.50 / 20mm as AT

[jgdpzr]

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

Errr, Jason, you cannot have a round from a gun with a velocity greater than muzzle-velocity unless its rocket boosted.<hr></blockquote>

I think what Jason was saying was the muzzle velocity of the 25mm gun of the Bradley is much greater than the velocity of the rounds fired from the WWII 20mm or .50 caliber weapons.

I'll agree with you that Scipio's argument should really be a consideration of how the game differentiates between abandonments and knock-outs. This is really only relevent in operations.

[Blackhorse]

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

Blackhorse, you old salt, haven't seen you round these parts lately. The offer to buy you a few cold ones still stands, we'll have to look outside Okolona/Preston Hwy. to get a decent brew though...<hr></blockquote>

Hail Jgdpzr!

I'll take you up on that one of these days.

[Vergeltungswaffe]

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

Sure, that is terribly relevant. The Brad fires discarding sabot rounds with depleted uranium penetrators at several times the muzzle velocity. There is no comparion with WW II 12.7mm to 20mms, whatever. I'll tell you what, if penetration leads to kills 95% of the time, only when the (21 point cost) German 20mm Flak is firing discarding sabot rounds with uranium penetrators, I'll be satisfied. I'll even overlook the muzzle velocity difference, because I am so generous. Oh, that would still be never, wouldn't it?<hr></blockquote>

I never disagreed that CMBO has flaws in small caliber penetration dynamics, but if you want to argue relevance, fine. Splinty can tell us how prevalent DU rounds were for Brads, but you are sorely mistaken if you think they travel at several times the muzzle velocity of a .50cal or 20mm of WWII timeframe.

25mm muzzle velocity is roughly 1345 mps, with .50cal coming in at 850 mps, and 20mm FlaK at around 950 mps. We are talking about firing the latter two at a very poorly armored M18 Hellcat versus firing the former against a somewhat tougher target, the T-55 and/or -62. Regardless of somewhat greater kinetic energy, the 25mm round must defeat a vehicle with better internal stowage and more modern crew protection.

Thus, we are talking about roughly the same thing, proportionally, as Scipio's scenario. I will repeat, that I fully agree that the modelling needs work, and hopefully CMBB will have a better version. Anyway, enough about this. We will see how CMBB treats it, and your very valid points about bunker penetration.

[JonS]

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

1991 25mm vs T55 cf 1944 20mm vs Hellcat

...Thus, we are talking about roughly the same thing, proportionally, as Scipio's scenario...<hr></blockquote>

Well, you might be talking about the same thing, propotionately, but it would be a fluke. You have changed pretty much all of the parameters, by unknown ratios. So to say it amounts to the same thing is really, IMHO, saying way too much.

Regards

JonS

[ Edited for The Anglophile ]

[ 11-01-2001: Message edited by: JonS ]</p>

[Simon Fox]

Dear BTS,

I got three penetrating hits on a Tiger with a 17pdr, yes that's right THREE!, and nuffink happened. That's ridiculous! Your game is busted, pleaz fix or do somefink!.

P.S. Got the swine with No.4, though

P.P.S. Test? Whaddaya mean, test? Isn't general impressions and anecdotes good enough for you?

[Splinty]

Depleted Uranium penetrators for the M242 did not become available until after the Gulf war. We were using Tungsten penetrators for the APDS-T.

[Phantom Captain]

<blockquote>quote:</font><hr>Also in the game when you get "Internal Armor Flaking" results has anyone seen casualties caused from that? I'd expect that casualties from flaking armor should be as heavy as casualties from bounce-around-inside shots, but I don't think I've ever seen casualties from that cause myself <hr></blockquote>

i can remember two occasions when internal flaking has resulted in a casualty. both times it was only one casualty, and the tanks continued on. i believe they were shocked for a turn but that is all.

[karch]

I had a German HT abandoned tonight in a QB. There were some near misses by a Sherman and they just bolted. HT was listed as ABANDONED. I did a test some time ago to see what a mess of 8" arty would do against a field of tanks in a tight front to back/track to track grid. Lots of tanks abandoned without taking any hits at all.

