Artillery shell dispersal query part two

[noob]

I posted a question earlier this week about whether range affects the dispersal of artillery shells and i was given a link to this site: http://nigelef.tripod.com/errorsmistakes.htm

I was also advised that as a house rule that an area fire circle should be no larger than 70m radius.

According to the article range is not a significant factor, however after reading the data for a single 25 pdr gun firing from 8000 yds, the shell dispersal is stated as an ellipse measuring 30 x 4 yds, which would mean a 4 gun battery with a 10 yard space between guns could only cover an area of 30 x 34 yds, which seems very small considering the area targeting circle in CMBN can be as big as 400m.....have i read the article wrong ?

[akd]

I posted a question earlier this week about whether range affects the dispersal of artillery shells and i was given a link to this site: http://nigelef.tripod.com/errorsmistakes.htm

I was also advised that as a house rule that an area fire circle should be no larger than 70m radius.

According to the article range is not a significant factor, however after reading the data for a single 25 pdr gun firing from 8000 yds, the shell dispersal is stated as an ellipse measuring 30 x 4 yds, which would mean a 4 gun battery with a 10 yard space between guns could only cover an area of 30 x 34 yds, which seems very small considering the area targeting circle in CMBN can be as big as 400m.....have i read the article wrong ?

For 25 pdrs, 4 guns = 1 troop; 2 troops = 1 battery.

I think typical spacing for guns was 20-30 yards and frontage for a troop was something like 100-140 yards, but remember that coverage also includes the burst radius of the shell, not just the gun spacing.

The area target tool randomly spreads aiming points within the designated area, but dispersion and burst radius can extend the coverage beyond the limits of the circle.

[noob]

For 25 pdrs, 4 guns = 1 troop; 2 troops = 1 battery.

I think typical spacing for guns was 20-30 yards and frontage for a troop was something like 100-140 yards, but remember that coverage also includes the burst radius of the shell, not just the gun spacing.

The area target tool randomly spreads aiming points within the designated area, but dispersion and burst radius can extend the coverage beyond the limits of the circle.

Thanks for replying, for the sake of simplicity i'm going to go with the BF default artillery restrictions for my operation.

[JasonC]

I think the persistent confusion over this issue reflects a failure to distinguish the theoretical dispersion from each *gun* from shot to shot, with the practical dispersion in *called fire* from a battery.

The second is much larger than the first, because it involves the whole process of adjusting fire based on the small noisy sample of the first spotting rounds, the observors quite limited ability to gauge the scale of the miss to a distant target, and the like.

In practice, observors adjusted fire down to the nearest 50 meters and fired for effect. Attempts to correct within that scale would fail, because the observor would be chasing random variations. It is one of the oldest results in operations research that pushing corrections too far results in a wider, not a narrow, total dispersion of fire.

Technically the feedback of continual adjustments generates a system formally and mathematically equivalent to a driven oscillator, in which larger than normal random errors around the intended aim point reinforce themselves by generating bad called adjusts. The right place to cease adjustments is well beyond the theoretical standard error of the next shot from the gun's ballistics alone. It is more like the 90% confidence interval of the combined gun-variation and range-estimating observor error.

When there is infinite time to shoot and shoot again and minutely examine the fall of shot from round to round, as when creating a registration point during a long lull without action, rifled guns could be adjusted down to the the 25 meter scale. When time to FFE is a factor and the target will go to ground or move, the scale at which adjustments must cease and fire for effect be called is much larger. Actually gunnery practice reflected this, and aimed with wider, not converging sheafs, at target areas that were roughly 200 meter diameter circles, and stopped trying to adjust fire once spotting rounds were within 50 meters of the intended aim point.

Then firing more rounds, the spread of the guns themselves in the battery position as all fired on the same heading, and the shot to shot variation in coming from the shells themselves and gun ballistics, were relied on to indundate that large beaten zone with shell fragments.

In shorthand, practical gunnery was bludgeoning work, not scalpel work. The best target size was an enemy battalion position; even an enemy company area was on the low side (meaning some firepower would be wasted beyond its deployed area). The way CM players try to use battery fire with multiple adjusts to hit individual machinegun nests or to chase moving squads, just was not remotely possible in the real deal.

