Scav

15 hours ago, alanch90 said:

I´m 99 percent sure that front hull is NERA  like "NATO armour/T-72B turret". Also i do suspect that it makes a lot of sense if the tank uses "reflective plates" just like T-72B/90 or an upgraded derivative. Some pages ago i did a very rough estimation on potential T-14 armor effectiveness if thats the case (although i was using a LOS thickness estimation that was wrong), i should make another one. On the other hand, its been published that the russians did make investigations regarding NxRA and that may be also what is present in T-14, if thats the case then the armor effectiveness may very high.

About the sides, there is at least one confirmed type of ERA and an unconfirmed type of module. The confirmed on is 4S24, covering the ammo section (thus protecting against Tandem HEAT). The unconfirmed type of modules are those which protect the crew compartment and given the overall thickness my guess is that those may vey well may be Malachit modules just like in the front hull.

Thanks, I remember reading somewhere that the manufacturer actually gave an armour protection figure (900mm vs KE with ERA) and that there was ERA on the front.

Assuming that's correct, then I think it might be reasonable to assume it's Relikt or perhaps an improved version thereof and that without this ERA the protection would range around 600mm.

Certainly doesn't seem unreasonable given the LOS or the armour levels previously achieved on T-90 etc.

 

Still I wasn't able to confirm this rumour so take it with a pinch of salt.

 

I've always wondered why the side looked the way it does, there's three panels that are hinged to each other while the rest isn't....

Those three panels are right next to the crew compartment and I assume those aren't the same as the rest, but why are the front ones not hinged too?
What's the purpose of it?

These front panels are also larger than the rear ones as can be seen by the height difference and they also look a little bit thicker if you ask me, maybe they're NERA and not ERA?

 

The box above the side panels has also intruiged me, it looks very much like the boxes on T-72s etc that are for storing equipment, but the size of them makes me wonder why they would leave such a large gap (relatively speaking) in the coverage of the ERA between the hull and the turret.

There's gotta be a reason for it all, the front panels being NERA sort of makes sense as they would be able to sustain multiple hits, which would potentially increase survivability for the crew, but ERA tends to be more effective for the same volume so......

Do we know if it still uses the "USSR" style of composite like on T-90 and T-72 hulls? 
Or is it more like NATO armour/T-72B turret?

Also, there's ERA on there too, which should be taken into account.

 

Sides don't appear to be too thick apart from the skirts/ERA.

11 minutes ago, SH_MM said:

Ceramic armor was developed and tested already in the 1970s. For example, four layouts of ceramic armor were patented by Blohm & Voss in 1973 (!), yet the Leopard 2AV and first series variant likely used only NERA + spaced steel armor. It would be very odd to see them completely switch to NERA later.

Interesting, any mention of what ceramics would be used?

 

13 minutes ago, SH_MM said:

The arrow appears to be indicating that on the right side of the line the crew area starts, not that the protection extends to that area. The protection value is clearly listed under the caption "BUSTLE".

Ah, I'd figured that the arrow meant the protection applied to the rest of the crew compartment area as well, bit confusing to be honest, connecting the arrow to the bustle section threw me off.

 

17 minutes ago, SH_MM said:

That is from 1980. Some sort of big reveal about Soviet capabilities was discovered by NATO intelligences at some time in 1979-1980.

So right after the UK's assessment.
 

22 hours ago, SH_MM said:

530 mm penetration at built-in stand off distance, up to ~620 mm possible in static tests.

Explains the difference in reported numbers, thanks for the pic.

 

22 hours ago, SH_MM said:

I wouldn't say that protection against shaped charge was likely worse per LOS (given that spaced NERA offers relatively low protection per thickness), but it was clearly worse per weight. The US noted after testing the Leopard 2AV's armor that the XM1's armor was "better" but this would be related to the "differences" in perceived threats.

Yeah, that's probably a better way of measuring it.

It's rather clear that the XM-1 would've been quite different in protection, from what I can tell, the entire turret front and side of the M1 was supposed to protect against this 81mm HHIW, and at perpendicular angles too as the Swedish leak suggests:

I strongly doubt the 2AV's turret side like the drawing from Wiedzmin would protect against that, probably only from a frontal angle around the crew, bustle wouldn't protect against anything but autocannons.

 

22 hours ago, SH_MM said:

Neither can the M1 Abrams at the side of the turret. Only the turret bustle was required to stop a simulated RPG at perpendicular impact angle.

Huh, why'd they do this then:

I assumed that was to indicate that it applied to the entire turret and not just the bustle?

There is less NERA there, but the base armour is also a lot thicker, 101mm thick or so.

Might not be sufficient, but it's probably still better than what the 2AV has.

 

23 hours ago, SH_MM said:

This is not a problem of the Brits, it was shared incorrect estimates from NATO intelligences. T-64 was believed in the mid-1970s to have only a 100 mm thick glacis sloped at 70° and a ~250 mm cast steel turret, i.e. to be armor-wise only a minor upgrade of the T-62.

That's odd, as the US at this time considered T-72 to be better:

Before introduction of M774 (which means pre 1980) and M735 is considered to not be good enough even in a best case scenario and M735 had over 150mm of penetration at 60° at 800m.

That should be considered enough to defeat 100mm at 68° (or 70°).

Original T-64 layout was around 330mm against APDS like M392 and the immunity range was 500m or beyond according to Soviet requirement, M735 is a marked improvement over that round and thus should be capable of dealing with the original layout...

 

It seems like the T-72 in this scenario had it's armour rated at or above 300mm for the hull alone, turret likely being the same if not higher.

Quite a bit closer than the UK estimates, though they could just be using old and outdated ones and the US newer ones.

 

12 hours ago, Militarysta said:

Yes, now I see - the Author must use the same raport. Interesting couse mentioned in this raport parts where more optymistic for Leo 2 the author mentioned in article.

And on second thought - you have right and possible that Britons downgraded  Leo 2 protection. More or less all asumptions in this raport are based on fire trials in 1987 when DM23 was shooted from 200m and HOT CE was fired. And there was simple recognition:  penetrated (+ behind armour effect) / not penetraed and indeed whole protection levels and mass eficency where based only in this recognition and German claims about swicht to cermics.

