Wind Tunnel's Swan Song

A historic wind tunnel at NASA's Langley Research Center in Hampton, Va., has been pressed into service one last time to help test the prototype of a new, more fuel-efficient, quieter aircraft design. Boeing Research & Technology, Huntington Beach, Calif., recently partnered with NASA's Aeronautics Research Mission Directorate and the U.S. Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio, to explore and validate the structural, aerodynamic and operational advantages of an advanced concept called the blended wing body or BWB.

"We have one version of the 21-foot (6.4 m) wingspan BWB prototype, called the X-48B, being flight tested at NASA's Dryden Flight Research Center, in Edwards, Calif.," said Dan Vicroy, senior research engineer at NASA Langley. "The other one we just tested in the Langley Full-Scale Tunnel is the X-48C. It's been modified to make it even quieter. We're assessing the aerodynamic effects of those modifications." Those changes include reducing the number of engines from three to two and the installation of vertical fins to shield the engine noise.

Cranfield Aerospace Ltd. in England built both ground-breaking aircraft scale models to Boeing's specifications. Made primarily of advanced lightweight composite materials, the models weigh about 500 pounds (227 kg) each. They are powered by turbojet engines and can fly up to 138 miles per hour (222 kph) and 10,000 feet (3,048 m) in altitude during flight-testing. The Air Force is interested in the plane's potential as a multi-role, long-range, high-capacity military aircraft.

In 2006, preliminary tests helped engineers determine how the X-48B would perform during remotely piloted flight tests. Blended wing body designs are different from traditional tube-and-wing aircraft in that the tube and wings are blended for lower drag and better lift, and they rely primarily on multiple control surfaces on the wing for stability and control.

"It was actually a big thrill for me to be back at the Langley Full-Scale Tunnel," said Dharmendra Patel, project manager for the X-48C at Boeing Research & Technology. "I think it's a big privilege that we were the last test here, that we get to be part of the history of the tunnel. But it is a little bittersweet that the facility will be closed down."

Langley decommissioned the tunnel in 1995, and then leased it to Old Dominion University in Norfolk, Va., for research and student engineering training. That lease was up this summer and the tunnel is scheduled for demolition because of its lack of national strategic importance, limited testing capability, deteriorating condition and the environmental liability associated with the materials used in its construction.