Shaped Charges

Discussion in 'Sappers' started by Oyibo, Jan 17, 2013.

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  1. I was chatting to my boss earlier this week about an RPG strike where we operate and tried to explain how shaped charges work. It turns out that he, being an ex (civilian) engineer was very knowledgable on the subject - he had been trained to use shaped charges to bore through rock.

    I had always thought that the jet of molten soft metal penetrated things (armour) but he told me that it was the extreme pressure from the shockwave that caused heat that melts armour or rock. Sounds logical - does anyone know if this is actually the case, or a combination of the two?

    Neither of us really knew what role the metal in the cone played - I remembered most munitions using copper in the cone and he, with an industrial background, recalled compressed powdered metals of various types and mixtures, depending on the rock to be penetrated, being used. Can any of Arrse experts on the subject enlighten us on the interaction of pressure and molten/vapourised metal (I have googled munroe ffect with little success).
  2. First used at Eban Emael apparently.
  3. AIUI its the metal ( usually copper?) that is turned into hot nasty plasma with a hell of a lot of KE behind it.
  4. @ PX4 - that was my understanding

    @BB - that was my understanding as well. But my boss, who is extremely knowledgable about pressure and heat having worked in oil & gas for a few decades, insisted otherwise. I suspect that the copper slug is Miznay Shardin rather than Munroe effect.
  5. Google the Munroe effect.

    Interesting stuff.
    • Like Like x 1
  6. To go really in depth look into the Munroe or Neumann effect.

    The liner (usually copper) is an enhancer and is there to focus the effect of the detonation wave. The cone inverts into a jet which punches a hole through the material. This is kinetic, not pyretic.
    • Like Like x 5
  7. Agreed, but I cannot really find explantations of the interaction of pressure and the molten metal jet. My intuition says the presuure lelts it ant the jet clears the molten target. I just can't find a definitive answer - let alone why different metals work better with certain targets.
  8. The copper of a shaped charge isn't molten as such, it just behaves like a liquid.
    At the kind of speeds we're talking about - 8km/s or so - the interaction of the jet tip with the target generates such pressure, that the yield strength of both materials is exceeded by enough of a factor to make strength essentially irrelevant. In this case - known as hydrodynamic penetration - the only things that really matter are the material densities, and length of the jet.

    Off to chortle at The Big Bang Theory now...

    Sent from my GT-S5830i using ARRSE mobile app
    • Like Like x 1
  9. There you go
    Discovery Channel: Shaped Charges - YouTube

    Remember the old days when we used to make improvised shaped charges out of a brandy bottle (Inverted vase) and 3 six inch nails taped to it to give it stand off.
    • Like Like x 3
  10. Munroe is the action of the blast force concentrating pressure waves from detonation by having a hollow on the face of a charge. Misznay is an expansion of the same effect by having the hollow spherical and lining it with metal.
  11. Thanks Dingerr,

    Does the copper clear the molten (caused by extreme pressure) target?
  12. I don't understand the question.
    • Like Like x 1
  13. My boss' understanding was that extreme and focussed (from the shape of the charge) pressure caused heat that would make the target melt. I had heard of improvised shaped charge projectiles that used steel cones or no metal cone that just did not work, so I was wondering what role the cone played if the target had already melted. My thought was that the jet of molten malleable metal would hose out the target molten material.
  14. I think he wants to know, what actually causes the penetration. Is it the pressure wave or is it the soft molten copper?

    Its the copper isnt it? High velocity negates how soft it is and it will go through by shear speed of force.
  15. No it's a jet. The copper follows through as a slug. An added bonus when hitting armour.