Main Battle Tanks and Armour Technology

[Sovngard]

Are we sure that the Soviet T-72A uses the same armor package as its export counterpart ; the T-72M1 ?

 

[militarysta]

Are we sure that the Soviet T-72A uses the same armor package as its export counterpart ; the T-72M1 ?

Preatty sure yes.
But they are some unclera thinks yet...

For example: added external HHS plate was 16mm in T-72M1, and...18mm in T-80B, and there is some propability that this plate was thicker in some version, or it was mounted whit air gap between itsel and first armour plate.

 

[Sovngard]

T-72M1 armour layout:

turret:

Protection for 0. degree (530mm LOS):
410-420mm RHA vs APFSDS
500mm RAH vs HEAT

for 30. degree protection is mucht smaller of course...

Finally, my vision of the kvartz, sand rods, sandbar (whatever you call it) was not too far from the reality.

http://defenceforumindia.com/forum/land-forces/208-main-battle-tanks-armour-technology-460.html#post866366


IMHO, it's a very primitive but cheap composite armor package. Even the BDD armor seems to be more sophisticated.

I expected more from the Soviet engineering, especially for the T-80B which is finally fitted with the same armor package as the T-72A.

This was my evening rant.

 

[Damian]

Meanwhile, USa and UK will send to Poland two battalion sized armored units. As I had opportunity to recently sit inside Leopard 2 series, I will also try to sit inside M1A2SEPv2 and Challenger 2 tanks if only I will be able to get in to the proving grounds area, perhaps there will be some sort of open day for civilians with vehicles display.

 

[asianobserve]

Putin Arouses European Tank Ambitions Dormant Since Cold War - Bloomberg

The Ukraine crisis is pushing European governments to review the role of the weapon that dominated Cold War defenses as the strength of Russian ground forces stirs political concerns: the battle tank.

 

[militarysta]

@UP
nothing new, in Poland clever poples NEVER decrease role of the tanks in Land Forces...
Mostly - to close to estern countries whit signifiant tank potential.
While Belarusian and Ukrinian armed forces become to be a "paper tiger" then russian ones are serious thread...

 

[militarysta]

Finally, my vision of the kvartz, sand rods, sandbar (whatever you call it) was not too far from the reality.

IMHO, it's a very primitive but cheap composite armor package. Even the BDD armor seems to be more sophisticated.

I expected more from the Soviet engineering, especially for the T-80B which is finally fitted with the same armor package as the T-72A.

This was my evening rant.

Well, more or less we should notic the whole picture not only one puzzle ;-) Maybe it was primitive but 200mm cast steel + 130mm kvartz + 200mm cast steel give circa:
410-420mm RHA vs APFSDS and almoust
500mm vs HEAT.
In erly 1980s it was nice value.
Moret sophisticated and mucht more expensive T-64B whit corund balls placed in aluminia filter had not much better protection valuse:
420-450mm RHA vs APFSDS
550mm RHA vs HEAT

But yes - western style "Bulrington" was mucht more spohisticated -based on NERA/NxRA principles - and while it was offered simmilar vs KE value then Burlington offer mucht better protection vs SC (CE) warhed. Unable to achive on the est without ERA.

 

[Damian]

I would be carefull about speculating about what protection initial "Burlington" variants offered.

Actually I read again Richard P. Hunnicutt book Abrams A History Of The American Main Battle Tank volume 2 and found something interesting. Hunnicutt writes about XM1 protection requirements for the front against 115mm APFSDS from 800m, but not in the context of "Burlington" special armor! This requirement actually comes from pre "Burlington" use! The whole requirement is based on protection capabilities of earlier special armor designs made by Ballistic Research Laboratory for initial vehicle concepts like LK 10322 so even pre real XM1 program.

The real requirements for XM1/M1 protection with "Burlington" armor package is actually classified and have nothing to do with pre XM1 vehicle concepts after MBT-70 and XM803 cancellation.

Actually vehicle concepts like LK 10322 were considered to also have simple spaced armor and not special armor. So this is where the story about ~400mm vs APFSDS requirement comes from, but have nothing in common with the XM1/M1 and it's series manufactured "Burlington" armor.

Keep this in mind, and this actually shows how important is to carefully read sources.

 

[Sovngard]

On the page 168, they also talk about steel-glass-steel armor arrays and multiple steel and aluminum plates combinations developed by the Ballistic Research Laboratory in 1972.

