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2 minutes ago, Iron Drapes said:

Second hand source, unfortunately: http://below-the-turret-ring.blogspot.my/2017/01/early-m1-abrams-composite-armor.html

"A common design principle according to Dipl.-Ing. Rolf Hilmes, who formerly worked at the German BWB, and according to a presentation from the British Defence Science Technology Laboratory (DSTL), is to incorporate a further heavy layer in front of the armor array, which servers to disrupt (shatter/break) the projectile, before the fragments enter the NERA array."

This jives with the research I posted on high hardness titanium/aluminium plates, as these also work best with a skin of something hard and dense in front to eat up the fast front of a shaped charge jet.

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19 minutes ago, Toxn said:

Welcome!

 

Look at some of my previous posts - I mentioned the application of lateral force.

What greatly puzzles me is how the actual NERA arrays we have pictures of seem to contradict what little coherent theory we have about how they work. If you go over the pictures posted earlier, you find arrays with very small gaps (or no gap), arrays with thicker front plates than back plates and arrays were a lot of the NERA plates are orthogonal to the axis of the penetrator rather than at an oblique angle. I'd love to know why.

 

I agree with you that NERA plates should be further apart (again, see my earlier posts), as the brute physical reality is that the only way to seriously lower the penetration of a long rod or shaped charge jet is to somehow disrupt it or break it up.

 

Yes, and that is the primary (perhaps only) influence of bulging armour.

From what I know, it depends on what sort of material is used in the sandwich layer. The rate of energy transfer differs from material to material, and some reach their peak very quickly. Best guess is that it is simply a matter of optimization. It would be inherently better to have more spacing, as that would be more efficient in terms of mass, but for bulging armour using certain sandwich materials, it may be more efficient thickness wise to stack them more closely. You have a heavier, but slightly more protective array.

As for arrays with thicker front plates than back plates, that is easily explained. "In pursuit" or "forwards" type NERA armour where the bulging plate expands in the same direction of travel as the projectile is more effective than "In retreat" or "backwards" type NERA armour, where the bulging plate expands against the direction of travel of the projectile. These pictures can tell the tale better than I:

 vs+cumulative+jet,+NERA,+backwards.png

vs+cumulative+jet,+NERA.png

 

It would be more beneficial to have a bias in the direction where the NERA plate bulges. In the case of the T-72B, the NERA can only bulge in one direction. The front plate is too thick and too heavy to move at all. More modern designs may be better optimized for certain threats, but I don't really know much in the way of specifics.

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On 16/02/2017 at 1:23 AM, Toxn said:

Looking at the availble DTIC documents, research and patents; it seems that glass/ceramic armours really were the secret sauce for a long while. You can actually test this by looking at penetration in glass, normalising ME and TE to RHA and then multiplying the two. Even though glass has only 60% of the TE of RHA, it has a whopping 6 times ME. Which means that, overall, it is 3.6 times as efficient as RHA.

This is amazing, given that magic titanium alloy has only 1.8 times the efficiency. Even better; glass is cheap and easilty castable. I can't test harder ceramics directly, but my guess is that they'd be better still. And that's just against long rods - ceramics are even more effective against shaped charges.

Just to clarify something, is the 0.6 TE and 6 ME for glass in comparison to RHA for long rods or shaped charges? Those numbers seem feasible for a shaped charge in a laboratory setting with large spacing behind the module, as SM_HH attested to in his post, but the flow of your post seems to imply that those numbers were for long rods.

Considering AMAP-B, one of the most advanced ceramic armour modules available, is designed specifically for defeating KE threats and advertises a ME of 'only' ~4.2, I have a hard time believing that whatever type of glass they used in those tests decades ago would be close to 50% more effective.

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36 minutes ago, DD000 said:

Just to clarify something, is the 0.6 TE and 6 ME for glass in comparison to RHA for long rods or shaped charges? Those numbers seem feasible for a shaped charge in a laboratory setting with large spacing behind the module, as SM_HH attested to in his post, but the flow of your post seems to imply that those numbers were for long rods.

Considering AMAP-B, one of the most advanced ceramic armour modules available, is designed specifically for defeating KE threats and advertises a ME of 'only' ~4.2, I have a hard time believing that whatever type of glass they used in those tests decades ago would be close to 50% more effective.

