Contemporary Western Tank Rumble!

[SH_MM]

On 4/11/2019 at 8:09 PM, Scav said:

You actually found info on those?
Also, I assume that's just for the turret, I don't see any side hull armour.

So, for KE it can protect against a 125mm APFSDS round at 1500m but only an RPG-7 for CE, nothing more? 

(granted it's still quite good protection) 

 

There was an optional hull armor module for the frontal hull of the Leopard 1 tank, fitted to one of the "Leopard 1A6" prototypes. The protection levels I stated are however all for the turret.

 

The turret was able to resist a Soviet ATGM along a slightly larger arc than the 125 mm APFSDS round, but it isn't exactly specified what warhead is utilized; the missile in question (AT-3 Sagger) has been described by contemporary German documents to feature warheads reaching between 400 and 600 mm penetration against steel targets. "RPG-7" however usually refers to the basic PG-7/PG-7M/PG-7V warheads with just ~300 mm penetration and thus provides a much better idea about armor efficiency, specifically given the highly sloped cheeks of the SuperM48 and Leopard 1A6.

 

An armor package based on the same technology was also offered for the T-55 after the Cold War ended, protection against unspecified TOW missile along the frontal arc and against the RPG-7 from 360° was achieved (this packaged looked kind of similar to the Leopard C1's add-on armor modules).

 

 

[VertigoEx]

16 hours ago, SH_MM said:

It seems very questionable that the US military disclosed the composition of its armor at the height of the Cold War in an unclassified source available to the public. The usage of expensive titanium also would stay in conflict with the goal of making the Abrams an affordable main battle tank, being between 10-20 times as expensive as armor grade steel alloys and requiring special tools for machining.

 

It is possible that the author leaked the actual armor composition of the Abrams, but it seems more likely that he added his own speculations about the armor composition or mixed different arrays (maybe such a titanium NERA type was tested in the US) to come up with an explanation regarding "Chobham".

 

 

I think that you could be correct here. Or it could be one component of the armor mix of

 

Thermal sights also are in conflict with that goal. Depends on business and economic factors around such things in the late 1970s etc. The cost of titanium vs RHA or HHS could come down with economies of scale. The F-14 wing box is a good example of this. Once the sunk cost is accounted for the cost comes way down. So the USA certainly had the facilities to machine simple shapes out of 10-20mm titanium at the time.

 

The cost of one material in the armor being say 20,000 vs 2000 in 1980s USD isn't make or break for a budget, in light of the reality that, forging, machining DU is also astronomically high and the USA did invest billions in the 1980s to up armor the M1A1.

 

I do agree that this is far from proof of anything.  Another small clue that just prompts more questions then answers.

[Wiedzmin]

On 5/11/2019 at 1:03 AM, SH_MM said:

The weight

it's funny to read about all this "weights!11"

 

for example T-72A hull front (UFP + LFP) 3+ tons IIRC

oplot-m hull front(UFP + LFP+"ERA cassette(without ERA blocks inside)" which is part of UFP) 4966kg

 

CR1 UFP special armour - 1.4 tons (1427 kg) (hull itself with special armour, fuel,ammo,engine etc isnide - 41700kg)

 

 

[Liberator]

24 minutes ago, Wiedzmin said:

it's funny to read about all this "weights!11"

 

for example T-72A hull front (UFP + LFP) 3+ tons IIRC

oplot-m hull front(UFP + LFP+"ERA cassette(withour ERA blocks inside)" which is part of UFP) 4966kg

 

CR1 UFP special armour - 1.4 tons (1427 kg)

Would like to clarify what specifically is included in this? Is it mass of whole UPF or only special armor?

[Wiedzmin]

7 minutes ago, Liberator said:

s it mass of whole UPF or only special armor?

for soviet tanks whole UFP(as i wrote - UFP( in case of soviet tanks UFP structure is special armour basically,because only whole structure gives protection, but not 2/3/4/any number sheets of FPR from whole structure )  + LFP + some other in case of oplot) + LFP

 

in case of CR1 weight of special armour module(spaced armour plates, mild steel plates on plastic, fasteners etc)

 

 

one more example

 

Biscuit №4 was 406mm thick(50mm of those 406 was RHA backing plate, so 356mm for special armour), whole assembly have weight similar to 5,3 inch steel plate(135mm)

[Liberator]

20 minutes ago, Wiedzmin said:

for soviet tanks whole UFP(as i wrote - UFP( in case of soviet tanks UFP structure is special armour basically,because only whole structure gives protection, but not 2/3/4/any number sheets of FPR from whole structure )  + LFP + some other in case of oplot) + LFP

 

in case of CR1 weight of special armour module(spaced armour plates, mild steel plates on plastic, fasteners etc)

 

 

one more example

 

Biscuit №4 was 406mm thick(50mm of those 406 was RHA backing plate, so 356mm for special armour), whole assembly have weight similar to 5,3 inch steel plate(135mm)

Hmm, this is interesting. Are there exact numbers on mass of UPF+LPF T-72A?
Did you mention mild steel plates, is there any more accurate data? (Hardness or maybe steel grade or some other data?)

[Wiedzmin]

4 minutes ago, Liberator said:

Are there exact numbers on mass of UPF+LPF T-72A?

i can find exact "kg" but it will take some time

 

4 minutes ago, Liberator said:

Did you mention mild steel plates, is there any more accurate data? (Hardness or maybe steel grade or some other data?)

this is only description what i seen in reports about chobham biscuits, few spaced armor plates which is protects  agains KE, and package of mild steel on plastic(NERA) to protect from CE

[Liberator]

11 minutes ago, Wiedzmin said:

i can find exact "kg" but it will take some time

 

this is only description what i seen in reports about chobham biscuits, few spaced armor plates which is protects  agains KE, and package of mild steel on plastic(NERA) to protect from CE

thank)
Does this mass include various external elements on the UFP? And LFP:

 

 

also read about it, thought that maybe you know a little more about the materials.

[Wiedzmin]

11 hours ago, Liberator said:

Does this mass include various external elements on the UFP?

no, only UFP and LFP itself without any addons, without idlers housings, blade etc, even without driver vision block and plate(and without 16mm add-on) for it IIRC

 

 

upd: UFP(without 16mm addon, without driver plate for vision block and any other additions, but only with tow hooks) + LFP(499kg) - 3517kg, so UFP alone with hooks - 3018 kg

[Scav]

On 5/11/2019 at 12:03 AM, SH_MM said:

This is all just speculation on your part.

Ofcourse there's speculation in what I say, there's speculation in almost everything regarding classified vehicles like the MBTs we're talking about.

