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6 hours ago, SH_MM said:

Well, the mantlet is always a weak spot. But you are right, the slope is caused to provide maximum protection along a 30° arc. At 15° impact angle, the frontal armor will have a slope of 40° and an effective material thickness of 189 mm. The required protection was to stop a 105 mm APDS at 800 m distance. According to US documents, a 105 mm APDS penetrates 254 mm steel according at 1,500 m distance.

But we were ignoring the fact that tanks are not designed with protection from the direct front only in the previous discussion, thus I don't really see a big difference. The Leopard 2 would also have less than ~430 mm protection when hit at an impact angle of 30°.

I wasn't, which explains some of the discrepancy. I try to stick to some sort of generic 'frontal protection level'--so, yes, typically the minimum protection for the turret (often 30 degrees to each side--obviously not by coincidence). The minimal hull protection is, of course,  almost always 0 degrees, being unsloped when viewed from above.

So the original M1 is about 350 KE minimum (hull and turret)--but of course the turret from 0 degrees is more like 400. I generally assume those charts do the same--the British one from 1978 certainly does: armor protection "at [the] normal". So a "300mm" Leo-2 turret would be 350 at 0, and so on.

Brief interruption, carry on with the 2K discussion.

I think too much speculation is necessary to argue purely based on weight--small errors could result in large armor estimation differences so I find it to be a bit of a rabbit hole. We've all seen a million speculative assumptions that tank armor "had to be this" because of some weight or measured depth--and yet they usually end up being wrong. I certainly give your speculation more weight than average because it's well informed, but it's still speculation and it's outweighed by what (few) official docs we have for any of these vehicles.

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I think you might be misreading the graph. It shows the protection level in relation to the percentage of the surface area that achieves such a protection level.

I understand that. But I think it might be relatively easy to end up with 20% protection well over 300 on a tank whose practical protection level was 300 (or 325 or whatever). Not because the turret was 400, but because there are plenty of frontal shot paths--especially against the turret--that go through large swaths of oblique armor (turret sides, etc.).

But, hey, I accept that I could be overestimating those marginal areas and the diagram reflects a stronger turret as you say. That would certainly fit better with it's label as a 2A4, right? And if that's true, then it would support my low estimate of the 2A4 (a turret in the low 400's, a hull in the low 300's). Or do you have reason to believe that "Leopard 2A4" refers to the original armor? I don't see why they wouldn't have labelled it "Leopard 2" then.

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Based on the official data leaked by the Swedish trials, the Leopard 2-2A4 (1979-1987) had ~300 mm hull and ~430 mm turret armor protection against KE ammo, which matches with the other available sources and basic physics (more mass per area = better frontal armor protection).

OK, I see you read it as the original armor for some reason. Hmm, I'll read the posts again and see if I missed something there... No, it was just a guess. Maybe you found something in the German book which identifies Pakete B as being pre-upgrade armor?

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I think you posted a wrong link, because that is refering to an article on Andrei's website about Rheinmetall's 105 mm gun. Maybe you meant this graph from Krapke's 1986 book?

Sorry about that, you are correct--that's the chart I was looking for. However, I find it easy to interpret quite differently:

• As you know, NATO allies did not have a uniform set of threat estimates--so it's tricky to assume because the British determined a KE threat, the Germans shared that, but...
• NATO estimates for the 115mm gun were very consistent for a long time (360mm at 0km by the UK via Taylor, 330 @1km by the US via TRADOC #1 & 10, and so on).
• The 115mm gun was perceived by NATO as penetrating no more than the low 300's at 1km. (And that's what matters, not some premium round the Soviets had in somewhere in stock that NATO appears to have been ignorant of--you've made this same point more eloquently than I in this very thread).
• Keep in mind this same gun is shown penetrating the Leo-1 at 1.8km. I honestly haven't researched the Leo-1 improved turrets, but you're not saying they were in the high 300's are you?
• As for the 125mm gun, it seems that the Germans (or this one German) simply didn't rate it as high as the Brits. Otherwise it would also be shown penetrating the Leo-1 at a heck of a lot more than 3km. (This chart likewise underestimates the T-72's armor for that matter).