So the crusial is answer about DM23 and HOT warhed in 1987 capabilities

Does it mention a simulated range for DM23?
Or is the 200m range the range they were also simulating?

If so, that's quite like the diagram of the T-80U turret from the Swedes where they also give a 200m version and a 2000m version.

Was that Swedish diagram actually German in origin? One of my contacts claimed the Germans had conducted some tests on T-80 as well, but I wasn't sure if they just had test results or actually conducted the tests themselves....

 

Thanks for the additional info.

 

12 hours ago, Militarysta said:

propably you have right BUT british sources are now the youngest (ca middle 80's) avaible. Germans archive ar open up to 1979 circa. Many polish historican and armour warfare analyst went to UK  and DE and searcht - mostly in 2WW subjects, but sometimes discovers are suprising.

True, there's actually more UK documentation flying around than German, which I find quite funny.

 

 

52 minutes ago, Militarysta said:

?

Same values.

 

55 minutes ago, Militarysta said:

In case Leopard 2 eacht single hit is describe whit angle and ressult - including behind armour effect... so IMHO it's rather accurate. Despit fact that DM23 and HOT warhed are mentioned in the same document.

I'd love to see pictures or see more detail on that.

 

57 minutes ago, Militarysta said:

There are only two option in sucht way:

a) Swedish and "some" raport whit Leo 2 1987 fire trials is mistaken and erly Leo2A0 protection was mucht higher - acoding to 2AV - exatly 420mm RHA so Britts are wrong couse 1979-1988 and 1988 Leopard 2 have the same mm RHA vs KE and it was up to 420mm RHA. But this source rejected sucht opportunity in three mentioned parts including weight efficency vs KE and CE. 

b) Leopard 2A0 had verry difrent then 2AV armour.

Frankly, I don't trust the Brits when it comes to talking about tank armour of other nations, they've been wrong on many occasions and often downplaying armour of other nation's tanks.

Here we can see the T-64 and T-72 being misjudged by a large amount even if we assume they refer to the hull armour.

T-80 is about right at 350mm even though T-72 and T-64 had practically the same armour at this point.

 

They also criticise certain aspects of tanks like XM1 and leopard 2, despite using that very same aspect or concept in their own "dreamtank" (MBT-80):

Ammo in the back of the turret is frowned upon, yet they were planning to use it in the MBT-80.....

 

There's also the case of CR1's replacement, where people in charge of testing CR2, Leclerc, M1A2 and TVM all favoured the M1A2 or the TVM over the CR2, even going so far as to say they should atleast get the L44 if they opt for CR2.

Politics intervened and they got the CR2 with the L30, because they'd already done the test against M1A2 and TVM they opted not to send a CR2 to compete in the Swedish trials, probably out of fear to see it end last and draw their earlier decision into question.

 

Unless they have actual test results with confirmed threat and armour target, I will take whatever they say about other tanks with a grain of salt.

 

Anyway, I'd love to see more info from either Wiedzmin about this or from you on those firing trials.

55 minutes ago, SH_MM said:

It is not the MBT 80. Three concepts were apparently considered at different times for the Challenger PIP - turretless tank (achieving maximum armor protection), low-profile tank with autoloader ("British T-72") and conventional tank (with the lowest protection level). The drawing shows the "British T-72" concept with 55 metric tons weight, carousel style autoloader, three men crew and transversely mounted powerpack (1,250 to 1,500 hp desired output).

Yeah, that's quite interesting, was the turretless tank supposed to have an autoloader as well?

 

55 minutes ago, SH_MM said:

MBT 80 had central position for driver.

Some drawings have it, some don't, as @David Moyes pointed out, the concept drawings recently posted by Molota have the driver off to the side.

6 hours ago, Militarysta said:

There are detaild Leopard 2 armour test description  - visited by British delegation in 1987.  And there is test description vs DM23 and HOT.  More or less whole document is about Cheftian replacment. The most interesting part about CR1 armour was removed (but armour values in mm RHA are given there) , but there are pure gold about Leo 2, including:

Are these the values quoted by the Haynes CR2 manual?
If so, they didn't specify turret or hull, nor what arc.

Unless they give detailed info on what part achieves what protection, it might not mean the protection was reduced at all.

They could just be using a different way of presenting the same info or even more likely, are just generalising the info and boiling it down to one single RHA value even though the original info does not.

 

I have to point out the similarity between those values (350 and 420mm) and the protection achieved on 50% of the profile for the leopard 2 leaks from Sweden:

Excuse the quick markings, but you can see here that 350mm and 420mm line up pretty well with the 50% area covered mark....

Unfortunately we don't know if Germany gave the UK this slide when they did their trials in the late 80s to early 90s, but considering the similarity between the data and the small timegap between the Swedish and British trials, I think it's quite likely that the middle slide was originally made for the UK and afterwards was repurposed and set over to the Swedes.

That could also explain why it's actually three slides and why the middle one looks slightly darker and is also in English as opposed to the other two being in German.

 

But as you can see, there's various ways in which the information could be interpretted, and seeing how there's absolutely no indication the frontal turret armour was touched or changed in those pictures @SH_MM posted earlier, I don't see why you think they all of a sudden decreased the frontal armour by ~100mm while also keeping the weight the same....

 

The hull was changed and some other small bits were made thinner or lighter by using aluminium, but there's simply no mention of the turret front being changed, so if this diagram from Wiedzmin is indeed talking about 2AV, that is most likely also the armour that ended up on series leopard 2.

 

7 hours ago, Militarysta said:

For me looks like 2AV armour  was downgraded or replaced by other solution in L2A0 - but knowing "hard data" from this british report from 1987 and numering RHA layers in  2AV armour scheme we know that protection vs KE was downgraded in circa 25% (maybe 30)! And propably CE protection was keeped.  Propably @Wiedzmin have right and for cost production or weight resons Germans choose NERA layout in 2A0 too but mucht lighter and simpler. And I have confirmed in sevral sources that in end 1980's Germans swicht from NERA to ceramis whit famous Nera wedges only in KWS. 

What is funny - in end of 1980's

Germans - cermaics in Leo 2 

Soviet - ceramisc in T-80U late and UD

US - propably in HA  and HC (+ NERA in outher layers)

even Polish start to developed CAWA-2 armour

1970's NERA ----> 1985/1990 Ceramisc ----> ??

