With a 21-foot wingspan, the 500-pound X-48 airplanes are 8.5 percent scale models of a heavy-lift, subsonic airplane with a 240-foot wingspan that the Boeing Phantom Works organization believes could be developed in the next 15 to 20 years for military cargo applications. Because of the X-48B’s efficient aerodynamics, Boeing and NASA researchers believe that the BWB (Blended Wing Body) configuration offers the potential for reduced fuel burn over conventional similar-sized tube-and-wing transports flying the same mission.