MGs fire trajectory-grazing fire affecting multiple units

[Michael Emrys]

Originally posted by Michael Dorosh:

</font><blockquote>quote:</font><hr />Originally posted by Michael Emrys:

</font><blockquote>quote:</font><hr />Originally posted by Lord Peter:

Modeling grazing fire will also affect how your own troops attack, as at many ranges your MGs will have to be careful when engaging enemy troops if your own units are between the MG and the enemy objective.

Which might be one big reason why the Vickers squads liked to use plunging fire. I am inclined to think that grazing fire was more of a defensive tactic, designed as I said earlier, to interdict certain lanes of movement.

Michael </font>

[Michael Emrys]

Originally posted by dalem:

I've never read of any German AARs or any anecdotal stories of taking indirect MG fire.

My sense of it is that it was less apt to be dramatically deadly. More a type of harassing fire than shooting for anihilation. If that is so, then it would have made less of an impression and less likely to make it into personal accounts.

One thing that has to be taken into account when reading personal accounts is the slant given by the individual's involvement. This sometimes manifests itself in funny ways. Some things get magnified far beyond their true stature and others, actually more important, get no mention at all.

For instance, Allied soldiers in the ETO claim always to be shot at by the dreaded 88. No one ever mentions the 105 howitzer, even though by far the majority of shells dropped on them were from that weapon. Similarly from the other side, one hears about the dreaded Jabos, even though those were responsible for little of the destruction or casualty count. Those items had a psychological impact reaching far beyond their material effects.

Michael

[ March 21, 2005, 01:17 AM: Message edited by: Michael Emrys ]

[Private Bluebottle]

Originally posted by dalem:

</font><blockquote>quote:</font><hr />Originally posted by Michael Emrys:

BTW, the reason the terms 'grazing fire' and 'beaten zone' were brought into this thread was to focus attention and provide a rationale for adopting a revised model for MGs in CM. It is felt by many that the effects as described in CM are too limited. For instance, an MG set up to employ grazing fire can interdict movement across its LOF all along that LOF and not just in one spot along it. That is a significant difference.

Michael

Doesn't it also limit the effectiveness of the CW Vickers platoons/companies? I'm not a big CW WWII guy so the concept still boggles my simple mind, but weren't the Vickers platoons more likely to be using some form of long ranged indirect fire than not?

-dale </font>

[pamak1970]

Which might be one big reason why the Vickers squads liked to use plunging fire. I am inclined to think that grazing fire was more of a defensive tactic, designed as I said earlier, to interdict certain lanes of movement.

I think i will agree on that.

I guess that during an offensive the fire support base and the MGs are in quite a distance from their targets.

At such big distances you can not have grazing effect since you need to have a firing angle in order to send the bullets there.

Therefore the trajectory from the MG is not low and parrallel to the ground level and does not affect all the troops along the LOF.

Somewhere i read that grazing range was in general up to 400 or up to 700 m depending on the type of MG.

Another thing as an attacker is that you are not able to choose the battlefield and therefore it is more difficult to find the opponent vulnerable to grazing effect.

So i think the combinatiuon of the two above issues makes difficult to acheive grazing fire during an attack

[pamak1970]

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[pamak1970]

It is interesting that there is not still any official comment regarding this aspect of game engine, which seems that either it is too early ,either the designers are not sure if they shoud or should not deal with this aspect,either they have not read the topic yet.

[Michael Emrys]

Too early would get my money. Also, it may be a problem they have not formulated a solution for. Some of what Steve has said about the difficulties of calculating LOS may apply here as well, since grazing fire inevitably has to take into account irregularities in the ground.

Michael

[pamak1970]

Too early would get my money. Also, it may be a problem they have not formulated a solution for. Some of what Steve has said about the difficulties of calculating LOS may apply here as well, since grazing fire inevitably has to take into account irregularities in the ground.

On the other hand ,since the whole issue is related with LOF ,LOS calculations, it is linked with the main core of the engine.

This means that they have to make a decision from the beginning ,regarding if and how they will deal with this issue.