As I mentioned above, I muffed the ME calculations. The ME is actually more like 2 for something with glass density and a hardness of 500BHN. The threat is a long rod.

 

I can put up the table I generated if you want.

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On 15.02.2017 at 10:38 PM, Collimatrix said:

 

This is why you shouldn't believe wikipedia about the technical aspects of tank design.  Wikipedia articles about tanks are often written by people that have no idea what they're talking about.  Also, I have heard rumors that they are occasionally vandalized by hooligans.  Does it make any sense to you that a tank designed to replace the T-64, T-72 and T-80, all tanks that had composite hull armor, would itself lack composite hull armor?

Moreover, even if the Object 187 prototypes didn't have the composite modules actually installed (no way to be sure), the clearly had provisions for advanced armor on the hull and turret.  Here's a picture of one of them with hull ERA installed:

 

and here is a picture of the turret composite armor package:



Also, what makes the Object 187 glacis design so good isn't the specific armor package that was used in it, it was the shape.  Unlike every other modern tank it lacked the weak point around the driver's position.  But you should know this already, you wrote an article on it once.

I'm beginning to get the impression that you simply enjoy arguing.

 

Actually it did not lacked the weak point around the driver's position, but it was reduced.

It's clear from inside photos. But the level depends on variants.

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23 hours ago, Iron Drapes said:

Second hand source, unfortunately: http://below-the-turret-ring.blogspot.my/2017/01/early-m1-abrams-composite-armor.html

"A common design principle according to Dipl.-Ing. Rolf Hilmes, who formerly worked at the German BWB, and according to a presentation from the British Defence Science Technology Laboratory (DSTL), is to incorporate a further heavy layer in front of the armor array, which servers to disrupt (shatter/break) the projectile, before the fragments enter the NERA array."

This is my blog. I don't know if you got confused by the placement of the photo showing the T-72B's armor array, but the text is not related to the T-72B.

The way Mr. Hilmes describes the development of bulging plates armor (sandwich plate NERA) is essentially that people took conventional multi-layered spaced armor, vulancized rubber at the back and added thin steel plates to it. This might be how the first types of NERA were developed in Germany. According too him, the T-72M1M/T-72B's turret armor, the armor essentially acts like spaced armor against APFSDS ammunition and provides no gain in effective protection, no type of similar looking bulging plates armor is supposed to provide enhanced protection against KE.

The statement from the blog was focused on thicker armor components mounted in front of the general NERA arrays that seem to be part of any modern tank. I mentioned the Leopard 2A5 and the Kontakt-5/Relikt ERA of Soviet/Russian tanks as example. The wedge-shaped armor of the Leopard 2A5 for example consists of two to three (depending on location) rather thick (~70 mm) sandwich plates, which supposedly are made of high-hardness steel. Similar NERA sandwiches have been tested in Germany and the Netherlands against APFSDS and shaped charge warheads with great effect.

MCSVwLk.png

(This is what a NERA sandwich with two 16 mm HHS plates does to a L/D 20 tungsten rod).

The Soviet Kontakt-5 ERA has an areal density of 500 to 550 kg/m², which equals roughly 60 to 70 mm steel per m², or slightly more steel than two of the NERA sandwiches of the T-72B's turret when seeing the armor array directly from the front. The explosive filler leads to a much greater plate bulging/movement than on the T-72B, making it even more effective.

22 hours ago, DD000 said:

Just to clarify something, is the 0.6 TE and 6 ME for glass in comparison to RHA for long rods or shaped charges? Those numbers seem feasible for a shaped charge in a laboratory setting with large spacing behind the module, as SM_HH attested to in his post, but the flow of your post seems to imply that those numbers were for long rods.

Considering AMAP-B, one of the most advanced ceramic armour modules available, is designed specifically for defeating KE threats and advertises a ME of 'only' ~4.2, I have a hard time believing that whatever type of glass they used in those tests decades ago would be close to 50% more effective.

The values were for shaped charges, not for APFSDS rounds. AMAP-B can have a mass efficiency of 5 against kinetic energy projectiles, but only against bullets. The effiency against large calibre penetrators has to be much lower, otherwise a modern day Leopard 1 would be immune to most 120 mm rounds.