You yourself even speculate in the same paragraph:

On 5/11/2019 at 12:03 AM, SH_MM said:

Another problem is that you ignore the fact that MBTs are built for protection along a frontal arc; the available sources do not say "the Leopard 2AV can only resist the 105 mm APFSDS and MILAN ATGM at the thickest part of its turret when hit directly from the front", so it is very reasonable to assume that the tank was required to resist the reference threats along a greater area. The hull armor of the Leopard 2 is just 600-650 mm thick, which even against the basic MILAN would result to a ratio between stopped penetration and armor thickness of up to 0.88 - rather close to the values you used for the M1 Abrams.

Right there you speculate the requirement also includes protection for the frontal arc (inc side armour), you even speculate it includes the hull!

There's nothing in that snippet which talks about the hull, merely that the armour is "assumed" to be protected against these threats, it doesn't specify arc, nor range, nor part of the armour.

 

Do I think it's possible it also includes the hull?
Yeah, perhaps, but not the lower hull, nor do I think protecting against 105mm DM13 (APFSDS) is that easy, you essentially need T-72M levels of upper hull armour, if not a bit more (T-72M1).

Why do I think so?
Because https://fromtheswedisharchives.wordpress.com/2019/01/03/rheinmetall-105-cm-smoothbore-performance/ gives us performance for DM13 APFSDS and what looks to be M111 (32mm core, matches that of M111 and I cannot think of any more probable round that it could refer to).

The performance figures for a 150mm plate @ 60°:

Spoiler

Interestingly, DM13 penetrates the plate as low as 1329m/s, while M111 fails at 1379m/s, which could indate that atleast against monolithic targets, DM13 performs slightly better.

It gets even more interesting when we look at the third target, a 40mm plate + 150mm air + 90mm plate (all at 60°)

Here DM13 has a ~100m/s advantage over M111 (at ~75m/s velocity drop over 1000m that means about 1.25km range advantage).

Spoiler

So, if M111 could penetrate T-72Ms from about 800-1200m and DM13 (105 APFSDS) was better than this, I don't see the leopard 2 hull stopping it below 1500m.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

The M1 Abrams and the MBT 80 were designed to resist the reference threats along a 50° frontal arc (for the turret at least), thus the Abrams' turret side armor with a thickness of 317.5 mm is relevant, which has more or less the same thickness as the Leopard 2's turret side armor at 310-330 mm. If the MILAN warhead was placed at an increased stand-off distance, then you are essentially looking at the same thickness of armor providing the same level of protection!

So, assuming worst case scenario for M1 and best case for leo 2, that's how you get them to have almost equal side turret armour?
I don't do that, assuming equal testing methods (which they probably are considering there's NATO standards), the M1s turret side is still better for equal LOS than the leo 2s (against CE). 

 

On 5/11/2019 at 12:03 AM, SH_MM said:

Another possibility would be that Leopard 2's turret could be required to stop the MILAN warhead at built-in stand-off distance along a 60° arc - then again the ratio between stopped penetration and LOS thickness would be very similar.

 

You are trying to support a theory with an hypothesis.

I'm looking at what's most probable given available info, and sharing that idea so I can get constructive criticism, but I don't assume best case scenario like what you said there.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

This is not the case. The Challenger 1 was required to stop a certain simulated 125 mm APFSDS round at a distance of 1,000 m.

Assessed as being able to stop an estimated round at ranges above 1km.*

Spoiler

FYI, this document is from 1980-1981: https://discovery.nationalarchives.gov.uk/details/r/C16517036

 

On 5/11/2019 at 12:03 AM, SH_MM said:

Again: The only reason why the Swiss source remains somewhat relevant is the fact that the values were used for a graphic in the Krapke's book. However there are many possible reasons why this doesn't confirm them: Where the drawings made/checked by Krapke? Was he allowed to disclose the protection levels/requirements in such a way or not? Did he use these values, because they were the only publicly published protection estimates? Did he use them, because they say that the turret front resist a 115 mm APFSDS from 1,000 m distance (which not only is a contradiction in the Swiss magazine, but also might be closer to the real requirements)? Or because he wrote multiple articles in the same magazine and didn't want to "backstab" his colleagues?

I was going off Krapke's diagram.

If you're worried he's wrong about something like this, why aren't you worried about a vague term like "Beulblechpanzerung"?

 

On 5/11/2019 at 12:03 AM, SH_MM said:

There is currently no evidence that any simulant has been used to test the original model of the Leopard 2 against a any sort of 125 mm APFSDS from 1,500 m distance.

Neither is there for CR1 or M1, only on paper.

Besides, if you're going to assume the CR1 was tested against 125mm simulants, might as well do the same for leo 2.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

Yet you are the one falling back to the techniques by Mr. Lakowski: you are making up an armor array/armor type and pretending that this has to be the one armor type used by the tank, despite having no source that such armor was ever fielded (or would be effective in any way). The Leopard 2's armor has been described as Beulblechpanzerung even back when Chobham had still been described as "ceramic honeycomb armor embedded in steel".

And you don't think "Beulblechpanzerung" might not refer to the armour type you think it refers to?

It's a vague term, only describing what happens, not how it happens, never mind the exact composition or layering to achieve the effect.

That is what I really have an issue with, the fact it might not be "conventional" chobham, yet lots of people seem to think it is.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

The author of the blog used to post here for a brief amount of time, but he was banned (or just stopped posting?) for starting a flame war with another, more respected member, where he refused to acknowledge sources disproving his theory. While he has made a very well write-up on armor technology (mainly because he consistently updates it, we also wanted to cooperate back when I still used to blog), he has been always very enthusiastic (a bit too much) about the capabilties of Soviet armor, where his estimations end up being often being best-case estimates with the papers used as sources being best-case laboratory results that he simply "translates" (sometimes by guessing) to.

Interesting, I myself found some of what he said a bit "enthusiastic" as well, but overal, most of what he says is backed up by valid sources and "logic".

Specifically his explanations and points regarding the Soviet UFP armour seem to be rather accurate, albeit a tad high in some cases.

 

Quite clearly though, if we assume NATO armour increased in mass efficiency over the years, we have to assume the same for USSR armour arrays.

Besides, what other reason could they have for ditching the textolite in the T-72AV and going thinner spaced plates (which could be more easily destroyed or damaged)?

If the T-72AVs armour wasn't more mass efficient than the T-64B/T-80BVs, why use it?

 

On 5/11/2019 at 12:03 AM, SH_MM said:

There are still a few errors in the current version of the article, like e.g. that Kontakt-1 would be useful against DM12/M830.

Curious, why wouldn't it be?
I mean, he did underestimate that round in particular (~450mm vs actual ~650mm), but is there some other element that he failed to mention?

 

On 5/11/2019 at 12:03 AM, SH_MM said:

The Mk. 1 is more or less a pre-series model, not having all specified features. The Challenger 1 Mk. 2 however has a weight of 62.5 metric tons based on an actual sales brochure from Vickers Defence Systems. The weight difference between Shir 2, Challenger 1 Mk. 1 and Challenger 1 Mk. 2 could be attributed to several factors, jumping to conclusions without having access to more detailed sources seems to be silly. I haven't seen a source noting a weight of 59.5 metric tons for the Challenger 1 Mk. 1 that was published after the actual tank entered service, thus the lower weight it might refer to a prototype proposal before the turret armor was reinforced.

