BR350A and B HE fuse and Pzgn39 HE fuse

[T-34/85]

Sorry for posting this again, but i seen to not get much attention in the general threat

I was wondering how effective they are since theres a huge debate in Tripwire forums. (http://forums.tripwireinteractive.co...t=82009&page=8)

Unus Offa, Unus Nex claims that both US 75mm M3 and Soviet F34 rounds had a very unreliable fuses and did not work must of the time due to it being based of outdated shrinked navy HE charges. While also states that the small 18 gram HE charge of pure RDX of the Pzgn.39 would pierce a T-34 and cause a explosion and set it on fire 9/10. I personally find it hard to believe that the soviets and americans failed with the he fuse and did nothing about it.

Since I love this forum so much "wink" and I think you guys are are very well informed bunch, I would like to read what you have to say about this...

Resuming: 76.2 F34 firing BR350A or B with big HE burst of TNT with mixture- Very rarely effective due to being "outdated"

75mm KWK40 L/43 firing Pzgn39 with small 18 gram of pure RDX destroyes everything hehe.

That would mean CMBB isn't very well modeled in that subject aswell, now wouldn't it?

[JasonC]

I think pretty much all the folklore on HE bursters is utter nonsense. I sincerely doubt they make any appreciable difference for behind armor effect. The energy release packed into such small amounts of explosive is simply tiny, compared to the huge kinetic energies of the whole round and of the impact event. When a full AP round breaks through an armored plate and enters the tank interior, worrying about a little boost more is like firing a watergun in a hurricane. There is a reason modern penetrators don't give a lick about bursting charges. The round bursting through the tank wall is the smack that matters - it is a million to 10 million joule event, depending on the round we are talking about.

You might think it could make a difference with smaller rounds with a lower impact energy, but those can't carry any appreciable charge with them into the target. The rounds that might theoretically benefit the most are the larger caliber but slower velocity ones, which can carry the weight (caliber) but use the energy boost (lower kinetic energy from lower velocity). But even for those it is marginal. Most of the energy coming into the target is still the pure kinetic energy of the round, which all has to go somewhere. Receiving that energy is never fun and healthy for anything on the other end.

There was an observed difference in the likelihood of brew ups after penetration between many German tanks and typical Russian and early American models, but in my opinion it had everything to do with ammo stowage and nothing to do with what was coming through the tank wall or what firecrackers were set off afterward. Stowing the ammo low, away from the fighting compartment, separated in walled off silos, was distinctly safer. The US got the same benefits from later wet stowage. In comparison, ringing the turret with rounds is like wrapping the fighting compartment in fire starters.

I suspect that contemporaries saw empirical differences in brew up rates in the field, didn't know much about the actual mechanics, and ascribed it to the wrong cause. They made similar errors about fuel, imagining it had more to do with brew ups than it actually did, on the mere mental analogy between a fire and something meant to burn. The reality is tanks carry large amounts of highly dangerous powder within their ammunition and touching that off is the thing that leads to total kills, rather than the already substantial unpleasantness of flying metal perforating anything soft inside the tank. Whether a penetrating hit set off an ammo fire inside had everything to do with how the ammo was stored, with where the round specifically hit, and with the total energy dumped into the target. It can have had precious little to do with secondary fragmentation of the smallest splinters, it seems to me.

FWIW...

[John Kettler]

T34/85,

I have a great deal of respect for the depth and breadth of JasonC's knowledge, but I must disagree with him.

He's free to "sincerely doubt" all he wants, but combat experience from both sides in North Africa, and firing trials conducted by the 2nd Royal Tank Regiment at Beda Fomm tell a different tale. APHE which penetrates even halfway into the fighting compartment and detonates is devastating to the crew--ignoring ammunition storage issues and other matters later corrected.

Long piece of my post here

http://www.battlefront.com/community/showthread.php?t=105933&page=2

I quote myself in an excerpt from a much longer post lamentably lost in the Great Server Meltdown. The combat lethality of even the German 37mm AP shell was high if even a partial penetration of the fighting compartment could be achieved.

"It was not until 1942 did the British investigate the high incidence of fires in British tanks post penetration. Major G.B. Jarrett in May 1942: “The German projectiles which have caused the greatest amount of damage to allied tank in the western desert campaigns have been the A.P.-H.E. type in 47mm, 50mm, 75mm and 88mm respectively. These projectiles at long range need only attain a partial penetration and the explosive charge can complete the destruction of at least the tank crew. At closer ranges the destructive effect is very great, where in many cases destruction of the tank is permanent.”……….. Of those mark III and IV knocked out in combat by AP-shot, fewer than 20 percent were destroyed by fire or damaged so severely that they couldn’t be repaired."

--------------------------------------------------------------------------------------------------

Every now and then I get really lucky. Here is Jeff Duquette's detailed post to me with all the pertinent data. (Fair Use)

http://www.battlefront.com/community...ht=2pdr&page=4

Hey John K:

Some of what you maybe recalling might have been from your readings in Jentz. There is a reference by Jentz to G/B Jerratt (I have included it with the other scanned material below).

Best Regards

Jeff

From: Thomas Jentz “Tank Combat in North Africa, The Opening Rounds”. Schiffer Publishing Limited, 1998

From Page-44

4.1.1.1 BRITISH GUNS AGAINST AXIS TANKS

Directly after the battle of Beda Fomm, the 2nd R.T.R. conducted tests to determine the vulnerability of the Italian M. 13-40 tanks. They reported on 14 February 1941: During the morning tests were carried of the effect of the two types of 2-pounder ammunition on Italian M13 tanks. These tests proved that the yellow painted explosive armour piercing projectile penetrates the armour at 900 yards and bursts inside with very destructive effect. Sand bags placed on the crew's seats were well riddled with splinters. The black painted solid A.P. projectile also penetrates at 900 yards and causes large cracks in the armor.

From Pages 46-47

4.1.1.2 EFFECT AFTER PENETRATION

The destructive effect of the 2-pounder AP-Shot after penetration was based solely on whatever kinetic energy re¬mained in the solid shot, shot fragments if it shattered, and/or fragments of armor plate broken off by the hit. Starting with the design of the Pz.Kpfw.l, German designers had taken extra precautions to reduce the probability of fire as a result of penetration. Fuel tanks were separated from the crew com¬partment by a firewall (about 5 mm thick). In the case of the Pz.Kpfw.ll, the fuel tank, located on the right side of the crew i compartment, was isolated by 8 mm thick armor plate. As a further precaution, the main gun ammunition in the Pz.Kpfw.lll and IV was stowed in bins whose sides were 4 to 6 mm thick. In addition, main gun ammunition in the Pz.Kpfw.lll and IV was stored low in the hull. Thus, even when a 2-pounder AP-Shot managed to penetrate through the armor, it needed suf¬ficient residual kinetic energy to penetrate the firewall or am¬munition bins in order to destroy the tank by setting it on fire. Penetration of a Pz.Kpfw.lll or IV by 2-pounder AP-Shot fired at 600 to 1500 yards range frequently resulted in crew mem¬bers being wounded but infrequently resulted in destruction of the tank by causing irreparable damage or by setting it on fire. Of those Pz.Kpfw.lll and IV knocked out in combat by AP-Shot, fewer than 20 percent were destroyed by fire or damaged so severely that they couldn't be repaired.

====================================

Below is Jentz discussing German AP-HE projectiles – from pages 48-49.

====================================

As stated in a German report on armor-penetration curves: Basically all penetration data are valid for projectiles of good quality. The estimate of penetration for "worst" projectiles is possible only with great difficulty. The penetration can spread over a very large range below the given value. The regulations for acceptance of projectiles stipulate that a certain number of projectiles (1/2%) will be presented for inspection. Two-thirds of the projectiles which have been fired against armor plate, must satisfy the given conditions. Based on past experience, it can be stated that the largest part of the deliveries satisfy these conditions. 100% assurance is not given; it may always be expected that a small percentage do not achieve the specified penetrating ability, because of shattering prematurely. Also the explosive charge in these shattered projectiles will not detonate.

