Moving the Military
Written by Peter Buxbaum
GCT 2011 Volume: 2 Issue: 4 (September)
Hybrid electric vehicles have been touted in the civilian automotive market as a solution to promote fuel efficiency and to reduce dangerous emissions and dependence on foreign sources of energy. Could the same hold true for military vehicles?
The United States military, along with its industry partners, are working on—and in some cases have implemented—innovations in drive train component technologies that have included increased reliance on electricity.
While some of these developments are directed at promoting fuel efficiency—an established goal in some military quarters— the main quest for the use of electricity is the same as it has always been for moving heavy equipment under difficult conditions: horsepower.
Some industry players are now proposing electrical drive components for major vehicle programs such as the ground combat vehicle and the joint light tactical vehicle. While the electrical aspect of these proposals comes primarily to achieve performance requirements, experts say that progress in fuel efficiency is also on the horizon.
Some companies are also working on adapting existing engines to accommodate alternative power sources, while developments in axle and suspension technologies are being designed to achieve multiple goals, from overall vehicle efficiency to occupant comfort.
Caterpillar has provided engines for a myriad of military vehicles, including seven mine resistant ambush protected (MRAP) variants, the family of medium tactical vehicles, the Marine Corps medium tactical vehicle replacement program, and logistics vehicle system replacement, ranging from 330 to 600 horsepower. Several Army tactical vehicles, including the palletized load system and the heavy equipment transporter, are being recapitalized with Caterpillar engines, with capacities of 600 horsepower and 700 horsepower respectively. The Army and Marine Corps are also in the process of testing Caterpillar engines in HMMWVs.
The engines provided by Caterpillar to the military “are virtually identical to the engines we supply to the civilian market,” said Jeff Anderson, the company’s engine product division manager. “Our philosophy is to leverage commercial products into as many market niches as we can, including the military.”
This Caterpillar philosophy is based on their perceived manufacturing advantages. “Manufacturing the same engine time after time improves the quality and reliability of the product,” said Anderson. “We also have 188 dealers around the world with 230,000 employees. They are our parts and service arms and they provide support to all the vehicles almost everywhere around the globe.” Caterpillar dealers in Kuwait, Iraq and Afghanistan have supported vehicles deployed by U.S. military forces in Southwest Asia, Anderson added.
A different approach is taken by Steyr Motors GmbH, an engine manufacturing company based in Steyr, Austria. “We design engines for military applications. We do not take commercial engines and militarize them,” said Rudolf Mandorfer, the company’s chief executive officer. “We decided to take this approach many years ago.”
Steyr engines include cylinder heads and blocks that are fashioned in a single unit, which, according to Mandorfer, provides protection against overheating in difficult cooling conditions. Steyr’s injector equipment, which was developed in-house, provides the company’s engines with the capability of running on multiple fuels, including jet fuel and kerosene.
“We avoid the limitations of commercial off-the-shelf products but we still have to be competitive,” said Mandorfer. “We have to balance commercial pressures with developing engines suitable to special applications.” Steyr attempts to achieve this balance by devoting 50 percent of its manpower to engineering. All of its hardware, software, electronic and electric development is done in-house.
The focus of Steyr’s development efforts is to achieve “the highest power output from our in-line six cylinder engine,” said Mandorfer. “We have applied a charging system with low and high pressure turbochargers through which we can achieve a 70 kilowatt per liter displacement. That means 300 horsepower from a six-cylinder engine. As we continue development along these lines we expect to get 100 kilowatt per liter displacement and 400 horsepower from a six-cylinder engine.”
BAE Systems, together with teammates Northrop Grumman and QinetiQ, is developing a hybrid electric drive vehicle, which has been included in the company’s proposal for the Army’s ground combat vehicle. “This system is a scaling of the propulsion systems that were developed under the Future Combat System and much of the same team is involved,” said Mark Signorelli, vice president and general manager for weapons systems at BAE. “We are seeing a natural evolution of the technology. The propulsion system was originally scaled to a 24-ton vehicle, then up to 32 tons, and now it has been scaled to a 70-ton vehicle. The interesting piece is that this technology is almost infinitely scalable. Electric power is very mature and well understood.”
While many associate hybrid drives with fuel efficiency, BAE views the real impetus toward the move to electric drives as the integrated performance requirements of the vehicle. “Torque, sustained speed, and acceleration are the primary requirements,” said Signorelli. “Weight, packaging, reserve power, and electric power generation are some of the secondary requirements, all of which, taken together, indicate hybrid as the best solution.”
Another advantage of the HED electric transmission or traction drive system is the physical decoupling of the engine from the transmission, according to Signorelli. “This has the effect of being able to reduce the size of the overall package,” he said. “You can also get creative on how you package the overall vehicle. We are always trying to optimize vehicle configurations against a set of constraints. Not having the engine directly hooked to the transmission or bolted to the drive shaft eliminates one of the major constraints.”
Besides bidding on the GCV, BAE is also looking for vehicle upgrade programs through which to apply its hybrid drive technology.
Large engines such as L-3 Communications’ AVDS-1790, which powers the Heavy Equipment Recovery Combat Utility Lift & Evacuation System (HERCULES), could benefit from the additional horsepower provided by alternative sources such as permanent magnetic motor technology, if the military decides to invest in that technology.
