Is Stuart/Honey gun overmodelled in CMAK?

[Michael Emrys]

Originally posted by Bigduke6:

Maybe what I am getting at is that all other things being equal it's easier to get a smaller round to a higher velocity...

If by "smaller", all you mean is less massive, yes that's true in the sense that it takes less propellant to accelerate it to a given velocity.

...and so increases accuracy at longer ranges.

That's sort of true but very imprecise. You might be closer if you substitute "chance of hitting" for "accuracy". A massive, slow round can be as or even more accurate—in the sense of consistently placing rounds on a small target—as a less massive, fast round, especially at long range.

But perhaps all this is getting more complicated than you want to take it? Simplifying, I would say that a very dense, projectile of low frontal area and excellent aerodynamic properties traveling at the highest practical velocities is the way to go. And that seems to be what weapons design has evolved to.

Michael

[JasonC]

Yes of course I should have used r and used d instead, my bad. All the figures are proportionally low, by a constant factor of 4, as a result. The relationships to each other and to penetration ratings remain, since it affects them all, equally. Sorry for the confusion.

On the Russian 45mm, I suspect the designers heard reports of it failing against 1941 German mediums and figured those must have been failures against 30mm plate. Which I consider laughably unlikely, for a weapon of 400,000 joules. Most likely, such reports actually recorded failure against 50mm plate, which the Germans fielded e.g. on the fronts of Pz 38s, the newer III J shorts, StuGs, etc.

The theoretical penetration of the 45mm should have been enough to penetrate 50mm plate, at least at close range and flat angle. Maybe even 60mm or a little beyond it. But realistic conditions of some side angle, 500m range etc would easily have led to some failures, and if the ammo were even slightly under spec perhaps to general failure against 50mm plate under practically all combat shot conditions.

The fall off in penetration rating between 100m and 500m is also completely unbelievable. The improved 45L66 model 1942 version sees the rated penetration fall by more than half from 100m flat to 500m 30 degrees. You can't find such fall offs with other guns. It has all the signs of a deliberate neutering, probably due to misinterpreted combat reports that confused the plate the gun had trouble against.

We know, incidentally, that the 45L66 successfully penetrated Panthers from the side at typical combat ranges. It doesn't happen in CM. We've got Panther hulls reported in post Kursk surveys with holes that size in them. This is only the standard Russian light PAK for the whole war.

It is also noticable that the Russians phased out 45mm vehicles in favor of SU-76s once the Germans had transitioned their fleet to all 80mm fronts. That was the plate that made them obsolete, not 50mm stuff in 1942. Perhaps with bad 1941 ammo and before the upgrade from 46 to 66 calibers - but after both, it remained a perfectly servicable weapon against less than 80mm plate. Even against that thickness it was OK at close range when APCR was available. And as others have pointed out, the Russians did not suffer from the tungsten shortages the Germans had.

As for other ways the Russians are shortchanged, the standard 76mm they use in the mid war was as effective as the US short 75mm. The two are twins in energy terms, and both are comparable to the round from the Brit 25 pdr. Nobody even pretends the other two weren't effective against plain panzers.

German training manuals say 80mm front StuGs and StuHs were not protected against 76mm AP at ranges under 500m, and nobody had ever heard of the uberstug phenomenon before CMBB. (Good optics, low outline for stealth, strong gun, all obvious, but invulnerable front plate, nobody can find even claimed, anywhere).

Then there are the 85mm weapons in 1943, when they actually matter. Except in CM. "Ammo modeling" is the handwaving excuse. I call it an excuse because even the guy who researched the math of it all admitted long since that 85mm AP bouncing from 30+50 StuG fronts at 600m is just completely wrong.

Did the Russians prefer large calibers? Yes. Was it because they believed in battering and multiple hits? No. It was because they followed the standard predictions that all say high T/D - especially just getting it over 1 to 1 - vastly increases effective penetrating power. 76mm gets through 50mm plate, 85mm gets through 80mm plate, 122mm gets through 100mm plate. Without monster velocities being required.

Bigger caliber also means a more useful HE shell, and the Russians understood that fighting tanks is not the be-all and end-all of an AFV.

CM strongly penalizes rate of fire as soon as caliber exceeds typical German levels, without any decline within those levels. All the rounds are light enough to be manhandled easily, even 152s are. The designers were a bit confused about semi-fixed ammunition, in which the powder charges are cut and loaded back into the round in a separate ammo-prep step. This does not reduce ROF because it is already done for everything in the ready racks.