I wonder if a lot of this is just a matter of symmantics (sp?). It seems that the game lists a vehicle as knocked out if it either blows up OR is abandoned immediately after taking a penetrating hit.

If not abandoned that moment, and the vehicle's crew leaves the next turn, regardless of taking any more damage, it's listed as Abandoned.

It seems theat people disagree that unless the tank is rendered completely inoperable by exploding or penetration by a really large chunk of metal, they want to know HOW the vehicle was knocked out physically. Maybe it isn't sometimes, and the crew did abandon it right after the penetration, but the game calculates that abandoning as knocked out instead of labeling it abandoned.

I don't care either way and don't have any stats to know if these guns did or could penetrate lightly armored vehicles. It just doesn't seem wrong to me as long as I realize it is a bit of abstraction, arbitrary naming and calculations.

regards,

Scott

[JasonC]

MV on German 20mm ran around 710 m/s. The round is also heavier for the 25. If you think 4 times the energy doesn't make a difference, then you should expect 50 cals to do what rifle bullets do. Because there is the same relationship between a Brad's round and a German WWII Flak round as between a Ma Deuce and a rifle bullet.

"But the target is tougher". We are talking about penetrating hits in either case; the penetration in not what is in dispute. It is whether penetration will lead to a kill, which is a function of the absolute energy of the smash. (Proof - shooting pistol rounds through a canvas or plank truck side doesn't cause "brew up"). The Brad gun is just a lousy argument.

Nobody has addressed the fact that planes in every way more vunerable than AFVs flew home with dozens of of these holes in them. Why do you suppose that is? Is it because everyone arguing the other side is primarily interested in realistic facts of real penetrations by small caliber WW II AP? Because surely, such an interest would mean even thinner skinned and more vunerable vehicles hit by the same rounds, are completely irrelevant to the question whether a penetration should nearly always KO the AFV, right?

[offtaskagain]

Other than fuel tanks in the wings, there is a pretty significant chunk of empty space in a bombers fuselage. Bullets aren't going to ricochet around the inside either. Also, I would bet most of those bombers with dozens of 7.92 and 20mm HE holes in them were scrapped if they managed to land safely, effectively KO'ing the machine even if the crew survives.

[Funker Vertinox]

Well depending if your tank crew is cowardly, fanatic, brave, or just ignorant of the battle situation should determine weather they will bail or not.

I'm sure there were a few tankers that kept on going even though they were missing a limb or two and others that jumped out of the tank as soon as threw a smoke grenade in front of them...

On a side note that I never really liked about battle front (or close combat for that matter) is that you couldn't get crew men to get back in abandoned vehicles that were almost in working condition.

Technically a panzerfaust could penetrate a tank and kill it's crew, but often would not toast the entire tank to a point where it was't beyond repair because of the concentration of the shaped charge.

I'm sure there were cases on the eastern front where the soviets just pulled the bodies out and put a few sand bags over the hole in that T-34 and kept going in the heat of battle

[Amedeo]

Don't know if this issue was already addressed but... does CMBO model the presence of an HE burster in AP rounds when calculating the post penetration damage? Moreover were the 20mm rounds we're talking about actually APHE-I rounds?

Regards,

Amedeo

[JasonC]

That empty space contains -bombs- on the way in. But if you don't like bombers, P-47s flew back with such holes in them too. And no, they didn't scrap every plane that had been hit afterward, they would have run out of planes if they had. The loss rate was only 1-2% per mission, and planes flew up to 100 missions. They patched them when they were merely damaged, which was often.

And there is rather a lot of empty space in an M3 halftrack that isn't carrying anything, more than in a bomber, but in CM they get KOed 95% of the time just like everything else. Face it - CM just used a simplified model of what happens after a penetration, meant for high caliber tank AP penetrating medium tanks. In other words, million Joule events. Any correspondance with realistic KO effect for small AP - 2 orders of magnitude less energetic events - is strictly coincidental.

