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10 hours ago, Wiedzmin said:

ZXEorq3aMzI.jpg

 

100mm/70deg - 3057meters

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

 

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

at this distance(1250-1290 m) is DM13, according to the Lanz-Odermatt equation, penetration ~110-120 mm RHA at @70°.

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It's interesting. Presentation (which contains this page) which available now on ontres.se is 110 pages long about 2-and-a-half years ago i've downloaded on my computer presentation which was 119

Waffentrager YOU FAKE BULLSXXT and FXXK OFF In case you guys here cannot read Japanese: It says "Height of lens assembly is about 380 mm" May be taken from a manual of digital came

I don't think there is a possible explanation, because people are beginning the argument from the wrong direction. People are making assumptions about the protection level, then try to find sources su

3 hours ago, Wiedzmin said:

it’s impossible to calculate rounds like DM13, BM42, BM15, M735 etc with L-O

Yet he has an equation for a steel-jacketed APDSFS. The question is how much they fit ...

Links(site Willi Odermatt) to report(PDF):

Minimum Impact Energy for KE-Penetrators in RHA-Targets European Forum on Ballistics and Projectiles, St. Louis (F), 2000

Perforation Equation for Jacketed Penetrators (with spread sheet)

Spoiler

CuftUed.png

at a distance of 1250 m, the impact velocity will be approximately 1556 m / s. LOS penetration 339 mm ro ~116 mm at 70o

1420 m/s(3057 m)  LOS penetration 299 mm ro ~102 mm at 70o

u3V2Kv9.png

But in any case, to say that these results are trustworthy, I can not)
There are too many unknown variables, such as the physicomechanical parameters of materials.

Although this once again proves that DM13 is a bad APDSFS

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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)

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On 2/27/2019 at 6:39 AM, CaptainBallistic said:

well dang thank you!

 

figure I should make it worth your while in return, ignore the stat cards.png's it's for a different purpose

Mostly just my estimations on two different American rounds with firing tables created and some minor sourcing. I had a friend with 3d software help get me the drag Coeff

 

also a pdf series that spans 3 years, a computational model for armor penetration:

 

Why worry about calculating firing tables for M829A1 when they're more or less publicly available?

 

 

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

The exterior doesn't look that similar though, CR1/M1 = lots of angles   leo 2 = more vertical, less angles. 

Unless the armour on the inside is angled, NERA like on CR1/M1 would be substantially less effective in a leo 2 turret as you know. 

 

"NERA like on [...] M1" is mounted at different angles than the external shape. It hardly proves or disproves that the same is possible with box-shaped armor modules.



 

YXyqVWh.jpg

M077aWP.jpg

 

 

 

T-90 also has a box-shaped turret, yet it has NERA, apparently mounted in the same fashion as done in the T-72B's turret:

 

t-72b_bulgingplates.jpg

 

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

 

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

Yes,  but that doesn't mean moving steel plates can't increase CE protection, there's ways to move those plates apart from having them sandwich a rubber liner.

 

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.

 

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

Seems I wasn't clear: what I meant with moving plates is armour similar to the B&V add-on or the Marder 1A3, they're all shock absorbing or are "encapsulated" in plastic/rubber with a thin layer.

 

These armor systems don't gain any significant amount of efficiency by "moving" the steel plates. The main functions of the shock absorbers are:

  • prevent the mounts for the spaced armor plates from breaking upon impact (which would happen with pure steel stand-offs of equivalent thickness)
  • allow easy replacement of damaged applique armor plates
  • 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)
On 4/11/2019 at 8:09 PM, Scav said:

Yes, this leads me to believe NERA as used on M1 or CR1 wouldn't be chosen, it focusses too much on CE.

 

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

 

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).

 

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

2AV didn't have the composite skirts of the XM-1, later on they adopted the heavy ballistic skirts though they don't look like those found on M1 as they cover less area but are thicker. 

Similarly, the turret bustle only features spaced armour sufficient to protect against autocannons, not thick composite as found on M1. 

 

Basically, everything indicates they were more concerned with frontal KE protection, in which case medium thickness, spaced steel armour layers make more sense than the design as featured on Mk5/2.

