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Army to test electric tactical vehicle

Electricity has been the military’s fuel of choice for the very large (2,500-ton submarines) and the very small (12-pound unmanned aerial vehicles), but not for the vast middle ground of tactical vehicles.

A vehicle maker hopes to change that with the HEMTT-A3, a hulking hybrid truck. Oshkosh Corp. says the vehicle consumes 20 percent less fuel, requires less maintenance than current trucks and can double as a power source for field hospitals or command centers.

Dubbed the “heavy expanded mobility tactical truck,” the vehicle is headed to Army proving grounds this fall to undergo durability, reliability and performance tests.

The U.S. has spent years testing vehicles that run in part or entirely on electricity, said Paul Skalny, director of the Army’s National Automotive Center. So far, the service has not embraced them.

The Army has a few hybrid electric Humvees for testing — “probably less than 10,” Skalny said. And it has tested hybrid utility vehicles, maneuver vehicles and fuel-cell-powered vehicles.

But they haven’t generated wide enthusiasm.

“There are no tactical hybrids in the military today,” Skalny said. Oshkosh is optimistic that its vehicle may be the first.

Unlike some hybrids, the HEMTT-A3 runs solely on electricity; there is no parallel mechanical drive train. A diesel generator produces electricity, which powers electric motors that drive each of the vehicle’s four axles, said Gary Schmiedel, Oshkosh’s vice president for advanced product engineering.

The generator also produces electricity that is stored in two dozen ultracapacitors. Ultracapacitors can be recharged and discharged several million times without wearing out, Schmiedel said.

The HEMTT-A3’s power train provides for more flexible vehicle configurations. That has freed space for a 40 percent larger cab and allowed engineers to cut 3,000 pounds of weight off the 38,000-pound curb-weight vehicle.

The extra cab space and the abundant power supply make it possible to outfit the truck with additional communications gear, computers, GPS receivers and other equipment.

Fuel savings increased to 33 percent when the vehicle was driven with lots of stops and starts. Stops and starts usually kill fuel efficiency, but in the HEMTT-A3, the stops generate electricity.

The truck also is capable of loading and unloading itself. It can “pull up to a C-130 and unload the plane without additional equipment,” Schmiedel said.

The Army also is attracted to hybrids for their ability to travel silently on stored electricity.