Composits come to air transports

USA Today:

In a high-security compound where some of the world's most exotic aircraft were born, engineers and technicians are building a prototype for a new Air Force cargo plane that may change aviation.

Lockheed Martin is building the first military cargo jet in which the craft's structure will be made of fibers, resins and epoxy, replacing metals such as aluminum and titanium that have been in use in aircraft for decades.

The composites hold huge potential for saving weight, a critical factor in aviation performance and fuel consumption, aviation experts say. The goal is to put the test plane in the air by October, one year after the $50 million contract was awarded — and just 18 months after the concept took shape, a record time for the military.

"This is fundamentally a different way of building aircraft," says Mike Swanson, project lead engineer. "We're going up against 70 years of traditional metal fabrication."

Non-metal parts have been used in commercial and military aircrafts for more than a decade. But the Air Force says the new Advanced Composite Cargo Aircraft will be the first military transport to incorporate the latest fiber technologies and production methods in the airframe itself.

Ken Miller, assistant secretary of the Air Force for acquisitions, said expected savings of 20% to 30% in weight will translate to similar savings in fuel. While that can reduce costs, a bigger payoff for the military is being able to fly heavier payloads for longer distances.

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There are other benefits besides potential significant fuel savings, Swanson said during an interview at the Lockheed Martin facilities where the plane is being built:

• Improved performance and durability: Fiber materials resist corrosion and eliminate metal fatigue, factors that force major rebuilding of military aircraft after 20 to 30 years of hard use.

• Fewer parts: The number of parts will be reduced by at least 90% if, as planned, 306 composite parts replace up to 4,000 metal ones. The Air Force can't say if building planes with composites will be cheaper than metal. But lowering costs of producing composites through new manufacturing methods is a goal, Miller says.

Speeding up the lengthy process of getting a plan from concept to reality may also help with costs.

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Composites have been used in racing sailboats for years where weight has a dramatic effect on speed. However composites can be subject to fatigue also. One advantage to composites is that they can be molded more easily into ergonomic shapes. You can see the benefits of this in most newer vehicles.