I've personally exceeded the ROF CM gives to 150mm guns by about a factor of 2, and I wasn't particular outstanding at it. ROF should not decline appreciably for 105mm stuff, and the ROF given to that caliber in the game is about right for the bigger 150mm stuff.

When coupled with the small round high velocity bias, the ROF bias and shell quality bias, and tank cower behaviors, all combine to produce a laughably one sided picture of tank dueling between the best weapons. Panthers win on every score and JS-2s lose out. It wasn't that way in reality.

Russians win in CMBB anyway by using quantity tactics and by relying on specialty items to counter cherry-picked German uberarmor - 57mms, SU-152s, Sturmoviks (themselves overmodeled, largely because some of the developers were flight sim fans and took air to ground kill claims too seriously). And by using their high quality infantry (PPsH modeling is generous, etc). I take mountain guns instead of 45mms because they can kill vanilla panzers from the side, and toss HE better. Etc.

The result of the modeling bugs is more armor dominance for the Germans than they enjoyed, but not so much so that Russian players can't adapt and overcome. Provided they aren't shoved into a rariety or one-sided "realism" straightjacket and forced to take only undermodeled items against only overmodeled ones.

[John Kettler]

Michael Emrys is absolutely correct that high MV per se doesn't necessarily guarantee accuracy. In fact, the British found that on their 15" gun for battleships the designed MV was so high it was causing barrel whip, throwing off gunnery accuracy at longer ranges. Reducing the charge slightly, so that MV dropped ~ 200 fps, restored accuracy at range, with only minuscule impact on penetration performance. Another possible example of this phenomenon is Suvorov's citing of the Russian tankers' views of the then radical 125mm smoothbore gun on the T-64, "the all-powerful gun that always misses." If ever barrel whip could be an issue, that would certainly seem a possibility for a long-barreled gun with an MV in excess of 5400 fps (1800 mps).

JasonC,

While I think you make many valid points in your argument as to deficiencies in Russian equipmnent modeling, I'm not at all convinced that your ROF achievement on what I'll guess is an M-109 or similar is necessarily applicable. Ammo handling on an SU/ISU-152 was, SOFAIK, entirely manual, with the projectile alone weighing roughly 90 pounds, whereas, from what I've seen the M-109 and similar systems have power ramming, and the really advanced systems have autoloaders. Such equipment can't help but shorten the reload time. I've watched good M-1 crews on Discovery Channel and the like who, with an ergonomically optimized fighting compartment and powered magazine door,

are putting aimed 120mm rounds downrange at the rate of one every five seconds. The ready racks on WW II Russian tanks and SUs are decidedly suboptimal by comparison, especially when you also factor in the cramped space available in which to actually work the gun. Am therefore concerned your comparison is one of apples with bananas.

Regards,

John Kettler

[MikeyD]

I once tried recreating a bizarre real world combat anecdote using the 37mm gun and the CMAK model fell short.

This anecdote happened during the Bulge battles. A 37mm armed Greyhound was stationed along a dark country road. they're surprised when a Tiger I cruises past in the darkness. The commander orders the driver to race after the Tiger. They quickly catch up to it and before the Tiger can swing its gun around on it they put a round through the rear into the engine.

I concocted a CMAK mini-scenario to try this out. I got my Greyhound to point-blank range and let loose with its 37mm gun. No penetration! As I blazed away the Tiger lazily swung his gun around and BOOM! If the 37mm gun is overmodelled in CMAK so is the Tiger I's arse-end

[SteveP]

Originally posted by MikeyD:

I once tried recreating a bizarre real world combat anecdote using the 37mm gun and the CMAK model fell short.

This anecdote happened during the Bulge battles. A 37mm armed Greyhound was stationed along a dark country road. they're surprised when a Tiger I cruises past in the darkness. The commander orders the driver to race after the Tiger. They quickly catch up to it and before the Tiger can swing its gun around on it they put a round through the rear into the engine.

I concocted a CMAK mini-scenario to try this out. I got my Greyhound to point-blank range and let loose with its 37mm gun. No penetration! As I blazed away the Tiger lazily swung his gun around and BOOM! If the 37mm gun is overmodelled in CMAK so is the Tiger I's arse-end

One of my strongest memories from playing CMBO was in the Villers-Bocage scenario, in which I killed a Tiger from the side with a Stuart (I even think it was Wittmann's Tiger, but my memory could be off on that one). Not being a WWII grog by any means (and still not), I was nevertheless a bit surprised. When I checked the penetration tables at the time, I remember thinking that it was plausible from that standpoint (the range was short). But it was probably implausible in historical terms.