The BRL was not idle at that time.

Does these shapes sound familiar ?

 

[methos]

I would be carefull about speculating about what protection initial "Burlington" variants offered.

Actually I read again Richard P. Hunnicutt book Abrams A History Of The American Main Battle Tank volume 2 and found something interesting. Hunnicutt writes about XM1 protection requirements for the front against 115mm APFSDS from 800m, but not in the context of "Burlington" special armor! This requirement actually comes from pre "Burlington" use! The whole requirement is based on protection capabilities of earlier special armor designs made by Ballistic Research Laboratory for initial vehicle concepts like LK 10322 so even pre real XM1 program.

The real requirements for XM1/M1 protection with "Burlington" armor package is actually classified and have nothing to do with pre XM1 vehicle concepts after MBT-70 and XM803 cancellation.

Actually vehicle concepts like LK 10322 were considered to also have simple spaced armor and not special armor. So this is where the story about ~400mm vs APFSDS requirement comes from, but have nothing in common with the XM1/M1 and it's series manufactured "Burlington" armor.

Keep this in mind, and this actually shows how important is to carefully read sources.

Sorry to destory your dreams, but that the XM1/M1 Abrams was designed with protection against 115 mm APFSDS "only" has been confirmed by two other sources. You should also read the whole chapter in Hunnicutt's book. The TACOM studies served as base of the requirements for the XM1 tank; the studies with spaced/simple laminate armour weren't able to meet the weight requirements. LK 10382 is from March 1973, in early July 1973 the Americans visited the Chobham facilities to gain full access to Burlington armour and in January 1974 both GM and Chrysler had their prototypes redesigned with Chobham armour. Pretty short time for making completely knew requirements...

Chobham was adopted because it was able to meet the weight requirements, which was impossible for even the last TACOM study LK 10382 (planned was 58 tons, but more than 60 tons weight were needed to reach the protection level) - even for this the LK 10382 had to make huge cuts (less hull armour, only 300 gallons of fuel, smaller turret ring diameter, shorter hull) which all are not found on the XM1 with Burlington armour.

 

[Damian]

Sorry to destory your dreams, but that the XM1/M1 Abrams was designed with protection against 115 mm APFSDS "only" has been confirmed by two other sources. You should also read the whole chapter in Hunnicutt's book. The TACOM studies served as base of the requirements for the XM1 tank; the studies with spaced/simple laminate armour weren't able to meet the weight requirements. LK 10382 is from March 1973, in early July 1973 the Americans visited the Chobham facilities to gain full access to Burlington armour and in January 1974 both GM and Chrysler had their prototypes redesigned with Chobham armour. Pretty short time for making completely knew requirements...

Chobham was adopted because it was able to meet the weight requirements, which was impossible for even the last TACOM study LK 10382 (planned was 58 tons, but more than 60 tons weight were needed to reach the protection level) - even for this the LK 10382 had to make huge cuts (less hull armour, only 300 gallons of fuel, smaller turret ring diameter, shorter hull) which all are not found on the XM1 with Burlington armour.

Read again Hunnicutt's book. It is very clearly written there about requirements prior transfer of technology of the "Burlington" armor to the US and integration of it with the final XM1 prototypes. There is nothing about protection levels required or achieved after this.

Of course you have full right to believe in whatever you wish to believe, but the logical conclusion is very clear.

And mind also, that your other sources, might be confused about initial requirements which are known, but requirements or achieved levels of protection after "Burlington" integration are still classified, so they preatty much assume something based on old data.

Oh and by the way, for you this is short time to modify (not create new) requirements? You won't believe how quickly requirements can be modified.

Not to mention that during development stage, it was clearly said to the decision makers that or they will lower protection requirements, or create less restrictive weight requirements for vehicle weighting above 50 tons. There is even said in the book that designers could not keep in pace with BRL releasing rapidly newer and newer armor designs, so design teams were not able to integrate new armor designs in to vehicle design and calculate weight to protection ratio on time back then. So development was very quick with rapid changes in design.

I strongly recommend to read Hunnicutt's book again, with understanding.

 

[methos]

It is very clearly written there about requirements prior transfer of technology of the "Burlington" armor to the US and integration of it with the final XM1 prototypes. There is nothing about protection levels required or achieved after this.

