Miniature Bomb, Heavyweight Punch

You hear a lot of big claims in this industry. So when I read about a 31-inch, 64-pound weapon that's supposed to have more killing power than a 1,000-pound cluster bomb, I was more than a little skeptical.

After all, a typical cluster bomb distributes over two hundred BLU-97 bomblets over a wide area. Together they produce thirty times as many shrapnel fragments as the 64-pound mini-munition, Textron Systems' Clean Lightweight Area Weapon. It was hard to see how CLAW could compete.

But it turns out that CLAW can be awfully deadly, in its own right. After ejection, CLAW descends by parachute, and a proximity sensor detonates it sixteen feet above the ground. That means its fragments get dispersed far and wide. In contrast, the BLU-97 only goes off on contact with the ground, which sends a lot of fragments into the dirt – instead of into targets. (Check out this video to see what CLAW does to a 16 by 12 foot target.)

The design of the warhead casing helps, too. It's a steel cylinder scored on the inside, so that it forms diamond or arrowhead shaped fragments, over two thousand of them. A special proprietary technique is used to cut the pattern on the warhead casing, creating fragments which are bullet-sized (about 7 grams/114 grains) and effective over a very wide radius. BLU-97 fragments are much smaller (about 30 grains) and less effective.

The explosive filling of CLAW is PAX-21, which is both more powerful and more stable than previous explosives. The combination of explosion and fragments produces thorough coverage of a circular area over 140 yards across, effective against targets including personnel, soft vehicles, parked aircraft and anti-aircraft sites. Textron Systems have precisely quantified this performance with ground tests, and their claim about its effectiveness looks like a strong one.

CLAW’s small size means that strike aircraft could carry it in large numbers, but at present it’s being marketed as the ideal weapon for killer drones. Even something as large as a Predator drone can only carry two Hellfire missiles. For the same weight you could carry several CLAWs, but it also means that even smaller UAVs could be armed for the first time. The development of this type of miniature munition – and even smaller weapons are in the pipeline – brings the possibility of large numbers of armed UAVs on the battlefield for the first time.

(CLAW is not effective against heavy armor, but the same GPS-guided Universal Aerial Delivery Dispenser which delivers it can also be loaded with a BLU-108 anti-tank weapon with four target-seeking warheads.)

But perhaps the most impressive thing about CLAW is how much work has gone into making sure it only explodes when it’s meant to. There is a triple-redundant fuzing system – the proximity fuze, a ground contact fuze, and a time delay. If all of these fail, then the battery dissipates within seconds and the munition is inert. It’s not just unexploded, but unexplodable.

You could hit the CLAW with a hammer, run over it with a tractor or put it in a fire, and it will not detonate. You could take it apart without any personal risk. The insensitive explosive really is insensitive.

“The only way you could make it explode would be to take it to a laboratory,” says Richard D. Sterchele, Textron’s Business Development Manager for Smart Weapons.

This means that unexploded CLAWs cannot be turned into IEDs. Iraq is awash with weaponry, but in other conflicts like Vietnam guerrillas have used unexploded bombs as a major source of explosives.

More importantly, it does not leave hazardous unexploded bomblets scattered around. The failure rate of BLU-97 is widely quoted at around 6%, so each CBU-103 leaves about a dozen potentially lethal bomblets to be cleared up. It is hard to over-emphasize just how dangerous these are; according to the USMC’s Multi-Service Procedures for Operations in UXO Environment:

“Army Materiel Systems Analysis Activity Studies show 40 percent of the duds on the ground are hazardous and for each encounter with an unexploded submunition there is a 13 percent probability of detonation…Thus, even though an unexploded submunition is run over, kicked, stepped on, or otherwise disturbed, and did not detonate, it is not safe. Handling the unexploded submunition may eventually result in arming and subsequent detonation.”

In one incident in 1991, seven members of the 27th Engineer Battalion were killed during operations to clear a runway at As Salam when a pile of ‘dud’ BLU-97’s exploded.

In the Cold War scenario, where the enemy was an invading Soviet horde, unexploded bomblets may not have been seen as a problem. But in scenarios like Iraq and Afghanistan where US engineers are likely to have to deal with them, the argument for a ‘clean’ weapon like CLAW is a compelling one.

It remains to be seen whether the Pentagon will take up CLAW, which is a private company initiative. Live CLAW munition tests from operational UAVs are being conducted by the U.S. Air Force and Army over the summer 2006. It’s a fraction of the cost of a cluster bombs, but the saving in lives could be much more important. But in the world of defense procurement, unfortunately it’s not always that simple.

-- David Hambling

Latest Comments

» View All 6 Comments

» Post a Comment