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Re: Dinosaur Fore Limb Posture & Evolution of Avian Flapping Flight Stroke
Eike, it is cool, but it might be more useful to use the reduced frequency
for your purpose rather than the Strouhal number, since high values of
reduced frequency infer that flow geometry is changing rapidly and that
unsteady aerodynamic effects would have to be accounted for (rapidly
changing flow geometry will change the stall speed). It is difficult to
determine Strouhal number in the field, because it is hard to photograph an
accurate wingtip amplitude. The reduced frequency is determined similarly
to the Strouhal number, but uses the mean chord (wing area/wingspan) as a
reference length instead of the flapping amplitude. The reduced frequency
is easier to field measure.
----- Original Message -----
From: "evelyn sobielski" <firstname.lastname@example.org>
More fundamental to the origin of the avian flapping flight-stroke is the
question of how a symmetrical forelimb posture â required for gliding and
flapping flight â evolved from an alternating forelimb motion, evident in
all extant bipeds when running except birds."
Cool! One might try and glean some angles to estimate A from here
http://www.app.pan.pl/article/item/app51-305.html?pdf=39 and see what
minimum f would cause U to exceed stall speed in different taxa.