I had no shimmy during the first 300 hours (the life of the cheapy tires that came with the kit). However, after I put new Michelin tires on, I had a fore-aft shimmy at 23 knots. I did put lead in the forwardmost part of the main wheel fairings, to no avail. I do think balancing them is a good idea, though, as it will minimize pitching moments on the fairing mounts as the tires roll over bumps.

Shimmy modes are simply resonances (defined as some input frequency being equal to some natural vibration frequency). The natural frequency of something depends only on its spring constant (in the direction of interest) and mass. Adding energy absorption clearly will help (lower air pressure, or wood, which is really only designed as an energy absorber, not a stiffener), but there is no general solution which will work for all.

As for me, I simply do not taxi at 23 knots.
 
I'm assuming you balenced the tires when you put the michelins on? It's kinda odd for that to occur, and for my money is completely fixable. When you split the wheels did you clock the brake discs in the same locations they were originally?
 
william weesner said:
has anyone other considered balancing thier wheel pants to help minimize shimmy
http://home.mindspring.com/~rv6/RV6site/wheel pants.htm
Click to expand...


I balanced my wheel pants using almost exactly the same method, although my balance apparatus was simpler.

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One 'improvement' I would recommend.... don't mix the lead shot with epoxy... simply build a sturdy dam to hold it all in place. That way, if you ever want to remove it, just drill a big hole and shake it all out. Someday, I'll do that to see if I get shimmy. I have no shimmy now (wooden dampners and balanced pants)

Also, reinforce the screw attachment points on the side of the nose cones more than called for in the plans. There will be more stress on them with the additional weight.


Vern Little
 
I recommend waiting until after you fly the plane to worry about balancing the wheelpants. Balancing wheelpants is something that can be done later, and there is no need to add the extra weight unless your airplane has a tendancy to shimmy. My experience is that balanced wheelpants are no guaranteed fix for shimmy. My plane has balanced wheelpants and I experience shimmy from time to time.
 
yep - I'd encourage you to wait to see if you end up with shimmy. Out of four local RV 7's and 9's, none had any shimmy - no balanced pants or stiffeners. So perhaps the odds are in your favor?
 
William,

I'll chime in too, since it's my wheelpants you're looking at on the web. I agree completely with the advice to wait and see. Fly it first, and if you have shimmy, start playing with the fixes. Shimmy is an elusive thing, some have it, some don't.

As for balanced pants not making a difference- I understand Alex's reasoning. It makes sense. Alex could probably explain to me why a bumblebee can't fly and have me believing it. But, the proof is in the pudding. It really, really did make a difference. One of the EAA old-timers gave me the idea and he swears by it. He built the first all-fiberglass homebuilt in the late 60s (still flying) and has balanced lots of wheelpants.
 
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