[Wartgamer]

An ideal examination of the math might reveal just how powerful a technique this is in reality.

Lets take the example of a man assaulting a position that a HMG is laying down a final protective fire across. The HMG fires 600 RPM. 10 per sec. The man is about 100 yards away, and is modeled as a width of 12 inches. He is moving at 5 mph (rushing) across the MGs front.

The math breaks down to a speed of 88 in/sec for the soldier.

We will take a 'laser' approach and 10 bullets a second are forming a line that he must cross.

Since his width will be in the 'line' for a greater period of time than his speed will allow between bullets, He is virtually guaranteed being 'hit'.

I was told by a math teacher, who served in a MG unit, that they would optimally want to aim about thigh-high. The combination of the two sweeping legs, with one always 'planted' combined to make the odds very bad for anyone rushing a position.

In reality, the bullets spread out due to variations in bullets, weapon vibration. But for 100-200 yards, this is very small for a tripod mounted fast firing gun. The German HMG using a MG42 may have fearsome is properly sited and emplaced (high rate of fire). I have seen these weapons fire (when sand bagged) and they do not jump as much as many think. Likewise, a water cooled gun is 'damped' by its liquid weight and heavy tripod. Japanese wave assaults were cut to pieces by properly used MGs. Aiming was not a factor. The Japanese aimed thier bodies at the 'laser'.

Slow firing guns should be taken into account. Low velocity bullets also decrease the 'graze' range.

[Michael Dorosh]

I would have thought knee high would be better, since any soldier foolish enough to go to ground in such a situation would be shot in the head as he went to cover.

[Wartgamer]

The lower extremity of the sweeping legs are actually very small (each lower leg diameter) combined with a rapid arc motion. This adds up to very small objects moving through the target areas at very fast speeds.

The thickness of the thigh, and its slower arc motion is much superior. Aiming at the knees means that gravity brings the bullets down. In other words, you could not be worse off trying to cover a front.

For a weapon firing at 2400 feet per second at a 0 degree 'flat' trajectory, and 1 yard off the ground, the effects of gravity will drive the bullets into the ground in less than a 1/2 second. This is only 300 yards or so. Thats where the beaten zone meets earth when firing on a flat terrain.

So the 'sweet' spot around the thighs will only be a certain gap along this grazing fire. Getting the weapon lower and firing at nearly ground level, and using some superelevation, extends the 'graze' and constitutes many heights along the way.

Just using a running crouch (running bent over), defeats many high rounds. Hitting the dirt is not a guaranteed shot to the head. Unless you are unlucky enough to lay down in the beaten zone, its probably a good idea to do this before actually getting into a enemy position that has grazing fire across the front.

An optimal piece of ground to use this on is NOT flat by the way. You would want a nice gentle rise along the grazing fire. Like shooting over a very gentle slope. Guns should graze both ways on either sides of the slope. The reason should be obvious.

[ March 21, 2005, 02:03 PM: Message edited by: Wartgamer ]

[John D Salt]

Originally posted by Private Bluebottle:

[snips]

"Grazing fire" BTW is I believe an American term. I've never heard it used in a Commonwealth context. "Enfilade" and "Defilade" are the terms we tended to use.

H'mmmyes, but they mean something different.

All the best,

John.

[Simon Fox]

Bren gunners were specifically taught to use plunging fire against units in defilade too.

Another example of CW tactical superiority over hidebound sit in yer foxhole and blaze away with buckets of lead.

[dalem]

Originally posted by Simon Fox:

Bren gunners were specifically taught to use plunging fire against units in defilade too.

Another example of CW tactical superiority over hidebound sit in yer foxhole and blaze away with buckets of lead.

How dare you mention Commonwealth soldiery! You are polluting this thread with your Commonwealth pollutive pollutionness!!

-polluted dale

[Wartgamer]

Dalem

A pollutant without a country

[Simon Fox]

Originally posted by dalem:

How dare you mention Commonwealth soldiery! You are polluting this thread with your Commonwealth pollutive pollutionness!!

