Scientists from Boeing Phantom Works, the National Aeronautics and Space Administration (NASA), and AFRL are testing a new aircraft with the potential to realize up to 30% better fuel efficiency because of its unique "flying-wing" shape. The prototype blended wing body, or BWB, aircraft is a modified, triangular-shaped aircraft configuration with 20 control surfaces along its trailing edge. Researchers believe the BWB configuration will produce better fuel efficiency because a greater portion of the aircraft is involved in producing lift. The additional lift stems from the replacement of the conventional tube-shaped aircraft fuselage with the more aerodynamically efficient wing centerbody.
Scientists from the three groups are collaborating on the unmanned research aircraft to explore and validate the structural, aerodynamic, and operational advantages of the BWB concept. According to Mr. Dan Vicroy, senior NASA research engineer, "One big difference between this airplane and the traditional tube-and-wing aircraft is that instead of a conventional tail, the BWB relies solely on multiple control surfaces on the wing for stability and control."
The Air Force (AF) is interested in the technology for military applications and has designated two high-fidelity, 21 ft wingspan prototypes as X-48B test vehicles. "The BWB technology can cost-effectively fill many AF roles," states Second Lieutenant Scott Vanhoogen, AFRL's X-48B program manager. "In an era of rising fuel costs and economic constraints, a more efficient plane that can perform the same missions as current aircraft provides greater operational flexibility. We are very interested in the upcoming flight tests."
Constructed primarily of advanced lightweight composite materials, the two prototypes each weigh about 400 lbs and are powered by three turbojet engines. The vehicles—both built by the United Kingdom's Cranfield Aerospace according to Boeing's specifications—will be capable of lowspeed (138 mph), low-altitude (10,000 ft) test flights.
The research team successfully completed 250 hours of wind tunnel tests on X-48B Ship No. 1 in the fullscale wind tunnel at NASA's Langley Research Center, Langley Air Force Base (AFB), Virginia (see figure). The team then shipped the first prototype vehicle to NASA's Dryden Flight Research Center, Edwards AFB, California. There it will serve as a backup to X-48B Ship No. 2, which will be used for remotely piloted flight tests. The team geared both test phases towards learning more about the low-speed flight-control characteristics of the BWB concept. As Mr. Norm Princen, Boeing Phantom Works chief engineer for the X-48B program, explains, "The X-48B prototypes have been dynamically scaled to represent a much larger aircraft and are being used to demonstrate that a BWB is as controllable and safe during takeoff, approach, and landing as a conventional military transport airplane."
Mr. Joseph Lusczek, technical director of aerospace systems design and analysis at Air Force Materiel Command's Aeronautical Systems Center (ASC), has been following Boeing's BWB development since 1995. In Mr. Lusczek's opinion, the BWB concept has considerable potential and could have application to many future AF systems. "The efficient design would have applicability to transport, tanker, bomber, surveillance, and other types of aircraft requiring long range and large payload capacities," he elaborates. "The concept could also have application to small unmanned vehicles, as demonstrated by the test prototypes." In fact, ASC has already performed aircraft design studies using the BWB concept for potential tanker, cargo, and longrange strike missions. Furthermore, Mr. Lusczek indicates that "Boeing has conducted studies showing a BWB aircraft's weight would be about 80% the gross weight of a conventional aircraft designed to perform the same mission. The aerodynamic efficiency of the concept—which uniformly distributes lift over the total span of the aircraft, including its lifting fuselage— requires about 30% less fuel to accomplish the mission."
The Boeing, NASA, and AFRL cooperative agreement on the X-48B program culminates years of BWB research performed by NASA and Boeing. "Those associated with the evolution of the concept are to be commended for their innovation, engineering excellence, and foresight," Mr. Lusczek affirms. "It has been rewarding to watch this revolutionary concept develop. It is a new plateau in airplane design and has the potential to be the shape of the future for aircraft."
Ms. Larine Barr, of the Air Force Research Laboratory's Public Affairs Office, wrote this article. For more information, visit http://www.afrl.af.mil/techconn_index.asp. Reference document HQ-H-06-07.
Air Force Research Laboratory Technology Horizons Magazine
This article first appeared in the December, 2006 issue of Air Force Research Laboratory Technology Horizons Magazine.
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