is an important step in the further development of this concept." The X-48B has a wingspan, weighs , and is built from composite materials. It is powered by three small turbojet engines and is expected to fly at up to and reach an altitude of . The X-48B is an 8.5% scaled version of a conceptual span design. Though passenger versions of the X-48B have been proposed, the design has a higher probability of first being used for a military transport. Wind tunnel testing on a wide blended wing body model was completed in September 2005. During April and May 2006, NASA performed wind tunnel tests on X-48B Ship 1 at a facility shared by Langley and Old Dominion University. After the wind tunnel testing, the vehicle was shipped to NASA's Dryden Flight Research Center at Edwards Air Force Base to serve as a backup to X-48B Ship 2 for flight testing. X-48B Ship 2 then conducted ground tests and taxi testing in preparation for flight. In November 2006, ground testing began at Dryden, to validate the aircraft's systems integrity, telemetry and communications links, flight-control software and taxi and takeoff characteristics. The second X-48B was modified into the X-48C starting in 2010 for further flight tests. The X-48C has its vertical stabilizers moved inboard on either side of the engines, and its fuselage extended aft, both to reduce the aircraft's noise profile; it was to be powered by two JetCat turbines, each producing of thrust. The X-48C was instead modified to use two Advanced Micro Turbo (AMT) turbojet engines in 2012. Following flight testing of the X-48C in April 2013, Boeing and NASA announced future plans to develop a larger BWB demonstrator capable of transonic flight. Operational history The X-48B first flew on July 20, 2007, reaching an altitude of 7,500 ft (2,286 m); the flight lasting 31 minutes. The remotely piloted aircraft was successfully stalled for the first time on September 4, 2008, with fixed leading edge slats, a forward center of gravity, and 23-degree angle of attack (2° beyond the maximum coefficient of lift). Stall testing was repeated on September 11 with a NASA pilot at the console. On March 19, 2010, NASA and Boeing successfully completed the initial flight testing phase of the X-48B. Fay Collier, manager of the ERA Project in NASA's Aeronautics Research Mission Directorate commented on the completion of the first phase of testing