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Re: New bird /pterosaur flight paper in PLoS ONE



Since when is the lift found in "cloud streets" not thermally generated? Or 
"microlift", as I understand the term when used in ultralight flight. And since 
when do sailplanes engage in albatross-style dynamic soaring? 

The paper (as I skimmed it) simply measured and scaled (in vivo) flap 
frequencies of albatrosses and similarly flight-styled birds using empirical 
methods, and concluded that the larger ptero's could not flap fast enough hack 
that type of lifestyle, assuming that fluid conditions were the same in their 
time as present day. 

One can question the assumption that the birds studied represent a minimum 
threshold of 'flapping competence', or even the concept of size-related 
scaling, but they did in fact point out that they were not ruling out 
thermalling. 

"...since neither those sailplanes nor pterosaurs are dependent upon thermal 
lift. Any paper that assumes that they are is deeply flawed." That follows from 
their conclusion. It was NOT an a priori assumption.

I do not know if their conclusions are valid, but I certainly applaud the 
empirical approach...

--- On Wed, 4/29/09, jrc <jrccea@bellsouth.net> wrote:

> From: jrc <jrccea@bellsouth.net>
> Subject: Re: New bird /pterosaur flight paper in PLoS ONE
> To: "don ohmes" <d_ohmes@yahoo.com>
> Cc: dinosaur@usc.edu
> Date: Wednesday, April 29, 2009, 7:13 PM
> I WAS drawing a parallel between pterosaurs and similarly
> sized and configured sailplanes.  It just doesn't have
> anything much to do with thermal lift, since neither those
> sailplanes nor pterosaurs are dependent upon thermal lift. 
> Any paper that assumes that they are is deeply flawed.
> Quetzalcoatlus was as capable as an albatross -- Quetz's
> wings were more capable, accomodating the penalty of the
> long neck and large head.  I've not looked in depth at
> Hatzegopteryx, but would expect similar performance from it.
> JimC
> 
> ----- Original Message ----- From: "don ohmes"
> <d_ohmes@yahoo.com>
> To: "jrc" <jrccea@bellsouth.net>
> Sent: Wednesday, April 29, 2009 4:56 PM
> Subject: Re: New bird /pterosaur flight paper in PLoS ONE
> 
> 
> > 
> > Actually, I jumped to the conclusion that you were
> drawing a parallel between sailplanes and pterosaurs
> relative to the central point of the paper under discussion.
> So sorry...
> > 
> > 
> > --- On Wed, 4/29/09, jrc <jrccea@bellsouth.net>
> wrote:
> > 
> >> From: jrc <jrccea@bellsouth.net>
> >> Subject: Re: New bird /pterosaur flight paper in
> PLoS ONE
> >> To: d_ohmes@yahoo.com
> >> Cc: dinosaur@usc.edu
> >> Date: Wednesday, April 29, 2009, 6:51 PM
> >> P.S.  Note that I said nothing below that implied
> that those
> >> traveling sailplanes were using thermal lift.  For
> >> traveling, cloud streets and microlift are far
> more
> >> effective.  I believe you may have jumped to a
> conclusion
> >> that sailplanes only fly by making use of thermal
> lift.
> >> JimC
> >> ----- Original Message ----- From: "don
> ohmes"
> >> <d_ohmes@yahoo.com>
> >> To: <dinosaur@usc.edu>
> >> Sent: Wednesday, April 29, 2009 4:03 PM
> >> Subject: Re: New bird /pterosaur flight paper in
> PLoS ONE
> >> 
> >> 
> >> >
> >> >
> >> > --- On Wed, 4/29/09, jrc
> <jrccea@bellsouth.net>
> >> wrote:
> >> >
> >> >> Note that sailplanes with wingspans, wing
> areas,
> >> aspect
> >> >> ratios, and gross weights similar to
> those of the
> >> largest
> >> >> pterosaurs are repeatedly capable of
> soaring
> >> non-stop for
> >> >> hundreds of kilometers on an average day,
> and they
> >> don't
> >> >> have the ability to flap at all.
> >> >
> >> > Actually, they cover that -- "The
> present study
> >> does not deny the possibility that they (the large
> >> pterosaurs) might rely on warmed rising air of
> >> thermals..."
> >> >
> >> > Don
> >> >
> >> >
> >> >
> >