Technicians have installed a five-percent scale model of a blended wing body in the Langley Full-Scale Tunnel at NASA's Langley Research Center in Hampton, Va. During tests in the tunnel's huge 30X60 foot test section, pilots "flew" the 12-foot wingspan, 80-pound model. It stayed aloft in the tunnel's wind stream constrained only by a tether cable. The flying wing is the biggest model ever to be free flight tested in the Full-Scale Tunnel.

"We want to understand the edge of the envelope flight characteristics of the blended wing body," said Dan Vicroy, blended wing body flight dynamics principal investigator. "We're comfortable with the flight characteristics of conventional tube with wings airplanes, but we don't have much experience with flying wings."

NASA is working with Boeing Phantom Works, Long Beach, Calif., on this advanced, more fuel-efficient and environmentally friendly airplane concept. Researchers say a blended wing body could be useful as a multi-role aircraft for the military, including functioning as a tanker, cargo or transport plane.

But much testing needs to be done before the blended wing body could be safely introduced as a transport aircraft. For instance the blended wing body doesn't have a conventional airplane tail, used to control pitch (up and down) and yaw (side to side) motions. Instead it uses a combination of control surfaces on the trailing edge of the wing to control and maneuver the airplane. The free flight tests will help assess the best combination of control surfaces and control limits.

Other questions also need to be answered about the blended wing body configuration. "One is – how do you build a lightweight structure that can be pressurized," said Vicroy. "It's easy to pressurize a tube, but not as easy to pressurize a non-cylindrical shape."

Even building the blended wing body model was a challenge. For this test the model had to be dynamically scaled, which means it had to have the same scaled shape as the real plane as well as the scaled weight and inertia characteristics of roll, pitch and yaw. This required the model to be very lightweight for its size. It was built out of graphite composite material similar to that used to build Formula 1 racecars.

Owned by NASA Langley and operated by Old Dominion University in Norfolk, Va. The Langley Full-Scale Tunnel was completed in 1931. It has been used to test everything from World War II fighters, to submarines, to the Mercury capsule to concepts for a supersonic transport and now a flying wing.

The research is part of the Fundamental Aeronautics Program in NASA's Aeronautics Research Mission Directorate. The program's goal is to advance breakthrough aerospace technologies.

December 4, 2005

MORE (Aviation Future)