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August 23, 2004

Maintenance day, continued.

As mentioned earlier, yesterday was Maintenance Day at Castle Argghhh!, with much dusting, checking of rust-proofing, some rearranging, and, perhaps most importantly, some poking in long-overlooked corners.

One of those corners was the Ordnance Closet, wherein the Armory's store of artillery and tank projectiles, rockets and bombs, which are not normally on display out of space considerations (should we ever remember to buy lottery tickets and those, winning ones... watch out! Sadly, I doubt the Arsenal numbers any sugar-daddies or -mommas among it's readers). We were mildly distressed to find this, buried in the far-more-damp-than-I-realized corner of the closet. Looks like I need to either add a, or re-site the existing, de-humidifier.

So, as I was gonna hafta deal with it anyway, I decided it was time y'all learned more than you wanted to know about Dual Purpose Improved Conventional Munitions - DPICM - which I will punish you with in the Flash Traffic.

When I was a young studly Lieutenant in Germany, and Dusty a slightly older "Mud Mover" (and was kindly providing a guaranteed lunch break at Graf with the noon cease-fire so he and his ilk could Move Mud) the Soviet Union still existed. Yes, Virginia, there really was an Evil Empire squatting sullenly on the east side of the Iron Curtain, behind the Ephel Duath mountains, in the land of Mordor, where the shadows lie. Er, Eastern Europe.

Anyway, there we were, with the many echelons of Soviet and Pact armor formations dancing in our uneasy dreams. How to deal with all those tanks? Of the many things we developed to deal with them - I'm going to talk about one, DPICM, and, the M483 cargo carrier round which delivered them. (Yes, Virginia, the Army sold these things off as surplus (they're inert, weigh about a 100 pounds, and only dangerous to your foot should you drop one) - I got this from the surplus store out by the LA International Airport (Lawton Area International Airport, that is.))

DPICM was developed to extend the idea of cluster munitions to artillery - as a way to get a more lethal bang for your buck, especially when dealing with armor. While High Explosive rounds are effective against tanks, at least 155mm and larger - they still have to hit pretty close, and absent a direct hit (not likely with indirect fire, except as a statitistical anomaly) they only disable - breaking road wheels and tracks, taking off antennas, etc - all easily repairable (well, unless you are the one breaking track, anyway). While that's fine for taking them out of the fight in the main battle area (MBA), where you can follow-up with direct fire at some point, we were looking for ways to kill tanks with artillery, both in the MBA and before entering it, and via missiles, at even greater distances. We didn't want to create a pure tank-killing/bunker-busting round (like the Copperhead) as we still needed to be able to deal with infantry and soft targets, and didn't want to swap out too many of our rounds out of the basic load for that purpose. We needed to keep standard HE M107 as well, to deal with things like obstacles, buildings, etc, as well as places like urban terrain and woods/jungle, where the bomblets get hung up in the trees, pre-detonated by the roofing, etc.

So we developed what we in the business call a 'dispensing submuntion'. A little bomblet inside the carrier round.

As you can see, the sub-munition consists of a small shaped charge, sufficient to blow through the top of the tanks then in service (that's where the armor is thinnest) and while reactive turret armor will defend (at least the first time) against these, the decking covering the engines won't. It's capable of penetrating 2.5 inches of rolled homogeneous steel armor and a *classified* thickness of composite armor. It has a little streamer that is released when the safety releases as the bomblets separate upon dispensing. This serves to stabilize the round (shaped charge down) and arm it. The casing is fashioned from material calculated to hold together long enough to form the jet of the shaped charge, then it breaks apart - creating fragmentation to annoy any soft, chewy infantry in the vicinity.

These bomblets are stacked in the round, one on top of another, for a total of 88 bomblets (the long tube on the left is actually the dummy filler that goes into an MLRS rocket to simulate the bomblets - we don't shoot DPICM in training!)

As Iraqi soldiers found out in Desert Storm, the stuff works pretty well. Actually, if I recall correctly, the Egyptians and Syrians found out too - one of the emergency supplies we delivered to the Israelis in October 1973 was stocks of the brand-spanking-new DPICM rounds initially intended to move into stockpile for USAREUR (US Army, Europe).

PEO Ammo has a little video of DPICM (in simulation). Do them (and yourself) a favor, right click and download. (Playback quality is enhanced and bandwidth suckage reduced if you do that.) I'll try to find some actual video, too.

The round is pretty simple, all in all. Put on a time fuze, set it for the proper height-of-burst based on range, and fire it. At the appropriate time, the fuze functions, kicks out the base of the projectile, and the spin of the projectile dispsenses the submunitions, giving an elliptical pattern over the target aread, the width and length of the ellipse determined by the height of burst and slope of the trajectory - regardless, it's greater than standard HE, and more effective.

As an example, the rule-of-thumb for an MLRS rocket was around 800 meters long by two hundred meters wide, with safety considerations.

This brings up another problem. DPICM is a very efficient round, and the sub-munitions have self-destruct fuzing - but there is a still a dud rate of 1-3 bomblets per 100. There are 88 in one round. So, a three-round volley from a battalion of 18 guns yields 142 or so un-exploded rounds, creating, in effect, a very low-density minefield. While Abrams and Bradleys could deal with that, HMMWVs and other wheeled vehicles would not. Not too mention crunchies on foot. It's a very real problem, as this excerpt from a Gulf War diary relates:

25 Feb 1991 Another gray day. Had TOC duty from 1900-2400 last night. Nearly comatose. No coffee, raining. Moving the TOC forward, we're caught in a DPICM area. Driving slow, looking for bomblets, don't want to hit any. Passing abandoned bunkers and a burned out truck. Craters everywhere. S-2 captured a Russian truck! AK-47s everywhere. TOC NT725510 Saw my first live mine. Just got word that another soldier was killed by picking up a DPICM bomblet, 3 critically wounded. We have to be very careful, everywhere we drive. 1600-about to get comfy for the night when we got word of JERIMIAH III.

The whole thing is worth a read, btw.

Artillery ammunition choices were restricted in Operations Enduring Freedom and Iraqi Freedom over dud-rate considerations, as well. The problem with AF cluster bombs is worse, with dud rates among the older weapons well up into the 25% range, leaving a heck of a UXO problem where they were used. They're effective as hell, but you have to take into consideration what the battlefield is going to be like after the battle, too.

Last, but not least - dispensing submunitions are not a new idea. Major General Henry Shrapnel of the British Army developed them in the late 18th century, as these examples of US Civil War shrapnel rounds show.

Which brings to mind a little technical thing of mine. On a purely technical note, what most people call 'shrapnel' is actually fragments. Shrapnel is more properly applied to submunitions contained in the shell - like Shrapnel's musket balls in a cannon ball. But, usage over time trumps snarky purists like myself.

Kinda like those of you who don't make the distinction between clips, which load magazines, and magazines, which load weapons... but I've ranted about that before!