Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!shadooby!samsung!usc!cs.utexas.edu!tut.cis.ohio-state.edu!att!cbnews!military From: tiwasawa@netxdev.DHL.COM (Takashi Iwasawa) Newsgroups: sci.military Subject: Re: HEAT shell question and proposal. Summary: Not likely to work. Keywords: HEAT, Reactive armor, Blazer Message-ID: <12888@cbnews.ATT.COM> Date: 8 Jan 90 05:11:31 GMT References: <12756@cbnews.ATT.COM> Sender: military@cbnews.ATT.COM Followup-To: sci.military Organization: NetExpress Communications, Inc. Lines: 113 Approved: military@att.att.com From: tiwasawa@netxdev.DHL.COM (Takashi Iwasawa) In article <12756@cbnews.ATT.COM> gahooten@ames.arc.nasa.gov (Greg A. Hooten) writes: > > >From: gahooten@ames.arc.nasa.gov (Greg A. Hooten) > >I was reading some information about HEAT rounds lately, and >was wondering if this idea has been tested. In the article, >it was stated the spinning an HEAT shell caused it to lose >penetration ability, this makes sence, the gass would have a >tendency to spin as it fired, and lose energy more quickly. Actually, most shaped charges have a solid liner that forms a molten jet when the shaped charge explodes. This molten jet provides much more penetration than just the gases from the explosion. >So, they moved to a smoothbore gun. This prevents the spin, >and thus produces greater penetration. Then came this box >armour with a charge in it that would explode when the core of >the heat shell melted (that is essentially what happens) >through it. This explosion disrupted the molten jet and >prevented extensive penetration. This was first used operationally by the Israelis, who called it Blazer. The generic name for the concept is reactive armor. > The problem then is to again >allow the warhead's shaped charge to seal against the actual >armour and before detenating rather than having it detenate >against the boxlike covering allowing the jet to be disrupted. > You don't want the shaped charge to be right up against the armour, because the molten jet needs time/space to form. I don't have my references here, but I think that for precision formed shaped charges penetration increases with standoff distance (distance from armour to forward end of shaped charge) up to 5 or 6 charge diameters. For a TOW with the 6 inch warhead, that means 25 or 30 inches, ideally. That's why the new TOW warheads have long spikes that stick out in front; they increase penetration by increasing standoff, though they can't be long enough to be optimal. >Has anyone tried to marry a hard cap onto the top of a heat >round? In essence, what I see as advantageous it to penetrate >the box armour with a hard penetrator that will get through >that and any of the front of the 12-15 " of armour on the >front of a t-80, then as the penetrator begins to slow, the >collapes of the penetrator triggers the HEAT round. It would >be a combination of a penetrating round and HEAT. The >penetrator gets past the box, and the HEAT can defeat the >standard armour. > >This seems too easy to me, but I could not think of any >technical reasons why it would not work, only some unknowns. >Can the penetrator get a wide enough hole in the box (I wish I >could remember what the stuff is called, ah, REACTIVE(!), what >a dolt.) that the HEAT would not set of an explosion that >would ruin the jet? > This probably isn't workable because: 1. The hard penetrator and structure to hold it at the desirable standoff distance is heavy. HEAT is used instead of a kinetic penetrator (which is much less affected by modern armour devel- opments like Chobham armour and reactive armour) because it is light and doesn't need high velocities (which means more weight in launcher or propulsion system), so this is very undesirable. 2. If the hard penetrator is big enough and moving fast enough to push aside enough of the reactive armour, it might set off the reactive armour. Admittedly, the Israelis claim that rifle bullets won't set off Blazer, so maybe (a BIG MAYBE) this is not a problem. 3. The HEAT warhead isn't guaranteed to hit the enemy armour at right angles. In fact, HEAT warhead designers spend a lot of time trying to make sure the warhead goes off even when it hits at a shallow angle. The addition of a hard cap and the delay in initiation of the fuse will almost certainly cause glancing hits to deflect or not go off at all. 4. Now, assuming the hard penetrator has shoved a hole in the reactive armour and the shaped charge has gone off properly, the molten jet has to go through your hard penetrator before it can even start to attack the enemy armour. Even worse, if the enemy doesn't have reactive armour, you've degraded your penetration to no purpose. >The other problem is that it may be too short a range, though >it shouldn't unless the reactive armour is thicker and more >resistant to penetration than I think. > I don't understand this part. The reactive armour is just a slab of plastic explosive cased in light boxes, I think. >Any comments? Please. > >Greg Hooten I hope that you find my comments useful. I am solely responsible for my comments; neither my company nor the US government bear any responsibility or credit for them. If I've made any mistakes, I'm sure someone on the net will tell me in no uncertain terms :-) Takashi Iwasawa Net Express Communications, Inc. Suite 300 1953 Gallows Road Vienna, VA 22182 (703) 749-2768 (work) (703) 742-6631 (home) tiwasawa@netxdev.UUCP