German 250/11 vs M2 Halftrack at 170 meters

[Treeburst155]

Here's an interesting figure from a test I ran. The 20mm on the 250/11 will average 3.7 HARMLESS penetrations of the M2 halftrack before firing the knockout round at 170 meters. This is when no fire is being returned by the M2 crews.

The average is based on 20 test instances involving about 140 rounds fired in total. I think I need to run one of my exhaustive 500 count tests on this one.

[Treeburst155]

I'm convinced now. No further testing required. You should figure on an average of 5-6 HITS on an M2 halftrack by the 20mm on a 250/11 at 180 meters to put the M2 out of action.

In my latest round of 20 trials, 3 M2s survived the entire minute, having endured 8, 9, and 11 penetrations respectively. The record holder so far survived 12 penetrations before being knocked out by round 13.

I've tested this 60 times now. The average number of harmless track hits, gun hits, and penetrations using Crack German crews at 180 meters was 4.1 per M2. Hits causing a casualty were NOT counted as a harmless hit. The vast majority of the harmless hits were hull penetrations with an occasional harmless gun or track hit.

So, when you nail that M2 halftrack with 3 or 4 penetrating rounds from a 250/11, and the thing keeps on tickin', don't be surprised, cuz the M2 can take a good 20mm lickin'.

[ January 21, 2004, 01:33 AM: Message edited by: Treeburst155 ]

[Abteilung]

Post penetration effects seem to be far too lenient on the crews of AFV's currently, imho.

The energy many of these rounds have left after perforating (projectile base completely passes through plate in question) is far more than adequate to cause grevious harm to the occupants.

One item which still bothers me is the number of actual perforations achieved by the auto-cannons. The magazine fed variety empties the whole clip on every "shot". How many of these actually count?

Another note is the APHE ammunition used by many auto-cannons. These were particulary troublesome to the crew, even when only partially penetrating, they stood to do damage to the occupants. Though this would apply more to the larger calibers (i.e. 75mm) than the auto-cannons, the thickness of armor generally engaged by such weapons would compensate, imo. There was a famous test of the german 75mm APHE round stuffed into an M2 and fired by the British ca. 1942 (T.C.N.A. - Tom Jentz). This test provided interesting results regarding the effectiveness of even a partial penetration by APHE.

Another point of contention are the Italian AFV's. There should be a lot more spall flying around in those things due to their armor quality. Don't get me wrong, it's not like they're uber-tanks or anything, but nonetheless, it strikes me as odd to see an M13/40 survive multiple penetrations from a 2pdr and still have most of the crew bail out alive.

Same with a tank whose ammo supply has been hit and detonated. I can't count how many points I've been erroneously awarded by a Sherman crew who steps out of a vehicle which has just recently exploded due to large caliber APHE penetration in the side lower hull. How it is possbile for someone to actually survive that, I would like to know. This just doesn't seem possible to me. While the gamer in me is grateful, the grog isn't and respectfully requests an explanation.

Edited because of my atrocious spelling and grammar. Apologies to those who tried to muddle through it the first time.

Edit: Part Deux

I ran the test a few times, but not enough to gather a meaningful statistic. I was, afterall, on lunch break. I ran over my alloted time by a bit, I might add.

Heh, oops.

I placed the HT's each 9 squares/tiles apart from each other at standard elevation (7, I think) and surrounded by rough to prevent all but the most local movement. The few times I ran the test, the German HT exhibited the same behavior, altough it did unnerve the other vehicles crew (affecting their morale state), it didn't do much else execpt for the fourth time I ran it, when I changed from side to front angles. That time the HT was hit frontally and lost the crew! The last two I was able to run achieved a mobility kill within 4 turns each, but not much else (crew wasn't happy and tried to back away from the German as much as it could) Also, the 20mm on the German HT seems to be not an auto cannon like the Kwk.38, rather it is the high velocity squeeze bore weapon. It is quite conceivable that the thing is so fast and small that unless it begins to ricochet around inside the vehicle, it will not likely hit something vital in a large open vehicle.

[ January 21, 2004, 06:11 AM: Message edited by: Abteilung ]

[Treeburst155]

The 250/11 fires tungsten exclusively. However, I'd bet that the same test run at, say 500 meters, would yield the same number of harmless penetrations before putting the vehicle out of action. Penetrations which caused a crew casualty were fairly rare compared to outright "no serious damage" penetrations also.

[ January 21, 2004, 01:52 AM: Message edited by: Treeburst155 ]

[Abteilung]

Originally posted by Treeburst155:

The 250/11 fires tungsten exclusively. However, I'd bet that the same test run at, say 500 meters, would yield the same amount of harmless penetrations before putting the vehicle out of action. Penetrations which caused a crew casualty were fairly rare compared to outright "no serious damage" penetrations also.