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...hence means that he either mixed up data from different variants (which would be stupid) or that he refers to the original production batches of the Leopard 2A4.

That's exactly what I think he did (intentionally or not--those mistakes happen quite frequently in presentations, so I don't think it's "stupid" regardless). After all, he's got a "Leopard 2A4" stretching back to 1979, so the versions are definitely mixed up. As I said, the slide is muddled by design or by mistake. At the very least, I'd say "it's not clear" which version he's referring to.

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The UK chart is interessting, but reading too much in a single number alone doesn't make sense.

Official charts with protection levels are rare and valuable. I feel I must give them a lot more weight than any of our amateur 'calculations' (mine included of course). Where on earth did they get that number? Their allies weren't lying to them and the US had clearly (and correctly) indicated the M1 spec. I'm not saying that makes me right--but I wouldn't trivialize such a document--I wish we had more like it!

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I'm sorry, but that is just pure bollocks. Got any source for your impression? Because according to declassified documents available in the UK National Archives,  Germany was the first choice as partner on tank and armor development for the UK. The FRG got access to the full Chobham armor technology three years before the United States (from the British perspective, the US was too much focused on Vietnam and therefore an unreliable partner for defending Europe). The UK and Germany started developing a common tank for both countries in 1972 (to replace the Chieftain and the Leopard 1), which was protected with a Chobham armor variant specifically optimized to meet the German requirements. This armor was known as Buckhorse armor. The co-development ended in 1977, because of different opinions on the conception (Germany didn't want to design a second Leopard 2, when they already were making the Leopard 2; the UK wanted a conventional tank like the Leopard 2).

Whoah, take it easy!  My source here is this excellent Polish article (Google Translate helps...).

• Rather limited information was shared with the Germans in 1970, "more" in 1972. It's not clear how far this extended into construction methods, however (p.119)
• In contrast, in 1973, the US received "full" information. (p.116)
• Germany was not "the first choice". While the US was approached very soon after the discovery of (NERA) in 1965, Germany was not until the early 70's--and only b/c the US had temporarily cooled in it's reception: "In the early seventies, the British realized that the fate of the Chieftain Mk.5/2 was uncertain, and the entry into service of a full replacement would take many years. Further attempts to interest the Americans in "Burlington" seemed not to be producing any results, and as a result British policy makers made contact with the Federal Republic of Germany." (p.118)

Something the Germans had in the late 70's was stolen by the Soviets and (presumably) incorporated into projects like the T-72B. I may be incorrectly interpreting that as inferior, but the US didn't seem too concerned with it as special armor (or the "Enigma" variant that showed up in the Iraq). And AFAICT, NATO has not pursued that "style" of NERA. Just a hunch though--could be wrong or unfairly impugning 'German Chobham'.

Anyway, I don't want to dwell on a side argument, as I respect the many well thought-out opinions here. I like my interpretation and you like yours and that's fine. Maybe some future docs will come up and clear the matter up!

P.S. Thanks for the great German article link, buried in there is this: ""The turret and hull [of the Leo-2A0] are equipped with state-of-the-art special armor, which provides almost unlimited protection against shaped charge projectiles and reduces the penetration power of Russian [KE] shells from the T-72 by about half compared to the Leopard 1." Guess that's subject to interpretation, but a rough idea anyway.

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The document actually says that the MBT-80 has higher protection against ATGMs and RPGs (or rather: it has a lower probability of being destroyed by ATGMs/RPGs) than the Abrams, as long as the hull is hidden behind terrain.

The PK might be dubious as it depends on how they weighted the attack angles, etc. So I lean toward the simpler formulation: "MBT80 is better protected against KE attack than XM1 whilst XM1 has better HEAT protection than MBT80".

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The Chieftain Mk 5/2 project from 1970 already was designed to resist large calibre shaped charge warheads (a 5.0 inch warhead and a 6.0 inch warhead with 60° cone angle), that were capable of penetrating 23 and 28 inches of steel armor (584 and 711 mm) which is more than what the XM1 Abrams was designed to resist.

