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Sturgeon's House


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Everything posted by Bronezhilet

  1. General news thread

    Since I don't think we have a general news thread, I decided to make one. Dump all news in here that doesn't fit other threads. Soooooo... an EgyptAir Airbus A320 just got hijacked. http://www.bbc.com/news/world-middle-east-35915139
  2. Contemporary Western Tank Rumble!

    More about how this works can be found in this paper: https://www.researchgate.net/publication/281489377_Theoretical_Study_of_a_Diesel-Filled_Airtight_Structure_Unit_Subjected_to_Shaped_Charge_Jet_Impact If you want the full paper, PM Me.
  3. Hi, I'm MrCatKK and I cannot Post

    Every time I think I've met the dumbest person I'd ever meet, there will be *someone* going to prove me wrong.
  4. Since not all AA is mechanised, I put it in the Aerospace section. If it belongs somewhere else, please move. Patriot system: National Advanced Surface-to-Air Missile System 2 (NASAMS 2): Fennek Stinger:
  5. Is here anybody from "thesovietarmourblog"?

    Yeah. Dude told me to kill myself after he couldn't 'win' an argument with me. Said all kinds of silly things about me, mainly about how I knew jack shit. So I kindly asked him why he was using me as a source on his blog. Sadly he was just banned when I said that. But he did remove me as a source from his website!
  6. Contemporary Western Tank Rumble!

    He knew what he was doing, and did it multiple times. Did you not read Jagdika's topic?
  7. Contemporary Western Tank Rumble!

    Considering it turned out WaifuTrucker is a lying dick, I'm not trusting this one. Especially since it has some of that "oooh look at me typing text and blacking it out im so secret" stuff.
  8. Contemporary Western Tank Rumble!

    Registering and logging in worked for me. Also Google Translate doesn't work on pictures.
  9. Contemporary Western Tank Rumble!

    I can't see the pictures in either of those links, but I did register at the forum, maybe that helps.
  10. Contemporary Western Tank Rumble!

    Considering this was posted by someone new, I had it checked with a translator I know. And yes, this is about cameras, not tanks. Also you can say bullshit and fuck on this forum, welcome to the club.
  11. Contemporary Western Tank Rumble!

    So which one is it, do you have the full document or not?
  12. Contemporary Western Tank Rumble!

    So basically Damian is having a meltdown. What a shock.
  13. General Mechanised Equipment

    Since I didn't want to put non-fighting vehicles in the General AFV thread, here's a topic dedicated for non-fighting mechanised equipement. And to kick it off, a Centurion Bridgelayer:
  14. No, it's a mobile bridge they were using to try and cross an anti-tank ditch on the eastern side of the Ghouta pocket.
  15. No, Nozh doesn't work as advertised

