Confronting growing fuel and transportation costs, the U.S. Army has no choice
but to start fielding fuel-efficient trucks, officials said. The Army, additionally,
needs to find ways to control the escalating expenses associated with maintaining
a fleet of nearly 240,000 trucks.
One way to do that is to have “fewer, but more capable trucks,”
said Maj. Gen. N. Ross Thompson III, head of the Army Tank-Automotive and Armaments
Command. In the long term, he said, the Army will be able to save billions of
dollars in logistics-related costs by consolidating the number of truck types
it uses currently and by adopting hybrid-electric vehicles.
“If the trucks are more capable, you don’t need as many of them.
Even if they are more expensive and more capable, you can still save by having
fewer drivers, mechanics and handlers,” Thompson said in an interview
during a conference hosted by the National Defense Industrial Association, in
The Army obviously will not be able to just have one type of truck, he noted.
It always will need light, medium and heavy trucks. “There will be a range
of sizes, but as much as possible, common components across all the fleets.”
The current fleet of 238,000 trucks, over time, will become smaller, “unless
the Army goes up in size,” said Thompson.
Between 1987 and 2007, the Army’s heavy truck fleet will grow from 20,000
to 30,000 vehicles. The medium fleet, meanwhile, will shrink from 206,000 to
83,000 and light trucks will go from 174,000 down to 124,000. Annual funding
for truck programs is about $1.2 billion. This account is expected to rise to
$2 billion by 2007.
Thompson is adamant about the Army’s need to replace gas-guzzlers with
fuel-efficient vehicles, likely to be diesel-electric hybrids, he said. “I
think there should be a 50 percent fuel-efficiency requirement in current vehicles.
“If I have a truck that gets 30-50 percent fuel economy, then I don’t
need as many 5,000-gallon fuel tankers [or] as many fuel handlers. If I have
on-board load-handling equipment to do the lifting, I don’t need the cranes
In hybrid power drives, the methodology for generating power can either be
through an internal combustion engine (gas or diesel), turbo shaft (turbine),
fuel cells or all electric (batteries only).
For military vehicles, experts agree the most desirable system is a hybrid-diesel,
where a small diesel engine powers a generator and charges the battery. This
technology provides on-board electric power, which means that the Army would
bring fewer generators to the battlefield, said Thompson. In a word of advice
to the industry, he added, “I don’t think that I would invest in
generator companies that support the U.S. Army, or in trailer companies that
are used to transport generators.”
The Army goes through 200 million gallons of fuel a year, resulting in annual
expenses of $3.5 billion, including transportation and labor. Even nominal savings
in fuel consumption could result in significant cost reductions, Thompson said.
Fuel and water currently constitute about 60-90 percent of the short tons the
Army takes to the battlefield. Further, about 55 percent of the fuel is consumed,
not by the front-line forces, but in the echelons above corps and rear units.
The Army Brigade Combat Teams, each with 959 vehicles, would greatly benefit
from hybrid power drives, he said. According to a TACOM study, if all the vehicles
in the brigade were hybrid, the unit would increase its range by 180 miles on
a single tank of fuel, and would need 4,000 fewer gallons of fuel for every
Of the top 10 battlefield fuel users in the Army, said Thompson, four are trucks:
the heavy line haul truck, the medium tactical truck, the heavy-equipment transport
and the Humvee.
Despite the enthusiasm about hybrid-electric vehicles, Thompson acknowledged
that the Army is not quite ready to accept this technology for combat use, and
it may not be for several years. Hybrid drives have yet to become mainstream
in the U.S. automotive industry, so it’s not yet clear how long it will
take for this technology to mature. Hybrid-electric vehicles also cost more
and weigh more than conventional diesel-powered trucks, so the Army needs to
study how the cost and weight penalties can be offset. Additionally, said Thompson,
not enough testing has been done to bear out the reliability of hybrids, particularly
in the area of energy storage and power electronics.
