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Just curious, but did either of these tests include conditioning the
composite samples to simulate hot/humid conditions? Moisture has a huge
impact on the strength of composites. It can impact the stiffness as well.
I'd be VERY careful about going past a published flutter limit - Lancair may
be adding an extra margin of safety to account for the behavior of the
structure in a test lab vs. real life.

Paul Klusman


In a message dated 2/24/02 1:03:48 PM EST, Brent@regandesigns.com writes:

<< The design stiffness of the was determined by Martin Hollmann
 who, being the good engineer he is, performed tests on sample layups to
 determine their stiffness. (see "Composite Aircraft Design" M.
 Hollmann). Sounds great ..... except that the procedure Martin  used did
 not adequately allow for nonlinearities in the test fixture. According
 to a former PAC engineer, these tests were repeated for the certified
 aircraft program and it was determined that the original values were too
 low by about 25%. Based on the newer values, Mmo should be 0.58 or 342
 KTAS at FL300. >>
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