Exactly. Hunnicutt, one of the authors who does mention every single detail in his book, forgot to mention that the protection levels were increased.

Of course you have full right to believe in whatever you wish to believe, but the logical conclusion is very clear.

Yes, the logical conclusion is very clear. Please take of your M1 Abrams fanboy badge for a moment and think about it logically:

Please compare LK 10382 concept to the serial tank: The Lk 10382 carries 205 gallons (776 l) less fuel, it does have a two inch smaller turret diameter, it has reduced hull armour not meeting the protection requirements, it doesn't have isolated ammo stowage, carries a reduced amount of main gun ammunition, it doesn't have armoured side skirts (or any at all) and has nearly no turret bustle. And you want to suggest that the weight savings from using Burlington composite armour were all used to increase armour protection...
The LK 10382 concept was designed to meet very strict weight limits which were technological impossible, so the concept was cut-down on a large number of features (and still not able to meet the requirements). After visiting the Chobham facilities to gain full access to Burlington armour, the XM1 was redesgined and the freed up weight was used to replace all cut-down features with fully-fledged ones.

The Brittons designed the Chieftain Mk 5/2 tank with a slightly higher protection requirement (frontal armour vs 115 mm APFSDS from 200 m distance). The shell made of Aluminium instead of steel in order to save several tons of weight, while the tank was considerable smaller than the XM1 and used lighter components. Still the calculated the weight of the Chieftain Mk 5/2 tank to be above the weight of the XM1 prototypes.

Against what should the protection be designed in 1974? The T-72 and the T-64A were unknown to Western intelligence, so the 115 mm gun was the most potent threat known to NATO. The TACOM studies served as base for the Army's requirements and not as a cheap alternative based on lower requirement.

Your claims that the armour protection was increased is mere speculation without any sources or facts supporting it. In the same way your claims that all other authors stating that the XM1's armour was designed vs 115 mm APFSDS might have used outdated sources is mere speculation without any sources or facts supporting it.

Oh and by the way, for you this is short time to modify (not create new) requirements? You won't believe how quickly requirements can be modified.

Modifiying the protection requirements means a complete redesign of the vehicle. Adopting the U.S. requirements for protection took more thna a year for the Leopard 2 despite the turret T14 already meeting them.

 

[Damian]

Exactly. Hunnicutt, one of the authors who does mention every single detail in his book, forgot to mention that the protection levels were increased.

Or he could not mention it. I hope you understand that when you work very closely on your book to the army or goverment sources, you can't say about everything. Look at Marsh Gelbart books, he knows a lot of classified stuff about Merkava, which does not mean he will share this knowledge in his books, simply because he have agreement with Israelis, he can know more, but he can't share.

Yes, the logical conclusion is very clear. Please take of your M1 Abrams fanboy badge for a moment and think about it logically:

Call me a fanboy once more and I end any discussion with you.

Please compare LK 10382 concept to the serial tank: The Lk 10382 carries 205 gallons (776 l) less fuel, it does have a two inch smaller turret diameter, it has reduced hull armour not meeting the protection requirements, it doesn't have isolated ammo stowage, carries a reduced amount of main gun ammunition, it doesn't have armoured side skirts (or any at all) and has nearly no turret bustle. And you want to suggest that the weight savings from using Burlington composite armour were all used to increase armour protection...

Yes, because I don't know, neither do you, efficency of "Burlington" armor variant used in original M1, it's all classified, but not immposible.

The LK 10382 concept was designed to meet very strict weight limits which were technological impossible, so the concept was cut-down on a large number of features (and still not able to meet the requirements). After visiting the Chobham facilities to gain full access to Burlington armour, the XM1 was redesgined and the freed up weight was used to replace all cut-down features with fully-fledged ones.

And M1's weight increased over original requirements for new tank weight.

The Brittons designed the Chieftain Mk 5/2 tank with a slightly higher protection requirement (frontal armour vs 115 mm APFSDS from 200 m distance). The shell made of Aluminium instead of steel in order to save several tons of weight, while the tank was considerable smaller than the XM1 and used lighter components. Still the calculated the weight of the Chieftain Mk 5/2 tank to be above the weight of the XM1 prototypes.

Chieftain uses heavier suspension than M1. To compare vehicles through weight you need to take in to account all it's components. Oh and one more thing, Chieftain Mk5/2 have additional special armor over hull sides.

