.50 / 20mm as AT

[Andreas]

The way I understand it, a 'shot' by a 20mm AA gun, or a .50 is really a burst, with multiple rounds. So, if three 20mm AA rounds, or three-five .50 bullets penetrate, would you want to stay in the tank to wait for the next one? Discuss.

If three rounds penetrate, what are the odds one is hitting something vital in the tank? Discuss. Note, this could also be an abstraction for a non-penetrating hit on the turret ring, which leads to the tank becoming inoperable; this was a way how the German 37mm AT gun could deal with heavy tanks.

Gyrene, as to why the crews bail, I suggest you re-read Blackhorse's comment - he is a RL tanker.

[Blackhorse]

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

Redwolf, you have missed the point. The tank isn't abandoned - what could be explained with panic etc - the tank is KNOCKED OUT, so it's destroyed, finished, killed, kaput.

JasonC : thank you, that's excactly what I meant. And I totally agree, the damage caused by small arms with high fire rates is generally oversized.

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.

That's why tanks were equipped with BIG calibers, not with small fast firing guns. IMO, this is an very important issue. It is abolutly unrealistic, and in a very important aspect of the game.<hr></blockquote>

If the penetration value of a .50 cal is 30mm at 500 meters and a target's armour is 20mm, then the .50 cal rounds penetrate. If the .50 cal rounds penetrate, there is a high likelihood the vehicle will be knocked out. Why? because those slugs bouncing around inside the vehicle are going to cause damage. They are not cotton balls.

.50 cal and 20mm are only effective against non-armored and lightly armored vehicles, of which the Hellcat is one. They don't do squat against medium and heavy armor except to force them to button up.

[Scipio]

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

The way I understand it, a 'shot' by a 20mm AA gun, or a .50 is really a burst, with multiple rounds. So, if three 20mm AA rounds, or three-five .50 bullets penetrate, would you want to stay in the tank to wait for the next one? Discuss.<hr></blockquote>

The tank was - how often must I repeat? - KNOCKET OUT and not ABANDONED. READ AND THINK BEFORE YOU WRITE.

<blockquote>quote:</font><hr>If three rounds penetrate, what are the odds one is hitting something vital in the tank? Discuss.<hr></blockquote>

Have you ever used an automatic weapon? Shot one of a salvo will penetrate fine. Shot two not so perfect. And the more shots, the more inaccurate is the gun because of the recoil. So, what's the chance that all bullets penetrate? THINK!

<blockquote>quote:</font><hr> Note, this could also be an abstraction for a non-penetrating hit on the turret ring, which leads to the tank becoming inoperable; this was a way how the German 37mm AT gun could deal with heavy tanks.<hr></blockquote>

Why is a tank after a hit on the turret ring inoperable? A hit on the turret ring would result in a 'Gun damaged'. THINK.

<blockquote>quote:</font><hr> Gyrene, as to why the crews bail, I suggest you re-read Blackhorse's comment - he is a RL tanker.<hr></blockquote>

The crew has - once again - NOT abandoned the tank. The tank was KNOCKED OUT.

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

[Romeoman]

Actually, I've witnessed such light caliber knck-outs in CM much more often than I think it happened in RL.

Many accounts speak of multiple penetrations not resulting in knock-outs or even bail-outs. At Dien Bien Phu, the french Chafee platoon survived almost through the entire battle (less one tank, which brewed up early in the siege), although in the end, they had amassed many hits, mostly from 57 and 75 mm RR. They were immobilized on several instances, abandoned and recovered, during the same battle. It would be great to be able to have the crews recover their AFV once they no longer are suppressed.

Same goes for the japanese tanks at Nomonhan (aka Khalkhin Gol). They were hit several times by 45mm rounds fired by both BT tanks and AT guns, especially in the initial stages of the battle. However, despite penetrations, they remained in the battle until attacked by heavier russian tanks (T34 and KV1) later on. The penetrating AT fire would cause them to withdraw, but without abandoning the tank when at all possible, even if some of the crews were wounded or killed. This is another feature badly missing: panicked or out-of-control tanks, withdrawing or driving to the rear. AV's in CM are almost always knocked out by penetrating hits, even with very small penetration marginal. The resilience of AV's to such hits should be more akin to the way unarmored vehicles resist to HE fire... We've all seen trucks under fire from MG's 200 metres away and not abandoned directly (although 1 or 2 rounds in every salvo fired are bound to hit the truck).

