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"Calling indirect artillery fire on a rapidly moving target" Topic


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775 hits since 20 Nov 2020
©1994-2020 Bill Armintrout
Comments or corrections?

Wolfhag Supporting Member of TMP20 Nov 2020 10:14 a.m. PST

I've heard a number of complaints from players about the unreal ability of indirect fire artillery to engage a rapidly moving vehicle formation.

If you model what is actually happening a formation moving at 25kph will move about 250m in 30 seconds which would be about the time of flight for medium or heavy artillery rounds. Now if that formation is a Target of Opportunity the battery would normally fire spotter rounds controlled by a Forward Observer. Now the moving formation could cooperate and maintain the same speed and direction but if they know they are being targeted they won't they change direction?

A larger beaten zone has a better chance of landing rounds within the formation but also a lesser chance of a round causing damage.

There is a lot of evidence of artillery lethality against tanks. A 155mm round landing within 30m of a tank can cause considerable damage. However, IIRC a British experiment showed a Churchill could survive a direct hit from a 25lbr.

https://imgur.com/gallery/gIjCo

Another problem I've noticed in miniatures games is that rule that plots where a round lands and then measures burst radius against the tank model because of the scale the tank's footprint could be 5-10x what it really would be.

A tactic that could work is if the battery has TRP's on chokepoints the enemy must pass through they could put up a nice rapid-fire barrage that the enemy formation must move through and time it right. But again, if it takes 30 seconds to move through the barrage zone a battery of four tubes is going to put out a maximum of 12 rounds in that time. If the formation is forced to move along a road or valley that restricts their lateral movement the battery could shift fire to keep them in the beaten zone. I don't recall the US or Britain using a ToT against a moving formation but with 30 tubes you'd be looking at maybe 70-80 rounds at the most which could be somewhat successful.

Modern cluster munitions and scatterable mines would be a solution.

Can anyone suggest any rules that can model the above?

Wolfhag

Stryderg20 Nov 2020 10:35 a.m. PST

Depends on how crunchy you want the rules to get. If you want to track humidity, temperature, number of rounds fired through each tube, etc, go for it. But I'm at a point in my life where simple is better. So…

Give the column a defensive bonus for being on the move and add in a potential collision rule if you want to make it spicy. Assuming they are on a road, changing direction probably isn't an option, but changing speed is. And if you do that in a column then you are going to end up with the slinky effect (spreading out over there and bunching up over here).

If moving in a formation over open land, I would guess that the commander would try to keep everyone in formation, otherwise you run the risk of collisions and ending up with a disorganized cluster once you get to where you are going.

Thresher01 Supporting Member of TMP20 Nov 2020 10:41 a.m. PST

Can't help on the rules, but as you mention, it's a lot different in open terrain like the desert than in the Fulda Gap, where movement is highly channelized and predictable.

Jcfrog Supporting Member of TMP20 Nov 2020 10:49 a.m. PST

My guess is if target on foot they would go to grond or dive in cover. So stop.
Armor might get partially blinded by dust , explosions and confusion, coukd slow ( you'd netter see the ground no to over turn in a ditch or lose direction.

79thPA Supporting Member of TMP20 Nov 2020 11:19 a.m. PST

I don't see an armor formation scattering to the wind in order to avoid artillery fire. I would think that they button up, and possibly change speed.

Sure, pre-plotted targets would be used if it was possible to do so.

BattlerBritain20 Nov 2020 11:29 a.m. PST

Also check how fast a formation would actually be moving.

For example in the Cavalry charge of British tanks during Goodwood in Normandy they were only advancing at 6km/hr.

So they might be moving slower than you'd think.

