Mark W wrote: > If the caster angle and wheel & tire balance are right, you shouldn't have > this problem... think GM/Ford/Chrysler front end alignment... not shopping > cart. I've yet to see a Corvette experience 'shimmy' at speeds exceeding > anything a KR would land at.
I would have to disagree with that. You can have a perfectly balanced wheel/tire, but external forces such as which way the wheel is pointed at touchdown, or even which way the wind is blowing, can get the shimmy started. That's a side to side phenomenon, not a "perpendicular to the axis" thing. But it's really a matter of insufficient damping, which is the real cure for a shimmy like that, regardless of what got it started. There's an aerodynamic effect (it has a name but it's been 10 years since I read about it) which describes how this oscillation happens to aero controls, or even stop signs in a high wind...similar to flutter. Damping is the key to fixing it, not balance. Stop signs have no damping, just a metal post which acts a spring to help perpetuate it. Diehl accounts for damping through washers or something, and as mentioned, there's an adjustment/cure. If that were my plane I'd have that nose gear off and be checking for cracks and wallowed out attachment points though.... Mark Langford N56ML "at" hiwaay.net website at http://www.N56ML.com
