November 05, 2012
Credit: Boeing Concept
Graham Warwick Washington
No one could accuse the U.S. Defense Advanced Research Projects Agency of lacking imagination. But to rethink the entire design, development and manufacturing process used by aerospace for decades is ambitious, even for the agency that helped bring us GPS, the Internet and stealth.
Under the Adaptive Vehicle Make (AVM) program, Darpa is working to combine model-based design, virtual collaborative engineering and foundry-style manufacturing into an end-to-end process that cuts development timescales by a factor of five, eliminating the design-build-test-redesign cycle that is driving costs and delays.
“It's safe to say that the direction we have been going in military acquisitions is not a sustainable path,” says Lt. Col. Nathan Wiedenman, Darpa AVM program manager. “We simply can't continue to spend more and get less for the money we spend.”
He points to a 2010 review that concluded the U.S. Army had spent $22 billion over the previous 15 years on programs that were eventually canceled—and to “Augustine's Laws.” In 1984, former Lockheed Martin Chairman Norman Augustine looked at cost trends and predicted that, within 50 years, the entire U.S. defense budget would buy one tactical aircraft. “He wrote that book 20 years ago and we have hewed to those trends ever since.”
Darpa blames the limitations of today's design methods. These break a system down along engineering disciplines (structural, thermal, etc.), optimize the parts and subsystems for their individual tasks, then put them together. “After we build it, we test it, to see if it works the way we expected. Invariably it doesn't, because all those components and subsystems interact in ways we couldn't anticipate.”
Nothing is just a power or thermal system. “All have behaviors that affect the components and subsystems around them. Things overheat or vibrate loose because it would take too much computation to predict and evaluate all those interactions. That means we have to go back and redesign, rebuild and retest,” he says.
The problem is complexity, Darpa believes. “Even though the systems we are building are much more complex, the way we engineer those systems has not fundamentally changed for about 50 years,” Wiedenman says. Industry is embracing model-based design, but AVM takes another step, using component models for design, context models for virtual testing, and manufacturing models to provide automated feedback on cost and schedule.