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On 9/18/2016 at 11:22 AM, Militarysta said:

 

lzzHrc2.png

 

 

On 9/18/2016 at 10:18 AM, Militarysta said:

 

D5jsKZ3.jpg

 

Did the 740mm penetration figure for CHARM 3 originate from a publication(?) called JCollins?

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18 hours ago, Ramlaen said:

Did the 740mm penetration figure for CHARM 3 originate from a publication(?) called JCollins?

 

JCollins aka Jake Collins is a member of several wargaming communities, he is not a publication. He used to post on the Tank-Net, but stopped some years ago. He had a reference guide for wargaming on his websites with estimated/guessed protection and penetration values, all of them really, really questionable (for example he falsely believed that Leopard 1A1A1 and Leopard 1A5 have different armor types and Leopard 1A5 turret had some 400-500 mm RHA vs KE...). Once his website was quoted on Tank-Net, where he mentioned that it is not meant for anything besides wargaming and does not reflect reality.

 

That said some of the penetration values in the table might be based on his website...

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How would low L/D help?  US penetrator designs have a breakaway tip, which naturally forces the L/D higher.  European designs have the concealed needle tip (and it looks like this one may too), which also forces L/D higher.

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The tip is not useful against composite armor as it's designed as an anti-ERA measure. It'll just go off very quickly.

Extensive NxRA/NERA arrays will attempt to bend and break the rod over and over again as it passes through more reactive layers, not as a single depleting armor plate.

 

Hence, a thinner rod, or in other words; one with higher L/D ratio, will be more susceptible to bending and subsequently breaking.

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The needle tip on the German APFSDS designs, as I understand it, is for making a small hole in heavy ERA like K5 without detonating the explosive.  The rest of the penetrator can then follow through this small hole undisturbed.  This approach works because the explosives in ERA have to be fairly insensitive for safety reasons and so the ERA protection can't get stripped off the tank with small arms fire or a single artillery airburst.

 

Since NERA gets its energy from the penetrator, this approach seems like it would work against NERA as well.  The needle tip would poke a hole in the initial layers of NERA, but because it is narrower, it isn't providing as much energy to the elastomer layer, and therefore vaporizes less of it.  Since there is less vaporization, less metal is fed into the path of the penetrator.

 

I'm not sure that high L/D penetrators are longer because they are thinner than low L/D ones.  Rather, I think they get their high L/D by being just as (or almost as) thick, and being a bit slower.  At APFSDS velocities the gun is really inefficient, because it's starting to get close to the velocity ceiling of the propellant.  So you can actually add quite a bit of projectile mass for relatively little loss in velocity.

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I don't see how that works. The big penetrator rod will not be able to fit into the small hole made by the needle tip, so the rod will inevitably detonate the ERA or activate the NERA when it impacts. Rather, I think that the needle tip is supposed to be made of some softer metal, and it mushrooms out upon impact to create a relatively large hole in the front plate of ERA like Kontakt-5. The mushrooming effect will create this hole gradually as opposed to simply pricking a hole, thus decreasing the impulse transferred to the explosive charge underneath, while simultaneously creating a hole large enough for the rod to fit through. In this version of events, I imagine that the rod will penetrate the explosive layer and be halfway through before it detonates, and when it detonates, the flyer plate will maybe only catch the fins at the tail of the rod.

 

Also, feeding metal into the penetrator is probably not how ERA and NERA work. The flyer plate will definitely get a big oval hole gouged into it, but what actually happens is the flyer plate impacts the penetrator laterally, and the penetrator gets bent by the impact and becomes yawed. For shaped charges, the flyer plate works by hitting the middle and tail section of the cumulative jet, thus disrupting its shape. If feeding metal is the mechanism at play, then why is a backwards-flying flyer plate less effective than a forwards-flying flyer plate when both are the same mass, same thickness, same material, same obliquity and travelling at the same speed except in different directions?

 

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

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1 hour ago, Iron Drapes said:

I don't see how that works. The big penetrator rod will not be able to fit into the small hole made by the needle tip, so the rod will inevitably detonate the ERA or activate the NERA when it impacts. Rather, I think that the needle tip is supposed to be made of some softer metal, and it mushrooms out upon impact to create a relatively large hole in the front plate of ERA like Kontakt-5. The mushrooming effect will create this hole gradually as opposed to simply pricking a hole, thus decreasing the impulse transferred to the explosive charge underneath, while simultaneously creating a hole large enough for the rod to fit through. In this version of events, I imagine that the rod will penetrate the explosive layer and be halfway through before it detonates, and when it detonates, the flyer plate will maybe only catch the fins at the tail of the rod.

