The Weight of Protection
Written by Christian Sheehy
The U.S. Army's Tank-Automotive and Armaments Command
and Research Lab are working to bring forward the next generation
of lighter, capable up-armoring solutions.
To address its need for lighter, more robust vehicle platforms, the Department of Defense is considering innovations from flexible ceramics to exploding armor, which are poised to replace heavier traditional steel and other metallic-based armor solutions. These, in some cases, not-so-new alloy and composite forms of built-in armor and add-on kitting tend to carry higher at-acquisition price tags, but, along with shorter application cycles and smaller footprints, offer the potential for substantial cost savings over platform life cycles.
UP-ARMOR EVOLUTION
DoD has traditionally favored heavy metallic materials such as steel and iron in armor production due to proven strength and the added protection that greater weight brings to vehicular platform structural integrity. With an increase in armor came increased overall platform weight. This extra weight gave rise to issues of platform performance and mobility often exacerbated by unpredictable environmental operating conditions. Though proven to be robust, metallic armor materials—aside from pushing the weight limitation envelope—are more likely to fail in part under high pressures imposed particularly by ballistics-related threats.
Out of conflicts such as Bosnia in the 1990s, the U.S. Army Tank-Automotive and Armaments Command (TACOM) began introducing up-armored variants of the HMMWV, including the M1114, M1116 and M1145, for Army and Air Force to include accompanying armor kitting technology. This additional armor packaging increased the weight of the M1114 HMMWV to 2,000 pounds more than its standard HMMWV counterpart, introducing steel-plated doors, underbody plating and bonded, ballisticresistant glass.
With the start of Operation Iraqi Freedom in 2003, the U.S. Marine Corps Expeditionary Force began outfitting its M998 HMMWV platforms with “hard armor” kitting produced by O’Gara-Hess & Eisenhardt, a component of Armor Holdings, now a BAE Systems company. This additional protection included upgrades to window and underbody platform aspects.
By 2004, the U.S. Army began purchasing Level 2 up-armor packages for the more than 2,000 armored HMMWVs and other tactical and combat ground vehicles in Iraq. This next-generation armor kitting included a ballistics-resistant windshield and side and rear armor plating, enabling crew to survive attack from 7.62 mm gunfire and adjacent IED blasts. As added protection against IED and RPG attacks, the service, in coordination among engineers at the Army Research Laboratory, produced a modified armor survivability kit (ASK), which included armored doors, ballistic-resistant windows and seatback protection.
Prior to the advent of MRAP in 2004 and other v-shaped hull designs, the Army implemented a stop gap, Level 3 up-armoring solution that added steel plating to the top and bottom of HMMWV and various other combat and tactical vehicle platforms. Though providing greater protection from IED and RPG attacks, a major drawback was the added weight of anywhere from 1,000 to 4,000 pounds to each vehicle, putting added stress on engine, suspension and transmission equipment.
LTAS
The Army has been moving its tactical vehicle fleet toward the Long Term Armor Strategy (LTAS). This strategy incorporates an A-cab/B-kit configuration. A-cab means the crew compartment is structurally ready to accept armor. Mounting provisions are incorporated into the production design, making installation of armor easier and quicker. B-kit refers to the armor kit that is placed on the A-cab. The strategy allows for the B-kit solution to be configured to specific user requirements and adaptable to potentially take advantage of high technology solutions, which include higher performance or lighter weight, depending on the requirement.
The Army’s Tank-Automotive and Armaments Command project manager, tactical vehicles, is currently fielding several upgrades to the up-armored HMMWV fleet in support of overseas contingency operations. Upgrades are continuously reviewed against survivability, safety, vehicle performance, human factors and sustainment to ensure proper tradeoffs are made, if required.
The baseline armor strategy was part of the manned ground vehicle program. “As we transition to the ground combat vehicle, armor research and integration by the Army Research Laboratory and the Tank Automotive Research, Design and Engineering Center continues as part of the tech base to support the Army’s future vehicle needs,” said an Army TACOM spokesperson. “We continue to mature composite armor to maximize integrated vehicle survivability while minimizing parasitic weight inherent in the current solutions.”
RETHINKING PROTECTION
With ground vehicle platform protection, aside from particular combat and tactical vehicle platforms such as Stryker and LAV, the talk of using nonmetallic armor composites has only been ongoing for the last few years due to cost-per-unit budgetary constraints. Recent developments in survivability have focused on lightweight ceramic armor solutions for helicopters, body armor and vehicle solutions. BAE Systems, Hamilton, Ohio, currently offers ceramic composite solutions such as silicon carbide, aluminum oxide and high-end flouron carbide.
“In the last three to five years, a convergence of survivability type equipment has been occurring in the arenas of ballistics, blast and occupant protection type of capabilities in finding the best system-level solution for particular military missions,” said Don Dutton, vice president, Platform Survivability, Security and Survivability Division, BAE Systems. “That is driving the effort to find the best material solutions in meeting both mission and cost requirements.”
Much of this re-focus on lighter weight, ceramic composite armor alternatives has come from experiences in the field with environment challenges posed by actions in Iraq and Afghanistan. With helicopter platform protection, there is an understood acceptable ratio between protection and allowable weight requiring higher-end materials such as ceramic composite armor solutions.
“As in airlift platforms such as helicopters, designing protective armor that does not restrict airlift capability is as important to the protection of occupants as any outside threat potential,” said Dutton. “Similarly, in ground vehicle platforms, ensuring that armor protection does not affect vehicle mobility in particular terrain environments can be the difference between mission success and failure.”
In airlift scenarios, add-on armor solutions that are configured with the same footprint of base armor systems are also driving DoD acquisition decisions.