Regarding ceramics.... the Swedes tested that in the early 90s and they didn't seem impressed:

Quote

The idea was also that Strv 2000 would use a large proportion of ceramics in the protection structure. The fact that the total proportion of ceramics would amount to several tonnes in each tank made one the so-called Protection Ceramics project started up in 1988. For a couple of years, trials were made with many different types of ceramic - Al ₂ O ₃ (alumina), B ₄ C (boron carbide) and TiB ₂ (titanium boride) - but despite a wide participation from Swedish industry, FOA and FMV, it did not get much more than a mediocre reference framework.

http://www.ointres.se/strv_2000.htm

 

So either it was used in conjunction with the already existing armour without replacing large parts, or they were using different ceramics which the Swedes didn't know about.

 

Either way, ceramics don't offer great multi-hit capability and that's something NATO specifically seems to care about quite a bit.

So if they did use it, I highly doubt it's in large quantities or forms the base of the armour.

37 minutes ago, David Moyes said:

A PIP for the Challenger started around 1983.
1987 is when the Chieftain replacement program started. 
The image used for PIP looks like a MBT-80.

Looks quite short, wasn't MBT-80 roughly the same length as CR1?
Driver position matches though.

On 7/14/2019 at 8:07 AM, Willy Brandt said:

@Scav
Why did they want the reduction in weight?

And how does the MILAN and 105 APFSDS compare to soviet munitions?

I.e against which soviet threats was it protected against?

Can you post the full documents or the source for those?

I don't have the full document unfortunately, just these bits that others have posted before:

These are all the bits I've found on the web, not sure if others have more, you can probably ask @Wiedzmin for those.

 

Milan depends on the source, pretty sure I've seen UK reports saying 530 or 580mm, I'll look for that in the meantime.

 

Weight reduction is fairly simple, as sent over to the US, leopard 2 did not comply with the maximum weight set forth by the agreement between the US and Germany, this IMO isn't a big deal considering the leopard 2 was using heavier tracks than the XM1 (which ended up using very similar ones on the M1A1) and it was using a larger gun.

Still, Germany seemed to still think it was too much and opted to optimise and rearrange some things.

 

105mm APFSDS is some proto version of DM13, SP15 had some stuff on it: https://fromtheswedisharchives.wordpress.com/2019/01/03/rheinmetall-105-cm-smoothbore-performance/

Seems to largely compare to a beefed up 3BM9 if you ask me (performance wise), though design looks more like 3BM42.

 

On 7/14/2019 at 9:19 AM, Militarysta said:

Well now looks that Germans downgrade KE protection between 1976-1978 to keep weight level whit the same SC protection.

It's interesting couse there are doc. showne that erly Leopard 2 had 350mm vs monoblock WHA KE and 700mm vs SC but considering those plans (5.III.1976) we have on projectile path no less then 428mm RHA and no less then 4 NERA bulging plates.

 

Looks like 2A0 was seriously downgraded in this part (KE) to save weight.

Who says it was?

It seems more likely to me that the graph we got from the Swedish leaks wasn't just talking about frontal armour protection but the entire profile instead, which would ofcourse lower the overal protection quite a bit.

From the things I've found, nothing indicates a loss of protection for the turret, nor hull (though the hull isn't specified to remain the same, just that it still complies with requirements).

 

On 7/14/2019 at 11:00 AM, SH_MM said:

I am also confused by the high amount of steel along the line of sight. Assuming the bulging plates are also made of steel (rather than some type of light metal alloy such as aluminium), that's 450 mm steel at the turret front cheeks (I am assuming that the center portion does not feature Beulblech add-ons, given that they aren't shown in the blueprints).

That is valid for the minimum LOS thickness of the turret front, i.e. at an angle of 35°. The LOS from the front is ~22 per cent larger, which would lead to more than 540 mm steel along the LOS - even if the armor was made of pure RHA without any additional layering effects, the protection  level would be on the same level as the MBT 80 with a combat weight of nearly 68 metric tons!

To be fair, it uses vastly more steel and overal higher thickness than the plates inside the arrays of M1 or Shir 2/protos, while the front and backplate aren't quite as thick.

Which pretty much confirms to me that unlike with "normal" chobham, the actual "NERA" sandwiches (or in this case, mostly just spaced steel plates with a small liner/bulging plate on the back) are meant to largely affect KE protection, as they are not only thicker, but mostly made of steel instead of very thin layers of steel + thicker rubber/plastics.

 

Likewise, it explains why the HEAT protection wasn't as good per LOS as on the M1's turret for instance.

It does seem like there's a lot of steel though.... more than I expected (I think around 428mm LOS worth).

 

On 7/14/2019 at 11:00 AM, SH_MM said:

That also would explain the change in minimum LOS at the turret front from 710 mm to only ~680 mm (rough estimate based on the horizontal slope measurements done on a drawing).

Hang on, because I think there might be some confusion here, @Militarysta provided us with excellent pictures pretty much proving that the LOS from the front is 860mm without question, on most drawings and pictures I've found the angle of the cheeks wouldn't be enough to reach 860mm if we assumed a perpendicular 680mm LOS.

For reference, the angles I've measured seem to hover around 35-37° , if we assume 36° (bit of an odd number IMO), for 860mm LOS you'd need around 696mm base LOS.

If we take 35° this would increase to 704mm base LOS.

IMO, that seems closer than 680mm.

 

So, was there really a change in LOS?
Comparing pictures, I can't tell and it would seem rather odd to change it by such an insignificant number.

 

On 7/14/2019 at 11:00 AM, SH_MM said:

An alternative interpretation to the "armor protection remaining unchanged" could be related to the reference threat: maybe the new armor - despite providing less overall protection - could stop the reference threats at the same range & distance, as the heavier armor package shown in the drawing, which was "overkill".

As in a more efficient design or perhaps higher quality steel?

That's quite likely.

 

On 7/14/2019 at 11:00 AM, SH_MM said:

The drawing might be wrong in some way?

I prefer to see the original, though I understand if Wiedzmin can't give us that.

Would be a real shame though, I'd love to see that.

