The United States military’s involvement in counterinsurgency operations in Afghanistan and Iraq means that American forces are often operating at close quarters with the enemy, often in urban environments. This state of affairs had left tactical vehicles vulnerable to attack by rocket-propelled grenades (RPGs) and other rocketpropelled, armor-penetrating weapons.
The U.S. armed forces and their industry partners
face a number of dilemmas in devising defenses to these weapons. Chief among
these is to devise a product that is non-lethal, so as to minimize collateral
damage as well as potential fratricide.
The armed services, as well as private industry
concerns, both in the U.S. and overseas, have devised and continue to develop
defenses that protect vehicles from the worst of an RPG or similar attack. These
defensive systems can be broadly divided into two categories. Passive defenses,
such as netting or bar armor, equip a vehicle with material designed to absorb
the force and blunt the trauma associated with an RPG hit. Active defenses are
those mounted on vehicles that detect, classify and track incoming threats
before launching a countermeasure which either blocks or diverts an RPG, or
disables it in such a way as to prevent it from penetrating the vehicle’s
armor.
The Defense Advanced Research Projects Agency
(DARPA) began working on a vehicle protection system five years ago, in response
to developments in the war in Iraq. “Our program was designed around protecting
light tactical vehicles,” said Karen Wood, a program manager in DARPA’s
strategic technology office. “That is where we were suffering the heaviest
damage in Iraq—from bullets, RPGs, direct-fired mortars and anti-tank guided
missiles, and we wanted to see what we could do to help with their
survivability.”
The DARPA program, dubbed Crosshairs, contains a
number of components, including an active protection system. DARPA tested a
number of passive protection systems before deciding to integrate the active
system, known as Iron Curtain.
The Office of Naval Research is also sponsoring
science and technology research and development on vehicle protection systems
for eventual transition to the Navy and Marine Corps. “Within the confines of
what we can do against RPGs, we have invested in non-lethal approaches to
protect Marines in the field and naval forces,” said Rodney Peterson, an ONR
program manager. “The fact that Marines and troops are outside of their vehicles
much of the time means we need to have a non-lethal protection mechanism to
incapacitate an incoming threat without endangering troops outside the
vehicle.”
One example of a passive defense for tactical
vehicles was developed in the United Kingdom by AmSafe. Known as Tarian, the
Welsh word for shield, AmSafe’s is a textile-based system specifically designed
to defeat RPGs. The company began development of Tarian in 2005 in conjunction
with a U.K. Ministry of Defence laboratory. Testing took place last
year.
“The product is based on the application of
lightweight textiles to provide armor,” said Neal McKeever, the company’s
director and general manager for defense. “Tarian can replace traditional steel
or aluminum bars or slat armor. We are unable to disclose details of how Tarian
works because of a secrecy order we have with the MOD, but it does work in a
similar fashion to steel or aluminum.”
Textile-based solutions such as Tarian, as well as
steel and aluminum bar protection, are mounted away from a vehicle’s surface so
that the tip of a flying RPG warhead hits the outer protective layer first. This
triggers the RPG to form its plasma jet prematurely, dissipating much of its
focus and energy by the time the weapon strikes the vehicle’s armor plate, and
lacking the force to pierce it.
The key advantage that Tarian offers over its
metallic cohorts is a 50 percent weight savings off aluminum and 85 percent off
steel bar armor. “One of the specific opportunities that the British army sees
with the weight savings is that more equipment, ammunition and supplies can be
added to the vehicle,” said McKeever.
Tarian is being evaluated on the U.K.’s heavy
equipment transport (HET) vehicle and on the Spartan armored reconnaissance
vehicle. In the U.S., DARPA is also testing Tarian. McKeever believes that once
Tarian passes its tests on the HET, “there will be keen interest to transition
the product to other vehicle types.”
Active RPG protection systems include the ASPRO
(armored shield protection) system, also known as Trophy, marketed by Israel’s
Rafael Advanced Defense Systems. The systems are designed to enhance the
survivability of tracked and wheeled armored tactical vehicles against a variety
of battlefield threats.