The effect of the projectile inside the tank and the probability of hitting the target are not considered in these graphical charts; thus only the complete penetration with the to¬tal effect inside the tank is considered. As a rule, this effect is of annihilating power when using armor-piercing shells with a high-explosive charge. When using hard core projec¬tiles, steel or soft iron core projectiles, or hollow-charge projectiles, completely annihilating effect cannot always be expected with a single shot, because the crew, located in the dead space of the tank, cannot be hit under certain conditions.

A limited effect, without piercing the tank by the projectile (effect produced by back-spalling of armor plate and punching holes (Stanzpfropfen) is frequently achieved with plates that are about 10% thicker than the thickness presented in the graphs.

AND from page 54

4.1.2.2 EFFECT AFTER PENETRATION

In all calibers of 3.7 cm and above, the normal armor-piercing round designed by the Germans contained a high explosive filler with a delay fuze. Penetration of a British tank by a German armor-piercing shell frequently resulted in crew members being wounded as well as destruction of the tank by causing irreparable damage or by setting it on fire. Not until 1942 did the British investigate the cause of fires in the tanks and began to install armored bins to protect the ammunition.

As recorded by Major G/B. Jarrett in May 1942: The German projectiles which have caused the greatest amount of damage to Allied tanks in the Western Desert campaigns have been the A. P. -H. E. type in 47 mm, 50 mm, 75 mm and 88 mm respectively. These projectiles at long ranges need only attain a partial penetration and the explosive charge can complete the destruction of at least the tank crew. At closer ranges the destructive effect is very great, where in many cases destruction of the tank is permanent.

When the 7.5 cm K.Gr.rot Pz. was fitted to an American casing and fired from the 75 mm M2 gun, in May 1942 Lt.Col. Gruver reported: Each German AP-HE round fired may safely be presumed to have put the tank out of action. In this con¬nection it was noted that the fuze functioned perfectly, that is to say it functioned only after penetration and then always in the fighting compartment where the most damage is done. Parts also frequently penetrated into the engine compartment.

The destructive effect of the Pzgr.40 after penetration was based solely on whatever kinetic energy remained in shot fragments when it shattered and/or fragments of armor plate broken off by the hit.

Jentz Refering to Italian AP-HE, page-57

4.1.3.2 EFFECT AFTER PENETRATION

The Italian 47 mm armor-piercing round contained a high explosive filler with a delay fuze. Penetration of a British tank by a 47 mm Italian armor piercing shell frequently resulted in crew members being wounded as well as destruction of the tank by causing irreparable damage or by setting it on fire.

__________________

End Post Excerpt

I went round and round with a whole bunch of people over this issue of APHE lethality over AP shot, and the Beda Fomm tests are conclusive, in my view, with regard to crew damage. The targets and other controllable parameters were identical, yet the results clearly showed that APHE trashed the sandbag crew simulators, whereas AP shot did not.

All the opinions and belief in the world can't reverse that fact, especially when the man who was decorated for saving the British butt at Gazala, by providing graze action fuzes for Grant HE shells lacking same and, more particularly, carefully extracting the 7.5cm PzGr 39 projectiles and machining down their driving bands on a lathe (on a spin armed shell) and fitting those to American cartridge cases, gave the Grant an effective tank killing round, says the same thing as the Beda Fomm tests showed. You have the quotes above. The story of the research is covered here on pages 23-33, with the decoration for Major Jarrett mentioned on page 31.

http://books.google.com/books?id=dJZ_3tBJUv4C&pg=PA24&lpg=PA24&dq=g.b.+jarrett,+ordnance&source=bl&ots=tXyePFqxVS&sig=pM6Kt0k3fEetkLQ1URUKs7UfcJk&hl=en#v=onepage&q=g.b.%20jarrett%2C%20ordnance&f=false

So, you now know, after reading the material at the link right above, the PzGr 39 was so good we converted it so we could use it. You also know the AP shell originally provided with the Grant lacked both a cap and a ballistic cap. It was AP, rather than APCBC--huge difference.

And here we have the BR350A, a strange duck of an AP shell if ever there was one.

http://208.84.116.223/forums/index.php?showtopic=31015

As you can see, it has no cap, but does have a ballistic cap, together with a remarkable appendage beneath that ballistic cap. In looking at the fuze, I can see what it would pop out during impact, for much of it is already out. Contrast that with the PzGr39, seen here in cutaway.

Note particularly the entire fuze body is inside the shell. Nothing's exposed except the base!

http://media.photobucket.com/image/pzgr39/sszza4/forums/88cmPzgr39-43.jpg

Hope this helps.

Regards,

John Kettler

[T-34/85]

Thanks both for the reply. I understand what JasonC is trying to say, Indeed HE charges compared in whats going on when the shell strikes the armor seems like shooting a watergun into a hurricane. But John Kettler does have a point with his sources, and its hard to ignore such facts. Thanks very much John Kettler for the massive information you gave me. Do you have deeper information in Pzgn39 after penetration effect in T-34 and BR-350A/B against Panzer IV after penetration? You will find lots of combat reports of german crews claiming that T-34s would catch on fire or explode most of time in the first or second penetration.

Thanks both once again for the replys.

[John Kettler]

T-34/85,

JasonC's view is correct provided the AP projectile actually significantly overmatches the armor. If it's AP shot, it can lose so much energy that it doesn't get through at all, and a partial penetration won't do much, as I've indicated. Whereas a partial penetration by AP shell can be disastrous, as seen in both the Beda Fomm tests and other evidences I cited, and in the Western Desert at the time, generally was.

From what I've seen, post penetration lethality of the PzGr 39 was more than adequate against the T-34, and the T-34/76 could certainly kill the Panzer IV, but JasonC knows far more than I do about the penetration performance of the Russian guns and ammunition. He's written at length on how the Russians got screwed in this area in CMBB. This, though, should help.

http://english.battlefield.ru/armor-penetration-curves.html

The T-34/76 in particular, even though diesel powered, suffered from very poor interior layout, which made it vulnerable to explosion following penetration.

This link will give you an idea of how the huge range advantage the T-34/76 enjoyed at the beginning of the war gradually shifted toward the Germans later on. It doesn't speak to terminal lethality, but it does give you some idea of what killing ranges were for targets engaged frontally.

http://english.battlefield.ru/t-34.html

In case the point made about the range was missed earlier, please see the combat range conclusions reached following Kursk here (third paragraph)

http://english.battlefield.ru/t-34-85.html

Here are Russian penetration figures, using different criteria than the Germans used.

Specifically included is the BR-350A. Please take note of Potapov's comment at the bottom of the second table regarding ammunition quality 1941-1943. He was a contributor to the data base for CMBB.

http://english.battlefield.ru/specification-and-armor-penetration.html

Hope the above help.

Regards,

John Kettler

[JasonC]

JK, your problem is that your sources don't say what you think they say, and there is no evidence they are right to begin with.

You see implications or evidence in them that simply is not there. I will illustrate from your own quotes -

Starting with the design of the Pz.Kpfw.l, German designers had taken extra precautions to reduce the probability of fire as a result of penetration.

Fuel tanks were separated from the crew com¬partment by a firewall (about 5 mm thick). In the case of the Pz.Kpfw.ll, the fuel tank, located on the

right side of the crew i compartment, was isolated by 8 mm thick armor plate. As a further precaution, the main gun ammunition in the Pz.Kpfw.lll

and IV was stowed in bins whose sides were 4 to 6 mm thick. In addition, main gun ammunition in the Pz.Kpfw.lll and IV was stored low in the hull.

(Notice, even at that point, he still talking about the fuel as though it matters. Hint, fuel isn't the issue).

Not until 1942 did the British investigate the cause of fires in the tanks and began to install armored bins to protect the ammunition.

(Notice, it's the ammo. You'd think the British would have learned this by the end of the battle of Jutland).

(Jentz isn't even talking about APHE or BAE, he is talking about standards on what counts a penetration to understand the figures in tables).