 

On 7/14/2019 at 11:00 AM, SH_MM said:

but the side armor reaches only a ratio of 0.262 to 1), so I can only assume that it is higher than 360 mm.

The side seems to be quite thin honestly, around 120mm of steel for ~320mm of LOS.

Probably also why the US complained about unbalanced protection, the side probably can't stop an RPG-7 fired perpendicular, though it might from a frontal angle.

 

On 7/14/2019 at 11:00 AM, SH_MM said:

The Leopard 2AV weighed much more, because designers didn't focus that much on the weight goal. I.e. in 1976 it was reported by an US General during a hearing at the Congress that the Leopard 2 weight more than 60 metric tons.

I'm pretty sure they were using imperial tons, metric tonnes would be written differently and the XM1's weight was also listed higher than what it is in metric.

 

On 7/15/2019 at 7:00 PM, SH_MM said:

Regarding weight reduction:

Welp, guess I should've scrolled down first before writing.

 

Thanks for those other pics tho, I couldn't find them anymore.

1 hour ago, Sovngard said:

What were the protection requirements again ?

 

105 mm APFSDS fired from the German smoothbore gun and the MILAN 1 ATGM ?

2AV

 

On 5/24/2019 at 1:20 PM, HAKI2019 said:

Do you have source that the turnnion is solid？My friend think it is empty like leopard 1.

Swedish shooting table for leopard 2 lists gun parts and has the trunnion/gun cradle listed at 595kg.
Official Rheinmetall brochure for the L44 from 1982 has these weights:

630kg for mantlet, 1905kg for barrel, 1110kg for breech assembly (inc gun cradle).

Volume of gun cradle x density of steel gives very similar numbers as reported by the Swedes and indicates it's not hollow.

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:

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.

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.

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.

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°:

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).

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.*

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:

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:

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:

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:

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)

On 5/5/2019 at 6:45 PM, LoooSeR said:

That is interesting part.

Smart propellant system?
Somehow making sure the round gets the proper velocity by adjusting something in the propellant, or maybe even some primitive guidance method to limit effect of wind?

There's a few things that it might be, some make more sense than others, I think a programmed seperation action for a part of the penetrator makes the most sense.

 

On 5/7/2019 at 3:29 PM, BkktMkkt said:

body/core/penetrator - 226214,6547mm³ 

But i think diam should be 32 mm

Penetrator mass should be 4.23 kg
Density of UZnNi alloy is unknown, but in some sources it is 18600 (95%U)

Thanks, there's a lot of conflicting data on this round, but this volume makes sense and adds up to the possible weight.

One thing that never lines up is the penetration though, often claimed to be 430mm at 2000m 0°, but this doesn't seem possible with the dimensions of the round and velocity at 2000m.

10 minutes ago, Wiedzmin said:

no, there is many pages, part - front with add-on armour, part about hull side which is 80mm thick and have side screens far from it (spaced at distance of track etc), part about comparing with rh105 etc...

Ah okay, is there anything on the frontal add-on armour?

 

11 minutes ago, Wiedzmin said:

i think you can find some reports about M392 APDS IIRC which was tested on 240 bhn plate in US, usual practice at the time 220-250bhn, and many others in archives 

For US maybe, but I think UK mostly used 260-300BNH.

 

On 5/1/2019 at 9:22 PM, VertigoEx said:

A LOS of ~760mm isn't that bad..

True, definitely isn't bad, but that is the maximum and it hasn't been upgraded since (that we can tell).

 

5 hours ago, Wiedzmin said:

it's describes only as auxilary armour, distance of spacing showed only for target represent tank side, quality of german plates similar to soviets tank armour(i think a talked about it earlier), not US/UK junk test plates (220-240bhn)

So, we're talking about auxiliary armour like a Pz 4 H? 
A thin steel plate put on brackets outside the tracks of the vehicle?
If that's the case, it's probably about ~500mm away from the main side plate (width of thet tracks are the minimum) at normal, and at 70° that would be about 1460mm.....
 

That's quite a large space, it doesn't really surprise me that the round has issues with such a large gap, it kind of reminds me of this:

Bottom row is quite similar, 65° and 1550mm space gap between a 10mm frontplate and 70mm rearplate, this arrangement was 18.3% more mass efficient than an 80mm plate.

Frankly, that doesn't make DM13 look bad, not when you realise it's essentially a round from 1974....

I think it would do better against the actual frontal armour array as it seems the first segment was "wasted" on the thin 10mm plate....

 

Also, junk US/UK test plates?
Where do you get this from?
I know the M60s had very soft armour etc, but I didn't think they tested with equally soft steel, same for the UK.

 

 

2 hours ago, BkktMkkt said:

Some my models

Interesting, never heard of BM22M before.

Those are some nice models, if they are to scale, could you post the volume and dimensions of BM32?

To clarify the hull armour layout on M1(A1):

The plate under the tank that covers the special armour cavity is ~23" long (26.5"-3.5"), with the exterior LFP plate being 1.25" thick and set at roughly 39°, the interior plate is 4" thick and at an unknown angle (I presume the same as the exterior plate).

Exact measurement is hard to see in the picture, and it wasn't easy to get them, so big thanks to my friend that went back and crawled under it

 

As the plate in the picture is also at an angle ~8°, we can try to add these values together to get the rough LOS thickness: 1.25" @ 39° + 23" @ 8° + 4" @ 39° = ~30" or about 762mm.

Bit of an odd number (the raw thickness) as it isn't nice and round, guessing the actual length of that bottom plate is 22.75", which would make the raw thickness 28".

None of the angles are for certain as it wasn't measured, but the difference would be rather small.

23 hours ago, VertigoEx said:

I found this and reposted this on the SB forum.

 

Interested in what others here think..

 

More insight into assumed threats to early 1980s armor. If it is a threat to a IFV it is a threat to tanks that fight with them.

 

So the USA experimented with armor arrays similar to the Xm-1 that could defeat 115mm DU ammo across the frontal arc. So at some point the USA was testing BRL-1 or BRL-1 like armor arrays against not use W, but DU ammo. 

Interesting, perhaps the substantial % of additional weight going to the extra 6° of frontal arc protection is due to the much larger surface area on the side of the vehicle rather than the small frontal area?

