Contemporary Western Tank Rumble!

[CaptainBallistic]

Greetings from the Gaijin's Snailhouse forums I have come to ask questions and share information as needed.

 

I had a quote provided to me that apparently was sourced from somebody here.

Spoiler

"The M1A1 HA added 4,400 lbs of weight according to the weight "Historic Weight Growth of U.S. Army Combat Vehicle Systems" by the Military Traffic Management Command, this is just ~1,995 kg. Apparently, the adoption of the heavier T158 tracks raised the weight of the M1A1 from 120,000 lbs to 130,800 lbs, thus creating the illusion of a much larger weight gain for the M1A1HA (which always uses the T158 tracks) due to incorrect comparisons with the M1A1 with T156 tracks. The M1A1 with T158 tracks (59.1 metric tons) is only ~ 2 tons lighter than the M1A1HA with first generation DU armor (61.2 metric tons). Two metric tons are equal to about ~254 mm RHA per square metre. Given that M1A1's turret cheeks cover an area of ~1.73 m², this means the armor weight increase is roughly equal to 147 mm RHA."

1

 

One thing I'd like to ask is where somebody can find "Historic Weight Growth of U.S. Army Combat Vehicle Systems" by the Military Traffic Management Command" So I can verify the information provided myself and seek out more accurately the effects of a DU mesh against KE penetrators. Currently, the great and almighty search engines provide nothing for me as of yet.

 

I'm mostly just trying to get all the information I possibly could about the Abrams protection, firepower, FCS, APS, and Mobility and protection seems to be one of the few things I need to be covered in detail beyond just speculated guesses and Swedish trial graphs that tbh are somewhat hard to read accurately.

[Belesarius]

52 minutes ago, CaptainBallistic said:

Greetings from the Gaijin's Snailhouse forums I have come to ask questions and share information as needed.

 

I had a quote provided to me that apparently was sourced from somebody here.

  Hide contents

"The M1A1 HA added 4,400 lbs of weight according to the weight "Historic Weight Growth of U.S. Army Combat Vehicle Systems" by the Military Traffic Management Command, this is just ~1,995 kg. Apparently, the adoption of the heavier T158 tracks raised the weight of the M1A1 from 120,000 lbs to 130,800 lbs, thus creating the illusion of a much larger weight gain for the M1A1HA (which always uses the T158 tracks) due to incorrect comparisons with the M1A1 with T156 tracks. The M1A1 with T158 tracks (59.1 metric tons) is only ~ 2 tons lighter than the M1A1HA with first generation DU armor (61.2 metric tons). Two metric tons are equal to about ~254 mm RHA per square metre. Given that M1A1's turret cheeks cover an area of ~1.73 m², this means the armor weight increase is roughly equal to 147 mm RHA."

1

 

One thing I'd like to ask is where somebody can find "Historic Weight Growth of U.S. Army Combat Vehicle Systems" by the Military Traffic Management Command" So I can verify the information provided myself and seek out more accurately the effects of a DU mesh against KE penetrators. Currently, the great and almighty search engines provide nothing for me as of yet.

 

I'm mostly just trying to get all the information I possibly could about the Abrams protection, firepower, FCS, APS, and Mobility and protection seems to be one of the few things I need to be covered in detail beyond just speculated guesses and Swedish trial graphs that tbh are somewhat hard to read accurately.

Welcome to SH.

If you haven't yet, please read this thread.

Good luck in your search for information. You may want to check out this thread as well for information on the Abrams.

 

[SH_MM]

4 hours ago, CaptainBallistic said:

One thing I'd like to ask is where somebody can find "Historic Weight Growth of U.S. Army Combat Vehicle Systems" by the Military Traffic Management Command"

 

https://www.sddc.army.mil/sites/TEA/Functions/Deployability/TransportabilityEngineering/Transportability Engineering Publications/WeightGrowthPaper082702.pdf

[CaptainBallistic]

19 hours ago, SH_MM said:

 

https://www.sddc.army.mil/sites/TEA/Functions/Deployability/TransportabilityEngineering/Transportability Engineering Publications/WeightGrowthPaper082702.pdf

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

Spoiler

https://drive.google.com/open?id=1ISy-tzCAEvgV-vPZWiMKD8jiOpbmXVuN

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:

Spoiler

https://drive.google.com/open?id=1Ra27D788occMJ6RMd2aoJU_3l-vl-QhN

 

[lubobaricak]

https://cloud.mail.ru/public/FVLe/iUZw87trH it was removed can someone send me working link?

[skylancer-3441]

/it took me some time, which i spent unsuccessfully trying to google that link without using quotation marks, which was stupid, before i recalled that there is a search bar on this forum, up there on the right, which lead me to my own post.../
This one:

On 3/8/2018 at 3:05 PM, skylancer-3441 said:

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 pages long. Apparently it's exactly the same as one available now online, except for some pages on tank protection https://cloud.mail.ru/public/FVLe/iUZw87trH 
(according to Chrome history file, which i've backed up in dec.2015 and still have now, this pdf was without a doubt downloaded from ontres.se https://i.imgur.com/ysAJQgr.png)

it's dead because ... well, I don't remember exactly, I either moved or renamed folder which contained that file, so cloud.mail.ru broke that link. And unfortunatelly they use autogenerator for public links, so i can't "revive" it, only create a new one https://cloud.mail.ru/public/72VE/BGtaQEVtN
btw, back then this file was immediatelly reuploaded by someone else to other place https://drive.google.com/open?id=1gwjvEs4MGotOtyQKup3BVIoFUA4NUwXo

[Scav]

Armour dimensions of the M1A1 in the American Heritage museum (made by a friend):

Spoiler

Hull: 24" or 609.6mm to weldline, rumoured 4" plate behind that (101.6mm)

(Quoting friend)

Spoiler

 

From drivers hatch to feet is 26" 

From hatch to outer plate is 59",

Perpendicular thickness is 33"

 

Seems like there's some empty space there, or he could've missed something, but he agreed that LOS thickness was ~732mm.

 

Turret cheek loader: 29" or 736.6mm perpendicular

From front face to loader's hatch on outside: 78" (he had to hook the tape over, so -3" on the pic you see)  and from loader's hatch on inside to armour = 41", so turret cheek armour from front = 37" or 939.8mm.

 

Turret cheek gunner: 29" or 736.6mm perpendicular, less angled than loader's side, no measurement to commander's hatch and inside to get overal thickness but we assumed  same inner plate thickness.
(maybe the GPS wouldn't be able to fit if it was bigger?)
 

So, hull of M1 (1980) was same thickness and turret most likely the same too (732mm LOS), so how come they gave turret higher protection values than hull?

Seems a bit odd, CIA gave turret 400mm KE (on a turret variant, we don't know which) and 750mm CE, but hull generally gets values of 350mm KE and 750mm CE.....

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

Spoiler

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:

Spoiler

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.

[Zach9889]

Quote

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:

 

Perhaps the 161mm @60°/320mm-340mm figures are for protection along the frontal arc of the turret (+30°). This would put the those figures roughly in line (~393mm) with the 400mm cited by the CIA if they were only considering 0° impact obliquity.

 

Quote

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

This is kind of obvious. I believe there was a underestimation of Soviet KE projectiles by NATO going into the 80's that snared both M1 and Leo 2 protection development. You can see both designs upgrade their inadequate armor through the 80's to compensate for those deficiencies. 

[Wiedzmin]

On 3/31/2019 at 3:47 PM, Scav said:

poor KE protection.

all early AFPSDS work not so good against spaced(steel spaced plates) armour, for example you can stop L23A1 point blank on centurion hull front, adding 4 not very thick plates on top of it, with spacing between each plate

 

all this "360mm vs KE" "over 800mm vs KE" etc useless, unless you know what round exactly was used, and at whick striking velocity armour can withstand that round.

[Scav]

7 hours ago, Wiedzmin said:

all early AFPSDS work not so good against spaced(steel spaced plates) armour, for example you can stop L23A1 point blank on centurion hull front, adding 4 not very thick plates on top of it, with spacing between each plate

 

all this "360mm vs KE" "over 800mm vs KE" etc useless, unless you know what round exactly was used, and at whick striking velocity armour can withstand that round.

Ofcourse, which is why it's very interesting that the reference threat was the 152mm XM579E1, which is essentially the predecessor to the XM735 APFSDS.