Eumelus Supporting Member of TMP20 Nov 2020 11:50 a.m. PST

I was Infantry and not Artillery branched, but spent some time at Ft Sill and in conversations I had with Artillery officers they didn't seem to think that even modern fire direction had much chance of damaging moving armor. The key then is to stop them from moving – for example with an AT ditch or minefield (preferably on a reverse slope so they don't see it until they're right on top of it) covered by pre-planned fires. If the enemy is obliging enough to stack up on a road with poor lateral exits (not actually uncommon in Korea, with very steep slope to one side and steep-banked stream or spongy rice-paddy to the other), then they can also be halted by stopping the lead vehicle. But the enemy is going to precede their attack with recce, so a lot depends on killing or blinding their scouts.

pfmodel20 Nov 2020 1:57 p.m. PST

Some rules use the concept of interdiction fire, basically indirect fire falling in a given location at low intensity which affects enemy (or anyone) moving through it. But as for fire support targeting enemy armour moving towards an observer, i suspect that will not be likley. The issue you raise is mainly a problem with rules which have a very small duration game-turn, 90 seconds or less. IN those cases an observer should take a few game-turns to call in fire support against a location, which means no issue. Rules such as Spearhead, with 30 min game-turns, may not have the same issue as well.

79thPA Supporting Member of TMP20 Nov 2020 4:23 p.m. PST

I just spoke with my brother, who was forward observer. He said you can call a time on target fire for effect mission on moving armor, and you can fire a spotting round and adjust fire on moving targets. He said a major issue is how fast the target is moving, and what the time scale of the game turn is.

Mobius20 Nov 2020 5:39 p.m. PST

25 kph = 25,000 meters in 60 minutes or 416 meters per minute or 208 meters per 30 seconds.
If artillery can hit moving ships it can hit moving tank formations.

A medium artillery shell will take about 20 seconds to reach 7,000-9,000 yards.

Skarper21 Nov 2020 1:54 a.m. PST

I think it's possible to hit moving units. For a game mechanic, secretly note the target and do not reveal it until the rounds land.

The British in WW2 NWE would kick high value target up the command chain and could end up firing an entire Corps artillery at times. The cumulative errors would cancel out.

Martin Rapier21 Nov 2020 2:06 a.m. PST

Good luck calling and correcting an ad hoc fire mission against a target travelling at 15kmh using WW2 technology. It is far more straightforward to either:

a) make the target stop with an obstacle as noted above
b) drop a large, static, defensive barrage in front of the thing which wants protecting. That is why they are are called barrages (the French for barrier)

Wrt artillery lethality vs AFVs it is only medium calibre HE (150mm) and up which is going to bother a tank, although lighter stuff will make it button up and obscure vision etc. Fire by a single battery is going to pretty much a waste of time against an armoured formation, an entire battalion or ideally, multiple firing battalions is much more scary. There are norms for this sort of thing iirc 18x122mm guns will knock out around 5% of fully armoured AFV in a 600m beaten zone in a five round per gun engagement (so approx 90 rounds fired).

Having said all that, no one likes being under shell fire, and I am often reminded of some footage of Saudi M60s in GW1, frantically reversing away under some pretty light artillery fire.

Jcfrog Supporting Member of TMP21 Nov 2020 2:56 a.m. PST

I remember my father who was a trained artillery officer in the 50s (esp F.O.o.) said they trained for that, mostly had ww2 105mm us. Mix explosive and what he called incendiary roubds. I might still have his instruction courses…

Andy ONeill21 Nov 2020 4:27 a.m. PST

I think asking a modern fo is fine for advice on ultra moderns. Ww2 is a different kettle of stoats though. Things changed a lot in the intervening years.

Expecting 105s to do anything but morale effect vs moving armour is a bit optimistic. Unless you have a LOT the targets will out the area of effect before you get to a percentile chance of physical effect.

Legion 421 Nov 2020 8:15 a.m. PST

Eumelus, I agreed and I was Infantry too. Was trained to call in FA, CAS, etc, also.

79th that is very accurate … and he was FA. So that works for me !

Yes, you'd have to adjust on the target(s).

For gaming purposes we, like many, use Burst Templates with varying sizes based on type of ordinance, etc. So you may still hit something just like in the RW.

