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240mm artillery very slow - bug?


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For the first time, I'm allowed to use 240mm howitzers, but they don't seem to fire corectly. I give the fire-order during setup, but when the game starts, I get the first 2 shells delivered very fast, then a delay of about 2 minutes, then the next two, then another huge delay.. and so on.

On the info screen for the howitzers, it shows "firing 63 minutes", though they only have 30 shells in all, and I asked for maximum rate of fire. What gives?

Is it because of the matchup level of the spotters? They are a dedicated FO team, but a red cross is desplayed for their matchup level. If their job is specifically to call in this artillery asset, shouldn't they have at least a decent level to match?

The very heavy mortars I also have on this map fire their barrage just fine.

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Them shells are heavy... Much heavier than mortar bombs. Wikipedia gives a RoF of 30 rounds per hour. I don't imagine it's a bug; it does the same for me. RoF doesn't depend on the FO, AFAIK, it's to do with how difficult the gun is to load and lay. Note that "Maximum" refers to the length of the bombardment, not its weight. I was getting less than a round every 2 minutes on Heavy, so I suspect you had set Heavy, Maximum; I mention it for future reference.

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Well, if it takes 63 minutes to fire 30 shells, that'd be about 2 minutes per shell. So, it seems to be modeled that the firing rate of 240mm Howitzer is 1 shell per 2 minute per gun, gradually slowing to 1 shell per 4 minute?

I have no idea if that is correct. I will note that 240mm is about 9 1/2". That's larger then most naval weaponry. This is being fired from a mobile field mount with hand loaded ammunition. (Naval weaponry has all the bells and whistles associated with a fixed mounting location: hydraulics, hoists, elevators, ready ammo, HUGE teams of men to service the weapon, vertically stacked ammo feed mechanisms, etc.)

An artillery grog (or a search) may turn up expected rates of fire. How heavy are those shells? How many men serve the weapon? What does the manual say?

Ken

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Thank you, and yes, "Heavy" rate of fire in game-terms (=the maximum rate of fire), plus "Maximum" duration.

Seems I had underestimated just how heavy those shells really are. 160kg!

But somehow, even a direct hit doesn't destroy even a medium sized bit of hedgerow, even though it's left hanging in empty space across the enormous shell hole. That seems a bit silly :)

What's the best way to use the 240mm guns? A "heavy" line mission with both guns, or a "medium" with just one gun, point target, and adjusting the mission as requiered as targets pop up?

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...

But somehow, even a direct hit doesn't destroy even a medium sized bit of hedgerow, even though it's left hanging in empty space across the enormous shell hole. That seems a bit silly :)

...

That sounds like a bit of a bug.

Possibly hedgerow is coded to need a number of hits to destroy and one hit doesn't do it ( even though a bang that size should, you'd think )

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Possibly hedgerow is coded to need a number of hits to destroy and one hit doesn't do it ( even though a bang that size should, you'd think )

Bocage Hedge can be destructed ONLY by demo charges or Rhino-Tank. Not by shells. Never; regardless of the size or quantity

(May be by Halley's Comet too if it hits right on target)

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Bocage Hedge can be destructed ONLY by demo charges or Rhino-Tank. Not by shells. Never; regardless of the size or quantity

(May be by Halley's Comet too if it hits right on target)

I didn't know that - was under the impression that a LOT of HE could do it ( ie. the bulk of 1 or 2 Shermans' HE load ). I may have misremembered a thread on the subject.

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What's the best way to use the 240mm guns?

Guns that big are not intended to be used for sniping fast moving targets like infantry, the way you might use 25 pdrs or 105 mm. They are intended to be used against heavy fixed installations, like fortresses, where you have all day to break them down. Of course that also makes them good for your urban renewal projects too.

I don't know the scenario in which they appear, but if it involves taking down field fortifications or fighting in a built up area, you're in business. If you are trying to defend against a Panzer attack, it's the wrong tool.