The 20 mm gun carried by various AFV's in CM is the KwK38 with a clip of 8 rounds that can be fired automatically. Given the fact that the weapon always is turret mounted (thus very stable), I would expect these 8 rounds to be fired rather quickly, maybe in one burst, if the target is close enough... The same goes for the .50's, as they can fire at very high rates of fire if the target is close enough to ensure hits without prolongued aiming (unlike now when there always are those 5-6 secondes between bursts)...

[Tero]

Originally posted by Romeoman:

The penetrating AT fire would cause them to withdraw, but without abandoning the tank when at all possible, even if some of the crews were wounded or killed. This is another feature badly missing: panicked or out-of-control tanks, withdrawing or driving to the rear.

Agreed.

A Finnish KV-1 took several 85mm rounds in the face during the summer of 1944 fighting without any of them penetrating or doing any damage. The crew reversed into cover and bailed out after that. The story goes the crew stagered as if they were drunk. Their ears and noses also bleeded profusely. It took some time before they could climb back into the vehicle and continue fighting.

The resilience of AV's to such hits should be more akin to the way unarmored vehicles resist to HE fire... We've all seen trucks under fire from MG's 200 metres away and not abandoned directly (although 1 or 2 rounds in every salvo fired are bound to hit the truck).

Not exactly the same. A truck under fire will reverse out of harms way PDQ. The driver will rely on the speed of the vehicle to carry him into safety. OTOH a tank (even a sports tank like the M18 is sluggish compared to the truck and bailing out is often the only option for the crew to save itself.

Also, a non-penetrating HE round is almost worse (or at least as bad) as a non-penetrating AP round. Imagine the pure kinetic energy of a 105mm howitzer round slamming into the vehicle coupled with the energy of the exploding round. A friend of mine served in the field artillery and he told me that even a modern tank with reactive armour can not ignore field artillery fired at them directly.

The same goes for the .50's, as they can fire at very high rates of fire if the target is close enough to ensure hits without prolongued aiming (unlike now when there always are those 5-6 secondes between bursts)...

Except most 50cal mounts are not that stable mechanically (not as stable as the 20mm gun mounts) and thus their recoil would prevent any accurate sustained bursts.

[Michael Emrys]

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

When a round penetrates, it tends to affect the morale of the crew of an AFV quite severely. If casualties eventuate, they tend to remove their vehicle from the battle.<hr></blockquote>

This is a point that deserves repeating with emphasis. I don't know what the consensus of experience is here, but I see a lot of bailouts from still functioning vehicles when I think what happened historically was that if the vehicle would still run, the crew would pull back into a safer position. It might well be the case that for game purposes the crew would refuse for the rest of the game to voluntarily partake in any further combat, but for purposes of counting up the score, they should not be counted as destroyed.

Michael

[Redwolf]

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

The way I understand it, a 'shot' by a 20mm AA gun, or a .50 is really a burst, with multiple rounds. So, if three 20mm AA rounds, or three-five .50 bullets penetrate, would you want to stay in the tank to wait for the next one? Discuss.

If three rounds penetrate, what are the odds one is hitting something vital in the tank?

<hr></blockquote>

No that isn't what CMBO does. The hit chance of the multiple-fire is already raised greatly over a single-shot weapon. You get something like 75% for a multiple-fire AA weapon where a single-shot weapon has 40%.

However, that models that *one* of many rounds hits the tank. The chance of multiple rounds from the same burst hitting the tank would be much less than the 75%.

So, CMBO has to choose to use the multiple-fire model either for higher hit chance *or* for higher number of penetrating rounds, but not both at the same time.

[Herr Oberst]

Knocked out with no crew injuries sounds like a critical hit to something back in the engine compartment, or mechanicals that debilitated the tank.

This could be modeled simply as an "Ancillary system" NOT a fuel tank, NOT ammo, and NOT the gun.

Riddle me this: What would you do if your tank lost hydraulics and electrical?

Hmm, sit here in this big iron target? I don't think so.

[Scipio]

<blockquote>quote:</font><hr>Originally posted by Michael emrys:

It might well be the case that for game purposes the crew would refuse for the rest of the game to voluntarily partake in any further combat, but for purposes of counting up the score, they should not be counted as destroyed.

Michael<hr></blockquote>

I don't agree 100% here. If an abandoned tank is still operational - maybe after a repair - then they winner of the battle could in princip count all abandoned enemy tanks as captured. Captured enemy equipment was used in most armys.

