Lifesaving Shields
Written by Peter Buxbaum
GCT 2011 Volume: 2 Issue: 2 (May/June)
The United States military’s tactical vehicles are subject to a number of vulnerabilities as they operate, often in close quarters to adversaries, in the Afghanistan theater. These include ballistic threats from machine gun fire as well as attack by rocket-propelled grenades and other rocket-propelled, armor-piercing weapons.
There are a number of systems that are available to protect vehicles and their occupants from these threats. These can be divided into three categories.
- Reactive systems endeavor to mitigate the effects of an armor-penetrating munition once it has come in contact with the exterior of the vehicle. This is done by setting off a low-level charge which diverts the shaped charge from impacting the interior.
- Active defenses are mounted on vehicles and detect, classify and track incoming threats before launching a countermeasure that either blocks or diverts an RPG, or disables it in such a way as to prevent it from penetrating the vehicle’s armor.
- Passive defenses—which include various forms of armor from steel to fabric to composites—enable a vehicle to absorb the force and blunt the trauma associated with an RPG hit. Research into fabric and composite materials endeavors to make these ever thinner, lighter and less expensive.
The problem faced by decision-makers when it comes to protecting vehicles and mounted warfighters is that none of these systems present a comprehensive protection solution. Armor alone will not protect against a shaped charge, for example. A sophisticated radar-triggered countermeasure would be ineffectual against machine-gun fire. Armor can be effective against many ballistic threats, but its weight can compromise performance of the vehicle.
What is needed to comprehensively protect a vehicle and its occupants from a multitude of threats is a holistic system that incorporates all three types of defenses, according to Joe Yodzis, senior director for business development at General Dynamics Armament and Technical Products (GDATP). “Ideally you would want to address all the threats out there and do it at a minimum weight penalty,” he said. “To accomplish that you would need a hybrid system with a certain level of passive armor to protect against machine-gun fire, an active system against higher end threats like anti-tank guided missiles, and explosive reactive armor to defeat shaped charges.”
Explosive reactive armor was originally designed to defeat high explosive armor-piercing warheads, the sort found on anti-tank rockets and missiles. Reactive armor defeats these shaped charges by igniting a counter-explosion once the munition has made contact with the vehicle armor. The warhead’s penetrator jet punches through the thin outer layer of the armor and detonates an explosive block behind it. This counter-explosion propels the remnant of the front metal sheet cover out and up, taking the back end of the penetrator jet with it.
The reactive protection uses an insensitive explosive that is detonated only when hit by a missile or rocket. It will not react to other heat sources, or lesser impacts from small arms or shell fragments.
“We have been putting reactive armor on Bradley fighting vehicles for over 15 years,” Yodzis said. “We have put some on Abrams tanks in the last several years. More recently we have supplied the Stryker, which is a lighter vehicle and takes a different kind of reactive armor, but it essentially protects it against the same classes of threats.”
Heavier vehicles such as the Bradley and the Abrams are able to carry heavier reactive armor loads. They can be equipped with more sophisticated reactive armor that protects the lower portions and undercarriage of the vehicle against roadside threats.
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 4 main battle tanks. 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,” Ben-Yoash explained, “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 (MEFPs). “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 15 years to develop Trophy, said Ben-Yoash. The system was declared operational in August 2009.
GDATP expects to introduce an active protection system later this year, according to Yodzis. “The system will include radar for detection of the incoming threat,” he explained, “as well as hard kill and soft kill elements.” The hard kill capability physically destroys the incoming weapon. The soft kill deflects the munition by interfering with its targeting system, Yodzis explained.
GDATP is also working on new approaches to passive armor, with the emphasis on incorporating lighter and stronger materials to replace the legacy varieties. “Traditionally the United States military has used monolithic forms of armor, such as steel or aluminum, and not composites,” said Yodzis.
GDATP is working with a company, 3Tex, based in Cary, N.C., to develop newer forms of passive armor that can be used to protect various classes of combat and tactical wheeled vehicles.
“3Tex has a licensing agreement with General Dynamics,” said Jeremy Akers, director of business development at Kairos Partners Inc., a company based in Chester, Va., which performs project management services for 3Tex. “Right now they are in the process of developing passive armor solutions using 3Tex weave technology.”
3Tex’s fabrics are used as part of composite materials that are sandwiched together in an effort to make harder, lighter armor materials. Most fabrics are comprised of one type of fiber and woven on two axes. 3Tex introduces a third axis to the weave by incorporating additional materials into the base material, typically Kevlar.
