Re: Archie a non-flyer?

[Michael Habib <mhabib5@jhmi.edu>]

> Surely. But if it was an *indirect* result of increased drag the
> latter could be a target for selection.

I'm sure that LEV production is under selection, but it's not dependent 
on total drag, per se, so I wouldn't consider that as an example of 
direct selection for increased drag.  LEV's are often most important at 
high lift coefficients, at which point drag coefficients also tend to 
be high, but that's not the same as selection for high drag itself.

> > A symmetric feather can be built to resist the loads just as well, 
> > but at the
> > cost of being more robust, and thus more massive.  Therefore, an 
> > asymmetric
> > feather is structurally advantageous in terms of material 
> > distribution.
>
> How much weight it could reduce?

Depends on the size of the animal, planform of the wing, and some 
details of feather shape itself.  Suffice it to say the weight 
reduction could add up quickly.  The feathers of a bird can outweigh 
its skeleton, which is saying something because the skeletons are not 
as light as often perceived.  I can do some rough calculations for 
weight saving in a fairly generalized bird - I suspect it's in the 
10-15% range overall, but take that with a big grain of salt until I 
actually run some numbers (Jim may have done so already).

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