So, as a consequence of your deep insecurity regarding all things Commonwealth can I expect to be regaled with endless google derived nonsense?

[dalem]

Originally posted by Simon Fox:

</font><blockquote>quote:</font><hr />Originally posted by dalem:

How dare you mention Commonwealth soldiery! You are polluting this thread with your Commonwealth pollutive pollutionness!!

So, as a consequence of your deep insecurity regarding all things Commonwealth can I expect to be regaled with endless google derived nonsense? </font>

[Private Bluebottle]

Originally posted by John D Salt:

</font><blockquote>quote:</font><hr />Originally posted by Private Bluebottle:

[snips]

"Grazing fire" BTW is I believe an American term. I've never heard it used in a Commonwealth context. "Enfilade" and "Defilade" are the terms we tended to use.

H'mmmyes, but they mean something different.

All the best,

John. </font>

[John D Salt]

Originally posted by Private Bluebottle:

</font><blockquote>quote:</font><hr />Originally posted by John D Salt:

</font><blockquote>quote:</font><hr />Originally posted by Private Bluebottle:

[snips]

"Grazing fire" BTW is I believe an American term. I've never heard it used in a Commonwealth context. "Enfilade" and "Defilade" are the terms we tended to use.

H'mmmyes, but they mean something different.

All the best,

John. </font>

[c3k]

Gents,

All commonwealth references aside, grazing fire can be very effective. I'm speaking to those who contend that just by ducking under the height of the graze-line, one may render it ineffective.

If the trajectory extends from knee high to waist high, yes, you can get under it by crawling. As a defender, sure, I'd love to mow down row after row of onrushing attacker. If they resort to crawling, well, so much the better. Now they've stuck themselves in my kill-sack. (Self evident due to the fact that my machine guns have been sighted into that zone for grazing fire.) Now all I need to do is call in some arty, or let my armored support take them under fire from the flank, or etc., etc.

You get the picture. If grazing fire immobilizes an attacking force, it achieves a great deal of the defender's purpose.

Enfilade, Defilade, Grazing, Plunging: all different words for different concepts.

Regards,

Ken

[Aco4bn187inf]

Anybody ever heard of the US quad .50 cal used as an indirect fire weapon? They used it that way in Vietnam. I wonder if it was used that way in WWII as well, and if it could be in CMX2?

(Not holding my breath waiting to see that, though.)

[Wartgamer]

The point about hitting the dirt is to allow covering weapons to take on the MGs. An infantry assault would have covering fire that might include its own MGs or direct fire Tanks/Assault guns, etc that would engage the defending MGs once they halted the attack.

[Aco4bn187inf]

Oh, also- I understand that in real life, generally, snipers benefit most from being placed high up in buildings and MG's at ground level, to get the greatest effect out of their firepower. If the game could model the grazing/plunging issue just well enough to reward realistic decisions like that, I would be satisfied.

I seem to recall that Squad Leader allowed machine gun fire to affect a column of three hexes. (120 meters) Maybe not a bad abstraction for a complex issue.

I recall killing nine cavalry squads in a street that way, with one blast from an MG. But that was another lifetime...

[Michael Emrys]

Originally posted by aco4bn187inf:

Anybody ever heard of the US quad .50 cal used as an indirect fire weapon? They used it that way in Vietnam. I wonder if it was used that way in WWII as well, and if it could be in CMX2?

(Not holding my breath waiting to see that, though.)

I've read of it being done in Korea.

Michael

[Michael Emrys]

Originally posted by aco4bn187inf:

I seem to recall that Squad Leader allowed machine gun fire to affect a column of three hexes. (120 meters) Maybe not a bad abstraction for a complex issue.

I recall killing nine cavalry squads in a street that way, with one blast from an MG. But that was another lifetime...

I can't speak to ASL, but in the original SL, an MG's penetration in hexes was equal to its FP factor. So an LMG could effect a maximum of two hexes, an MMG four, and an HMG six. I recall once gleefully wiping out an entire company of Soviet infantry that way. My opponent gave up the game in disgust. It spoiled his whole day.

Michael