Artillery: bang for the buck

[Wreck]

By simple calculation using the QB price of arty, with its number of shells and their blast, one can determine that for the most part the total blast one buys every sort of arty module, is roughly the same price. That is,

is more or less constant, for most arty.


Exceptions are rockets, which are about 1.5x higher, and VT arty, which is about 0.75 as high as other arty.  


CM players with more than a few quickbattles under their belt, know that big arty is good, and often more effective than smaller arty.  A single 240mm shell, if lucky, can kill practically an entire platoon.  (I have had this done to me.)  Similarly, everyone who plays much CM will know that 81mm mortars are not very effective; even if the targets are in trees, 81mm tend to do little damage without prolonged shelling.


How can we account for these empirical observations, other than by suspecting that the "blast/buck" figures do not accurately reflect arty power?


I decided to try to test whether or not "blast/buck" reflects arty power.  


The testbed target range had three identical targets.  Each consisted of 3x3 rubble squares, with the middle one raised into a little peak (elevation 9) to make aiming very easy.  Into the 3x3 rubble I placed 20 American squads (240 men), each elite with 50% fanaticism.  I used 6 company commanders to control them, +2 in all stats.  (I did not want them moving and screwing up the tests.)  The pattern of squads was symmetrical in both left/right and front/back terms.  6 were placed on the outer edges of the rubble.  Another 4 placed down the "center line" of the rubble.  The remaining 10 were placed about halfway from the midline to the edge.


The firing batteries were 5 81mm spotters, 3 120mm spotters, and a single 240mm spotter.  The prices of these units are 71, 102, and 310 respectively.  So firing all of them except for about 50% of one 81 module is the same expense in "bucks" -- QB price.  That was the first test I ran.  


Here are the casualty figures for the 240 American targets:

It is quite obvious from looking at these results, that blast/buck does not capture artillery performance. Note that the 240mm was killing almost every American in the test area (there were 240 total, recall). This made me suspect that the performance results were being skewed by firing so many shells; after all if you are hitting dead men you get no more kills. Therefore I ran a second set of tests calibrated to the 120mm: I fired an entire module of it, 1.5 modules of 81mm, and 6 (of 18) shots from one 240mm observer. This is exactly 1/3 of the shots fired in the original set of tests. Here's the results:

The results are much as expected. The edge to the larger calibers increases in terms of kills/buck. Note, though, that the variance is higher, too, especially for the 240mm firing only 6 shots, of which one (or maybe two?) is a spotting round.

Lessons? Well, bigger is better for quickbattles, but only if all other things are equal. But we know they are not equal; in particular, the time to get fire varies considerably for various arty. This is why the larger mortars are so favored in quickbattles. But Americans, especially, with their speedy arriving big arty should seriously consider the largest calibers.

My speculation at this point is that actual shell effectiveness will be found proportionate to its blast squared. Using using blast^2*#shells/price yields a decent fit to the data at hand.

Blast^2 also makes sense from the point of view of simple implementations of arty blasts. If the implementation is that effect on a given unit of a given shell is proportionate to blast divided by distance, then blast^2 for the apriori effect is correct.

[Michael Emrys]

There is another more subtle factor to be considered in trying to calculate the relative usefulness of different artillery modules, and that is suppression. I don't always look to my arty to do much of my killing for me, but just to keep the enemy's heads down and maybe erode their morale a little until my infantry gets close enough to do the job. Because you get a lot more shots with the 81mm, it is more useful for this kind of work. I expect that you can also buy more smoke per buck with the smaller calibers too, though I have not tested this.

BTW, it would have been interesting if you had been able to include the 105mm and 150mm in your test, as well as the artillery of other nationalities.

Michael

[ 09-10-2001: Message edited by: Michael emrys ]

[Andrew H.]

To a great extent, arty effectiveness depends on what kind of troops you're facing and what kind of battle you are fighting.

If you are fighting against troops that are dug in or in buildings, you probably want something more than 81mm mortars. If you are defending, or fighting a ME, 81mm mortars can be quite effective, at least against green or regular troops, which is what I tend to play). An 81mm mortar barrage against regular troops advancing in the open will generally stop their advance, and often send them cowering back to the cover from which they came. (Green troops will usually go back to the cover from which they came). Two turns of 81mm mortars on troops in trees may not cause massive damage, but with greens/regs, it will usually disorganize them for a couple of turns.