That one is teardrop shaped (as we all probably know):

Spoiler

It also has a 97.5% tungsten alloy which gives it 18.5g/cc density (page 3).
This type of penetrator probably isn't very good against complex armour types, the tip and tapering width wouldn't be advantageous.
So, M774 or DM23 (120) for instance will probably perform better than it against the composite of the M1.
 

Also, what's the cent vs L23A1 story?
Haven't heard of that one yet.
 

11 hours ago, Zach9889 said:

Perhaps the 161mm @60°/320mm-340mm figures are for protection along the frontal arc of the turret (+30°). This would put the those figures roughly in line (~393mm) with the 400mm cited by the CIA if they were only considering 0° impact obliquity.

Not sure how that would work, the hull front is ~732mm from straight front and so is the turret, meaning that the turret at + 30° would have less LOS.
So while the hull has it's worst protection from straight front, that lines up with the best protection on the turret front (atleast in terms of LOS, we don't know composition apart from exterior plate thickness ofcousre).
Essentially, I doubt that the hull's 845mm (~732mm at 30°) would be as good as the turret's 732mm (at 0°), it just doesn't make sense.
 

11 hours ago, Zach9889 said:

This is kind of obvious. I believe there was a underestimation of Soviet KE projectiles by NATO going into the 80's that snared both M1 and Leo 2 protection development. You can see both designs upgrade their inadequate armor through the 80's to compensate for those deficiencies. 

Depends, did they really underestimate the USSR ammo when we take the design of said ammo into consideration?

They underestimated the raw penetration of USSR ammo, but is the performance that good against composites?
I tend to think not.
The slug type APFSDS lose almost 50% of their penetration at 30° angles because the slug and steel rod seperate (starts happening at 15°), the slug itself would be great against RHA because it's made of WC and going very fast while being very small (70x20mm), but it weighs next to nothing (270g) and due to material type would be very prone to shattering on spaced armour plates.

According to the Bauman book, BM15 is 32.1% less effective against 50mm RHA + 70mm air (same as core length) + 200mm RHA than against a 250mm plate, all at 0°.

 

Incidently, these are common characteristics on NATO MBTs such as the M1 and leopard 2, angles on the turret as well as the hull exceed the 30° value in a lot of cases, while such small airgaps are probably quite common as well.

All of this combined seems to indicate that against BM15 or even BM22, both the M1 and leopard 2 would have decent to good protection on the turret, it's only when you look at BM26/29 that both tanks start to become more vulnerable.

Even then, while M1 doesn't seem very impressive, leopard 2's turret should be notably better, IMO Krapke's threat diagram could apply to BM26/29:

Spoiler

All of this is speculation, but it does seem plausible.

 

BM32/42 are a different story though and for this the 1988 upgrades would definitely be necessary, though they do seem sufficient to block said ammo even at PB.

We should also note that during most of the 80s, BM22/26 were the most common rounds and BM32/42 wouldn't have been very common.

 

IMO, US got the CE protection just right and Germany got the KE protection relatively right, both could've been better, but then they might've ended up doing an MBT-80.

[SH_MM]

On 3/31/2019 at 2:47 PM, Scav said:

Hull: 24" or 609.6mm to weldline, rumoured 4" plate behind that (101.6mm)

 

Based on the drawings of the special armor array of the original M1 Abrams, the weldline (shown as triangle) is located on the center of the back plate. Maybe that has changed in later production batches, but it implies an armor thickness of ~650-660 mm.

 

 

 

On 3/31/2019 at 2:47 PM, Scav said:

So, hull of M1 (1980) was same thickness and turret most likely the same too (732mm LOS), so how come they gave turret higher protection values than hull? 

 

I don't know how accurate the figures are, but the developers of the online video game War Thunder measured the thickness of an original M1 Abrams tank located in a military museum in Minnesota; based on their figures, the early M1 Abrams had thinner armor:

The outer steel plate of the turret armor has a thickness of 38.1 mm, while the special armor cavity on the right turret front (in front of the gunner's sight) supposedly is either 19.5 inches or 490 mm thick (slightly different values cited on the English and the Russian articles. Unless the M1 Abrams turret has an unreasonable thick back plate, it should be assumed that the M1 Abrams from 1980 has an armor thickness of 620-650 mm (with slope this might end up as 732 mm LOS).

 

I.e. the turret front has the same thickness as minimum along the 50° arc that the hull has at 0°.

 

On 3/31/2019 at 2:47 PM, Scav said:

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?....

 

The CIA later accessed the M1A1 with 380 mm steel-equivalent protection. These figures are likely related to different criteria (impact angle, reference projectile, etc.).

 

On 4/2/2019 at 8:36 AM, Wiedzmin said:

all this "360mm vs KE" "over 800mm vs KE" etc useless, unless you know what round exactly was used, and at whick striking velocity armour can withstand that round.

 

In general yes, but we know what projectile the United States military used for testing the armor of the M1 Abrams and what it was meant to represent.

 

On 4/2/2019 at 4:55 PM, Scav said:

All of this combined seems to indicate that against BM15 or even BM22, both the M1 and leopard 2 would have decent to good protection on the turret, it's only when you look at BM26/29 that both tanks start to become more vulnerable. 

Even then, while M1 doesn't seem very impressive, leopard 2's turret should be notably better, IMO Krapke's threat diagram could apply to BM26/29:

 

The figure from Paul-Werner Krapke's book apparently uses figures from a Swiss magazine, which was published in 1980. The Swiss article speaks about a Soviet 125 mm APFSDS round made of tungsten with length-to-diameter ratio of 12, 48 mm diameter  and 575 mm length - that would be better than 3BM-42 and 3BM-32, even considering its sligthly lower muzzle velocity of 1,650 m/s. The rest of the article also contains some further errors...

 

There is apparently some truth in the engagement ranges regardless of the Swiss articles, as we can see by looking at the data from the Swedish leaks and other sources. The Leopard 2 likely had better armor protection against KE than the M1 Abrams, given all factors considered (armor thickness, armor weight, confirmed use of higher quality steel alloys with greater hardness, testing the armor against a more powerful round, etc.).

[Wiedzmin]

17 hours ago, SH_MM said:

The Leopard 2 likely had better armor protection against KE than the M1 Abrams,

it can have, but basic requirements for 2AV after 1977 and first 2A0, is 105mm 38mm APFSDS (https://fromtheswedisharchives.wordpress.com/2019/01/03/rheinmetall-105-cm-smoothbore-performance/ this one), and 120mm DM13 from 1km IIIRC(which is rather poor perfomance round) + protection against Milan ATGM 

 

all early tanks have "good" protection not because it's have "super-duper-chobham-ceramic-magic-unicorn-armour" but because of shitty APFSDS and APDS used in trials against it at the moment(soviets did it(probably the worst in quality APFSDS and APDS ), americans did it, germans, brits etc), and only after receiving some "emergency calls" like M111 for T-72 etc, "very skilled smart engineers" starts making some improvements over theirs "great inventions" 

 

and if tank "A" give protection against round "B" in country "C", it doesnt guarantee you that it will protect from round "D" in country "E", and so on... 

[SH_MM]

3 hours ago, Wiedzmin said:

is 105mm 38mm APFSDS (https://fromtheswedisharchives.wordpress.com/2019/01/03/rheinmetall-105-cm-smoothbore-performance/ this one), and 120mm DM13 from 1km IIIRC(which is rather poor perfomance round)

 

It is better and more modern than the XM578E4 APFSDS used in the United States. That is why I mentioned " testing the armor against a more powerful round" as one of the reasons, why the series production Leopard 2 seems to be better protected against KE.

 

3 hours ago, Wiedzmin said:

and if tank "A" give protection against round "B" in country "C", it doesnt guarantee you that it will protect from round "D" in country "E", and so on... 

 

Agreed. But unless armor technology is very different between the M1 Abrams and the Leopard 2, the latter tank (having thicker and more densely-packed armor arrays) should have an advantage. If more sources become available, the situation has to be accessed again to see if this thesis is correct.

[Wiedzmin]

1 hour ago, SH_MM said:

It is better and more modern than the XM578E4 APFSDS used in the United States

US also used DU XM774 28mm diam(serial M774 has 26), so it's really unknow how well M1 withstood this level of threat 

 

[SH_MM]

According to the IFV document from which the table was taken, the XM774 was tested against a re-modelled armor array after the M1 Abrams had already finished testing.

[Scav]

22 hours ago, SH_MM said:

Based on the drawings of the special armor array of the original M1 Abrams, the weldline (shown as triangle) is located on the center of the back plate. Maybe that has changed in later production batches, but it implies an armor thickness of ~650-660 mm.

