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Re: NOVA problems
"People are doing double back flips to explain away how the rear airfoil,
whose area at least matched and may have exceeded that of the arm wings, was
not
used in a fairly conventional manner with wild and convoluted postures and
poses."
Yes, they certainly are. However, we need to consider what is meant here by
"conventional". The backflips are occurring in an attempt to make the hind
"wings" into airfoils that support weight in a steady glide, in a fixed
position. As best I can tell, this just isn't plausible. The feathers are
unlikely to be used "backwards" as you mentioned, the hind limbs cannot be
substantially sprawled, and the feathers are very unlikely to have oriented
laterally from the tmt as in the C&T version. The large area suggests that the
hind foils had a substantial aerodynamic action, but the morphological
constraints and shape of the effective "tip" on the hind foils mean that they
were probably not classic wings. Instead, there are other, perfectly simple
ways in which such foils can be aerodynamically active and advantageous (one of
which was already mention: redirection of thrust vectors via effects on the air
accelerated by the forewings).
"Yet in their wind tunnel tests they concluded that the bizarre arrangement
with the legs paralleling the tail was
the most effective, even though the foot borne primaries are oriented so that
the trailing edge is acting as the leading edge! Gosh, one would think that if
the legs were being used in such an adsurd manner, at least the development
of the feathers would have been selected for them to be at least oriented in
the proper aerodynamic manner. Duh."
You'd think. Although, just to play devil's advocate, developmental
constraints could limit the orientation of hind foil feathers to those that are
homologous with the forelimb feather arrangment. That said, I would expect
such a constraint to simply prevent the aforementioned bizarre position, rather
than constrain the animal to using the feathers backwards.
Cheers,
--Mike
Michael Habib, M.S.
PhD. Candidate
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280 0181
habib@jhmi.edu