Message-Id: <9903199218.AA921856344@inet001.cardell.com>
Date: Fri, 19 Mar 99 10:03:21 -0500
From: <dechaze@cardell.com>
To: <lancair.list@olsusa.com>
Subject: Re:flutter
Mime-Version: 1.0

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I've been interested in the 320 flutter debate both from an academic and
self-interest point of view.  As I've mentioned a couple of times in the past,
I've wondered about a weakness in the flutter analysis that Martin has performed
(and anyone else for that mattter).  The weakness is that the aerodynamic part
of the study is unverified by actual flight test.  The FEA study, that was
validated by ground vibration testing, is only half the equation.   What I'm
saying is, I don't know how well Martin's software predicts aerodynamic behavior
for our aircraft out our flying speeds.  The fact that this code is used by
Boeing, and is said to be a standard, is not convincing.  Boeing's airplanes all
fly at far higher airspeeds.  Does this make a difference?  I don't know, but
the software's performance at low flying speed would have to be tested and
validated.  

One way to do this is to validate the software after-the-fact at an accident of
a similar aircraft to the 320.  Martin infers that this has been done but does
not develop the case.  "I have been performing flutter analysis now for 25 years
and my flutter predictions have always been correct."  Unfortunately, I don't
know what this means.  Perhaps Mr. Hollman could list his academic credentials. 
I find this sometimes helps in assessing credibility.  

Naturally, to be fair, the same questions would be directed to Lancair's other
analysts, but they have the benefit of many of years of trouble-free flight
experience to support their position.

Best Regards,
Ed de Chazal