Anti-Tank round = Big hole, or little hole?

Discussion in 'Weapons, Equipment & Rations' started by chrisg46, Sep 23, 2011.

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  1. chrisg46

    chrisg46 LE Book Reviewer

    This thread (http://www.arrse.co.uk/weapons-equipment-rations/169776-why-rifle-recoil-so-low-3.html#post3965776) reminded me of another item of curiosity that has vaguely bothered me over the years.
    Generally, in films you fire an anti tank weapon at something results in an almighty explosion (like those REALLY powerful grenades that Hollywood issue as well).
    Similarly, in FIBUA/OBUA/FiSH & CHiPS or whatever its called now, i have been taught that to create an entry point in the side of a house, launch a LAW 94 etc to blow a mousehole. All well & good.

    However, I understand that a HEAT round punches a small hole in the target, then molten metal is effectivly injected through the whole and bounces around the space inside reducing the occupants of that space to lumpy bits of Spaghetti Bolognaise.

    Therefore, if you launch a LAW94 or I-LAW at the side of a house, you will create one hell of a bang and upset anyone on the other side of the wall, but upon arrival at the wall, you wont find a mousehole but you might get a letterbox...
     
  2. Not strictly true although some of the theory is right. A/Tk rounds can be either HESH or HEAT. HESH is old school, but still highly effective as it lands a large slab of HE on the the target. HEAT rounds do, as you say, rely on shaped explosively formed projectiles (EFP) often created from the copper cone surrounding the expolosive charge. Howver they are not quite as clinical as you imply and there can be a high degree of fragmentation caused locally around the point of impact. Additionally if the target is relatively soft - mud wall, old brick or sandbag then the warhead will not act in exactly the way it was designed as the speed of its arrival will be so great that it will penetrate the target itself and the designed "stand off" distance of the projectile will be so small that the main effect may not be exactly determined. It might function as designed and create a jet of EFP with the additional "normal" fragmentary balst or it may be an internal explosion of the whole charge within the target itself, causing a sizeable hole. this why you may see LAW type shoulder fired ATk weapons deployed in ISAF, being used in the anti bunker or door entry role.
     
  3. You are perfectly correct that shaped charges are somewhat sub-optimal for creating entry points and knocking down buildings, as is fin & sabot.. HESH is really the only AT projectile that has a more general purpose effect.

    You can de-tune shaped charges to give more blast effect and also add fragmentation jackets etc to improve anti personnel effects, however this is at the expense of the anti armour performace. As a result, spot the recent introduction of a range of anti structure weapons...

    The old RPG 7 HEAT warhead is extremely efficient at armour piercing but has limited blast & AP effects. There are a range of alternate projectiles for this weapon system to produce other effects.. the PG7 AP round, the Chinese "Bouncing Betty" and Thermobaric blast rounds..
     
  4. I recall a deomnstaration video of terminal effects of rounds back in hte 1980s which showed quite clearly that firing a CG 84mm at a building didn't create a very big hole in the wall.
     
  5. Outstanding, I'm afraid that you are confusing HEAT and EFP warheads. An EFP fires out a metal slug at very high velocity that remains effective at greater range from the point of detonation. A HEAT warhead discharges a jet which is highly penetrative, but which is effective only at a short distance from the point of detonation (determined by charge cone diameter, geometry, mass and chemistry). Therefore while similar(ish) in design, they are quite different in their effect.

    As to the original question, I have a little bit of practical experience in this area. The effect you get is largely determined by the type of structure you are shooting at.

    If HESH is fired at a soft wall (such as very poor quality single breeze block), it has a tendency to pass straight through without functioning and just leaving a fist sized hole in the wall. If you fire it at a much harder material like thick hard baked mud or even stone or concrete slab, you can start to get 'better' results. It is a bit hit and miss, by trying to put in a mouse-hole you could end up knocking the whole building down or you might just give your opponent a new firing point through the wall.

    HEAT tends not to fail to detonate in the same way as HESH (it does not need to deform the case in order to function). The jet will indeed make a deep but very narrow hole through the wall. In addition to the jet, a hollow charge will cause blast (in the same way as any other explosive charge), it is this which (following the jet) will cause damage to the wall. Again the exact effects in terms of structural damage/mouse-hole size will depend on warhead performance and the building material.

    Add to this the effects of a tandem warhead and some clever fusing and the results become even less predictable.
     
  6. To further B-C's comments for HEAT look up Monroe Effect and for EFP - Miznay Schardin Effect.

    HEAT warheads are difficult to manufacture due to the tight tolerances involved to produce best effect.

    EFPs don't require such tolerances hence their use in IEDs, but then they only have a fraction (about 10%) of the penetration of HEAT.
     
  7. SOOOO firing enough heat rounds at a house to produce a mouse-hole might kill everyone inside and or set it alight cause it too collapse and the down side is?

    can't see why I was never picked for hostage rescue training ?
     
  8. Not really..

    The explosive effects from a HEAT round all occur outside the building.. Even from something as large as a 120mm round, the jet is only about 10 - 20mm wide. Although there will be some some frag & blast, this will generally be along the line of the jet..

    If you want to blow out a building, the best way is to explode a blast warhead in the centre of the void. There are a number of ways to do this..

    1. Use an impact fuze with a delay - all our conventional artillery and mortar HE rounds have this feature.

    2. Use a tandem warhead. First warhead (usually shaped) bores a hole, second warhead, optimised for blast, timed to detonate in the centre of the void flattens the building. Quite a few of these around.. For example the Russian RShG2 (pronounced "Arrshooga Dva") sporting a cheeky thermobaric second stage is fairly typical...Modern Firearms - RShG-2
     
  9. 3. If all else fails a Boeing 767 usually does the trick.
     
  10. Correct tool for the correct job. If you are having difficulty cracking the nut, try a bigger hammer.