U.S. Army Fuel Efficient Demonstrator (FED) Bravo concept diesel hybrid-electric vehicle, April 2012
For U.S. armed forces, green is mostly seen these days as accents in beige battlefield camo.
But reducing the cost and risk of delivering very expensive diesel fuel in vulnerable military convoys has long been a Pentagon goal, and one way to do that is to make all military vehicles more fuel efficient.
Last week, the U.S. Army displayed its Fuel Efficient Demonstrator (FED) Bravo concept vehicle at the annual Society of Automotive Engineers (SAE) World Congress in Detroit.
With a 268-horsepower, twin-turbocharged 4.4-liter V-8 diesel engine from Ford, the 16,760-pound FED Bravo sports a six-speed automatic transmission and hybrid drive for the rear axle, plus an electric motor to power the front wheels.
Its lithium-ion battery pack powers the motors, which can also act as generators to recapture otherwise wasted energy during regenerative braking.
Like all full hybrids, the FED Bravo will switch off its engine when stopped, with the battery pack providing power for systems that keep running. It can travel up to 5 miles on electric power alone.
A combined hydraulic system serving both the braking and steering system reduces parasitic losses, and the carbon-ceramic brake rotors weigh far less than conventional steel brake disks.
The result is that the FED Bravo prototype is twice as fuel-efficient as the traditional Humvee whose duties it is designed to take on. The Army says it achieves 8.2 mpg in city usage and 14.2 mpg on the highway, versus the 3 to 6 mpg delivered by a Humvee.
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This is the second FED concept; the Alpha version last fall lacked the power export capabilities of this latest version, an important feature that allows soldiers to use the FED's battery pack as a power source to run power tools and other gear.
The concept personnel carrier was developed by engineers at the Army's Tank Automotive Research, Development and Engineering Center (TARDEC) in Warren, Michigan, with design input from students at the Center for Creative Studies in Detroit.
While the FED Bravo is strictly a concept at this point, elements of its technology are likely to be built into future military vehicle programs.
And it's hardly the only military hybrid. The Army has previously displayed a prototype Clandestine Extended-Range Vehicle (CERV) that also uses a diesel hybrid-electric powertrain.