The explosive compound in ERA (well, any military explosive compound) will only detonate when a certain pressure is reached. If the impact does not reach that pressure, the explosive will not detonate. As long as the pressure doesn't go above a certain threshold it doesn't matter what's hitting the explosive, it simply won't explode. I suppose there's a way to poke a hole through ERA without setting it off, but I haven't yet figured out how exactly.

 

1 hour ago, Iron Drapes said:

Also, feeding metal into the penetrator is probably not how ERA and NERA work. The flyer plate will definitely get a big oval hole gouged into it, but what actually happens is the flyer plate impacts the penetrator laterally, and the penetrator gets bent by the impact and becomes yawed. For shaped charges, the flyer plate works by hitting the middle and tail section of the cumulative jet, thus disrupting its shape. If feeding metal is the mechanism at play, then why is a backwards-flying flyer plate less effective than a forwards-flying flyer plate when both are the same mass, same thickness, same material, same obliquity and travelling at the same speed except in different directions?

 

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

It is. 

 

If you look at various tests with actual ERA, you'll see that the jet isn't noticeably being yawed/deflected, no matter the ERA angle:

3fc5bd8abf.jpg

You can however see that the higher the angle of the ERA compared to the jet, the more disturbed the jet is. This is simply because the ERA is capable of feeding more material into the jet, degrading it.

 

Actually, here are a bunch of photos of a shaped charge jets versus NERA at different angles:

6bd274f4eb.jpg

 

And again, the more material is fed into the jet, the worse it becomes. 

 

 

However, ERA and NERA do actually deflect the jet, but only very slightly. I'm talking about ~50 m/s down for a 55 degree angle ERA sandwich. 50 m/s might sound a lot, until you realise that these jets move forward at a few thousand meters per second. So the downward velocity is negligible.

fbea76a062.jpg

 

 

The reason the forwards moving flyer plate caused more damage to the jet is because of... vectors, basically..

 

Or as Kobylkin and Dorokhov put it:

Quote

 

1. Based on the analysis of SCJ interaction with moving reactive armor plates, the lateral impulse transferred to the SCJ by the plates moving at an angle was estimated. The main feature of the interaction of the SCJ with the reactive armor plates is that for the same time interval, the SCJ element interacting with the front plate is of greater length than that interacting with the rear plate.

2. Since the transverse velocity imparted to the SCJ during interaction with the front plate is lower than the plate velocity component perpendicular to the SCJ, the interaction of the main part of the SCJ with the front plate has a continuous nature and leads to wearing of SCJ in the transverse direction (reduction in the SCJ diameter) and a small deflection by an angle α.

3. In the interaction of the SCJ with the rear plate, the transverse velocity acquired by the SCJ exceeds the plate velocity component perpendicular to the SCJ, so that the SCJ periodically bounces off the plate and the interaction of the SCJ with the rear plate has a nonstationary discrete nature and forms transverse perturbations in the SCJ , which, developing, lead to its distortion and subsequent destruction.

4. The transverse perturbations arising in the SCJ can be considered as shear waves in a string in a plastic state. Due to the low velocity of their propagation (≈ 100 m/s), these waves are localized, and their development leads to rapid destruction of the deformed parts of the SCJ.

 

 

Also, this is what the paper says about the pictures you linked:

5228f84ba3.png

 

Here are the pictures in higher res by the way, for future use:

ea62e4fa16.jpg

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I'm afraid that there must either be some misunderstanding or you are attributing effects to the wrong causes. By saying that NERA works by feeding metal into the path of the jet, Collimatrix is saying that it is not proactively reducing the penetration of the jet by disturbing it, but only making it "use up" its penetration potential into a thin metal plate by making the thin metal plate move at some angle to the jet to somehow increase its LOS thickness, which is plain wrong. I am saying that the movement of the thin plate disrupts the shape of the jet, making it collapse. This is what Kobylkin and Dorokhov meant - that the lateral movement of a plate across the path of a cumulative jet causes disturbances. I don't know which specific statement you are pointing to, so let me break them all down:

 

Statement 1 says nothing about feeding more material into the jet, only saying that the front plate of the ERA interacts with a longer segment of the cumulative jet than the rear plate.

 

Statement 2 says that for the front plate, the transverse velocity induced into the jet is lesser than the lateral velocity induced into the jet. In statement 3, he says the opposite - that for the rear plate, the transverse velocity induced into the jet is greater than the lateral velocity. He then goes on to report that the transverse perturbations in the jet, leading to its destruction, and further clarifies this in statement 4. These statements explain why you see parts of the jet broken off and going up and down, while some other parts are perfectly fine and still fly straight. As it is said in statement 4: the waves of transverse perturbations are localized. Localized means that some parts of the jet are affected and some are not. This totally supports my claim that ERA and NERA work by disrupting the shape of the jet, not by feeding metal into it. I never said that ERA and NERA work by changing the direction of the jet or by causing it to yaw.