Michael

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Bocage Hedge can be destructed ONLY by demo charges or Rhino-Tank. Not by shells. Never; regardless of the size or quantity

(May be by Halley's Comet too if it hits right on target)

Nope; incorrect. Shortly after CMBN was released, somebody did tests and discovered it takes roughly a full load of 75mm HE shells from a Sherman (~50 rounds) to blow a gap in bocage. Just to make sure this was still correct, I re-tested in 2.01: 59 75mm HE shells from 2 Shermans to open up a small (infantry-sized) gap. 78 shells to open a full-size (vehicle) gap.

IIRC, the results are highly variable. A lot of shells fly right through the bocage and presumably these cause little to no damage to the hedgerow. Hypothetically, if it were possible to tell the tank to target with the intention of blasting a hole, it would probably take less rounds.

Not that I recommend this as a tactic; DF HE is a scarce resource and there are generally much better targets for it than holly bushes. Maybe rarely if you have a big HE chucker with deep ammo reserves like a Priest, it might be worth considering.

EDIT: And yeah... a single 240mm shell should definitely open up a gap in bocage if it lands on or near the hedgerow. Something's not quite right there. It's probably something the BFC didn't really consider or test much. Really big artillery like 240mm is mostly out of CM's scale. As noted, it's mostly for reducing heavy fortifications and to a lesser extent for deep interdiction/suppression fires. So it's fun to play with, but not all that realistic for it to be depicted in CM in the first place.

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Another note:

The limiting factor on sustained ROF for very large guns like this tends to be overheating, not reload or laying time.

Once the gun is laid in, it pretty much just stays there. Small adjustments occasionally need to be made between shots to account for things like barrel wear or changing conditions (e.g., temperature, wind direction and velocity), but these don't usually take very long for a skilled FDC and gun crew to execute.

And once the charge is known, shells and charges can be prepped well ahead of time; the prep team will have the shell and charge lined up, ready for the load team. Sure, the projectiles are quite large, but guns like this generally operate with a large crew who are well trained at moving the projectiles as a team. Theoretically, a full crew could get the gun up to a pretty high ROF; much higher than 1 rnd/2min. Many hands make light work.

But the heat generated by firing... well, there's not much that can be done about that. At best, you get 2-3 shells off on "rapid" fire before the chamber & barrel become hot enough to start affecting accuracy. Firing the gun when hot also increases the rate of barrel wear. Theoretically, if the ROF is pushed for long enough, at some point you'd get a premature cook-off in the chamber, which would destroy the gun and probably everyone around it. Practically speaking, though, you pretty much never hear of this happening as the overheating causes the accuracy of the gun to go to hell long before there's risk of cook-off.

So this is why you see the behavior in the game that you do on "Maximum" ROF -- a couple of shells fairly close together at the start of the shoot, when the barrel is cold, and then settling into a much lower sustained ROF, to give the barrel time to cool between shots.

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I found a july 1945 article on the U.S. 240 mm howitzer which shows the RoF at 2-3 shells every 2 minutes. However, when you look at its size and the loading procedure (the shell alone weighs 360 lbs. and the 90lbs bag of powder is loaded separately), that is probably a theoretical maximum.

http://books.google.ca/books?id=PiEDAAAAMBAJ&pg=PA76&dq=popular+science+1945+%22Biggest+Gun+On+Wheels%22&hl=en&ei=_erMTJrSG4Gknwf_vIkn&sa=X&oi=book_result&ct=result&redir_esc=y#v=onepage&q=popular%20science%201945%20%22Biggest%20Gun%20On%20Wheels%22&f=false

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I found a july 1945 article on the U.S. 240 mm howitzer which shows the RoF at 2-3 shells every 2 minutes. However, when you look at its size and the loading procedure (the shell alone weighs 360 lbs. and the 90lbs bag of powder is loaded separately), that is probably a theoretical maximum.

Yeah; that's probably the "burst" ROF. IOW, with advance planning and preparation, a well-trained coordinated crew can get off 2-3 shells within two minutes, but then it needs to slow down to avoid overheating, and the 30 shells/hr. figure from Wikipedia is the ROF it can sustain more or less indefinitely.

Couldn't say for sure if this is accurate without seeing the relevant FM or TM (I honestly wouldn't consider Popular Mechanics a much more reliable source than Wikipedia), but the two sources are not necessarily contradictory and these figures seem in the right ballpark for a gun of this type.

