Artillery spacing question.

[BeWary]

Hi all.

Artillery seems to fall in a general circle around the spot you target. My question is: is this because of the distance to the target and/or inherent inaccuracy of artillery, or is it by design (meaning, artillery crews make slight adjustments before firing for the purpose of being slightly off-target and hitting a larger area)?

If it's by design, were there ever times when they called in an artillery strike with a small area to land in? I'm playing a scenario right now where there is really only one small area that needs to be shelled (the entrance to a bridge and the bridge itself), so a lot of my shots are being wasted.

Thanks.

BeWary

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"Liberty or Death?" Make it "Victory or Pretty Damned Badly Wounded", and I'm yours. - a prospective recruit during the American Revolution.

[M Hofbauer]

the impact pattern depenmds upon a number of factors, which means you can influence it.

the impact pattern will become more accurate/dense the higher the quality of your FO is (green - elite).

it is also much more accurate/denser if the FO has LOS to the target. be sure to unhide him else he's still inaccurate even though he's within LOS of the target.

for an intentionally widely dispersed impact pattern use the TARGET WIDE command.

hope this helps,

M.Hofbauer

[This message has been edited by M Hofbauer (edited 02-06-2001).]

[L.Tankersley]

CM artillery (except for rockets) actually falls in an elliptical pattern with the long axis oriented east-west. Arty batteries are assumed to be located east or west of the battle area (because of the general geometry of fighting in western Europe in '44-'45, with the Allies advancing from west to east). The ellipse results because range error tends to be greater than azimuth error when firing indirect fire (or direct fire for that matter). You can see the same sort of effect with onboard mortars: they tend to miss long or short more often (and by a greater distance) than they miss left-right. [Tactical tip: you can often figure out a rough position for an unspotted or unidentified enemy mortar team by looking at the craters and using them to determine a line of bearing.]

This was discussed at length in the past; search especially for posts by "Bullethead" who used to do this sort of thing for a living. He actually contributed a lot of feedback to make the arty model that made it into the final version of CM considerably more accurate, IIRC.

As far as shrinking the area in which the shells are landing, if the FO has line-of-sight to the target point I believe the shells will tend to land closer to the target. Firing on a TRP may or may not have a similar effect, I don't remember. Again, I think Bullethead posted a pretty comprehensive summary of artillery patterns somewhere.

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Leland J. Tankersley

[Pak40]

Originally posted by M Hofbauer:

the impact pattern will become more accurate/dense the higher the quality of your FO is (green - elite).

I don't think this is true. Several months ago I ran a test with several grades of 105mm FOs and I didn't find any correlation between accuacy and their experience. In fact the only difference was a shortened time to wait before the shells impacted.

Try the TRP for a tighter barrage. Also try onboard mortars that have a LOS to the target, these have a very tight barrage although they are lighter calliber.

[This message has been edited by Pak40 (edited 02-06-2001).]

[This message has been edited by Pak40 (edited 02-06-2001).]

[BeWary]

Thanks guys, I'll check out Bullethead's posts. I understand how artillery is more accurate with LOS in CM, however, I was more questioning reality than I was CM.

Was it possible during WW2 to have artillery fall in a tighter circle/ellipse than is possible even with LOS in CM? I'm just wondering if the accuracy in CM is "as good as it got" in real life with LOS.

I guess my other question was: Is it possible to land all of the shells on one spot, or do the artillery crews intentionally make adjustments to make the impact area larger.

I'll still try to find what Bullethead had to say. Maybe he answered these questions.

Thanks again,

BeWary

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"Liberty or Death?" Make it "Victory or Pretty Damned Badly Wounded", and I'm yours. - a prospective recruit during the American Revolution.

[Sgt Fred]

Originally posted by BeWary:

Hi all.

Artillery seems to fall in a general circle around the spot you target. My question is: is this because of the distance to the target and/or inherent inaccuracy of artillery, or is it by design (meaning, artillery crews make slight adjustments before firing for the purpose of being slightly off-target and hitting a larger area)?

If it's by design, were there ever times when they called in an artillery strike with a small area to land in? I'm playing a scenario right now where there is really only one small area that needs to be shelled (the entrance to a bridge and the bridge itself), so a lot of my shots are being wasted.

Thanks.

BeWary

The impact pattern that artillery falls in is called a sheaf. Although there are many different types of sheafs, three types are the most common; normal sheaf, open sheaf, and closed sheaf (also called converged or point sheaf). In a normal sheaf distance between impact points is approxmately twice that of the bursting radius (ie 155mm = 100m, 4.2" = 50m, etc.). In a closed sheaf all tubes are adjusted to impact the same point. In an open sheaf, tubes are adjusted so that the rounds from the battery fall over a larger area. Open sheafs are often used for smoke missions and supressive fires.