Which is fine, it is of course the best WW II tactical game there is. But it does mean two things - 1. overuse of AA type weapons and other small AP for anti-tank (or anti-bunker) work is somewhat gamey as things are now (who would have guessed? To whom is it news?) and 2. BTS better pay attention to the issue before the Russian ATRs show up, or the 1941-42 Blitzkrieg of western Russia will ignominously succumb to 14.5mm AP. I'm sure they are on it.

[ 11-02-2001: Message edited by: JasonC ]</p>

[Red Dog]

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

That's the reason why the 3.7AA is such a deadly tankkiller, while it was in reality AFAIK never used as AT weapon. Possibly if nothing else was available, and I assume it wasn't very successfull.<hr></blockquote>

Actually, wasn't the 3.7cm AA gun also mounted on later models of the Stuka specifically for killing tanks... If it is indeed the same weapon, it was quite effective in this roll. Granted these would be hits through the much thinner top armor, but a penetrating hit is still a penetrating hit and it does show that the little 3.7cm could easily knock out tanks.

[PJungnitsch]

Here's a reply from Charles to a similar thread a year ago:

<blockquote>quote:</font><hr>The U.S. .50 cal was designed to destroy light armor. It can penetrate 12.7mm at 1000m, and 19mm at 550m, according to "Hell On Wheels" referencing the War Department's "Defense Against Mechanized Units". Obviously, at point-blank range, the penetration would be even greater (somewhere in the 22-25mm range, IIRC, sorry I don't have my data in front of me at the moment).

That's enough to defeat the Hetzer's 20mm side armor. And there's more...

The Hetzer has low quality armor.Very low quality. The kind that doesn't have the strength you'd expect. We rate it at 85% which is probably generous.

So the effective side armor basis of the Hetzer is 17mm, which the .50 cal can penetrate quite easily at short ranges.

And imagine what it's like. It's not a single shell penetrating. It's five, ten, maybe twenty or more. All richocheting around inside the tiny crew compartment, fragments flying everywhere. And more shots coming very quickly (no need to reload some big cannon, just squeeze the trigger!). The side of that Hetzer would look like Schweizer Käse.

The .50 cal is a big bad mama jama.

Charles<hr></blockquote>

Thought that might be interesting. And no, I don't think the plane analogy holds a lot of water either, planes have gotten severely riddled and still made it home, but they are completely different machines than light armoured ground vehicles.

[JasonC]

The 37mm is not a "little" gun. The Russian 37mm in particular has a muzzle energy of nearly 600,000 Joules, more than 10 times that of a German 20mm, and within half that of a 75mm AP.

Planes are different from light armor because they are more vunerable machines that fail catastrophically with the loss of fewer important subsystems. A HT with many holes in its side is a little breezy; a wing with many holes in its top is no longer a functioning wing. The wing also gets to double as the gas tank.

50 cals were indeed designed to destroy light vehicles - like airplanes. They also used 6 or 8 of them firing bursts from point blank to do it, because one hit was most certainly not enough. You had, indeed, to make something look like swiss cheese to destroy it.

A couple of hits out of an 8 round 20mm burst are not going to make a HT or light tank look like swiss cheese. If each hit only has a chance of causing a crew casualty, immobilization, or gun damage result, then piling up a dozen of them will indeed KO the AFV effectively, because it will accumulate such minor effects until the AFV can't be crewed, move, or fire. But one hit will not do this.

On the importance of hitting vunerable spots with small caliber AP, consider also the evidence presented by Russian ATR doctrine. They knew that only a hit at a vunerable point would cause significant damage. They used teamwork with molotov and SMG teams, with the ATRs trying to immobilize tanks, the SMGs preventing bailout, and the molotovs finishing them off. Hardly necessary if one 14.5mm hole KOs anything penetrated.

They did shoot for turret sides trying to kill crewmen, but the favorite target was the fuel tanks at the lower side hull toward the rear, the drive sprocket, the vision devices and weapons themselves. All imply that a crew casualty, gun damage, or especially an immobilization result, was what they were shooting for.

The juxtoposition is also priceless - these were anti-vehicle weapons, but planes are not relevant. Um, hello, planes are the vehicles they were designed to hit. The 50 cal is an AA MG. The 20mm is a Flak gun.