Against what should the protection be designed in 1974? The T-72 and the T-64A were unknown to Western intelligence, so the 115 mm gun was the most potent threat known to NATO. The TACOM studies served as base for the Army's requirements and not as a cheap alternative based on lower requirement.

The 125mm guns at that time had comparable anti armor eficency as 115mm.

3BM28 115mm APFSDS from 1978 have comparable penetration capability to 3BM22 125mm APFSDS from 1976, which was main APFSDS type used by the Soviet Army even trhough the 1980's.

Preatty much the basic M1 was well proteced at the front against both 115mm smoothbore and 125mm smoothbore even up to 1985, and after 1985 M1IP and basic M1A1 were still preatty much invurnable to the 125mm APFSDS ammo used by Soviets back then.

So yeah, talking that M1's armor was good enough only to protect against 115mm APFSDS from 800mm is a nonsense.

Your claims that the armour protection was increased is mere speculation without any sources or facts supporting it. In the same way your claims that all other authors stating that the XM1's armour was designed vs 115 mm APFSDS might have used outdated sources is mere speculation without any sources or facts supporting it.

Yeah, right, as far as I can see, most of so called "speculations" done by me end up as accurate or very close to reality observations.

Modifiying the protection requirements means a complete redesign of the vehicle. Adopting the U.S. requirements for protection took more thna a year for the Leopard 2 despite the turret T14 already meeting them.

You obviously never had any closer experience with military requirements and how quickly these can be modified.

 

[Damian]

Oh and BTW, actually Hunnicutt mentions that during M1 development, survivability was somehow enhanced by changes to the design. It was during FSED phase of development program, so we can assume that during development, there were constant changes to the vehicle design, and we can actually seen this between early prototypes and both FSED prototypes.

 

[methos]

Or he could not mention it. I hope you understand that when you work very closely on your book to the army or goverment sources, you can't say about everything.

He could have stated that the armour was increased to classified levels, just like pretty much all other authors write about armour protection increasements. He didn't wrote anything about thicker or better armour. By your logic, we also could say that the protection requirements could have been decreased, because he doesn't write anything about them :thumb:

And M1's weight increased over original requirements for new tank weight.

The M1's weight was not increased over the projected weight of the LK 10379 and LK 10382. Also the XM1 prototypes of 1975 (after Chobham was adopted) were still in the weight limits.

Oh and one more thing, Chieftain Mk5/2 have additional special armor over hull sides.

Yes, which weighed as much as 36 mm RHA, while the hull side at crew compartment was made of 50 mm Aluminium. This is weight equivalent to 53 mm RHA... or in other words as heavy as the side armour of the Leopard 1 (45 mm RHA at 40° at the sponsons, 35 mm RHA + 12 mm RHA skirts at the hull side).

The 125mm guns at that time had comparable anti armor eficency as 115mm.

3BM28 115mm APFSDS from 1978 have comparable penetration capability to 3BM22 125mm APFSDS from 1976, which was main APFSDS type used by the Soviet Army even trhough the 1980's.

But the 3BM28 has no impact on the M1 Abrams development. Burlington was adopted in 1974, the weight limit for the XM1 dates back to the TACOM from 1972/1973 and was still valid during the joint American-German evaluation of 1976. The M1 Abrams production started in 1978.
The 3BM-28 was also not very wide spread; you are taking the rarest 115 mm APFSDS and say "that's what the Abrams was designed against"!

Preatty much the basic M1 was well proteced at the front against both 115mm smoothbore and 125mm smoothbore even up to 1985, and after 1985 M1IP and basic M1A1 were still preatty much invurnable to the 125mm APFSDS ammo used by Soviets back then.

Source?

So yeah, talking that M1's armor was good enough only to protect against 115mm APFSDS from 800mm is a nonsense.

Source? And how do you explain the other authors saying that the M1 Abrams was designed for this goal? Are they all dumb?

Yeah, right, as far as I can see, most of so called "speculations" done by me end up as accurate or very close to reality observations.

No.

You obviously never had any closer experience with military requirements and how quickly these can be modified.

I have been working in industry - changing the requirements takes one meeting, but getting the requirements to work properly takes a lot of times. I don't think that cars need much more time than tanks in this regard.

Oh and BTW, actually Hunnicutt mentions that during M1 development, survivability was somehow enhanced by changes to the design. It was during FSED phase of development program, so we can assume that during development, there were constant changes to the vehicle design, and we can actually seen this between early prototypes and both FSED prototypes.