The UK experimented pretty wildly with protection levels in the early Chobham days (mid 60's-70's). They ended up shifting--increasingly and quite rightly--toward KE protection, and perhaps the added weight there diminished their fervor for high CE. The M1 did indeed end up with a weirdly high CE given its spec. But it appears that all the way through to the M1A1, the US was laboring under the assumption that tanks needed more CE protection... MOAR!

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As pointed out earlier in this topic, the UK tested the early production model of the Leopard 2 with the initial armor package. Based on the leaked data and some reasonable assumptions (i.e. that the largest physicial thickness provides most protection), it would provide about as much protection as 430 mm armor steel at the turret front.

... The Leopard 2A4 production model from 1988 seems to have armor protection comparable to 540-550 mm steel at the turret front and about 425 mm at the hull front, which is roughly comparable to the T-72B and overall superior to the Chieftain with Stillbrew armor.

 

Hmm... these seem like excessively high numbers, especially for the initial armor package. I think the official-ish estimates of the Leo-2 initial armor spec suggests lower numbers:

• It was designed for a roughly similar spec as the XM1, whose final numbers met that spec. The US found the Leo-2 armor inferior--and possibly not just in coverage.
• The 1978 UK chart--accurate in other respects--gives the Leo-2 a mere 300 'frontal protection.' Could it have ended up a tad higher? Sure, but not by 100+mm I'd say.
• It'd be hard to interpret the Krapke 1986(?) chart as approaching those high values--row 7 is especially damning. A value in the low 300's would fit however.
• The Swedish "Leopard 2A4 vs Leopard 2 'Improved' " chart likewise supports low numbers. (Whatever the tank on the left is, it'd be hard to describe its overall protection level as much more than 300, and that middle graph suggests there was a subsequent averaging 450 tops). I'd say "wimpy tank" fits with original armor and "next wimpiest" tank fits with the first armor upgrade. If "wimpy tank" was the Leo-2A4 armor upgrade, then even my estimates are too high!
• Even Rolf Hilmes slippery slide refers to the updated (turret armor) package I think, not the original armor (obviously there was no Leo2A4 in 1979).

Long story short: Leo2A0 <=350 KE! Leo2A4 <=450 KE! But don't take my word for it, even the Germans knew the 80's Leo-2 and everything about it was overrated.  OK, that was going too far! Nonetheless, I do get the feeling that what fragmentary statements we have (these and a few others) correlate more probably with the low values rather than the high ones.

I'm only speaking of the original armor and the first upgrade. Speaking of which, was the first armor upgrade to the turret only--so the hull stayed the same?

P.S. FWIW, my impression is that initial German "Chobham"--such as it was--was inferior to contemporary UK & US work. It seems to me the US got the better of the armor technology deals, and the UK was more cautious in sharing with Germany during the FMBT collaboration.

4 hours ago, SH_MM said:

The British military believed that its ammo was incapable of defeating the T-80 during the Cold War,  but it was enough to deal with the T-64. Given that this document is from 1986, Stillbrew armor might not have been adopted on the Chieftain yet, hence the statement about the Chieftain's armor being defeated by all modern Soviet tank guns (which I suppose means 100 mm, 115 mm and 125 mm guns).

 

The Challenger 1's frontal turret armor is claimed to be comparable to Soviet tanks with ERA. That would most likely be the T-64BV, T-72AV and T-80BV, given the fact that NATO learned about the T-72B in ~1988 (at least the official NATO codename for it was "Soviet Medium Tank 1988") and T-80U in 1989 (US/NATO codename M1989). This would suggest that the Challenger 1's frontal armor might be 450-500 mm vs KE and ~1,000 mm vs shaped charge warheads.

 

andrei-bt.livejournal.com/788654.html

Thanks for sharing another fine doc. More evidence pointing broadly in the same direction. (The links below are also all in this thread IIRC).

