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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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