At closer ranges the destructive effect is very great, where in many cases destruction of the tank is permanent.

(And why pray tell would the range matter, if it is the magic firecracker on the back of the round that supposedly does?

Hint, because it is a higher impact velocity, more complete penetrations, more energy. The firecracker in the back doesn't cause "permanent"

destruction, but an ammo fire sure does. More complete penetration with lots of energy left, equals more chance of going right through rounds

inside the tank, which is what sets off ammo fires).

by causing irreparable damage or by setting it on fire.

(notice, nowhere is it alleged that this turns on whether the round has a firecracker in its tail. The most that is ever alleged on that score

is that crew wounding by fragments is more likely with APHE. But all the discussion of permanent kills instead talks about fire.

And we know what causes tank fires - it is setting off the tank's own ammo. And small fragments don't have any chance of doing that, if the

ammo is properly stowed and protected, as it was in German tanks from very early, and in Allied tanks only quite late).

[JasonC]

Do you know who actually knows about this stuff? Not colonels in 1942 flying by the seat of their pants. Try the Israelis after decades of detailed study -

Israeli statistics compiled after the 1982 invasion of Lebanon show that there is a 61 percent chance that a round striking a tank will penetrate; during the invasion of Lebanon only 41 percent of rounds striking the Merkava penetrated, Of rounds striking a tank, there is a 30 percent chance of penetration into the crew compartment; only 13 percent of all rounds striking a Merkava penetrated the crew compartments. This was due to the placement of the Merkava's engine up front and the thickness of the glacis armor belt. Normally, 31 percent of all hits set a tank on fire, and fire destroys the tank 85 to 90 percent of the time. Only 15 percent of all hits caused fires in Merkavas, and only one Merkava was lost to fire as far as is known.

The Merkava was designed with fully armored, self-sealing fuel tanks; fireproof containers that provide one hour minimum protection for all ammunition; and a heavily armored crew compartment. All crewmembers are required to wear protective asbestos clothing, and the tanks are equipped with an extremely fast-reacting fire suppression system built by Spectronix.

(Notice, not a word about firecrackers on shell tails, which nobody in the modern world uses for anything).

[JasonC]

Who else knows a bit about actually protecting tanks from total loss and tankers, too?

The folks who designed the M1. Did they give it firecrackers on the back of its shells to burn up the enemy tanks? No, they fire arrows of dense metal that carry tens of thousands of joules into the enemy tank on a thin axis. No firecracker attached (maybe a tracer to see where it goes).

But they did put all the ammo in bustles at the back of the turret, as far away from the front armor as possible, in action. They put them in 2 separate compartments with closing steel doors. They separate each round inside those compartments, with its own steel tube. They make the outside of the rear of these bustles flyaway items compared to the inside, if the door is closed, so if the ammo goes up, it explodes out the back of the tank, not into the fighting compartment. They keep ammo in the fighting compartment to a bare minimum, like 3 rounds.

Because they learned the lesson the Brits should have learned at Jutland, that armored beasties blow sky high and kill their entire crew if an armor piercing shell finds their magazine, especially if that magazine is poorly designed and not separated from the rest of said armored beastie.

[John Kettler]

JasonC,

Your ability to take a direct statement of fact and distort it beyond all recognition is simply extraordinary. What part of the conclusions from the direct comparison between 2-pdr shot and 2-pdr shell was unclear to you? This was an apples to apples comparison, with the only real difference being the projectiles. For the sake of the argument, let's ignore both fuel (which is an issue in that certain tanks, such as the T-34, didn't have engine compartments fully sealed off from the fighting compartment) and ammunition vulnerability issues. We're just looking at crew casualties. Quoting Jentz again from my post

"4.1.1.1 BRITISH GUNS AGAINST AXIS TANKS

Directly after the battle of Beda Fomm, the 2nd R.T.R. conducted tests to determine the vulnerability of the Italian M. 13-40 tanks. They reported on 14 February 1941: During the morning tests were carried of the effect of the two types of 2-pounder ammunition on Italian M13 tanks. These tests proved that the yellow painted explosive armour piercing projectile penetrates the armour at 900 yards and bursts inside with very destructive effect. Sand bags placed on the crew's seats were well riddled with splinters. The black painted solid A.P. projectile also penetrates at 900 yards and causes large cracks in the armor."

It says, to my best understanding of English, that the 2-pdr AP shell penetrated the Italian tank and, upon detonation inside the target tank, the splinters riddled the sandbags representing the crew. Signal by its absence is the lack of any similar result for the 2-pdr shot.

In case that was unclear, consider this

4.1.1.2 EFFECT AFTER PENETRATION

The destructive effect of the 2-pounder AP-Shot after penetration was based solely on whatever kinetic energy remained in the solid shot, shot fragments if it shattered, and/or fragments of armor plate broken off by the hit."

From that, follows this

"Penetration of a Pz.Kpfw.lll or IV by 2-pounder AP-Shot fired at 600 to 1500 yards range frequently resulted in crew members being wounded"

Now, contrast that with the riddling of ALL the sandbags when the 2-pdr HE shell exploded, as designed, in the fighting compartment of the M13 in the head-to-head Beda Fomm tests.

So, what you deride as a "firecracker" is surprisingly to you, unsurprisingly to me, devastating to the crew. From a debating standpoint, I'd argue you haven't legs left to stand upon!

You very carefully quote only those parts of the report which support you, while deflecting attention from the real issue, which is the lethality of even partially penetrating AP shell, which then detonates, to the crew.

Now, turning to various red herrings you've offered up, how is Israeli combat experience in Lebanon, with the super heavily protected and survivability engineered Merkava, relevant to the discussion at hand? Were the Merkavas hit even attacked by cannon fire?

Further confusing the isssue is that the design feature which gave the tank its name (Merkava, chariot, because the horses (engine) are in front) and has to be gotten through, together with its firewall, after the armored envelope is no longer in the way, drastically reduce the likelihood of any penetration of the crew compartment. So, the Israel design works in combat. Yawn.

As for the M1, recall first of all that U.S. firing tests in the mid 1980s, against an export model T-72, found that even our best 105mm round was tactically useless from the front. This led to the crash fielding of the 120 mm gun fired XM829 "Silver Bullet," which is profoundly different from WW II AP shot or shell. Not only is its roughly 40mm (2-pdr diameter) dart denser than even the tungsten which had preceded, it is pyrophoric! When it penetrates, it creates enormous showers of sparks. a huge and abrupt temperature rise, and highly energetic and dangerous flying particles from the long rod penetrator, not to mention being a toxic inhalation threat.

You also neglect to note the dramatic rise in muzzle velocities since WW II. That self same T-72 smoothbore 125mm gun fires its long rod penetrator at 1800 m/sec, versus 792 m/sec for the 2-pdr. As you know, the real driver in the KE equation is velocity squared, but the actual penetrator weight is also much higher for the Silver Bullet than its humble WW II predecessor. Thus, I think your basis for argument is codswallop, if that.

Frankly, I'm disappointed that, rather than exhibiting remarkable obduracy and intransigence in the face of hard fact you seem unable, for whatever reason, to accept, you didn't instead address the WW II terminal effectiveness issues for Russian ammunition that T-34/85 needs and with which you seem so familiar.

Regards,

John Kettler

[JasonC]

Quoting the same passage multiple times will not help your case, because those passages simply don't say what you think they are saying, one, and would not remotely settle the question even if they did, two.

In order then -

What part of the conclusions from the direct comparison between 2-pdr shot and 2-pdr shell was unclear to you?"

One, it isn't a conclusion. Two, it isn't a direct comparison of the ability of either to permanently knock out tanks. Three, it is the sketchiest sort of anecdotal report, not systematic evidence. Four, there is no sign those conducting it knew the main physical facts of the question.

"For the sake of the argument, let's ignore ammunition vulnerability issues"

Sorry, you just lost the point, right there.

"2nd R.T.R. conducted tests to determine the vulnerability of the Italian M. 13-40 tanks"

Notice, they think they are testing the vulnerability of Italian M13/40s to the British 2 pdr gun. They don't say they are testing the crucial role of firecrackers on the tail of shells.

