The X-48C is a scale model of a heavy-lift, subsonic aircraft that possibly could be developed for military applications. Boeing and NASA believe the BWB concept offers the potential over the long-term of significantly greater fuel efficiency and reduced noise. NASA photo. Click to enlarge.

The X-48C is a scale model of a heavy-lift, subsonic vehicle that forgoes the conventional tube-and-wing airplane design in favor of a triangular aircraft that effectively merges the vehicle’s wing and body. Boeing and NASA believe the BWB concept offers the potential over the long-term of significantly greater fuel efficiency and reduced noise.

Working with NASA, we are very pleased to enter into the next flight-test phase of our work to explore and validate the aerodynamic characteristics and efficiencies of the Blended Wing Body concept. In our earlier flight testing of the X-48B, we proved that a BWB aircraft can be controlled as effectively as a conventional tube-and-wing aircraft during takeoffs and landings and other low-speed segments of the flight regime. With the X-48C, we will be evaluating the impact of noise shielding concepts on low-speed flight characteristics.

— Bob Liebeck, a Boeing Senior Technical Fellow and the company’s BWB program manager

The X-48C is a modified version of the X-48B aircraft, which flew 92 times at NASA Dryden between 2007 and 2010. The X-48C retains most dimensions of the B model, with a wingspan just longer than 20 feet, and a weight of about 500 pounds. The aircraft has an estimated top speed of about 140 mph, and a maximum altitude of 10,000 feet.

The X-48C is configured with two 89-pound thrust turbojet engines, instead of three 50-pound thrust engines on the B-model; and wingtip winglets have been relocated inboard next to the engines on the C-model, effectively turning them into twin tails. The aft deck also was extended about 2 feet at the rear.

The modified test vehicle was designed by Boeing and built by Cranfield Aerospace Ltd., in the United Kingdom, in accordance with Boeing requirements.

Engineers from Boeing Research & Technology, the company’s central research, technology and innovation organization, will be working closely with NASA engineers during flight tests of the X-48C, which are expected to continue throughout 2012. As handling qualities of the X-48C will be different than those of the X-48B, the project team developed flight control software modifications, including flight control limiters to keep the airplane flying within a safe flight envelope.

With a 21-foot wingspan, the 500-pound aircraft is an 8.5% scale model of a heavy-lift, subsonic airplane with a 240-foot wingspan that possibly could be developed in the next 15 to 20 years for military applications such as aerial refueling and cargo missions. The X-48C has an estimated top speed of about 140 miles per hour, with a maximum altitude of 10,000 feet. The X-48C project team consists of Boeing, NASA, Cranfield Aerospace, and the US Air Force Research Laboratory.

Boeing and NASA’s Aeronautics Research Mission Directorate are funding X-48 technology demonstration research. The effort supports NASA’s Environmentally Responsible Aviation project, which has goals to reduce fuel burn, emissions and noise of future aircraft.