Ahh, I see. If that's the case, then the ammo type is most likely an APCR type round which has no explosive filler and would rely almost soley on post penetration contact with vital components and crew and/or spall to do it's killing. Still it stands to reason that after several magazines worth of tungsten shards spraying the interior (even if some rounds pass through harmlessly or exit through the open top), the crew would have been hit. There isn't a whole lot of room to hide in an AFV....

[tar]

Is this in part due to a large number of penetrations being in the (essentially empty) passenger compartment of the halftrack? It would take up a large part of the vehicle and have perhaps only a single crewman in it?

[Treeburst155]

You could be right, Tar. I don't know what is right. I just know what is.

[Abteilung]

I will go home for luch in a few minutes, so I will try and replicate your test a couple of times, treeburst155. Also, I would like to try some other 20mm ammo types. I remember in CMBB, the Pz.II would use HE rounds to good effect against the T-26 light tank. That was BB, though. Haven't run into Pz.II in any QB's yet, so I don't how the tac AI selects ammo in CMAK. Seems to not like using APCR too much, though. I often wonder why a PzIII would ricochet multiple rounds of APHE off a Valentine's mantle at ranges where one solid hit from APCR would penetrate and most likely cause harm to the tiny turreted val.

More obfuscation, I know, but it's been awhile since I've been here.

[Cpl Carrot]

Are the shot side on or frontal? I would have thought with frontal shots you have a greater chance on hitting the engine, than empty space.

[Steiner14]

Posted in the bug-thread.

[ January 21, 2004, 04:18 AM: Message edited by: Steiner14 ]

[flamingknives]

APCR will go straight through both sides of a US HT - it's only a total of about 15-20mm, allowing for some side angle. So unless there is something important along the line of the shot as it passes through, there won't be any damage.

I don't know if this is actually true, but I've heard that 7.92 rounds (most probably sMK - steel cored) will go through the plate on one side but not be able to get out the other. Cue ricochet mayhem. This jives with descriptions of 'K' ammunition in WWI ('K' ammo = sMK, as far as I can determine) vs. ~7mm armoured tanks.

[Joachim]

IIRC the 20mm on the 250/11 is not the autocannon but the "28mm ATR".

No test, but as I played that turns repeatedly, it might qualify.

The beginning of a scen I design has a column of M3 Scout cars, a Jeep MG and an M3 HT ambushed by 4 SdKfz 231 , 4 250/11 and 3 251/10 at ranges from 800-1200, 600-800 and 200-400 respectively.

Multiple hits and penetrations. It usually took 2 turns to finish the US patrol, at least half of the crews and passengers were alive. End of 2nd turn sees most of the US HTs ok, ending the game immediately afterwards sees all of them abandoned. In each occasion (had to test several times due to find out what takes so much computing time) the HTs got at least 5 hits from different angles till they decided to quit.

Effect of 3,7cm on 251/10 seemed much better, but harder to hit something.

The 231s scored more hits at longer ranges than the 250/11 due to having an autocannon. It took them one turn till they arrived in their firing positions, and 2 of them had to abandon positions after one turn due to long range Stuart and M3 GMC fire (at 2000m), but in turn 3 I shoot at dead horses anyway...

The 250/11 had almost no effect but forcing the US HTs to run around wildly. The HTs even returned fire and were able to suppress some 250/11s (before the 231s and 251s arrived)

Conclusions:

Effect after penetration of light guns is low. 20mm auto has some overall effect due to higher hit prob. But I'd like them to fire HE...

20/28mm smooth bore on 250/11 is a big ATR and works like an ATR. The target gets nervous, and a lucky hit might score. Intend to send them on the flank and shoot&scoot at sides of US armor. Wanna know what they can do vs tanks.

37mm gun on 251/11 doesn't hit that good, but it has some effect vs HTs.

Gruß

Joachim

[Sergei]

In a PBEM game with random forces I had a duel of halftracks - my Green 251/11 against American Elite M2 with .50 cal. They had a few clashes, usually both cowering away, until to my surprise the M2 was abandoned without having taken casualties! You wouldn't think MG-42 to have such effect on an Elite crew...

[Code13]

Playing CMBO I always found that in the absence of bigger guns the best thing to stop HT's with was HMG's.

Pretty much gaurantee that a .50 cal or MG42 will take out any HT or at least force them to abandon within a minute or two, close range it will just kill them.

some of these experiments would be interesting if the HT's had passengers, see what the effect on them is, you might see then a huge increase in carnage...

[CMplayer]

Originally posted by tar:

Is this in part due to a large number of penetrations being in the (essentially empty) passenger compartment of the halftrack? It would take up a large part of the vehicle and have perhaps only a single crewman in it?

You could test by loading a halftrack to the max with a squad and a small team or whatever, and redoing the test. See if there are more hits to the passengers.