A Japanese "Oscar" fighter had 2 50 cals in the nose. With two "big bad muthas" chattering away, surely every P-47 - or even B-24 - an Oscar hit with a 2-second burst, was KOed, swiss cheese, all those shells and fragments rattling around inside. That is why the Oscar is known world-wide as a great upgunned WW II fighter, suffering no deficiency in main armament. Now, if only it had been maneuverable too...

[ 11-02-2001: Message edited by: JasonC ]</p>

[Andreas]

Some people here ought to go out and have a look under the hood of their cars - what would they find? Oh right, radiators, fuel pipes, distributor caps, yada yada. Now, if you go to a Sdkfz 251 HT, guess what you find under the hood. Full marks - radiators, fuel pipes, distributor caps, yada yada.

Now, a quick brush up on knowledge on what happens if a single .50cal round goes through your car's radiator/engine block/severs a fuel pipe (take your pick) - oh right, it won't run anymore. Surprise surprise. If you don't believe me, try it with your car at home.

Since we all agree that the round can penetrate the armour of the HT, and that said round can destroy generic vital parts of any vehicle, why is it so hard to comprehend that said round can do both with an HT?

Same goes for 20mm AA rounds going through lightly armoured parts of a TD. Unless you can show that there are no vital parts in the potential flight path of a penetrating round, you don't have a leg to stand on with your arguments.

All the ignorance of Jason in the matter of what can break in an engine or pretending that the round goes through the freight compartment, and not through the cab or the engine for sake of his argument about light guns, and all the shouting and huffing and puffing by Scipio won't change that and magically make it disappear.

Really.

[Redwolf]

I'd like to make the humble suggestion not to put more heat into this discussion until we actually collect some data about when CMBO does the following an penetration

- knockout

- abadonation

- crew casuality

- no effect

And that for regular and elite crews and for 20mm and 88 L/71. If regular crew mean "likely cowards" and they are modeld to abadon with the same chance that a squad changes from its ordered path, we discuss other issues as if hits on elite lead to the same effect.

There is the different issue of the flak guns that have a hit chance based on "one of four hits" but damage as "four of four hit", both for HE and AP.

[ 11-02-2001: Message edited by: redwolf ]</p>

[JasonC]

Germanboy, if the result of the burst were often an immobilization, I'd have what I want. Which others are arguing against, in favor of knock out. One bullet through the radiator will leak water until the engine overheats, then immobilize, minutes later. In CM, 95% of the time it not only immobilizes (instantly, of course), it also KOs the MG back in the fighting compartment. Call the Warren Commission about that "one bullet".

[PJungnitsch]

<blockquote>quote:</font><hr>Planes are different from light armor because they are more vunerable machines that fail catastrophically with the loss of fewer important subsystems<hr></blockquote>

Sigh... 1) Planes have a LOT of empty space inside. All planes. There's a reason why they are so much lighter for the same volume than a tank. 2) Most of what they are skinned with is aluminum or very light steel.

The result of this is that rounds will often punch through and not do any damage other than the hole. High explosive cannon shells are the best but even then wings and fuselage can all be terribly chewed up and the plane will still be flyable. Pilot armour was usually on the back of the seat and there are a few stories in which that got a pretty good hammering (shells passing through the fuselage) but the plane made it home. B-17's and Thunderbolts were famous for being able to come back after being chewed up all to hell.

Other differences are that planes are often multi-engined and have other redundant critical systems, fuel tanks are self sealing, plus it is much more of a committment to bail out of a plane than an AFV, so that more of an attempt will be made to nurse one home and then patch it up or scrap it.

AFV's on the other hand are made to be as small as possible (I'm always surprised how cramped tank interiors are). Rounds are not wanted inside at all but those that do will very likely damage something.

Again, the ability of a 50 cal or 20 mm to shoot down a plane does not have much to do IMO with how easily they can disable a Hetzer or Hellcat.