Only - CM doesn't care about the strategic situation outside of the battle.

[Redwolf]

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

Redwolf, you have missed the point. The tank isn't abandoned - what could be explained with panic etc - the tank is KNOCKED OUT, so it's destroyed, finished, killed, kaput.<hr></blockquote>

I understood that, however your example is a single event. We need to discuss knockout chance and we can only do that only with a higher number of hits observed.

You see, your single knocked out tank could be the result of getting the shorter end of a 0.1% chance of knockout.

Or in other words, if CMBO had chosen a 0.1% chance of knockout on penetration, it is probably too low. If it has 90%, it is too high. From a single knockout we can draw no conclusions whatsoever on what CMBO uses.

<blockquote>quote:</font><hr>

JasonC : thank you, that's excactly what I meant. And I totally agree, the damage caused by small arms with high fire rates is generally oversized.

That's the reason why the 3.7AA is such a deadly tankkiller [...] <hr></blockquote>

No, it is so deadly because of the extremly high hit chance (which needs further discussion, IMHO).

<blockquote>quote:</font><hr>

That's why tanks were equipped with BIG calibers, not with small fast firing guns. IMO, this is an very important issue. It is abolutly unrealistic, and in a very important aspect of the game.<hr></blockquote>

No, real tank has big guns not to raise the knockout chance on penetration, but to raise the penetration chance as tanks went fatter (and the accuracy).

Scipio, I do not doubt that the knockout and abanonation chance in CMBO is too high, but we cannot discuss on single events when we deal with probabilities.

The first thing to investigate is how many knockouts, how many abanonations, how many non-abadon crew casualities and how many non-damage results you get from a penetration, and all this for the different experience levels of crews, and for different rounds penetrating.

I am not sure I want to run zillions of tests for what BTS has in their sourcecode as clearly stated numbers. Detective work is fine, but who are we to waste our time trying to find out something the programmer knows, the programmer whom's product we want to improve.

And without any historical evidence of what size of round penetration cause what damage the whole point is moot anyway. I have seen people stating that the smaller round penetration is in fact more dangerous to the crew and fragile parts inside the AFVs. Because the high-caliber round may go right through a tank, where the smaller one has a high higher chance of bounding inside the compartment, and the smaller round can ricochet more often (compare small and big rubber balls).

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

[Splinty]

A couple of notes on the .50 cal.I was mechanized infantry so I'm speaking from experience. First the AP round from a .50 will go through the engine block of a 2 1/2 truck,so imagine what it would do inside the turret of a TD or light tank. It wouldn't have to hit anyone,just lodge in the breech of the main gun or something equally as vital.One other note on the stability of the mount. We used the same mounts as they used back then and you'd be surprised how stable and smooth they were.

[JasonC]

A rifle bullet has a muzzle energy of 3000-4000 Joules. A 50 cal has 18,500. The Russian 14.5mm ATR has 33,500. 20-25mm guns have muzzle energies between 50k and 100k J, with 58k J for a common German type, for instance. In comparison, serious mid to late war tank AP guns have muzzle energies on the order of 1 million Joules. The 75L70 in the Panther and the 88L56 in the Tiger I both have energies of 2 million Joules. The idea that that whole range, above the rifle bullet, are going to do about the same thing if they manage to get through the armor, is ridiculous on its face.

By the time you've gone out to range, 1/3rd of the energy may be bled away. Going through the armor plate, especially if the overpenetration is only 5-10mm, is going to remove 2/3 to 9/10 of the remaining energy from the round, though some of it will be transfered to secondary fragments. Once inside, a 50 cal round will be between the energy of a pistol round (500J) and that of a rifle round (3500J), mean expectation maybe like a carbine round (1500J). That can cause a crew casualty, certainly. But if it doesn't, it is not going to destroy the tank.

B-17s and B-24s *flew home* with dozens of 20mm holes in them, and hundreds of 13mm-15mm holes. They are less protected than a Hellcat TD is. They took crew casualties, and some went down from fewer hits, to vital spots, but nothing like a majority. Their wings were full of av-gas, often their bellies were full of bombs, one hydraulic line or control surface hit in the wrong place can make them "depart controlled flight", as the saying goes. But a 20mm "penetration" did not mean "bail out" or "shot down". Heck, P-47s flew home with lots of holes in them too.