    @Collimatrix @Mighty_Zuk @SH_MM @LoooSeR @Militarysta @Xlucine Yeah I took 'some' liberties with the jet, but that mainly has to do with this being a rough first look at Nozh, I'll do a more properly shaped jet later. tl;dw: Yes, a copper jet can cut through a wolfram penetrator but the jet is not nearly long enough. Edit: This is also a frictionless simulation so the jet penetrating the steel plate doesn't slow it down at all. All in all, this is a best case scenario for Nozh.
  16. So, if you're reading this I assume you know what Nozh is and how it's supposed to work. Just a quick tl;dr to refresh your minds: Nozh is supposed to work by cutting a penetrator with the use of multiple shaped charges, like this: The thing is that it cannot work as advertised, for a plethora of reasons. Most of these reasons have to do with the formation of a shaped charge jet. So lets go. The thing I realised when looking at Nozh is that I usually assume that shaped charges are initiated correctly. That is to say, on the centre axis exactly in line with the 'point' of the liner and a bit behind the liner to get a uniform shock front going. This is not the case with Nozh. Both the 'primary' charge (the one being actually hit by the penetrator) and the secondary charges are initiated badly, but the primary moreso than the secondaries. The problem with this is that shaped charges are ridiculously sensitive to position of the initiation point. And I do mean ridiculously sensitive. A drifting jet will already be formed with an initiation point that is less than 0.01 CD off-center. And the further off-center it is, the higher the drift. (Both pictures from "The influence of asymmetries in shaped charge performance", by Ayisit) It gets even worse when you ramp up the eccentric initiation even further: (Both pictures from "Studies of Shaped Charges with Built-In Asymmetries. Part 11: Modelling" by Brown et al.) As you can see there is quite the amount of drift present (and it's drifting away from an incoming penetrator). But this is still a shaped charge that is otherwise completely intact. So we'll look at damaged shaped charges as well. And oh boy. So since the ERA is getting hit with a penetrator the ERA casing will get deformed and most likely damage nearby liner charges. Not only that, the detonating liner charges will most likely damage the liner charges next to it too. So lets see what happens when the explosive filler in a shaped charge is damaged: (Pictures from "Effect of Fragment Impact on Shaped Charge Functioning" by Chanteret) Not that exciting, it has the same effect as off-center initiation; the jet drifts. But what happens when the explosive *and* liner are damaged? (Pictures from "Effect of Fragment Impact on Shaped Charge Functioning" by Chanteret) That a significantly worse jet, there's no coherent tip and there isn't really a slug being formed either. That's pretty bad. The most important part of the Nozh ERA (the tip) is basically non-existant. But it gets even worse when you introduce actually moving projectiles instead of just static damage: (Pictures from "Effect of Fragment Impact on Shaped Charge Functioning" by Chanteret) There's basically no jet and there's no coherent slug being formed. Effectively, this charge is close to useless. But lets look at a couple more results: (Pictures from "Effect of Fragment Impact on Shaped Charge Functioning" by Chanteret) This is what Chanteret himself has to say: So a proper shaped charge can have a penetration loss of more than 70%. This is significant considering these are proper HEAT charges, not EFPs like the ones used in Nozh. I'll get back to that later. But all these things directly affect the shaped charge, what if we introduce obstructions in the liner cavity? In theory that means that a proper HEAT jet can't be formed, and in practice...: (Pictures from "Investigation of Several Possibilities to Disturb the Jetting Process of 40 mm / 60° Charges" by Voumard et al.) ...it's exactly what happens. Sadly I haven't been able to find a study which combined all these defects, but I guess we already know the results of those tests: "No jet, only dust". Now apply all these things to an EFP (which the liner charges in Nozh are). They are hemispherical liners, which, unless you know what you're doing, have lower penetration than conical liners. They're also slower so they'll intercept the penetrator at a later point than conical liners. And they're drifting away from the penetrator because of off-center initiation. And they're most likely damaged liners so the jet formed will inherently be worse. And the jet formation will probably be obstructed, so the jet can't even form properly in the first place. And the formed jet has to penetrate a thick 'flyer' plate, so the tip velocity will be even lower. And then a slow, eroded and strongly perturbed copper jet will intercept a wolfram penetrator. Now, how was that supposed to cut a penetrator again? ...yeah I realise this became more of a rant about how ridiculously sensitive shaped charges themselves are and less about how bad Nozh is. And I didn't even talk about everything that influences the formation of a jet. What about grain size? What about cavities in the explosive filler? What about an explosive filler detached from the liner? What about a liner with an asymetric thickness? What about an explosive filler detached from the casing? All of these things have a negative effect on the jet formation. As we already know HEAT warheads in rockets are worse than in ATGMs (afaik due to a cheaper manufacturing process), there is no way that the liner charges in Nozh are of high quality. Nozh is bad. You also know its bad when you look at this picture from a patent: Now tell me, what's wrong with that drawing? So why does Nozh 'work'? Well, it's a relatively giant amount of explosives with a thick flyer plate. Soooo.... it's basically 'Heavy ERA'. REALLY REALLY HEAVY ERA. Nozh just gets one giant fucking "...what?" from me. ....discuss away gentlemen, because I think @Collimatrix and I are the only ones that claim that Nozh doesn't fucking work.
  17. No, Nozh doesn't work as advertised

    A rough model of a linear shaped charge about to hit a long rod penetrator after penetrating a 15mm thick steel plate.
  18. No, Nozh doesn't work as advertised

    So I have been doing a bunch of simulations and indeed Nozh does not work as advertised. But it doesn't due to the reasons @Collimatrix and I predicted. I'm going to do some more simulations to get a clearer picture. To be continued...
  19. WoT v WT effort-thread