The National Automotive Center, a subordinate organization to TACOM, has been
an advocate of hybrid-electric vehicles for several years and has sponsored
projects to develop hybrid versions of the M113 armored vehicle, the heavy-duty
HEMTT truck, the Light Armored Vehicle, the 2.5-ton medium Army truck and a
heavy line-haul tractor trailer. But those programs remain in the experimental
phase. Among the most promising hybrid-electric vehicle projects in the Army
today are the Humvee and the Combatt, which stands for commercially based tactical
The Combatt program—spearheaded by the NAC—is a partnership with
General Motors, Daimler Chrysler and Ford, to upgrade commercial pickup trucks
and SUVs so they can be suitable for military use. Congress gave the NAC $14
million in fiscal 2002 to upgrade up to 18 vehicles (six from each manufacturer)
with hybrid electric drives.
“The NAC is the Army’s venture capital company,” said Thompson.
“They are creative individuals [who] make people uncomfortable sometimes,
because they are out there pushing ideas and pushing technologies that force
people in a particular business to look at things differently.”
With funds from the Combatt program, Daimler Chrysler produced a diesel-electric
hybrid Dodge Ram 2500 pickup truck. The vehicle can be operated in either diesel-electric
hybrid or electric-only mode. When parked, the drive components can be used
to provide up to 20 kilowatts of continuous electrical power to operate other
The company plans to sell the Dodge Ram HEV commercially beginning in 2004.
The hybrid power train, said a spokesman, improves fuel efficiency by up to
20 percent and curbs tailpipe emissions.
TACOM received $3 million in fiscal 2002 to build two hybrid Humvees and test
them for 20,000 miles at the Aberdeen Proving Ground.
The plan is to procure 106 hybrid Humvees by 2007, even though, said Thompson,
“I think that number needs to be 100 times that.”
To raise the visibility of the project, TACOM established a program office
for the hybrid-electric Humvee. Assistant program manager Steve Roberts said
in an interview that the goal is to eventually “hybridize” 10 percent
of the Humvee fleet.
Those vehicles would be assigned to “missions that require a great amount
of stand-by electrical power and where stealth is important,” said Roberts.
AM General Corp., the Humvee manufacturer, currently is working with PEI Electronics
to produce four hybrid vehicles.
To make a hybrid Humvee, the engine, transmission and transfer case are removed
and replaced with a smaller engine, generator, battery pack and electric traction
motors. The hybrid Humvee is a battery dominant system, “which means we
use the battery energy to level the road-load power required to achieve a specific
level of desired mobility,” said Don Underwood, vice president of PEI
Electronics, in Huntsville, Ala. “This also provides a significant amount
of energy density for military applications like silent watch, or support of
command and control operations, without operating the engine or generating a
Other hybrid systems may be engine dominant, which require the engine to operate
The program’s goal is to demonstrate a 30 percent reduction in fuel consumption
and the ability to generate 33 kilowatts of power off the vehicle, Roberts explained.
That would be enough power to run an Army operations center or a missile-defense
The current hybrid drive in the Humvee achieves 15 percent fuel economy, according
to PEI Electronics. That percentage was based on an average gross vehicle weight
of 7,500 pounds during highway operations averaging 55 mph, said Underwood.
“As speed is decreased and the amount of dynamic pressure (resistance
of pushing air as a function of surface area and the square of the vehicle speed)
decreases, the average fuel economy increases proportionally to a maximum of
26 miles per gallon at 16 mph,” as measured on a cross-country course
at the Army’s Aberdeen Proving Ground, in Maryland.
Underwood said that the industry’s goal is to limit the cost of hybrids
to approximately 25-40 percent above the cost of a conventionally powered vehicle.
“This is always highly dependent upon power density and cross-country
mobility requirements,” he said.
After the current development-test phase is completed, TACOM will solicit industry
bids to build more hybrid Humvees. AM General is the only Humvee manufacturer,
but there are several companies that make hybrid-electric drive technologies.