I can ask my friend again to get a better measurement from the inside using the driver's hatch as reference, though I don't think drawings are necessarily 100% accurate.

 

22 hours ago, SH_MM said:

I don't know how accurate the figures are, but the developers of the online video game War Thunder measured the thickness of an original M1 Abrams tank located in a military museum in Minnesota; based on their figures, the early M1 Abrams had thinner armor:The outer steel plate of the turret armor has a thickness of 38.1 mm, while the special armor cavity on the right turret front (in front of the gunner's sight) supposedly is either 19.5 inches or 490 mm thick (slightly different values cited on the English and the Russian articles.

Quoting their article:

Quote

The very lower plate which connects the lower glacial to the hull was indeed 22 inches from front to back demonstrating the positioning rear cavity for the front armor. However, on the sides at the weld seam with the hull is located the mounting bulges for the rear conventional 101mm RHA plate which was visually distinguishable in the design was also clearly available to us allowing us to appropriately verify that we indeed had the lower front assembly on the in-game model correctly positioned as according to the  design document and the physical layout on the tank.

Seems like they did verify where the 101mm plate was mounted/welded, I think the only question that remains is how it was mounted, either forward of the weld, in the middle of the weld or behind the weld....

I agree that perhaps more investigation is required.

 

As for the turret, is there any indication that the IPM1/M1A1 increased the front plate thickness?
I know of the appliqué plates mounted on M1A1s in GW1, but apart from that, I've never seen much on it.

 

22 hours ago, SH_MM said:

Unless the M1 Abrams turret has an unreasonable thick back plate, it should be assumed that the M1 Abrams from 1980 has an armor thickness of 620-650 mm (with slope this might end up as 732 mm LOS).

 

I.e. the turret front has the same thickness as minimum along the 50° arc that the hull has at 0°.

That was my conclusion as well.

 

22 hours ago, SH_MM said:

The CIA later accessed the M1A1 with 380 mm steel-equivalent protection. These figures are likely related to different criteria (impact angle, reference projectile, etc.).

To be fair, I don't entirely trust the CIA in either case.

But this does match up better with all the other circumstancial indicators.

 

22 hours ago, SH_MM said:

The figure from Paul-Werner Krapke's book apparently uses figures from a Swiss magazine, which was published in 1980. The Swiss article speaks about a Soviet 125 mm APFSDS round made of tungsten with length-to-diameter ratio of 12, 48 mm diameter  and 575 mm length - that would be better than 3BM-42 and 3BM-32, even considering its sligthly lower muzzle velocity of 1,650 m/s. The rest of the article also contains some further errors...

L/D of 12?
Huh.... could it be that they simply used DM13 APFSDS as simulant and upscaled it a bit?

I don't think we should assume BM42 or 32 for that matter, both wouldn't be known to the west at this time, let alone be used for estimates.

 

22 hours ago, SH_MM said:

There is apparently some truth in the engagement ranges regardless of the Swiss articles, as we can see by looking at the data from the Swedish leaks and other sources. The Leopard 2 likely had better armor protection against KE than the M1 Abrams, given all factors considered (armor thickness, armor weight, confirmed use of higher quality steel alloys with greater hardness, testing the armor against a more powerful round, etc.).

Yeah, couple that with the lower requirement for CE protection, it does add up.

 

5 hours ago, Wiedzmin said:

it can have, but basic requirements for 2AV after 1977 and first 2A0, is 105mm 38mm APFSDS (https://fromtheswedisharchives.wordpress.com/2019/01/03/rheinmetall-105-cm-smoothbore-performance/ this one), and 120mm DM13 from 1km IIIRC(which is rather poor perfomance round) + protection against Milan ATGM 

DM13 is still superior to M735, especially if fired from the 120.

Seems like it was designed to work against composites or spaced armour, unlike M735.

 

5 hours ago, Wiedzmin said:

all early tanks have "good" protection not because it's have "super-duper-chobham-ceramic-magic-unicorn-armour" but because of shitty APFSDS and APDS used in trials against it at the moment(soviets did it(probably the worst in quality APFSDS and APDS ), americans did it, germans, brits etc), and only after receiving some "emergency calls" like M111 for T-72 etc, "very skilled smart engineers" starts making some improvements over theirs "great inventions" 

True, though it does appear as if leo 2 had better KE performance, while being tested against slightly less shit rounds than the M1.

Besides, I'd still consider DM13 superior to BM15/22, specifically against composites.

I very much have come to a similar conclusion though, M1 seems overrated in terms of armour protection due to the requirements often being neglected, same thing with the Challenger 1.

The only one of the modern MBTs that seems to have been tested and designed with a somewhat modern threat is leopard 2.

Though it clearly "lacks" in CE protection as a result.

 

5 hours ago, Wiedzmin said:

and if tank "A" give protection against round "B" in country "C", it doesnt guarantee you that it will protect from round "D" in country "E", and so on... 

Sure, but we don't have the luxury of testing it all, so we have to do with estimates and educated guesses :).

 

1 hour ago, SH_MM said:

Agreed. But unless armor technology is very different between the M1 Abrams and the Leopard 2, the latter tank (having thicker and more densely-packed armor arrays) should have an advantage. If more sources become available, the situation has to be accessed again to see if this thesis is correct.

I think the requirement, previous development and specific steels used already indicate that the armour technology isn't the same.

Requirement leopard 2AV: Milan 1 (580mm RHA) and 105mm DM13 APFSDS

Requirement M1: 127mm SC (I-TOW?)(640mm RHA) and XM579E1 (pre-proto M735)

Already we can see the preference lies more with CE than KE for the M1 and the opposite for leo 2.

 

Previous development: leopard 2 PTs, spaced steel with HHA and ballistic shaping (minimising profile), leopard 1A1A1 B&V add-on (perforated steel plates with plastic/rubber cover).....

Regarding the steels used, you yourself have pointed this out in the past (thanks for that):

Spoiler

It doesn't list plates thicker than 45mm, indicating that leopard 2 doesn't use thick backplates such as on M1 or CR1.

These would be necessary (I should say preferred) for Chobham style composite.

 

So, if the KE protection doesn't come from the front and backplate, it must come from the inserts.

 

M1/CR1: 30-50mm frontplate (RHA) -> NERA sandwiches with thin steel plates (RHA) and thicker rubber/plastic liners -> thick backlayer 100-110mm (CHA/RHA).

Leopard 2: 30-45mm frontplate (HHA) -> spaced steel plates (HHA) between 10-45mm -> 40-45mm backplate (RHA/HHA?).

 

Looks quite different to me, combine that with how the Germans used suspended/dampened spaced armour before (B&V upgrade) it seems quite likely they continued down this path and maybe only used some parts of the UK-GER info sharing from 1974.

Let's not forget that the same exact thing seems to be the case with the leopard 2A5 add-on.... spaced steel with a rather low rubber-steel ratio.

 

Just now, SH_MM said:

According to the IFV document from which the table was taken, the XM774 was tested against a re-modelled armor array after the M1 Abrams had already finished testing.

Oh, dangit, I forgot to look the document itself up....

BRB.

[Wiedzmin]

16 minutes ago, Scav said:

Besides, I'd still consider DM13 superior to BM15/22, specifically against composites.

DM13 same shitty round, have some report about it i think. need a lot of time to find it...

[AC GiantDad]

On 4/7/2019 at 9:13 AM, Wiedzmin said:

DM13 same shitty round, have some report about it i think. need a lot of time to find it...

not really, DM13 uses a better penetrator slug made of WHA instead of WC and DM13 has a significantly better construction than BM-15/22, rather than simply having a slug that sits inside the nose of the penetrator body, the slug extends through the length of the penetrator body, meaning that it's less vulnerable to the shear stresses found at high obliquities. It's the same reason M735 and XM578E1 perform better at these high obliquities as well

[Wiedzmin]

14 hours ago, AC GiantDad said:

is a significantly better construction

doesn't mean that is significantly better in penetration

 

14 hours ago, AC GiantDad said:

less vulnerable to the shear stresses found at high obliquities

i will find report , there was test agains 70degree 100mm RHA + 15 or 30mm HHA IIRC, which round coudn't penetrate 

[SH_MM]

On 4/7/2019 at 3:53 PM, Scav said:

L/D of 12?
Huh.... could it be that they simply used DM13 APFSDS as simulant and upscaled it a bit? 