 

The difference in size of the heavy ballistic skirts is a result of the protection requirements, not of using a completely different type of armor. The US demanded protection of the crew compartment against a simulated RPG-7 along a 45° arc. This requirement didn't exist for the Leopard 2, thus the choice of skirt armor was different. The Leopard 2's heavy ballistic skirts are still NERA. 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 

 

"Medium thickness spaced steel armor layers" never makes sense, if you want protection against APFSDS and shaped charges. The protection requirement against shaped charges, while being lower than that of the Abrams, was still a lot higher than the required protection against APFSDS rounds.

 

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

Again, I don't see why multi layer spaced armour wouldn't work against APFSDS, it works for the Russians, why not upscale their other AFV armour designs?

 

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. 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.

 

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.

 

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

Only used two spaced layers though, with more you can use thinner layers and more space, both were prototypes too. 

Leopard 1A3 used 12-68mm, mostly around 30mm. 

If you have more space and weight to play with, dividing thicker plates into thinner ones (up to a point) is quite smart and more mass efficient, Russians came to the same conclusion and went from 60-105-50 to 50-35-50-35-50 or 60-15-15-15-15-15-15-15-50. 

Having plates around 1-2x the penetrator diameter in thickness seems to offer an increase in mass efficiency compared to thinner plates and thicker plates don't seem to offer much increase past that.

 

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. 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.

 

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°.

 

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

All of those instances they used the NERA sandwiches in high angles and shaped their armour appropriately, while internally angled plates are possible, it seems unlikely they'd be very angled on leo 2 according to some of those patents you've posted in the past. 

 

So, either the armour isn't mounted like in those patents and is quite angled on the inside (which would increase CE protection, probably beyond what leopard 2 had as requirement) or they used an other, less effective method to increase CE protection while keeping KE relatively high.

 

The patent images are from 1973 and illustrate mounting mechanisms, not armor arrays. Nothing prevents from the same concept being used for sloped multi-layer plates.

 

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

Shir 2, which pretty much was minimally changed, was adopted as CR1 and had substantially lower protection than some of those documents claimed. 

Atleast one document talks specifically about Shir 2 and gives it 325mm KE protection on the hull (what round we don't know), other documents comparing XM-1, leo 2, Shir 2 and MBT-80 say that Shir 2 doesn't reach protection requirement (which was still 430mm KE at this point) and is too slow. 

 

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

VuKQs9h.jpg

 

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

The document that gives CR1 500mm RHAe is a rather dubious one at best, the first page of which says Challenger I can only protect against a T-72 tank round at 1000m on the front of the turret..... (said round was given 480mm of penetration at 1km).

 

I would not call it dubious. There are multiple documents stating the same protection requirements/estimates; it seems like one of the most detailed/confirmed protection levels we have for "modern" MBTs (more detailed/cofnrumed than say the Leopard 2's initial frontal armor protection).

 

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

Newer documents that have surfaced specifically mention 105 and 120mm APDS being defeated and also some quoted russian round (probably the one from before), but the way it's worded indicates that only APFSDS rounds like the quoted russian round can be defeated.

 

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).

 

What was the definition of protection in the context of the document? Was it relevant in the context of the document that the tank could resist 105/120 mm APFSDS rounds or not? Is the phrasing indicating that Soviet APFSDS ammo can be resisted intentional? 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).

 

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...

 

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

The Brits have previously shown that they consider Russian APFSDS to be rather poor or inferior to their own. 

Meaning that protecting against 125mm WP APFSDS =/= protecting against 120mm NATO APFSDS.

 

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 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.

 

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.

 

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

Frankly, CR1's armour doesn't seem to have changed from Shir 2, which wouldn't have very impressive KE protection against LRPs (better than M1 is likely though). 

 

... and this conclusion is supported by no evidence.

 

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

That doc which claims 500mm KE also claims the hull was upgraded on "Challenger II" to 500mm, yet on Mk2 challenger the hull was the same thickness as before (~660mm LOS) and most definitely wouldn't reach such high numbers. 