 

 

I don't know what you mean by quoting the paragraph about the backwards/forward plates. The paragraph is not saying that the disturbances caused in the tip of the jet attacked by the forward moving plate (b) was due to the explosion that propelled the plate. It is saying that about the backwards moving plate (a). Can you clarify?

 

Actually, it would be even better if you could clarify what is meant by "metal is fed into the path of the penetrator" in the first place. Are you saying that the amount of metal that the jet has to go through when it penetrates a ERA or NERA module is increased by the movement of the plate? Are you saying that a 3mm steel plate from a NERA can have 100mm of LOS armour value because it moves in some direction to the jet?

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4 minutes ago, Iron Drapes said:

I'm afraid that there must either be some misunderstanding or you are attributing effects to the wrong causes. By saying that ERA and NERA works by feeding more material into the jet, you are saying that it is not really reducing the penetration of the jet, but only making it "use up" its penetration potential into a thin plate by making the thin plate move at some angle to the jet. I am saying that the movement of the thin plate disrupts the shape of the jet, making it collapse. This is what Kobylkin and Dorokhov meant - that the lateral movement of a plate across the path of a cumulative jet causes disturbances. I don't know which specific statement you are pointing to, so let me break them all down:

 

Statement 1 says nothing about feeding more material into the jet, only saying that the front plate of the ERA interacts with a longer segment of the cumulative jet than the rear plate.

 

Statement 2 says that for the front plate, the transverse velocity induced into the jet is lesser than the lateral velocity induced into the jet. In statement 3, he says the opposite - that for the rear plate, the transverse velocity induced into the jet is greater than the lateral velocity. He then goes on to report that the transverse perturbations in the jet, leading to its destruction, and further clarifies this in statement 4. These statements explain why you see parts of the jet broken off and going up and down, while some other parts are perfectly fine and still fly straight. As it is said in statement 4: the waves of transverse perturbations are localized. Localized means that some parts of the jet are affected and some are not. This totally supports my claim that ERA and NERA work by disrupting the shape of the jet, not by feeding more material into it. I never said that ERA and NERA work by changing the direction of the jet or by causing it to yaw.

 

 

I don't know what you mean by quoting the paragraph about the backwards/forward plates. The paragraph is not saying that the disturbances caused in the tip of the jet attacked by the forward moving plate (b) was due to the explosion that propelled the plate. It is saying that about the backwards moving plate (a). Can you clarify?

 

Actually, it would be even better if you could clarify what you mean by "feeding material into the SCJ" in the first place. Are you saying that the amount of metal that the jet has to go through when it penetrates a ERA or NERA module is increased by the movement of the plate? Are you saying that a 3mm steel plate from a NERA can have 100mm of LOS armour value because it moves in some direction to the jet?

The bit I quoted from Kobylkin was directed at your question about why the FMP has a different effect than the BMP, not at whether or not feeding material into the jet lowers penetration.

 

Anyway, yes, the main reason why ERA/NERA works is due to feeding material into the jet. Since a penetrator can only penetrate a finite amount of armour, you can lower the thickness of main armour it can penetrate by feeding material (armour) into its path.

 

The faster a plate moves, the more material it can feed into the jet before the jet has passed the plate. A plate basically looks like this after the jet has gone through it:

3c2267c589.jpg

And the faster the plate goes, the longer Lslit will be. To be specific, it can be calculated with this formula:7da476705d.jpg

 

The jet will also pass through more material if the angle of the ERA/NERA is increased:

ace9cd1ae5.jpg

 

And what happens when you increase the thickness of the FMP and BMP?

9d4d4290a3.jpg

795f2602ea.jpg

(Note that the BMP in the FMP test is 8 mm thick while the FMP in the BMP test is 1 mm)

 

Anyway, there's lots more I want to say, but I'm a bit ill at the moment so staring at journals and papers isn't the smartest thing to do, I'm already getting a headache and yet I only have a few journals open:

83f1c1926e.png

 

I'll get back to this when I'm feeling better, I'm sorry for not being able to give a concise answer at the moment. Or maybe @Collimatrix can take over, he knows about as much as I do on this subject.

 

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"The bit I quoted from Kobylkin was directed at your question about why the FMP has a different effect than the BMP, not at whether or not feeding material into the jet lowers penetration."