In my opinion, the wargame that got this subject most nearly right was Avalon Hill's "Tobruk". They have hit tables for aspect shot at that gave various locations of solid hits plus numbers of deflections. And then for each vehicle, the result of the hit varied with the weapon doing the hitting and where the vehicle was hit. You got C results from crewmen hit, M results for immobilization, K results for knock outs, etc. A Boys ATR might get a penetration but most of the time would cause a crew casualty, and sometimes immobilization (e.g. kill the driver). A few were bail outs (e.g. crewmen killed, rest panic).

On the subject of spalling in CM now, yes I have seen it result in a crew casualty and a "shocked" result. But it is rare. If you want to collect spall hits to see how common it is, you can reliably generate multiple spalls without vehicle KO by putting a Sherman 75mm up against 80mm flat armor - like a StuG, or Pz IV hull (the occasional turret hits will be KOs there, though) - at 1000-1200 yards.

[Andreas]

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

The tank was - how often must I repeat? - KNOCKET OUT and not ABANDONED. READ AND THINK BEFORE YOU WRITE.<hr></blockquote>

Scipio, you have to learn some manners. You are a prat with no clue, and you did not read my post. Any discussion with you is pointless, because you already know the answer. So why do you ask in the first place. Shouting and abusing people is the lowest form of discussion, and you do not deserve any reasoned answers from anyone.

Arschloch.

[MikeyD]

I once saw a film of a test where a metal weight was rocket-sledded into the side of a 105mm tank round to test its ability to withstand the shock... it didn't, and the resulting explosion was quite spectacular. That's why tank rounds were stored in individual armored cylinders in M60A1s and why they're stuck back in the turret bustle in the M1. ...and why extra armor was welded to Sherman hull sides right opposite the gun stowage racks. The danger of catastrophic cook-off is the prime danger for tanks.

[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...

OK, guys, sorry 'bout butting in here. Topically speaking, I agree with everybody(I'm easy)...the fast-firing AA guns seem to be a tad bit too effective, I think largely due to the abstraction of the multiple rounds being lumped into one. I think the crux of Scipio's issue here is that this should have been more accurately called an abandonment rather than a knock out. But I suppose it is not out of the realm of possibility that a few 20mm rounds bouncing around inside a vehicle could do enough damage to constitute a knock-out.

[Scipio]

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

So, if three 20mm AA rounds, or three-five .50 bullets penetrate, would you want to stay in the tank to wait for the next one? <hr></blockquote>

If the crew not want to stay in the tank, they bail. Have I understood this right? So what are talking about is 'Abandon', or am I wrong here?

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

Shouting and abusing people is the lowest form of discussion, and you do not deserve any reasoned answers from anyone.

Arschloch.<hr></blockquote>

GB, when I must repeat the same thing three or four times in a threat, I'm getting a bit tired.

I find it interesting that you, if you have no arguments, blame people that they

a)have generally no idea what they are talking about

b)are not able to discuss as adults. To call me an ashole was indeed an intelligent answer to my question.

I assume you read to much Schopenhauer: if you are going to loose a discussion, start to be personal insulting.

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

[Tero]

Originally posted by Splinty:

One other note on the stability of the mount. We used the same mounts as they used back then and you'd be surprised how stable and smooth they were.

I am sure the infantry ground tripod mount is stable. What kind of bursts did you fire: short or sustained ?

The majority of the 50cals in CM are vehicle mounted and of these vehicle mounts a vast majority are single point pintle mounts. Given the recoil keeping the aim true when firing at point targets with the purpose of taking it out I'd say the short, 3-5 round, burst would work better than sustained (8-10 rounds) bursts.

The 20mm FLAK mounts were more stable in this respect so a full clip of 8 rounds could be fired without the recoil foiling the aim too much.

[Michael Emrys]

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

I don't agree 100% here. If an abandoned tank is still operational - maybe after a repair - then they winner of the battle could in princip count all abandoned enemy tanks as captured. Captured enemy equipment was used in most armys.<hr></blockquote>

Ah, Scipio, you chastise people for not reading your posts, but here you are misreading mine. In the excerpt you were replying to, I was pointedly not referring to abandoned tanks, but tanks driven by their crews into safer ground whence they refrained from further combat.

Michael

[Scipio]

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

I understood that, however your example is a single event. We need to discuss knockout chance and we can only do that only with a higher number of hits observed.<hr></blockquote>

Sorry, this is a missunderstanding. Indeed I see this regular. I haven't run a test to count the chances, but it's surely not happened a single time or very rarly.