And as always in depends on the length of a game turn, etc.

Another problem I've noticed in miniatures games is that rule that plots where a round lands and then measures burst radius against the tank model because of the scale the tank's footprint could be 5-10x what it really would be.
That may be one of the things you may have to accept as not always totally realistic. Again we KISS, the Burst Template(s) is a SWAG but not too far off generally … There is only so much you can simulate in a game. So I'm a fan of just coming close as you can't do much better on a gaming table. In some situations.

donlowry21 Nov 2020 9:11 a.m. PST

I've always played that the shells arrive at least 1 turn after you call for them (depending on how well linked your observer is to the guns/mortars), during which time the target supposedly moves somewhere else.

However, if the tanks are supporting an infantry attack, they probably aren't moving much faster than the infantry – 1-2 miles an hour!

advocate21 Nov 2020 9:50 a.m. PST

In Normandy (where lines might be fixed for a while and troop density was high) there are often reports of crossroads or stretches of road that were observed and the enemy would call down mortars at least upon vehicles that used the road. Vehicles throwing up too much dust were targeted. So indirect fire at moving targets happened, though often on pre-sited areas.

Personal logo Andrew Walters Supporting Member of TMP21 Nov 2020 10:31 a.m. PST

I've read a lot of WW2 artillery rules, but they all seem to be based on how people think things should work. They never match the feeling I get when I read accounts by the people actually calling in the artillery.

Games are supposed to be fun, so if you like you're artillery system don't sweat "realism". It's about evoking the history, not producing a simulation that produces reliable, usable results even if it's no fun.

My impressions from auto-biographical accounts include:

You're never 100% sure where they are, there's smoke, it's night, and if you only see two to four tanks is that all of them or is there a battalion?

When enemy tanks are far away they're screened by infantry, you don't know their location.

When enemy tanks are close they stop moving 25kph and move to fighting positions.

Most fire seems to be called down on pre-plotted locations. I don't recall anyone describing adjusting fire on a moving armor formation.

Hitting ships at sea is not a perfect comparison: ships have a lot of inertia and turn slowly, when they turn. Armor can stop in an instant and constantly turns to follow roads or avoid trees.

Mobius21 Nov 2020 11:13 a.m. PST

In the Audie Murphy movie he calls in artillery on advancing tanks and infantry.

UshCha21 Nov 2020 11:16 a.m. PST

A 155mm in an M109 in US service has a 2 round per minute rate of fire continuous, burst is about 4 RPM (for 3 min). By definition to get the yield they are relatively low velocity so not particularly accurate. The Brits consider AFV's that are proof against 155 shell splinters as 30m is effectively artillery proof. That is the odds of getting closer than that while moving is sufficiently remote as to be considered acceptable. Clearly although there would be more rounds if it was 88mm mortars, the danger zone is smaller so no real change in risk. Now the M109 carries only 28 rounds of 155m. How many will it risk on hitting a moving target its unlikely to hit. Reloading takes time, you don't park the vehicle next to a pile of 155mm ammo, you load one at a time from a distance so if it goes T*T's up you don't lose too much.

So 155 in a M109, would have to relay every round possibly as much as 250m, as as has been said the target moves significantly. Now every gun in the battery has to relay independently for optimum effect on one vehicle which is a major task, now each ones shot will be different if they all want to converge on one target point, or they can maintain the spread but then effectively any one vehicle is facing in effect only one gun. Now all is not quite lost, it is expected (its in the M1 manual) that the crew may need to replace the aerials as losing them is a likely outcome, so some potential for degraded communication. Similarly some damage to external may be possible as they are not that well protected.

Even in a direct fire role thay do not have the same Fire control as a 120mm armed tank and there dispersion is higher due to the low velocity so hit rate will not be that good.

Obviously a soft vehicle is far more at risk as the danger radius is much higher when considering a soft vehicle and the area covered is proportional to the Radius squared so the risk increases dramatically. I an mot covering that in this post

A number of books note tank commanders in WW2 considered driving through an artillery barrage as not particularly risky.