 

How are you not aware that what Kobylkin wrote completely contradicts your theory? He not only states the differences between the front flyer plate and rear flyer plate, he also specifies their method of operation quite clearly. He very clearly said that:

 

"transverse perturbations in the SCJ , which, developing, lead to its distortion and subsequent destruction"

 

Notice the keywords "distortion" and "destruction". He is saying very clearly - and I must repeat, VERY clearly that the moving plate distorts and destroys parts of the jet as it passes through the plate. He doesn't say that the jet is "depleted" or "spent" or "bleeds energy" into the plate. He says that the jet is destroyed by the plate. Please, please, please read carefully!!!!

 

When you recover from your headache, take another look at all of those papers and realize that all of them explain that the effect of moving plates on cumulative jets is disruption and destruction. This statement: "Since a penetrator can only penetrate a finite amount of armour, you can lower the thickness of main armour it can penetrate by feeding material (armour) into its path" is simply unsupported by any research, because what you are saying implies that the jet itself is unharmed. That the jet flies as straight and true as ever before, only that it is penetrating into something else instead of the main armour. That is not what we see in any of the research done on this topic. In every experiment, what we see is the movement of the flyer plate/bulging plate basically breaking off the jet in the middle so that only small segments slip through intermittently. Take a look at this again: 

 

 

ea62e4fa16.jpg

 

 

How does a backward moving plate feed less armour into the jet than a forward moving plate? Both are angled at the same obliquity, both plates are the same thickness, both are propelled at the same velocity, and both are angled in the same plane, only the direction of attack is not the same. 'x' plate thickness ÷ cos θ° will equal the same LOS thickness for both plates, no matter which direction they go. In fact, go and look at the graphs of penetration vs thickness you posted, and you will not be able to reconcile your wild fantasy theory. You cannot turn a flyer plate of 100x50x3 (LxWxH) dimensions into 200mm of armour by moving it at an angle to a plate, no matter how hard you try.

 

If you actually measure Lslit, you can see that it is much, much too little armour to account for the huge decrease in armour penetration after the jet passes through the ERA. We can conclude very easily and painlessly that the primary factor here has nothing to do with feeding armour into the jet at all. A cursory Google search reveals this very quickly: http://appliedmechanics.asmedigitalcollection.asme.org/article.aspx?articleid=1421015 

 

"The main features of the defeat mechanisms of the armor are therefore well known. The origin of the irregular disturbances on the shaped charge jet, which leads to the severe fragmentation and scattering of the jet, is however not described in literature. As this scattering of the jet provides the main protection mechanism of the armor, it is of interest to understand the details of the interaction and the origin of the disturbances. Some experimental observations have been made showing that the backward moving plate often displaces the jet relatively smoothly while it is the interaction with the forward moving plate that causes the disturbances that leads to fragmentation and scattering of the jet. In this work, a mechanism for the interaction is proposed based on the theory of Kelvin–Helmholtz instabilities, which explains the origin of the disturbances on the jet due to the interaction with the forward moving plate. "

 

Please read carefully. The most important part is: "irregular disturbances on the shaped charge jet, which leads to the severe fragmentation and scattering of the jet". It is amply clear that the protective mechanism comes from attacking and destroying the cumulative jet, not by pacifying it by feeding it metal. I suggest that you actually stop to read the text in those journals and papers you have open instead of posting raw data that proves nothing for anyone, neither you or me. If you read the analysis done by the researchers instead of coming up with wild theories of your own, you will see that they say that the method of operation of flyer plates and bulging plates is exactly how I have been repeating.

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21 hours ago, Iron Drapes said:

"The bit I quoted from Kobylkin was directed at your question about why the FMP has a different effect than the BMP, not at whether or not feeding material into the jet lowers penetration."

 

How are you not aware that what Kobylkin wrote completely contradicts your theory? He not only states the differences between the front flyer plate and rear flyer plate, he also specifies their method of operation quite clearly. He very clearly said that:

 

"transverse perturbations in the SCJ , which, developing, lead to its distortion and subsequent destruction"

 

Notice the keywords "distortion" and "destruction". He is saying very clearly - and I must repeat, VERY clearly that the moving plate distorts and destroys parts of the jet as it passes through the plate. He doesn't say that the jet is "depleted" or "spent" or "bleeds energy" into the plate. He says that the jet is destroyed by the plate. Please, please, please read carefully!!!!

I never even took the words "depleted", "spent" or "bleed energy" in my mouth. Maybe you should read carefully?

 

Kobylkin also says this (in the same paper):

Quote

The detonation products accelerate the plates, which impacts at an angle the SCJ. This leads to deflection, destruction or wearing of the SCJ, resulting in a significant reduction in the depth of penetration of the main part of the target located behind the reactive armor.