"tests proved that the yellow painted explosive armour piercing projectile penetrates the armour at 900 yards and bursts inside with very destructive effect. Sand bags placed on the crew's seats were well riddled with splinters"

It doesn't say how many times they shot the tanks. It is entirely possible the answer is "once", which makes the test very far from systematic. It is also possible the answer is half a dozen times, in which case the information is very useful for knowing the round penetrates, but rather less useful at determining how likely one round is to wound the crew. It is likely that any AP shot penetrating the wall of the M13/40 could easily wound one or more of the crew. It may even be marginally more likely that APHE would lightly wound several rather than decapitate one. It is not obvious that this is more likely to result in an operational kill of the vehicle. And it there is certainly no evidence in a word of it, that the said round is more likely to permanently kill the tank by - wait for it - penetrating one of the tank's own shells and setting off an ammunition fire. Which is - wait for it - the leading cause of permanent tank kills, rather than minor damage and temporary abandonment.

"The black painted solid A.P. projectile also penetrates at 900 yards and causes large cracks in the armor."

Notice, the penetration performance reported is the same. Both reliably penetrate the thin armor of the M13/40. Bully. Your gloss is that the phrase "destructive effect" and shell splinters means the APHE KOed the tank. That round may have, if it was one round. Whoppee doo. It may also have lightly wounded 2 of the crew and left the tank functional after a period of daze and shock. We don't know. There wasn't any actual crew in it, and there isn't any sign there was actual ammo in it, either.

Next the AP causing large cracks in the armor, you gloss as less than destructive effect. You reason from the absence of a comment that the sandbags were untouched, but it doesn't actually say anything about the matter. It may be that the location the round struck the tank was simply different. It may also be the case that were ammo present, the AP round might have kept a higher KE through the tank interior and had a better chance of penetrating a tank round and setting it off. We don't know. It doesn't say. They weren't even trying to test such things.

They were trying to test how well the 2 pdr did against the M13/40 and they answered, "just fine, in penetrates easily with APHE or plain AP". The individual officer reporting the test may even have believed the APHE was more effective. He may have believed so because it is true, or despite the fact that it isn't. We have no evidence on the matter either way. All we know is that for one shot at least, he concluded that APHE could wound the crew with splinters. We knew that already. Bully.

"signal by its absence is the lack of any similar result for the 2-pdr shot."

No, that is your gloss, not in the statement. Moreover, for one shot it is meaningless anecdote, which could just come down to where the shots struck the vehicle. Nobody pretends that light AP penetrating a thin early war tank is a deterministic always the same process, without shot to shot variation. Again, you read in more because it supports a conclusion you already believe for other reasons. Your "conclusions" are not in the report.

"The destructive effect of the 2-pounder AP-Shot after penetration was based solely on whatever kinetic energy remained in the solid shot, shot fragments if it shattered, and/or fragments of armor plate broken off by the hit."

Well yes, and that is also true when a 120mm fin stabilized arrowhead 18 mm in diameter and 38 times as long traveling mach 2.5 dumps 12 to 13 million joules of kinetic energy into a tank interior. But strangely enough, the result is often the turret flying clean off after the ammo goes up, in such cases. Despite it all being remaining kinetic energy.

Now, the comment also makes it sound as though that kinetic energy is a small part of the affair - and your gloss is, compared to a firecracker. But in fact, the KE of a 2 pdr shot is 339,000 joules. A gram of TNT releases 4000 to 4500 joules when it detonates. The weight of bursting charge in small APHE is only around 2% of the projectile weight, which is 1.08 kg for the 2 lber. That works out to charge of around 22 grams and and energy release of 86000 to 97000 joues. The round itself has 3.5 to 4 times the energy of the bursting charge, in the supposedly so unimportant, mere kinetic energy.

And I very sincerely doubt the fellows out in the desert calculated any of that in making their comment.

Further, notice that beyond pointing out that the injury or damage mechanism of a solid shot is kinetic energy (which, guess what, we knew already), the comment does not manage to even allege that this is less than anything else. That is again a gloss on your part.

Your very next quote, moreover, points out that solid AP shot using only that very same kinetic energy "frequently resulted in crew members being wounded". Frequently, more than once, often. Notice, this is not remotely a claim that it took APHE to wound crewmembers. Since we just established that solid shot does what it does with KE alone (including of course all of the secondary projectile created by the shot entering the tank, rather violently), we cannot cite these passages as evidence that solid shot fails to wound tank crews because it "only" has KE to work with. It in fact proves the exact opposite, to a demonstration - that any penetrating hit, by shot or shell, frequently wounds crew members.

"contrast that with the riddling of ALL the sandbags when the 2-pdr HE shell exploded"

Contrast? Why? Is the reporter of the event making a contrast? Or are you? Sedond, he didn't say "all". It just said "were well riddled. We also don't actually know how severely, what with them being sandbags and all, not crew. Also, it was one event - unless the riddling was built up over multiple penetrations which would be an even weaker case.

The plain meaning of the report is that penetrations by 2 pdrs have BAE by wounding crew, and can do so whether they have firecrackers behind them or not. See "frequently" with solid AP and nothing but KE.

At the most, you may detect a spin that the reporter believes that APHE might improve the chances of wounding crew after penetrating. Without establishing that without the HE part the crew won't get wounded. And without - wait for it - even touching the more important question of whether either is going to permanently knock out the tank by starting an ammunition fire.

"what you deride as a "firecracker" is surprisingly to you, unsurprisingly to me, devastating to the crew"

I see frequent wounding either way, directly claimed. I see one shell wounding crew with splinters, I do not know how superficially. I call it a firecracker because it is only 20 grams, and has a quarter of the energy of the round itself.

And I think I have plenty of legs left at this point. We haven't even gotten to the actual issue in differential performance of tank killing experience in the field. You imagine that widespread use of APHE resulted in more full KOs with the shooter was German. Without much relating it to 20 grams and splinters wounding crew, I might add. I notice instead that (1) the Germans practice proper ammo stowage from the Panzer II on, that is, from the inception of their modern tanks (2) that the British did not even know that ammo caused the fires until OR revealed it to them in 1942, despite expensive prior experience on the subject in naval warfare, and plenty of opportunity to notice it in the field well before then. Both the Russians and the Americans also had poor ammo stowage practices well into midwar, which were not really corrected until wet stowage in the later Shermans.

I note in passing that the Beda Fomm tests predate actual British knowledge of what was causing full tank kills by 2 years. They were flat wrong about the matter at the time and for 2 years longer. They still thought fuel the problem in fires, for example. And it is entirely possible some also thought firecrackers on shell tails was the magic way to get brew ups, when post OR we know that to be poppycock. Whatever APHE may do for wounding the crew, it is ammo stowage issues and whether a round is physically struck with enough energy to pierce the shell casing and set off the powder inside, that causes ammo fires, which cause tank brew ups. Since the Brits didn't even know it was ammo fires that were the issue until 2 years later, citing their ignorance in the period when they did not yet know that is not very good for your case.

"the real issue, which is the lethality of even partially penetrating AP shell"

There is nothing in the items just cited that speaks to partial penetrations of any kind, they are all full penetrations. And they speak of frequently wounding the crew with plain AP. They do not say that APHE always causes crippling wounds to all the crew - there is no always about it, it is one single incident. And we don't even know how serious the wounds would have been in that single case.

But here is what we do know, not from an anecdote but from data. The average lost Allied tank resulted in at most 2 tanker casualties. For every total crew loss there was another full loss of the tank without injury to any of the crew. The normal thing was abandonment with 1-2 wounded. We know this because we have extremely accurate records of how many tankers were wounded, and less accurate but still excellent records of the tanks lost. And the enemy was using APHE all the time, right? So. It cannot be the case that every time APHE penetrated a tank it KOed the crew. There aren't enough dead and wounded crew for that to have happened.

