Is it just me or are 81mm mortars (off-map) really good value?

[Ales Dvorak]

But, hey!

Max range is 6 km (hmmm ... miles, yes I know, recalculated!) with add. (powder )

[-Havermeyer-]

200 rounds of smoke (or 180 with the kraut). You can push entire companies into the enemies backfield.

I love the little mortar for smoke. But the big rounds for killing.

[Guest JAZZA]

Originally posted by KiwiJoe:

Goanna... what the hell are you talking about?

I'm about done proving myself, but if you think your skilled enough to give me a slight challenge I may be some what interested.

Lol! What's your win/loss record now?

[jasoncawley@ameritech.net]

The problem with Kiwi Joe's calculation, is that he assumes the effect of number of rounds and the effects of blast are both the same, linear. But they aren't. Blast declines with the distance from the impact point. A few big'uns do have higher "peaks" in total blast delivered, but they deliver less on the average part of the "blanketed" area, compared to more numerous smaller impacts.

A better measure of the *expected* delivered firepower on troops under a barrage is blast^.5 times number of shells. Artillery modules are much closer to one another in these terms, varying by about a factor of two at most. If you look at this total mean firepower measure, and divide by the point costs, the light mortars are indeed delivering more average firepower per invested point, but because the module is cheaper, not because it is more powerful.

The medium artillery types - 105mm artillery and 120mm mortars e.g. - come out as "bargains" that are about half the same average bang per point spent as the 81s, but of course with their sharper firepower peaks. By the time you move up to 150mm or 155mm, you are down to more like 30% of the mean fp to beaten-area, per point spent. You are "paying for variance" in that case - the chance of a few close shells doing far more damage.

Another issue here is troop qualities. The morale effect of delivered firepower varies with the target's quality level, and the rate of the delivered firepower, not just the total amount. Greens will be broken by firepower that does not kill large numbers of men in a short space of time, especially if that fire is continued for any length of time. Regulars are a bit more resistent, but e.g. in woods but not in foxholes, they are easily broken by a minute and a half of 81mm mortar fire. Vets in foxholes are another story, and will ride out such relatively light shelling in much better shape, and recover more rapidly and totally. Even they do not like it very much, obviously, and will hardly be at their best just after a 2 minute 81mm barrage lifts.

What is true in Kiwi Joe's point, is that the limited number of shells in the other artillery types, does not mean they don't have much firepower over the whole time of the module's firing. They do. And they deliver it in "higher dosages" per unit time, which matters against higher quality troops in particular.

I consider a single module of light mortars standard, effectively part of an infantry force purchase and hardly "supporting artillery" at all. But after the first of those, I will buy heavier stuff. I prefer the 105mm from the Americans (arguably the single best all around module in the game, but fully priced in point terms), and the 120mm mortars or 105mms as the Germans. Realistic too.

[KiwiJoe]

Didn't I beat you a month or 2 ago Jazza? Your name is on my kill list. I think I remember you being a reasonable challenge

23-2 is my record. 1 lose was my 1st game eva (to jarmo), the other was on defense back when the attacker got a million extra points

Obviously I'm not done proving myself as I'm still making excuses for my losses

[Nabla]

Originally posted by Goanna:

Nabla - I have to disagree with you in the exact situation you describe, but for a very different reason. In this situation (attacking infantry in foxholes), I find it best to get my infantry as close as possible first, then laying in the smoke just before I close with the enemy. If you are using explosive shells in this situation, you are basically wasting them, but getting my infantry 'up close and personal' with an opponent through the concealment that smoke provides make the 81 mm FO extremely valuable

An excellent point. In my case there were circumstances which made smoke also pretty useless (night battle in fog, and the enemy had SMG squads, so I did not want to get close and personal with them ), but generally your strategy would make a lot of sense. Thanks for the tip.

[This message has been edited by Nabla (edited 02-14-2001).]

[KiwiJoe]

Jason: 1 factor you don't pick up on is tree bursts. I find these do the most damage overall to infantry and AT guns, which of course, are often placed in woods, pines or scattered trees. I'm not 100% sure on the caculation but I remember reading that a tree burst basically doubles the blast of the round. Thus a 81mm round with a blast of 19 tree bursts at around 40, where as a 155mm tree-burts at around 400! You don't have to land a shell very close at all to kill with a 400 blast. Now you could argue that with more rounds the 81mm spotter will get more tree bursts which will make up for this. But there is no way he'll get 10x more of them.

