X-48/X-48B
Specifications Company-
The Boeing Company; Cranfield Aerospace Type-
Blended Wing Body (BWB)
Goals- Study flight
characteristics of blended wing body (BWB) designs.
Primary Testing Facility
Research- Edwards AFB Dimensions-
Span- 35 ft, 0 in Max Speed- N/A Range-
N/A Service Ceiling- N/A Power Plant- N/A Thrust- N/A Weights-
N/A Payload- N/A Flights- N/A Number of Prototypes Built-
2 (2 X-48B) Project Tenure- 2000-???? Project Status-
Ongoing Information
Boeing Phantom Works has studied Blended Wing Body
(BWB) aircraft concepts. In a continuing effort to study the flight
characteristics of the BWB design, a 17-foot wingspan, remote controlled
model has been successfully flown. The X-48, a 35-foot model, was built
at NASA 'a Langley Research Center. Test flights of this scale,
1,800-pound model are scheduled to begin in 2004.
The Blended Wing Body offers greater structural,
aerodynamic and operating efficiencies than today 's more conventional
tube-and -wing design. Its modular design also allows for center body
growth while maintaining common wings. These features translate into
greater range, fuel economy, reliability and life cycle savings, as well
as lower manufacturing costs. They also allow for a wide variety of
potential military and commercial applications.
The Blended Wing Body (BWB) is a hybrid shape that
mainly resembles a flying wing, but also incorporates some features of a
conventional airliner. The futuristic airframe is a unique merger of
efficient high-lift wings and a wide airfoil-shaped body, causing the
entire aircraft to generate lift and minimize drag, thereby increasing
fuel economy. Passenger and cargo areas are located within the center
body portion of the aircraft.
NASA and industry studies suggest that a large
commercial BWB aircraft could be developed to carry 800 or more
passengers; however, recent studies have focused on vehicles in the
450-passenger class. Because of its efficient configuration, the BWB
would consume 20 percent less fuel than jetliners of today, while
cruising at high subsonic speeds on flights of up to 7,000 nautical
miles. An aircraft of this type would have a wing span slightly wider
than a Boeing 747 and could operate from existing airport terminals.
One potential application is a BWB tanker for
performing multi-point refueling. Equipped with three smart booms, two
hose/drogue refueling points and automated refueling capabilities. A BWB
tanker would be able to accommodate simultaneous air-to-air refueling of
multiple conventional aircraft or UAVs. And because fuel would be
carried in wing tanks, maximum payload space would be available for up
to 23 conventional pallets and 40 troops.
As a C2ISR (Command, Control, Intelligence,
Surveillance, Reconnaissance) platform, the BWB would provide increased
loiter time, large interior space suitable for battle management control
rooms, and ample exterior locations for conformal phased-array antennas
for broadband communications with no increase in signature. These
capabilities make the BWB suitable as a long-range standoff weapons
platform as well. And should the market ever warrant a larger commercial
airplane, the BWB could be designed to accommodate up to 800 passengers
or more.
X-48A Blended Wing Body-Low-Speed
Vehicle
Problems in the development of the flight control
system as well as changing priorities at NASA led to the termination of
the X-48A program.
In 1997, Darrel R. Tenney, Director of the Airframe
Systems Program Office, initiated a series of in-house team studies to
determine if Langley could support the fabrication and development of a
series of unmanned, remotely controlled air vehicles that could be flown
to support Langley�s interest in revolutionary configurations. Langley�s
Director, Jeremiah F. Creedon, strongly supported the studies. At the
same time, Joseph R. Chambers� staff in the Aeronautics Systems Analysis
Division proposed a related new program based on the selection of
precompetitive advanced configurations that would be designed,
evaluated, fabricated, and test flown using remotely piloted vehicle
technology at Dryden. The program, known as Revolutionary Concepts for
Aeronautics (RevCon), would be based on a 4-year life cycle of support
for concepts selected. Initial reactions to the proposed program from
NASA Headquarters and Dryden were favorable, and following intercenter
discussions, a formal RevCon Program was initiated in 2000, which was
led by Dryden. Following a review of other advanced vehicle concepts by
an intercenter team, the team selected the BWB as one of the concepts
for further studies.
NASA was developing a 35-foot wing span,
remotely-piloted research aircraft based on the BWB design. The vehicle
is called the Blended Wing Body-Low-Speed Vehicle (BWB-LSV). The primary
goals of the test and research project are to study the flight and
handling characteristics of the BWB design, match the vehicle's
performance with engineering predictions based on computer and wind
tunnel studies, develop and evaluate digital flight control algorithms,
and assess the integration of the propulsion system to the airframe.
The Blended Wing Body research project is a
partnership between NASA's Aerospace Vehicle Systems Technology Program
and the Boeing Company. Funding and workforce for the project came from
both sources. In addition, the Flight Research Base Program at Dryden
Flight Research Center, Edwards, Calif., and Old Dominion University,
Norfolk, Va., are partners in the testing phase of this project.
During the late 1990s, wind tunnel and free-flight
tests have been conducted to study certain aerodynamic characteristics
of the BWB design. At the NASA Langley Research Center in Hampton, Va.,
researchers tested three wind tunnel models of the BWB-LSV to evaluate
the design's stability and control and spin/tumble characteristics. Data
obtained during these tests were used to develop flight control laws and
helped to define the flight research program. The researchers will
incorporate all of the wind-tunnel (and later flight) data into
simulations of the BWB-LSV and a full-scale BWB to evaluate the plane's
flying characteristics.