 

These are the statements from a publicly available Swiss magazine in 1980, I doubt that they had any access to actuall test results or intelligence reports regarding actual Soviet ammunition or the armor of the Leopard 2. The article is a bit generic and uses generalizations regarding Soviet technology and armor protection.

 

On 4/7/2019 at 3:53 PM, Scav said:

DM13 is still superior to M735, especially if fired from the 120. 

Seems like it was designed to work against composites or spaced armour, unlike M735. 

 

It was designed to defeat spaced armor according to German patents, but it wasn't really that much better. At least an "improved" M735 lead to Germany to cancel all development efforts of the 105 mm smoothbore gun and fit some of the prototypes with the L7A3 rifled gun, because the M735 manage to achieve "similar" performance.

 

On 4/7/2019 at 3:53 PM, Scav said:

It doesn't list plates thicker than 45mm, indicating that leopard 2 doesn't use thick backplates such as on M1 or CR1. 

These would be necessary (I should say preferred) for Chobham style composite.

 

You are assuming that the backplate has to be part of the structural steel. That doesn't have to be the case. Already when working on the Chieftain Mark 5/2 concepts (aluminium construction with Chobham armor), the British included thick steel back plates as part of the armor modules, as the aluminium itself wasn't suited for the job. The Leopard 2 could follow a similar approach, simply use a replaceable backplate (of the armor array) for easier damage repair and future upgrades. Patents from the late 1970s suggest that Germany and France prefered multi-layered backplates made out of different steel alloys and/or including non-metallic elements (e.g. glass, ceramics).

 

On 4/7/2019 at 3:53 PM, Scav said:

Leopard 2: 30-45mm frontplate (HHA) -> spaced steel plates (HHA) between 10-45mm -> 40-45mm backplate (RHA/HHA?). 

 

That doesn't make any sense. The document seems to list the steel plates delivered to the company responsible for welding the turret shell, not the company manufacturing the armor package. The armor technology as described by you was used in 1970-1974, the T14 mod. introduced actual composite armor including non-metallic and elastic materials (according to Krapke). Patents from the late 1970s and early 1980s suggest that Germany used NERA with a multi-layered backplate.

 

On 4/7/2019 at 3:53 PM, Scav said:

Let's not forget that the same exact thing seems to be the case with the leopard 2A5 add-on.... spaced steel with a rather low rubber-steel ratio.

 

It's not rubber though, that's why it can be so thin.

 

On 4/8/2019 at 12:25 PM, Wiedzmin said:

i will find report , there was test agains 70degree 100mm RHA + 15 or 30mm HHA IIRC, which round coudn't penetrate 

 

Well, 130 mm at 70° is already 380 mm along the line of sight. Add to this that the high-hardness steel has a higher thickness efficiency and spaced armor improves protection, then you have a target that provides more than 400-450 mm steel-equivalent protection against older rounds. It is not unexpected for the DM13 to fail at penetrating that armor array, given that it likely cannot defeat even 400 mm of steel armor.

 

The 38 mm KE round fired from the 105 mm smoothbore gun managed to defeat several spaced targets in Sweden (although a lot worse than 100 mm RHA + 30 mm HHS), i.e.:

- 10 mm steel HB 379 + 25 mm iron + 60 mm steel HB 255-293, all sloped at 65° (225 mm at line of sight) at long ranges (even defeated with a velocity of only 1,150 m/s at 250 m)

- 10 mm steel HB 379 + 25 mm iron + 80 mm steel HB 269, all sloped at 65° (272 mm at line of sight), the 38 mm KE round created a bulge when hitting with a velocity of 1,407 m/s at 250 m

- 40 mm steel HB 270 + 90 mm steel HB 269, all sloped at 60° defeated with a velocity of 1,268 m/s at 250 m

[Scav]

27 minutes ago, SH_MM said:

You are assuming that the backplate has to be part of the structural steel. That doesn't have to be the case. Already when working on the Chieftain Mark 5/2 concepts (aluminium construction with Chobham armor), the British included thick steel back plates as part of the armor modules, as the aluminium itself wasn't suited for the job.

The reason for having thick backplates in the first place is due to this initially being an upgrade program, they would add composite packages to existing Chieftain tanks to improve their armour, they then found that having these thicker back layers is advantageous to minimising damage behind armour.

In the case of the aluminium versions, this was probably because aluminium simply isn't good enough on it's own or would be too bulky otherwise.

Keep in mind that these proposals and armour designs weren't very good against KE for how bulky they were, Mk5/2 was only rated for 120mm APDS from 1300m for instance (on glacis+turret front, noseplate was overmatched).

Everything more or less indicates that the actual NERA sandwiches themselves did very little against KE, most of the protection coming from the faceplate (around 50mm) and the backplate (80-110mm), both of which combined are already sufficient to stop 120mm APDS at ranges exceeding 1km.

Spoiler

https://cdn.discordapp.com/attachments/508046972075245568/565250735122415636/20131231_112301.jpg

https://cdn.discordapp.com/attachments/508046972075245568/565250791896776756/20131231_112248.jpg

 

And while the UK did share info with Germany, it seems rather unlikely that they would adopt the same kind of armour style as they simply had different requirements and ideas.

Germany already had experience with spaced armour and it's higher KE efficiency, they were also looking into HHA (jkeiler prototypes, 1A3/4), it's quite likely they kept further developing into more complex arrays with more plates of similar thicknesses as before.

Whereas the UK was coming at this from a different angle, previously they'd used thick cast armour with ballistic shapes, adding to this something to counter HEAT warheads (NERA) and something else to make it more durable.... so you get a completely different armour design.

 

IMO it's very weird if Germany would've done a 180 and adopted the UK style of composite/NERA, it seems far more likely that they simply kept working on more complex spaced armour combined with suspended or movable steel plates, each of which would be far more effective against KE than a single NERA sandwich in "Chobham", but less so against CE.

So if you're already getting plenty of KE protection from the inserts themselves, it wouldn't be logical to use a thick backplate to do the same job.

55 minutes ago, SH_MM said:

The Leopard 2 could follow a similar approach, simply use a replaceable backplate (of the armor array) for easier damage repair and future upgrades. Patents from the late 1970s suggest that Germany and France prefered multi-layered backplates made out of different steel alloys and/or including non-metallic elements (e.g. glass, ceramics).

Why have a thick slab of steel in your armour cavity if you already have decent thickness steel slabs infront of it?

 

Massive oversimplification warning

Spoiler

Leo 2

https://cdn.discordapp.com/attachments/508046972075245568/565254845318299658/unknown.png

Black: armour cavity   Red: spaced steel   Purple: Rubber suspension points

M1/CR1

https://cdn.discordapp.com/attachments/508046972075245568/565255756895485967/unknown.png

Black: armour cavity   Red: steel sandwich plates  Purple: Rubber liner

I just don't see a point in having a thick steel slab in your armour cavity if there's already spaced steel plates to do it's job, but more mass efficiently.

"Chobham" as on the Mk5/2 (steel) seems a lot less "modular" than the armour of leopard 2, with the backplate being integrated into the chassis of the tank as it's part of the armour array, being the main KE protection component.

On leopard 2 it seems like the front and back plate are there for only two reasons: to protect against small arms/ light autocannon fire and to keep fragments or spalling out of the crew compartment, with the main armour being inside the cavity itself, this would allow for more adaptability/modularity.

Instead of being stuck with that heavy (and potentially soft)  backplate which can become a liability, this design allows for the armour to be consistently upgraded and kept as mass efficient as possible, with as much volume/weight put into replaceable inserts as possible, this also lends itself better to armour arrays that contain comparatively more steel than plastic/rubber, favouring KE protection over CE (which lines up with the protection requirements of leo 2).

 

The multi-layer back plate could be consistent of a HH plate on the "inside" of the cavity (facing the projectile) and then a softer plate behind that, to absorb fragments and minimise spalling, it doesn't necessarily mean it has to be thick or fully inside the cavity.

 

I guess neither of us know for sure, but considering how the Marder 1/2, Puma, Leopard 1A3/4 and leopard 2A5 all seem to use relatively thick spaced steel layers, often fairly evenly through the entire array, I reckon they did something similar on Leopard 2.

 

Just as a sidenote: the additional armour for the Mk5/2 weighed 3.8t for the skirts, 1.3t for the turret and 1.05t for the hull, at most (that includes the 40-60mm thick faceplate).