There's a detailed discription of artillery sheafs and such at the following URL:

http://www.jmkemp.demon.co.uk/artillery/sheafs.html

As far as CM goes, M. Hofbauer has addressed the issues of FO quality and LOS as well as the "target wide" (open sheaf) command nicely. I suppose there are some that would like to see more detailed control of arty in CM, but the game will become Artillery Mission if arty realism becomes a priority.

Later

[BeWary]

Thanks for your response Sgt. Fred. That answers my questions. Although, I don't see how adding a "Target Tight" command to CM would suddenly make it Artillery Mission. If it was used regularly, it should probably be modeled. I'm not asking for it in CM, but perhaps in CM2 if appropriate.

Now I'm wondering why TRP fire would fall in a tighter circle than normal artillery fire with LOS? It seems from Sgt. Fred's response that they can get more accurate if they want to in a normal firing mission, and I thought the point of a TRP was simply to decrease the time-to-target. So why would a TRP also make for a tighter sheaf? <- my new buzz word for the day

Or is a TRP the hidden "Target Tight" command? Just kidding...

BeWary

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"Liberty or Death?" Make it "Victory or Pretty Damned Badly Wounded", and I'm yours. - a prospective recruit during the American Revolution.

[Jeff Heidman]

I always wondered why lack of LOS would result in a looser spread of shells.

That seems unrealistic to me. The guns are going to fire at what they *think* is the correct spot regardless of whether or not they actually drop the rounds where the FO expects.

It would seem to me that when they miss, the entire battery would miss, hence the dispersion would be the same, but the center point would be moved.

Jeff Heidman

[Roborat]

Your idea is valid, up to a point. In real artillery, It is possible to have a fairly tight impact pattern, but it is impossible to get all the rounds to hit right beside each other. But don't forget, artillery is an area weapon, and the firing patterns are usually set appropriate to the target. The kill radius of a typical 105 HE charge is 30 metres, and a 155 is about 100 metres (I can't remember exactly, will have to check). There usually isn't any deliberate tweaking of the range and elevation settings to spread out the rounds, it's not needed, that will happen anyway, due to variations in atmospheric conditions and ammo charge, slight movements when the guns fire, among other variables. Even a slight difference in weight will have a big difference in impact location. When a typical line pattern is called, which is what CM models, sort of, the guns fire "open", withe the impact pattern generally resembling the deployment pattern of the firing guns. When a tighter pattern is required, (or something besides a simple east-west line, as in CM, which, by the way, I would really like to be able to vary, ie: do boxes, angled lines, circles, rolling barrages, etc.) the corrections are made to the targetting settings, both elevation and bearing, to get the guns to converge to a point. However there still will be considerable scatter. Real life tip for the infantry types: the safest place to be, if your caught out in the open in an arty barrage, is in an impact crater from the barrage, as the guns will NEVER put another round into the same hole (well, there is a statistically insignificant chance, so unless its an incredible number of guns in the barrage, it should work).

[Roborat]

Sorry heidman, your post wasn't up when I did mine, but your comment is right about the trps. All the trp would accomplish is a faster tot, as the calculations to hit that spot, and usually a spotting round or two, have already been done. A call to hit that point would result in a near instantaneous response, it would have no effect on the impact pattern at all.

And I like that artillery mission idea, I lik it a lot. It would make a great game, you could play the foo, single handedly destroying the nazi, or allied, hordes. I think BTS should do it.

[BeWary]

Ok, another question about the TRP. How would the batteries know they have pre-calculated the spot correctly without firing a few rounds at it? And if they fired a few at it, wouldn't it alert the incoming enemy when they see big craters right where they plan on going? If I saw that, I might think about taking a different route.

I'm just full of questions today. Or am I just plain full of it?

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"Liberty or Death?" Make it "Victory or Pretty Damned Badly Wounded", and I'm yours. - a prospective recruit during the American Revolution.

[Sgt Fred]

Originally posted by BeWary:

Thanks for your response Sgt. Fred. That answers my questions. Although, I don't see how adding a "Target Tight" command to CM would suddenly make it Artillery Mission. If it was used regularly, it should probably be modeled. I'm not asking for it in CM, but perhaps in CM2 if appropriate.

Now I'm wondering why TRP fire would fall in a tighter circle than normal artillery fire with LOS? It seems from Sgt. Fred's response that they can get more accurate if they want to in a normal firing mission, and I thought the point of a TRP was simply to decrease the time-to-target. So why would a TRP also make for a tighter sheaf? <- my new buzz word for the day

Or is a TRP the hidden "Target Tight" command? Just kidding...