 

Mickovic:

Quote

When a shaped charge jet hits the cassette, the explosive is detonated and the plates are pushed to the side. The movement of the plates causes the impact point of the jet to constantly shift to new untouched regions, increasing the dynamic effective thickness of the plates

 

Hazell:

Quote

Because the jet is moving at a velocity within the range of 6–10mm/ms (the jet will be stretching with the tip moving more rapidly than the slug), it is necessary to accelerate the plates to a very high velocity to maximize the amount of material offered to the jet.

 

Hazell, again in a different publication:

Quote

Therefore, the outer steel plate moves across the path of the jet thereby continually offering fresh steel to perforate – cutting a slot in the moving plate or plates.

 

Kobylkin, again:

Quote

Motion of the plate at an angle to the SCJ head-on or co-directionally to the SCJ leads to impact contact of the edge of the hole in the plate with the side face of the next elements of the SCJ. This leads to partial (or entire) wearing of the SCJ element

 

Held:

Quote

The tip of the jet creates an elliptical hole in the target or in the sandwich plates and the edge of the hole needs some time before the bulging plates are touching the passing jet the first time and are creating the first deviation. By the interaction of the bulging plate with the jet, the plate is now a little more eroded or more consumed and the plate has to move again some distance that the edge of the slit in the plate interferes a second time with the passing jet. This process is iteratively continuing and gives the multiple eruptions along the jet.

 

 

21 hours ago, Iron Drapes said:

This statement: "Since a penetrator can only penetrate a finite amount of armour, you can lower the thickness of main armour it can penetrate by feeding material (armour) into its path" is simply unsupported by any research

Eehhh... hello? Eroding a penetrator is a basic hydrodynamic interaction principle? Unsupported by any research? Fuck me sideways, hydrodynamic interaction between a penetrator and armour is where any decent researcher will start. If someone doesn't understand hydrodynamic interactions it's nearly impossible to understand the penetration mechanics behind APFSDS and HEAT.

 

The penetration formula for a HEAT jet is basically the same fucking formula as the one used for hydrodynamic penetration:

107ff55343.png

^ HEAT jet penetration formula

 

1eeeda3da8.png

^ Hydrodynamic penetration formula

 

Both formulas are from Hazell's excellent book called "Armour; Materials, Design, and Theory".

 

21 hours ago, Iron Drapes said:

How does a backward moving plate feed less armour into the jet than a forward moving plate? Both are angled at the same obliquity, both plates are the same thickness, both are propelled at the same velocity, and both are angled in the same plane, only the direction of attack is not the same.

Hello again, are you even reading what you type? You're literally giving the answer to your own question: vectors

 

Do you understand how those work?

 

21 hours ago, Iron Drapes said:

 'x' plate thickness ÷ cos θ° will equal the same LOS thickness for both plates, no matter which direction they go

Evidently not.

 

Hey here's a hint: THE JET IS MOVING TOO

 

LIKE

 

REALLY REALLY FAST

 

21 hours ago, Iron Drapes said:

If you actually measure Lslit, you can see that it is much, much too little armour to account for the huge decrease in armour penetration after the jet passes through the ERA. We can conclude very easily and painlessly that the primary factor here has nothing to do with feeding armour into the jet at all. A cursory Google search reveals this very quickly: http://appliedmechanics.asmedigitalcollection.asme.org/article.aspx?articleid=1421015 

Maybe you shouldn't base your rambling on a single source you apparently do not even have access to which is also fully focussed on figuring out a single aspect of HEAT vs ERA interaction. Shit, if you actually properly read the conclusion of the paper you linked you'd have noticed that it starts with "It is proposed that [...]". For some reason you read that as "IT ABSOLUTELY AND TOTALLY IS THIS".

 

Since we're apparently going to sling journals and papers around, here's a thing for you to read (well, multiple things actually): Everything a fellow called Manfred Held has ever written on ERA, since he was one of the people who invented the fucking thing.

 

But anyway, you just stay you and keep claiming that ERA works by magically interfering with the jet. You correctly said that an impact will create a larger crater than the diameter of the penetrator. Which means that if the plates aren't moving into the path of the jet, ERA/NERA will have no effect. As can be seen in the picture I've posted before:

1de3aa1eb4.jpg

See? No effect on the penetrator what-so-ever. 

 

But guess what, if you angle the ERA/NERA so that the plates will actually intersect the jet, things happen!

f16fa6c692.jpg

 

So no, ERA/NERA does not fucking work if you don't feed material into the jet.

