When the Army decided to trim down the weight of the Crusader field
artillery system by 20 tons, the prime contractor redesigned the
vehicle in less than seven months. What made this possible, officials
said, was the sophistication of the manufacturer’s computer-aided
simulation technology.
By Pentagon standards, seven months is an unusually fast turnaround
for a major weapon system redesign. Before digital design technology
became the norm in vehicle manufacturing, making such drastic changes
in engineering drawings would take several years.
Computer-aided design has been around for decades and is used in
most Pentagon weapon programs today. But Crusader officials claim
that they have pushed this technology farther than other defense
programs or other industries, such as the automotive and aeronautical
design.
The Crusader field artillery program, made by United Defense LP
(UDLP), in Minneapolis, began in 1994. It was designed to replace
the aging Paladin self-propelled howitzers currently in the Army
inventory. The system consists of a self-propelled howitzer and
an ammunition resupply vehicle. The two pieces weighed 110 tons,
which was acceptable in the early stages of the program.
But approximately 18 months ago, the Army announced it would undergo
a so-called "transformation" process to become a lighter,
more mobile force. That meant Crusader had to be slimmed down, or
it would not fit into the Army’s war-fighting strategy.
At UDLP’s armaments division in Minneapolis, engineers, designers,
number- crunching executives and Army officers have been watching
the redesign unfold in front of their eyes at the company’s
"visual integration lab."
Major modifications were made on both vehicles. The 55-ton howitzer
was trimmed to about 40 tons (not including armor kits and ammunition).
Half of the resupply vehicles, which initially were tracked, will
be wheeled.
The U.S. Army spent $355 million on Crusader this fiscal year.
The visual integration lab, which was installed in 1998, is one
among only 35 such facilities in the United States, said David Crowell,
the company’s marketing manager. Typically, this type of facility
would be found in the entertainment industry, Crowell told reporters
during a tour of the plant last month.
"The big thing that this allows you to do is work in real
time," he said. Computers process massive amounts of engineering
data, allowing Crusader officials to "see how it ought to work
before you do any simulations. ... We reduced the acquisition cycle
for major systems by a third."
The visualization technology facilitates easy "what-if"
iterations of different design changes, explained Crowell. "We
can strip it down and build it back up. ... Within two months, we
were able to tell the Army whether we could take the 20 tons off
the vehicle. Within seven months, all the design options had been
completed."
The computer-aided engineering design tool used for Crusader is
a commercial software package called Pro-Engineer. "We take
the master data base–the design of the Crusader–and
we bring in the [software] tool and then run the system and subsystems
in real time," Crowell explained. Crusader’s design has
more than 2 million lines of software code. The tools also are commercial
software, called dVISE version 6.0.2 and dVMockup.
During a demonstration for reporters, UDLP engineers ran a "visualization
sequence" which showed the three components of the system:
the howitzer and both the tracked and wheeled resupply vehicles.
Because the digital mockups exactly replicate the real vehicles,
Crowell said, "we could achieve a great deal of confidence
in the redesign and that it’s going to work.
"All the tools are linked by a dynamic object model,"
Crowell said. UDLP simulation experts designed that model. "That
is the glue that holds all of the timelines and the designs together
so we can actually operate and understand the behavior" of
the Crusader system.
The same technology had been used to design the original, heavier
Crusader. But when it came time to overhaul the design, Crowell
said, "We pushed the envelope on virtually every design tool
that exists."
UDLP engineers often have invited the various software developers
of the design tools to the lab "to discuss how their tool has
to be better to do what we want to do," he said. "We made
those companies [improve] those tools."
Before the redesign, Crusader was scheduled to join Army units
by 2005. Congressional funding cuts, as well as the redesign, pushed
that deadline to 2008. Nevertheless, said Crowell, "I don’t
think anyone can beat the design cycle we’ve got going right
now."
Unlike any other howitzer in the Army today, Crusader has a fully
automated capability to load the 100-pound rounds inside the howitzer
and inside the resupply vehicle. The design of thousands of moving
parts has to be perfect to avoid break-downs and jams during firing
operations. The system has no manual back-up, so "reliability
is a huge issue," said James E. Unterseher, Crusader’s
program director at UDLP. The precision of the digital design tools
help achieve those demanding parameters, he said. That is how the
company has been able to run more than 25,000 tests, Unterseher
told National Defense.
Changes made to take 20 tons off the weight of Crusader:
Its redesign notwithstanding, the future of Crusader remains unclear.
Defense Secretary Donald Rumsfeld directed a Pentagon-wide review
of weapon programs, and Crusader will be among the most scrutinized
systems, said defense experts. One problem, several experts said,
is that the Army has not articulated specifically what role Crusader
will have in the future force.