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Couldn't agree more with Rob Wolf's comments regarding the subject.

Besides, without instrumenting your Lancair with accelerometers, over the
entire surface area (and probably much of the internal surfaces too), and
then flying an exhausting test schedule to include every possible variation
in your flight regime, you'll never know whether or not any part of your
airframe has an abnormal response to vibratory excitation. Further, even if
you did all this and actually found a resonance, it's still questionable
whether you could determine if it was potentially destructive.

Proof of the pudding being in the eating, as they say, if surface resonances
were going to be a problem, it would certainly reared it's head by now as
there are many Lancairs with enough time on them that they should have
shaken to pieces long ago.

Having recently retired from the "big airplane" industry, I can understand
how the qualification requirements for flight components in that world would
naturally instill a sense of paranoia in an enginee. Our little four bangers
just do not generate the kind of energy over the frequency range that a B-1B
(my last project, for over 20 years!) does when taking off with all four
engines going at full song, i.e. full augment (afterburners).

Dan Schaefer

LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
Builders' Bookstore:   http://www.buildersbooks.com/lancair

Please send your photos and drawings to marvkaye@olsusa.com.