News

Professor's wing design change may save fuel

By Jon Van
Chicago Tribune
June 19, 2004

With fuel prices soaring and airlines struggling to make money, an engineering professor's discovery may attract some interest.

Warren Phillips, a professor of mechanical and aerospace engineering at Utah State University, believes he's found a way to cut airplane fuel use and potentially save millions.

Phillips has found that induced drag on the airplane--the downward pressure caused by air moving past the trailing edge of the wing--can be significantly reduced with some relatively simple changes in wing design.

Specifically, Phillips advocates replacing the pilot-controlled airfoils at the wings' edge, called ailerons, with more flexible devices called twisterons.

Ailerons are used by pilots to control rolling movements of the airplane, and Phillips' proposed twisterons would do that as well.

The twisterons, however, would also constantly adjust their shape to minimize induced drag.

This would be accomplished through sensors that keep track of the airplane's speed, acceleration and weight and the air density. Using this input, a computer would continually adjust the twisteron's shape to reduce drag.

Phillips and his colleagues have built a robotic plane equipped with twisterons to demonstrate how his system works, and his university has applied for a patent. His hope is that a company will use the technology to retrofit existing airplanes.

Phillips' innovation may spring in part from his hobby as a hang-glider pilot.

"Hang gliding gives you a real feel for flight," Phillips said. "I have flown airplanes, and when you're flying an airplane, you're driving a machine. When you're flying a hang glider, it's literally like being a bird. You feel the air, and your thoughts control the glider. It gives a real feel for lift, drag and how the air interacts with the wings, much more so than you get from flying a machine."

But it wasn't just intuition that led Phillips to his idea for twisterons. He also spent a lot of time revisiting the original mathematics worked out almost a century ago by Ludwig Prandtl, the German scientist known as the father of modern fluid mechanics.

Phillips' solution to the relevant differential equations suggested to him that twisterons would reduce drag with less effort than any solutions suggested by Prandtl's earlier work.

It's not that Prandtl was wrong, Phillips said, but rather that when he did his work, he didn't have access to today's technology, so something like a twisteron wasn't possible.

Phillips said the greatest cost associated with installing his twisteron technology may be the design and engineering work needed to be certified as safe by the Federal Aviation Administration. For that reason, he said, the technology will probably first be applied to robotic planes.

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