A small-scale NASA model of a Boeing flying wing concept has just finished testing at the U.S. Air Force's Arnold Engineering Development Center (AEDC) in Tennessee.
Engineers and technicians tested a two-percent model of a blended wing body (BWB) aircraft in the center's 16-foot transonic wind tunnel (16T). The primary objective was to add to an aerodynamic database of flight characteristics started when the same model underwent tests at the National Transonic Facility at NASA's Langley Research Center in Hampton, Va.
"The testing at AEDC was conducted to collect some of the higher Mach number data points for this blended wing body configuration at non-cruise speeds," said Dan Vicroy, a NASA Langley research engineer. "We subjected the model to some subsonic flows, but mainly this test covered transonic speeds."
Testing in 16T began with the model of the BWB in a "clean-wing" configuration, minus engine nacelles and winglets, according to NASA research engineer Melissa Carter.
"We always start off with a clean wing," she explained. "Later we added the winglets, then the pylons, engines, all in stages. What we were looking for was a buildup, a drag cost. We wanted to determine what these components will add to the drag. We were looking for both the cumulative and incremental effects on drag for this aircraft."
The cooperative NASA/Air Force/Boeing test was sponsored by the Air Force Research Laboratory (AFRL). AEDC Air Force Project Manager 1st Lt. Ezra Caplan said the coordination between AEDC, NASA and the AFRL was critical in the success of the project.
"This was a team effort in every sense of the word - in both planning and test operations," said Caplan. "We were operating on a limited schedule and AFRL and NASA were operating under a tight budget."
A BWB prototype designated the X-48B by the Air Force, soon will begin flight testing at NASA's Dryden Flight Research Center at Edwards Air Force Base in California. The unmanned X-48B, which has a 21-foot (6.4 m) wingspan, is the result of collaboration between Boeing Phantom Works, NASA and AFRL.
According to NASA engineers a BWB offers greater structural, aerodynamic and operating efficiencies than the more conventional tube-and-wing design. In essence, the aircraft's design increases lift and reduces the overall drag during flight.
The Air Force is looking at the blended wing body concept for a variety of potential applications, including as a cargo/personnel transport and a refueling tanker.
According to Dennis Carter, aerospace engineer for the AFRL's Air Vehicles Directorate, one use for the BWB would be a military tanker with two refueling points and automated refueling capabilities. "A blended wing body tanker would be able to accommodate simultaneous air-to-air refueling of multiple conventional aircraft or UAVs," he said.
Fuel for the BWB could be carried in wing tanks, leaving room in the body for pallets and troops. In addition to fuel efficiency engineers say the blended wing body design would offer significant noise reduction.
NASA Langley Research Center