 

23 hours ago, VertigoEx said:

Perhaps this is what evolved into BRL-2, or a reformulated version of BRL-1.

I've only ever seen BRL-2 mentioned as being "improved armor" when talking about IPM1 vs M1, it's never mentioned how, so it seemed logical it was just the increase in thickness they were referring to....

Either way, do we know what they were using as simulant for this 115mm DU round? (or where we can find this paper?)

 

23 hours ago, VertigoEx said:

IIRC Tankograd has evidence that suggests that  BRL-1 on the M1 uses titanium alloys with or in place of steel in the NERA array.  That would increase the ME, but not the TE against KE rounds no?

Yeah, but you'd also need a higher thickness of the plates to get the same effect, unless the first steel used was quite soft and the new alloy was very good...

On 4/21/2019 at 6:33 PM, Mighty_Zuk said:

Externally, I haven't really paid much attention to it.

But the difference in armor construction is visible here:

Many thanks

 

On 4/21/2019 at 10:07 PM, Sovngard said:

IIRC, the Merkava Mk. 4A has a new commander panoramic sight and lacks of loader hatch.

Oh right, I read something somewhere about the loader's hatch being deleted....

16 hours ago, Mighty_Zuk said:

Fuel tanks in any tank can catch fire. That's not unique to the Merkava. In the Merkava it may fry the engine. In another tank it could fry the driver.

IIRC diesel isn't so bad, unless the warheads (HEAT rounds, I don't know about APFSDS) use aluminium liners.

 

16 hours ago, Mighty_Zuk said:

That was a problem with the Merkava 4A, but not the Mark 4B and subsequent variants.

Is there a way to visually differentiate them from each other?

 

16 hours ago, Mighty_Zuk said:

L/55 is better if you only take raw penetration into account. But that is not the only consideration. With urban combat growing in frequency, shorter barrels still show some clear advantages. An L/55 is a whole 1,320mm longer than the L/44, and that makes it hard to traverse in narrow city streets. That is, when considering that any tank with the L/44 is already pretty bulky for streets. The Merkava's turret was built in a way that allows for substantial growth in firepower - up to 140mm. Accepting an L/55 gun is a no biggie. But there is no operational need for such a gun, and it's possible the IDF will skip right to the 130mm or whatever the next gun may be.

Germany actually still has some 2A5s in storage according to one of my friends (ex 2A6M loader) for urban warfare.

Or they could've been 2A6s but with the L44, I don't quite remember...

On 4/16/2019 at 11:53 PM, SH_MM said:

This is your interpretation of the slide. The slide just speaks about the "German model", which at the time probably was the version that Germany was planning to field. It doesn't say anywhere that the German model is a vehicle from the eight batch, that is something that you (falsely) concluded by assuming that the "German model" refers to the TVMs. That Germany at the time when the documents were transfered to Sweden (i.e. 1990-1991) was planning to keep a larger tank fleet - all upgraded to a similar standard.

And the version Germany was planning to field was...... TVM.

 

On 4/16/2019 at 11:53 PM, SH_MM said:

This is not reported, but Hilmes wrote that the poor protection in relation to the other offers was one of the factors for the improved armor arrays of the later Leopard 2A4. Don't forget that the Brits concluded that the turret armor of the Leopard 2 offers less protection against APFSDS than the Chieftain Mk. 10's Stillbrew armor package.

Yeah, and it's probably not entirely correct as they were using cast armour for both the base and the add-on, add the rubber to this and they reached 480-540mm LOS.

If going by LOS, sure it's better, but because both parts were cast and the rubber seems to be included in the overal thickness, the actual protection would be substantially lower, I don't think it would be much better than leo 2's turret.

(they also get to that LOS through angle, which is less effective than vertical armour per LOS against long rods)

 

On 4/16/2019 at 11:53 PM, SH_MM said:

You are assuming that the British military was given the same slides (or very similar ones) as Sweden (and that the slide shown in R. Lindström's presentation is the only one detailing the armor protection of the Leopard 2), that's quite a lot of assumptions...

Why wouldn't they?

The part about leopard 2 "improved" probably wasn't added yet, but I'm sure they gave the info on the other versions somehow, why make a new graph for every country you're planning on selling the tank to?

It's not an unreasonable assumption.

 

On 4/16/2019 at 11:53 PM, SH_MM said:

I don't think the British assessment was wrong, nor that the 350 mm protection cited by Taylor's book are incorrect - it seems that Mr. Taylor just didn't specify the area/arc that is protected. The hull armor of the Leopard 2 (and with that also the minimum overall frontal protection) offers circa 350 mm steel equivalent protection according the Swedish leaks. The turret armor likely provides a minimum of 350 mm steel equivalent protection along the frontal arc. Both two possibile and more reasonable explanations than "the Brits misinterpretting the slides" - specifically considering that they were always focused on protection along the frontal arc, rather than protection only from heads-on.

If it's 350mm for the frontal arc, then it can only be talking about the frontal armour, not the sides.

And 350mm seems too high for the hull (from the front).

 

On 4/16/2019 at 11:53 PM, SH_MM said:

Which given that even Rheinmetall's 105 mm smoothbore gun firing a rather primitive APFSDS round (by modern standards) could defeat similarly sloped steel plates of similiar thickness shows that it wasn't a terrible idea not to rely on sloped armor. HEAT rounds depend on trajectory and fuze (Obus G for example comes really close to defeat the sloped glacis plate of the Abrams) also should be kept in mind.

Perhaps, but one could just add 5-10mm and substantially increase protection, or use a NERA style sandwich....

Just seems a bit too rushed, more testing could've shown highly angled plates aren't a terrible idea....

 

On 4/16/2019 at 11:53 PM, SH_MM said:

Using old tanks (turrets and hulls) without replacing the turret armor inserts. Sort of like upgrading the Leopard 1A1A1 to the Leopard 1A5 rather than the better Leopard 1A3 & 1A4, because it was cheaper and more such tanks were available.

Wasn't there an issue with weight for the hulls?

Something about making sure the hulls could handle any future upgrades....

On 4/16/2019 at 11:41 PM, SH_MM said:

The external shape is irrelevant and doesn't tell us anything abou the type of armor utilized.

