21 January 2007

Bats flying battily

It seems that bats know more than they should about flying, able to routinely pull stunts which take high-speed video cameras & wake analyses to untangle.

The results suggest the possibility that a novel lift-generating mechanism may be at work in bats & point to the highly maneuverable mammals as a model for tiny flying machines.

...and here comes the science...

“Bats have unique capabilities,” says Breuer, “but the goal is not to build something that looks like a bat. We want to understand bat flight & be able to incorporate some of the features of bat flight into an engineered vehicle.”

...with some interesting observations about evolution...

“Gliding has evolved in mammals seven times. That tells us that it’s really easy for an animal with skin to evolve into a glider, but going from a square gliding wing to a long, skinny flapping wing has not happened seven times. It might have happened once. And now it doesn’t look like bats have any relationship to these gliding things.”

...& also this interesting observation from the wake-tracking gear...

The detail of this first reconstruction is limited by the rate at which the laser setup can collect data, but it is clear that the aerodynamics of the bat’s up stroke are quite different than what is seen in birds and insects. During the down stroke, the vortex — which generates much of the lift in flapping-wing flight — closely tracks the animal’s wingtip. In the up stroke, the vortex seems to be shed from another location entirely — perhaps the animal’s wrist joint.

...& here I was, thinking of bats as merely flappy leathery critters that make funny noises at night...

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