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Guns that big are not intended to be used for sniping fast moving targets like infantry, the way you might use 25 pdrs or 105 mm. They are intended to be used against heavy fixed installations [...] If you are trying to defend against a Panzer attack, it's the wrong tool.

Michael

I didn't mean using it like that, but was asking if it's better to order a heavy barrage at a line target before the map starts, or to initiate a slower point barrage that can later be adjusted to fire at new targets, such as bunkers, as they are spotted by the troops on the ground?

Rationale being: It takes a long long time to call in these guns once you're in the fight, so might be clever to pre-register some targets. But then again, you dont exactly know where the enemy fortifications will be.

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I'd think these monsters would (in the run of CM things) be best fired as preplanned missions at large built-up areas that are an eventual objective. They seem like overkill on the sort of fortifications we generally encounter and using them "ad hoc" is almost an oxymoron, with their call times. Hence using them pre-planned, since you might not be able to get LOS on the centre of your target until either it's too late for them to have any widespread effect, or you're too close to risk it.

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Yeah...IRL, when a weapon was used at the CM scale, it was done very slowly and methodically: E.g., Send patrols and probing attacks out to find enemy fortifications, and, once exact locations discovered, pull back and move an FO up to a position with LOS to the enemy fortifications. Then blast away, correcting aim after every shell or two, until a direct hit is scored. Rinse and repeat.

The 240mm howitzer had a reputation of being a very accurate weapon, and given enough time and good observation it could literally drop a shell directly onto an individual bunker in a relatively small number of attempts.

But I’ve never played a 4-hour long scenario where I was given an FO, a 240mm battery and some recon units, with the objective of finding and then knocking out three concrete bunkers, or something like this.

I dunno... I've never played a scenario where I was given 240mm, but if I had it, I'd probably just pick a particularly nasty looking section of defensive terrain and blast the crap out of it with a pre-planned barrage: A group of heavy buildings with good LOS/LOF, a section of heavy woods that I couldn't bypass, whatever.

And I wouldn't worry about using all of the shells. Unless it was a really long scenario, I'd probably plan a Short, or at most a Medium length pre-planned barrage, and figure that's about what I was going to get out of it. It takes so long to re-target and the danger close is so large that getting more than one target out of it in most CM scenarios is going to be a challenge.

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I'd think these monsters would (in the run of CM things) be best fired as preplanned missions at large built-up areas that are an eventual objective. They seem like overkill on the sort of fortifications we generally encounter and using them "ad hoc" is almost an oxymoron, with their call times. Hence using them pre-planned, since you might not be able to get LOS on the centre of your target until either it's too late for them to have any widespread effect, or you're too close to risk it.

All of the above. Seems to me that against most of the kinds of field fortifications encountered in CM, 150 mm or thereabouts is as big as you are likely to need or will be handy enough to use.

The 240 mm, and similar large gun arty, are kind of odd for the CM battlefield. I'd guess that BFC put them in the game kind of as one of those "for the heck of it" additions. They are available for those unusual situations where they might have come into play, but not at all standard for this level of combat.

Michael

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The 240mm howitzer had a reputation of being a very accurate weapon...

The brief test I did to see if the slow RoF was atypical certainly seems to show this being true for the CM system. I used a point pre-planned target and the shells seemed to be landing within an AS or 2 (I didn't squint at it very hard) of the aim point.

But I’ve never played a 4-hour long scenario where I was given an FO, a 240mm battery and some recon units, with the objective of finding and then knocking out three concrete bunkers, or something like this.

I think that'd make quite a good "vs AI" premise for a scenario. You'd be racing time, rather than looking to destroy all the enemy.

And I wouldn't worry about using all of the shells. Unless it was a really long scenario, I'd probably plan a Short, or at most a Medium length pre-planned barrage, and figure that's about what I was going to get out of it. It takes so long to re-target and the danger close is so large that getting more than one target out of it in most CM scenarios is going to be a challenge.