<blockquote>quote:</font><hr>No, it is so deadly because of the extremly high hit chance (which needs further discussion, IMHO).<hr></blockquote>

I guess the high hit chanced is cause by the high muzzel velocity combined with the high fire rate. Because : the muzzle velocity is one of the most important parameters CM uses to calculate the hit probability, and the more hits, the higher the chance for a penetration, and penetrations in CM means in 95% knocked out or abandoned.

<blockquote>quote:</font><hr>No, real tank has big guns not to raise the knockout chance on penetration, but to raise the penetration chance as tanks went fatter (and the accuracy).<hr></blockquote> Okay, but the result is the same.

<blockquote>quote:</font><hr>And without any historical evidence of what size of round penetration cause what damage the whole point is moot anyway.<hr></blockquote>

I agree. I'm desperatly seeking for sources and material about that. I find material like 'this tank has been penetarted several times'. But not if or how long he was operational after one or several penetrations.

[Scipio]

<blockquote>quote:</font><hr>Originally posted by Michael emrys:

Ah, Scipio, you chastise people for not reading your posts, but here you are misreading mine. In the excerpt you were replying to, I was pointedly not referring to abandoned tanks, but tanks driven by their crews into safer ground whence they refrained from further combat.

Michael<hr></blockquote>

Sorry, indeed I missunderstand you. Bad Scipio

[Redwolf]

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

I guess the high hit chanced is cause by the high muzzel velocity

combined with the high fire rate. Because : the muzzle velocity is one

of the most important parameters CM uses to calculate the hit

probability, and the more hits, the higher the chance for a

penetration, and penetrations in CM means in 95% knocked out or

abandoned.

<hr></blockquote>

No, the flak guns in CMBO have a higher hit chance that is not only projectile speed and rate of shots (bursts).

Look at the hit chance display in the LOS tool in the editor, the multiple-fire AA weapons have an enourmous hit chance, somewhat the probablity sum of 4 shots of a single-shot weapon, for a single CMBO shot (burst).

And the rate of fire (shots/bursts per minute) is high on top, that that is not the point and probably correct for AA weapons.

CMBO simulates that a single burst of 4 shells has 4 projectiles flying around and the hit chance displayed is the chance that one of those hits home. However when the result of the hit is computed, the single-out-of-four rounds hit is exactly as good as a full hit.

If CMBO had a correct abandon-on-penetration model, this needed to be corrected in advance, since it makes quite a difference whether 3 or 1 of those 4 objects penetrated.

Another problem is that the same applies for HE. I used the Bofors as anti-gun gun. Try it out. A HE value like four shells, but all hit home with the higher chance that one of them would hit home.

[Vergeltungswaffe]

According to some of the after action info I read from Trevor Dupuy, in Desert Storm there were several instances where the 25mm M242 Bushmaster was able to penetrate and BREW-UP T-55's from the side. So, regardless of CMBO's accuracy at modeling small caliber damage, it is certainly possible for small caliber rounds to f*** things up royally.

[Splinty]

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

According to some of the after action info I read from Trevor Dupuy, in Desert Storm there were several instances where the 25mm M242 Bushmaster was able to penetrate and BREW-UP T-55's from the side. So, regardless of CMBO's accuracy at modeling small caliber damage, it is certainly possible for small caliber rounds to f*** things up royally.<hr></blockquote>

I was there,on Bradleys and the 25mm APDS-T round did indeed knock out several T55 and T62 tanks.

[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?

[Ogadai]

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

What Scipio is quibbling about is basically semantics. In wartime, commanders don't care whether a tank has been "abandoned" or "knocked out" or "brewed up" until after the engagement is finished. In the midst of battle, a commander is concerned whether an AFV is a goer or not. If it isn't, its assumed its out of the running and will not be taking further part in events. How a tank is knocked out is immaterial to him, when he's considering his unit strength. As far as the crew is concerned, they're well aware of just how much of a deathtrap they inhabit. I was reading a post-strike analysis by Typhoon Fighter-Bombers in Normandy, yesterday and it was quite revealing. Despite many German tanks suffering only near misses or at worst minor damage, they were abandoned. Using your thinking, Scipio, they'd have been reoccupied and used, yet in real life they were abandoned and as far as the German commander was concerned, knocked out.

Instead of thinking like a gamer, think like a real tank crewman. I know if my tank was penetrated, I'd either withdraw (if it was still running) or bail out (if it wasn't). In cas you haven't heard, heroes tend to be in rather short supply, despite what Hollywood might have fed you.