Wired News August 22, 2002
U.S. Military Uses the Force
By Noah Shachtman
One of the most dangerous and pervasive threats facing American and British troops in combat zones is a primitive grenade launcher that only sets your typical terrorist back about $10.
The Anglo-American defense against this no-tech threat: an electrical force field that's costing hundreds of millions of dollars to develop.
Fitted on light armored vehicles such as personnel carriers, the force field uses a series of charged metal plates to dissipate the effects of rocket-propelled grenades (RPGs), a weapon found by the thousands from Mogadishu to Kabul to Baghdad.
RPGs and other "shape charge" munitions derive their destructive power from cones of copper embedded in their noses. When the warhead explodes, it crushes the cone, shooting out a jet of hot copper at 5,000 mph -- instantly destroying anything short of a tank.
The electrical armor system, powered by the vehicle's regular supply of electricity, stops the jets by zapping them with tens of thousands of amps of current. This vaporizes some of the deadly copper jets and reduces the rest to a relatively harmless mixture of melted and pulverized debris that disperses around the vehicle.
In recent proof-of-concept tests by the British military, RPG attacks on an electric-armor-equipped personnel carrier left only dents and scratches.
"We knew that just a few amps blows a household fuse. So we scaled it all up to fry these copper jets," said John Brown, the physicist at the Defense Science and Technology Laboratory who heads up British electric armor research.
Brown has been working on developing the system for six years. He expects it will be ready for widespread deployment in "certainly 10 years, and maybe quite a lot less than that."
But the menace facing soldiers in personnel carriers is here now.
In use since the early 1960s, and weighing a little more than 15 pounds each, RPGs can total a carrier from nearly 1,000 meters away. They are cheap and extremely easy to get.
"RPGs can be easily picked up from street stalls for as little as $10 in most of the world's trouble spots," Brown said.
"RPGs are extraordinarily widespread," said John Pike, director of GlobalSecurity.org. "And if you have any doubt of that, watch Black Hawk Down."
Tanks are largely protected from the threat of RPGs, Pike said, because they use "reactive armor": bricks of explosives that detonate the grenade before it hits the tank's skin.
But such armor weighs 10 to 20 tons, too much for trucks and personnel carriers to bear. These vehicles must be light to function in the mobile, often urban, combat that military planners predict will become common.
Electric armor only weighs a ton or two, and offers much of the same protection as the reactive defense. That's why the U.S. military plans to spend more than $74 million on electromagnetic armor and gun research and development in the next fiscal year. It spent more than $110 million on the endeavor over the last two years.
"When Americans get to the west side of Baghdad and find they've got to fight street to street to get to the east side, this (electric armor) is the kind of thing they'd like to have," Pike said.
Against enemy tanks, however, electric defenses won't do much good. And "any armored warfare guy would tell you that the biggest threat to light armored vehicles are heavy armored vehicles" like tanks, said Clark Murdock, a senior fellow at the Center for Strategic and International Studies, in an e-mail interview.
Shells from tanks rely on solid pointed chunks of tungsten or depleted uranium to break through armor, instead of the copper jets RPGs use.
Also, the electric armor can't protect carriers from mines and bombs dropped from the sky.
"This is a very specific solution to a very specific problem. It's definitely not like the force screens you'd see in the movies," Pike said.
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