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Re: Sharovipteryx - delta-winged glider? .don'tthink so.

----- Original Message ----- From: "David Peters" <davidrpeters@earthlink.net>
To: <dinosaur@usc.edu>; <twilliams_alpha@hotmail.com>; <jrccea@bellsouth.net>
Sent: Friday, March 24, 2006 5:56 AM
Subject: Re: Sharovipteryx - delta-winged glider? .don'tthink so.

And pteroids are useful for that anterior membrane,
the propatagium which aids in flight.

In those animals that have them, one of the functions of pteroids is as a flutter prevention device -- to maintain adequate tension in the entire membrane when the wing (or canard, as the case might be) is partially retracted in flight. It is used to help maintain the aeroelastic number above the bistable limit and/or the flutter limit. Among other things, it allows the animal to fly at a lower lift coefficient (faster) than it might otherwise be able to accomplish, so opens up the flight envelope (the range between stall and top speed).

In pterosaurs that's all the cervicals are capable of, elevation and depression.

They are also capable of lateral motion, although it is rather limited in the longer necked species. The ones I've looked at and assembled do not appear to be capable of rotation about their long axis, but I don't know if that is true of all pterosaurs.