Apart from TOGS, what do you think they added that could weigh ~3t?
Personally think automotive change, but that wouldn't account for it.

Anyway, this isn't a prototype or whatever it's talking about, this is the production CR1 Mk1:

Spoiler

last changed: 14/3/83 after CR1 entered service.

Shir 2 was scheduled for production in April of 1979, but cancelled in Feb of 1979.

It was found to be "unsatisfactory" in terms of fire control systems primarily, with the UK going for the MBT-80....
But then in 1979 they realised it wasn't feasable and they decided to buy a limited number of FV4030/3 (Shir 2) in Sept 1979, but without major modifications.

Personally, I'd class "improved turret protection" under "major modification", especially considering the cast base turret of the design already made it weaker than if it were RHA.

All the secondary sources I've been able to find indicate that only automotive/gunnery trials were held, no changes in armour are mentioned.

In dec of 1982 it was then accepted, but they should fix some issues:

• TN37 Gearbox (problematic apparently)
• Fightability
• Scale of major assembly spares
• Main engine generator drive
• Neodymium YAG Laser sight
• Tools and test equipment

None of that would increase weight by that much.

Oh, and the tank entered service officially on the 16th of March in 1983 (handed over to the troops).

That's two days after the source I've been using for the weight....

 

 

More specs:

Spoiler

Interesting to note is how much bigger CR1 is compared to M1.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

You are again choosing one interpretation and assuming that it is true. There are many possible options how "slightly higher protection" does not invalidate a turret protection level of 500 mm steel equivalent protection vs KE. Having a lower level of hull protection (275 mm per the declassified document) and having a better protected turret can average out as "slightly higher protection".

In a UK doc?
They'd say it's a notable improvement still, even then the 275mm you're using for the hull comes from the same document here:

Spoiler

It doesn't say "275mm", it says "a minimum protection equivalent to 275mm".

This could mean a variety of things, possibly that the "shoulders" of the UFP are less armoured than the middle section, or something else.

But it doesn't say 275mm for the UFP, that would be 50mm lower than the Shir 2 had.....

 

On 5/11/2019 at 12:03 AM, SH_MM said:

Or a computer analysis taking into account penetration values, impact angles and surface areas could be used to determine the probability of being killed/destroyed, something we know the British military has made for the Chieftain, MBT80, Challenger 1 and XM1 Abrams/M1 Abrams FSED. Depending on the amount and types of threats taken into account and the weighing used, a difference between 350 mm and 500 mm turret armor could result in just slightly higher survivability (lower probability of being destroyed).

While I agree that survivability is hard to quantify or dependant on what you're looking at, that doesn't mean that all of a sudden the UK only considers their new tank (which according to you offers around 500mm for the turret, close to MBT-80) as "slightly" better protected.

If you assume 325mm KE protection on the hull (Shir 2 values) and ~500mm on the turret, you have to weigh the side protection a lot higher than the frontal protection for the M1 to only be "slightly" worse.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

The overall weight of the Vickers Mk. 7/2 is 54.64 metric tons. Given that the hull is taken from the Leopard 2 and that its turret likely has a larger amount of weight allocated for non-special armor parts (wider turret should indicate a higher weight of the steel citadel, longer barrel also weighs more). If the Leopard 2 has approximately 5.4 metric tons of special armor, the Vickers Mk. 7 should have less (!) than five metric tons of special armor. This is roughly 40% less special armor than the Challenger 1, while the armored surface is identical.

And source for the Vicker's weight is?
It could use newer armour when compared to Challenger 1 which seems to just be a Shir 2 in armour technology.

After all, it was developed in 1984-1988(?) to replace Challenger 1 and/or be used for export.

It was a later design and could incorporate new armour technology.

 

You're ignoring that the hull is smaller, lighter and has less armoured surface area compared to CR1.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

You are only speculating again without having a source stating exactly what you believe it would (such as your interpretation of generic/ambiguous statements such as "APDS, APFSDS such as the quoted Russian round"). The figures quoted in the Haynes' book on the Chieftain were outdated at the time of the Challenger 1's requirement/design documents were written.

Speculating?
It clearly mentions what I say and it doesn't take much to see how a "successor" 125mm round with an estimated performance substantially higher than L23, yet somehow about as capable as L23 in the eyes of the UK, has to be considered "inferior" in design for that assumption to work.

 

If those figures came from the Stillbrew study (feasibility study of improving chieftain turret protection), then they're more recent than the Challenger 1's requirement, as that study is from after 1981 when the UK got the chance to inspect destroyed Iranian Chieftains.

 

Unless they now assumed the USSRs rounds to be worse than before, I don't see why the values would be "outdated".

 

On 5/11/2019 at 12:03 AM, SH_MM said:

There were many different estimates for different types of Soviet ammunition in the time frame relevant for Chieftain's Stillbrew armor package and the Challenger 1's development. But the requirements always were focused on specific ones (i.e. Chieftain's Stillbrew protected against one specific type of 125 mm APFSDS), not on all rounds. The round used to test Stillbrew might have been inferior to L23, but the rounds used as reference for the MBT 80 and CR1 programs were more capable than L23.

How is this possible if the MBT-80 study was ended in 1979 (L23 still in development) and CR1 was finalised before the end of 1982 (L23 still not introduced)?

They tested the Stillbrew package in 1985, after L23 was introduced and when BD26 was well underway, so if anything, the Stillbrew package was probably tested with superior ammo.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

For the MBT 80, even more powerful APFSDS ammo was considered for the protection requirements, i.e. the M1980 APFSDS with DU staballoy penetrator, believed to defeat 600 mm steel armor at point-blanc and 540 mm at 1,000 m distance. Full protection along the frontal arc against such a round would have resulted in a weight of above MLC70 in case of the MBT 80, which previously was designed to fit within MLC60. As this wasn't reasonable, protection requirements were lowered (no protection against DU APFSDS at shorter ranges, less area of the hull covered by armor) -

Initial requirement called for 430mm+ worth of protection on hull and turret, this was lowered to 405mm when they increased the HEAT protection.
At this point they didn't have APFSDS that could even reach it, nor alloys for such rounds, so this was purely theorising and best case scenario in terms of armour capability.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

the Challenger 1 is a continuation of this lowered requirements, having also reduced hull armor protection (275 mm required protection per the design document), while a similar (62 metric tons) concept for the MBT 80 had equal protection levels on turret and hull (480 mm) - this makes perfectly sense, given that the Challenger 1 is a less weight-efficient design, not making use of the partially aluminium construction developed for the MBT 80.

Same hull as Shir 2, same weight as MBT-80, fully steel (apart from roadwheels), so I highly doubt same turret armour.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

Source?