And the Marder 1A3 increased by 5.5t with it's add-on armour (for the entire vehicle), mostly consisting of steel plates on shock absorbing mounts (B&V add-on anyone?).

 

Frankly, I don't see why Germany would use "Chobham" style armour on leo 2 but use completely different technology on it's other AFVs.

 

1 hour ago, SH_MM said:

That doesn't make any sense. The document seems to list the steel plates delivered to the company responsible for welding the turret shell, not the company manufacturing the armor package. The armor technology as described by you was used in 1970-1974, the T14 mod. introduced actual composite armor including non-metallic and elastic materials (according to Krapke). Patents from the late 1970s and early 1980s suggest that Germany used NERA with a multi-layered backplate.

Hm, yes.... it may be a stretch to instantly assume same thickness of plates for the inserts, but in the interest of logistics and general armour technology they've shown in the past I think thicknesses ranging between about 5-45mm are reasonable, it's consistent with other armour types used in the 70s-90s by the BW.

Besides, composite armour doesn't have to follow the Chobham principle, it can easily consist of spaced steel plates that can move or somehow "react" to impacts, on both the Marder 1A3 and Leopard 1A1A1 they use such armour, I don't see why they wouldn't upscale it.

NERA can be anything, it doesn't have to be the same design as "Chobham", 2A5 shows that quite clearly I think.

 

1 hour ago, SH_MM said:

It's not rubber though, that's why it can be so thin.

True, I should've said plastics or polymers.... could even be something else, though I doubt it's ceramics or explosives.

Point still stands though, clearly that sandwich isn't just for CE..... unlike the early M1/CR1 NERA sandwiches that have rather thin steel covers and definitely have a different requirement.

 

I should probably clarify that I consider spaced steel armour just as much composite as "Chobham", it just has a different design.

[SH_MM]

18 hours ago, Scav said:

Everything more or less indicates that the actual NERA sandwiches themselves did very little against KE, most of the protection coming from the faceplate (around 50mm) and the backplate (80-110mm), both of which combined are already sufficient to stop 120mm APDS at ranges exceeding 1km.

The early version of the Burlingon armor was designed to provide at least the same mass efficiency of steel. Later variants tweaked for more protection against KE became available, reaching up to 1.5 mass efficiency against APDS ammunition. The version chosen for each tank concept was always based upon the weight limit and desired protection level. The Chieftain Mk. 5/2 represents an early concept, yet it already shows that Chobham/NERA modules can be very different: include or exclude the backplate. To assume that the different thickness of the back plate of the turret says anything about the exact type or composition of the internal armor array is a very questionable.

 

18 hours ago, Scav said:

And while the UK did share info with Germany, it seems rather unlikely that they would adopt the same kind of armour style as they simply had different requirements and ideas.

They had different ideas regarding armor designs when the protection requirements were different (i.e. the responsible persons in West-Germany believed that achieving sufficient protection against shaped charges was impossible and armor designs therefore weren't focused on it) -  when a requirement for protection against shaped charges was introduced, the armor arrays started to look similiar after a very short time.

Spaced armor isn't very good against shaped charges, at least not the designs optimized for protection against kinetic energy penetrators. The empty space itself barely adds any protection, in some cases - if plate thickness, warhead diameter, stand-off and empty space are in a certain ratio - it actually can lead to an improvement in penetration (see the so-called "reverse spaced armor effect"). Spaced armor optimized to defeat shaped charges consists of multiple thinner steel plates, which are all angled. When the steel plates are sloped, the crater/penetration channel created by a shaped charge jet will be assymetric,  which improves protection as the tip of the shaped charge jet is thinner than the rear section (i.e. the rear section hits the steel plate despite the fact that the tip already penetrated it.

 

Note the assymetric shape of the penetration channel.

 

Such armor is not optimal for protection against KE rounds, as the steel plates are too thin to break up the penetrators (thinner steel plates have lower TE against APFSDS rounds) and the space between the steel plates is too thin to allow fragments of the penetrator to split up or the penetrator to yaw.

This type of armor was used on the German proposals send during the Kampfpanzer 3 / Future Main Battle Tank project to the UK and represented the technology level available of anti-shaped charge armor available in West-Germany in 1970-1972 (there already had been various experiments with composite armor apparently similar to the US' siliceous-cored armor, but this type of armor wasn't very promising). Why is this interesting? Because the development of Chobham armor started exactly like that:

 

 

Thin spaced steel and aluminium plates tested as part of a fuel tank (the drawing shows "special armor number 1" of the FVRDE). The Germans also started incorporating fuel tanks into the spaced steel armor, i.e. the proposal from Krauss-Maffei had fuel as armor material in the hull. The fuel reflects shockwaves of the impact, which cause the steel plates to bulge - probably BDD with its polyurethane filler also had such a behaviour and might have inspired the development of the T-72B's NERA.

 

18 hours ago, Scav said:

IMO it's very weird if Germany would've done a 180 and adopted the UK style of composite/NERA, it seems far more likely that they simply kept working on more complex spaced armour combined with suspended or movable steel plates, each of which would be far more effective against KE than a single NERA sandwich in "Chobham", but less so against CE.

 

In your opinion West-Germany has "done a 180" in in the Kampfpanzer 3 / Future Main Battle Tank program, because they decided to adopt Chobham for the tank to be developed under the project (or rather the UK was tasked to develop a special variant of Chobham armor meeting both British and German protection requirements). Turns out that they chose the armor providing the highest level of protection.

And why should your thesis be "more likey"? You are describing a type of armor that doesn't exist ("suspended or movable steel plates"), never was made and never fielded, yet somehow you consider it to be more likely than the actual armor researched and fielded in the West during the time frame the Leopard 2 program was ongoing...

NERA was patented in Germany by Dr. Manfred Held in the early 1970s,  tested by the Franco-German Institute in Saint-Louis and a Russian book claims that a Soviet intelligence report describes an armor array tested during the Leopard 2 program consisting of five plates, four of them being NERA. The NERA was optimized for protection against KE by having thicker front plates (25 mm) made out of harder steel alloys, a design that the Soviets also fielded with the T-72B. According to Hilmes, tank concepts with NERA were created by taking spaced armor arrays and adding rubber and thin steel platess to the back of the spaced armor layers.

 

As for the armor of the Leopard 2, the level of protection against shaped charges is a lot higher than the protection requirement against KE. It's more than 50% higher, so your armor needs to have a more than 1.5 times higher mass efficiency against shaped charges than against kinetic energy penetrators. Given the estimated armor weight (assuming armor weight is evenly spread and the protection level is 400-450 mm steel-equivalent against KE for the turret front) the armor needs to reach a TE of up to 1.9 against shaped charges to stop a MILAN warhead and up to 1.25 to stop an 38 mm diameter 105 mm APFSDS KE round. As far as I know, spaced armor doesn't achieve such levels of protection, regardless of "suspended or movable plates"; but a TE of 2 against shaped charges was even reached with the early Chobham armor arrays optimized for KE protection.

 

18 hours ago, Scav said:

Why have a thick slab of steel in your armour cavity if you already have decent thickness steel slabs infront of it?

 Because it has proven to be the most efficient solution for both spaced armor vs KE and for NERA (as used on the Leopard 2) to have a thick back plate capable of absorbing the fragments of the projectile.

 

18 hours ago, Scav said:

"Chobham" as on the Mk5/2 (steel) seems a lot less "modular" than the armour of leopard 2, with the backplate being integrated into the chassis of the tank as it's part of the armour array, being the main KE protection component. 

On leopard 2 it seems like the front and back plate are there for only two reasons: to protect against small arms/ light autocannon fire and to keep fragments or spalling out of the crew compartment, with the main armour being inside the cavity itself, this would allow for more adaptability/modularity.

 

Your armor design doesn't seem to work. The rubber would likely not have any effect on protection and only be torn appart when hit. You seem to think that the shock-mounts used on the Leopard 1A1A1 and other AFVs are allowing the armor to provide more protection by moving and that the armor used on the Leopard 2 would be an extension of this concept. I don't think that this is the case - if any, the added protection will likely be really small. The interaction between projectile and armor takes place within mere split-seconds, time in which the shockwaves from the impact have to travel to the rubber and compress it, the whole armor therefore is less effective in taking the kinetic energy and diverting it back into the path of the projectile.

 

NERA also doesn't bulge before being penetrated, but only after the penetration is complete, which is why NERA (and ERA) requires a back plate to stop the tip of the shaped charge jet.