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Dude... Of course ERA/NERA does not work if you don't feed material into the jet. Where have I said that ERA/NERA can work even if the flyer plate/bulging plate does not touch the penetrator? What point are you trying to make? You think I don't understand that when a cumulative jet perforates a plate moving laterally across it, it creates a slit into the plate? You are trying so hard to prove me wrong that you don't really read what I am saying. Yes, moving material into the path of the jet at a lateral angle is what causes the reduction in the penetration of the jet, and what I am saying is that moving material into the path of the jet has the effect of disturbing and destabilizing the jet, to the point of destruction. What are you trying to dispute? Every single quote you gave supports this. Yes, moving the plate increases the dynamic thickness, because the jet is presented with a new facet of the plate as it moves against it, but if you read further, you will see that this is not the point that the authors were trying to make. It is simply an observed phenomenon. It is not the REASON why ERA/NERA is effective at reducing the penetration of the jet. It is a BYPRODUCT of it. The REASON why ERA/NERA is effective at reducing the penetration of the jet is because, as you quoted:

 

The detonation products accelerate the plates, which impacts at an angle the SCJ. This leads to deflection, destruction or wearing of the SCJ, resulting in a significant reduction in the depth of penetration of the main part of the target located behind the reactive armor.

 

This is the only thing that I have been trying to say all this while. That the impact of the moving plate with the cumulative jet reduces the penetration of the cumulative jet by interfering with its structure, so that it is no longer a stable projectile and is destroyed in flight. Why do you keep thinking that I am disputing the fact that the movement of the flyer plate/bulging plate increases the amount of plate material that interacts with the jet? I am saying, and I repeat, that the reason for the reduction in penetration of the jet is not because it spends its penetration potential by penetrating into the plate, but because the plate attacks and destroys the jet. What you are saying is something like "a lot of heat is generated at the point of impact, therefore we can conclude that the shaped charge penetrates the target by melting its way through". Do you get me? Cutting a slit into the moving plate is merely a BYPRODUCT of the interaction, the intention and underlying mechanism of which is to destroy the jet. The moving plate/bulging plate destroys the jet by moving against it at an angle.

 

Here's an analogy for you:

 

A rod of something is flying at a 1000mm block of steel at tremendous speed, and it penetrates 600mm into it. ERA and NERA works by chipping off parts of the rod, blunting the tip, creating a fracture down the middle and giving it a yaw of 5 degrees. When the rod hits the block of steel, most of it shatters and a little bit of it penetrates 100mm.

 

You are saying that ERA/NERA works by adding 500mm of steel in front of the block, so that the rod has to penetrate 500mm of extra steel before it hits the block, so the effect is that it can only penetrate 100mm into the block. This is asinine, of course, and I simply cannot believe that you believe this... do you? I am completely flabbergasted that you think that I am thinking that ERA/NERA works without the jet touching the flyer plate/bulging plate.

 

Here's another analogy:

 

Me:

 

Step 1: Move plate at an angle in such a way that it intersects with the jet.

Step 2: Interaction between plate and jet causes destruction of the jet.

Step 3: Jet loses penetration potential.

 

You:

 

Step 1: Move plate at an angle in such a way that it intersects with the jet.

Step 1: Jet loses penetration potential.

 

By the way, I actually do have that document, but I can't copy and paste from it because it is a scan, so I used a free excerpt that I found as I scoured for a pdf version.

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Okay you've got me.

 

Time to stop this discussion.

 

You totally and absolutely got me.

 

I have no words for this.

 

Mainly because I simply cannot understand the level of your knowledge because it's simply too low. Congratulations, you're one of the very few people that are so retarded I physically cannot have a discussion with you.

 

You manage to mix truths, lies and bullshit to get to an even higher level of bullshit that's not even related to the subject in the first place.

 

The only thing I'm going to reply to is this:

19 hours ago, Iron Drapes said:

You are saying that ERA/NERA works by adding 500mm of steel in front of the block, so that the rod has to penetrate 500mm of extra steel before it hits the block, so the effect is that it can only penetrate 100mm into the block. This is asinine, of course, and I simply cannot believe that you believe this... do you?

Yes, that is exactly how the effectiveness of ERA is measured:

9ecc562c16.jpg

 

So get fucked, and take the fucking bus off of this forum and don't like the fucking windows please. You can come back after you understand the basics of armour penetration. Which will be never.

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It's almost funny to see you pretending to be of the same caliber as the researchers that you cite, because clearly, you only pick out what you want to read and discard the rest, and it's also funny how you berate me for citing papers that I apparently do not have, because you are just referring to free open source papers like everyone else. I know this because I am reading the same paper that you are reading: "A Model for Explosive Reactive Armor Interaction with

Shaped Charge Jet": http://onlinelibrary.wiley.com/doi/10.1002/prep.201500163/epdf At least have the courtesy to share what you are reading instead of trying to be all high and mighty about how great and smart you are.

