortar crews elite.

It is reasonable to assume that lowering crew quality will result in a smaller portion of shells hitting the target area. It is almost certain that a smaller portion of shells hitting the target area will result in fewer casualties. I'm not particularly interested in testing that right now because I don't think crew quality factors have much if anything to do with possible over lethality of HE in the game.

I know it's easy to ask, but it's much harder to run the tests. They take time, require considerable attention and compete with all the other things you need to be doing--such as playing CM! Still, I think it would be worthwhile to know.

I don't, at least not enough to be motivated to do it. But there's nothing stopping you or anyone else from doing it.

[Sublime]

Kettler- Im not sure what you.re getting at with the number of mortar rounds fired reply to my post. I was talking about machine guns.

You can alter the number of mortar rounds fired - through the indirect mission panel. Also target briefly in CMFI. Of course if you play real time you can very much alter it. Not so much in a PBEM. But I digress, I was talking about machine guns.

[Vanir Ausf B]

See in particular Appendix B on target effects planning for mortar fire.

http://www.globalsecurity.org/military/library/policy/army/fm/7-90/Appb.htm

Briefly, the casualty radius of the 60mm mortar round vs a standing man is about 20 meters. For the 81mm, it is more like twice that (35 meters, 40 with improved modern ammo but 35 for WW II).

Unless I'm looking at that wrong I think that is the diameter of the area of effect, not the radius. So the radius would actually be 10 meters.

In my testing I saw prone men regularly hit at much longer ranges. I measured one at 46 meters from the point of impact. In mud.

[dieseltaylor]

In my testing I saw prone men regularly hit at much longer ranges. I measured one at 46 meters from the point of impact. In mud.

Ouch!

However I have decided the temperature for the test must be below freezing and he was hit by frozen mud clods! : )

[c3k]

Unless I'm looking at that wrong I think that is the diameter of the area of effect, not the radius. So the radius would actually be 10 meters.

In my testing I saw prone men regularly hit at much longer ranges. I measured one at 46 meters from the point of impact. In mud.

I have never heard, or seen, of any effects being charted by diameter instead of radius. That made me look at the document. Figure B3, as you state, shows diameter. However, Figure B10 shows radius. It appears that B3 is wrong.

However, my conclusion is based on assumptions. Shrug.