BeWary

I don't know why a TRP mission should result in a tighter sheaf unless it is assumed that batteries fire a closed sheaf at registered points. It shouldn't make a difference in sheaf dimention, just time of response to a fire request.

[Guest Germanboy]

Originally posted by BeWary:

Ok, another question about the TRP. How would the batteries know they have pre-calculated the spot correctly without firing a few rounds at it? And if they fired a few at it, wouldn't it alert the incoming enemy when they see big craters right where they plan on going?

Good question - the answer is MT fuses. Airbursts.

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Andreas

Der Kessel

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

[BeWary]

Ahhhh, didn't think about that. Thanks Germanboy.

Though I'm assuming you meant VT instead of MT? After all, I don't think the Maryland Theatre would have had anything to do with testing artillery rounds in WW2.

** acronym definition provided by www.acronymfinder.com **

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"Liberty or Death?" Make it "Victory or Pretty Damned Badly Wounded", and I'm yours. - a prospective recruit during the American Revolution.

[This message has been edited by BeWary (edited 02-06-2001).]

[This message has been edited by BeWary (edited 02-06-2001).]

[This message has been edited by BeWary (edited 02-06-2001).]

[BeWary]

Double post, sorry.

[This message has been edited by BeWary (edited 02-06-2001).]

[Sgt Fred]

Originally posted by BeWary:

Ok, another question about the TRP. How would the batteries know they have pre-calculated the spot correctly without firing a few rounds at it? And if they fired a few at it, wouldn't it alert the incoming enemy when they see big craters right where they plan on going? If I saw that, I might think about taking a different route.

I'm just full of questions today. Or am I just plain full of it?

Assuming a battery has the time (ie prepared defense) firing a few rounds at a registration point is exactly what you do. As long at you don't use delayed fuses there is very little cratering or other evidence not to mention that if you're close enough to the RP to detect that evidence, you are probably about to have a very bad day. I would note here that BTS uses "Target Reference Points" in CM not registration points. Registration points are used in the defense for pre-planned fires and, along with ballistic meteorlogical data, to quantify some of the irregularities associated with indirect fire weapons. In the US Army we also used something called Fire Mission Reference Points which were nothing more than pre-plotted points that FOs could reference to save a little time. The fire directed at these points wasn't more or less accurate, just faster, and it still had to be adjusted by the FO.

[Guest Germanboy]

Originally posted by BeWary:

Ahhhh, didn't think about that. Thanks Germanboy.

Though I'm assuming you meant VT instead of MT?

MT - mechanical timed. The standard method of achieving airbursts (and regulating flight time of AA guns) until the development of VT in 1944. Used by all armies.

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Andreas

Der Kessel

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

[Radar]

Now I can't say what happens in the game, but artillery guns are set up in a staggered formation and possibly put into platoons to run consecutive fire missions. One gun per plt. is used for adjustment while the others follow along. Battery fire is accomplished the same way. Yes VT is nice But MT is just as sweet. As for jumping in a crater...if its that close, jump in and look around and see if you can see the sun shining and birds singing...don't worry! Your already in heaven!

Three rounds HE, fuse QT!

Now, I'm afraid that I don't go into many details, but here in the game Arty is modeled for playablity.

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Sometimes your the Big Dog, and sometimes your the Hydrant.

[Roborat]

No, they are not going to waste expensive MT/VT or any other fuses on setting up a TRP, they would use good old contact fused HE, it's the cheapest and most common fuse. Besides, with an airburst, how would the foo see well enough to adjust. Even when they are shooting VT they adjust with HE.

And yes, if you wander into an area and see a few fresh craters, without an obvious target, you might want to shift over a bit, really quickly.

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"With cat-like tread, Upon our prey we steal;

In silence dread, Our cautious way we feel." -G&S

[coralsaw]

Originally posted by Roborat:

Real life tip for the infantry types: the safest place to be, if your caught out in the open in an arty barrage, is in an impact crater from the barrage, as the guns will NEVER put another round into the same hole (well, there is a statistically insignificant chance, so unless its an incredible number of guns in the barrage, it should work).

Roborat

I am not pretending to know how it works in RL, and your tip has value, as it is probably safer to be in a crater than in the open, but I don't think that your remark holds true in theory. The system has no memory, so assuming the crater is not the effect of a spotting round (in which case the gun gets recalibrated), the chances of a shell falling anywhere in the designated area should be the same.

It's like saying that a person who's won the lottery won't win it again. Well, it's probably true, but in theory completely wrong.