    I like where this is going, but fuck the grinds.
  20. At the request of @anwaralsharrad a topic about non-initiating precursor shaped charges. Basic principle of non-initiating precursors As the name implies, these are specialised shaped charges designed to not initiate something, which in this case is an ERA sandwich. The purpose of this is to punch a hole through the ERA sandwich for the main charge to go through, without setting the ERA off. Achieving this means that the detonation of the ERA sandwich cannot influence your projectile in any way shape or form. The explanation on how this works is fairly simple: Every energetic material (explosive) needs to be initated, if it isn't initiated it will act like any other material when hit by a projectile. In our case the initiation is done (or not done) via an impact. For an explosive to not initiate by impact, the impact energy needs to be lower than the critical energy* of the explosive. So you basically throw something at the ERA sandwich fast enough to punch a hole through it, but not fast enough to introduce critical energy in the explosive. This is usually achieved by using a special liner material, usually something lighter than copper (in theory you can make the jet slower to make it non-initiating, but then the main charge might catch up with your precursor jet, which you don't want). I've seen PTFE thrown around as a liner material for a non-initiating precursor warhead. The formula for kinetic energy is Ek=0.5*m*v2,, the kinetic energy of something is half the mass multiplied by the square of its velocity. So to lower the energy you can either go lighter or slower. * The impact/shock initiation point of explosives can be quantified by multiple units like J*cm-2, v2d, u2d, ρv2d, √ρv2d, Pd, and probably a whole bunch more. In this topic I will keep it simple and try to not use units. Things that influence non-initiating precursors However, it is quite tricky to get right since a plethora of factors influence the initiation point of an explosive. For starters, the type of explosive used in the ERA block is important: (Table from "A General Model for the Shock Initiation of Explosives" by F. E. Walker and R.J. Wasley) As you can see, explosives can have wildly varying critical energy points. Although these values are for pure explosives and not the desensitised explosives used in ERA, but this should give you an idea about not all explosives being equal. So a precursor might be non-initiating versus one type of ERA, but not versus another type of ERA simply because they use different types of explosives. A different graph showing the same thing: (Figure from "The Legacy of Manfred Held with Critique" by EV2 Florian Bouvenot) Furthermore, the impact velocity to initiate an explosive changes when the explosive is protected by a barrier of another material. The effectiveness of this barrier, which in the case of ERA is a flyer plate, depends on its thickness: (Figure from "The Legacy of Manfred Held with Critique" by EV2 Florian Bouvenot) In this graph everything above the line means "Boom" and everything under it means "No Boom". So to initiate an explosive protected by a barrier, you can either go faster, or go heavier. And again, this means that a non-initiating precursor might not be non-initiating because one type of ERA might have a thinner flyer plate than an other type. Even the material used for the barrier has an effect: (Figure from "The Legacy of Manfred Held with Critique" by EV2 Florian Bouvenot) Again, a non-initiating precursor might be an initiating precursor depending on the material of the flyer plate. There has been research about using glass or ceramic flyer plates. It might be that a precursor that's non-initiating versus a steel flyer plate, is initiating versus a glass flyer plate. Another thing to take into account, is whether or not the explosive is confined on all sides. For example, Nozh has a non-uniform confinement, so Nozh might react differently to a non-initiating precursor. The effect looks like this: (Figure from "The Legacy of Manfred Held with Critique" by EV2 Florian Bouvenot) But the most important one for us, is projectile material: (Figure from "The Legacy of Manfred Held with Critique" by EV2 Florian Bouvenot) As you can see, the lower the material density, the faster the projectile has to go to initiate an explosive. This is what we want, because we want to punch a hole without initiating an explosive. However, a lighter material also means that it has less penetration compared to a liner with a heavier material. ...but a lighter material can be accelerated to higher velocities, which means a higher penetration than a slower jet with the same density. So basically, whether or not a non-initiating precursor is actually non-initiating depends on a significant amount of variables, each of which influences the other. Basically it's a giant mess of variables to keep an eye on, but the desired result is clear: Punching a hole through a metal-explosive-metal sandwich without setting off the explosive. After that you can throw whatever you want through that hole without having to worry about setting off an explosive, which means that you can use the best penetrator you can make. ... @anwaralsharrad does this answer your questions? If not, feel free to ask anything.
  21. Syrian conflict.

  22. Syrian conflict.

    Well hello there @Collimatrix
  23. Shit those jackets are old. That postal service last used the PTT name in 1998.