Interesting. I'd pick a "Maximum" mission, because you can always cancel it if you can't adjust it, and with the slow RoF, you'd not "waste" much ammo while adjusting. And seeing just how accurate the guns are, if you're using point target for something like a bunker, danger close might not be that close, if you've got something like Bocage to cower behind.

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Interesting. I'd pick a "Maximum" mission, because you can always cancel it if you can't adjust it, and with the slow RoF, you'd not "waste" much ammo while adjusting. And seeing just how accurate the guns are, if you're using point target for something like a bunker, danger close might not be that close, if you've got something like Bocage to cower behind.

Hm. Yeah... that's not a bad idea. Especially if it was a scenario where I was pretty sure I'd be running into concrete bunkers, and I had at least a vague idea where they might be at the start of the fight (which would probably usually be the case -- it would be pretty rare to run into this kind of heavy fortification without having at least a general idea of where they were).

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The problem with this particular mission is that I am given a briefing about enemy fortifications being located generally in a line at a specific place on the map. But I don't know where each bunker will be.

Now, I had to restart the map a couple of times within a couple of turns, for various reasons (I don't usually do this), so I know where two of the bunkers are. But I don't want to use this ill-gotten information, I feel it would be cheating.

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If you want to know the service of the piece for the Howitzer 240-mm M1, then are you in for a treat. The complete how to for the beast, to include fuze setting, mandatory bore swabbing (after 20 rounds) and much more. ROF data may or may not be in this. so far, no joy. Sustained rate isn't merely based on howitzer overheating, but also in large measure on the ability of the crew to simply keep going on the brutally demanding job (for the loaders and ammunition haulers) of feeding the monster. Continuously for as long as is required by the fire plan.

http://digital.library.unt.edu/ark:/67531/metadc11813/m1/1/

Regards,

John Kettler

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YankeeDog,

Destruction of a tough pillbox or bunker would typically be done using a single howitzer for precision fire. Where a 100 meter bracket was good enough for FFE for field artillery, this was a matter of progressively walking the shells onto the target, with the goal of demolishing it, or at least crippling it with Fuze, Delay shells.

Regards,

John Kettler

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Would this mission be 'Le Ham'? ;)

Yes! No spoilers please :)

But I would like to ask you about the briefing: It says there are minefields "to the north and south of your deployment area", but also that the enemy defensive line runs between the minefields. As the enemy line clearly runs east/west, I suppose the briefing should be "There are minefields to the east and west of your deployment area"?

Also, the village on the map is called "Le Val", not "Le Ham". The briefing says the plan is to overcome the defensive line and then direct artillery on Le Ham from the high ground. Is this something I am supposed to imagine will happen after the battle (maybe in the next map), as there doesn't seem to be any high ground on this map, at least not with much usable line of sight (due to hedgerows and trees)...?

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Nope; incorrect. Shortly after CMBN was released, somebody did tests and discovered it takes roughly a full load of 75mm HE shells from a Sherman (~50 rounds) to blow a gap in bocage. Just to make sure this was still correct, I re-tested in 2.01: 59 75mm HE shells from 2 Shermans to open up a small (infantry-sized) gap. 78 shells to open a full-size (vehicle) gap.

You're right. Sorry for my false information.

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But I would like to ask you about the briefing: It says there are minefields "to the north and south of your deployment area", but also that the enemy defensive line runs between the minefields. As the enemy line clearly runs east/west, I suppose the briefing should be "There are minefields to the east and west of your deployment area"?

I might have gotten a bit confused with the angles it's not using the real world orientation. To keep it logical with the other maps, I ran it from North to South rather than from East to West. I'll change the briefing to say left and right.

Also, the village on the map is called "Le Val", not "Le Ham".

The front part of the village appears to be called Le Val and I went with the 'real' name.

The briefing says the plan is to overcome the defensive line and then direct artillery on Le Ham from the high ground. Is this something I am supposed to imagine will happen after the battle (maybe in the next map), as there doesn't seem to be any high ground on this map, at least not with much usable line of sight (due to hedgerows and trees)...?

There are not many good locations on the map from which to observe Le Ham. However, you do have a couple of lovely TRPs ;)

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