In our own rules we have been a bit generous an MBT will get some externals damage if in a beaten zone at a risk of 10%. No other damage is considered possible as risking more than Half a load of ammunition in a forlorne hope to hit a tank is considered not sensible so is not covered.

Again against a static vehicle more damage could be achieved however even then the density of fire is very high. for instance take the rule of thumb of 1/2% of range for the accuracy of a howitzer, at 3000m the error is plus or minus 15m so 3 rounds at least would be needed assuming the impact theoretical point was near perfect. In reality proably nearer 6 rounds and an individual very expert spotter to sence it in.

This looks at least plausible with Martins Rapiers assessment 90 rounds in a 600m target area. Now tanks NEVER get closer than 40m/50m if they can helps it. Now in combat or a road move they are likely to be 50 to 100m appart and in some form of line 600m so about about 7 tanks across. So 7 tanks in a line and maybe two lines if advancing say 400m appart, so 14 tanks, 5% KO rate gives about 0.7 of a tank knocked out for an 18 gun battery. I would suggest that in a typical game that is not going to be an issue.

Missed a bit, Tigers in Combat Pt 1 (Kindel version was 99p) note loss of a Tiger sent to defend a hill overnight. Trouble with a Tiger, it cant move all night so in the end will be a stationary target. Then a dedicated observer could spend time and ammo to finally get a very near miss or a hit to knock it out. We considered this beyond the scope of our rules but could be a scenario based rule but situation looks unappealing to play out.

CeruLucifus21 Nov 2020 3:20 p.m. PST

Mobius
In the Audie Murphy movie he calls in artillery on advancing tanks and infantry.
That's based on a scene from his autobiography To Hell And Back, and the action that earned his Medal of Honor. I just reviewed the book quickly.

There had been fighting for several days with Allied units advancing, being repelled, and Germans counterattacking. Murphy was stationed with a depleted company and an artillery observer waiting, actually, for reinforcements to stage an attack, or for a German counterattack. Their armor was 2 Tank Destroyers which were exposed on an elevated road -- Murphy told them to get into cover but their commander was the same rank and preferred the better line of sight.

The counterattack came in large force -- Murphy reported 6 tanks and at least 2 hundred infantry. It was preceded by a barrage which knocked out one Tank Destroyer and the machine gun squad. The other Tank Destroyer got stuck in a ditch and its crew bailed out. Murphy knew their position was lost and ordered the observer to withdraw so his radio wouldn't be captured. He also ordered his men to withdraw leaving him alone. He called in artillery by telephone and used map coordinates, ordering a smoke round, then adjusted fire. The Germans took cover but continued advancing. To keep them in the zone he took his telephone onto an abandoned burning Tank Destroyer and used its machine gun to slow down the advance. And walked the artillery back, finally calling fire onto his own position as he withdrew.

This episode covers many of the issues discussed above:
- the area had been surveyed and the artillery battery had map coordinates.
- communications were good – a phone line had been run.
- the battery was expecting to be called – they had sent an observer with radio to improve response time.
- the Allied barrage was still only effective because Murphy found a way to slow/hold the enemy down.
– with 2 Tank Destroyers in exposed stationary position, the German artillery only succeeded at hitting one.

Wolfhag Supporting Member of TMP21 Nov 2020 10:08 p.m. PST

Thanks for the feedback guys.

For modern artillery with GPS and laser rangefinders (can they read speed too) they should be able to call in a rapid-fire barrage almost any time. For WWII it would be at pre-sighted locations. Moving at 6kph appears to be a tank infantry operation. The problem arises attempting to engage fast-moving vehicles that have freedom of movement.

I agree with Martin. If artillery had time to set up and register guns from good maps (the Allies did from air recon photos) or have terrain reference points it would be much easier.

