At 11:06 AM 27/03/2008, you wrote:
>On 27/3/08 1:27 AM, "Michael Derry" <[EMAIL PROTECTED]> wrote:
>John Roake: His reply hereunder:
>
>THIS FROM THE JANUARY ISSUE OF GLIDING INTERNATIONAL
>
>
>SHARK SKIN RESEARCH COULD REDUCE SAILPLANE DRAG BY 30 PERCENT It
>may seem obvious that the surface of an airplane should be as smooth
>as possible to minimize aerodynamic drag, but that's not really the
>case. A bit of roughness can break up the boundary layer and improve
>efficiency. Sharks, with skin formed of rough scales called
>denticles, can slip through the water at speeds of up to 60 mph with
>minimal drag. This week, The Lindbergh Foundation awarded a grant to
>Dr. Amy Lang, at the University of Alabama, to study whether the
>surface texture on the skin of fast-swimming sharks, capable of
>bristling their scales when in pursuit of prey, could be mimicked
>and used to reduce the drag on sailplanes. "If we can successfully
>show there is a significant effect, future applications to reduce
>drag of sailplanes and underwater vehicles could be possible," said
>Lang. The technology has the potential to increase aerodynamic
>efficiency up to 30 percent, with savings of billions of dollars and
>substantial reductions in aircraft fuel burn and emissions. Dr. Lang
>will perform water-tunnel experiments to measure the flow over and
>within a bristled sharkskin model (2 cm size scales), which achieves
>similarity with real sharkskin (0.2 mm size scales) by a
>corresponding scale down in velocity of the experiments. She will
>also obtain drag measurements over a sharkskin model in a Couette
>flow facility containing high-viscosity oil. Her work is also
>supported by the National Science Foundation.
>
>
>
>JOHN, EDITOR, GLIDING INTERNATIONAL
>
AFAIK this has all been done long ago. Either the Lindberg Foundation
thinks this is a new angle on it or they are unaware of the previous work.
Mike
Borgelt Instruments - manufacturers of quality soaring instruments
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