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Advanced Composite Cargo Aircraft gets X-plane designation

  • Published
  • By Derek Kaufman
  • 88th Air Base Wing Public Affairs
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  Air Force officials have approved X-55A as the new designation for the Advanced Composite Cargo Aircraft.

The X-55A is a technology demonstrator for the design and manufacture of future aircraft using advanced composite materials. The X-55A is a modified Dornier 328J aircraft with the fuselage aft of the crew station and the vertical tail removed and replaced with completely new structural designs made from composites using new out-of-autoclave curing techniques. The test platform contains some 600 accelerometers and stress gauges. Its first flight was June 2, 2009 at Air Force Plant 42 in Palmdale, Calif.

"We're extremely proud to have been awarded X-designation," said Barth Shenk, X-55A program manager with AFRL's Air Vehicle Directorate. "We hope to take this testing to the next phase to further mature our understanding of composite materials, how they behave in flight and how they age. This effort may drastically change the way we manufacture future military and civilian aircraft."

The strength, light weight, ease of manufacture and corrosion resistance are just some of the composite materials characteristics Air Force officials want to use the X-55A to explore, Mr. Shenk said.

The X-55A was made possible by a 10-year Air Force Research Laboratory-led research and development investment called the Composite Affordability Initiative. Government labs including NASA worked collaboratively with industry to develop advanced materials and manufacturing technologies, Shenk said.

The ACCA was conceived by AFRL as a fast-track, low-cost development effort. Working with Lockheed Martin's Skunk Works, it was designed in 5 months, then built and flown 20 months after the go-ahead. Shenk said it was built at half the estimated cost of a conventional design of the same size.

Test flights on July 13 and August 8 expanded the aircraft's maneuver envelope and recorded external aerodynamic flow data.

Phase III of the program was awarded on Sept. 17, to Lockheed Martin and plans to include fully expand the flight envelope and characterize the structure, examine reliability and longevity of the design, and baseline the X-55A as a test-bed for other technologies.

According to Shenk, the X-55A program already has demonstrated the feasibility of designing and manufacturing large, bonded unitized structures featuring low-temperature, out-of-autoclave curing. The fuselage was constructed in two large half-sections (upper-lower) featuring sandwich construction with MTM-45 skins and Nomex core, bonded together with adhesive and ply overlays along the longitudinal seam rather than numerous frames, stiffeners and metal fasteners used commonly in traditional aircraft. The vertical tail was designed using tailored stiffness technology. These were joined with an existing Dornier 328J cockpit, wing, engines and horizontal tail.

Compared to the original metallic components, the composite structure uses approximately 300 structural parts versus 3,000 metallic parts for the original components and approximately 4,000 mechanical fasteners compared to 40,000.

(Robyn Dinwiddie of the Air Force Research Laboratory contributed to this article).