Hull definitely didn't change from Shir 2 to CR1, turret most probably didn't, Shir 2 was developed in the mid 70s before UK was convinced to switch to APFSDS and way before they even had their own APFSDS.

Just in 1970 they had been testing Chobham against 120mm APDS and only stopping at at 1300m, you really think they managed to suddenly optimise the armour against a new type of round they had little to no experience with and which also performed substantially differently and better than APDS?

 

Shir 2 was for export to Iran, highly doubt they would've designed the armour to defeat ammo (115mm APFSDS) they didn't think was that impressive (considered equal to 105mm APDS in 1970).

No secondary sources say anything about armour upgrades between Shir 2 and CR1, no visual difference regarding thickness of armour, urgency to put the tank into production, weight limit......

All these things contribute and point to the CR1 having near identical performing armour to the Shir 2.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

The weight of the Challenger 1's special armor is 6,925 kilograms as stated by Wiedzmin in another discussion. The armor layout is less efficient in terms of coverage to allow the covered places to feature thicker armor.

And his source for this was?

What?

If you're referring to the preference of not using highly sloping armour plates for the top of the hull and instead "pulling up" the armour to cover that area, leaving the LFP exposed, then yes, it's less efficient in terms of coverage and does make that area thicker, but that was my point.

 

The armour layout is simply less efficient than that of leopard 2 or M1, by "pulling up" the armour on the UFP, it makes the front of the hull higher and thus means more volume/weight, only leaving a thin LFP to protect the lower hull.

Just compare both of these:

Spoiler

Clearly, the Challenger 1s armour is spread over a larger area and protects areas that the leopard 2 does not (highly sloped UFP and "shoulders").

In turn the leopard 2 doesn't have a driver's hatch and features composite in the lower plate (albeit substantially thinner than the rest).

 

On 5/11/2019 at 12:03 AM, SH_MM said:

Highly sloped armor is not more weight efficient, if you take a look at the hull protection (275 mm steel equivalent protection for CR1 weighs less than a the 200-280 mm LOS steel of M1 and Leopard 2).

Except that it's not counted as composite and reduces the surface area that needs to be covered by composite, thereby indirectly making it a more weight efficient method if we only count the composite weight.

Also, again, 325mm if we go by Shir 2 numbers....

 

On 5/11/2019 at 12:03 AM, SH_MM said:

The hull armor layout of the Challenger 1 seems to provide less (full) coverage than that of the Leopard 2 while the protection level is lowered (at least assuming that the design document requiring 275 mm is just met and the Swedish leaks are accurate),

It protects the sponsons and gets closer to the turret base of the leopard 2, so more area covered, albeit less consistently.

Protection level is again, not lower, but about the same if not ever so slightly higher.

 

On 5/11/2019 at 12:03 AM, SH_MM said:

thus the hull armor might have a lower overall weight for the Challenger 1.

Larger profile and higher volume of frontal hull armour, which means same weight and lower density or higher weight and same density.
 

On 5/11/2019 at 12:03 AM, SH_MM said:

It has a somewhat larger area of the turret covered by special armor, but not enough to offset the 30% larger weight of the Challenger 1's special armor compared to the Leopard 2's. Add to this the speculated heavier backplate of the CR1's armor array and it seems very clear that Challenger 1 reaches a higher level of turret armor protection than the Leopard 2.

Larger area covered, unconfirmed weight, cast base turret and similar LOS to leopard 2 front armour, I don't see how it can be much better.

(Possibly older armour technology and more optimised against HEAT as well)

[Molota_477]

CR1 UFP without cover

 

According to the report "Operational Requirements Committte, The Requirement to take Challenger Tanks into Service in the British Army, 7th August 1979'', CR1's turret front has a specified protection level of 480KE/600CE

[Molota_477]

19 hours ago, Wiedzmin said:

Biscuit №4 was 406mm thick(50mm of those 406 was RHA backing plate, so 356mm for special armour), whole assembly have weight similar to 5,3 inch steel plate(135mm)

Interesting that the No.4 array had been mentioned in a report of Chieftain mk5/2, would you mind share the source of this message?  Title of report is ok.

[Liberator]

1 hour ago, Molota_477 said:

CR1 UFP without cover

 

According to the report "Operational Requirements Committte, The Requirement to take Challenger Tanks into Service in the British Army, 7th August 1979'', CR1's turret front has a specified protection level of 480KE/600CE

Do they say this is the level of protection for frontal arc?

[Molota_477]

1 hour ago, Liberator said:

Do they say this is the level of protection for frontal arc?

The initial Equipment  Requirment of GSR3574  defined that CR1's turret must retain the minimum protection requirement of MBT-80, which should withstand 600mm CE and revised 480mm KE within ± 25° front arc.

But as for hull front, because of the steel structure was too heavy, only required significant improvement against HEAT than Chieftain while KE resistance not less than Chieftain.( Only needed to against 85mm HEAT)

 

 

[Liberator]

31 minutes ago, Molota_477 said:

The initial Equipment  Requirment of GSR3574  defined that CR1's turret must retain the minimum protection requirement of MBT-80, which should withstand 600mm CE and revised 480mm KE within ± 25° front arc.

But as for hull front, because of the steel structure was too heavy, only required significant improvement against HEAT than Chieftain while KE resistance not less than Chieftain.( Only needed to against 85mm HEAT)

 

 

It is strange that the angles are + -25 °, although turret angles have +-30 °. Although perhaps this is due to fact that early data?

And yet it is interesting whether CR 1 Mk.1 really had a weight 59.5 tons, and CR 1 Mk.2 already had 62 tons. Does anyone have more accurate data on this?

[Molota_477]

8 hours ago, Scav said:

Because https://fromtheswedisharchives.wordpress.com/2019/01/03/rheinmetall-105-cm-smoothbore-performance/ gives us performance for DM13 APFSDS and what looks to be M111 (32mm core, matches that of M111 and I cannot think of any more probable round that it could refer to).

The performance figures for a 150mm plate @ 60°:

  Reveal hidden contents

Interestingly, DM13 penetrates the plate as low as 1329m/s, while M111 fails at 1379m/s, which could indate that atleast against monolithic targets, DM13 performs slightly better.

It gets even more interesting when we look at the third target, a 40mm plate + 150mm air + 90mm plate (all at 60°)

Here DM13 has a ~100m/s advantage over M111 (at ~75m/s velocity drop over 1000m that means about 1.25km range advantage).

I don't think that is M111, it might be some type of experimental sheated APFSDS but with 32mm dia.

 

There are plenty data of M111 in Chinese:

Its V50 of againsting 150mm/60° target is about 1260m/s

[Molota_477]

6 minutes ago, Liberator said:

It is strange that the angles are + -25 °, although turret angles have +-30 °. Although perhaps this is due to fact that early data?

And yet it is interesting whether CR 1 Mk.1 really had a weight 59.5 tons, and CR 1 Mk.2 already had 62 tons. Does anyone have more accurate data on this?