 

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.

 

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

Somehow, between a FES (fully exposed stationary) "Challenger II" at 500m and 1000m, there's a 1.2% higher chance to kill at the longer range?

 

That could be a typo or an error in the computer simulation.

 

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

Even at 2000m there's a 50% chance to kill a "Challenger II" that has 500mm KE on hull and turret with a round that only penetrates 480mm at 1000m......

Let's not even mention that the Chieftain only has a 14% higher chance to be killed at the same range despite being rated at only 250mm.

 

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.

 

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

Even then.... 500mm KE against BM15/22? Yeah, okay I can see that. 

But 500mm KE against M829? Or even L23A1?

 

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?

 

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

Let's also ignore that a hull down stationary Challenger has the same 44% probability to be "killed" as a stationary Chieftain...... by an RPG-7.

 

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

 

That results in a similar kill probability? What a surprise...

On 4/14/2019 at 10:19 PM, Wiedzmin said:

ZXEorq3aMzI.jpg

 

100mm/70deg - 3057meters

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

 

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

 

Thanks for sharing, but unfortunately that alone doesn't say much. How exactly looked this spaced armor (steel hardness, spacing) and how good would the same APFSDS round perform against a solid 115 mm @ 70° target? From what date is this document?

 

Btw. the distances apparently should be 1,140 metres and 4,197 metres).

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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?

 

 

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On 3/31/2019 at 7:47 AM, Scav said:

 

 

 


In any case, reference threat for XM-1 (FSED I think) was XM579E1 (simulating 115mm APFSDS):

  Reveal hidden contents

image.png

Penetration was estimated at 161mm @60° and 1470m/s (either PB or 500m ish).
UK estimated XM-1 at 320-340mm, which coincides with the 115mm at 800-1200m requirement:

  Reveal hidden contents

2ate2CY.jpg

As previously pointed out in this thread.
This doesn't talk about the XM-1s before the FSED it seems (why would they talk about an outdated design?).

 

So either CIA was talking about IPM1 turret ("long turret") or they somehow increased KE values for turret while keeping CE the same OR CIA was overestimating own armour?....
 

Anyway,  BRL-1 or early versions of Chobham don't seem to be very good against KE relatively speaking, NERA part itself seems to do very little for KE, simulated ammo (XM579E1) isn't the best against composite materials or complex targets.

Perhaps OG M1 only had ~350mm effective against KE on both hull and turret and IPM1 increased this to 400 or slightly higher, but I don't think that increasing the thickness of the turret with more NERA seems very efficient against KE.
IPM1/M1A1 probably have below 470mm against KE on turret (XM579E1), but maybe more against old slug type APFSDS and definitely less against 80s long rods.

 

This probably led to DU equipped M1s...... to compensate for relatively poor KE protection.

 

 WYxn6dzl.jpg.ebb24f81e8134553a651b43fc4f

 

 

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. 

 

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

 

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?

 

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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...

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On 4/22/2019 at 4:48 PM, Scav said:

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?

 

 

Almost certainly this is the case.

On 4/22/2019 at 4:48 PM, Scav said:

 

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?)

 

 

There are no official sources that I can find. There are some who suggest that the IPM1 is BRL-1 but more of it, and the M1A1 is BRL-2.  There are many pictures of M1E1 with what appears to be different weight simulators. Perhaps this is evidence of this.

 

Not evidence of anything but interesting take.

 

https://www.quora.com/Does-an-M1-IP-have-the-same-armor-as-a-baseline-M1A1

 

"No, the Armor on the M1 IP is an advancement of the BRL-1 Burlington Armor on the M1. (mostly just more of it) It was optimized to protect against HEAT warheads.

The Early M1A1 had a reformulation called BRL-2 which put alot more emphasis on KE protection..."

From a poster named Glen Girona. A man who claims to be a former Abrams crew member and was a non technical member of the Foreign Technology Assessment Support team FTAS.

