Re: Gliders to Fliers? (Was Re: Ruben Strikes Back)

["James R. Cunningham" <jrccea@bellsouth.net>]

For visualization purposes only, think of the arm as a cylindrical cross
section held perpendicular to the airflow.  Then fair it with feathers.  The
drag of the faired shape will drop by up to 96%.  Another way to say it is
that a faired shape up to 25 inches thick (and with a chord of perhaps 75-100
inches) can have the same drag as an unfaired circular cylinder 1 inch in
diameter.  Developing feathers on the arms could reduce drag even while
allowing the arms to grow larger.  Or, if the feathered arms were held close
to the body, could substantially reduce total profile drag of the wing/body
combination.
Jim

Larry Febo wrote:

> Which brings to mind the dilemma...if theropods were developing bipedality
> in order to run faster, why would they develope feathers on the arms, or
> larger arms for that matter. It seems this would tend to slow them down!