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1 minute ago, Sturgeon said:

 

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.

 

Thank you for being objective. My "resume" can be found here: https://thesovietarmourblog.blogspot.com/

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10 hours ago, Iron Drapes said:

A single glance at the equation already tells you that it will give you a ratio, not a figure of armour penetration.

How are you supposed to designate target penetration as a ratio?

Since the equation contains Ptot', which has a unit, multiplied by a ratio the answer most definitely has a unit too.

 

I love how you quote Held saying "But the dynamic thickness is only one of the reduction factors of ERA sandwiches." but you explain that as "it is a minor factor compared to the disruption and interference of the jet itself".

 

See the difference? Held says that dynamic thickness is one of the reduction factors while you claim he said it is a minor reduction factor. In his example he says that with an ERA sandwich that gives a reduction of 70%, the dynamic plate thickness is responsible for 30%. That's almost half of the total reduction. With multiple other effects being responsible for the other 40%. How do you manage to read that as "minor"?

 

Fact of the matter is that if the plates do not move into the path of the jet, ERA doesn't work. No interaction between plates and jet = no effect*. And since hydrodynamic penetration is a thing, you have to keep the plates moving into the jet.

 

6 hours 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.

Ask and ye shall receive, but thou hath not asked.

 

But since we're going to play the blame-game, it was you who started posting pictures without citations.

 

* Okay okay okay, the pressure wave from the detonation will have a tiny effect on the jet

 

Oh well. Back to work.

 

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5 hours ago, Bronezhilet said:

How are you supposed to designate target penetration as a ratio?

Since the equation contains Ptot', which has a unit, multiplied by a ratio the answer most definitely has a unit too.

 

As a ratio to the experimental result. Ptot will equal something like 0.983 Ptot' or 1.0143 Ptot', so one over the other will get you a ratio. Sure you could get a fixed answer, and that answer will be the new Ptot but adjusted for the new variable. You can't actually get Ptot from the equation. To do that, you'll need this: 

 

NYzG4WM.png

 

Pis useful for finding out the residual penetration, which is what we actually want to know, and Ptot finds out how much the jet penetrates, including the ERA itself, which is not actually a useful value for us anyway because Ptot is basically the penetration of the shaped charge warhead.

 

5 hours ago, Bronezhilet said:

I love how you quote Held saying "But the dynamic thickness is only one of the reduction factors of ERA sandwiches." but you explain that as "it is a minor factor compared to the disruption and interference of the jet itself".

 

See the difference? Held says that dynamic thickness is one of the reduction factors while you claim he said it is a minor reduction factor. In his example he says that with an ERA sandwich that gives a reduction of 70%, the dynamic plate thickness is responsible for 30%. That's almost half of the total reduction. With multiple other effects being responsible for the other 40%. How do you manage to read that as "minor"?

 

He also said:

 

"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."

 

But you choose to ignore it. So if the total effect of ERA can be expressed as a 70% reduction in the penetration of ERA, and various methods of identifying the factors in the reduction tell us that the dynamic plate thickness has an effect of between only 30% and 10-15%.... Yes, I consider that as a minor factor compared to the disruption and interference of the jet. It is not the primary mechanism of defeat.

 

5 hours ago, Bronezhilet said:

Fact of the matter is that if the plates do not move into the path of the jet, ERA doesn't work. No interaction between plates and jet = no effect*. And since hydrodynamic penetration is a thing, you have to keep the plates moving into the jet.

 

I never said that ERA can have an effect on a cumulative jet without any of the moving plates touching it, as if the plate simply disappears into thin air when it is touched by the jet. That is simply your imagination of what I am saying. I have said many, many times that the effect comes from the destabilization, disruption, interference, etc, etc of the jet as the moving plate impacts and cuts through it. Some of the effect comes from the thickness of the plate itself, yes, I never disputed that, because it would be stupid to do so, because no, I am not stupid enough to not realize that the plate itself has some thickness, and that moving it laterally across a jet or some other penetrator increases that thickness.

 

5 hours ago, Bronezhilet said:

But since we're going to play the blame-game, it was you who started posting pictures without citations.