If the front plate of the Leopard 2's turret is indeed 45 mm thick, then it is thicker than the front plate of the Abrams. Why would one require such a plate to protect simple steel plates suspended via rubber against autocannons? Protecting NERA makes sense, as autocannons could damage the layers, protecting solid steel plates doesn't appear to be very senseful. How would the armor plates go back into the original position after a hit? Doesn't seem likely that such a solution would remain intact after a hit.

 

18 hours ago, Scav said:

Instead of being stuck with that heavy (and potentially soft)  backplate which can become a liability, this design allows for the armour to be consistently upgraded and kept as mass efficient as possible, with as much volume/weight put into replaceable inserts as possible, this also lends itself better to armour arrays that contain comparatively more steel than plastic/rubber, favouring KE protection over CE (which lines up with the protection requirements of leo 2).

 

The Leopard 2's armor seems to be mounted differently than the armor in the Abrams or the British concepts. Krauss-Maffei patented two solutions during the early 1970s: either having the armor in boxes/cages (similar to how the armor is mounted in the Leclerc, aside of having it inside a steel cavity) or screwing the plates onto supporting bars. The Abrams uses springs under tension to hold the NERA plates (at least in the original model), which doesn't seem to favor heavier plates  (also the Abrams was made to be cheap/affordable with a lower requirement for KE protection, hence using multi-layered backplates and/or HHS wasn't necessarily required/favored). The Challenger 1 wasn't originally designed to be a high quality tank with thick armor (when it was still the Shir 2), it only was altered in the 1980s with minimum changes to the overall design.

 

18 hours ago, Scav said:

I guess neither of us know for sure, but considering how the Marder 1/2, Puma, Leopard 1A3/4 and leopard 2A5 all seem to use relatively thick spaced steel layers, often fairly evenly through the entire array, I reckon they did something similar on Leopard 2.

 

The choice for a specific one of multiple possible armor types is the result of the protection requirements. The MBT-70, Marder 1A3, Leopard 1A3, 1A4 and 1A1A1 were all designed with protection against bullet-shaped, spin-stabilized AP, APCR and/or APDS rounds as requirement - there was no requirement for protection against APFSDS ammunition or shaped charge warheads (not even against the RPG-7). Against these types of threats, simple spaced armor with high-hardness outer plate is extremely effective, as the fragments of the round will easily spread along a greater surface area due to the spin of the round. This is also why the NATO heavy tripple target proved to be so hard to defeat for APDS rounds.

 

APFSDS ammo is not spin-stabilized and requires armor to work differently if one desires efficient protection. A further stage - the disturber - has to be added to spread the fragments of the round, otherwise even the fragements of a broken long-rod penetrator will impact nearly on the same spot. NERA (of sufficient thickness) seems to be a good solution, as the bulging of the interlayer material will impede a lateral force upon the fragments, throwing them into different trajectories.

 

 

The Marder 2 and the Boxer rely on ceramic armor whereever possible. The spaced armor is only used in the frontal slope area, where ceramic is less efficient (due to the shattering of ceramic tiles negating the gain in LOS from sloping the frontal armor). Here the requirement is again protection against bullet-shaped, spin-stabilized rounds one of the main goals, but while also considering protection against some types of medium caliber APFSDS ammo. These rounds usually have not been optimized to defeat multi-layered armor and rely on more brittle/denser alloys to maximize performance against homogenous steel armor (at least Rheinmetall claimed that the 30 mm APFSDS developed for the Puma was unique in being optimized for use against multi-layered targets).

 

The  Puma's NERA is not using particular thick steel plates. It seems to be an one to one to one ratio between steel plates and interlayer material, which is pretty standard and shows that the armor array is primarily optimized against shaped charge warheads, which isn't surprising given the large disparity in penetration power between medium caliber rounds (30-40 mm APFSDS: 100-150 mm steel at 1,000 m distance) and RPGs (300-700 mm steel).

 

 

The Leopard 2A5's armor isn't really comparable, as the solution doesn't appear to be suitable for internal armor arrays. It is also armor designed a decade after the Leopard 2, not really relevant for the discussion.

 

18 hours ago, Scav said:

And the Marder 1A3 increased by 5.5t with it's add-on armour (for the entire vehicle), mostly consisting of steel plates on shock absorbing mounts (B&V add-on anyone?). 

 

The larger weight of the add-on armor for the Marder is the result of the greater surface area covered. For the MBT-80, one proposal included add-on armor (just covering the sides) weighing more than 5.5 metric tons. The Marder 1A3's armor is designed to defeat a similar type of threat as the add-on armor fielded on the Leopard 1A1A1, hence the similar design.

 

The second generation of add-on armor by Blohm & Voss looked a lot different, as this was designed to protect against shaped charges and APFSDS rounds:

 

 

Protection against RPG-7 up to an side angle of 45° (Leopard 1A6 prototype)  or up to 90° (SuperM48) was achieved. Turret front was resistant to an unspecified Soviet 125 mm APFSDS round at 1,500 m.

 

18 hours ago, Scav said:

Frankly, I don't see why Germany would use "Chobham" style armour on leo 2 but use completely different technology on it's other AFVs.

Because the other AFVs are designed to defeat other threats? The Leopard 2 is the only mentioned vehicle (aside of the Puma IFV) designed with a protection requirement against APFSDS rounds and shaped charges, hence the armor used on it looks different. It has been described as NERA ("armor with elastic materials", "Beulblechpanzerung", etc.) by many authors and the connection to the cooperation with Great Britian, the NERA tested by the Franco-German institute in Saint-Louis and Dr. Manfred Held are known examples of NERA being related to the Leopard 2 program.

 

NERA is not ideal for protecting against kinetic energy penetrators, therefore it offers no advantage when no reference threat with a shaped charge warhead is specified. To break a projectile, you'll need NERA with a similar amount of steel as the face-plate of a simpler, cheaper and more durable spaced armor solution as fielded on the Marder 1A3.

 

The Bradley was fitted with steel plates bolted ontop of its aluminium structure during the M2A2/M3A2 upgrade - not with NERA, not with DU. Does this mean that the armor fitted to the M1A1 (HA) Abrams is pure steel armor? The Stryker is fitted with ceramic armor, again there is no NERA. The British Warrior IFV was fitted with NERA, as there was a protection requirement against shaped charges, but not much of a requirement for protection against kinetic energy rounds.

 

18 hours ago, Scav said:

Hm, yes.... it may be a stretch to instantly assume same thickness of plates for the inserts, but in the interest of logistics and general armour technology they've shown in the past I think thicknesses ranging between about 5-45mm are reasonable, it's consistent with other armour types used in the 70s-90s by the BW.

 

The Leopard 2K utilized 50 and 84 mm steel plates as part of its frontal armor. The MBT-70 had a 130 mm cast base-plate (not including slope).

 

18 hours ago, Scav said:

Besides, composite armour doesn't have to follow the Chobham principle, it can easily consist of spaced steel plates that can move or somehow "react" to impacts, on both the Marder 1A3 and Leopard 1A1A1 they use such armour, I don't see why they wouldn't upscale it.

 

The movement of the shock-mounted armor seems to play only a little or no role at all in terms of armor protection. The armor has been said to follow the Chobham principle by German sources and also was optimized for protection against shaped charges.

 

Engineers all over the world faced the same problem: how to implement an efficient protection solution against shaped charges (that is also cheap and has decent multi-hit capability). All over the world this resulted in NERA, most of which has the form of bulging plates armor (spaced multi-layered plates with an expanding/elastic interlayer material). The Brits developed such a type of armor, the Iraqis developed such a type of armor, the Indians developed such a type of armor, the Soviets developed such a type of armor, the Israeli developed such a type of armor, the Chinese developed such a type of armor, ...

 

... but for some reasons West-Germany, despite being known to have tested NERA designs in the relevant time frame opted against using it? Unlikely.

 

18 hours ago, Scav said:

Point still stands though, clearly that sandwich isn't just for CE..... unlike the early M1/CR1 NERA sandwiches that have rather thin steel covers and definitely have a different requirement.

 

Have you ever seen the Challenger 1's NERA sandwiches? I haven't, but given the proclaimed protection level and that its special armor modules are heavier than that of the Abrams, I would be very surprised if it is identical in design. The Challenger 1 supposeldy reaches 500 mm steel-equivalent protection vs KE on the turret, but only 700 mm vs shaped charges - not a comparable ratio to the Abrams.

