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Re: Pterosaur-inspired aircraft design

Thanks to Ben for the heads up on several of the recent paleo literature.  I am 
curious what other listers think of the Lind and Chatterjee paper cited below.  
I will admit that my own opinion is relatively negative.  I do not see much 
relevance to pterosaurs, nor to I see any great aerodynamic breakthroughs here 
- the anteriorly placed vertical tail effect was known previously, and it does 
not seem to do much that other, less drastic, design alterations cannot 
accomplish with less material and stability loss.  I see limited relevance to 
pterosaurs because the use of the crest as an aerodynamically active surface 
for turning was already falsified by Ross Elgin and coauthors back in 2007, and 
actually makes very little sense from the standpoint of aerodynamic theory to 
begin with.  I am interested to know if anyone here on the list understands why 
Chatterjee continues to insist that the crests of pterosaurs might have had 
function in maneuvering during flight.


--Mike Habib

Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
(443) 280-0181

On Jun 14, 2011, at 4:33 PM, bh480@scn.org wrote:

> From: Ben Creisler
> bh480@scn.org
> The news story:
> http://www.physorg.com/news/2011-06-pterosaur-inspired-aircraft-sharper.html
> The paper:
> Brian Roberts, Rick Lind and Sankar Chatterjee (2011)
> Flight dynamics of a pterosaur-inspired aircraft utilizing a
> variable-placement vertical tail. 
> Bioinspiration & Biomimetics 6(2): 
> doi: 10.1088/1748-3182/6/2/026010
> http://iopscience.iop.org/1748-3190/6/2/026010
> Mission performance for small aircraft is often dependent on the turn
> radius. Various biologically inspired concepts have demonstrated that
> performance can be improved by morphing the wings in a manner similar to
> birds and bats; however, the morphing of the vertical tail has received
> less attention since neither birds nor bats have an appreciable vertical
> tail. This paper investigates a design that incorporates the morphing of
> the vertical tail based on the cranial crest of a pterosaur. The
> aerodynamics demonstrate a reduction in the turn radius of 14% when placing
> the tail over the nose in comparison to a traditional aft-placed vertical
> tail. The flight dynamics associated with this configuration has unique
> characteristics such as a Dutch-roll mode with excessive roll motion and a
> skid divergence that replaces the roll convergence.
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