I don't have the complete paper unfortunately. I would assume that the time period referring to  the X-m1 and not M1 is the late 1970s or very early 1980s.  The options available would be M774 or XM833. A M833 fired at a MV of 1600ms (guess of 115mm MV) would pen 390-400mm of RHA at 0-10 degree from vertical  at 1200m this falls to around 360-370mm. It seems reasonable that estimates for the M1 putting the armor around 350-370mm across the frontal arc are accurate and use early monoblock apfsds ammunition as the standard.

 

On 4/22/2019 at 4:48 PM, Scav said:

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...

 

Not by that much. At APFSDS velocities Titanium alloys are 1.45-1.6 times as effective for a  given mass of RHA. For CE it has a TE of 0.9 at a density 0.6 the weight.

 

Tankograd also states the material between the titanium allows is comprised of Kevlar or something similar.

 

There are disadvantages to Ti mostly associated with cost and difficulty manufacturing and welding thick armor plates. Thinner plates fail due to adiabatic shearing unless a ductile backing is used (aluminum for example). 

 

Perhaps the M1 (BRL-1) use a mixture of HHS and Ti based NERA elements.

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2 hours ago, VertigoEx said:

 

Not by that much. At APFSDS velocities Titanium alloys are 1.45-1.6 times as effective for a  given mass of RHA. For CE it has a TE of 0.9 at a density 0.6 the weight.

 

Tankograd also states the material between the titanium allows is comprised of Kevlar or something similar.

 

There are disadvantages to Ti mostly associated with cost and difficulty manufacturing and welding thick armor plates. Thinner plates fail due to adiabatic shearing unless a ductile backing is used (aluminum for example). 

 

Perhaps the M1 (BRL-1) use a mixture of HHS and Ti based NERA elements.

 

On another thread, some people came to the conclusion that the titanium was not used as armor, but as mounting brackets for the NERA arrays. Due to the problems you mentioned, it would be illogical to use Ti as armor, but it would be completely sound to use it to support the armor. 

 

2 hours ago, VertigoEx said:

 

Almost certainly this is the case.

 

There are no official sources that I can find. There are some who suggest that the IPM1 is BRL-1 but more of it, and the M1A1 is BRL-2.  There are many pictures of M1E1 with what appears to be different weight simulators. Perhaps this is evidence of this.

 

Not evidence of anything but interesting take.

 

https://www.quora.com/Does-an-M1-IP-have-the-same-armor-as-a-baseline-M1A1

 

"No, the Armor on the M1 IP is an advancement of the BRL-1 Burlington Armor on the M1. (mostly just more of it) It was optimized to protect against HEAT warheads.

The Early M1A1 had a reformulation called BRL-2 which put alot more emphasis on KE protection..."

From a poster named Glen Girona. A man who claims to be a former Abrams crew member and was a non technical member of the Foreign Technology Assessment Support team FTAS.

I don't have the complete paper unfortunately. I would assume that the time period referring to  the X-m1 and not M1 is the late 1970s or very early 1980s.  The options available would be M774 or XM833. A M833 fired at a MV of 1600ms (guess of 115mm MV) would pen 390-400mm of RHA at 0-10 degree from vertical  at 1200m this falls to around 360-370mm. It seems reasonable that estimates for the M1 putting the armor around 350-370mm across the frontal arc are accurate and use early monoblock apfsds ammunition as the standard.

 

Lol, quora... 

 

Interesting though, I always assumed BRL-1 (Ballistic Research Laboratory; where the armor was made and tested) was the M1 array, and the M1 IP and M1A1 had the BRL-2, since their volume was similar, if not the same, but I could easily be wrong. 

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17 hours ago, Lord_James said:

 

On another thread, some people came to the conclusion that the titanium was not used as armor, but as mounting brackets for the NERA arrays. Due to the problems you mentioned, it would be illogical to use Ti as armor, but it would be completely sound to use it to support the armor. 

 

 

The source (1984 Army Magazine Volume 34 Pg 453) is rather clear in describing at least part of the armor.. " ..a pair of titanium alloy sheets sandwiching a layer of ballistic grade nylon.."

 

I don't have the source in front of me but I recall the common thickness of ballistic (hardened) grade titanium alloy plate around that time being approx 3/4 to 1 inch in thickness. 19-25mm.

