REFLECTOR: wheel shimmy

[Scott Baker]

I agree with everything Al says in this message.
The nose wheel fork rotational tension should be checked before every flight.
For most this involves manually lifting the nose off the ground and while doing so, standing on one foot, using the free foot to push the rear portion of the fork to 'test' the tension.
As aircraft nose weights become heavier, and the lifting strength of pilot/owners becomes weaker - its easy to see why the nose fork tension is not checked as often as it should.
The liklihood of shimmey is much greater when the turning force on the nose fork is weak.  Nose fork shimmey should not come as a surprise to those who last checked the nose fork tension at the last Conditional Inspection.  A better shimmey dampener (better mouse trap) is preferred.  I like Richard Vandersteen's set up.  Many people like Ken Mishler's immobilizer set up.  Developing a better shimmey dampener is on Velocity's list of things to do.
Scott Baker
  ----- Original Message ----- 
  From: Al Gietzen 
  To: 'Velocity' ; 'Velocity Aircraft Owners and Builders list' 
  Sent: Thursday, February 19, 2009 12:00 PM
  Subject: Re: REFLECTOR: wheel shimmy


  . It seems the answer usually goes to set the tension on the front wheel to 14 lbs of 

  pull or something like that and you should not have a problem. Is this not true? I have heard that this should be on the preflight check list. Does this number change and really need to be adjusted regularly?



  Ron;

  My take is that, with perhaps a few exceptions, if you keep the 14# tension on the wheel pivot, it will not shimmy.  I found the during the first 20-30 hrs of flying time the tension did slowly change; depending on the number of takeoffs and landings. Now I find it changes very little, but I check it about every dozen landings.  A couple times a year I remove the wheel assembly and clean and re-grease. I use 12# tension, and it works fine.



  Or perhaps  there are people that feel that there is a better mouse trap out 

  there and are working toward a simpler/ better design for the front wheel which is great. So is there a steering Issue?



  Yes; we're looking for a better mouse trap; because, although not a serious steering issue; it is an annoyance.  If you are starting from a stop, and the wheel is turned in a direction you don't want to go, it takes a lot of power to get the wheel to turn, and then it is likely to over-steer. Best make sure the wheel is pointed in the right direction before getting in the plane; or get out and do it if you're already in. Slow speed taxi with turns requires an excess of power to overcome the braking needed to steer. 



  You get used to it, but life taxing would certainly be more pleasant if the damn wheel turned easier.



  Al



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