[JonS]

Campaign artillery rules, from noobs website:

Artillery

The Axis will always get one TRP per battery per CM battle.

The Allies will get TRP's if the campaign unit has a LOS on the target hex for two campaign turns (4 hours) without moving, fighting or firing.

In the campaign I am running both sides are not allowed to use the set up turn to plot artillery, even with a TRP, this is to ensure that the attacker has at least 5 turns to evacuate their restricted set up zones, and to ensure areas of the map that are outside the LOS of any spotters cannot be targeted without a TRP.

Point targeting and Linear targeting are also prohibited, and the minimum diameter for Area fire is 140m.

Any battery that is used during an campaign defensive or offensive fire phase cannot support a CM battle during the assault phase.

There are two assault phases per campaign turn, therefore any battery that is used in a CM battle during one assault phase cannot be used in the second for that campaign turn.

I'm not really sure why you distinguish between Axis and Allied, rather than attacker and defender.

Banning setup phase artillery seems unnecessarily restrictive, and used as a way of masking flaws elsewhere in your system, rahter than an attempt to encourage realistic use of artillery.

Minimum diamter of 140m is good, but I think it sould be fixed diameter of 140m (i.e., min and max is 140m). Although that might be unneccessarily restrictive. I can easily imagine a situation where you can get an area target of 130m or 150m, but not exactly 140m. You might want to introduce some flexibility along the lines of:

"Players are expected to use all guns in a fire unit (be it 1, 2, 4, 6, or 8 guns), and to use area targets with a diameter of 35m x the number of guns (that is; 35m for 1 gun or mortar, 70m for 2 guns or mortars, 140m for 4 guns or mortars, etc {and some special rule for rocket artillery}). If a player is unable to exactly set the expected diamter they may increase or decrease the expected diameter by up to 10% (with increased diameter being the preference). If the player still cannot set the area target, they cannot fire a mission at that location and must select a different aim point. Players must select 'General' as the fuze type (that is; no 'Personnel' airbursts). The player can chose whatever rate and duration for the mission they wish. Smoke missions are under the same rules."

That's a lot wordier than yours, but clearly sets out what the player is expected to do, and what they're allowed to vary.

[noob]

I'm not really sure why you distinguish between Axis and Allied, rather than attacker and defender.

Because in a previous post on BF about TRP's i was informed that given the fact that the Axis had occupied the area for three years they would have had plenty of time to create TRP's, whereas the Allies would have to do them from scratch.

Banning setup phase artillery seems unnecessarily restrictive, and used as a way of masking flaws elsewhere in your system, rahter than an attempt to encourage realistic use of artillery.

I had to introduce it because players were targeting artillery using aim points on terrain they had no LOS to, and as the FO does not need a LOS to the aim points during the set up turn banning set up turn targeting was the simplest way to guarantee this did not happen without TRP's.

Minimum diamter of 140m is good, but I think it sould be fixed diameter of 140m (i.e., min and max is 140m). Although that might be unneccessarily restrictive. I can easily imagine a situation where you can get an area target of 130m or 150m, but not exactly 140m. You might want to introduce some flexibility along the lines of:

As CMBN has batteries of 4 guns minimum, i divide all the PzC batteries into 4 gun units so the 140m restriction applies, i like the idea of the restriction being fixed so i will implement that given that was the reality of the situation, and i will adopt the General only rule for the choice of rounds.

Thanks for the information.

[JonS]

Because in a previous post on BF about TRP's i was informed that given the fact that the Axis had occupied the area for three years they would have had plenty of time to create TRP's, whereas the Allies would have to do them from scratch.

That's an odd thing to say. Creating a TRP - in the Real World - takes about 30 mins, tops, and you'd need to update the information every day or so anyway. The Germans would have better terrain familiarity throughout the region, but once you got past the coastal crust the numbers of TRPs on either side would be about the same.

I had to introduce it because players were targeting artillery using aim points on terrain they had no LOS to, and as the FO does not need a LOS to the aim points during the set up turn banning set up turn targeting was the simplest way to guarantee this did not happen without TRP's.