Trophy defeats incoming threats with three phases
of operation: threat detection, threat tracking, and finally, activation of the
hard-kill mechanism that neutralizes the threat using a countermeasure before it
impacts the vehicle.
The threat detection and warning subsystem consists
of several sensors, including search radar with four flat-panel antennas,
located around the protected vehicle. The neutralization process takes place
only if the threat is about to hit the platform.
Trophy has already been retrofitted on some of the
Israel Defense Force’s existing Merkava Mk 4s. All Merkavas now coming off
production lines are being outfitted with Trophy, according to Didi Ben-Yoash,
Rafael’s business development manager.
“The system detects, tracks and classifies threats
by radar,” explained Ben- Yoash, “and then destroys the threat with a
countermeasure. Trophy protects against a wide range of threats, including all
known anti-tank rockets and anti-tank missiles. The system provides full
performance against shortrange threats, in close and urban terrain, and under
all weather conditions. It can engage several threats from each direction
arriving simultaneously.”
The countermeasure is based on a technology known
as multiple explosive form penetrators (MEFP). “MEFP is a way to create a very
fast hit directly at the incoming threat,” said Ben-Yoash. MEFP technology was
developed in the 1980s to provide a warhead that could produce many penetrators
to attack light materiel targets.
It took Rafael around 15 years to develop Trophy,
said Ben-Yoash. The system was declared operational in August 2009. Published
reports have indicated that Rafael has exported Trophy to several military
organizations in countries outside of Israel, but Ben-Yoash was unwilling to
comment on any international sales.
The DARPA Iron Curtain is being developed by Artis
LLC, a McLean, Va.,-based company under contract to DARPA. Iron Curtain consists
of four major component groups.
“When a tactical vehicle is rolling down the road,
the system is not in an armed state for safety reasons,” explained Keith
Brendley, the president of Artis. “An incoming RPG will be detected by a C-band
radar system, which then communicates the threat to a fire control system which
then decides whether to put system into an armed state.”
Once Iron Curtain switches to an armed state, the
sensing is handed off to a series of optical sensors that are distributed around
the vehicle. “The optical sensor looks at the threat in detail, and an automatic
target recognition system associated with the optical sensor determines what the
incoming threat is, right down to the type of RPG,” said Brendley. “The optical
sensor profiles and classifies the threat to select the proper aim point and
determine which countermeasure to fire.”
Once the system determines that the RPG is on
course to hit the vehicle, a countermunition mounted on a vehicle roof rack is
activated. “The counter-munition acts straight down so that there is no
collateral damage,” said Brendley. “One of the big features of the system is its
accuracy. We are able to hit precisely the part of the threat we are aiming
at.”
When the RPG is within inches of the protected
vehicle, the countermeasure is deployed, disabling the weapon without detonating
it and causing the disabled RPG to bounce off the vehicle side. It may cause
some damage to the vehicle, Brendley noted, but it will not be able to penetrate
the vehicle armor. “You still need some armor, but not much,” he
said.
Iron Curtain currently defeats all known RPG
threats and is moving toward the ability to defeat more challenging threats such
as anti-tank guided missiles. “Iron Curtain’s ability to profile and classify
targets enables it to efficiently address new and emerging threats, usually with
nothing more than a software change,” said Brendley. “This flexibility prevents
Iron Curtain from becoming obsolete.”
Iron Curtain is part of a larger DARPA vehicle
protection program called Crosshairs, which was devised to develop a number of
capabilities. First, is a detection tracking and shooter localization
capability. The next is a capability that facilitates a response decision. The
third capability involves controls and displays to designate targets and improve
situational awareness.
“The fourth capability is networking,” said Wood.
“We use EPLRS [enhanced position location reporting system] compatible radios to
network to surrounding vehicles so that they are aware of the shooter and the
threat. The fifth capability is an active protection system. Out of that effort
finally came Iron Curtain.”
