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From: friesen@psivax.UUCP (Stanley Friesen)
Newsgroups: net.origins
Subject: Re: On Astronomers and Titanium/Mylar Pterosaurs
Message-ID: <724@psivax.UUCP>
Date: Sat, 14-Sep-85 11:46:20 EDT
Article-I.D.: psivax.724
Posted: Sat Sep 14 11:46:20 1985
Date-Received: Thu, 19-Sep-85 05:48:46 EDT
References: <393@imsvax.UUCP>
Reply-To: friesen@psivax.UUCP (Stanley Friesen)
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 78

In article <393@imsvax.UUCP> ted@imsvax.UUCP (Ted Holden) writes:
>
>               Everybody  who  has  ever  studied  pterosaurs  and done any
>          THINKING about them has arrived  at  the  same  conclusion:  that
>          it  would  be  physically  impossible  for  them to fly, but that
>          they obviously HAD to fly in  order to  survive (since  they were
>          built for  flying and  could not have earned a living otherwise),

	Well, this could really only apply to Pteranodon and the other
larger types, since *most* ptreosaurs were much smaller and would have
had no problem even according to the most skeptical student. Of
course, I claim that the ones whoe *really* thought about it decided
that even the large species could fly.

>          ...   The following quotes
>          are from Adrian Desmond (from "The Hot-Blooded Dinosaurs"):
>
>
>               "The combination  of great  size and  negligable weight must
>               necessarily have resulted in some fragility.  It is  easy to
>               imagine  that  the  paper-thin  tubular bones supporting the
>               gigantic wings would have made landing dangerous.  How could
>               the  creature  have  alighted  without shattering all of its
>               bones?"
>
>
>               "Many larger  birds  have  to  achieve  a  certain  speed by
>               running  and  flapping  before  they can take off and others
>               have to produce a  wing beat  speed approaching  hovering in
>               order to rise.  To achieve hovering with a twenty three foot
>               wingspread, Pteranodon would have required 220 lbs of flight
>               muscles as  efficient as  those of hummingbirds.  But it had
>               reduced  its  musculature  to  about  8   lbs.,  so   it  is
>               inconcievable   that   Pteranodon   could   have  taken  off
>               actively."
>
	Gotcha, these are out of context, I have that book. Dr Desmond
goes on to point out that these animals were *gliders*, not hoverers,
so the dynamics of a Hummingbird simply do not apply. In fact the wing
proportions are those of an Albatross, a gliding bird which almost
never lands. In fact when an Albatross lands it usually crashes, that
is why they are called Goony Birds! In short, the Pteranodon didn't
need all that muscle, because it didn't use the same airodynamics as a
Hummingbird with it tiny little wings. A recent journal article, which
I have not yet been able to relocate for review here, calcualted the
stall speed for a Pteranodo, that is the *minimum* *air* speed needed
to sustain flight. The result was an incredible ~5mph. This means that
it could take off by just facing into the wind and spreading it wings!
No need at all for *any* flapping during take-off, and only a slight
amount of trim and lift type flapping during flight, you know a little
push now and again just to make sure it stays up. Eight lbs of muscle
would be plenty adequate for this.

>
>	(More quotes written in a popular "gee whiz" style, for drama,
	 which seem to say the same thing as the ones above, and are
	 equally out of context)

>               Wann Langston,  writing in  the Feb. 81  issue of Scientific
>          American,   had   this   to   say   about  the  Texas  pterosaurs
>          (Quetzalcoatlus):
>
>               "Aeronautical engineers quickly pointed out, however, that a
>               pterosaur with  the shape  of a pteranodon and a wingspan of
>               15.5 meters might have weighed as much as 136 kilograms.  It
>               would then  have lacked  the muscle  power to maintain level
>               flight by flapping its wings.  Moreover, the strength of the
>               wing bones  would perhaps have been insufficient to bear the
>               stresses the wings would have  had  to  endure.
	More calculations based on a *flapping* flight in what was
probably a glider!

-- 

				Sarima (Stanley Friesen)

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