Array of Army Hybrid-Drive Vehicles Expanding Steadily.

• Author: Erwin, Sandra I.

Air-defense and missile-firing configurations of the Army's Humvee truck would be ideal candidates for a novel propulsion system known as hybrid-electric drive, officials said.

Customized trucks that carry anti-ballistic missile interceptors, such as the Army's theater high-altitude area air defense (THAAD), could benefit from this propulsion technology, which provides a quiet ride and generates additional electrical power, said Army and industry officials. Other specialty trucks where hybrid-electric propulsion would make sense, for the same reasons, are the Striker fire-support vehicle and the LOSAT (line-of-sight antitank) missile platform.

The Striker surveillance and targeting vehicle, built on a Humvee chassis, consists of advanced sensors, communications systems and a machine gun. The LOSAT kinetic-energy missile is used by light infantry units and also is mounted on a Humvee.

The Humvee is the Army's high-mobility multipurpose tactical wheeled vehicle.

All three special configurations of the Humvee are "possible users" of hybrid-electric propulsion, said Randall Gaeremick, deputy for systems acquisitions at the Army's TankAutomotive and Armaments Command.

Although hybrid-electric designs for passenger cars and mass transit buses have proved successful, officials noted that military vehicles present a host of unique demands.

Having a large electric-power source onboard would help meet the high energy demands of vehicles such as the THAAD, Striker or LOSAT platforms, said Ken Winters, vice president of PET Electronics, in Huntsville, Ala. The company developed a hybrid-electric propulsion system for the Humvee.

A hybrid propulsion unit includes a conventional engine, generator, a battery pack and electric-drive motors.

The Army currently is testing two hybrid-electric Humvees at the Aberdeen Proving Ground, in Maryland and at the Nevada Automotive Test Center. The plan is to build eight to 10 more prototypes by 2002, Gaeremick said at an industry conference in Monterey, Calif. A heavier truck, called the "extended-capacity" Humvee also is being tested with a hybrid-electric drive and could be available by 2004.

The new vehicles are funded under two separate programs. One is managed by the Humvee original manufacturer, the AM General Corp. PEI provides the power-train components that are needed to convert Humvees to hybrid-electric drive, Winters said in an interview. The other contract is with the Army's Tank-Automotive and Armament's Command's research and development center.

One of the two existing prototypes is a Humvee with a four-motor drive. An individual motor drives each wheel. "That gives it the highest possible performance we can get in that vehicle," said Winters. "It's very efficient for operations in sand, mud, because you get very good traction when the wheels are controlled individually, rather than going through a mechanical differential."

The second prototype is a utility Humvee, with a two-motor design. It has 30 percent less horsepower and uses a mechanical differential. "It doesn't have quite the mobility or the performance of the four-motor drive," said Winters. "But it is still better than the standard Humvee."

The next set of vehicles will be more sophisticated, he said. They will incorporate advanced features that the Army is considering for its next-generation Humvee, the A4 model. "We'll incorporate lessons learned from the testing from the first two vehicles," said Winters.

PEI officials hope to receive a production contract in mid-2004 or 2005.

Customized systems such as THAAD, Striker and LOSAT make fitting candidates for hybrid-electric Humvees, which come with a 75-kilowatt generator and large battery pack, he explained. "When you are not driving the vehicle, you can use that electric power for other applications."

If the Army deployed a mobile tactical operations center, for example, soldiers could draw power from the vehicle rather than bring a generator, Winters said. "It's a logistics savings. It allows you to plan on the move. It reduces logistics footprint and saves weight."

The unanswered question, however, is cost. "We really don't know yet," said Winters...