Notice that these changes do not include improved armour or higher armour protection, but crew survivability?

 

[Damian]

He could have stated that the armour was increased to classified levels, just like pretty much all other authors write about armour protection increasements. He didn't wrote anything about thicker or better armour. By your logic, we also could say that the protection requirements could have been decreased, because he doesn't write anything about them

Yes, the possibility is the same.

The M1's weight was not increased over the projected weight of the LK 10379 and LK 10382. Also the XM1 prototypes of 1975 (after Chobham was adopted) were still in the weight limits.

It was increased over some proposed configurations.

Yes, which weighed as much as 36 mm RHA, while the hull side at crew compartment was made of 50 mm Aluminium. This is weight equivalent to 53 mm RHA... or in other words as heavy as the side armour of the Leopard 1 (45 mm RHA at 40° at the sponsons, 35 mm RHA + 12 mm RHA skirts at the hull side).

Add to this the basic hull sides, + suspension, + rest of addon armor, + rest of base armor. It was vehicle with many heavy components.

But the 3BM28 has no impact on the M1 Abrams development. Burlington was adopted in 1974, the weight limit for the XM1 dates back to the TACOM from 1972/1973 and was still valid during the joint American-German evaluation of 1976. The M1 Abrams production started in 1978.
The 3BM-28 was also not very wide spread; you are taking the rarest 115 mm APFSDS and say "that's what the Abrams was designed against"!

First thing is, that we do not know which variant of "Burlington" armor was inducted in to service in the end, development was very rapid and changes were fluid. And M1's production started in 1979 after it was inducted in to service and standarized, this when you start mass production, do not count to this LIRP variants or pre series information series for armed forces, as changes still might occur between them and series versions.

Source?

Look at penetration capabilities of these types of ammunition, conclusion is very obvious.

Source? And how do you explain the other authors saying that the M1 Abrams was designed for this goal? Are they all dumb?

Dumb? No, but they might not have access to all informations.

No.

To the contrary.

I have been working in industry - changing the requirements takes one meeting, but getting the requirements to work properly takes a lot of times. I don't think that cars need much more time than tanks in this regard.

And I am very close to military, and I know how quickly requirements can change simply because new variables appears, or during simple tests something went different than anticipated.

Notice that these changes do not include improved armour or higher armour protection, but crew survivability?

Read again, there is clearly written: Chrysler made a number of additional changes to enhance the survivability of their candidate and to reduce the cost. The arrangement of the special armor was modified and a special armor gun shield replaced the casting on the earlier proposal.

So we can see modification mainly around the armor itself. And the phrase I marked can mean anything, they could changed materials, layers thickness, number of layers and so on. There is many possibilities, especially that the difference between initial proposal for the final turret design and the enhanced variant, differs mostly in the gun mantled area, turret cheeks are similiar between both designs.

 

[methos]

Add to this the basic hull sides, + suspension, + rest of addon armor, + rest of base armor. It was vehicle with many heavy components.

The basic hull sides are already included (50 mm Aluminium). The Chieftain Mk 5/2 was physically much smaller (hull and turret length, height), carried much less fuel and ammunition and . The heavy weight of the armour is the reason for the higher level of protection.

Look at penetration capabilities of these types of ammunition, conclusion is very obvious.

Yes, it is obivous. The M1 Abrams with armour protection against 115 mm APFSDS (maybe 350 mm RHAe vs KE as implied by Zaloga) is not protected against 125 mm APFSDS until 1985 (with penetration above 500 mm RHA at 2,000 m).

Dumb? No, but they might not have access to all informations.

They might also have access to all available informations. You simply assume that they are wrong and that they have access to less sources than Hunnicutt. Do you think this is a logical way to discuss? Zaloga for example who attributes the M1 Abrams with much less protection than you writes in his acknowledgments section about sources from the Army and General Dynamics Land Systems - which is pretty much the same set of sources as used by Hunnicutt.

Read again, there is clearly written: Chrysler made a number of additional changes to enhance the survivability of their candidate and to reduce the cost. The arrangement of the special armor was modified and a special armor gun shield replaced the casting on the earlier proposal.