Before deciding on Iron Curtain, DARPA considered
other alternatives for Crosshairs, including passive defense systems such as
metal mesh anti-RPG netting and bar armor. “We developed the sensor system and
other capabilities in parallel,” said Wood. “We are now in the process of taking
the first four Crosshairs capabilities and are integrating the survivability
piece, which turns out to be Iron Curtain.”
DARPA is currently in the final phase of preparing
the system for testing on HMMWVs and mine resistant ambush protected (MRAP)
vehicles. “We expect that the MRAP program office will look at Crosshairs as a
potential counter-RPG solution,” said Wood. “There is currently an urgent needs
statement for a counter-RPG system in Afghanistan that this can
address.”
Once testing is done, Brendley believes that Iron
Curtain can be fielded fairly rapidly. “We anticipate being designated as a UMR
[urgent material release],” he said. “That is the assumption that DARPA has
instructed us to work under.” Brendley anticipates an initial deployment of
several dozen systems, “followed by a much larger number.”
The Office of Naval Research has demonstrated a
system called Shotscreen, developed by Mechanical Solutions Inc. of Whippany,
N.J. Shotscreen, like Crosshairs and Iron Curtain, uses sensors to detect an
incoming threat and a countermeasure to defeat it. One difference between Iron
Curtain and Shotscreen is that Shotscreen defeats the threat at a 20 to 30 feet
standoff from the protected vehicle.
Peterson said ONR has been collaborating with DARPA
and the U.S. Army on this project and noted that it may be appropriate to
develop more than one anti-RPG active protection system. “There may be a number
of different paths to defeating an RPG or a threat of similar magnitude,” he
said. “Different kinds of packages may be heavier or lighter, more or less
complex, or may involve mechanisms that users may prefer or not
prefer.”
Shotscreen started as a Small Business Innovation
Research (SBIR) project in 2009 and is currently at the end of the first year of
a two-year commercialization phase. “Within one year we believe we will be
acquiring a prototype of the system and conducting a demonstration for the
Marine Corps,” said Peterson.
After that, it will be up to program managers in
the Army and Marine Corps to decide whether they wish to proceed with
procurement and acquisition activities with Shotscreen. “At that point, there
may be further research and development to adapt Shotscreen to specific systems
before it is eventually acquired and fielded by one or more of the armed
services,” said Peterson.
An active RPG defense that combines the attributes
of a live countermeasure and a barrier defense is being developed by Control
Products Inc., an engineering company based in East Hanover, N.J. The company is
working on an RPG barrier that is launched from the vehicle to intercept a
threat several yards from the vehicle.
”We have developed a fairly robust barrier in the
shape of a parachute that is towed by a single solid fuel rocket and which
achieves the objective of creating a barrier away from the host vehicle,” said
CPI’s Rich Glasson. This minimizes the threat of fratricide, he noted. CPI’s
system does not include a threat detection component. “Our system is the
responding component,” said Glasson. “We receive the threat vector and launch
the countermeasure.”
Once the countermeasure is launched, the
parachute-like barrier is unfurled, and it is that device which deflects the RPG
off of its original course.
Glasson contended that actually catching and
stopping an RPG is exceedingly difficult because of the velocity and mass of the
weapon. But testing on CPI’s barrier system, which includes a counter-munition
similar to that of an RPG, has shown that it is possible to mitigate the effects
of an RPG attack by disrupting the weapon’s flight path, by defusing the
munition and causing it to blow itself up, or to deform the weapon and prevent
it from forming the plasma jet necessary to penetrate steel armor when it
explodes.
“Our barrier seeks to deflect, deform and defuse
the RPG before striking its intended target, and not to catch and stop it,” said
Glasson. “One of the advantages of our system is that it covers a wider area.
We’re not trying to hit a bullet with a bullet, and we don’t have to precisely
strike a fast moving target. We just have to put the barrier out there.”