Advanced Composite Cargo Aircraft.
The X-55A is a technology demonstrator for the design and manufacturing
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. These designs are made from composites using new
out-of-autoclave curing techniques. The test platform contains some 600
accelerometers and stress gauges.
The aircraft's 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 the Air Force Research Laboratory'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 AFRL-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, Mr. 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. The
aircraft was built at half the estimated cost of a conventional design
of the same size, according to Mr. Shenk.
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 to Lockheed Martin Sept. 17 and
plans to 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 Mr. Shenk, the X-55A program has already 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.
Derek Kaufman (AFNS)
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