Indeed the requirement data can not represent the implemented protection level,  the GSR3574 had already restricted the weight is 62 tonnes.

 

Edit:

There are some interesting armor weight data of MBT80 here:

To against the 430mm KE threat(Original GSR 3572), the turret armor weight —— 6045kg

As for 480mm KE threat—— 6880kg

And 540mm KE threat —— 7495kg

While Challenger only estimated to have 5498kg of armor on the turret.

 

[Liberator]

18 minutes ago, Molota_477 said:

Indeed the requirement data can not represent the implemented protection level,  the GSR3574 had already restricted the weight is 62 tonnes.

 

Edit:

There are some interesting armor weight data of MBT80 here:

To against the 430mm KE threat(Original GSR 3572), the turret armor weight —— 6045kg

As for 480mm KE threat—— 6880kg

And 540mm KE threat —— 7495kg

While Challenger only estimated to have 5498kg of armor on the turret.

 

as far as I know, the MBT-80 should have a completely different form turret. But then again, as I understand it all applies to 1979-1980

[Scav]

5 hours ago, Molota_477 said:

I don't think that is M111, it might be some type of experimental sheated APFSDS but with 32mm dia.

Unfortunately there's no pictures to confirm, M111 (or prototype thereof) seemed rather likely as the diameter is the same and I haven't seen any other round that could be used that has the same diameter.

If it was a different prototype round, it's unknown.

 

8 hours ago, Molota_477 said:

CR1 UFP without cover

Nice pic,

 

8 hours ago, Molota_477 said:

According to the report "Operational Requirements Committte, The Requirement to take Challenger Tanks into Service in the British Army, 7th August 1979'', CR1's turret front has a specified protection level of 480KE/600CE

But then the HEAT protection specified in a later document wouldn't be achieved, and "480mm" is again higher than what they settled on for MBT-80 while also not specifying what round it is against.

 

6 hours ago, Molota_477 said:

The initial Equipment  Requirment of GSR3574  defined that CR1's turret must retain the minimum protection requirement of MBT-80, which should withstand 600mm CE and revised 480mm KE within ± 25° front arc.

But as for hull front, because of the steel structure was too heavy, only required significant improvement against HEAT than Chieftain while KE resistance not less than Chieftain.( Only needed to against 85mm HEAT)

That's weird, MBT-80 settled on ~405mm KE requirement and ~850mm CE.

 

5 hours ago, Molota_477 said:

Indeed the requirement data can not represent the implemented protection level,  the GSR3574 had already restricted the weight is 62 tonnes.

 

Edit:

There are some interesting armor weight data of MBT80 here:

To against the 430mm KE threat(Original GSR 3572), the turret armor weight —— 6045kg

As for 480mm KE threat—— 6880kg

And 540mm KE threat —— 7495kg

While Challenger only estimated to have 5498kg of armor on the turret.

Yeah, this is pretty much why I don't believe that it could achieve 500mm (atleast against long rods, against slug type 125mm ammo it definitely might).

 

Can you link where you got these weights?
I've been trying to gather more info, I don't have access to the archives directly.

[SH_MM]

15 hours ago, Scav said:

Right there you speculate the requirement also includes protection for the frontal arc (inc side armour), you even speculate it includes the hull! 

 

According to Paul-Werner Krapke, the protection of the Leopard 2 has been focused on a certain (not specified) frontal arc. It is illustrated with a sketch in his book, which shows a top view of the tank (hull and turret) and small arrows/triangles with different shading facing the tank. The side armor is always part of the frontal arc.

 

Based on the declassified protocol describing a number of changes (to be) made during the transisition period from Leopard 2AV to Leopard 2, the hull armor was to be reconstructed (replacing the weight-wise inefficient fuel tank with layers of special armor) without a change in armor protection. The Leopard 2AV hull was specifically designed to meet the German interpretation of the US Army protection requirements for the XM1 tank program. The XM1 is - based on declassified British documents (and by extension the Swedish leaks) - required to provide very similar armor protection at the hull (i.e. resistance to 115 mm APFSDS from a 400 metres greater distance and 127 mm shaped charge warhead) along a certain frontal arc. The fact that the hull protection of the Leopard 2 is quite beefy and also focused on a certain frontal arc is illustrated by its rather thick side skirts, which at 110 mm are thicker than anything fielded on contemporary tanks (minus applique armor packages).

 

Also note that the protocol mentioning several changes made from the transisiton between Leopard 2AV and Leopard 2 mentions that protection has to be provided for the hull only at 900 mm above the ground (meaning the lower front plate is not reaching the same level of protection).

 

15 hours ago, Scav said:

So, if M111 could penetrate T-72Ms from about 800-1200m and DM13 (105 APFSDS) was better than this, I don't see the leopard 2 hull stopping it below 1500m.

 

This is again very speculative. First of all, M111 is a lot better than the 105 mm KE/38. According to Krapke, the development of the 105 mm smoothbore gun by Rheinmetall and the corresponding ammunition was halted after an "improved 105 mm round M735" managed to essentially match the performance despite being fired from the rifled M68 gun. It is not mentioned how this round was improved (Better propellant? Prototype with better tungsten alloy composition? M735A1 with DU penetrator?), but West-Germany decided that the smoothbore version wouldn't offer enough growth potential over the rifled L7A3/M68 gun to make funding the further development a reasonable investment. Some Leopard 2 prototypes were therefore re-gunned with the L7A3.

 

The M111 proved to be superior to the M735 and therefore chosen by the West-German military for the Leopard 1 as 105 mm DM23 APFSDS. It was the first monobloc APFSDS and therefore could defeat complex armor arrays a lot better.

 

The Swedish tests of Rheinmetall's 105 mm smoothbore gun are very interesting, but unfortunately they don't tell us anything about the actual performance of the round outside the test conditions and do not contain enough information to make them applicable to other cases. What is the normal propellant charge size used for the 105 mm KE/38? What is the muzzle velocity? What is the velocity loss per 1,000 metres traveled?

Really important factors are not mentioned in the document, so we have to look at other documents and assume that they are based on similar prototypes with similiar performance; but these documents provide rather conflicting - or questionable - data. For example according to tables summarizing the trilateral gun trials (which is based on a British report), the velocity loss for the APFSDS ammunition fired by Rheinmetall's 105 mm smoothbore gun is 100 m/s per kilometre. Yet later data for the 120 mm DM13 APFSDS shows a better velocity retention.

 

Also note how soft the steel used in the Swedish tests is: 255 HB, while the turret structure of the Leopard 2 was apparently made of HFX-130 steel with a strength of 1,300 N/mm (equivalent mean hardness 383 HB). How much is the protection loss from using such soft steel plates? 10%, 20% or more? Supposedly the Soviets rated the cast armor used on T-55, T-62 and T-72 (hardness 260-280 HB) as 5% to 15% less effective against armor-piercing ammunition than the rolled steel plates utilized for the hulls (hardness ~300-350 HB).