The arrangement was modified, not the composition. That "arrangement" means "arrangement of the armour layers inside the composite array" is your sole interpretation and not written by Hunnicutt. Hunnicutt wrote arrangement of the special armour - where the armour is located and how thick it is. Chrysler is not the one who designs the armour, they probably didn't even have access to it. Hunnicutt provides a number of drawings on page 192, 193 and 194 about the changes of the Chrysler prototype. The shape of the hull and turret was modified, the earlier prototype had a weaker armoured section in the middle of the turret which was reduced; the turret roof was more exposed on the earlier prototype, just as the lower section of the hull at the driver's station. The armour thickness at the turret front was less uniform and the gap between hull and turret was more exposted.

So we can see modification mainly around the armor itself.

No.

 

[Damian]

The basic hull sides are already included (50 mm Aluminium). The Chieftain Mk 5/2 was physically much smaller (hull and turret length, height), carried much less fuel and ammunition and . The heavy weight of the armour is the reason for the higher level of protection.

I doubt that basic hull was made from alluminium, it have no sense and make vehicle vurnable to fire.

Yes, it is obivous. The M1 Abrams with armour protection against 115 mm APFSDS (maybe 350 mm RHAe vs KE as implied by Zaloga) is not protected against 125 mm APFSDS until 1985 (with penetration above 500 mm RHA at 2,000 m).

Zaloga changed his estimations many times. My conclusion differs from yours, deal with this.

M1 was most likely at the turret front protected on the level of 450-500mm RHAe vs KE, while M1IP and M1A1 was ~600+mm.

They might also have access to all available informations. You simply assume that they are wrong and that they have access to less sources than Hunnicutt. Do you think this is a logical way to discuss? Zaloga for example who attributes the M1 Abrams with much less protection than you writes in his acknowledgments section about sources from the Army and General Dynamics Land Systems - which is pretty much the same set of sources as used by Hunnicutt.

And the same Zaloga changes his mind over time?

Do you trully believe that GDLS and US Army would reveal to Zaloga true protection levels of their tank that are classified?

I doubt even Hunnicutt had access to such data, and he had much better relationship with US Army itself.

I have all Zaloga books about M1, and all of them provide different data about M1's protection, which in itself means we should doubt in his data.

Steven J. Zaloga M1 Abrams Main Battle Tank 1982-1992 published 1993, at page 9-10 he wrotes 350mm RHAe vs KE and 700mm RHAe vs CE for basic variant of the M1.
Steven J. Zaloga M1 Abrams vs T-72 Ural published 2009, at page 15 the same author wrotes 470mm RHAe vs KE and 650mm RHAe vs CE for the same basic variant of the M1.

So not only Zaloga is not credible, but also you are loosing your credibility by not only not knowing this niuanse, but also quoting author who changes his mind over the years.

So or Zaloga is not credible at all, or he get new informations which are more accurate and contradicts your bold statements.

The arrangement was modified, not the composition. That "arrangement" means "arrangement of the armour layers inside the composite array" is your sole interpretation and not written by Hunnicutt. Hunnicutt wrote arrangement of the special armour - where the armour is located and how thick it is. Chrysler is not the one who designs the armour, they probably didn't even have access to it. Hunnicutt provides a number of drawings on page 192, 193 and 194 about the changes of the Chrysler prototype. The shape of the hull and turret was modified, the earlier prototype had a weaker armoured section in the middle of the turret which was reduced; the turret roof was more exposed on the earlier prototype, just as the lower section of the hull at the driver's station. The armour thickness at the turret front was less uniform and the gap between hull and turret was more exposted.

Don't try to tell me what means what. Arrangement can mean anything, did you ever had any closer ties to military and actually knows that military likes to call many things in a very enigmatic thing?

I disagree with you.

No.

Well, then as we say here in Poland, "kit ci w oko".

Let's just agree that we disagree.

 

[Damian]

Interesting, armor modules are looking different, more massive and without these holes like in earlier version on older photo before 2006 Lebanon war, my best guess, some sort of improvement to Merkava Mk4 armor design.

 

[Sovngard]

Interesting, armor modules are looking different, more massive and without these holes like in earlier version on older photo before 2006 Lebanon war, my best guess, some sort of improvement to Merkava Mk4 armor design.

This looks more like a painted metallic frame with bolts whose purpose is to keeping composite armor modules together.

Take a look at the gun mantlet, its armor still has rectangular holes.

BTW, nice video.