"how is Israeli combat experience in Lebanon, with the super heavily protected and survivability engineered Merkava, relevant to the discussion at hand"

It is relevant because they have studied the matter of what makes a tank survive hits, and the crew survive even if the tank does not. The Merkava is a response to the earlier extensive experience of the Israelis in modern tank warfare, against much nastier weapons that 2 pdrs with firecrackers on the tail. The main lesson being to avoid ammo fires, ammo flash fires especially (hence the asbestos gear and fast fire suppression systems), and fast ones that brew up before the crew can get out (hence the design of separated ammo racks in which the ammo can even cooked off without burning through to more ammo, too rapidly i.e. before the crew can get out).

"the real driver in the KE equation is velocity squared, but the actual penetrator weight is also much higher"

Actually, the KE of the modern tank gun comes in at 12-13 million joules as I mentioned, while a Panther's comes in at 3 million (17 pdr similar). But the 88L71 and long Russian 122 are getting into the same weight class already, in pure KE terms. The big item beyond that is the narrow cross section of the round and a much greater depth behind that cross section, along with max density. The tungsten cores of WW II era APCR were about as dense as the modern rounds (most power used tungsten still). But the German APCR e.g. had a length about 4 times its diameter - for modern penetrators that figure comes in at more like 40 times.

Which is all about punching the smallest hole through the armor. That is the most efficient way to deliver KE to the interior of the tank. Much more efficient that trying to cart along a firecracker, I might add, which no modern tank armaments attempt to do...

[John Kettler]

JasonC,

Sadly, once again you signally failed to address T-34/85's request for assistance.

Turning now to your latest nonanswer, I note as follows:

The Beda Fomm tests pitted two different rounds, fired from the same gun type, at he same range, against an M13/40. It would appear that, since neither tank caught fire or exploded, that the vehicles weren't combat loaded. That the testers put filled sandbags on every crew seat tells me, as someone who did this kind of stuff very successfully for over 11 years and has a copy of what later became classified A-10 firing trials against a simulated, combat loaded, mannikin equipped Soviet tank company (engines running), that there was a real interest in looking at post penetration effects on crew from projectile penetration until the energy of whatever came through/was created was spent. The issue is neither ammunition stowage nor fuel, simply whether the round would penetrate (it did) and what happened to the crew as a result. I presented those results, which you promptly rejected. The APHE riddled the sandbags, but no such result was reported for the AP shot. What's so hard to understand? Yes, it penetrated the armor and cracked it , too, but there's absolutely no statement indicating it did diddly squat to the sandbags, as opposed to the APHE which "thoroughly riddled" them. It may not be obvious to you what the 2 RTR was testing at Beda Fomm, but it sure is to me.

I deliberately excluded ammunition and fuel from the discussion because I knew that your next rejoinder would be the British and Italians both had poor arrangements for both, thus biasing the test. Indeed, I find you have seized on what I didn't bring up in order to reject what I did! Meanwhile, you willfully ignore a plain statement supporting the lethality of APHE which detonated inside the fighting compartment.

"tests proved that the yellow painted explosive armour piercing projectile penetrates the armour at 900 yards and bursts inside with very destructive effect. Sand bags placed on the crew's seats were well riddled with splinters"

What part of "...and bursts inside with very destructive effect..." do you not get?

We now leave the realms of post combat lethality testing and enter the world of battle damage analysis. For the record, I have thoroughly read the classified JMEM on battle damage to tanks in the 1967 Arab-Israeli War. This, unlike your cited analyses on Merkava damage in Lebanon in 1982, is directly relevant in that it's absolutely certain tank cannon from both sides were used, as was WW II type ammunition. No long rod penetrators, no Chobham armor (or better), no DU! So, I know what I'm talking about when I talk about damage to tanks by various weapons. I've seen what HEAT does (clean hit) and doesn't (hit any number of brackets and flanges outside the tank, triggering it prematurely and saving the tank). I've seen what the Centurion's 20 pdr firing APDS could do, and I've seen the awful spall effects from HESH on a T-55's turret (pie dish sized hole clean through the radio from the inside rear wall of the turret).

From the German report Jentz cited

"As a rule, this effect is of annihilating power when using armor-piercing shells with a high-explosive charge. When using hard core projectiles, steel or soft iron core projectiles, or hollow-charge projectiles, completely annihilating effect cannot always be expected with a single shot, because the crew, located in the dead space of the tank, cannot be hit under certain conditions."

From the above, which is based solely on cases of complete penetration, it should be transparently clear that only APHE possesses "annihilating power," a characterization NOT given to AP shot!

Now, turning to the case of German HE vs. British tank

"Penetration of a British tank by a German armor-piercing shell frequently resulted in crew members being wounded as well as destruction of the tank by causing irreparable damage or by setting it on fire. Not until 1942 did the British investigate the cause of fires in the tanks and began to install armored bins to protect the ammunition."

Then we have

"As recorded by Major G/B. Jarrett in May 1942: The German projectiles which have caused the greatest amount of damage to Allied tanks in the Western Desert campaigns have been the A. P. -H. E. type in 47 mm, 50 mm, 75 mm and 88 mm respectively. These projectiles at long ranges need only attain a partial penetration and the explosive charge can complete the destruction of at least the tank crew. At closer ranges the destructive effect is very great, where in many cases destruction of the tank is permanent."

The above is both good news and bad news for you. It explicitly talks about the partial penetration scenario you hate and what that means, but then goes on to reinforce the direct KE impact part of your argument.

Now, we'll look at the conclusions drawn when firing the turned down 7.5cm PzGr 39 at the German tanks. These converted APHE shells are the principal reason Major Jarrett, who was our Ordnance liaison to the British and had full access to their combat reports, damage assessments and latest war trophies (the 88 he found and shipped home), was decorated by them.

"When the 7.5 cm K.Gr.rot Pz. was fitted to an American casing and fired from the 75 mm M2 gun, in May 1942 Lt.Col. Gruver reported: Each German AP-HE round fired may safely be presumed to have put the tank out of action. In this connection it was noted that the fuze functioned perfectly, that is to say it functioned only after penetration and then always in the fighting compartment where the most damage is done. Parts also frequently penetrated into the engine compartment."

Gruver neglected to qualify that statement with "which hits the tank and penetrates the fighting compartment's armor," but you get the idea.

Jentz also provides this

"The Italian 47 mm armor-piercing round contained a high explosive filler with a delay fuze. Penetration of a British tank by a 47 mm Italian armor piercing shell frequently resulted in crew members being wounded as well as destruction of the tank by causing irreparable damage or by setting it on fire."

So, over and over again the various data support the killing power of APHE, so what happens when the British fire the 2-pdr AP shot into the Panzer III and Panzer IV?

"Penetration of a Pz.Kpfw.lll or IV by 2-pounder AP-Shot fired at 600 to 1500 yards range frequently resulted in crew members being wounded but infrequently resulted in destruction of the tank by causing irreparable damage or by setting it on fire."

Contrast that with what APHE is consistently reported doing to the British tanks and crews!

The Aero Armor series book on the DAK showed a Panzer IV/D(?) in which two closely spaced 2-pdr shot had come through the driver's plate in line with his face and just above his head. The result? Driver had a head bandage and was still driving! Not exactly an instant kill, is it? In turn, this picture independently confirms combat analyses.

"Of those Pz.Kpfw.lll and IV knocked out in combat by AP-Shot, fewer than 20 percent were destroyed by fire or damaged so severely that they couldn't be repaired."

So, at that time, at least, Axis APHE was markedly more lethal against both British tanks and crews than was AP shot fired by the British against the Germans. It's also clear, from remarks from both sides, that when the Germans were able to recover their tanks, far more of theirs were fixable and could return to combat.

The Beda Fomm tests showed any reasonable observer that 2-pdr APHE was far more destructive to the crew and the tank than was 2-pdr AP shot. The other results cited indicate that adding ammunition and fuel to the equation only worsened the gap. Recall that Playfair completely reversed himself in the third volume of the HMSO official history of the war in the Mediterranean, concluding the German short 5cm gun was markedly superior to the 2-pdr. And the 5cm generally fired what round in armored warfare? PzGr 39. APHE!