 

Another possibility is the use of the titanium and ballistic fiber to encase and compress a ceramic backing layer. A low LD slug or APFSDS fragment impacting at yaw angle , a well confined ceramic layer with substantial backing would undergo interface defeat. 

 

17 hours ago, Lord_James said:

Lol, quora... 

 

Interesting though, I always assumed BRL-1 (Ballistic Research Laboratory; where the armor was made and tested) was the M1 array, and the M1 IP and M1A1 had the BRL-2, since their volume was similar, if not the same, but I could easily be wrong. 

 

I don't think that it is well documented, it is possible. The extra NERA elements and extra ~200 mm of space would increase its protection against contemporary soviet APFSDS (BM-26)  but do little against what was in the pipeline BM-42 etc. It seems logical to assume that during the development of the M829/829A1 that the USA felt that future soviet APFSDS would follow similar designs and performance. 

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1 hour ago, Zadlo said:

 

The same problems were also with thicker plates. Americans proved that in 1972 on 4" titanium plate.

 

hJj02OG.png

 

Yes the effect of a plug of material being separated and pushed out was an issue for stand alone Ti-alloys up until very recently. Very hard steel alloys often had that same issue for that matter. 

 

The alloys in a laminate configuration with multiple thin plates and backing of Kevlar, polycarbonate and dyneema seemed to transmit the stresses laterally much more effectively and solve the issue of shear failure rather well, having a greater TE then Ti alloys alone and a far better ME then RHA.  

 

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

Spoiler

20190427_142455.jpg

20190427_142452.jpg

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 :P

 

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.

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19 hours ago, Scav said:

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.

 

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

 

Nice work.

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On 4/17/2019 at 12:41 AM, SH_MM said:

How exactly looked this spaced armor (steel hardness, spacing

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)

 

On 4/17/2019 at 12:41 AM, SH_MM said:

 

Btw. the distances apparently should be 1,140 metres and 4,197 metres).

one mark - 200 meters so it's 1250-1290 and 4310, and my mistake about 3057 which is only showing difference, to much work lol...

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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:

Spoiler

3bm-15_high_obliquity.png

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.

 

 

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27 minutes ago, Scav said:

A thin steel plate put on brackets outside the tracks of the vehicle?

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...

 

29 minutes ago, Scav said:

That's quite a large space

it's not about posted image 

 

29 minutes ago, Scav said:

Also, junk US/UK test plates?

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 
 

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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.

Spoiler

unknown.png

Comparison of Canadian DU cores with UK WHA cores

 

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4 hours 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...

 

it's not about posted image 

 

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 
 

hardness is not the only parameter of steel. Moreover, at different angles there can be anisotropy of properties. Therefore, for an objective assessment, it is desirable to know as much information as possible.

Americans for tests often use MIL-A-12560, MIL-A-11356(cast ), MIL-A-46100, MIL-A-46186, MIL-A-24286, MIL-A-46173, MIL-A-46099. 

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Coming back to titanium, there's the another issue.

 

AFAIK in 2005 Americans started development of new production technology of titanium armor layers (whatever it may be) with using powder metallurgy and brand new alloy - Ti-5Al-2.5Fe. This alloy is cheaper and less toxic than Ti-6Al-4V but has a bit worse effectiveness. Using that alloy in M1 may cause that armor should be thickened (by around 5 - 10% I think) to achieve similar protection to armor using Ti-6Al-4V.

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9 hours ago, Zadlo said:

Coming back to titanium, there's the another issue.

 

AFAIK in 2005 Americans started development of new production technology of titanium armor layers (whatever it may be) with using powder metallurgy and brand new alloy - Ti-5Al-2.5Fe. This alloy is cheaper and less toxic than Ti-6Al-4V but has a bit worse effectiveness. Using that alloy in M1 may cause that armor should be thickened (by around 5 - 10% I think) to achieve similar protection to armor using Ti-6Al-4V.

