[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Fw: pterosaur femora sprawl



Oops.  Forgot to send this to the list.
JimC

----- Original Message ----- From: "jrc" <jrccea@bellsouth.net>
To: <gerarus@westnet.com.au>
Sent: Tuesday, June 03, 2008 9:29 AM
Subject: Re: pterosaur femora sprawl



John Conway and I did a poster on it at the 7th International Congress on Vertebrate Morphology several years ago, and I adressed it in an hour-long talk at SSA '99, in early 1999. I was a few years in front of Mike, but he independently came up with the same launch scenario, and our thinking is quite similar. Flatland leaping launch ability in calm winds and at high density altitudes (hot day).

The ground doesn't get in the way during the launch because the front feet (hands) are the last thing to leave the ground, and the animal is above steady-state stall speed when they do so. At that point, the hindlimbs have already moved most of the way to flight position and a fairly standard flapping upstroke is initiated, with the exception that the hands are further aft than usual during that part of an upstroke and the wings are still mostly folded (there is some partial opening due to inertial lag as the shoulders move forward during the initial leap and the wingtips lag behind). When the inner wings rise high enough during that first upstroke to allow the wingtips to clear the ground, the wings are actively unfolded (generating considerable lift in the the process), and the latter part of that first upstroke follows the standard locus, as does the ensuing first downstroke.
.
JimC


----- Original Message ----- From: "Christopher Taylor" <gerarus@westnet.com.au>
To: <mhabib5@jhmi.edu>
Cc: "'dinosaur mailing list'" <dinosaur@usc.edu>
Sent: Tuesday, June 03, 2008 8:43 AM
Subject: RE: pterosaur femora sprawl



By "storyboarding", Dave, do you mean the process of what happened when
in the course of the launch? Actually, I'd be interested in seeing this
myself - not being overly familiar with aerodynamics, I have to admit
that when I try to imagine it the ground keeps getting in the way. Where
am I getting confused?

   Cheers,

Christopher Taylor