Bats generate a measurably distinct aerodynamic footprint to achieve =

lift and maneuverability, quite unlike birds and contrary to many of =

the assumptions that aerodynamicists have used to model animal flight, =

according to University of Southern California aerospace engineer =

Geoffrey Spedding.

        http://www.physorg.com/news98026462.html

They note that bats twist their wings in a hitherto unreported manner =

which increases lift during the upstroke.

Well worth reading for any flight enthusiasts.



        Russell

_________________________________



... bat flight is quite different from bird flight, particularly at =

very small scales.
... Bats ... generate very different wakes ...
The tell-tale tracks in the airflow caused by the wing beat have a =

very different pattern for bats, and this difference can be traced to =

the peculiar upstroke," ... That, in turn, is likely caused by the =

collapsible membrane of the bat=92s wing, which needs to maintain some =

degree of tension.

His research group=92s findings are presented in an article titled "Bat =

Flight Generates Complex Aerodynamic Tracks." Coauthors included A. =

Hedenstr=F6m, L. C. Johansson and M. Wolf of Lund University, Sweden; R. =

von Busse of the University of Munich, Germany; and Y. Winter at =

Bielefeld University in Germany.

"Instead of feathers projecting back from lightweight, fused arm and =

hand bones, bats have flexible, elastic membranes that stretch between =

specially extended, slender bones of the hand," Spedding said. "The =

bones and wing membrane both change shape with every wing beat, =

flexing in response to the balance between forces applied by the =

muscles and competing forces due to the air motion around them. "

etc

-- =

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