This is an excerpt from EERE Network News, a weekly electronic newsletter.
New Fuel-Efficient Jet Prototype Features Blended-Wing Design
A scale-version prototype of a new fuel-efficient jet design successfully completed its first test flight in late July. Designed through a collaboration of the Boeing Company, the Air Force Research Laboratory, and the National Aeronautics and Space Administration (NASA), the X-48B features a blended-wing body design, a nearly triangular shape in which a rear wing blends smoothly into a wide, flat fuselage. According to NASA, this design provides additional lift with less drag than a traditional cylindrical fuselage, resulting in less fuel consumption at cruising speeds. The design could also allow for more carrying capacity and might also reduce noise.
The aircraft that is currently undergoing flight tests is an 8.5% scale model with a 21-foot wingspan, weighing in at only 500 pounds. The remote-controlled research aircraft reached an altitude of 7,500 feet during its maiden test flight, but has the capability of reaching 10,000 feet. It is currently in a "low speed" configuration that flies at 120 knots, but it may later be reconfigured to test its performance at transonic speeds, that is, just below the speed of sound, which is 661.5 knots. Even though modern airliners fly at about Mach 0.85, or 85% of the speed of sound, the airflow over their wings is typically transonic or supersonic. See the press release from NASA's Dryden Research Center and the discussion of transonic aircraft from NASA's Glenn Research Center.