 

15 hours ago, Scav said:

Besides, if you're going to assume the CR1 was tested against 125mm simulants, might as well do the same for leo 2. 

 

No, that would be a very silly thing to do.

I assume that the Challenger 1 was tested against a simulated 125 mm APFSDS round, because it was required to protect against a certain (fictive) 125 mm APFSDS round. The Leopard 2 from 1979 was not required to defeat such a round, as its armor protection requirements were apparently focused on 115 mm APFSDS rounds (NATO being unsure about the existance of the 125 mm gun by the mid-1970s) simulated by the 105 mm KE/38.

 

15 hours ago, Scav said:

And you don't think "Beulblechpanzerung" might not refer to the armour type you think it refers to? 

It's a vague term, only describing what happens, not how it happens, never mind the exact composition or layering to achieve the effect. 

 

It is not a vague term and has only been used to describe one specific type of armor (sandwich of an elastic material and steel plates). For other types of armor, there are other terms.

 

15 hours ago, Scav said:

If the T-72AVs armour wasn't more mass efficient than the T-64B/T-80BVs, why use it?

 

Space efficiency. T-80BV has ~400 mm steel along the line-of-sight for an armor thickness (LOS) of 587 mm, the T-72AV has ~413 mm steel along the line-of-sight for an armor thickness (LOS) of 573 mm, while the early T-72B had ~453 mm steel along the line-of-sight for an armor thickness (LOS) of 587 mm.

 

Also note that my previous statements were focused on comparing different potential layouts of spaced armor, not spaced armor versus laminated armor utilizing textolites; although the latter seems to be more effective per weight at stopping shaped charge warheads.

 

15 hours ago, Scav said:

Curious, why wouldn't it be?

 

Kinetic energy. At ~1,000 m/s velocity, the tip can travel 60 mm before the shaped charge jet has fully formed and exited the projectile. Sure, at longer distances the muzzle velocity of DM12/M830 will be a bit lower, but the problem will remain.

 

To stop HEAT-FS rounds, a sufficient thick steel plate needs to be placed in front of the ERA, so that the warhead is initiated before the round pases through the explosive reactive sandwich. The box of Kontakt-1 was too thin to set off the fuze, only with Kontakt-5  ERA became sufficient against HEAT-FS rounds.

 

15 hours ago, Scav said:

last changed: 14/3/83 after CR1 entered service. 

Shir 2 was scheduled for production in April of 1979, but cancelled in Feb of 1979.

It was found to be "unsatisfactory" in terms of fire control systems primarily, with the UK going for the MBT-80....
But then in 1979 they realised it wasn't feasable and they decided to buy a limited number of FV4030/3 (Shir 2) in Sept 1979, but without major modifications. 

 

"Last changed" doesn't equal "all values and statements were updated", you can find quite a few examples in declassified British documents where figures weren't updated despite later changes to parts of them.

 

Aside of that, just look at what you previously wrote:

- Challenger 1 supposedly weighed 59.5 metric tons, but Shir 2 would weigh up to 62 metric tons -> therefore CR1's armor is supposed to be weaker

- Shir 2 was adopted as Challenger 1 "without major modifications"...

 

So where did the excess weight go?

 

Also the Shir 2 was rather dramatically modified before turning into the Challenger 1, e.g. the turret armor was improved as mentioned in British documenets, as I previously posted.

 

15 hours ago, Scav said:

Initial requirement called for 430mm+ worth of protection on hull and turret, this was lowered to 405mm when they increased the HEAT protection.

 

... and then again new protection requirements were made after the Soviet 125 mm gun was recognized as a more capable threat.

 

15 hours ago, Scav said:

The armour layout is simply less efficient than that of leopard 2 or M1, by "pulling up" the armour on the UFP, it makes the front of the hull higher and thus means more volume/weight, only leaving a thin LFP to protect the lower hull.

Just compare both of these: 

  Reveal hidden contents

Clearly, the Challenger 1s armour is spread over a larger area and protects areas that the leopard 2 does not (highly sloped UFP and "shoulders").

In turn the leopard 2 doesn't have a driver's hatch and features composite in the lower plate (albeit substantially thinner than the rest).

 

The drawing is incorrect and you are forgetting LOS. The shape of the Challenger 1's special armor cavity results in large portions with little weight being marked. The sponsons are not fitted with special armor. The Leopard 2 achieves more LOS at a larger area, which is good when looking to maximize protection, but also means more weight is distributed into the hull armor.

 

The Challenger 1 hull was apparently designed to provide at least 275 mm steel-equivalent protection, but weigh as little as possible, as the CR1 exceeded the weight that the British army was actually comfortable with. Assuming that the protection level sticks close to this figure doesn't seem unreasonable. The hull special armor weighed 1,427 kg, meaning out of the 6,925 kg overall special armor, 5,498 kg (or about as much/a bit more special armor as the Leopard 2 has in hull and turret) of the armor is located within the turret.

 

15 hours ago, Scav said:

Also, again, 325mm if we go by Shir 2 numbers....

 

Which was reduced on CR1 due to different requirements.

 

15 hours ago, Scav said:

Larger area covered, unconfirmed weight, cast base turret and similar LOS to leopard 2 front armour, I don't see how it can be much better.

 

More weight per surface area, speculatively a thicker backplate and armor actually designed to defeat a 125 mm APFSDS... I fail to understand where your problem lies.

 

6 hours ago, Liberator said:

It is strange that the angles are + -25 °, although turret angles have +-30 °. Although perhaps this is due to fact that early data?

 

50° (-25° to +25°) was actual normal for NATO at that time. MBT 80 and M1 Abrams were also focused on a 50° arc, as increasing this arc to 60° would result in to much weight gain.

 

6 hours ago, Molota_477 said:

There are some interesting armor weight data of MBT80 here: 

To against the 430mm KE threat(Original GSR 3572), the turret armor weight —— 6045kg 

As for 480mm KE threat—— 6880kg 

And 540mm KE threat —— 7495kg 

While Challenger only estimated to have 5498kg of armor on the turret. 

 

That is only special armor though. What if the Challenger 1 has a thicker steel shell behind the special armor?

 

[Molota_477]

28 minutes ago, Scav said:

But then the HEAT protection specified in a later document wouldn't be achieved, and "480mm" is again higher than what they settled on for MBT-80 while also not specifying what round it is against.

 

28 minutes ago, Scav said:

That's weird, MBT-80 settled on ~405mm KE requirement and ~850mm CE.

I don't know where it said, can you give some hints?

30 minutes ago, Scav said:

Can you link where you got these weights?

All my data come from MVEE Report 78013 and 78020, their time frame is 1978.