16 hours ago, Andrei_bt said:

Actualy to understand this pic

it is not t-80U or UD, it's early 219A

Can you please explain this a bit more? According to R. Lindström, the T-80U send to the Swedish tests had essentially the same armor, just slightly different thickness.

gMpVX66.png

 

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I have seen two documents with Dutch authors on the topic; one is published by two authors from the TNO Prins Maurits Laboratory and Royal Netherlands Army National Supply Agency. I cannot find the second document atm., but I think it was also from the TNO. The ballsitic testing was done with scale APFSDS penetrators in the Netherlands, testing of full scale APFSDS was done in cooperation with W. Odermatt in Thun (Switzerland).

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3 hours ago, SH_MM said:

This is my blog. I don't know if you got confused by the placement of the photo showing the T-72B's armor array, but the text is not related to the T-72B.

The way Mr. Hilmes describes the development of bulging plates armor (sandwich plate NERA) is essentially that people took conventional multi-layered spaced armor, vulancized rubber at the back and added thin steel plates to it. This might be how the first types of NERA were developed in Germany. According too him, the T-72M1M/T-72B's turret armor, the armor essentially acts like spaced armor against APFSDS ammunition and provides no gain in effective protection, no type of similar looking bulging plates armor is supposed to provide enhanced protection against KE.

The statement from the blog was focused on thicker armor components mounted in front of the general NERA arrays that seem to be part of any modern tank. I mentioned the Leopard 2A5 and the Kontakt-5/Relikt ERA of Soviet/Russian tanks as example. The wedge-shaped armor of the Leopard 2A5 for example consists of two to three (depending on location) rather thick (~70 mm) sandwich plates, which supposedly are made of high-hardness steel. Similar NERA sandwiches have been tested in Germany and the Netherlands against APFSDS and shaped charge warheads with great effect.

Do you have a link to the DSTL presentation, please?

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4 hours ago, SH_MM said:

This is my blog. I don't know if you got confused by the placement of the photo showing the T-72B's armor array, but the text is not related to the T-72B.

The way Mr. Hilmes describes the development of bulging plates armor (sandwich plate NERA) is essentially that people took conventional multi-layered spaced armor, vulancized rubber at the back and added thin steel plates to it. This might be how the first types of NERA were developed in Germany. According too him, the T-72M1M/T-72B's turret armor, the armor essentially acts like spaced armor against APFSDS ammunition and provides no gain in effective protection, no type of similar looking bulging plates armor is supposed to provide enhanced protection against KE.

The statement from the blog was focused on thicker armor components mounted in front of the general NERA arrays that seem to be part of any modern tank. I mentioned the Leopard 2A5 and the Kontakt-5/Relikt ERA of Soviet/Russian tanks as example. The wedge-shaped armor of the Leopard 2A5 for example consists of two to three (depending on location) rather thick (~70 mm) sandwich plates, which supposedly are made of high-hardness steel. Similar NERA sandwiches have been tested in Germany and the Netherlands against APFSDS and shaped charge warheads with great effect.

MCSVwLk.png

(This is what a NERA sandwich with two 16 mm HHS plates does to a L/D 20 tungsten rod).

The Soviet Kontakt-5 ERA has an areal density of 500 to 550 kg/m², which equals roughly 60 to 70 mm steel per m², or slightly more steel than two of the NERA sandwiches of the T-72B's turret when seeing the armor array directly from the front. The explosive filler leads to a much greater plate bulging/movement than on the T-72B, making it even more effective.

I see. This is very clear now, thank you. 

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---Can you please explain this a bit more? According to R. Lindström, the T-80U send to the Swedish tests had essentially the same armor, just slightly different thickness.

Hi! I can not explain what did they send to Sweeden, just it's not wat was in T-80U-UD. it's early 219A like on a drawing well known for years.

But the above mentioned Swedish picture describes the overall design rather good. Cast plates with holes in them (both sides) filled with resin.

 

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17 hours ago, SH_MM said:

Can you please explain this a bit more? According to R. Lindström, the T-80U send to the Swedish tests had essentially the same armor, just slightly different thickness.

gMpVX66.png

 

 

From South Korea Pz-3IT600 testes:

first four layouts represent T-80U hull and turret lauout. It's shematic, but rather good represent.

muth8Y3.jpg

And this is T-80U hull layout (it was relase on otvaga so I can put here it:) ) - values in red and colors are made by myself. This is factory hull layout for late T-80U or erly UD - relase on otvaga as I remember. 