Kevlar is a high-strength synthetic fiber developed by DuPont. 3Tex might mix the Kevlar with carbon, specialized glass materials, or Dyneema, an ultra-strong polyethylene fiber developed and manufactured in the Netherlands.
“The third axis allows us to hybridize the material to gain some benefits,” said Akers. “It provides greater strength and ballistic resistance without much increase in the thickness, weight and cost of the material. The idea is to enhance performance without being too expensive and too heavy.”
Different materials are being developed to protect different types of vehicles, Akers noted. “Each vehicle has its own set of threats, so each needs its own solution,” he said.
3Tex’s work has been sponsored in part through research and development contracts with the U.S. Army Tank Automotive Research, Development and Engineering Center. Akers believes that this provides an opportunity for composite materials to be incorporated from the beginning in the newer generation of vehicles, such as the ground combat vehicle and the joint light tactical vehicle, that are now being developed, instead of being added after the fact.
“This has been a hard market to penetrate because the military is married to metallic types of armor,” said Akers. “But we have seen from the up-armoring of Humvees, heavy armor [can] overburden the vehicle design. Lighter forms of armor can prevent vehicles from being overburdened and increase their life expectancy.”
3Tex has submitted its ideas to a vehicle armor challenge sponsored by the Defense Advanced Research Projects Agency (DARPA), which is seeking to identify new armor concepts for military vehicles. The armor challenge is aimed at small organizations that can’t afford full-scale armor development programs. Participants selected by DARPA will be sending samples for testing at an independent facility. DARPA won’t be paying for the research and development efforts but will fund manufacturing and shipping samples and testing. Samples that demonstrate superior performance or incorporate innovative designs may be considered by DARPA for further development.
Another innovation in vehicle ballistic armor comes from NP Aerospace in Troy, Mich. The idea NP Aerospace has come up with is to incorporate ballistic protection in the structure of the vehicle, eliminating the need to slap on armor later.
“NP Aerospace has a long history of designing and developing structural composites with ceramic materials,” said Don Bray, the company’s business director for armor. “There are many armor systems out there that incorporate ceramics, but they are not structural. We can incorporate armor protection into the cab of the vehicle.”
The company unveiled its technology, known CAMAC Armor Systems, to the U.S. market. CAMAC is based on high-performance, glass fiber-reinforced composites, which are consolidated under pressure. “CAMAC forms a protective shield up to 20 percent lighter than the equivalent steel armor, yet able to defeat a wide range of threats, including fragmentation, high-velocity small arms, grenade attack, mine blasts and burning fluids,” said Bray. “Exhaustive tests have demonstrated that CAMAC not only outperforms all previous lightweight armor systems but also offers many innovative structural advantages. CAMAC is lightweight, repairable, upgradeable and has been battle tested by the British army in Iraq and Afghanistan.”
NP Aerospace’s composite crew enclosure for tactical vehicles is called the R-MED, which is available in two-, four- and six-man configurations. The R-MED boasts high levels of ballistic and blast protection and comes with blast attenuating seats. NP Aerospace is currently working with vehicle manufacturers to incorporate these concepts into their designs.
The company has retrofitted a fleet of Land Rovers for the British army with R-MED capsules, which have been used in Iraq and Afghanistan. Bray believes the same approach could be advantageous with the ongoing HMMWV recapitalization program. R-MED is also adaptable to a variety of vehicle platforms such as the MRAP, GCV, JLTV and others.
NP Aerospace has also developed a concept vehicle called the Phoenix, which is made almost exclusively of structural composites. “We tried to eliminate all metal inside the vehicle,” said Bray. “Shrapnel from the metal cab causes as much damage to soldiers as … bullets.”
The Phoenix is made of structural ballistic composite materials with no metal except for a couple of attachments and bolts. “If you are building a brand-new vehicle from the ground up you can eliminate the chassis under the vehicle and position the capsule so that it is load bearing,” said Bray. “This makes it much more blast resistant and provides greater survivability. The vehicle may be destroyed but the capsule will remain intact.”
Lighter weight will be an important feature of any future armor system. “Weight is a big issue for vehicles in theater,” said Yodzis. “Our customers want us to minimize weight and provide protection through an integrated system to take on a range of threats.”
That means that, ultimately, it takes a hybrid system to comprehensively protect vehicles. “You can’t put too much extra steel on a vehicle,” said Yodzis. “Reactive armor won’t protect against ballistic threats. You always need some type of passive armor. Active protection will take on higher end threats not adequately addressed by the other two. You have to see how much weight a vehicle can carry and what its protection needs are and address it by a correct combination of the three.” ♦