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Re: Colin Pennycuick & dinosaur flight



Stephan Pickering wrote:
> And...I recommend Colin's updated Flight
> for Windows, downloadable at
> <http://detritus.inhs.uiuc.edu/wes/pennycuick.html>

This may not be quite the latest version of the program.  The program,
by the way, is absolutely superb.

> Colin points, in his various papers, that large size
> of an animal will cause the researcher, perhaps
> unconsciously, to overemphasize aspects of anatomical
> biomechanics (Colin in a private communication to me
> terms this the TV factor).  A wing span of a pterosaur
> on Walking with Dinosaurs, e.g., may appear  large --
> but one is to remember their fingers were not straight
> while flying,

This is quite true.  Q northropi, for example is usually credited with a
36 foot wingspan, and though the extrapolated bone lengths (a lot of the
wing is missing) add up to well over 36 feet, it is only when about
0.4-0.5 seconds into a downbeat that the wingspan actually approaches 36
feet.  In most of the rest of the wingbeat, particularly during the
upstroke, the span is well under 36 feet.  Since Quetz has a substantial
ventral bend near the outer end of MCIV, bending stress due to lifting
loads will actually increase the wingspan slightly rather than
decreasing it, but not by all that much.


> but bending under stress (looking
> closely at segments now, one sees the FrameStore
> animators were careful with with this; pterosaurs did
> not fly, with outstretched arms, like Batman).

Very true.  They didn't.

> Colin's 1988 paper on pterosaur flight could be updated with
> new specimens, and shared on this forum.

I've privately encouraged him to do that and really wish he would. 
Colin has a remarkable ability to explain flight mechanics in ways that
make it crystal clear.  He is a remarkable man.  He's tried to talk me
into switching to bird flight since there is so much more material
available to work with, but I'm totally hooked on pterosaur flight.

> A second aspect of inferring flight capabilities of
> extinct taxa, even living taxa, is to have some idea
> of environmental data, specifically air density and
> gravity strength (I would also add temperature),

When you specify air density as opposed to pressure, you have
automatically taken the temperature into account.  The easiest way to
treat this is to just make air density one of your variables when you do
your calculations.  That said, since pterosaurs could launch and fly
just fine in today's atmosphere, most of the time I use today's standard
atmosphere in my calculations. 

> and it is possible that, during the Mesozoic, surface air
> density was of a higher exponent.Computer simulations
> could be developed to explore this, I would think.

They already have been.  And Colin has explored the effect of variations
in gravity too.

All the best,
Jim Cunningham