 

 

 

[Ramlaen]

 

[Scav]

On 4/10/2019 at 10:05 AM, SH_MM said:

The early version of the Burlingon armor was designed to provide at least the same mass efficiency of steel. Later variants tweaked for more protection against KE became available, reaching up to 1.5 mass efficiency against APDS ammunition. The version chosen for each tank concept was always based upon the weight limit and desired protection level. The Chieftain Mk. 5/2 represents an early concept, yet it already shows that Chobham/NERA modules can be very different: include or exclude the backplate. To assume that the different thickness of the back plate of the turret says anything about the exact type or composition of the internal armor array is a very questionable.

I'm talking specifically about the ones they tested on Chieftain Mk5/2, Shir 2 and their proposals for MBT-80.

The later versions that were optimised against KE quite significantly dropped in CE protection, MBT-80 specifically was originally required to protect against 430mm KE and 580mm CE, but they changed this requirement to 405mm KE and 850mm CE later on.

It's important to note that Chobham was mostly tested against APDS and not APFSDS.

 

Regarding the inclusion of a backplate, this was mostly done on the frontal armour where it would be easy to install the composite ontop of existing armour plates or make it easier to integrate, for the sides the backplate was often dropped due to different requirement (side composite was mostly for RPGs and light autocannons, don't need backplates for that) and simply not being practical.... 
They already found that splitting the skirts up into 18 different sections would make them impractical to handle and install by the crew alone, so they went with larger 4 section skirts instead, but that would still not make it practical to include a thick backplate as it would make the tank even wider an substantially heavier.

Taking that into account, I think the backplate is a somewhat decent indicator to the internal armour array, if there isn't a thick backplate, it means the inserts themselves are considered good enough for KE or that it's simply impractical/not needed to have a thick backlayer.

Then you can see where the armour is located, what the expected threats would be and make an educated guess as to what the internal array most probably looks like (in very basic terms).

 

On 4/10/2019 at 10:05 AM, SH_MM said:

They had different ideas regarding armor designs when the protection requirements were different (i.e. the responsible persons in West-Germany believed that achieving sufficient protection against shaped charges was impossible and armor designs therefore weren't focused on it) -  when a requirement for protection against shaped charges was introduced, the armor arrays started to look similiar after a very short time.

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.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

Spaced armor isn't very good against shaped charges, at least not the designs optimized for protection against kinetic energy penetrators. The empty space itself barely adds any protection, in some cases - if plate thickness, warhead diameter, stand-off and empty space are in a certain ratio - it actually can lead to an improvement in penetration (see the so-called "reverse spaced armor effect"). Spaced armor optimized to defeat shaped charges consists of multiple thinner steel plates, which are all angled. When the steel plates are sloped, the crater/penetration channel created by a shaped charge jet will be assymetric,  which improves protection as the tip of the shaped charge jet is thinner than the rear section (i.e. the rear section hits the steel plate despite the fact that the tip already penetrated it.

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.

Systems like the B&V add-on is what I'm referring to.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

Such armor is not optimal for protection against KE rounds, as the steel plates are too thin to break up the penetrators (thinner steel plates have lower TE against APFSDS rounds) and the space between the steel plates is too thin to allow fragments of the penetrator to split up or the penetrator to yaw.

This type of armor was used on the German proposals send during the Kampfpanzer 3 / Future Main Battle Tank project to the UK and represented the technology level available of anti-shaped charge armor available in West-Germany in 1970-1972 (there already had been various experiments with composite armor apparently similar to the US' siliceous-cored armor, but this type of armor wasn't very promising). Why is this interesting? Because the development of Chobham armor started exactly like that:

Yes, and it seems they (UK) kept this design and refined it by adding plastics or rubber to the rear of the steel plates.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The Germans also started incorporating fuel tanks into the spaced steel armor, i.e. the proposal from Krauss-Maffei had fuel as armor material in the hull. The fuel reflects shockwaves of the impact, which cause the steel plates to bulge - probably BDD with its polyurethane filler also had such a behaviour and might have inspired the development of the T-72B's NERA.

Yeah, they use this for the side hull, didn't seem optimal for the front hull apparently.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

In your opinion West-Germany has "done a 180" in in the Kampfpanzer 3 / Future Main Battle Tank program, because they decided to adopt Chobham for the tank to be developed under the project (or rather the UK was tasked to develop a special variant of Chobham armor meeting both British and German protection requirements). Turns out that they chose the armor providing the highest level of protection.

And why should your thesis be "more likey"? You are describing a type of armor that doesn't exist ("suspended or movable steel plates"), never was made and never fielded, yet somehow you consider it to be more likely than the actual armor researched and fielded in the West during the time frame the Leopard 2 program was ongoing...

Never seen much info at all on the Kampfpanzer 3, most books just mention it in passing so it doesn't appear that important.

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.
When comparing the additional armour of the Marder 1A3 and Warrior for instance, they're completely different, the latter featuring skirts that are essentially thin boxes with thin angled plates on the inside (probably with a much bigger rubber plate attached to each steel one).

 

Not saying leopard 2 doesn't feature NERA, just not the kind as seen in the Mk5/2 program, but they definitely thought differently than both the US and UK, otherwise they would've come up with a similar MBT design and the US wouldn't have commented that the 2AV had "inferior" armour.

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.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

 Because it has proven to be the most efficient solution for both spaced armor vs KE and for NERA (as used on the Leopard 2) to have a thick back plate capable of absorbing the fragments of the projectile.

Only for two layer spaced armour though, with multiple layers this isn't the case, as seen on the Russian T-series that went for more, medium thickness steel plates with small airgaps or textolite

Sure, if you don't have very much steel and space between the first and last layer, a thick plate makes sense, otherwise it seems better to more evenly distribute the same steel thickness over a larger space.

 

Brits used it as their NERA sandwiches in comparison didn't contain much steel (as proposed on Mk5/2).

 

On 4/10/2019 at 10:05 AM, SH_MM said:

Your armor design doesn't seem to work. The rubber would likely not have any effect on protection and only be torn appart when hit. You seem to think that the shock-mounts used on the Leopard 1A1A1 and other AFVs are allowing the armor to provide more protection by moving and that the armor used on the Leopard 2 would be an extension of this concept. I don't think that this is the case - if any, the added protection will likely be really small. The interaction between projectile and armor takes place within mere split-seconds, time in which the shockwaves from the impact have to travel to the rubber and compress it, the whole armor therefore is less effective in taking the kinetic energy and diverting it back into the path of the projectile.

It was an oversimplified representation, it doesn't have to be exactly like that.

I was trying to point out the general layout and difference in steel/rubber concentration.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

NERA also doesn't bulge before being penetrated, but only after the penetration is complete, which is why NERA (and ERA) requires a back plate to stop the tip of the shaped charge jet.

If the front plate of the Leopard 2's turret is indeed 45 mm thick, then it is thicker than the front plate of the Abrams. Why would one require such a plate to protect simple steel plates suspended via rubber against autocannons? Protecting NERA makes sense, as autocannons could damage the layers, protecting solid steel plates doesn't appear to be very senseful. How would the armor plates go back into the original position after a hit? Doesn't seem likely that such a solution would remain intact after a hit.

30-45mm thick, making sure autocannons simply don't affect the internal armour plates as that might require replacing them, which could be more expensive than replacing the outer plate.
There's a variety of reasons why you wouldn't want autocannons to impact the internal armour, it might consist of very high hardness steel, have attachment points throughout which can be damaged, increased efficiency against LRPs.....

 

The Russians do it, and they used armour arrays that wouldn't be affected much if at all by autocannons penetrating the first layer.

It seems a first layer of 1-2 penetrator diameters is optimal against LRPs, even more reason to make the first layer between 30-60mm.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The Leopard 2's armor seems to be mounted differently than the armor in the Abrams or the British concepts. Krauss-Maffei patented two solutions during the early 1970s: either having the armor in boxes/cages (similar to how the armor is mounted in the Leclerc, aside of having it inside a steel cavity) or screwing the plates onto supporting bars. The Abrams uses springs under tension to hold the NERA plates (at least in the original model), which doesn't seem to favor heavier plates  (also the Abrams was made to be cheap/affordable with a lower requirement for KE protection, hence using multi-layered backplates and/or HHS wasn't necessarily required/favored). The Challenger 1 wasn't originally designed to be a high quality tank with thick armor (when it was still the Shir 2), it only was altered in the 1980s with minimum changes to the overall design.

Yes, I agree.
This would indicate the individual layers are thicker and heavier on leopard 2 as opposed to M1, I personally think this is due to there being more steel and less rubber/plastics.