Regards,

John Kettler

[ArgusEye]

John Kettler has taken the very defensible position of historical sources, and rightly so: he is correct. Whatever one may think of the tests performed during and before the war, they are the only ones providing real data that is not extrapolation on some modern assumption.

Any statements that those ignorant Brits were too stupid to see they were wrong, and trying to twist the resultant reports to fit a presupposition to this effect are just red herrings. As an aside, propellant became the leading cause of brew-ups only after calibers became larger, so their early worries about fuel tank protection being significant were quite well-placed.

The main reason that burster charges were used in '40s penetrators was not the 'howitzer principle' of the shot aiming to deliver a bomb into the target, but rather a desire to make the penetration, and any leftover kinetic energy, count. An AP projectile entering a tank would generate spalling, but this would contain only a very small fraction (2% seems typical) of the energy the projectile itself retained. This means that on the whole, the projectile would kill anything in its actual path very, very, extremely dead, but it would not harm anything it didn't actually hit, and stood a good chance of lodging or exiting, stopping its rampage. The burster charge was supposed to break up the projectile into a large collection of big splinters moving at the same speed, but in a quickly spreading cone, killing many things dead enough.

Now I must say that being in a tank with 60 grams of Hexogen exulting in fiery noise does not appeal to me at all, but it's unlikely to kill the tank on its own. It's not even likely to ignite cased ammunition. However, the crew will not be very alert for a while, and their fighting spirit is likely to be dampened quite a bit.

The burster is not necessary in modern long rod penetrators, because they usually disintegrate under stress anyway, and are -as JK already stated- often pyrophoric. Modern velocities and modern armour pose quite different demands than that of the 40's. Plasticizing long rods do not omit the burster charge because it was bad in the 40's, but because they don't need it and it wouldn't fit.

[John Kettler]

ArgusEye,

Thank you! I think, though, there may be another dynamic at work. How? If certain people acknowledge I'm right in the relatively straightforward world of military-technical-historical analysis, then they have to entertain the scary thought that maybe what I have to say on X-files, black ops and other deeply disturbing to them matters might also be correct. They simply can't have that, so won't yield an inch, as seen here.

If you take a look at the Ukraininan game thread, you'll see that the most cogent arguments I presented, solidly grounded in real data straight from the CIA and other intelligence agencies circa mid 1980s, from multi-day classified threat briefings I personally attended as a professional Soviet Threat Analyst at Rockwell and subsequently confirmed by both back channel sources not from the CIA, my own direct experience at Hughes Aircraft Company, Missile Systems Group (made the TOW) and by those very weapons showing up in the Russian arms export catalog (www.warfare.ru), have been either pooh poohed or ignored. People seem to be fundamentally unable to deal with unpleasant reality, but the truth is the truth. If they can't handle the brutal fact that 18 years (1980) after it was first fielded (1962), the U.S. Navy still had NO effective counter for the BACKFIRE delivered AS-4 KITCHEN antiship missile, then how can they deal with things and events which make that seem insignificant? That little AS-4 gem is from a classified course I attended called Naval Tactical Warfare Orientation Course for Industry, held at FLECOMBATTRACENPAC, a mouthful which translates as Fleet Combat Training Center Pacific in Monterey, California.

Turning now to your "60 grams of Hexogen" discussion, please bear in mind that the Crusaders and A10s of the time had NO armored ammo boxes, NO armored fuel tanks and DID NOT have fighting compartments fully sealed off from the engine compartment, which housed an engine which ran on gasoline! So anything of an APHE persuasion (37,47,50,75.88mm) which went Boom! inside (or even halfway inside, as seen above in the quotes), basically found the tank crew, ammo and fuel waiting to be hit and clobbered. There is a scathing book on British tank design, which unfortunately I have yet to read, called DESIGNED FOR DEATH. That pretty much sums up the situation, especially for the early war cruisers.

Regards,

John Kettler

[ArgusEye]

Being right on one point says nothing about being right on another. I try to judge all arguments on their own merits. Things that smell of conspiracy theories -I don't know if that is what you refer to- get extra scepticism, but outright dismissal due to a distrusted source is bad logic. If you are critical of military received wisdom, on the other hand, I cannot but agree. My brief forays into military ""science"" have left me rather disillusioned.

As for unarmored ammunition storage getting ignited: I must stress the difference between cased and uncased ammunition and -more importantly- propellant. I also make a big distinction between the action of the charge and its secondary effect of fragmenting the projectile.

First: to ignite the propellant in a cased round one needs either shock or temperature to exceed the limits for either the enclosed propellant or the squib that is meant to start it off [the primer]. The former is encased in brass, which needs quite some pressure to deform, and therefore protects the propellant quite well against shock waves. I haven't quantified what would be necessary for the shell to deform significantly, but I think you will agree that for the crew, pressures sufficient to deform a casing will be lethal enough to think ammo cook-off a distinctly unimportant issue. The primer is usually exposed (except in some electrically-fired rounds), but needs significant temperatures and pressures as well. This can be achieved by the burster charge if it detonates very close by, but is not too likely. The warhead, I think you will agree, has an even higher resistance to sympathetic ignition.

However, if the propellant is bagged or in open casings, then the story becomes quite different. Shockwaves are still very iffy, but heat from the flash of detonation can set off such charges if they are not shielded. Unfortunately [depending on which side of the armour you are] the shielding is done in large part by the projectile body itself, which contains much of the heat of the initial detonation.

If we take into account how the burster charge bursts the projectile into multi-gramme chunks of jagged hard steel, moving faster than a rifle bullet, then one can easily see that one of these piercing a cartridge would set off the propellant, even by shock alone. If the propellant is of sufficient quantity to heat the round next to it to its propellants flash-point, then we obtain a chain reaction which will quickly consume the tank.

My understatement in my earlier post was meant to be facetious. Sixty grammes of hexogen gives an overpressure in an enclosed space that is likely to kill, and certain to stun.

As for the original question: I apologize for not responding earlier, but I needed to look some stuff up.

The BR-350 family and the BR365 were based on joint Soviet-German ammunition development in the early 30's. The Germans then made one step further after they found that their Pz Gr rot. did not function to specification against armoured targets. According to the Gercke papers, the Pz Gr rot turned out to fuze unreliably and if it did, would be fine against crew but not too effective against machine parts. The former due to the fuze, but the latter due to the burster charge pulverizing the projectile too finely. The new family of PzGr 39 projectiles, in use throughout the war, had a smaller burster charge which was more likely to kill machine parts, rip fuel tanks, spill over into more of the fighting compartment, and to ignite ammunition stores.

The new fuze was designed after significant amounts of research on the origins of the failings. The research led the Germans in the opposite direction of Allied conclusions. The Germans miniaturized their detonators' mechanical parts, where the Allies tried sizing them up to make them more robust. Robustness was not the problem, however; the problem was ductile seizing of the mechanism under shear loads. In fact the Russians and the Germans used very similar mechanisms, but the Germans had gone one step further in basic research.

As for the Americans, I have yet to look up their fuse designs and development, but that seems a fine job for somebody else until I can find time.

The T34 was quite likely to blow up, but 90% seems quite excessive. I have no hard figures, but I found a Brit reference [rather, someone referencing a Brit reference] that it took 2.5 penetrations on average to brew up a T34. I have no clue how seriously that should be taken though.

The reason for the T34's vulnerability seems to lie less with German projectiles and more with its safety engineering. Where the PzIII was basically a bunch of escape hatches on tracks, the safety philosophy behind the T34 could be summarized as 'go die for the Rodina, comrade'. Very little thought of crew survivability on penetration is evident in the design.

[John Kettler]

ArgusEye,

Are you the offspring of rexford, Jeff Duquette and Valera Potapov combined? Color me blown away by your in-depth knowledge! As a general rule, antitank ammunition of the period was fixed, leaving no exposed propellant bags. The exceptions I know of would be SU-122/SU-152/ISU-122/ISU-152/IS-1,IS-2 on the Russian side and the Jagdtiger on the German side, together with some odd ducks which weren't mass produced.