[Dinsdale]

Another note is the APHE ammunition used by many auto-cannons. These were particulary troublesome to the crew, even when only partially penetrating, they stood to do damage to the occupants. Though this would apply more to the larger calibers (i.e. 75mm) than the auto-cannons, the thickness of armor generally engaged by such weapons would compensate, imo. There was a famous test of the german 75mm APHE round stuffed into an M2 and fired by the British ca. 1942 (T.C.N.A. - Tom Jentz). This test provided interesting results regarding the effectiveness of even a partial penetration by APHE

Froma friend who is a professional Kinetic energy AT Missile tester and WWII grognard.In reference to WWIIOnline APHE effects but info is still valid.

IMHO the effects of the burster charges are VASTLY overstated. Avg crew casualies per vehicle penetration by 1944 (read generally 75mm penetrations) should be a little over 2...probably around 2.3-2.4 given a fair hit. Average crew casualties for a 37mm should be alot less UNLESS ammunition explosion is induced (possible because ammo bins on early british AFV are not armored...the german bins are). Taking that into account, though, one would think the avg crew casualties for a clean 37mm penetration would be 1 or less...certainly NOT multiple crew casualties the way we currently see them in game.

Scotsman

And that is in a tight interior. Unlike a Halftrack.

[Treeburst155]

IIRC, the 20mm/28 ATR did quite well against Stuarts in "FlakFront!" This one was not mounted on a 250/11. It bounced quite a few, but it seemed to kill the Stuarts as quickly as it will kill the M2 halftrack, maybe faster.

I'd have to do some testing to verify this.

[MikeyD]

"I don't know if this is actually true, but I've heard that 7.92 rounds (most probably sMK - steel cored) will go through the plate on one side..."

I'm reminded of an anecdote told me by an old WWII veteran. His company had landed for the first time on some Pacific island (Pelelu?) and the Company commander was giving an orientation speech in front of a halftrack. He was cautioning them not to grow too attached to the halftrack during a firefight, and to illustrate the point he suddenly drew his .45 Colt and plugged a hole right through the armor to the great alarm of the troops! After that nobody in the company relied on their halftrack for easy cover again.

[JasonC]

It is a different sort of vehicle, but also one much more sensitive to loss of certain parts, but I think the following information is still useful when thinking about small caliber penetrations and what they do. The Germans analysed how many hits by rounds of various guns it took to knock down a B-17 or B-24. With the 20mm, the answer was 20, on average. They moved to the 30mm on fighters late in the war because that was thought too high. With their 30mm it was only 4-5.

[Abteilung]

Dinsdale: WWIIOnline uses a physics based model for ballistics and armor penetration. While this approach is superior to others in the accuracy which theoretically can be achieved, it is not practical in the vast amount of resource the calculations consume. This means that in an environment such as a MMOFPS, it is technologically impossible to achieve accurate results currently using a physics based model. There are too many crucial factors at play which when put together in a simulation (someday we can all hope), could achieve believable results.

Alone, or in part, they will simply create odd anomalies and completly off-the-charts performance. I can understand why Scotsman is reporting oddness in performance in that game. My own experience led to results too wildly unpredictable to be even remotely believable. Wasn't too long before the shoot-em-up spawn-camp fest got to me as well and the whole affair lost its appeal. That's just my opinion, though.

In any case, the tiny little tungsten round fired by the lePak on the 250/11 (and 221 late) seems to fail to hit anything vital on it's way through as per all of the comments read thus far and my own experience. It travels at 1200+ m/s, iirc.

Using the weapon on an AFV which would present armor too thick to pass completely through the vehicle results in similar occurences. Using a Valentine III as a target ends up about the same as the M2, given the Val is close enough to perforate. Didn't try a Sherman against it. Not sure how much KE is left in the round after passing through the Valentine's plate and into the fighting compartment, but it seems to do damag ewith about the same frequency as with the M2 HT. Not consistent, but about the same results in about the same amount of time.

[YankeeDog]

At least in regards to lePak vs. M2 HT, I think what is actually missing here is modeling of vital point targeting at close range.

Assuming a resonably experienced and trained crew, my guess is that at longer ranges (over 800m or so), the Pak crew aims at the center of mass of the HT to increase their chances of getting a hit, but at really close ranges where a hit is relatively easy to achieve(such as the 170m in the test), I suspect that IRL a lePak crew would aim for either the engine or the crew compartment to increase the chances of a KO.

This would slightly decrease the chance of a hit since the gun crew would no longer be aiming at center of mass (though at 170m it would probably still be very high), but it would also probably increase the chance of serious damage or crew casualty.

Not a huge deal to me, but perhaps a refinement that could be looked at for the future - I'm not sure the current model can handle this degree of refinement in hit and kill percentages.

Cheers,

YD