So no suggestions on game rules that can best represent the problem. Maybe something with 30 second turns?

Wolfhag

When my son was in the mid-east he saw a Saudi modern MPT tank crew bailout whn taken under fire by an RPK. It happens.

Martin Rapier22 Nov 2020 1:48 a.m. PST

"So no suggestions on game rules that can best represent the problem. Maybe something with 30 second turns"

In a tactical game with 30 second turns, it is going to take multiple turns for the fire mission to even arrive (assuming your comms are up and running), so you are back to either firing on pre registered points or the observer try to guess (several turns in advance) where the target is moving to.

Once the rounds are falling and assuming comms are still up I suppose you could try and walk the fire to follow the moving vehicles, but in such a short space of time I don't know how practical that is. Send an adjustment order, relay that to each gun crew, adjust the lay of the guns, fire the mission. All in 30 seconds?

I guess the fundamental issue is that you are trying to hit a moving point target with an area effect weapon. Anti tank guns work much better at this sort of thing!

Skarper22 Nov 2020 3:09 a.m. PST

For WW2, I think North Africa and in the East are the two theatres that armoured formations were able to move rapidly for long distances.

The Soviets were never good at 'on call' fire missions and mostly used artillery for bombardments and perhaps for defensive fires on pre-registered targets. [Such is my understanding anyway].

The Germans were quite slow and would not have the ammunition to engage moving targets efficiently.

The US could be very accurate but were also slow – it just takes time to do the maths even with some time saving aids. They also would not have encountered many fast moving AFV targets…

The British were able to pull off some coups in Normandy. Rauray was one engagement with a lot of artillery fire versus AFVs and it was effective. But I don't think they were moving very fast.

Post WW2, the emphasis on keeping AFVs moving is in part to avoid getting caught by artillery fire. Fire control and ranging and communications had come a long way, but the time of flight and greater speed of AFVs would still mean you'd have to guess where they will be up to a minute in advance…

Much better to use the scarce artillery ammunition on choke points, supply routes and softer targets.

Wolfhag Supporting Member of TMP22 Nov 2020 12:45 p.m. PST

I agree with everything people are saying. It appears to me, the real problem is timing which few games can faithfully portray.

My friend's issue was when the artillery phrase came the rules allowed his opponent to place a barrage template over his unit and roll for dispersion. Since the movement phase occurs before or after artillery the rules allowed his opponent to place an artillery template essentially as a static target and take the full effect of the barrage if the dispersion was minimal.

Wolfhag

Zephyr122 Nov 2020 9:31 p.m. PST

Plot where the barrage is to hit ("leading the target" as it were), calculate the time of flight (throw in some 'fog of war' delays if you're feeling mean ;-), hope the enemy drives into the target area. These actions should be hidden from the opposing player until they need to be resolved (announcing where a barrage is to hit, then waiting a few turns before it arrives kind of gives the opponent a chance to maneuver out of the way. Similarly, firing ranging rounds could tip them off, too, but that's the risk you take… ;-)

Andy ONeill23 Nov 2020 12:04 p.m. PST

Talking ww2 and imo – but also how we play.

You should at least randomise the delay. Roll per turn for the call to translate into effect. Pre plotted 80 mm mortar dropping in frint of trenches ought to be a lot faster than 155s.

Ww2, you usually couldn't see spotting rounds in forest or bua and often in rolling terrain without a fo in a plane.
And then the main asset on one side is that fo.

In the context of a tactical game.
It's not unreasonable to only allow arty fire on a very limited number of pre plotted points.

All this is very different from placing a template in a chosen ideal position over the ither player's models.
So i can rather see your friend's point wolf.