X-48A BWB-LSV Description
The BWB-LSV is a 14%-scale version of the
450-passenger study aircraft. Built primarily of composite materials and
weighing about 2,500 lb., the platform features a wide arrowhead-like
body that blends into tapered wings swept aft. Flight control surfaces,
or elevons, span the trailing edges of the wings while the rudders are
located in winglets on each wing tip.
Three 240-lb thrust turbojet engines, from Williams
International Corporation, Walled Lake, Mich., were mounted on low
aerodynamic pylons across the rear portion of the center body. All three
engines will operate from a single fuel tank located near the vehicle's
center of gravity. The maximum speed of the BWB-LSV would be about 165
mph.
Electric actuators in the flight control system
link the exterior control surfaces with a central digital fly-by-wire
flight control computer carried in the center body of the aircraft. The
aircraft was to be flown by a NASA research pilot sitting at a cockpit
station in the remotely piloted vehicle (RPV) facility at the NASA
Dryden Flight Research Center. Instruments and displays in the RPV
cockpit will provide the pilot with the same systems and performance
data commonly displayed in conventional research aircraft cockpits.
Two small video cameras was be installed on the
BWB-LSV. One, behind the mock cockpit windscreen, presents a
forward-looking view on a large video screen in the RPV cockpit station.
The NASA project pilot will use this view, along with the cockpit
instrument array, to fly the vehicle. The second camera was mounted atop
the rearward portion of the center body, to view external areas of the
vehicle during flight.
Numerous sensors installed throughout the vehicle
measure aerodynamic loads, air pressures, temperatures, engine
performance, and other important test and research parameters during
each flight. Data would be automatically transmitted to the Dryden
mission control center and monitored during flight by project engineers
and other members of the test team.
A spin recovery system built into the test aircraft
would allow the vehicle to be flown to its maximum angle of attack and
as slow as its stall speed. The system will be used to deploy a
parachute if the vehicle begins an uncontrollable descent, such as an
unrecoverable spin. The parachute attach line would be cut, separating
the vehicle from the canopy as soon as stabilized flight could be
resumed.
Construction of the BWB-LSV began in early 2000 and
was scheduled for completion in late 2002. Integration and ground
testing of the vehicle was to continue through 2003, followed by the
test flight program. When assembly of the BWB-LSV was completed at the
Langley Research Center, it was to undergo three months of wind tunnel
testing at the Old Dominion University (ODU) Full-Scale Wind Tunnel
Facility in Hampton, Va.
Research in ODU's massive 30 by 60-foot wind tunnel
wwould include operating the engines and the external flight control
surfaces at various air speeds. Data from this research will give
engineers and designers a better understanding of the aerodynamics
associated with the BWB's unique design prior to flight, as well as a
unique opportunity to test the same vehicle on the ground and in flight.
In a joint effort between NASA and Boeing, in June
2004 the flying wing aircraft design began preliminary testing in a
high-pressure, super-cold wind tunnel at NASA Langley. The tunnel -- the
National Transonic Facility -- accurately tests scale models at speeds
and conditions simulating actual flight.
X-48A Flight Test Program
At the conclusion of the wind tunnel research the
Low-Speed Vehicle was to be transferred to Dryden where it will be
readied for its first flight, scheduled [as of 2001] to take place in
2004.
Preflight work at Dryden will include final systems
integration, ground vibration tests to investigate the design's
structural modes, and electromagnetic tests to assure that it can be
remotely operated without causing electronic interference to aircraft
systems. The aircraft will undergo a final combined systems test and
taxi testing prior to the actual flight research.
The flight schedule called for approximately 30 to
50 one-hour flights over a period of a year. Like most flight test and
research programs, the schedule begins with benign operations and
increases in complexity as flight experience is gained.
All flying of the remotely piloted vehicle wwould
be in restricted airspace over the Dryden complex at altitudes up to
10,000 ft.
The flight tests was to use two sets of flight
control laws. One is a basic set that will be used for most of the
research flying, developed jointly by Langley and Dryden. The other set
of flight control laws will help investigate specific research and
high-risk test points. If the reaction of the vehicle is unacceptable
during a high-risk flight, control of the vehicle will revert to the
basic set of control laws. These procedures are designed to ensure safe
flight operations.
X-48B
The X-48B is a smaller eight-and-a-half percent
scale prototype. The X-48B prototypes have been dynamically scaled to
represent a much larger aircraft and are being used to demonstrate that
a blended wing body is as controllable and safe during takeoff,
approach, and landing as a conventional military transport airplane.
Initially it was tested in the Langley Full-Scale Tunnel at NASA's
Langley Research Center in Hampton, VA. Boeing Phantom Works' advanced
research and development unit partnered with NASA and the U.S. Air Force
Research Laboratory (AFRL) at Wright Patterson Air Force Base, Ohio, to
explore and confirm the structural, aerodynamic and operational
advantages of the blended wing body design.
The team produced two high-tech prototypes of the
BWB, built to Boeing specifications by Cranfield Aerospace in England,
for wind tunnel and flight-testing. The Air Force designated the
vehicles as the "X-48B" based on its interest in the design's potential
as a multi-role, long-range, high-capacity military aircraft. X-48B Ship
No. 1 is the wind tunnel test model. In mid-May 2006, the research team
successfully completed 250 hours of wind tunnel tests on the X-48B Ship
No. 1, at the historic Langley Full Scale Wind Tunnel at NASA�s Langley
Research Center, Langley Air Force Base, Va. The prototype was then
shipped to NASA�s Dryden Flight Research Center at Edwards Air Force
Base, Calif., where it would serve as a backup to Ship No. 2, which will
be used for planned remotely piloted flight tests at Edwards. Ship No. 2
had been scheduled to be used in remotely-piloted flight testing at
Dryden.
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