Also, those mounting systems could just be for the entire array, not the individual sections.

Having the individual sections a little bit smaller and with some kind of shock absorbing system between them, could definitely help (although not nearly as much as traditional NERA would, as you pointed out).

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The choice for a specific one of multiple possible armor types is the result of the protection requirements. The MBT-70, Marder 1A3, Leopard 1A3, 1A4 and 1A1A1 were all designed with protection against bullet-shaped, spin-stabilized AP, APCR and/or APDS rounds as requirement - there was no requirement for protection against APFSDS ammunition or shaped charge warheads (not even against the RPG-7). Against these types of threats, simple spaced armor with high-hardness outer plate is extremely effective, as the fragments of the round will easily spread along a greater surface area due to the spin of the round. This is also why the NATO heavy tripple target proved to be so hard to defeat for APDS rounds.

Yes, though it's not unreasonable to think increasing the amount of plates and overal thickness of the array could make it work quite well against APFSDS, especially early ones.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

APFSDS ammo is not spin-stabilized and requires armor to work differently if one desires efficient protection. A further stage - the disturber - has to be added to spread the fragments of the round, otherwise even the fragements of a broken long-rod penetrator will impact nearly on the same spot. NERA (of sufficient thickness) seems to be a good solution, as the bulging of the interlayer material will impede a lateral force upon the fragments, throwing them into different trajectories.

This can still be achieved by relatively simple spaced armour with multiple layers.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The Marder 2 and the Boxer rely on ceramic armor whereever possible. The spaced armor is only used in the frontal slope area, where ceramic is less efficient (due to the shattering of ceramic tiles negating the gain in LOS from sloping the frontal armor).

I keep hearing about ceramics, but never saw any conclusive proof of their use in western MBTs (I'm also excluding Kvarts or similar fillers) and according to Lindstöm the Swedes tested several ceramics and found them quite lacklustre.

Authors like to bring it up.... but apart from that....

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The  Puma's NERA is not using particular thick steel plates. It seems to be an one to one to one ratio between steel plates and interlayer material, which is pretty standard and shows that the armor array is primarily optimized against shaped charge warheads, which isn't surprising given the large disparity in penetration power between medium caliber rounds (30-40 mm APFSDS: 100-150 mm steel at 1,000 m distance) and RPGs (300-700 mm steel).

As you say yourself, large difference of medium caliber APFSDS and HEAT rounds is the primary reason.

Still, one to one is quite different from the ratios seen in US/UK Chobham armour schemes, those usually feature less steel comparatively (on the M1 the layers are also quite thin). 

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The Leopard 2A5's armor isn't really comparable, as the solution doesn't appear to be suitable for internal armor arrays. It is also armor designed a decade after the Leopard 2, not really relevant for the discussion.

But it shows that even for their more CE focussed armour designs, they feature relatively thick steel layers (all in comparison with M1/CR1), indicating that internal armour (which is quite likely to be mounted vertically) is less effective against CE and more effective against KE.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The larger weight of the add-on armor for the Marder is the result of the greater surface area covered. For the MBT-80, one proposal included add-on armor (just covering the sides) weighing more than 5.5 metric tons. The Marder 1A3's armor is designed to defeat a similar type of threat as the add-on armor fielded on the Leopard 1A1A1, hence the similar design.

Dunno, I think hull front + full sides + turret front and sides is even larger area than the add-on for the Marder which is mainly on the front hull and upper side hull (also on the turret, though it's relatively small), and the add-on for the Mk5/2 is substantially thicker....

 

On 4/10/2019 at 10:05 AM, SH_MM said:

Protection against RPG-7 up to an side angle of 45° (Leopard 1A6 prototype)  or up to 90° (SuperM48) was achieved. Turret front was resistant to an unspecified Soviet 125 mm APFSDS round at 1,500 m.

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

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

(granted it's still quite good protection)

 

On 4/10/2019 at 10:05 AM, SH_MM said:

Because the other AFVs are designed to defeat other threats? The Leopard 2 is the only mentioned vehicle (aside of the Puma IFV) designed with a protection requirement against APFSDS rounds and shaped charges, hence the armor used on it looks different. It has been described as NERA ("armor with elastic materials", "Beulblechpanzerung", etc.) by many authors and the connection to the cooperation with Great Britian, the NERA tested by the Franco-German institute in Saint-Louis and Dr. Manfred Held are known examples of NERA being related to the Leopard 2 program.

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?

 

On 4/10/2019 at 10:05 AM, SH_MM said:

NERA is not ideal for protecting against kinetic energy penetrators, therefore it offers no advantage when no reference threat with a shaped charge warhead is specified. To break a projectile, you'll need NERA with a similar amount of steel as the face-plate of a simpler, cheaper and more durable spaced armor solution as fielded on the Marder 1A3.

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

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The Bradley was fitted with steel plates bolted ontop of its aluminium structure during the M2A2/M3A2 upgrade - not with NERA, not with DU. Does this mean that the armor fitted to the M1A1 (HA) Abrams is pure steel armor? The Stryker is fitted with ceramic armor, again there is no NERA. The British Warrior IFV was fitted with NERA, as there was a protection requirement against shaped charges, but not much of a requirement for protection against kinetic energy rounds.

They didn't have a CE requirement for Bradley, wouldn't make sense to fit it with NERA, and DU would've been completely off the table anyway.

Wasn't Stryker fitted with MEXAS of some type, to protect against 14.5s? That's quite different from 30mm autocannons.

As for Warrior, yeah, and Leopard 2 didn't have that much of a CE requirement either (atleast compared to M1 or CR1).

Especially if we assume that it's KE protection is around 430mm and CE is around 600-650mm, that's a very different ratio than M1 or CR1 (both around 2:1 CE to KE).

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The Leopard 2K utilized 50 and 84 mm steel plates as part of its frontal armor. The MBT-70 had a 130 mm cast base-plate (not including slope).

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.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

The movement of the shock-mounted armor seems to play only a little or no role at all in terms of armor protection. The armor has been said to follow the Chobham principle by German sources and also was optimized for protection against shaped charges.

 

Engineers all over the world faced the same problem: how to implement an efficient protection solution against shaped charges (that is also cheap and has decent multi-hit capability). All over the world this resulted in NERA, most of which has the form of bulging plates armor (spaced multi-layered plates with an expanding/elastic interlayer material). The Brits developed such a type of armor, the Iraqis developed such a type of armor, the Indians developed such a type of armor, the Soviets developed such a type of armor, the Israeli developed such a type of armor, the Chinese developed such a type of armor, ...

 

... but for some reasons West-Germany, despite being known to have tested NERA designs in the relevant time frame opted against using it? Unlikely.

It took the Russians until the T-72B to use it in turrets, and until T-90 for the hull.

In both instances, they used it as little as possible or with a much higher steel to rubber ratio.

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.

 

On 4/10/2019 at 10:05 AM, SH_MM said:

Have you ever seen the Challenger 1's NERA sandwiches? I haven't, but given the proclaimed protection level and that its special armor modules are heavier than that of the Abrams, I would be very surprised if it is identical in design. The Challenger 1 supposeldy reaches 500 mm steel-equivalent protection vs KE on the turret, but only 700 mm vs shaped charges - not a comparable ratio to the Abrams.

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 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).

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 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.

That new doc also says it can defeat 125-150mm HEAT warheads, same as Mk5/2 (those were rated at 711mm of penetration), so only 700mm against CE seems rather low.

Especially if we take into consideration that newer HEAT warhead manufacturing led to higher penetration with same diameter warheads.

 

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).

The MBT-80 was considered to have superior protection and was a much more ambitious design, when it failed, I doubt that they somehow managed to put better armour than MBT-80 was intended to have, on the CR1 (which had the same armour thickness as Shir 2 mind you).

 

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.

Furthermore, that document has a lot of weirdness about it:

Spoiler

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?
Despite said tank supposedly having 500mm KE on both hull and turret?
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.

 

There's so much inconsistency in this document that I would take the "500mm KE" with a big grain of salt.

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

But 500mm KE against M829? Or even L23A1?
Doesn't seem likely.

 

 

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.

 

 

Edit: I should clarify that I think leopard 2 armour is probably somewhere between leopard 1A3 and M1/CR1 in design.

[Wiedzmin]

On 4/9/2019 at 9:21 PM, SH_MM said:

 

Well,

 

100mm/70deg - 3057meters

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

 

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