UshCha23 Nov 2020 11:43 p.m. PST

Ihere are some errors in the use of a templeate. The template is of itself and agregate in time. Now take martin Rapiers excelent information. (90 rounds from 18 guns). An M109 can fire max 4 rounds a minute, continious 1 or 2. So at a very optermistic level 1 min 15 sec between the start and the end and perhaps closer to 2 min 30 sec, Now takeing Wolfhags data at 25kph the tanks are through in 1 min 45 seconds. So actually there exposure to fire is very limited,unless they are stationary or moving very slowly. Again you could put the fire in the way and force potentially the tank to drive through it. However as pointed out even if they don't avoid it it has to be there before the tanks. That means for say the 155mm there rate of fire is max 4 RPM but if firing with a warm barrel 2 rpm. Again the tanks are through before the shoot has finished so minimal chance of a hit. It was only 5% to start with. To be honest where do you want to call time on the simulation? 18 gun batteries, 36 guns, 72 guns, 8 15" Navel guns. Perhaps they are designed for engaging moving targets but the naval parties don't have the kit tey have onboard for range, velocity and vector assessment and Vaval ships cant turn or slow down with any speed.

UshCha23 Nov 2020 11:56 p.m. PST

Ihere are some errors in the use of a templeate. The template is of itself and agregate in time. Now take martin Rapiers excelent information. (90 rounds from 18 guns). An M109 can fire max 4 rounds a minute, continious 1 or 2. So at a very optermistic level 1 min 15 sec between the start and the end and perhaps closer to 2 min 30 sec, Now takeing Wolfhags data at 25kph the tanks are through in 1 min 45 seconds. So actually there exposure to fire is very limited,unless they are stationary or moving very slowly. Again you could put the fire in the way and force potentially the tank to drive through it. However as pointed out even if they don't avoid it it has to be there before the tanks. That means for say the 155mm there rate of fire is max 4 RPM but if firing with a warm barrel 2 rpm. Again the tanks are through before the shoot has finished so minimal chance of a hit. It was only 5% to start with. To be honest where do you want to call time on the simulation? 18 gun batteries, 36 guns, 72 guns, 8 15" Navel guns. Navel are designed for engaging moving targets but the naval shore parties don't have the kit they have onboard for range, velocity and vector assessment and Naval ships can't turn or slow down with any speed.

donlowry24 Nov 2020 12:18 p.m. PST

Presumably you would want to hit the tanks with artillery fire while they are slowed down by mines, ditches, tank traps, ATGs, etc., not just motoring down the autobahn.

UshCha24 Nov 2020 12:40 p.m. PST

donlowry, That is the point, trying to ditches/anti tank traps would reduce speeds significantly IF they form a que. Otherwise how much ammunition are you prepared to put on individual machines trying to fill the ditch in several places at once.

Another interesting one would be an AFV mine clearing. It would be on its own but relatively slow moving and more predictable in movement than most vehicles. Now there is an added catch here. Real Minefields laid by real engineers can have areas within them, designed to allow the enemy to be shelled as they have no mines in them. Shelling your own minefield can reduce its effectiveness. This could maker it "interesting" as by shelling the clearing vehicle you may give the enemy a key to "unlock" the field. Once cleared then the enemy will be moving faster so much harder to hit.

Nobody said shelling AFV's was easy or even sensible, except some war games designers who never did their research ;-).

UshCha24 Nov 2020 12:55 p.m. PST

I felt I should put my money where my mouth was. I looked at our rules against Martin Rapiers real world case. For AFV's with a side Armour around or30mm more RHA equivalent the vehicle cannot be knocked out but has a limited chance (10% per vehicle) of damage to sights, external weapons and communications.

This is based on 48 rounds falling on an area 600m by 600m. Doubling the rounds would make the possibility of damage increase to 20%, but knock out is still not possible. Not perfect but to be honest for a rare event, I consider this an acceptable level of accuracy.

Wolfhag Supporting Member of TMP24 Nov 2020 1:59 p.m. PST

Thanks guys. I think my friend and I have figured out a workable way to portray the timing and interaction between a barrage and movement.

For WWII it normally going to be feasible calling in on a TRP, covered obstacles, or for FPF but then you're not going to use 155's for FPF.

Wolfhag

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