RE: NEW PAPERS and flight stroke

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Jim Cunningham wrote: 

> What I'm trying to ask, is what is the physical mechanism that causes
> this to be the case?  How are the forces produced?  Note that I'm not 
> arguing that this isn't the case.

I could be misreading your question, but my take on it is this: if you want
to impart a force against a fluid, it's better to execute a widest
practicable arc of excursion.  You mentioned the motion of an oar during
rowing.  I'm aware that this motion is NOT analogous to the motion of a wing
during flapping flight.  However, the blade is positioned at the end of the
oar, and this part 'pushes' against the water - far more effectively than a
simple pole (depending upon the blade's orientation).  The long pole
provides the actual movement responsible for steering.  


> >  This is demonstrated by 'flying' frogs with their webbed digits; 
> > they move their hands and feet to help steer them during their fall.
>
> What is the approximate aoa that they use when doing this?

The authors do a better job than I could to explain:

Emerson, S.B. and Koehl, M.A.R. (1990.  The interaction of behavior and
morphological change in the evolution of a novel locomotor type - flying
frogs.  Evolution. 44 (8): 1931-1946.

McCay, M.G. (2001)  Aerodynamic stability and maneuverability of the gliding
frog _Polypedates dennysi_.  Journal of Experimental Biology 204 (16):
2817-2826.

> >  For a flapping flyer (birds) the outer wing is primarily responsible
> > for generating thrust during flight.
>
> Yes, and lift and drag too.

I was under the impression that the *entire* wing (and the inner portion
especially) were responsible for lift-generation.  The majority of thrust is
provided by the outer wing - but I wouldn't have said the same for lift.




Tim