[ 11-02-2001: Message edited by: machineman ]</p>

[JasonC]

The armor around a pilot in a P-47 is quite similar to halftrack armor. Halftracks have at least as much empty space inside, because they are designed to carry things - the idea that all light armor has "no room inside" is thus quite wrong.

Another fellow reasonably suggested that we test to see the current behavior in CM. I did so, and there is a difference between light guns and the heaviest, but quite a modest one. I did not see any significant effect from crew quality, but if there is one, it would be more damage results from light cannons and fewer knock outs, going from regular to elite quality on the receiving end. However, the differences I did see might easily have just been random.

Here is what I did. I line up 10 regular King Tigers 350 meters in front of 10 regular M3 halftracks, facing straight at them, and fired until all the halftracks were dead, recording every hit as it occurred. I repeated until I had 100 hits. Then I used elite M3s and repeated, again until I had 100 hits. Next I replaced the King Tigers with Lynx and did the same test, 100 hits on each of regular and elite M3s once again. Here are the basic results I saw.

The 88L70 KO'ed the 7mm halftracks 91% of the time when they hit, only damaging them the other 9% of the time. Incidentally, 20-50% of the first shots missed, and occasionally an engagement took 3-4 shots and thus up to 45 seconds. 40% of the M3s burned, and I only saw 1 abandoned as opposed to KOed. This seems to be the primary result of a much more powerful gun - more brew ups and far fewer abandonments.

With the 20mm on the Lynx, only 75% of the hits KOed the halftrack. About 1/8 caused no significant damage and another 1/8 caused some sort of damage result - M-kill, -1 crew, gun damage, etc. The Lynx accuracy was higher, with only 1-2 occasional misses out of the first 10 salvos, and usually none (the hit prob read 94%).

And the engagements were faster - a shot every 8 seconds or so. As a result, even with the lower KO chance per hit, every M3 was dispatched within 30 seconds, and most by the time a King Tiger would have gotten off its 2nd round. Notice, 1/4 chance anything but KOed, try twice, leaves 1/16 un-KOed, vs. 1/11 only damaged by the Tigers, after a hit.

A higher portion of the M3s hit by the 20mm were merely abandoned, and fewer burned - 30% per hit were "abandoned", and only 7% burned. That was the main benefit of throwing millions of Joules at the targets instead of tens of thousands 8-16 times.

The benefits the Lynx gets from ROF modeling include - higher hit chance, each salvo still 75% likelihood to KO, 2 salvos in the time a larger gun gets off 1 shot, net chance of KOing rather than just damaging within 15 seconds was therefore higher with a 20mm than with an 88L70.

[manchildstein (ii)]

<blockquote>quote:</font><hr>Originally posted by Funker Vertinox:

I'm sure there were cases on the eastern front where the soviets just pulled the bodies out and put a few sand bags over the hole in that T-34 and kept going in the heat of battle <hr></blockquote>

if memory serves tanks were recycled. the u.s. 'hosed them out' first while the russians probably didn't bother.

andy

[LtData]

About all tanks can be taken out by small arms fire under certain conditions, and heavy MG or 20mm sure is not small arms calibre. They are quite powerfull actually.

If the tank is not buttoned up even a pistol shot in the right opening will do it.

Many tanks and armored vehicles had famous weak spots which made them vulnerable from small calibres at the right spot and angle.

[JasonC]

Lt Data - exposed crew can be hit by pistol shots, certainly. And if you have all day and receive no opposition, you can disable a tank with a wrench and a hammer. If standing near a group of friendly workmen, you might accomplish the feat with harsh language. What has any of them to do with KOing a tank? Produce one verifiable example of a combat report of a tank (the machine, not the crew; full tank, not a scout car) rendered inoperable by one pistol round. Sergeant Rock comics don't count. Or leave the fish stories to fishermen.

[Amedeo]

I have the impression that the current post penetration damage in CMBO is mainly based on the round calibre. I think that the main factors in a better model should be the actual resudual kinetik energy the round has after penetration and the presence and weight of an HE filler in the projectile.

BTW the Germans had both APHE and AP ammo for the 20mm, does someone know what they used in the late war years?

Regards,

Amedeo