Re: What is biomechanics? (or, The Truth About Flying Snakes - Was: Re: science and philosophy)

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

Jaime A. Headden wrote:

>  It is a feather in action that does
> anything, and not just a single feather, but a arrangement.

What about the tip feathers in birds of intermediate aspect ratio, where 
feathers act individually to increase the effective aspect ratio, modulate the 
tip vortex, and provide thrust?

>  And this is a parachuting animal, right?  I mean, just because it's called a 
> flying snake, surely
> no-one was seriously suggesting that it moved through the air by lift-based 
> powered flight?

Doesn't that sort of depend upon the shape and path of the vortices above its 
body?

> I do not support *Longisquama* flying by any
> present data. Or even gliding. So far, no study shows what appear to be
> radiating slats could even produce a sustained drag

Is this a presumption about type of lift produced, if any?

> <And paragliders do the same thing.  It's not gliding in the sense of a
> glider 'plane, or a soaring bird,

But is, in the sense of a gliding Concorde or other aircraft with low-aspect 
ratio wing.

> but surely most animals that get called
> 'gliders' - flying frogs, flying squirrels, sugargliders, for example -
> are really parachutists of some description (with varying ability to control
> their descent)?

I wouldn't say 'surely', unless I had looked at the shape of the vortices 
produced during their flight.  Has anyone done that yet for all three of these 
species?

>  The only 'glider' that might be closer to a glider 'plane
> that I can think of offhand is _Draco_.>
>
>   I know of some references that have drawn differences in animals that
> glad versus parachute, and the snake and frog are both considered
> parachuters,

Gliding snakes remind me a lot of the fuselage lift mechanisms produced by 
dirigibles.  Do they you?

> The distinction has been to support with anatomy a direction-based
> definition, above or below 45 degrees.

I've not ever looked to see -- is this a distinction favored by biologists, or 
defined by aerodynamicists?  What specific and sudden change in airflow occurs 
at a descent slope of 100%?

All the best,

Jim