Greetings,
 
Thanks for all the comments, but I do think some of you are getting a bit ahead of me on this :-)  The following are mostly random thoughts.
 
The phenomenon is really amazing to me, but until more combinations are tested, I'm not sure if it's even a problem.  My gut feeling is that it happens to some extent with any flexible prop, and requires some instability in thrust to set it off.  Low rpms and changing speeds seem to set it off for sure.  IVO props are more flexible, and have an even worse problem, but the only caution is to allow 5" clearance at the tips of the IVO so it won't hit anything.  Even with that clearance, my old IVO on the Kolb hit the back of the fuselage cage on startup one day.  They flex a LOT.  Common sense would dictate that too much of this flexing is clearly not good, and a line will have to be drawn before prop, or engine damage is done, but who can say where that line needs to be without a ton of testing?     A single rotor Mazda (without a flywheel) has to be about the worst case, because it's got a big powerful combustion chamber.  Rotax had plenty of single cylinder engines, but at most, they were half the size of the single Mazda chamber.  By the time any "normal" engine gets to the displacement of the single rotor Mazda, it's got at least two cylinders to help smooth things out.  Clearly, what we need is a 2 or 3 rotor engine that's sized to make an easy 100 HP.  My goal will be to re-video the current configuration, perhaps with a yardstick or some other markings in the picture for scale.  I'll zoom it more to get just the engine and prop, for more detail.  I might even use the real video camera instead of my Cannon PowerShot 3 :-)  I'll video set rpms from about 2000 to maybe 5000, depending on how brave I feel about my trailer stand.  Not sure when this will happen, as I'll be out of town for a few days getting dual in a similar gyro (nice try Lynn <g>).   I smell fajitas, and my beer is empty.  Gotta go :-)  Rusty