Regards

[Guest Germanboy]

Originally posted by Roborat:

No, they are not going to waste expensive MT/VT or any other fuses on setting up a TRP, they would use good old contact fused HE, it's the cheapest and most common fuse. Besides, with an airburst, how would the foo see well enough to adjust. Even when they are shooting VT they adjust with HE.

While I don't have the info for TRP - using MT for spotting rounds was normal practice for German CB FOOs (my grandfather was one), and using MT for ranging is again suggested procedure for direct-fire with heavy AAA (88s). I just assumed it would work the same with TRP, but am happy to be corrected.

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Andreas

Der Kessel

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

[jasoncawley@ameritech.net]

No, they will not all hit the same point. Most artillery mission in real life would be more like the "wide" pattern in CM - the "standard" CM mission is already "tight" by real world standards. Most missions are fired at targets that are not nearly as close to friendly forces as typical distances in CM - e.g. in prep bombardments, harassment fires, etc. They are not "missing" "on purpose" in that last ~100 yards of scatter. That is just how straight they can point, in practice, from 5 miles away at something they can't see.

Incidentally, CM gives far too high accuracy for on-map mortars, apparently because it uses the same direct-fire targeting routine as flat trajectory, high velocity, rifled cannons fired from heavy, stable platforms and added by powerful optical sights. The "uber-mortar" effect this can create is somewhat laughable. They might be better advised to use their excellent artillery fire routine for on-map mortars, with an adjusted CEP (circle of probable error).

I can explain why this is so. Mortars are smoothbore weapons, not rifled. The round is somewhat stablized in flight by a set of tail-vanes, like on a dumb bomb. Anyone who has played with those knows they still wobble, with a pendulum like motion in one direction and a slow precession or spin in another, both perpendicular to the path of flight.

Also, there is significant "windage" in mortars, unlike rifled cannon. Windage is the difference between bore diameter and round diameter, and it let's gases from the explosion that sends the round flying, "vent" in uneven and different ways from shot to shot. Mortars require it, because the round is just dropped down the barrel, and without some windage it would just plain get stuck.

The sights on mortars are comparatively primitive, and moreover the kick from each shot tends to burrow the base-plate a little deeper into the soil, "bumping" the actual firing angle from shot to shot, even with careful recalibration. Wind is also causing the rounds to drift during their long "hang time".

What all of that adds up to is a scatter-graph landing of shots regardless of how well you aim the mortar. It is not at all just a matter of having the wrong range. The rounds just do not come down at the same location in each shot, even if the mortar was pointed in exactly the same direction, which it incidentally isn't.

The CEPs of light mortars are in the 10-20 yard range, meaning only half the rounds can be expected to fall that close to where the mortar is exactly pointed, ignoring errors in range estimate. This does not much matter against enemy infantry, as the whole point is to fire many rounds in rapid succession and produce fragmentation effects over an area twice that size or more. But mortars are not nearly as useful against point-targets like guns, vehicles, or individual MGs and teams, as CM pretends they are.

Incidentally, this is definitely one thing I would like to see change in CM2 or a patch. I suggest that the excellent off-board artillery "random fall of shot" model is a much better representation for mortars, even if fired from on the map. If should not be too hard to use that routine, since it already exists. You would just need to adjust the scale of the scatter lower, to more like 2/3rds within 30 yards for a single on-map mortar, instead of 2/3rds within 100 yards. (If the angle of the ellipse for the fall of shot could be made the firing angle, that would be even better).

In other words, mortars do miss from side to side in real life, by plenty, because much of the "miss" is from the random elements of their flight path, not from ranging error.

[Pak40]

Jason,

thanks for the info, pretty interesting stuff. I hope BTS sees your post. How did you learn all of this, were/are you in the military?

[tss]

I have been hit by a severe case of Real World lately, so I hadn't noticed this thread earlier.

Roborat wrote:

Real life tip for the infantry types: the safest place to be, if your caught out in the open in an arty barrage, is in an impact crater from the barrage, as the guns will NEVER put another round into the same hole

One Finnish veteran of the Winter War wrote in his memoirs [i can't remember exactly who, but he fought at Summa] that during the Soviet preparatory barrage before the February major offensive one of his pals followed that advice and jumped into a fresh shellhole. However, about 30 seconds later a new shell (152 mm) landed in the same hole, and only thing that they could later found was a boot.

Of course, the Red Army had pretty ridiculous number of guns firing in the area.

- Tommi

[coralsaw]

IIRC, Guy Sajer in The Forgotten Soldier has a similar description.

Like you said, gazillions of guns...