|
The vertical tail features
integrally stiffened skin. Despite its larger size, the
materials and processes used for the fuselage reduced the number
of parts by an order of magnitude relative to the original
metallic design (approximately 300 versus 3,000) and drastically
reduced the number of mechanical fasteners (about 4,000 vs.
30,000), program officials said.
The flight marks the final and most significant milestone of
Phase II of the Air Force Research Laboratory ACCA program, said
Barth Shenk, an ACCA program manager from AFRL's Air Vehicles
Directorate at Wright-Patterson Air Force Base.
"This has the potential to change aircraft manufacturing as we
presently know it, for the better," Mr. Shenk said. "Today's
successful flight is the culmination of years of teamwork
between government and industry labs involving hundreds of
dedicated researchers across the country to fundamentally change
the way we make airframes."
Lockheed Martin officials said the ACCA took-off to the east
from Air Force Plant 42 at 6:55 a.m. Pacific Time. The aircraft
then banked west and climbed to an altitude of approximately
10,000 feet where the two-pilot crew took the vehicle through a
series of airspeed and stability and control tests. Officials
said the tests are important to understand how the composite
cargo aircraft performs at varying speeds, attitudes, and
altitudes. This data will be used as a baseline for future
tests.
"Today is one of those perfect days where I get to be the first
to fly a new aircraft and everything goes exactly as planned.
The aircraft was a real pleasure to fly and we experienced
absolutely no issues," said Rob Rowe, the Lockheed Martin lead
ACCA test pilot. Duration for the first flight was about 87
minutes.
Mr. Shenk said the ACCA isn't designed to be a prototype for a
small airlifter or any other aircraft. It is a proof of concept
technology demonstrator for composite manufacturing processes in
a full-scale, certified aircraft. In an effort to demonstrate
and test the technologies while keeping costs down and on
schedule, the small team of Air Force and Lockheed Martin
engineers elected to modify the high-wing Dornier jet, mating
its existing engines, wing, landing gear and avionics systems to
the new composite structure. The modified fuselage has enlarged
rear cargo doors and can accommodate two standard size military
pallets.
The new composite structure is manufactured without complex
tooling and the bonding process yields a 90 percent reduction of
structural components and fasteners, said Frank Mauro, the vice
president of Advanced System Development for Lockheed Martin.
"Historically aircraft cost has been generally determined by the
size and weight of the vehicle. With ACCA we are proving that
while size does matter, it isn't the be-all, end-all
determination of aircraft cost," Mr. Mauro said.
Lacking traditional fasteners like rivets, the composite
structure is inherently aerodynamic. Mr. Shenk said he believes
composite structures will address many of the corrosion and
aging issues associated with all-metal aircraft, reducing
airframe lifetime maintenance. Lighter weight of composite
materials can also contribute to increased cargo capacity,
aircraft performance and lower operating costs. The real game
changer; however, is the maturation of manufacturing processes
which collectively dramatically reduce the cost and complexity
of building large airframes.
The ACCA's first flight was made possible by a 10-year Air Force
Research Laboratory-led research and development investment
called the Composite Affordability Initiative. Government labs
worked collaboratively with industry to develop advanced
materials and manufacturing technologies, Mr. Shenk said.
The ACCA's large composite sections are essentially formed,
cured and bonded together in room-sized ovens, instead of using
expensive autoclaves, which use a combination of heat and high
pressure. Out-of-autoclave curing of large, unitized and
co-bonded structures minimizes part count. The "ripple effect"
of this approach contributes to costs reduction across every
aspect of airframe production, Mr. Shenk explained. Tooling, raw
materials, fabrication man-hours, quality control and floor
space utilization efficiencies are realized. Together, they
combine to greatly reduce cost, design and manufacturing
complexity.
"ACCA is the capstone test of integrating these composite
affordability initiative principles all the way from conceptual
design through certification and flight," Mr. Shenk said.
"NASA Dryden Flight Research Center and AVCRAFT have been
linchpin partners in our program's success" Mr. Shenk added.
"NASA's expertise in experimental flight test programs helped us
streamline our test preparations and AVCRAFT (the Myrtle Beach,
S.C. based domestic maintainer of Dornier 328J), provided
critical support on the aircraft subsystems so Lockheed could
focus on the structural design, fabrication and integration
issues."
The ACCA test aircraft is laden with more than 600 sensors and
accelerometers to measure stresses on its structure. Upcoming
tests will focus on establishing the flight envelope of the ACCA
to baseline its flight performance and validate predicted
structural performance. "Accurately predicting structural
behavior in the flight environment is a key step in establishing
the eligibility of the technologies for transition into future
programs, to fully realize the cost savings demonstrated by the
ACCA," Mr. Shenk said. |