Your library and files must be incredible, in that you seem to be totally at home with the intricacies of APHE fuzing, joint Russian-German ammunition development, of which I knew nothing, design papers I've never heard of, and more.

I totally missed the facetious aspect of your reply, but maybe that was because of a dreary diet of "firecracker in the tail" cracks before you appeared. I think to some degree I fell into the Mark Twain "The River Pilot" trap and began to doubt my own knowing. This was worsened by having no real sense of fragment velocity (too wrapped up in the debate to even check), but I see that my innate sense of what was happening at detonation was, in fact, correct--hell in a very small place (thank you, Bernard Fall)!

Regards,

John Kettler

P.S.

Looked up the detonation velocity for Hexogen/RDX--8750 m/sec!

http://en.wikipedia.org/wiki/RDX

A gunpowder firecracker is a whole 1350m/sec by contrast (Table II, p. 365).

[PDF]

War and Energy

www.vaclavsmil.com/wp.../smil-article-2004-war-and-energy.pdf

[ArgusEye]

I'm nowhere near as informed as the people you mention. I'm just a physics researcher being bored in the university library, and my next project doesn't start until we can find funding. My knowledge is by no means broad, but I have a slew of technical books, journals and papers around, so a few days of rifling through yellowing papers yields the above.

The Gercke papers should be well known. The Brits made comprehensive commented translations.

In the thirties Germany was still more or less adhering to the Versailles treaty, and they were not allowed to do any weapons research that might be remotely modern. Tank warfare and submarine warfare were therefore studied in joint projects with the Soviets. Of course, neither the Soviets nor the Germans were entirely forthcoming in providing their full know-how, but some similarities in ammunition production can be seen. The main effort seems to have been by Krupp. I have not found anything substantial from other arms manufacturers, but I didn't spend time looking. In submarines, the similarities were much more palpable.

Detonation velocity is not all that relevant in this discussion. Not only because the velocity drops significantly due to the plasticizer added, but also because it isn't a big factor in fragment velocity. Hot gas volume generation is what counts there.

[John Kettler]

ArgusEye,

Whatever the cause of your boredom, I'm grateful for the means you chose to combat it. I had never heard of Gercke, but then, I'm nothing like the ammunition grog you are. Shall have to look into them. I'm broadly familiar with German-Russian shared design projects, but simply hadn't crossed paths with the ammunition side of the effort.Would welcome a discussion of the hot gas volume generation issue. I'm familiar with the usual artillery shell and bomb burst situations, where the item balloons before the case disintegrates into a cloud of variously sized fragments, but am pretty sure I've never seen any high speed imagery of APHE detonation. With the burster charge in the base and the case walls much thicker than for standard HE, I'd imagine the phenomenology would be somewhat different.

Regards,

John Kettler

[c3k]

Re: the KE of the 2 lber as stated by JasonC.

If the KE is on the order of 400,000J, and the burster charge has an energy of roughly 100,000J, we are MISSING a comparison.

What is the POST-PENETRATION KE of the projectile? The amor, before failure, ABSORBS some KE. (Note the many reports of dents and glowing armor from non-penetrating hits. It takes energy to deform and heat the metal.)

So, if the KE which is transferred into the fighting compartment is LESS than the KE which is delivered to outer surface of the armor, the relative power of the burster charge becomes more important.

How much is the KE reduced by penetration?

[JasonC]

c3k - it is a fair question but with a proviso. All of the KE goes into the target. Some as heat, some as kinetic energy of portions of the metal, some remaining as KE in the original round. There is no requirement that the energy remain in the last of those forms to be effective inside the tank. All of the KE (including that of shrapnel from the penetration, any secondary spalling, etc) and even the portion of the heat carried by the original round and by such shrapnel from the penetration event, is potentially damaging to the vehicle interior. In any of those forms it can potentially penetrate shell casings in the vehicle walls or floor and the interior. There is vastly more potential energy in the vehicle's own ammunition stores, especially as propellant for its own rounds, than in either the original round or any charge it carries.

Remember the KE of the round came from somewhere, itself - from a chemical reaction of the propellant that threw it across the intervening space between the two vehicles. That same potential energy is lying around inside the target, multiplied by the number of rounds it carries (tweaked at the margin, to be sure, by any differences in its round energy and that of the shooter hitting it). The critical question is whether any of the energy dumped into the vehicle interior by any process, sets off any of that propellant, or fails to do so. If it does, absent specific and difficult round separation practices and marginal events, all of that potential energy is going to be released, in an ammo fire.

Charge on the 2 pdr tail - 86,000 joules of energy. Charge used the throw the 2 pdr shell, translated into its KE - 4 times as much, even after mechanical losses in the conversion (escaped gases at the barrel bore, etc). Charges lying around inside a tank that carries 50 to 75 such rounds - 200 to 300 times the energy of the charge on one round's tail, divided by the physical efficiency of the shot process.

That is the underlying physical point behind my emphasis on ammo fires as the critical issue. The overwhelming majority of the potentially damaging energy present, is propellant of the targeted tank. And the majority of the energy that might set that off, is coming from the propellant used to throw the round at said target, hard enough to bust inside it. The projectile is a mere delivery mechanism. At bottom, the propellant in one tank is trying to set off the propellant in the other.

[c3k]

I agree that the propellent in the ammo is the primary means of destroying a vehicle. (And I like your final sentence...that needs to be up on a wall in various armor schools somewhere.)

If the ammo cooks off (talking strictly WWII tanks!), the men inside will die.

However, another method of taking out the tanks exist, and that is wounding the crew.

The loss of KE due to penetration is significant, unless the armor is overmatched by orders of magnitude. Examples: 88L70 vs. Stuart; US Abrams vs. well, a lot. In other matchups, say a 75L48 vs. Sherman frontal armor, the loss of energy is significant. In that case, the burster charge makes a difference.

That burster charge creates large chunks of hot metal traveling at significant velocities inside the tank. Yes, the PENETRATION also produced chunks of hot metal traveling at significant velocities. More chunks of hot metal flying around the inside is better at achieving the goal of killing the crew or cooking off ammo.

More is better.

If the KE which is delivered to the target tank is changed to heat the armor, that is worthless for killing the tank. Any energy which deforms the armor is worthless. A dented tank can still fight. Any energy which is used to transfer momentum to the target tank is worthless. What matters, as you've alluded to, is the energy dumped inside the fighting compartment. Then, once that energy is delivered INSIDE the tank, what it does in there is critical.

My question still stands: how much energy is used in penetrating the armor?

(Rexford would know. RIP.)

Thanks,

Ken

[c3k]

I've found some data, here: http://www.tarrif.net/cgi/production/all_penetration_adv.php

I have NO idea about its validity.

That website gives 2 pdr (40mm) as having 2 ammo types, the solid AP is lighter, at 1.08kg, and the AP HE is heavier at 1.18kg. (That seems backwards to me, but I do not have other data available, so I will use it as it exists.)

The first penetration range on the table is 100m. For the sake of simplicity, we'll say the first 100m of flight takes place in a vacuum. Against RHA at 30 degrees, the lighter shell penetrates 66mm. The heavier goes through 64mm. (There may be some design issues with shell hardness/shape. Shrug, I'm taking it as it is presented.) Both have MV's of 808 m/s.

KE = 1/2mv^2

1/2*1.08*808*808 = 352,546.56 kg m^2/s^2 or, roughly 350kJ.

(I used the lighter round to purposely understate the ability of the armor to absorb KE. If we use the 1.18kg round, the KE is 385kJ, very close to, if not the same as, the number JasonC quoted. If 66mm of armor aborbs 385kJ, then that gives a rule of thumb of 5 or 6 kJ per mm. Yeah, that's nothing I'd quote. The real armor effects are far more complex.)

So, 350kJ can penetrate 66mm of RHA at 30 degrees. (Given the LARGE assumptions I've pointed out, above.)