I wouldn't say that, in T-72B they could mount it in any way they wanted due to the inconsistency of the cast turret cavity, but  with box like cavities you could make all internal plates the same dimensions and simplify logistics somewhat, would also make it theoretically easier to mount and dismount the plates as they would be individually acessible.

If they were angled (substantially) on the inside I would expect higher (or similar) CE protection as the LOS thickness is greater than M1 yet it somehow has less....

Don't know for sure, but it's a possibility either way and I doubt they're highly angled, atleast in the turret.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

There is not a lot of ways to move steel plates effectively. As West-Germany had access to NERA as proven by several sources (Held's patents, research at ISL, cooperation with UK, etc.), it certainly would have chosen instead of some janky, less effective system only ever used on one tank. Shock-absorbers itself are not enough effective enough to move steel plates fast enough to affect the penetration of shaped charge warheads in any noteworthy degree.

If it reached their requirement for CE protection and was more effective against KE then I don't see why they wouldn't choose it, but I get your point, likely the real way the armour looks is somewhere in-between.

Just don't call it Chobham or say it's a derivative thereof, evidently they had their own armour designs prior to the cooperation between them and the UK, completely ditching their old research doesn't seem likely.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

allow to use steel alloys with high hardness, which are unsuitable for welding (in case of the rubber-wrapped armor plates installed on Leopard 1A1A1 and Jaguar)

Yes, and this is why I think they used this kind of system, it allows them to use HHA plates in the arrays, enhancing KE protection.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

You seem to pretend that the Leopard 2's armor was not focused on protecting against shaped charges, while the MBTs made in the US and UK weren't meant to protect against KE at all. That's not quite right.

 

The armor protection requirements for the Leopard 2 against kinetic energy penetrators were just slightly higher, while the protection requirements against shaped charges were just slightly lower than those of the Abrams.

I didn't say that, but I'll rephrase some of my words:

The emphasis seemed to be on higher KE protection relative to CE protection when compared with other MBTs like M1.

CE requirement for M1: 680mm penetrating SC for only 740mm LOS (0.92 ratio)

CE requirement for Leo 2: 580mm penetrating SC for ~860mm LOS (0.67 ratio)

The M1s requirement was 36% more thickness efficiency against CE than leo 2, that isn't "slightly" more.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The protection requirements for the Challenger 1 were higher against both KE penetrators and shaped charges.

Is it really though?

CR1 was rated for T-72 tank rounds at 1000m, whereas Leo 2 was rated for T-72 tank rounds at 1500m, both on the turret.

Depending on the simulant used, either could be a "higher" requirement.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

Why you want to claim that the Leopard 2 would use a completely different (and non-existant) type of armor just because it has slightly different armor requirements than the M1 Abrams is beyond my understanding. If anything one could assume that the NERA plates are less in number (and more steel plates are used) or - as suggested by the Russian book citing a Soviet intelligence report - that the NERA plates have slightly thicker front plates for improved protection against APFSDS rounds. I also fail to understand why we are having this discussion, given that German authors describe the armor as Beulblechpanzerung (i.e. NERA).

It's not completely different, it probably uses some of the same elements, I just don't think it's a derivative.

Yes, authors describe it as such, same way they did back when everyone thought these tanks used lots of ceramics/plastics/steel in solid arrays, which led to estimates like Paul Lakowski's.....

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The Leopard 2's heavy ballistic skirts are still NERA.

Are they?
Even close up pictures don't tell much about what they are made of, the only things we know is that they're not heavy enough to be mostly steel and that they seem to have a rather big space in the middle.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

Likewise the protection of the turret bustle doesn't say anything about the type of armor utilized on the rest of the tank, as it was just carried over from previous designs and there wasn't a requirement for shaped charge protection in this area. That's like saying that the fact that the M1 Abrams' rear section of the hull has non-ballistic skirts made of 

"Made of...."?

It's an indication that they still think spaced armour is useful, meaning it's still a relevant design choice.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The "Russian" (Soviet) spaced armor arrays are a trade-off between APFSDS and shaped charge protections, available manufacturing techniques, available space for the frontal hull armor array and costs. The fact that the turrets of the tanks made with such hull armor arrays always utilized other types of (more effective) armor says a lot about how "well" liked the spaced hull armor arrangements were.

Pretty sure that they used different armour on the turret for manufacturing reasons, hence why they went for welded turrets with T-90A.....(when they realised cast turrets simply have too many weaknesses).

Yet they are still using the same kind of hull armour arrays....

 

On 4/16/2019 at 11:41 PM, SH_MM said:

Add to this that the existence of Kontakt-1 ERA lead to a possible reduction in the amount of shaped charge protection that the base armor was required to deliver and you got a situation absolutely not comparable to the Leopard 2.

Their armour arrays were quite good against KE despite "only" using spaced armour, it's very likely that Germany noticed the higher efficiency of spaced steel arrays too.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The thin steel plates also become quite thick when accounting for slope, but such a high slope angle would be rather impractical in the Leopard 2's turret.

T-72AV has 60-15-15-15-15-15-15-15-50, while the first and last plate become quite thick, the intermediate ones only get to around 30-45mm.... this seems to be an optimal thickness.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The Leopard 1A3 used thinner steel plates, because it was designed to protect against 100 mm full-caliber AP ammo at most. To conclude that the Leopard 2 would utilize equally thin steel plates because of that doesn't seem very reasonable. 

Not because of that.

But because this thickness range seems optimal against sub caliber shells too....

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The Leopared 2K was the direct predecessor of the Leopard 2 T14 Mod. and with that of the Leopard 2AV and Leopard 2 series production variant.

Leopard 2K heavily utilised angles and spaced armour to obtain it's protection, it only had two spaced layers too....

Pretty much the opposite of 2AV.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The Soviet armor arrays didn't really get more mass efficient, most oof the protection is gained by increasing the amount of steel within the array, from 110 mm @ 68° to 170 mm @ 68°.

Yes they did, they got substantially better over time, not just through higher steel thickness.

I recommend you read this blog on the matter: https://thesovietarmourblog.blogspot.com/2017/12/t-72-part-2-protection-good-indication.html#ural

(you might already have)

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The Challenger 1 features improved turret armor over the Shir 2.