[Pacestick]

Originally posted by KiwiJoe:

Didn't I beat you a month or 2 ago Jazza? Your name is on my kill list. I think I remember you being a reasonable challenge

23-2 is my record. 1 lose was my 1st game eva (to jarmo), the other was on defense back when the attacker got a million extra points

Obviously I'm not done proving myself as I'm still making excuses for my losses

I do not rememebr getting a million extra points but only the extra the program gives to the attacker. What are you talking about

[Guest Germanboy]

Originally posted by Pillar:

So in essence the 81mm is still a wonderful AT weapon nullifyer. If you want to kill guns at a distance that have significant fields of fire affecting the objective AND the approach (and this isn't a common situation unless you are in very open terrain), than the 120mm will do.

- Pillar

Jasper is right Pillar. Misunderstanding on my part - I thought of the Commonwealth 3" AT mortar of late fame, not of the use of mortars to suppress guns/HMGs. You are totally right, they are great in that role.

------------------

Andreas

Der Kessel

Home of „Die Sturmgruppe“; Scenario Design Group for Combat Mission.

[Gremlin]

KiwiJoe, I still find that 81mm mortar tree bursts are enough to cause substantial casualties, regardless of other factors. A close tree burst from 81mm can often take out 1/3 to 1/2 a squad, it seems. As I think Jason mentioned, the morale benefits from the constantly falling shells, coupled with tree bursts, can really mess up infantry in a hurry, unless they're very experienced.

------------------

New to Combat Mission?

Visit CM Boot Camp at Combat Missions for tips.

"90% of the crucial decisions in this business are made by idiots who don't even play games." Cliff Bleszinski

[jasoncawley@ameritech.net]

The reason for the square root on the blast part of the calculation, is that blast falls off with distance from the target. For guns other than rockets (or purposefully "wide" targeting), the size of the scatter patterns are about the same in CM. The rest is just math.

Basically, you can expect 2/3rds of the shells fired to fall within 100 yards of the aim point. Ignoring the rest, those 2/3rds will thus be in an area of around 31460 square yards. If there were 35 fired, 23 are in that area, or 1464 square yards per shell in that area. So the mean distance to the nearest boom will be around 38 yards. Fire 200 rounds and 133 will land inside, or 236 square yards per shell in the zone. So the mean distance is only around 15 yards.

Well, how much more effective is a round at 15 yards, compared to a round at 38 yards, for the same blast? The blast goes out in a wave like the surface of a sphere. At 2.53 times the distance, the total surface area of that sphere is 6.42 times as large. 198 blast at 38 yards will thus be about like 31 blast at 15 yards.

31 blast is higher than 19 blast. The 35 rounds of 155mm therefore deliver more average punch. But the module (American case) costs 204 points. It is therefore delivering a mean blast of 0.151 per point spent, on the "beaten" area. The mortars are delivering less. But the module only costs 99 points. It is delivering 0.192 per point spent, which is about 5/4ths as much.

None of which contradicts the point, that the 155mm is delivering more mean blast. It is. It just costs more to reflect that, and enough more to cover that part of the difference. What you are left getting in return of that slight down-tick in mean blast over the beaten area, is much sharper peaks in the hardest-hit regions. And sharper peaks will tend to mean higher immediate casualties, as opposed to the average morale effects of mean delivered blast.

Look at the area that lies within 2 meters of an exploding 81mm shell, firing that whole module. 133 shells landed "in zone". The total area that close to one or another mortar shell, is 1671 square meters. That is 5.3% of the total beaten area. Now, take the 19 blast figure as the figure for 10 meters away. Then at only 1/5th the distance, the "distance adjusted blast" is going to be around 25 times as high, or 475. You can explain the peaks of the mortar distribution, then, as 5.3% of the zone hit with 475 or higher blast. Notice, you practically need a direct hit (well less than the size of a foxhole) to get this effect with the mortar. 2 yards is as close as "close" gets in CM terms; the firepower *peaks*. Everything a near-hit can add to a 81mm round has already been added.

Move to the parallel calculation with the 155mm. We want to know what area will be covered by 475 or higher blast. Since the original blast is 198, we only need 2.4 times from being under 10 meters distance. That means being 6.5 meters away is close enough. 23 shells landed in the beaten zone, so the total area can be calculated as 3012 square meters. Which is 9.6% of the beaten zone, more but not quite twice what the mortars got (1.806 times). Again, the 155mm module hits harder, but the harder is fully reflected in the module cost (2.06 times the points for Americans).

I realize this sort of analysis may seem completely obscure. But if you follow it, the geometry of the relationships may appear to you, and you will be able to get a good intuition of the different effects of many-little vs. few-big detonations, which is related to why one suppresses and the other causes casualties, etc.

