Mechanical 'Skin' Reduces Airplane Drag

May 1, 2008 -- A new "skin" that changes shape at the push of a button could reduce the drag forces on an object in motion from 20 to 40 percent.

When applied to ships or airplanes, the active coating could make them faster and more fuel efficient, saving millions of dollars each year.

"The portion of airline direct operating costs attributable to fuel has increased from some 15 percent to 35 percent, heading to 50 percent-plus," said Dennis Bushnell, chief scientist at the NASA Langley Research Center, who was not involved in the research.

"Aircraft drag reduction is becoming, again, a serious research issue," he added.

As air or water flows over an object, it creates tiny pockets of turbulence that slow the object down.

Even the flattest surfaces, the creation of which is a traditional engineering goal, suffer spontaneous turbulence.

In recent years, designers have roughed things up, adding tiny, immobile riblets to skins.

The riblets break apart the random formation of turbulent pockets and create specific, controlled areas of turbulence that engineers can use to their advantage.