[Scav]

3 hours ago, SH_MM said:

This is again very speculative. First of all, M111 is a lot better than the 105 mm KE/38. According to Krapke, the development of the 105 mm smoothbore gun by Rheinmetall and the corresponding ammunition was halted after an "improved 105 mm round M735" managed to essentially match the performance despite being fired from the rifled M68 gun. It is not mentioned how this round was improved (Better propellant? Prototype with better tungsten alloy composition? M735A1 with DU penetrator?), but West-Germany decided that the smoothbore version wouldn't offer enough growth potential offer the rifled L7A3/M68 to make funding the further development a reasonable investment.

M735 used 18.5g/cc alloys.

 

3 hours ago, SH_MM said:

The Leopardd 2AV hull was specifically designed to meet the German interpretation of the US Army protection requirements for the XM1 tank program.

And according to the US, it didn't perform as well as the XM-1, most likely as a result of the skirts (or lack thereof) and hull protection/amount of hits the armour could take.

I don't think you can deny that the protection levels between hull and turret ended up being different though.

 

3 hours ago, SH_MM said:

Also note that the protocal mentioning several changes made from the transisiton between Leopard 2AV and Leopard 2 mentions that protection has to be provided for the hull only at 900 mm above the ground (meaning the lower front plate is not reaching the same level of protection).

Then there would still be a difference between the highly angled upper glacis and the actual composite, unless the hull was only around 300mm effective, which would be lower than Challenger 1.

 

3 hours ago, SH_MM said:

The Swedish tests of Rheinmetall's 105 mm smoothbore gun are very interesting, but unfortunately they don't tell us anything about the actual performance of the round outside the test conditions and do not contain enough information to make them applicable to other cases. What is the normal propellant charge size used for the 105 mm KE/38? What is the muzzle velocity? What is the velocity loss per 1,000 metres traveled?

Velocity loss from sources appears to be from 75m/s to around 100m/s.

Normal velocity is probably between 1450m/s and 1500m/s, it's what most of these 105 rounds have.

 

3 hours ago, SH_MM said:

Really important factors are not mentioned in the document, so we have to look at other documents and assume that they are based on similar prototypes with similiar performance; but these documents provide rather conflicting - or questionable - data. For example according to tables summarizing the trilateral gun trials (which is based on a British report), the velocity loss for the APFSDS ammunition fired by Rheinmetall's 105 mm smoothbore gun is 100 m/s per kilometre. Yet later data for the 120 mm DM13 APFSDS shows a better velocity retention.

Not really conflicting, just much earlier data, these are prototype rounds after all and not production ones (which probably perform better...)

 

3 hours ago, SH_MM said:

Also note how soft the steel used in the Swedish tests is: 255 HB, while the turret structure of the Leopard 2 was apparently made of HFX-130 steel with a strength of 1,300 N/mm (equivalent mean hardness 383 HB). How much is the protection loss from using such soft steel plates? 10%, 20% or more? Supposedly the Soviets rated the cast armor used on T-55, T-62 and T-72 (hardness 260-280 HB) as 5% to 15% less effective against armor-piercing ammunition than the rolled steel plates utilized for the hulls (hardness ~300-350 HB).

Not denying the actual armour would be better on the leopard 2, just showing that this round really isn't bad and relatively potent as far as early 105 APFSDS goes.

And if this 32mm round is M111 (which it might not be, though it's not unreasonable to think it might be), then atleast in this point in time they were fairly close.

 

Also, wasn't DM13 specifically designed to have improved performance against complex targets?

If so, what would it have comparably better performance to? Some DM13 proto with a monobloc core?

 

3 hours ago, SH_MM said:

No, that would be a very silly thing to do.

I assume that the Challenger 1 was tested against a simulated 125 mm APFSDS round, because it was required to protect against a certain (fictive) 125 mm APFSDS round. The Leopard 2 from 1979 was not required to defeat such a round, as its armor protection requirements were apparently focused on 115 mm APFSDS rounds (NATO being unsure about the existance of the 125 mm gun by the mid-1970s) simulated by the 105 mm KE/38.

So, despite carrying the 120 and using (mostly) the same round as the 105, they wouldn't have tested it against the leo 2?

Seems odd, not that the UK actually had a round that could simulate those estimated 125 rounds either, so not like they could test the armour with it.

 

3 hours ago, SH_MM said:

It is not a vague term and has only been used to describe one specific type of armor (sandwich of an elastic material and steel plates). For other types of armor, there are other terms.

The times I've seen it used they didn't specify what it consisted of, being used along terms such as: "Sonderpanzerung".

Because they didn't specify the times they used it, you cannot know what they mean, hence it's "vague".

 

3 hours ago, SH_MM said:

Space efficiency. T-80BV has ~400 mm steel along the line-of-sight for an armor thickness (LOS) of 587 mm, the T-72AV has ~413 mm steel along the line-of-sight for an armor thickness (LOS) of 573 mm, while the early T-72B had ~453 mm steel along the line-of-sight for an armor thickness (LOS) of 587 mm.

That doesn't explain the lack of textolite, or why they didn't just make the steel plate thicker instead of going more more but thinner plates.

 

3 hours ago, SH_MM said:

Also note that my previous statements were focused on comparing different potential layouts of spaced armor, not spaced armor versus laminated armor utilizing textolites; although the latter seems to be more effective per weight at stopping shaped charge warheads.

Ah, just a misunderstanding then.
I was referring to the lack of textolite and increase in steel plate count with decrease of thickness (not always though).

 

3 hours ago, SH_MM said:

Kinetic energy. At ~1,000 m/s velocity, the tip can travel 60 mm before the shaped charge jet has fully formed and exited the projectile. Sure, at longer distances the muzzle velocity of DM12/M830 will be a bit lower, but the problem will remain.

 

3 hours ago, SH_MM said:

To stop HEAT-FS rounds, a sufficient thick steel plate needs to be placed in front of the ERA, so that the warhead is initiated before the round pases through the explosive reactive sandwich. The box of Kontakt-1 was too thin to set off the fuze, only with Kontakt-5  ERA became sufficient against HEAT-FS rounds.

Would the two layers of explosives not have any effect on this?
I thought that's one of the reasons why they had two layers at different angles.

 

3 hours ago, SH_MM said:

"Last changed" doesn't equal "all values and statements were updated", you can find quite a few examples in declassified British documents where figures weren't updated despite later changes to parts of them.

That's assuming they didn't do their job and that weight wasn't considered important enough to be updated.

 

3 hours ago, SH_MM said:

Aside of that, just look at what you previously wrote:

- Challenger 1 supposedly weighed 59.5 metric tons, but Shir 2 would weigh up to 62 metric tons -> therefore CR1's armor is supposed to be weaker

- Shir 2 was adopted as Challenger 1 "without major modifications"...

 

So where did the excess weight go?

Different transmission and automotive components, supposedly using aluminium roadwheels for instance and the new suspension (hydrogas).

Cutout for the TOGS probably saved a bit as well.

 

3 hours ago, SH_MM said:

Also the Shir 2 was rather dramatically modified before turning into the Challenger 1, e.g. the turret armor was improved as mentioned in British documenets, as I previously posted.