Despite weighing less and having the same armour thickness?
Doubful, if anything this would be a minor change in steel type, yet no sources specify the steels used as being special anyway...

Weight of Shir 2: 60-62t

Weight of CR1 (Mk1): 59.5t

(Also note that they say the armour protection is slightly superior to M1)

 

So..... what is slightly higher than 350mm? 500? I don't think so, and neither did you:

Quote

The Challenger 1 has enough armor to stop a 125 mm APFSDS at about 1,000 metres distance. Given that the British estimated a penetration performance of 475 mm steel armor at 0 metres for a 125 mm tungsten-cored APFSDS round, it seems likely that the Challenger 1 has 400-450 mm protection vs KE; this also would match the statement that the Challenger 1 has protection roughly equal to a T-64BV, T-72AV or T-80BV tank.

The Challenger 2 design - not necessarily identical to the production model - at some point of time was to have improved hull armor; there is no mention of upgraded turret armor (at that time).

That leads to:

• XM1 Abrams - resists 115 mm APFSDS at 800 - 1,200 metres (official requirement), penetrated by 125 mm APFSDS even at 4,000 metres (British claims)
• Leopard 2 - turret resists 115 mm APFSDS at 1,000 metres & 125 mm APFSDS at 1,500 metres (Swiss estimates)
• Challenger 1 - turret resists 125 mm APFSDS at 1,000 metres, hull weaker
• Challenger 2 - turret and hull resist 125 mm APFSDS at 1,000 metres (design specifications)
• Chieftain with Stillbrew - turret resists 105 mm APFSDS point blank and 120 mm APFSDS at 1,000 metres

Quote

Well, this is very interesting and also would explain why the British FVRDE assumed that the Chieftain with add-on armor was better protected than the Leopard 2 at the turret front.

However there seem to be some questionable statements:

• the author states that the the "bulge" created by the mantletless turret design has a thickness of 500 mm. This seems to be only the case when directly hitting the edges; it has been stated by other sources that the thickness is only about 300 mm.
• the author ignores the differences in armor protection provided by cast steel and rolled armor steel.  According to British sources, the hardness of the cast steel was only 260 to 280 BHN, which is the same as Soviet cast steel. The Soviets found that ~260-280 BHN cast steel offered between 5 to 15% less protection than rolled steel with a hardness of 350 BHN (as used for the hulls of T-54, T-55, T-62 and later tanks).
• the glacis plate is not effectively 388 mm thick; maybe it is a type and was meant to be 288 mm, which be roughly maximum protection level of the hull front; however it seems more likley that the author just copied the false value from Wikipedia. Measurements on the real tank with an ultra-sonic probe have shown a hull armor thickness ranging from 80 to 89 mm, which would be 259 to 288 mm along the line of sight. The British requirement as found in declassified documents asked for 120 mm at 60° (240 mm LOS); ~84 mm at 72° was believed to provide equivalent protection.

As for the Challenger 1's armor: 500 mm steel-equivalent protection might be possible, given the date of introduction and its huge weight, but it certainly is not set in stone. Confirmed is that the Shir (Iran) 2, which was used to develop the Challenger 1 tank, had a protection level of 325 mm along the 30° frontal arc (?) in 1978. Given the power-to-weight ratio listed in the British documents, the Shir (Iran) 2 tank weighed 63 to 64 metric tons, just as much as the Challenger 1. In so far the British engineers would have needed to completely redesign the armor array to reach the desired level of protection. In 1978, a protection level of 435 mm vs KE (as achieved on the MBT-80) was considered to be "enough". Originally the Shir (Iran) 2 was to be delivered in 1979 and 1980; but the deal was canceled with the Iranian revolution of 1979. The decision to not continue the development of the MBT-80 was made in July of 1980, the first Challenger 1 pre-series vehicles were delivered in 1982; so if the armor was massively redesign, it must have been done in a rather short period of time... so it remains questionable how much changes were made.

CR1 uses a cast base turret, probably plain RHA as front plate and most probably not much more advanced than what the Shir 2 had.....

 

The armour could've been "improved" in various ways, better against several hits, slightly better coverage on the internal plates, side armour might've been "adjusted"....

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The fact that one document doesn't specifically mention 105 and 120 mm APFSDS rounds shouldn't be a reason to draw any conclusions (for example even the Shir 2 would have resisted the 105 mm APFSDS rounds avialable at the time the document was published).

105mm APFSDS rounds in 1978? Sure, but not 120mm APFSDS rounds in 1980.

 

And it specifically mentions those for the Vickers.

On 4/16/2019 at 11:41 PM, SH_MM said:

Note that the Vickers Mk. 7 with thinner and lighter armor is protected against "APDS and APFSDS up to 120 mm calibre" according to the same page of the document...

Thinner and lighter? Where did you see that?
It's a newer tank, unlike Shir 2 CR1.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

Is the phrasing indicating that Soviet APFSDS ammo can be resisted intentional?

Yes, I've asked multiple people and they all drew the same conclusion.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

Does the mention of resistance against 125 mm APFSDS round make talking about 105/120 mm APFSDS rounds irrelevant (which isn't that unlikely given that British estimates placed up-coming 125 mm APFSDS rounds ahead of 120 mm L23 prototypes in terms of anti-armor performance).

Then why mention 105/120mm APDS?
That's even less relevant.

More on that in a sec.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

According to the Haynes book, the Chieftain's Stillbrew armor was tested against a 120 mm APFSDS fired by another Chieftain - i.e. a developmental variant of the L23 APFSDS. It seems likely that the same round could have been used to test the armor of the Challenger 1. The Bundeswehr utilized a in-development APFSDS round fired from the 105 mm smoothbore gun to simulate Soviet 115 mm APFSDS rounds; assuming that the UK used prototypes of the 120 mm L23 APFSDS to simulate Soviet APFSDS rounds.

The same book also clearly mentions the UK considers USSR rounds inferior to their own.

So, if L23 (penetration of 480mm PB at 69.5°) was "only" resisted at 1000m, then why did they think the armour had a decent chance to stop the future 125mm APFSDS?

Despite said penetrator penetrating more armour than L23 even at vertical (they use this for the previously mentioned 125s).....

