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Fw: Water-bourne pterosaur launch



Since Mike responded to the list as well as to Mark, I will also (see offlist response to Mark below). As an aside, I do have thoughts about how a pterosaur might be able to break free of the water in a single leap, but as I mentioned below -- have not quantified it yet. As Mike says, it certainly possible to break free in a series of initial 'pushoffs'. Due to the high density of water and the focused loading near the wing finger pivot, the surface area in contact with the water near the wingfinger pivot has to be closely controlled -- unlike uniformly varying spanwise flight loads into the skeletal spar, the water launch loads are almost point loads (but then, so are the terrestrial launch loads).
JimC

----- Original Message ----- From: "jrc" <jrccea@bellsouth.net>
To: "Mark Witton" <Mark.Witton@port.ac.uk>
Cc: "Habib, Michael" <MHabib@Chatham.edu>
Sent: Tuesday, October 06, 2009 2:17 PM
Subject: Re: Water-bourne pterosaur launch


Offlist.
Mike and I are working on it together. Actually, somewhat independently and merging our thoughts every few weeks when we come up with anything interesting. Plan to do a joint presentation at Beijing next year.

The two biggest problems are
1) Initial slippage through the water at the wing finger pivot -- we have a handle on that, and it's not all that severe a problem. 2) Breaking the initial 'suction' when the neck, body, hindlimbs, and innermost wing first start to break free of the water. Have thoughts about that, but I've not quantified it yet -- Mike may have. In any event, that bit would be quite species specific.
Jim

----- Original Message ----- From: "Mark Witton" <Mark.Witton@port.ac.uk>
To: <jrccea@bellsouth.net>; <erikboehm07@yahoo.com>
Cc: <dinosaur@usc.edu>
Sent: Tuesday, October 06, 2009 2:54 AM
Subject: Water-bourne pterosaur launch


Chaps,

Quick question: in numerous threads on pterosaur launch there's been mentions of pterosaurs taking off from water, but, to my knowledge, it's never really been discussed further. The mechanics of water launching have to be quite different to those acting on terrestrially-launching critters, and I've never really been too sure how it would work. Anyone (and I'm particularly glancing over at Mike and Jim here, seeing as they're typically the guys saying it can happen) come up with a suitable mechanism for it?

Back to work.

Mark