As You can see - the same as in South Korea pdf form PzF-3IT600

UCVojM7.jpg'

 

 

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My working table for longrod armour:

 

Material Density (g/cm^3) Hardness (BHN) Penetration depth (cm) Mass Efficiency (scaled to RHA) RHA-scaled TE TE*ME
orthoclase 2.6 450.0 93.0 1.9 0.6 1.2
staballoy 19.1 450.0 34.2 0.7 1.7 1.2
high-hardness steel 7.9 500.0 53.4 1.1 1.1 1.2
quartz 2.2 500.0 101.0 2.0 0.6 1.2
fuzed silica array (50mm slabs of fuzed silica encased in plastic and sandwiched between 10mm RHA) 3.5   82.0 1.6 0.7 1.1
apatite 3.2 325.0 88.3 1.6 0.7 1.0
RHA 7.9 300.0 57.4 1.0 1.0 1.0
high-hardness titanium 4.4 300.0 76.7 1.3 0.7 1.0
Burlington array 1.6   199.0 1.4 0.7 1.0
Turning array (20mm plate + 20mm gap; 60' from vertical) 3.9   91.8 1.3 0.6 0.8
phosphor bronze 8.9 200.0 61.7 0.8 0.9 0.8
brass 8.5 180.0 65.4 0.8 0.9 0.7
mild steel 7.9 150.0 72.0 0.8 0.8 0.6
flourite 3.0 150.0 116.6 1.3 0.5 0.6
high-hardness Aluminium 2.8 150.0 120.7 1.3 0.5 0.6
standard reinforced concrete 2.4   220.0 0.9 0.3 0.2

 

Hardness values indicate where materials have been run through long-rods (which can only calculate penetration against targets between 150 and 500 BHN). Other values represent averaged results (eg: fuzed silica array), calculated results using other research documents (eg: turning array) or observed results (eg: the concrete results, which were estimated by using penetration values for 30x173mm APFSDS).

 

ME is calculated like so: (density X*penetration X)/(density Y*penetration Y); where X is RHA, density is in g/cm^3 and penetration is in cm.

ME*TE is what it says on the tin: an unweighted multiplication of the RHA-scaled ME and TE values.

As you can see, homogenous quartz would be good for armour if you could make slabs of it big enough to fil out a given cavity and then keep it from cracking somehow. Presumably magic ceramics (which longrods can't calculate) would be even better by dint of having ridiculous hardness values.

High-hardness steel is another good option, for the simple reason that it is a bit more thickness efficient then steel while having the same mass efficiency. It probably also costs very little compared to sheets of ceramic or staballoy. This makes triple hardness plates seem pretty legit as armour components. 

The turning array assumes that the penetrator will turn very little as it hits each plate (less than 1'). This means that the overall penetration loss should be something like 20% over a similar weight of homogenous steel. I'd love to have more accurate values here.

The burlington penetration depth was calculated from the ME values given earlier in the thread. The density was calculated by looking at other NERA arrays using oblique plates with wide gaps. More data would be good here too.

 

Again: biological armour (a giant tooth or enamel scale, essentially) would actually be surprisingly effective. Biotank designs intensify.

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9 hours ago, Militarysta said:

4qWnBQF.jpg

 

Fa32YcD.jpg

This is interesting. Also very useful. What's the source for this exactly?

One thing that jumps out to me is that the values for the mass efficiency against APFSDS is similar to the values you'd expect against small arms bullets, which lends credence to the theory that the nano-ceramics used in the AMAP modules would be about as efficient against long rods as they would against AP bullets. 

What does it say for the 6th material down? The one with a density of 1.0 - 1.1 g/cc. (Also, it triggers me that the rows for the material and values in the second table aren't aligned...)

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8 hours ago, DD000 said:

What does it say for the 6th material down? The one with a density of 1.0 - 1.1 g/cc. (Also, it triggers me that the rows for the material and values in the second table aren't aligned...)

It's polyurethane. No idea what the extra text says.

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Considering the simplicity of NERA arrays, could a country, like say Norway or Denmark,  produce composite armor? 

As long as we could make HHS, the rest should be simple, right? 

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3 minutes ago, Collimatrix said:

Isn't Israel making the armor arrays for the Merkava IV on their own?  Israel is pretty small.

Israel has a far better developed defense industry, so it is a bad comparison. But I do see your point. 

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