 

Ask and ye sh- blah blah blah. And I wasn't even talking to you when I posted that. So in the context of this discussion, it has absolutely 0 relevance. Besides, the picture was from you, and you did not give the sources for any of the three pictures you posted. Don't make it harder for yourself.

 

 

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7 hours ago, barbaria said:

Why not both? Both disrupting the SCJ and feeding material into it? That's what I make out of it.

 

For a range of ERA plate thicknesses, jet velocities, angles and so on, disrupting the SCJ is by far the biggest mechanism. Feeding material into it is one of the reasons, sure, but it does not contribute to the effect nearly as much as the disruption effect. I predict that for some ERA like the Ukrainian Nozh with something like 2 kg of RDX, the disruption of the tip of the jet might already approach the same significance as the "feeding material effect". 2 kg really is a lot compared to many of the ERAs used in experiments, which have something like 0.2 kg of RDX or PETN or something, and let's not even mention the ERA block that got hit chain-detonating the ERA block beside it. 

 

We also have to take into account the fact that SCJs are not always continuous jets. Disturbance can cause it to break up and particulate. For example, in the armour array of an M1 Abrams, there NERA plates are located behind a simple spaced steel front wall. Impacting the front wall and emerging into the air gap behind it will cause an SCJ to partially particulate, and the behaviour of the jet will not be the same as a continuous jet when it impacts the NERA plates. Particulated jets will be easy to deflect by the moving plate of the NERA because the jet will tend to "splash" on the surface of the plate itself instead of going through, so sometimes there is very little penetration into the plate itself, and therefore almost no material being "fed". I suspect that you may see this at the end of a stack of NERA plates, when the jet is more or less expended. Older shaped charge warheads like the type you find on the old PG-7V (1961) are not so precise, and antiquated shaped charges like the Panzerfaust and RPG-2 are even more imprecise, so the jet is already a little particulated when it forms and hits the ERA, and less and less material is being "fed", so to speak. So for all intents and purposes, the value of ERA comes from disruption of the SCJ.

 

BTW I think we all should use "dynamic plate thickness" instead of "feeding material". The former is an established scientific term and it is more specific than the latter.

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1 hour ago, Iron Drapes said:

 

As a ratio to the experimental result. Ptot will equal something like 0.983 Ptot' or 1.0143 Ptot', so one over the other will get you a ratio. Sure you could get a fixed answer, and that answer will be the new Ptot but adjusted for the new variable. You can't actually get Ptot from the equation. To do that, you'll need this: 

 

NYzG4WM.png

 

Pis useful for finding out the residual penetration, which is what we actually want to know, and Ptot finds out how much the jet penetrates, including the ERA itself, which is not actually a useful value for us anyway because Ptot is basically the penetration of the shaped charge warhead.

What are you trying to say here? In a previous post you said that the equation 34 will give a ratio. It will not.

Just take a look at equation 26 too. If you check the units used in the formula, Phas a distance unit:

6e0f2250c5.png

You can do the same for equation 34 with the same result.

 

And actually, yes, we do want to know Ptot since that predicts the total penetration of the HEAT jet in the target. The standard penetration of the HEAT jet is called Pnom in this paper:

0aaac49f7a.png

 

Shit, they even give the equation to calculate the efficiency of ERA:
3a5f0ed37a.png

If Ptot is the penetration of the HEAT jet, and Pnom is also the penetration of the HEAT jet, that means that ERA has an efficiency of 0.

 

1 hour ago, Iron Drapes said:

He also said:

 

"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."

 

But you choose to ignore it. So if the total effect of ERA can be expressed as a 70% reduction in the penetration of ERA, and various methods of identifying the factors in the reduction tell us that the dynamic plate thickness has an effect of between only 30% and 10-15%.... Yes, I consider that as a minor factor compared to the disruption and interference of the jet. It is not the primary mechanism of defeat.

Of course, the 10-15% is from a test with a different type of ERA.

 

You're misreading Held here. 

 

Lemme quote him again so we don't have to switch between pages to read it:

Quote

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%.