“My role involves looking at how we can move our core technologies to alternative energies,” said Philip Chizek, marketing and business development manager for L-3 Communications, Advanced Power and Propulsion Systems. “We build large wind turbine generators and other large generator systems and we are trying to move those into other areas such as vehicle technologies.”
Magnetic motors are situated between the engine and the transmission and can potentially provide between 60 and 400 kilowatts of additional power, according to Chizek. “Depending on how the system is configured,” he explained, “this additional power can provide more performance torque to the wheels to help get a vehicle out of mud, or the vehicle can tap into it for extracurricular items such as radar systems.”
L-3 has tested electric drives and electric generator systems on the gamut of military vehicles and is ready to offer those to vehicle manufacturers for incorporation in military platforms. Chizek also sees opportunities in this area for upgrading existing vehicles to boost their horsepower and achieve better fuel economy.
“What we would really like to see is to add this technology to vehicles without having to build a whole new vehicle,” said Chizek. “Integrating electric drives and electric generator systems into existing platforms is a nice upgrade opportunity.”
Caterpillar has introduced innovations in electronically controlled automatic transmissions in recent years, which have had the effect of promoting fuel economy. The company entered the transmission business five years ago and has since provided transmissions to the Buffalo A2 MRAP and the Caiman multi-terrain vehicle.
“We recently introduced a two-speed, shift-on-the-fly transfer case and an electronic control module on the transmission,” said Anderson. “We are able to put 12 gears behind the engine instead of six or seven. That way we can keep the engine running at its more natural sweet spot which tends to be at lower rpms.”
At 60 miles per hour, the electronically controlled transmission means the engine runs at 1,600 rpm instead of 2,200, according to Anderson. “That’s going to reduce fuel consumption,” he said.
Drive train improvements are not limited to power and transmission systems. Innovations in axle, suspension and damping technologies also contribute to vehicle efficiency and occupant comfort.
Lord Corp. provides an advanced active damping system that improves wheel contact with the road surface and applies damping force only as necessary, which improves overall efficiency of the vehicle operation. Lord has invested in active damping systems based on magneto-rheological fluid, explained James Yakel, the company’s business development manager for military ground vehicles.
“This enables a small electrical current to vary the damping force at each wheel shock absorber position in response to the vehicle movement, providing stability control, enhanced ride quality and improved speeds mission effectiveness over terrains encountered by military vehicles,” he added. “Lord active damping systems are designed to be easily programmable on vehicle so future improvements can be accommodated at minimal cost.”
One of the direct results of added weight to existing military vehicles is a reduction in suspension travel, which adversely impacts mobility performance. “Lord active damping systems buy back a significant level of performance lost as a result of added weight, enabling the vehicle to perform as well or better despite the additional weight,” said Yakel. “Lord active damping systems provide enhanced performance, resulting in ability to traverse terrain faster with less exposure to the enemy and improved stability for any evasive maneuvers or a hasty exit.”
Lord Corp.’s active damping system has been applied to the light, medium and heavy class military vehicles, including MRAP, for developmental work, test and application engineering. “The system demonstrated 10,000 miles of durability testing recently at Nevada Automotive Test Center on the medium class 4-by-4 Army truck, with no system failures,” said Yakel. “I expect that future military customers will no longer be content with passive shock absorbers systems and will demand the stability control, enhanced ride quality at all seating positions, and improved mission effectiveness provided by active damping systems.”
Independent suspension systems have become an important upgrade for MRAPs for the sake of the comfort of the occupants. “The U.S. military acquired a lot of MRAPs in a hurry,” said Jay De Veny, engineering manager for military programs at AxleTech International, a division of General Dynamics. “These vehicles originally had solid axles, but they were driven on highways in South Africa. The U.S. military took them off road.”
Many of the MRAP manufacturers have sought to upgrade those vehicles with independent suspensions and have turned to AxleTech to accomplish that feat. “We have a long history of building and producing independent suspensions,” said De Veny. “We are one of the largest independent suspension manufacturers in the world.” AxleTech has provided thousands of independent suspensions to the RG31 and MaxxPro MRAP variants.
In the 1990s, AxleTech provided independent suspensions to the Textron M117 armored security vehicle and the Bushmaster protected mobility vehicle, “so we were well-positioned in technology when MRAP vehicles started to make the switch from solid to independent suspensions,” said De Veny. “MRAPs were first brought in for protection and survivability. Once we had the time, we were able to go back and upgrade the vehicles with independent suspensions. Now the MRAPs are able not only to protect their occupants but to provide great ride quality. It’s like the difference between a 1970 pickup truck and 2011 passenger sedan.”
De Veny predicts that independent suspensions will soon make it to lighter tactical vehicles such as the HMMWV. As these vehicles get heavier with armor and payload, they require heavier axles, and at some point the axle to payload ratio can “affect the vehicle architecture.”
AxleTech has provided independent suspensions to the United Kingdom’s Ocelot tactical vehicle. De Veny believes AxleTech can find a niche among U.S. tactical vehicles as well. “I wouldn’t expect them to go across the entire fleet,” he said, “but in certain niches such as special forces that have high speed and maneuverability requirements.” ♦