Oh, well, ok. It seems to me that targeting outside LOS (and away from TRPs) is a quite reasonable abstraction. But perhaps your set-up zones are too predictable.

As CMBN has batteries of 4 guns minimum, i divide all the PzC batteries into 4 gun units so the 140m restriction applies, i like the idea of the restriction being fixed so i will implement that given that was the reality of the situation, and i will adopt the General only rule for the choice of rounds.

I just had a look at the British guns in CMBN CW - they have fire units of 2, 4, and 8 guns or mortars. I'm pretty sure the US has at least one with 6 guns, and the Germans have at least one with 3. If you include on-map stuff firing indirectly under the same rules, players could be using a fire unit with 1, 2, 3, 4, 6, or 8 weapons.

Edit: for on-map weapons firing indirectly I'd suggest restricting them to 'Point Target.' That is, they should not be trying to be funky and distribute their rounds within an area or along a line by adjusting the bearing and elevation between rounds.

Thanks for the information.

You're most welcome Best of luck with your campaign.

[noob]

That's an odd thing to say. Creating a TRP - in the Real World - takes about 30 mins, tops, and you'd need to update the information every day or so anyway. The Germans would have better terrain familiarity throughout the region, but once you got past the coastal crust the numbers of TRPs on either side would be about the same.

What you have said about TRP's has led me to ban them altogether, it would just complicate things by having to have more rules to determine who has them and how many, if both sides don't have them then the playing field is level.

Oh, well, ok. It seems to me that targeting outside LOS (and away from TRPs) is a quite reasonable abstraction. But perhaps your set-up zones are too predictable.

They are too predictable

I just had a look at the British guns in CMBN CW - they have fire units of 2, 4, and 8 guns or mortars. I'm pretty sure the US has at least one with 6 guns, and the Germans have at least one with 3. If you include on-map stuff firing indirectly under the same rules, players could be using a fire unit with 1, 2, 3, 4, 6, or 8 weapons.

I will adopt the 35m per gun area target circle rule with the plus/minus 10% rule as well.

Edit: for on-map weapons firing indirectly I'd suggest restricting them to 'Point Target.' That is, they should not be trying to be funky and distribute their rounds within an area or along a line by adjusting the bearing and elevation between rounds.

I will adopt this rule.

Thanks again for the input

[JasonC]

On banning TRPs, it seems fine to me because CMx2 artillery is god-like enough without them. Overall the proposed rules sound reasonable enough.

On greater German terrain familiarity, actually they planned most of the defense right on the beaches and precious little inland. Also the men spent so much time building obstacles their training was shortchanged, to say nothing of any inland fire prep. They certainly were not registering guns anywhere inland before the invasion.

The allies, on the other hand, had absolute command of the air and L-5 spotter planes up within an hour of dawn all along the front.

I think the edge in artillery plotting very definitely has to go to the allies, therefore. Doesn't have to be a large one, but the Germans would not be better off in that department.

FWIW...

[noob]

On banning TRPs, it seems fine to me because CMx2 artillery is god-like enough without them. Overall the proposed rules sound reasonable enough.

Reasonable enough is good for me

On greater German terrain familiarity, actually they planned most of the defense right on the beaches and precious little inland. Also the men spent so much time building obstacles their training was shortchanged, to say nothing of any inland fire prep. They certainly were not registering guns anywhere inland before the invasion.

The allies, on the other hand, had absolute command of the air and L-5 spotter planes up within an hour of dawn all along the front.

I think the edge in artillery plotting very definitely has to go to the allies, therefore. Doesn't have to be a large one, but the Germans would not be better off in that department.

That makes sense, if i give an advantage it will be to the Allies.

Thanks for the input.

[winkelried]

On greater German terrain familiarity, actually they planned most of the defense right on the beaches and precious little inland. Also the men spent so much time building obstacles their training was shortchanged, to say nothing of any inland fire prep. They certainly were not registering guns anywhere inland before the invasion.

I would even add, that the terrain familiarity holds just for the units already in place before the invasion began. All units which were poured in as reinforcements after 6 June either had very limited beforehand knowledge of the area or none at all.