Simply put, a HEAT jet with a standard penetration of 800mm had its penetration reduced by 560 mm, so its actual penetration was 240 mm. The expected reduction from the dynamic plate thickness was ~270 mm.

Now, I might be bad at maths at times, but 270 mm is still around 48% of 560 mm. So the dynamic plate thickness counts for 48% of the actual loss in penetration. How is that minor?

 

1 hour ago, Iron Drapes said:

Ask and ye sh- blah blah blah. And I wasn't even talking to you when I posted that. So in the context of this discussion, it has absolutely 0 relevance. Besides, the picture was from you, and you did not give the sources for any of the three pictures you posted. Don't make it harder for yourself.

 

So first you take an unsourced picture at face value, and then you repost it trying to strengthen your argument? Nice meme.

 

I didn't even use it in an argument there, I posted it because it was interesting. If sourcing interesting stuff/pictures is a requirement now... well, lets just say Loooser has a fuckton of work to do.

 

Also

13 hours ago, Iron Drapes said:

whereas Bronezhilet did not share a single link or give a page number, or even share the names of the papers he cited.

Well fuck me sideways, I'm not allowed to reply when someone talks about me in a public forum? What did you expect by trying to play a blame game with an admin on a public forum?

 

1 hour ago, Iron Drapes said:

For example, in the armour array of an M1 Abrams, there NERA plates are located behind a simple spaced steel front wall. Impacting the front wall and emerging into the air gap behind it will cause an SCJ to partially particulate, and the behaviour of the jet will not be the same as a continuous jet when it impacts the NERA plates.

But... we had already established that HEAT doesn't really give a shit about a simple plate? In the following photo the jet of a 56mm shaped charge is still smooth and intact even after penetrating two 3 mm thick steel plates:

1de3aa1eb4.jpg

(Yes, I know this is a NERA array, but non-angled NERA might as well be a simple plate)

 

It's from here by the way: http://onlinelibrary.wiley.com/doi/10.1002/prep.201200172/full

 

1 hour ago, Iron Drapes said:

Particulated jets will be easy to deflect by the moving plate of the NERA because the jet will tend to "splash" on the surface of the plate itself instead of going through

At hydrodynamic velocities the strength of both the penetrator and armour may be considered to be zero (https://www.amazon.com/Armour-Materials-Paul-J-Hazell/dp/1482238292), which means that it's literally impossible for the jet to "splash".

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Now I'm wondering if you are just trying to spite me because you won't let go of your preconceived notions or if you really have something to say. Held said that the main effect comes from vaporising and sputtering of the passing shaped charge jet, as it touches iteratively the edge of the flying plates. If there is a nearly 50/50 split between the contributions of dynamic plate thickness and jet disruption, he would not attribute greater importance to one mechanism over the other. I am going to sleep. If you want to know something, ask Held.

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6 hours ago, Bronezhilet said:

Unfortunately, Manfred Held passed away in 2011. Asking him is going to be a little tricky.

 

Or are you perchance trying to tell me to kill myself?

I hope you appreciated my attempt at humor.

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I kinda forgot to ask but, what exactly is your field of work?

Are you actually developing munitions in your respective country, or did you take this research as a hobby?

 

Also, what degree of education do you have on the subject? 

 

I admire your level of knowledge greatly.

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11 hours ago, Mighty_Zuk said:

I kinda forgot to ask but, what exactly is your field of work?

Are you actually developing munitions in your respective country, or did you take this research as a hobby?

 

Also, what degree of education do you have on the subject? 

 

I admire your level of knowledge greatly.

I'm a mechanical engineer. At the moment weapons research is a hobby, but I am trying to make it my job. Sadly we don't really have a proper weapons industry.

 

Oh, and we have horrid weapons laws, so I can't actually make/test anything.

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55 minutes ago, Bronezhilet said:

I'm a mechanical engineer. At the moment weapons research is a hobby, but I am trying to make it my job. Sadly we don't really have a proper weapons industry.

 

Oh, and we have horrid weapons laws, so I can't actually make/test anything.

And where do you live? Belgium, I recall?

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