I interpret the 1988 UK doc for KE protection as: Leo-2A4 < Stillbrew Chieftain < CH1 < CH2 < M1A1HA. The top number in the range is likely 600mm, and yet the CH2 should have "significantly" better KE than the CH1. IMO, one should assume the lowest possible KE for Stillbrew & CH1. Even 500 seems too high to fit into this 'formula'.

I can't find contemporary Soviet CE protection estimates from the UK. The US low-end in 1987 was perhaps 500-600. (Way back in time, the MBT-80 CE level of 600 IIRC was deemed inferior to the XM1, but sufficient nonetheless). If the UK had already fielded superior CE protection to the M1, I'd think they'd have mentioned it in the 1988 doc. Finally there is the "roughly comparable" statement, for which a tank of 500/1000 KE/CE is possibly too much of a stretch. All evidence suggests that 1986 models of the Leo-2 & M1 were pretty far below that. It's indirect reasoning, but I take this as low-end CE for the CH1... and a CH2 with 900 CE at best--i.e. similar enough to the M1A1HA that it was not worth remarking upon one way or the other in 1988.

P.S. The 100mm ..BM8 and ..BM20 rounds would be appropriate candidates to defeat the pre-Stillbrew Chieftain I'd think.

On 4/9/2018 at 6:58 AM, SH_MM said:

What are you exactly looking for? The T-72 protection requirements are taken from Zaloga and a Russian website.

If you still have the link to the Russian post, I'd love to check it out. I find Zaloga to be very hit or miss, so I'm hoping there's some additional support for that protection level... it does certainly sound familiar, but I'm having trouble tracking down where I read something similar.

Cheers

SH_MM, some of the protection level bullets are familiar, some less so. 

More specifically:

• The XM1 spec is thoroughly documented--Hunnicutt's "Abrams..." and other docs.
• The MBT80 is documented with in this thread.
• Some/all of the Leo-2AV spec is referenced elsewhere in the forum (still reading through it).
• The only reference to T-72 protection levels I've seen is a general comment in one of Zaloga's Osprey books(?)

It's a very nice summary, so I'd love to see the sources I'm missing that provide the additional specificity. My search terms may have failed me and I may have missed the links b/c I'm new to the site...

P.S. Greetings

• On 3/1/2018 at 7:54 AM, SH_MM said:

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  • That leaves us with the following (is there any easy way to add tables?):

  Tank type	T-72	Leopard 2K	Leopard 2AV	(X)M1 Abrams	MBT-80
  Weight	41 tonnes	up to 47.5 tonnes	56.935 tonnes	52.6 tonnes	(?)
  KE threat	105 mm "next-generation" AP(FS)DS from 500 m along ±30° from the centerline 14.5 mm - 20 mm AP allround (?)	105 mm APDS from 800 m along ±15° from the centerline (turret only), 90 mm AP(DS) from 1,500 m along ±15° from the centerline (hull), 20 mm AP from 100 m (upper portions of the hull sides) or from 500 m at 20° (lower portion) 14.5 mm AP from 100 m (engine comparment)	105 mm APFSDS with 38 mm core diameter (ammo for the smoothbore gun?) along ±30° from the centerline, 7.62 mm AP at 30 m (engine vents), 14.5 mm AP all-round (20 mm AP at crew compartment?)	115 mm APFSDS from 800 - 1,200 m range, 14.5 mm AP all-round (?)	125 mm APFSDS from 1,000 m range, 14.5 mm AP all-round
  CE threat	9M14 Malyutka (AT-3 Sagger) at ±30° from the centerline	None	MILAN warhead	127 mm HEAT warhead (TOW-1?) at ±25° from the centerline, 81 mm HEAT at 45° (crew compartment)	(?)
  Artillery threat	(?)	155 mm artillery fragments at 10 m	155 mm artillery fragments at 10-15 m, 155 mm artillery fragments at 25 m (vehicle rear), no protection required (cover above the tracks at the engine compartment)	95% protection against 155 mm splinters at 15 m (crew compartment), 57% protection elsewhere	155 mm splinters at 10 m