 

So, either they considered USSR ammo inferior (probably at angles) or they assumed 2000m+ or they didn't understand that long rods penetrate more LOS armour when the angle goes up.....

In any of those cases, it's wishful thinking on their part.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The British estimates (or rather estimates made in all NATO countries) regarding the capabilties of Soviet weaponry drastically changed over the years. In 1980, they predicted future Soviet APFSDS rounds to reach a penetration of 660 mm steel armor at 2 kilometres and Soviet ATGMs to penetrated 1,000 to 1,300 mm steel by 1995 - very reasonable estimations. Earlier estimates done during the end stages of the MBT80 development saw Soviet APFSDS reach pentration levels of more than 500 mm at closer ranges - again very reasonable estimates. The poor accuracy of early 1970s estimates isn't that relevant for a 1980s tank project.

At what angle though?

Clearly they considered USSR ammo inferior or equal to APDS back in the 70s, and in the 80s they seem to consider it inferior to their APFSDS.

In what way, I don't know, but there's more to it than: USSR APFSDS = NATO APFSDS.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

The Leopard 2 could resist "125 mm APFSDS rounds at 1,500 m" according to Krapke, yet a DM33 round will result in a destroyed Leopard 2A4 at ranges closer than 2,200 metres in Polish practices... the same values are used for 3BM-42.

Both of those rounds are from 1987 and substantially more advanced, which is why it's completely reasonable to assume that less advanced ammo would have a harder time with the same armour array.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

.. and this conclusion is supported by no evidence.

Optimised against APDS, LRPs are substantially better against composites than APDS, CR1 is mostly Shir 2, thus, unless the armour changed drastically, CR1s armour would be less effective against LRPs than against APDS.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

This is your assumption that the "Challenger II" concept would be equal to the Challenger 1 Mk. 2. That is however pure speculation without any evidence supporting it. The Challenger II and Challenger III concepts seem to be independent from the later development of the Challenger 1.

I didn't say that I believed it, quite the contrary, this shows that the document is either looking at the future (it is called "Post 1995 tank research" or something along those lines...) or going very hypothetical.

Challenger 2 apparently wasn't even considered or started until 1987, 6 years after this document was finalised.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

Because the armor has weakspots and not all surfaces can be covered by equal amounts of armor? The Leopard 2 from 1979 also has 350 mm (or more) vs KE on only 50% of its surface. That's pretty normal and also explains how small the protection differences compared to the Chieftain appear to be.

Couple of problems:

• Probability of hit is also calculated, as can be seen by Chieftain having a 64% chance of being knocked out at 2000m despite the ammo being used overmatching the armour on it by a large margin
• This is beyond the range at which the round used achieves 480mm of penetration, so this means that to reach 50% probability of kill with this round, the tank would need to have a minimum of 50% of it's frontal area be a weakspot

When taking that all into account, it means that despite an alledged "500mm RHAe on hull and turret" (double that of Chieftain and more than enough to stop this round) and the reduced probability of hit at this range, it still has a 50% chance of being knocked out??

Don't tell me that 50% (when taking probability of hit into account, way more) of the frontal surface is weakspot....

 

On 4/16/2019 at 11:41 PM, SH_MM said:

Challenger 1 special armor weight is ~6.2 tonnes, while having a rather thick steel back plate. Leopard 2's special armor weight is ~5.4 tonnes with a thinner back plate. Why do you believe that the Challenger 1 would not manage to reach a better protection level than the Leopard 2 from 1979?

Where did you get the weight for CR1 from? Haven't found any good sources for that.

CR1's armour layout is not very efficient, it protects the sponsons of the hull, it doesn't use highly angled plates for a decent surface area to protect the tank (they didn't like this) and the total surface area of the tank that is protected by composite is probably a lot higher.

The front of the turret is wider, the front of the hull is higher, it has more frontal weakspots....

 

Is that special armour weight based off the 62t weight or the 59.5t weight?

 

So, the armour is spread over a larger area and uses angles more to obtain higher LOS.

Speaking of which, the hull is about the same LOS thickness (on the UFP), LFP is massively thinner, turret front is about the same and the turret side is reasonably close too.

If leopard 2 reaches ~430mm KE and 650-700mm CE, how would CR1 reach 500mm KE and 750mm+ CE?

 

It doesn't add up.

 

On 4/16/2019 at 11:41 PM, SH_MM said:

Chieftain with Stillbrew can only be penetrated by the RPG-7 when hitting the weakened area of the gun mount, the turret ring or the roof/hatches.

Challenger 1 can only be penetrated by the RPG-7 when hitting the weakened area of the gun mount, the turret ring or the roof/hatches

Again, it doesn't add up:

If this is Chieftain stillbrew, how come the difference between 480mm threat and 630mm threat is only 1% when Hull down stationary?

Surely the stillbrew package covers more than 1% of the surface area of the turret.....

 

Furthermore, there's a 70% chance to kill Chieftain when fully exposed stationary at 100m, seeing how those "weakspots" definitely don't make up 70% of the surface area, we can conclude this is probably an RPG-7 that has enough penetration to penetrate pretty much any spot on the Chieftain, thus the 70% is due to probability of hit more than armour protection (as evidenced by the probility dropping off severely at longer ranges).

So, from a base probability of hit of around 70%, it drops to 44% when hull down, clearly even if it is a stillbrew Chieftain, those weakspots wouldn't make up more than 44% of the frontal area.....

 

Let's look at those weakspots to be sure:

• turret ring, around 1-3% of frontal area
• gun mount, around 10% of frontal area
• hatches..... can you even consider this a weakspot that leads to a "kill"? If you do, less than 5%.

I don't see how those would add up to around 44% of the frontal area on either Chieftain or Challenger.

 

See how it's just weird?

 

 

19 hours ago, Wiedzmin said:

100mm/70deg - 3057meters

15mm-100mm/70deg - 1250-1290 meters

 

so "good against spaced armour" not good enough, but maybe better than nothing...

Does it specify the airgap size?

That's a nice picture though.

 

Edit: It's also not 100mm/70° at 3057m but 3057m more than the reinforced array, so over 4000m.
That's not bad at all, given the high angle and the fact this is essentially their first APFSDS....(own development)