Which I haven't seen anywhere else and could mean a lot of different things.

Without increasing thickness, they'd have to increase weight (didn't seem to happen) or make the inserts substantially better by using higher quality materials (thereby increasing price).

Then it somehow reaches 500mm from around 420mm (assuming protection scales with the LOS thickness)?

 

It's a bigger leap to think that "improved turret armour" means a substantial increase in KE resistance without visual difference or secondary source confirmation, than to assume they got the weight of the tank right on official documentation which was finalised 2 days before the tank got delivered.

The weight was also clearly "filled in" after the document itself was made, which is exactly what you would do if you weren't entirely sure about specifics yet and were waiting for the last moment to fill them in.

They had three months between acceptance of CR1 and delivery of the first tank/last modification of the document.

 

3 hours ago, SH_MM said:

... and then again new protection requirements were made after the Soviet 125 mm gun was recognized as a more capable threat.

You mean the document talking about Challenger I, II, III or the MBT-80?

Because if it's the latter, I didn't see any mention of this before and that would still not prove that CR1 was then required to achieve the same level of protection:

Spoiler

 

Thanks to @Molota_477 we know:

9 hours ago, Molota_477 said:

There are some interesting armor weight data of MBT80 here:

To against the 430mm KE threat(Original GSR 3572), the turret armor weight —— 6045kg

Which means that to achieve 430mm of protection the turret had to be 480mm thick (probably at normal and including turret casting), this is substantially more than the 430mm of CR1 (at normal, confirmed to be with turret casting).

So..... pretty much all secondary sources (this one is fairly well respected) say that MBT-80 was to have superior armour.....

 

3 hours ago, SH_MM said:

The drawing is incorrect and you are forgetting LOS. The shape of the Challenger 1's special armor cavity results in large portions with little weight being marked. The sponsons are not fitted with special armor. The Leopard 2 achieves more LOS at a larger area, which is good when looking to maximize protection, but also means more weight is distributed into the hull armor.

Spoiler

You think they left those hollow?

LOS of the main UFP armour for both is around 630-660mm, with leo 2 going down on the LFP and CR1 also going down starting from the beak til below the numberplate (below that is plain steel).

Still looks like a bigger or perhaps comparable area to me.

 

3 hours ago, SH_MM said:

The Challenger 1 hull was apparently designed to provide at least 275 mm steel-equivalent protection, but weigh as little as possible, as the CR1 exceeded the weight that the British army was actually comfortable with. Assuming that the protection level sticks close to this figure doesn't seem unreasonable. The hull special armor weighed 1,427 kg, meaning out of the 6,925 kg overall special armor, 5,498 kg (or about as much/a bit more special armor as the Leopard 2 has in hull and turret) of the armor is located within the turret.

Still don't know where this number comes from, finding info on CR1 special armour weight is nigh impossible.

Also, leopard 2 most likely used HHA and didn't use a cast turret base.... that alone will make it quite a bit more mass efficient (never seen mention of HHA for CR1, but I have seen mentions of aluminium...).

Why would they downgrade the hull armour from Shir 2 to CR1?

I'd think this would be mentioned somewhere.

 

3 hours ago, SH_MM said:

Which was reduced on CR1 due to different requirements.

It's never specified that it was reduced.

 

3 hours ago, SH_MM said:

More weight per surface area, speculatively a thicker backplate and armor actually designed to defeat a 125 mm APFSDS... I fail to understand where your problem lies.

Again, I didn't see any source for the weight and that thicker backplate is cast, which itself isn't good for thickness efficiency, they didn't even have a 125mm APFSDS (or simulant) of the levels you say it's required to defeat.

 

What we have is:

• doc from 1981 saying T-72 tank rounds can only be stopped above 1000m by CR1 turret, same doc specifies said round as penetrating 480mm of RHA at this range
• UK considering USSR ammo inferior to their own
• later document (unknown date) specifying turret to protect against 105 and 120mm APDS, 125mm APFSDS such as the quoted Russian round....
• Thinner armour than MBT-80 which was required to stop 430mm
• same LOS as leo 2 turret
• higher emphasis on CE protection
• inefficient cast turret base
• lower weight than Shir 2, tank it's based off and whose armour was 325mm on the glacis and uknown value for turret (not designed against APFSDS).
• secondary sources all agreeing CR1 was less armoured than MBT-80 and was "outdated" by  around 1990
• Primary source stating armour was slightly superior to XM-1

 

2 hours ago, Molota_477 said:

I don't know where it said, can you give some hints?

Tank design – a discussion of some of the factors which influence the choice of armour
and gun, DEFE 24/1369

(I don't have this)

https://discovery.nationalarchives.gov.uk/details/r/C11345559

Dates to jan of 1978 to dec of 78

 

2 hours ago, Molota_477 said:

All my data come from MVEE Report 78013 and 78020, their time frame is 1978.

Thanks!
That's from April of 1978 apparently.

 

 

Would be interesting to compare both documents.

Thanks for that other info btw.

 

 

 

edit: SH, if you think they sacrificed hull armour and put everything on the turret, so be it, but there's really about as much proof for that as there is for what I've said.

[Molota_477]

12 minutes ago, Scav said:

Tank design – a discussion of some of the factors which influence the choice of armour
and gun, DEFE 24/1369

(I don't have this)

https://discovery.nationalarchives.gov.uk/details/r/C11345559

Dates to jan of 1978 to dec of 78

Thanks，I 'll try to find.

 

21 minutes ago, Scav said:

That's from April of 1978 apparently.

Yes the 78013 dated on April, and the 78020 dated on June.

[Wiedzmin]

On 5/13/2019 at 6:54 AM, Molota_477 said:

CR1 UFP without cover

 

so they changed from rails to that aluminum( doesn't look like steel)/non metal backing plates like on CR2 ? you sure that is CR1 hull ?

 

 

On 5/13/2019 at 7:12 AM, Molota_477 said:

Interesting that the No.4 array had been mentioned in a report of Chieftain mk5/2, would you mind share the source of this message?  Title of report is ok.

T 225/3237, main problem that there is no detailed info about 5,7(40 and 60 degree cone) and 8(40 and 60 degree cone) inch warheads, what explosive it used, what was the speed of jet etc, thats why real effectivness of all of those "Biscuits" vs real ATGM/RPG not quite clear

 

 

17 hours ago, SH_MM said:

Leopard 2 has been focused on a certain (not specified) frontal arc.

Late requriments for L2 lets say have similar requriments as L3 in terms of KE, 120mm from 1km IIRC(doesn't have doc at the moment), knowing L3 armour array you can propose what L2 array is

[Liberator]

28 minutes ago, Wiedzmin said:

so they changed from rails to that aluminum( doesn't look like steel)/non metal backing plates like on CR2 ? you sure that is CR1 hull ?

perhaps the rails were only on early prototypes? Are you sure that these are non-metal elements?