 

The USA has been working with powder metallurgy for some time. No surprise they moved onto Titanium alloys. There is good evidence that the M829A2 is improved in such ways.  I did some research about a year ago before my hard drive crash but wrote on SB form..that in the late 1980s the USA was conducting very serious research into improving " tensile and yield strength of heavy metal alloys. In some cases gaining improvements of 300-400% through some methods that caused  dissolution uniform recrystallization of ultra fine powders of various metals mixed with the main heavy metal. "

 

I will look for the paper to provide evidence of this.

 

Perhaps this is the improvement or one of a few of HAP-1---->HAP-2 also.

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On 4/20/2019 at 3:05 PM, Scav said:

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. 

 

This is all just speculation on your part. The available sources are not enough to make any such conclusions. We know that the Leopard 2AV was designed to resist a 105 mm APFSDS round fired from the smoothbore gun fielded on the earlier prototypes (from an unknown distance) and the MILAN warhead, but that's all. Aside of the fact that MILAN penetrates 530 mm instead of 580 mm based on the British evaluation of the missile, the problem remains that we do not know if the missile was used with built-in stand-off distance or placed as a distance - something that has been done in multiple other tests. The British concluded that increasing the stand-off distance could yield a similar performance gain as increasing the warhead diameter, reaching a penetration value of more than 600 mm against steel armor is possible when placing the shaped charge warhead at (near) optimum stand-off distance, i.e. coming very close to the US reference warhead.

 

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. 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! 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.

 

On 4/20/2019 at 3:05 PM, Scav said:

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.

 

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.

 

The Leopard 2 was estimated to stop a non-existant 125 mm APFSDS by a publicly available Swiss magazine one year before the Leopard 2 was even tested in Switzerland. The same magazine used incorrect armor values for the T-72 included incorrect descriptions of the Soviet APFSDS rounds and also using the same protection values for M1 Abrams (!) and Leopard 2 - specifically the latter is very questionable, given that the British believed that 125 mm APFSDS round could defeat the Abrams at up to 4 kilometers distance.

 

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?

 

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.

 

On 4/20/2019 at 3:05 PM, Scav said:

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.....

 

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".

 

On 4/20/2019 at 3:05 PM, Scav said:

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)

 

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.

 

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.

 

On 4/20/2019 at 3:05 PM, Scav said:

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

 

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.

 

On 4/20/2019 at 3:05 PM, Scav said:

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

 

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". 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).

 

On 4/20/2019 at 3:05 PM, Scav said:

Thinner and lighter? Where did you see that?

 

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.

 

On 4/20/2019 at 3:05 PM, Scav said:

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

 

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.

 

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.

 

On 4/20/2019 at 3:05 PM, Scav said:

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? 

 

Because you are mixing different sources. The Chieftain with Stillbrew armor was not believed to stop the future Soviet APFSDS  rounds with more than 500 mm penetration, but what the UK believed to be the current main round with tungsten-carbide core used by the T-72. You can even read in your own quote that the penetration of 530 mm steel at point-blanc was estimated for the "successor Soviet 125 mm round" with tungsten monobloc penetrator. The Stillbrew armor was not meant to defeat such rounds, but performed good against the L23 APFSDS, which was believed to be superior to the Soviet APFSDS rounds with tungsten carbide slugs inside the steel penetrators.

 

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) - 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.

 

On 4/20/2019 at 3:05 PM, Scav said:

Optimised against APDS

 

Source?

 

On 4/20/2019 at 3:05 PM, Scav said:

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?

 

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. 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).

 

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

 

On 4/22/2019 at 12:23 AM, VertigoEx said:

WYxn6dzl.jpg.ebb24f81e8134553a651b43fc4f

 

 

I found this and reposted this on the SB forum.

 

Interested in what others here think..

 

This is from the same document describing several heavy IFV alternatives to the Bradley and containing the armor protection requirements for the M1 Abrams. Apparently no prototype was ever built.

 

On 4/27/2019 at 4:17 PM, VertigoEx said:

The source (1984 Army Magazine Volume 34 Pg 453) is rather clear in describing at least part of the armor.. " ..a pair of titanium alloy sheets sandwiching a layer of ballistic grade nylon.." 

 

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

 

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

 

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