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Re: Naive WAIR Question



> Date: Fri, 17 Jan 2003 11:30:07 -0800
> From: "James R. Cunningham" <jrccea@bellsouth.net>
>
> > Isn't there also something in the morphology of extant avian
> > feathers that inherently suits them for generating upthrust?  I am
> > no expert, but I seem to recall that the cross-sectional profile
> > of a flight feather is curved in much the same way as the wing
> > itself.  Is this a correct recollection?  If so, then you'd think
> > that those WAIRing dinobirds that were best adapted for WAIRing
> > would be precisely those that were _least_ adapted for flight.
> 
> The feather curvature doesn't affect the slope of the lift curve.
> Only the aoa for zero lift, and to some extent, the drag.  I don't
> see it as a big deal. And it only has those effects when the
> feathers are seperated and the flow is also transverse to the
> feather (roughly parallel to the chord).  Note that hummingbirds
> generate lift on both the 'down' and 'up' strokes by partially
> inverting their wings.

OK.

However, my broader question still stands.  I don't see that
adaptation for WAIR, in which wings are used to produce downthrust,
would pre-adapt an animal for flight, in which they are used to
produce upthrust.  As Jeff's New Scientist article has pointed out
(presumably from the paper -- I don't have access to it so I can't say
for sure), WAIRing birds are performing a fundamentally different
action from flying birds, their wings moving in a plane at 90 degrees
to that of flight.

 _/|_    _______________________________________________________________
/o ) \/  Mike Taylor   <mike@miketaylor.org.uk>   www.miketaylor.org.uk
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