Going extremely far out on a limb, we can state that the PzIII's 30mm of armor would take 1/2 of the KE from the penetrator. (Angles, assuming RHA, etc. all tossed out of the way for ease of this back-of-the-envelope calculation.)

That puts about 175kJ into the fighting compartment... That makes the 80kJ burster look even better. Round numbers, that HE filler adds an additional 50% of behind armor effects to the penetration.

Oh, that is at muzzle velocity. The benefit of the filler only gets better as the velocity, hence KE, drops off with range.

That same table gives 1,000m penetration as 35mm. At that point, the round barely gets through the PzIII's 30mm of armor. The KE is approaching 0. The 80kJ of the burster charge is 100% of the behind armor effects.

I disagree that HE filler is worthless for igniting ammunition.

All the above is quite rough, but the numbers point out the trend and are within an order of magnitude, at least, of the effects.

Ken

(One last cocktail nampkin comment: that 80,000kJ added by the burster is the same amount of energy as a 500 pound engine block moving at 60mph. I would not shrug off a hit by a engine block at that speed. It is a significant amount of energy for a human to be exposed to. It may not blow the turret off a tank, but it has a good chance in a closet-sized space, of hitting ammo or hurting a human.)

[Bigduke6]

Great thread guys.

Here's a couple of some questions I bet you can answer, that might (or might not) add to the conversation. Both are from the Red Army and have to do with the IS-2 tank.

Anecdote 1: Once the IS-2 got sent into combat and tanks started getting killed, Soviet technicians noticed something peculiar: a certain percentage of the "killed" Stalins were to all intents and purposes functional, hull intact, turret in place, ammunition in bins, and in a couple of cases with all systems functioning and even the engine running. But the crew was dead inside and a single German AP penetration was found to be the cause. There weren't any numbers of cases like this so I can't offer any thing on which to build statistics. This was rather presented as evidence of the solidity of the Stalin tank - even when the crew inside gets killed, sometimes the tank itself isn't hurt. It was not presented as just a weird battlefield incident, but rather something that happened that was evidence supporting a conclusion, in this case that the Stalin's size and armor was substantial vs. German ammunition of the day.

OK, so question one is: You have a Stalin, there are two guys in the turret and two in the forward hull, there is a single AP penetration. I think it's safe to assume the penetrating round was an L70 75mm or some variety of 88mm. What could happen after that penetration that would kill the entire crew, yet leave the tank itself essentially intact? Let's not forget IS-2 ammo was not unitary, i.e., it came not in one piece but two. Any one want to speculate on how that happened?

Anecdote2: This one is better-researched. IS-2 as most reading this probably know were fielded in heavy tank regiments and used primarily as part of a major attack at whatever level of Soviet command was trying, and secondarily to make German armored breakthroughs painful. In general IS-2 was not, by the Soviets, considered an anti-tank weapon, however, because of the separate and independent nature of the Stalin regiments, and a higher level of education among Stalin crew, there is a moderate to tolerable amount of memoires and available battle reports on how IS-2 did when it did wind up shooting at German armored vehicles.

There are lots of conclusions which have actually been beaten to death in other threads years ago, but this thread made me wonder about one of them. It seems like it was a general assumption, both by commanders throwing IS-2 regiments into combat, and by the crewmembers themselves, that the 122mm gun was powerful enough to defeat the armor of almost any vehicle in the German inventory, but, from most certainly not Tiger II from the frontal aspect, and possible a few of the heavy assault guns.

But, and this is where my question comes from, even in those (really not so common) cases where the 122mm AP was deemed insufficient to overcome the German armor, it was considered a viable tactic to fire HE. The idea was the blast on the outside of the German tank would be sufficient to break it somehow. For the same reason, 122mm HE rounds were considered a possible munition for use against lighter German tanks.

I can't prove that these anecdotes are the same as reality, but I can say the idea that "122mm HE really is enough to do a number on any German armored vehicle, but not always" seems to have been a common assumption in the Soviet memoires and battle accounts I've read.

So, assuming that no one was lying, here's several questions for you smart guys: How could it be that a 122mm HE round could, without penetration, cause substantial damage even to a medium German tank, never mind a Tiger? The velocity of both the HE and the AP rounds appears to have been 800 meters a second. The HE shell appears to have weight 25 kg and the bursting charge 3.6 kg.

Is that velocity plus weight plus bursting charge enough, reasonably, to cause substantial damage to a German medium tank? To a German heavy tank? If it's an HE round, is KE even a factor?

Thanks ahead of time.

[Erwin]

We've talked a lot on CM2 forums about how tanks become useless if all the exterior equipment that can be damaged is damaged - periscopes, view slots, gun damage, perhaps even thermobaric FX?

[ArgusEye]

I'm intrigued by the IS2's standing around intact with a single penetration and a dead crew. It doesn't ring a bell about any particular weapon. If the burster charge were the reason, there should be splinters and chunks all about the place. The only thing that springs to mind (and is obviously NOT applicable) is a stern warning to German tankers not to use captured Soviet petrol heaters due to monoxide poisoning cases killing all guys in a tank. Unless they started to fire these stoves at high velocity, I don't think we should assume this to be the cause.

As to the use of 122 HE against tanks, this is quite obvious. Even though the HE round was too soft to actually penetrate, it gives a huge impact to the armour, and especially late war when the German armour quality dropped, this would cause spalling and broken seams. You can call it unintentional HESH if you will.

Also bear in mind that by late war, the Pz IV was still around in great numbers, and it was no longer the reliable workhorse it was in the early years. The upgunning and expediences of industry had turned it into an overloaded deathtrap constantly hovering on the edge of breaking down. A good near miss from a large round could tip, break, or seize up plenty of overstressed components.

[JasonC]

The energy of a German 75L70 round was about 3 million joules. For the 88L71 it was more like 5 million joules. The Russian 122mm has a muzzle energy of 8 million joules. Compare modern hypervelocity smoothbores, which has 10 to 12 million joule energies. All of these are very high figures. The German rounds pack that energy behind a narrower cross section, getting more of their energy from velocity and less from mass, which helps penetration for the same reason modern arrow rounds do better than all older, full diameter penetrators. But everything in this weight class - late war best tank guns on both sides - is within a modest factor of modern main gun energies, and dwarf the energy of earlier, midwar guns.

When a 3-5 million joule round penetrates the armor, the effects inside are not fun. Besides lots of chances to set off the tank's own ammunition, and spalling, there is also just overpressure when the tank wall "gives".

The point of entry of the round into the tank is an explosion, nothing less. In a small fraction of a second, a steel wall several inches thick and across is basically vaporized. The round and the volume of metal it displaces from the wall are comparable in mass, and the round was traveling twice the speed of sound before it hit. If the plug coming out remained intact you'd be playing billiards with 2 cannonballs after the collision each going about the speed of sound and weighing tens of pounds. Normally it doesn't, and instead the armor wall is sprayed into the interior in fragments and shards. But just like any explosion, you also get an overpressure wave into the tank interior.

It is entirely possible the IS cases you mention are times when that shockwave or those fragments killed the crew outright - and there will be others in which the same happened to half the crew but not to the other half (in the turret compartment only, or in the front hull compartment only). It is also possible they died in flash fires of exposed propellant that did not do appreciable additional damage to the tank's systems, because they happened to not set off any additional ammo. A flash fire of powder can be over in less than a tenth of a second, and kills by overpressure (not burns).

As for HE vs tanks, it would be less effective than AP and by a long way, in most cases. Most of the physical energy of the round would be dissipated outside the tank. It might frag off antenas, smash external optics, or for lower hits, damage the suspension or tracks, but would not be particularly more effective at such things than AP hitting the same locations. The crew's "bells" would be rung either way, but tank crews lived through 155mm HE barrages with only a portion of the tanks losing tracks and the like.

Any actual direct hit by a 122mm round would dump a huge amount of energy onto the target in a very short period of time, and even if the armor held, could easily stun the crew. HE isn't needed for that effect and actually detracts from it - it scatters energy away from the axis of the round's flight.