Photos: The blended-wing design of Boeing's X-48B

This look at the X-48B reveals as much about the wind tunnel itself as it does about the aircraft. The test section of the Langley tunnel is roughly 30 feet high by 60 feet wide. A pair of 4,000-horsepower electric motors drives the 35.5-foot wood propellers from a starting speed of approximately 80 revolutions per minute to a maximum of 210rpm. (For specialized purposes, they can be set as low as about 20rpm.)