Does any of this matter in terms of game satisfaction? On that score, I have one additional peeve to record. That is, the problem of tanks cowering when getting hit by one of these relatively small caliber AT weapons. The cowering is reasonable given CM physics, but it does create some strange battlefield performances.

[JasonC]

MikeyD - sorry, it is an urban legend not a combat report. The target tank was almost certainly just mis-IDed. I've personally tracked at least a dozen such stories and typically there wasn't a Tiger within 100 miles on the day of the engagement.

On M-109s, their loading is nothing high tech. The rounds weigh 100 lbs, marginally heavier than the SU-152. Yes the ram is hydraulic, but it is also slow to position and to work, and I've done it manually as well. It is if anything faster manually, but more cumbersome and tiring. (Main thing is the blasted rod gets in the way of everything).

It simply is not hard to service a field artillery piece in a vehicle interior. Would they get 1 round every 5 seconds? No, I said the rate should fall for the 150mm stuff, but about to the levels you see for 105s in the game. But 30 seconds - the game rate - is the firing cycle of a 16 inch battery on a battleship, and you'd have to be flicted to be stuck at that rate on a simple 6 inch gun.

There are manuals that give the ROF of the M109 at that level, but that is for sustained firing over hours, indirect. The limit there is not overheating the gun tube. In a direct fire kill or be killed engagement, nobody is going to wait and have a cigarette before firing the next round.

[Guest Mike]

Maybe eh 45mm was kept in service too long because the alternative 57mm models were too hard to make, and too expensive, and too heavy for infantry use?

The Russian battlefield has a table for penetrations for the 45mm tank gun which i assume approximates the earlier model anti-tank gun: http://www.battlefield.ru/index.php?option=com_content&task=view&id=131&Itemid=49〈=en

[JasonC]

They made 4000 57mms. 3 for every Tiger I.

Russian penetration figures are much less generous than western ones, reflecting a standard that the full round pass completely through the plate etc. Western comparable figures would be 10% higher at least.

Yes it is the early model, as it specifies 46 calibers. It is also plain AP. That was the prewar version and the version used in the prewar light tanks. The 1942 towed version was 66 calibers, 50% longer, and that is the one that remained in service to the end of the war. Using APCR to remain competitive, late.

[MikeyD]

I once read 'somewhere' on the internet that the Russians were rather disappointed in the Lend-Lease Stuart because their own light tanks were more rationally designed, used diesel engines, and mounted the much more useful (according to this account) 45mm gun.

Another questionable factoid to add to the 37mm/45mm modeling debate

[ July 14, 2006, 11:09 AM: Message edited by: MikeyD ]

[John Kettler]

JasonC,

While I understand what you're saying about the M-109, with and without power rammer, the footage of I've seen of M-109 interiors during loading and firing and the shots I've seen of the inside of SU/ISU-152 emphatically, in my view, give an overwhelming ergonomic edge to the M-109. Indeed,

I'm not even sure there was room in the latter to even stand fully erect, which is not a problem in the M-109. I'd say the M-109 also has much better

ammo layout than the SU/ISU-152. Seems to me these would markedly impact the rate of fire.

I did some digging in Isby's WEAPONS & TACTICS OF THE SOVIET ARMY looking for ROF data for the SU/ISU-152. I found nothing for the SUs per se, but page 273 lists the max rate of fire for the ML-20 152mm howitzer (the armament for the SU) as

3-4 rpm. Data I've seen indicate that the ROF for

a towed gun is always better than for the same weapon installed in an AFV, for the very good reason there's more room to work the gun. I also checked Milsom's RUSSIAN TANKS 1917-1970 and Zaloga and Loop's SOVIET TANKS AND COMBAT VEHICLES 1946 TO THE PRESENT, with no joy in either place. Luckily for me, Russian Battlefield has semirecuperated from a major server crash earlier, and the SU-152 entry is online and in English. According to the article here

http://www.battlefield.ru/index.php?option=com_content&task=view&id=61&Itemid=50〈=en

the SU-152 suffered from a very slow rate of fire of (wait for it) 2 rpm, described as being caused by separate loading ammunition,and had a DF range of only 700m.

The related piece on the ISU-152 is also there, and it has a rather revealing interior shot showing the cramped working environment for the gun. I'll take the M-109!

http://www.battlefield.ru/index.php?option=com_content&task=view&id=40&Itemid=45〈=en

Regards,

John Kettler

[ July 14, 2006, 11:57 AM: Message edited by: John Kettler ]

[JasonC]

3-4 rpm is the right figure for either gun. And in CM, you get that with 105s - which in reality load as fast as smaller 3 inch guns, no difference whatever. It isn't a matter of space or ergonomics and it certainly isn't a matter of ammo prep. It is just the number of motions you have to go through and the time they take. 2 rpm is the right figure for sustained ROF for either gun, driven by cooling more than anything else - on a time scale of hours, crew fatigue would also matter.