 

Yes, I see where you took that equation from (p. 60), and you are assuming that I know nothing about it. You are trying to fool me and everyone reading by bullshitting me and outright lying to everyone. That equation has nothing to do with finding out penetration of SCJ after interaction with ERA, and you are trying to conceal that fact by omitting information. Read the sentence below that equation:

 

7tq2H0B.png

 

In other words, the equation is designed to find out the difference in results when the distance from the target, Z0, is compared to Z0' in the NERA code, NERA code being a computer code for simulating ERA. A single glance at the equation already tells you that it will give you a ratio, not a figure of armour penetration. That's because this paper is dealing with verifying NERA computer code with experimental results, not to find out why ERA works the way it does.

 

And no, ERA still doesn't work the way you think it works just because you are throwing a temper tantrum. For example, this is something Held stated:

 

One effective protection method used at present is disturbance of the SCJ stabilities by additional armour to reduce the SCJ's penetration ability prior to attacking the main armour. Explosive reactive armours are widely used in tanks because of their excellent interference ability

 

The keywords are "disturbance of the SCJ stabilities" and "interference ability". Yes, feeding material into the jet is how the disturbance and interference is achieved. How else do you get the jet and the plate to interact? However, that is simply not the reason why ERA works, and it is one of the main reasons why ERA cannot be modeled as a fixed figure of extra steel armour on top of the base armour, which is what you are suggesting. You are deliberately ignoring what happens to the jet itself when it passes through the ERA: the stable flow of the jet material (copper) from the tail to the tip (accelerating along the way) is cut by the moving plates of the ERA. The cutting action produces shockwaves in the jet, causing it to disintegrate. The tip, which moves at hypervelocity, usually escapes the interaction with the moving plate and will continue to penetrate some small amount of armour.

 

Maybe you are having some sort of crisis because you have been believing that ERA works like some magical extra armour your whole life. But please, don't post blatant lies. It makes you look bad.

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BTW, Manfred Held has actually done research that deals exactly with the phenomenon that you describe in a paper called  "Dynamic Plate Thickness of ERA Sandwiches against Shaped Charge Jets": http://onlinelibrary.wiley.com/doi/10.1002/prep.200400051/epdf Held acknowledges that the relative thickness of the moving plate as it moves laterally across the SCJ is a factor in the reduction in penetration, but it is a minor factor compared to the disruption and interference of the jet itself. This is what he says: 

 

The equation for the dynamic plate thickness is derived as a function of standoff distance Z0, jet tip velocity vj0, cutoff velocity vjc, plate velocities vPI and NATO angle of the ERA sandwich. The dynamic thickness is presented as functions of the different parameters for the front plate – flying against the shaped charge jet – and the rear plate – flying with the shaped charge jet. But the dynamic thickness is only one of the reduction factors of ERA sandwiches.

 

In the introduction he says this;

 

The remarkable reduction of the shaped charge jet penetration can be explained by three different phenomenological effects [5]:

  • increased dynamic plate thickness
  • jet deflection by the interference of the flying plates wit hthe passing shaped charge jet [6]
  • introduced detonative shock waves into the stretching jetand the interaction of the reaction products with passingjet sections [7]

 

These are all his words verbatim:

 

"As mentioned in the introduction, the reason for the disturbances of shaped charge jets and KE rounds by ERA sandwiches are split, into the dynamic thickness, described in detail here, the jet deflection and the interaction with the reaction products of the detonating high explosive charge.Besides smaller interacting effects, like not at all or less disturbed jet tip regions [12], the main effect comes from vaporising and sputtering of the passing shaped charge jet, as it touches iteratively the edge of the flying plates. This is summarised under the term deflection effect. Partially the jet and especially KE rounds are also lifted up by the transferred momentum [13]. This explains the experimental findings that thicker slower flying plates with less achieved dynamic thickness have at least the same or more effect against shaped charge jets and KE rounds. The dynamic plate thickness is definitely also one part of the effects, which disturb shaped charge jets and KE rounds,but does not give the full story for the defeat mechanisms of ERA sandwiches."