“The trick has been finding a way to increase platform performance while not sacrificing vehicle protection in order to achieve decreased weight objectives,” said Dutton.
A part of the ceramic composite armor solution focus is for light and medium tactical ground platforms that have “off road” mission capabilities because they tend to encounter different threats than those often associated with “on road” missions such as IEDs. Taking into account the limit of particular “internal” (engine and drive train) elements of particular platforms as opposed to just “external” (road/ terrain conditions) is becoming a greater part of research into best designing weight-toprotection ratios for certain vehicle systems.
TENSYLON
Traditional metallic solutions are composed of a fiber laminate aspect in many polyethylene solutions. BAE Systems has introduced an antiballistic, polyethylene solution called Tensylon that offers similar performance to other polys, but at lower cost. Typical ceramic composite armor solutions use the ceramic element to “break up” or fracture the threat while the exterior laminate “captures” or absorbs the threat.
Traditional metallic armoring is monolithic in that it does both breaking up and capturing in one. Tensylon has flexural strength, and proprietary composite formulations result in less delamination, which is important in overmatched threat situations. It is ballistically more efficient than typical woven para-aramids used in military ground vehicles.
Offering a reduction in spall quantity and cone angle inside crew compartments, Tensylon ballistic composites can be utilized as a ballistic blanket for military ground vehicles, commercial armored vehicles and aircraft. It is fully qualified for applique armor applications and is an integral component of the leading value candidate for EFP and RPG defeat solutions and meets all specifications for spall liners at similar costs and lower aerial densities than MIL-DTL-62474-compliant composite laminates.
Anti-ballistic composites such as Tensylon are made in application-specific widths to maximize material yield, resulting in a cost savings over armor plating, which is purchased by piece, not exact measurement. Individual protection applications include helmets, hybrid and monolithic insert plates, and body armor.
KIT TRANSITION
In addressing the need for lightweight armor solutions, Ceradyne Armor Solutions engineers work predominantly around a technical ceramics core competency. With currently only a few DoD combat ground platforms, such as Stryker, LAV and ASV, implementing armor composites—the use of advanced technical ceramics in armor solutions—still lacks momentum in the United States, as opposed to among European nations, many of which routinely equip their combat vehicles with ceramic armor solutions.
“In the U.S., we have a tendency to lean toward heavy metallic armor solutions that have been proven effective, but bring added weight that is only desirable to a point,” said Marc King, president, Ceradyne Armor Solutions Inc. “The general rule in armoring is that if it weighs less, then it costs more. Along with the issue of traditional favoring, the cost difference in metallic versus ceramic is an initial higher investment despite the potential that ceramic composite materials can offer savings identified over longer life cycles.”
Early in Operation Iraqi Freedom, armor A-kits used by special operations teams weighed about 900 pounds for use with a 2,000-pound ground vehicle platform, such as a HMMWV. Aside from this armor kitting, the Army was fitting standard HMMWVs with an additional 2,300 pounds of steel armor solution. This potential 3,200 pounds of added weight to an initially 2,000-pound frame excluded any mass from troops and equipment.
Lighter weight metallic and ceramic composite solutions often carry a 20–30 percent increased cost over traditional heavy metallic armor solutions. With the higher acquisition price tag comes a weight savings for each vehicle of as much as 40 percent of rated carrying capacity when compared to metal solutions. “The cost savings in additional payload capacity and life cycle weight-driven wear and tear is something to be considered,” said King. “Higher cost at acquisition can equal lower cost over platform life cycle; however, the division in funding between acquisition and life cycle rules out the smarter investment.”
In recent years, U.S. special operations teams in Iraq have made a greater investment in a lighter weight ceramic composite armor solution because of terrain challenges that did not allow for easy wrecker vehicle access in event of breakdowns,” said King. “They implemented use of vehicle platforms with special lightweight side and rear panels and underbelly protection armor protection systems integrated into replacement seats.”
The Army’s current B-kit is an all-aluminum armor solution. Ceradyne’s ceramic composite solution has gone through initial round shaker table and crew cab testing, and is in a second round with a weight reduction over the current Army B-kit by 40 percent. “When talking about a medium-sized truck cab with all the square footage, 40 percent is a big weight savings,” noted King.
LINE-INSTALLED ARMOR
To meet the need for increasing numbers of armored HMMWVs, AM General responded with production line-installed armor for the M1100 series HMMWV beginning in 2005. This includes underbody and perimeter ballistic protection.
“The robust design and many improvements to the HMMWV make it well-suited as a base platform for special forces use,” said Michael S. Hopkins, director, Congressional affairs, AM General, Arlington, Va. “This is reflected in the U.S. Special Operations Command designation of these specialized HMMWVs as ground mobility vehicles [GMVs].” Most of these GMVs destined for U.S. special operations forces now come off the production line as M1165 models, complete with A- and B-kit armor that provides mine and ballistic protection. This armor can be augmented or removed, depending on mission requirements and the relative priorities for performance, including speed, off-road mobility, payload and protection.
JLTV
AM General is incorporating armor protection and is responding to battlefield conditions with the development of the joint light tactical vehicle (JLTV) for U.S. and allied military forces. Partnered with General Dynamics Land Systems in the general tactical vehicles joint venture, GTV received one of three technological development contracts awarded by DoD in October to develop the JLTV.
Tentatively slated for production in 2012–2015, the JLTV will provide increased protection, performance and payload with the operational advantages of transportability and all-terrain mobility for which the HMMWV is famous. GTV’s innovative design for JLTV features a robust lightweight hybrid hull, modular armor, semi-active suspension system, digital cockpit, and over 95 percent common components across the entire family of vehicles. ♦