“We’ll develop performance specifications,” said Roberts.
“We will not tell the contractor how to build the vehicle. We would buy
the chassis from AM General but another contractor would provide the hybrid
Roberts’ office is working in cooperation with the Army’s program
manager for mobile electric power. “They are helping define the requirements
for off vehicle power … and will be assessing the impact of hybrid-electric
vehicles on the Army’s generator fleet.”
The issue of fuel-efficiency in Army trucks was discussed extensively by most
speakers at the 2002 NDIA tactical wheeled vehicles conference. But not everyone
agreed that it should be a top priority in the Army.
“This organization [the Army] does not exist to be fuel efficient,”
said Lt. Gen. John S. Caldwell, military deputy to the Army’s assistant
secretary for acquisition, technology and logistics.
But he acknowledged that the Army must take action to cut back on fuel use.
“I appreciate the brain power being brought forth by Gen. Thompson on
fuel efficiency,” Caldwell told the conference. But the most important
function of the Army, he stressed, is to “deliver lethality.”
A congressional staffer who also spoke at the conference said that many lawmakers
support the use of hybrid-electric vehicles in the military services, but he
cautioned that “there is a perception that batteries are too big, heavy,
dirty [hard to dispose].”
Tom Edwards, deputy chief of the Army’s Combined Arms Support Command,
also warned Army officials attending the symposium that they need to articulate
their expectations about hybrid-electric technology, so companies don’t
end up delivering false promises and unrealistic sales pitches.
All too often, said Edwards, companies oversell technologies. This applies
to hybrid-electric vehicles, which advertise 50 percent fuel savings but only
deliver 20 percent.
The issues associated with fuel-efficiency are complex and require more than
just adding a hybrid drive, noted Goef Schmitz, president of Island City Engineering,
in Schofield, Wis. The company works on various military truck programs.
“The solution will not result from pursuing a single technology, a magic
bullet,” he told National Defense. “The key is to understand the
vehicle’s mission, the terrain and overall efficiency across the combat
logistic environment,” including the weight of the cargo and the type
of load-handling equipment used.
For the Army’s logistic truck fleet to become more efficient, said Schmitz,
vehicles should be designed with increased mobility, to match available technology.
With additional mobility, he said, “We can anticipate increasing logistic
truck speeds over cross-country and off-highway terrain two to five times.”
Similarly, vehicle payload requirements should match available truck technology,
Schmitz noted. The Army also could mandate that manufacturers reduce vehicle
weight and improve fuel economy, without dictating how to reach those goals.
Schmitz said he believes the Army should reevaluate the need for non-payload
equipment aboard logistic vehicles, such as load-handling equipment, winches,
pallets, flat-racks, containers and spare tires. “Every pound of dead
weight is fuel, ammunition, and water not carried,” he said.
While no single technology will address the fuel consumption problem, he added,
incremental steps can help. For example, he explained, the use of synthetic
lubricants can achieve 3 to 6 percent increased fuel economy in commercial truck
Hybrid vehicle technology, no matter how effective, also must live by the laws
of thermodynamics, said Schmitz. “No more energy is available in hybrid-electric
systems than is available from the prime-mover power sources, in most cases,
a diesel engine.
“There is an unavoidable energy loss when engine power is converted to
electrical power. A second loss occurs if energy is stored, a third when removed
from storage and a fourth when converted back to mechanical power to drive the
axle,” he added.
The fuel savings are largely vehicle duty-cycle dependent. Electric hybrids
can deliver impressive performance and fuel economy within a limited, predictable
duty-cycle, said Schmitz. “For well-defined commercial, vocational truck
and perhaps even in limited line-haul military applications, there may exist
a case for electric hybrids.” Duty cycles, he stressed, should be based
on real-world mission scenarios. Commanders, ultimately, must decide whether
they will require “access to full power at any time, all the time [and
whether they can] wait for the batteries to recharge.”