 

"In a numerical example these diagrams should be explained. Using 270 mm as one typical Z0 value for the virtual origin of a shaped charge to an ERA sandwich, a jet tip velocity of 9 mm/ms and a cutoff velocity of vjc of 3 mm/ms under a typical NATO angle of 608, the dynamic thickness Ds of the plate flying with the jet ± rear plate ± is 206 mm and against the jet 63 mm, therefore in total around 270 mm. The used values correspond typically to an add-on reactive armour sandwich of equal layer thicknesses with 3/3/3 mm. Independent of the standoff against a 100 mm shaped charge such a sandwich gives a penetration reduction of 560 mm compared to the standard penetration of 800 mm. The perforation through a reactive armour plate means a reduction of 70%. But the dynamic thickness would give only a value of about 30%. Assuming a heavy reactive armour which is typically using thicker plates with slower velocities in the range of 0.4 mm/ms, the dynamic plate thickness is much less. According to Fig. 3 the sum of the dynamic thickness of the front and rear plates gives around 100 mm. This means a reduction of about 10% to 15%. But in reality it is again 70% and more. These numerical examples show that the dynamic thickness of the flying plates explains only partially the reduction effects of ERA sandwiches."

 

So the major reason why SCJs have a reduced penetration when interacting with ERA is because it is actually damaged and destroyed. A minor reason is that it has to penetrate the plate itself and deplete itself that way.

 

 

Compare you, genius of Sturgeonshouse forum, expert in terminal ballistics, who said this:

 

"Anyway, yes, the main reason why ERA/NERA works is due to feeding material into the jet. Since a penetrator can only penetrate a finite amount of armour, you can lower the thickness of main armour it can penetrate by feeding material (armour) into its path."

 

To Manfred Held, father of ERA:

 

"These numerical examples show that the dynamic thickness of the flying plates explains only partially the reduction effects of ERA sandwiches."

 

"the main effect comes from vaporising and sputtering of the passing shaped charge jet, as it touches iteratively the edge of the flying plates. This is summarised under the term deflection effect."

 

 

But I guess Dr. Held is just a senile window licking old man. What does he know? Curb your egotism and stop insulting people just because they disagree with you.

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@Bronezhilet, I give you permission to disengage with Iron Drapes. You have won the argument. You've provided more sources, documentation, and reasoning. At this point, there's nothing left for you to do, so take a victory rest.

@Iron Drapes, You have lost this discussion to Bronezhilet, because your density of sources, citations, and facts were low compared to the degree of negative attitude you displayed. I recommend you also take a breather, and work on refining whatever it is you want to say so that it comes across more intelligibly and politely. I also recommend just taking your lumps here and not forcing this issue with me, because if pushed to choose between you or Bronezhilet, well, you haven't been here very long and he has.

You both can revisit this technical discussion later, for now, as the Admin I recommend you both take some earned time off from the subject.

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23 minutes ago, Sturgeon said:

@Bronezhilet, I give you permission to disengage with Iron Drapes. You have won the argument. You've provided more sources, documentation, and reasoning. At this point, there's nothing left for you to do, so take a victory rest.

@Iron Drapes, You have lost this discussion to Bronezhilet, because your density of sources, citations, and facts were low compared to the degree of negative attitude you displayed. I recommend you also take a breather, and work on refining whatever it is you want to say so that it comes across more intelligibly and politely. I also recommend just taking your lumps here and not forcing this issue with me, because if pushed to choose between you or Bronezhilet, well, you haven't been here very long and he has.

You both can revisit this technical discussion later, for now, as the Admin I recommend you both take some earned time off from the subject.

 

I respect that you are the admin of this entire forum, so I will cease and desist. The truth is up to the audience to decide. I simply express my hope that the criteria for "density of sources, citations and facts" also includes the fact that I actually shared links to the papers I cited so that everyone can benefit by reading them, whereas Bronezhilet did not share a single link or give a page number, or even share the names of the papers he cited.

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5 minutes ago, Iron Drapes said:

 

I respect that you are the admin of this entire forum, so I will cease and desist. The truth is up to the audience to decide. I simply express my hope that the criteria for "density of sources, citations and facts" also includes the fact that I actually shared links to the papers I cited so that everyone can benefit by reading them, whereas Bronezhilet did not share a single link or give a page number, or even share the names of the papers he cited.

 

I see three links from you (which is good - we like links here, especially ones to real papers - so a sincere commendation on that), and a citation of Kobylkin and Dorokhov, which Bronez cited first. I see 5 or 6 citations from Bronez, with no links but I assume one could easily find the papers themselves via Google or another resource. Beyond this, you were, in my estimation, a bit ruder, although Bronez towards the end also lost civility a little (that, I admit, was partly my fault - I told him he didn't have to be gentle with you). I also happen to be more well aware of Bronez's expertise in the field.

I am not an expert on the subject, so I'll leave it at that.

 

It sounds like you might have something to offer here, but in the future you'll want to keep technical disagreements as passionless as possible. It can be tough - you probably care about the subject. But Bronez does not know you, and I don't know you, so it's still important.

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