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

Re: Tail feathers

>> Pterosaurs also have a pteroid bone that supported the
>> brachipagatium,


OOPS.  In my haste I must have accidently said the wrong term.  

<<No. Wrong location and the pteroid was submerged. The pteroid provided 
a bit of a Kruger flap function at the leading edge, but that doesn't 
appear to have been it's primary purpose (a tiny bit of leading edge 
deflection goes a looong way). The alula function was provided by the 
small fingers at the distal end of metacarpal IV.>>

I know that it was in the wrong position but it could have functioned 
like the alula.  Why does it support the propagatium which would have 
provided drag?

<<No.  The fibers were crucial to the flight performance of the 
pterosaur wing, but there were no similarities whatever between their 
method of operation and those of feathers.  Bear in mind that feathers 
can withstand longitudinal and torsional bending moments and can carry 
both tension and limited compression.  The pterosaur fibers could carry 
no bending loads, only tension, which is part of the reason for the 
distal bend in the metacarpal which functioned to alleviate spanwise 
tensile stresses. The spoon-shaped joints between ph 1&2 and ph 2*3 
served the same purpose. One of the most fascinating things about the 
pterosaur wing is the mechanism for gust load alleviation, since the 
flexible membrane could not directly apply torsional loads into the 
skeletal spar.  This mechanism is particularly elegant in Azhdarchids.>>

My comparison was rather loose...  They are, though they still are 
connected together, differienciated segments like feathers.  

>Try Harry Erwin.  I'm impressed by initial communications with him.

Thanks.  You have an address?

Matt Troutman

Get Your Private, Free Email at http://www.hotmail.com