America hasn't agreed to the new international agreement on cluster bombs. But there is new pressure to find alternatives to the munitions. And that's led to a US Army warhead which saturates the target area with thousands of lethal darts.
The Army's Multiple Launch Rocket System (pictured above) has a particularly serious problem when it comes to leaving dangerous duds. The standard missile contains 644 M77 grenades; a single salvo will involve three vehicles each firing their complement of twelve rockets – that's 23,184 grenades in the target area. The aim is a dud rate of two percent. But even at one percent, that's 200 potentially lethal bombs left scattered over a wide area, posing a threat to friendly troops and civilians. The missile cannot be used in Afghanistan or Iraq for this reason.
This is why the Army have developed an alternative warhead. It is based on the GPS-guided version of the MLRS rocket, so it is far more accurate than the earlier rockets. The warhead consists of thousands of small darts, or flechettes. (The Army calls them "kinetic energy rods.") Flechettes, from the French for "little arrow" go way back; aircraft used to drop them in World War I, though not with much effect.
As with the mine-busting darts I looked at last year, the key to its effectiveness is dispensing the payload evenly over a wide area. This involves a clever packing technique and a spinning warhead which breaks open at high altitude so that the darts are well distributed at the time of impact.
The result can be seen in the picture, above. The orange flags mark the impact of each flechette. Like the famous penny dropped from the top of the Empire State Building, the finned rods do damage purely by kinetic energy -- and they are heavier, more aerodynamic, sharper and come down from a much greater height.
It's a similar concept to the Air Force's CBU-107 Passive Attack Weapon. This contains over three thousand darts of three different sizes (that largest weigh a pound and a half), producing what is described as a
"hurricane of metal" within a target area two hundred feet across.
Two PAWs were used during the early days of the Iraq war on antennae on the Iraqi Ministry Of Information, putting the antennae out of action without damaging the buildings. The Air Force has also indicated the PAW is effective against power substations, and will penetrate light roofs used in warehouses and similar constructions.
Such a warhead might not be very effective against targets such as light vehicles (though it would leave parked aircraft with a lot of punctures). It could be made much more effective by replacing the metal rods with flechettes made of Reactive Material which would explode on impact but, unlike cluster bombs, would not leave hazardous duds.
It's been suggested that US Forces will not use cluster weapons when working with troops from nations that have signed the new treaty.
Development of alternatives, both in the US and elsewhere, is likely to be rapid.
[Photo: US Army, Globalsecurity.org]