Larger arty would, of course, do even more damage, but the delay is so great that it would be pretty difficult to hit a specific attacking platoon soon enough to break up the attack.

Plus, it's a no brainer to quickly switch between smoke and HE with an 81mm mortar. I would be much more reluctant to do the same with expensive 155mm arty.

[Wreck]

<BLOCKQUOTE>quote:</font><HR>

[suppression] I don't always look to my arty to do much of my killing for me, but just to keep the enemy's heads down and maybe erode their morale a little until my infantry gets close enough to do the job. Because you get a lot more shots with the 81mm, it is more useful for this kind of work.

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Um, suppression is also an effect of blast. So the same thing holds true. If you want suppression, bigger is better. Having more shells does help in the sense of more uniform coverage, though.

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I expect that you can also buy more smoke per buck with the smaller calibers too, though I have not tested this.

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Agreed. I would always want a 81mm module for an attack for this reason.

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BTW, it would have been interesting if you had been able to include the 105mm and 150mm in your test, as well as the artillery of other nationalities.

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The point was to demonstrate the effect. Testing other nations and calibers would add little. I agree it would be interesting, but so are things one can do with one's time other than running CM tests.

[JasonC]

I agree with Wreck that the big stuff is more effective for the price. Otherwise put, it is underpriced.

[Michael Emrys]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Wreck:

Um, suppression is also an effect of blast. So the same thing holds true. If you want suppression, bigger is better. Having more shells does help in the sense of more uniform coverage, though. <HR></BLOCKQUOTE>

Bigger is better as long as the shells land near to the troops you want to suppress. If you miss them, you might as well blow smoke rings at them. My observation so far (YMMV) is that a certain percentage of shots alway miss. The 81mm lands more shots per turn, therefore it is more likely to have at least one land near enough to do some good.

To put it another way, playing with bigger guns is rolling for higher stakes, but with an increased chance that you also might lose big. The smaller guns have a greatly reduced chance of giving you the big win, but they are more certain of getting you at least something.

Hope I made myself clear this time.

Michael

[Dschugaschwili]

A possible explanation of the "bigger is better" observation is the larger blast radius of the larger guns, meaning that you can hit more targets per shell. So if you have an arty round that has four times the blast value and 1.5 times the blast radius (about twice the area of effect) of another shell, you'd need only one eightth the number of shells to get the same killing effect on densely packed troops.

Dschugaschwili

[ParaBellum]

In a recent TCP/IP game one of my german platoons (regulars) came under heavy british arty fire (7.2").

Once the spotting rounds landed I quickly withdrew the platoon and the first salvo didn't cause any casualties. I kept moving my men and since the heavy arty fires much less shells and their reaction time is bigger than smaller I was able to survive the barrage with about 10 men lost.

The most important fact with heavy arty: You will cause heavy casulaties if you hit something.

As Michael already stated, it's always a kind of a gamble when using the heavy (and expensive) arty. I'd rather go for medium stuff with short readtion times and lots of ammo, like the 105mm or 120mm/4.2" mortars.

[Wreck]

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A possible explanation of the "bigger is better" observation is the larger blast radius of the larger guns, meaning that you can hit more targets per shell.

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Well, yes. But it is not about hitting more targets per shell, per se. The increased effectiveness would work even against a single target. The point is simply that you pay proportionate to total blast. But that effects are *not* proportionate to blast, but rather, blast^2. Probably. Certainly not linear in blast, though, which the prices are pretty much.

<BLOCKQUOTE>quote:</font><HR>

So if you have an arty round that has four times the blast value and 1.5 times the blast radius (about twice the area of effect) of another shell, you'd need only one eighth the number of shells to get the same killing effect on densely packed troops.

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I have the suspicion that blast value and blast radius are proportional, so that twice the blast value means twice the blast radius. Thus I don't think it would be possible to have a 4x blast value with only a 1.5x radius.

That is something worth testing, though.

As for dense packing, the arrangement and density of the targets has no effect on lethality. (That is assuming that all targets are in the beaten zone; adding troops outside clearly helps them survive.) Target density does affect variances in trials, though.