RE: NEW PAPERS and flight stroke

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Jim Cunningham wrote:

>What I think I'm hearing implies that you are saying the major forces 
> are produced by the wings moving pretty much transversely to the fluid 
> flow (like the oars when rowing a boat), and I know you couldn't 
> possibly mean that.  Could you elaborate please, so I can get a
> better handle on what you are saying?

The thrust (so to speak) of what I was saying was that to maximize drag or
thrust for a parachuting or flying animal, the drag- or thrust-generating
surfaces are best located at the end of moveable appendages (far from the
body) rather than close to the body.  For a non-flapping, non-flying animal
that wants to maneuver itself through the air during descent, the
drag-generating devices are located distally.  This is demonstrated by
'flying' frogs with their webbed digits; they move their hands and feet to
help steer them during their fall.  For a flapping flyer (birds) the outer
wing is primarily responsible for generating thrust during flight.    



Tim