Posted 06/13/05 09:02
Naval Gatling Gun Given Anti-Mortar Role
U.S. Army Eyes Defense Against Iraq Insurgents
By GREG GRANT
The U.S. Army hopes it has found the answer to Iraqi insurgents'
lethal mortar and rocket attacks in its Counter-Rocket Artillery
Mortar system (C-RAM), designed to shred incoming projectiles in a
curtain of lead fired from a huge Gatling gun.
When its radar picks up an incoming round, the C-RAM can set off
strobe lights to alert people to take cover, unleash a blast of 20mm
shells and dispatch an armed unmanned aerial vehicle (UAV) to kill
whoever fired it.
The C-RAM is built around the Raytheon Phalanx Close-In Weapons System
(CIWS), a radar-guided, multibarrel gun used on U.S. Navy warships to
shoot down incoming missiles.
The system networks a ground-based version of Phalanx with the Army's
Lightweight Counter Mortar Radar and Q-36 Target Acquisition Radar,
which detect incoming rounds and pinpoint their origin. Even before
the projectile lands, the system can feed the firing location to a
Hunter UAV armed with Viper Strike laser- designated munitions.
The first two C-RAM systems arrived in Iraq in mid-May, the product of
an early 2004 demand from Army Gen. Peter Schoomaker. The service
chief of staff demanded some means of protecting U.S. troops on the
sprawling American bases that dot Iraq. These bases have become a
daily target of insurgent mortar and rocket strikes.
Green Zone Ground Zero
The Green Zone in downtown Baghdad, seat of the newly installed Iraqi
government as well as the U.S. embassy and other government and
military installations, is another favorite target of Iraqi indirect
fire attacks. Despite nearly constant U.S. aerial and ground
surveillance of suspected firing points, mortar and rocket attacks
into the Green Zone spike whenever the Iraqi parliament gathers or
news of visiting dignitaries reaches the insurgents.
The indirect fire attacks are not particularly accurate, according to
military intelligence sources in Iraq, but the insurgents know that
any explosive lobbed into the base, crammed with troops and civilian
personnel, is likely to inflict casualties.
C-RAM uses the Phalanx Block 1B system, which uses a forward-looking
infrared sensor to track incoming objects even very small ones and
its outgoing shells. Tests since its fielding in 1977 have shown
Phalanx to be effective in shooting down high-speed maneuverable
missiles, unguided rockets and even 155mm heavy artillery rounds.
But a city presents a tougher challenge for radar engineers than the
open ocean, where there are no buildings to clutter the sensor
picture. Raytheon modified the radar system's software package, but
left the Phalanx basically unchanged.
The C-RAM's Phalanxes are loaded with different rounds than the 20mm
depleted-uranium slugs used aboard warships. Army officials decided
that the slugs, fired at a rate of up to 4,500 a minute, were not
appropriate for use in densely populated cities.
So officials went looking for a round that would blow up in midair,
before it could cause accidental death or damage on the street. The
answer was provided by the 1960s-era Vulcan program, an air-defense
system designed to operate directly behind friendly ground forces. The
Vulcan used a 20mm high-explosive round that explodes in midair.
The rounds work not so much like "punching metal, but more like
raining metal," said Col. Rickey Smith of the Army's Futures Center,
which developed and fielded the C-RAM. "It's more like BBs blowing out
there that rip through and shred" the incoming projectiles.
Smith said one of the greatest benefits of C-RAM is its early warning
of indirect fire attack.
When it detects incoming rounds, strobe lights go off and "incoming"
flashes on computer screens, giving people nearby the vital seconds to
get down flat on the ground or to duck into bunkers. He said such
measures have been shown to reduce casualties by 65 percent.
A prototype of the modified Phalanx was tested in December at Yuma
Proving Ground, Ariz., against 60mm and 81mm mortar rounds. Sources
familiar with the tests said the CIWS shot down 78 percent of incoming
projectiles.
In later tests of the system's ability to send targeting data to the
Hunter UAV, the Viper Strike munitions hit all identifiable targets.
Fast Work
Gen. John Abizaid, head of U.S. Central Command, saw early tests and
was immediately enthusiastic.
Schoomaker launched the effort in a hurry, going outside the
Pentagon's standard acquisition process to ask the Army Futures Center
to fast track a counter to the insurgents' mortar and rocket attacks.
Smith said they were able to field the first systems barely eleven and
a half months after the original request because of the center's
ability to rapidly integrate off-the-shelf systems and facilitate
their fielding. He said it's a new approach to getting vital
capabilities out to soldiers during wartime.
The Army received two CIWS systems via a March 3 Navy contract with
Raytheon. C-RAM was funded in the 2005 supplemental at $75 million,
with an additional $183 million allocated in the House version of the
2006 Defense Bill.
Smith said additional acquisitions of the system are expected as
coverage is extended to U.S. bases throughout Iraq and, ultimately, to
high-value Iraqi government facilities.