[John Kettler]

JasonC,

Are reload cycle times in any way affected by crew quality? If so, what is the difference between, say, a Regular and a Crack crew in an SU-152 or ISU-152?

Also, per the second link, in Prussia an ISU-152 regiment (21 vehicles) was given an artillery mission, during which it expended 980 rounds in 107 minutes. My math tells me that works out to 9.16 rounds per minute, which is divided by 21, the number of vehicles presumably shooting, to

arrive at a whopping 0.44 rounds per minute, per vehicle. This is not even close to 2 rounds a minute, the sustained fire rate you gave. Of course, I'd be remiss if I failed to note that the average per vehicle ammo expenditure works out to 46.67 rounds, thus requiring remunitioning after preferentially expending on vehicle ammo (20 rounds max and not all HE Frag). From the links we know that the reload rate is as much as 2 minutes per round.

Regards,

John Kettler

[Guest Mike]

Depends what you mean by "load" - the French "75" could manage 20 rounds a minute for several minutes in 1905.

[JasonC]

JK - they can fire 2 per minute sustained readily. They aren't going to on a 2 hour long shoot. The mission is to suppress the target for 2 hours, not to fire the guns as fast as possible. Artillery batteries basically never fire max ROF for hours, because the ammo simply can't be brought to the guns that fast and it runs out if they do.

A few cases in Nam, with massive helo resupply to a few tubes as the only ones in range of a given battlefield, you will find sustained ROF over periods as long as 50 hours in which they averages 1 round every 2 minutes, but from 105s. That does not reflect continual firing at 1 per 2, but periods at 6 per minute and others quiet, or only half the guns firing, etc.

Non-gunners have this idea that max ROF is a real limiting factor for artillery batteries. It simply isn't. Max ROF hasn't mattered for sustained, long term firepower from any missile weapon from the longbow to the MLRS. Ammo is always scarcer than firing time. Always.

[JasonC]

JK - if that still isn't clear, understand the shoot you are describing means the unit in question threw 50 tons of ammunition at the enemy inside of 2 hours. Entire divisions in combat supply received on the order of 200 to 300 tons per day for all categories of supply, combined - not just ammo. Defensive rations were occasionally only half that. Some western mech formation occasionally got 500 per day for short periods as "attack supply" - but used most of it for POL.

[John Kettler]

JasonC,

I understand what you're saying, but I think you somehow missed the Russian Battlefield discussion of ISU-152 (by implication, also the SU-152) ROF. Valera's description (and he was a listed CMBB contributor) unambiguously says that the two SUs both suffered from a slow rate of fire, which was specifically listed in the case of the ISU-152 as 2 rounds per minute. Since you mounted an experience based argument as to the game ROF being wrong, I went looking for a data point in the available references and found it. Given Valera's access to primary and very good Russian secondary source material, I'm frankly inclined to listen to what he says. In the referenced shoot, even if I cede a higher ROF than I believe the evidence supports, you'd still run into a hard limit once on-vehicle stocks are exhausted and projectiles and charges have to be slowly handed in.

I said it before and now say it again: I think it's inappropriate to expect the ROF a cramped SU could generate to be even comparable to what a towed piece of the same caliber could do. To me, its like comparing apples with bananas.

Regards,

John Kettler

[SteveP]

Don't know if anyone will still be checking this thread, but I'm still not sure we have the whole story on why the Stuart and the U.S. 37mm AT gun are so much more effective in CM than in real life. I happened to notice something today that adds to the puzzlement.

The US forces in CMAK have the M15 AA halftrack with a gun which appears to be the same as the Stuart (both 37/54), but with significantly different penetrations (probably still too high, but more reasonable), which may be related to also having significantly lower velocity (for some reason). But why the difference in gun performance for what looks like the same gun?

The only difference I can see is the type of AP ammo (Stuart uses APCBC and the M15 uses APC). As I mentioned earlier, I'm not too clear on how the different ammo types affect performance, but is it possible that the Stuart and the 37mm AT gun are getting the benefit of a double overmodeling error: one related to velocity and caliber, and the other to ammo type?

Also, the Bofors 40mm AA gun (which uses AP shot) has a velocity not much lower than the 37mm AT gun, but significantly worse penetration ratings.

It's still quite confusing to me, I'm afraid. Anyone have any answers?