You have to picture a "field" (in the physics sense) over the beaten area, a sort of height map or set of contour lines. To each point a blast value is assigned. The largest contributor of blast at any given point (usually overwhelmingly so) is the nearest round. Each round is a "peak" on this "map". The peaks fall off as inverse square (why? The surface of an expanding spherical blast-wave, area 4 pi radius ^2). The locations of the peaks throughout the beaten area are random. The number of peaks is ~2/3rds the number of shells. The height of the peaks is determined by the blast rating of the shell.

I hope this makes sense to at least some.

What is right about Kiwi-Joe's statements and reflects his experience, is that the big modules do hit harder, despite the small number of shells they fire. And they have larger peaks, which especially can effect dug in or higher quality troops, and kill rather than break.

But what is missing from his previous analysis, is #1 that more shells partially raises the blast effect of the smaller rounds, not just because more land, but because the nearest one lands *closer*.

This is *not* enough to reverse the difference between a module of 81mm and a module of 155mm - the 155mm hits harder, despite the closer hits from the 81mm. But it *is* enough to put the difference close to #2, a second factor, the difference in the *prices* of the two types, at the unit-selection stage.

The 155 *is* providing more bang, but not as much more bang as a simple "shells times firepower rating" look suggests. And the 155 costs more to get that bang. The bang-per-buck of the different types is close. It is slightly higher for the mortars. The 155, in return, is more likely to effect the hardest target types (high quality and dug in), because its peak fp values, in a small portion of the "beaten zone", are higher (e.g. places within 4m of a 155 impact, say).

I hope one "pass" or another is somewhat clearer than mud...

[jasoncawley@ameritech.net]

I can try in another way altogether, leaving out the full geometry of it and putting it in simpler terms.

Some people buy 81mm mortar modules with 150-200 rounds, for 70-100 points. They then use them to fire 3-4 missions. This means they are expending around 25 points worth of artillery ammo on a typical fire mission target.

If instead you spend 200 points on 35 155mm, you might well fire them all at a single target, or at most two. You are thus firing 4-8 times as much "investment" at the target, per fire mission, as the "dink 'em with 81s" person above.

And you will get at least reasonable "value for money" on the spending side. Well within a factor of two overall. So darn tootin you are going to hit each target several times harder. You spent more. You probably fired it at fewer targets. You darn well better do more to each.

[This message has been edited by jasoncawley@ameritech.net (edited 02-14-2001).]

[KiwiJoe]

Nah I never fire off more than 8 rounds at a single target... that is usually enough to rip a platoon. Thus I get around 4 fire missions with 1584 blast in a turn (8 x 198). 81mm delivers around 50 shells per turn thus: 50 x 19 = 950 blast in a turn for 4 fire missions. I find 2/3 - 3/4 of that blast is wasted simply becuase the shells have to land almost on top of a squad, or get a tree burst to kill. The only shots wasted with 155mm are the 1's that stray well off course, anything that lands anywhere near the intended target WILL cause kills, and panic.

You are correct with the costings though... 155mm is more expensive per blast point delivered:

German 81mm: 19 blast x 150 shells = 2850 total blast / 71 = 40.1 blast per point.

Yanky 155mm: 198 blast x 35 shells = 6930 total blast / 208 = 33.3 blast per point.

However as I said above I find most of the 81mm shells are ineffective because low blast means only the shells landing on, or right next to, infantry cause kills. Whats my point? 81mm doesn't kill, it mearly pins. 155mm kills and pins and panics and routs Its worth the extra cash. The only thing is you can't "spectulate" with your shots. You have to positivly I.D. the enemy before letting lose with any of those 35 shells.

[Guest Big Time Software]

Hehe... this thread reminds me of several others where X unit/weapon is held up as the Swiss Army knife of the game.

While I agree with KiwiJoe that artillery is superior for killing the enemy, round for round (which is very realistic), I do not agree that artillery is the best all around weapon for any and all situations.

Mortars, in combination with other weapons or good luck, can wreck an enemy force just as effectively as artillery. In some ways more effectively. Fire "Wide" with an 81mm off map FO, or better yet with two of them (the cost of 1x105 FOs = 2x81mm FOs). You can screw up two companies worth of advancing infantry, even if correctly spaced apart, without any problem. Try that with a single 155 or 105 FO. You might hit one platoon REALLY hard, but the rest will slip through. And in woods, treebursts from 81s are death even more than the big stuff simply because there are MORE chances over a LARGER area to inflict casualties.

That being said, mortars have their limitations. Attacking entrenched troops is one. Artillery is what you need for that, if your intention is killing them.

And there is the key... the person that uses mortars, of any size, as if they are artillery will get disapointing results. But those who use it as intended, as an interdiction weapon or combined with other wapons, will find mortars to be very effective. In fact, we have had this same discussion before about the US 60mm mortars. Some say they are useless, others swear by them. Just like the WWII vets BTW

I guess my point is that if you use mortars the way they were designed to be used, they are deadly. If you use artillery the way it was designed to be used, it is also deadly. But neither can do everything that the other does just as effectively. And that my friends is why the armies of the world still have mortars AND artillery in their service

Steve

[Guest JAZZA]

Hehe..yeah Kiwijoe,you beat me about 4 months ago I believe in the pbem nz'ers challenge.

