While the design has yet to catch on with civilian air travellers (focus groups hate amphitheater-style seating), the Blended Wing Body aircraft holds great promise for military operations. To better study this innovative design without sinking untold extra millions into R&D, NASA built the next best thing — a 1:8.5 scale RC demonstrator.
The X-48B isn't a run-of-the-mill RC plane, mind you. Designed by Boeing Phantom Works in conjunction with the Air Force Research Laboratory, the X-48 has a 6m wingspan that accurately mimics the structural, aerodynamic and operational features of the Blended Wing Body concept. A trio of JetCat P200 turbojet engines propel the 230kg model up to 220km/h with a 3000m operational ceiling and a 40-minute flight duration.
The Blended Wind Body design — understandably unpopular with commercial carriers — does have several advantages over conventional aircraft, especially as a multi-role, long-range, high-capacity military transport. Flattening the body of the aircraft to act as part of the wing generates less drag, which translates into a longer operational range, better fuel economy, less noise, a larger payload capacity, and lower manufacturing and maintenance costs.
The X-48 Concept was first concocted in the late 1990s by engineers at McDonnell Douglas. After McDonnell Douglas merged with Boeing, the firm worked with the NASA Langley Research Center to create a precursor to the X-48 program, a 5m wide propeller-driven drone that flew briefly in 1997. However, by the time the X-48A, a 11m BWB model got off the ground in 2004, Boeing had effectively cancelled the project.
Typically, when R&D projects like this are cancelled, they stay cancelled. However, by 2007, Boeing was back hard at work on the X-48B — a smaller, more robust iteration of the series design. Two such 48Bs were built in the UK by Cranfield Aerospace. They first flew in July of that year at the NASA Dryden testing facility, reaching 2286 metres during the 30-minute flight. "Earlier wind-tunnel testing and the upcoming flight testing are focused on learning more about the BWB's low-speed flight-control characteristics, especially during takeoffs and landings," Norman Princen, Boeing's chief engineer for the project, said. "Knowing how accurately our models predict these characteristics is an important step in the further development of this concept." Ninety-two test flights and nearly two years later, Boeing and NASA concluded the X-48B's initial testing in March of 2010.
Since then, Boeing has been working to further upgrade the X-48's capabilities. Though built from an X-48B chassis, the new X-48C is even more quiet than its predecessor thanks to a Hybrid Wing Body (HWB) aircraft design. Other changes include relocating the upturned winglets, from out the wingtips in towards the engines, to increase stability. Also, Boeing replaced the trio of 230kg thrust engines with a pair of smaller 40kg thrusters. The model C made its successful maiden voyage this past Tuesday above Edwards Air Force Base in California's Mojave Desert. [Defense Systems - Wikipedia - NASA - Boeing]