[JasonC]

JK - look in the US field manual for an M-109 SP howitzer, and you will find the ROF listed as 2 rounds a minute. But in practice, it isn't so. Similarly, an 88 will be listed as 6-8 rounds a minute, when in reality they sometimes hit 20.

[John D Salt]

Originally posted by SteveP:

[snips]

The US forces in CMAK have the M15 AA halftrack with a gun which appears to be the same as the Stuart (both 37/54), but with significantly different penetrations (probably still too high, but more reasonable), which may be related to also having significantly lower velocity (for some reason). But why the difference in gun performance for what looks like the same gun?

Well, that's an easy one -- they're different guns. The data that follow are stolen from R P Hunnicutt's "Half-Track: A History of American Semi-Tracked Vehicles" (Presidio, Novato, CA, 2001).

The gun in the M15 and M15A1 is the 37mm Automatic Gun M1A2, which fires the M59A1 APC-T shot. The Stuart's gun is the 37mm Gun M5 or M6, which is essentially the same as the ground-mounted M3, and fires the M51 APCBC-T shell or M74 AP-T shot.

Projectile weights, muzzle velocities and muzzle energies are as follows:

M59A1________1.91lb____2050 ft/sec____63 ft-tons

M51 or M74___1.92lb____2900 ft/sec____112 ft-tons

As you can see, the Stuart's gun has almost twice the muzzle energy of the automatic gun, so it's no surprise it penetrates better.

All the best,

John.

[John Kettler]

John D Salt,

I believe that the M1A2 may be the same gun as was fitted to the P-39 Aircobra and the P-63 Kingcobra.

There's a possibility, though, that I conflated a memory of that gun's being used on PT boats, a field installation I'm certain of.

Found this site, which is awash in good stuff, including M-15 data, but what I specifically needed isn't there.

http://afvdb.50megs.com/usa/index.html

Looks like I was right! From the Sarco, Inc.

online gun part catalogue (excerpt via Google)

Sarco #8393-01 11-20-03

File Format: PDF/Adobe Acrobat - View as HTML

Oldsmobile M9 37mm. Cannon – Receiver. demilled. Probably one. of a kind. For use on M15. half track or Bell Aero Cobra. Fighter. Also mounted as deck. guns ...

www.sarcoinc.com/6-20-06_pgs1-06.pdf - Similar pages

Regards,

John Kettler

[ July 20, 2006, 10:15 PM: Message edited by: John Kettler ]

[Michael Emrys]

Hmm. I've read that the deck guns were cast off Army (or possibly USMC) AT guns that were valued for their ability to penetrate armored barges. But I don't claim my source as a rock-solid authority. I suppose it might have been either one, or even both.

Michael

[SteveP]

Sorry to be so uninformed, but I guess my curiosity is still unsatisfied on this point. What exactly is it that accounts for significantly different muzzle velocities for guns that have the same dimension and are shooting ammo of essentially the same weight?

[John Kettler]

Michael Emrys,

Rather than either/or, we're both right. I've seen pictures of the ex-aircraft cannon with its characteristic semicircular magazine on a PT, and I've seen photos of the 37mm ATG, sans wheels, basically lashed to the deck. Speaking of PTs, this site is simply amazing. The Weaponry section has a 3-view of the ex-aircraft mount.

www.pt-boat.com

From a major PT site, here's another view of the same gun

http://www.ptboats.org/20-05-05-drawings-019.html

And a pic

http://www.ptboats.org/20-09-05-gallery-038.html

PT-109 had the 37mm ATG, on JFK's express orders

http://66.70.254.100/art/Hash/pt109/pt109project.html

Regards,

John Kettler

[ July 24, 2006, 01:35 PM: Message edited by: John Kettler ]

[John D Salt]

Originally posted by SteveP:

Sorry to be so uninformed, but I guess my curiosity is still unsatisfied on this point. What exactly is it that accounts for significantly different muzzle velocities for guns that have the same dimension and are shooting ammo of essentially the same weight?

More oomph from the propellant. According to Hunnicut (again), the Stuart's gun develops a chamber pressure of 50,000 p.s.i., the automatic gun a mere 36,000 p.s.i.

All the best,

John.

[SteveP]

Suppose I should have asked my question more carefully. Is the difference in performance between the Stuart gun and the AA gun because the Stuart gun is simply later technology, or because one is automatic, or because the difference in ammo type requires different propellant, or is there some military reason why one gun would be designed to shoot at a higher velocity (or, for that matter, why one gun would be designed to shoot at a lower velocity?

I realize that answering this may require informed speculation rather that categorical knowledge. And I also admit to just being curious -- it doesn't have much bearing on CM play.