Regarding 155mm arty,I find if you time it right you can get 6 fire missions from it.

5 volleys of 6 rounds a piece(4 rounds + 2 spotting)and one 5 round volley(3 rounds + 2 spotting).One volley can be lethal to tanks or troops,especially with tree bursts.

[Sirocco]

Originally posted by Big Time Software:

Fire "Wide" with an 81mm off map FO, or better yet with two of them (the cost of 1x105 FOs = 2x81mm FOs). You can screw up two companies worth of advancing infantry, even if correctly spaced apart, without any problem. Try that with a single 155 or 105 FO.

I think you also have to bear in mind the size of the battle. I would normally take an 81mm FO and a 75mm FO with three or four TRP's on an 800 point defend game. With limited points the alternative is a single 105 or heavier FO, and if you can get good treeburts from your lighter FO's I think it's the better choice, but then I'm still learning.

------------------

"He belongs to a race which has coloured the map red, and all he wants are the green fields of England..."

- Joe Illingworth, Yorkshire Post War Correspondent

[Scipio]

The IMO most useless artillery units are the german rockets. I count usually less then 20% of hits in the closer target area. And if fired 'blind', they kill more of my own men then enemies.

------------------

Keine Gefangenen!

Visit my Combat Mission Sound Mods site!

Scipiobase

Join the Blitzkrieg Wargaming Club

[Guest JAZZA]

Scipio,rockets do have a use in the right situation .Check out this thread: http://www.battlefront.com/discuss/Forum7/HTML/000491.html

[Olle Petersson]

After checking out some German TO&Es for 44-45, it seems like having 81mm off map mortars is unhistorical in many cases!

If you get a German Infanterie or PzGrenadier company you'll get two on map mortars (on legs or halftrack). These are a part of the battalion 81mm mortar battery, and the typical type of deployment.

Battalion artillery is one 12cm mortar battery, so having a spotter for this is allright.

Cheers

Olle

[Cybeq]

Use mortars to fix the enemy in place and the heavy stuff to kill them off. Mortars respond quicker so you can react to enemy movements. When they're pinned bring on the 105-155mm. In QB's I'll buy the heavy stuff first and if I have enough left over then maybe some mortars. If you know where the enemy is at you don't have to pin them first. Also, I'd rather have on-board mortars than FO's.

------------------

"To subdue the enemy without fighting is the supreme excellence." -Sun Tzu, The Art Of War

[Sirocco]

Originally posted by Cybeq:

I'd rather have on-board mortars than FO's.

The problem with on-map 81mm mortars is they have to see the target, or have a HQ spot for them, and when they fire that puff of smoke does give their position away.

Perhaps 81mm FO's don't have the hitting power to annihilate, but they can reduce the effectiveness of an attack through the careful use of treebursts, to the extent the defenders are in a much more favourable position.

The bottom line is how many points you have to spend, and making best use of what you can afford.

------------------

"He belongs to a race which has coloured the map red, and all he wants are the green fields of England..."

- Joe Illingworth, Yorkshire Post War Correspondent

[Ales Dvorak]

Steve,

Welcome to Ljubljana again!

[Gunny Bunny]

Originally posted by Nathman:

81mm FO's are a great value IMO. To keep them from running through their ammo too quickly, I usually re-target them slightly over consecutive turns so there is about a 10-15 second delay before they start firing again.

Not sure what this means !

When I re-target my 81mm there is a 1 or 2 minute delay not a 10-15 second delay.

1 to 2 minutes at arty time can be as much as double the regular clock !

Regards,

GB

[Guest Michael emrys]

Originally posted by Gunny Bunny:

Not sure what this means !

When I re-target my 81mm there is a 1 or 2 minute delay not a 10-15 second delay.

1 to 2 minutes at arty time can be as much as double the regular clock !

You are obviously retargeting into an area to which your FO has no LOS. That's why the big delay.

Michael

[Nathman]

Actually, I'm not sure if retargeting to a place where the FO has no LOS makes any difference. I believe it is dependent on the distance from the original target to where it is re-targeted. If you re-target within a certain radius from the original, the delay is only usually 10-15 seconds (denoted by a green line if in LOS), but if you stray outside that radius, the delay will be 1-2 minutes (denoted by a blue line if in LOS). If not in LOS, then I don't believe it is possible to know where the delay will jump up to 1-2 minutes - you just have to take a best guess.