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I need help with torque tube friction

TClinton

Member
I am building an F1 Rocket but the control system is essentially the same as an RV-8 in design and operation. I am not flying yet but should be soon. Anyhow, the problem I have is that when I tighten the jam nuts that hold the two rod end bearings that the control torque tube swings left and right on - it binds up creating a lot of friction for the ailerons. Pitch is perfectly smooth.
Do you think this is caused by me having the two rod end bearings being adjusted to slightly different lengths? Maybe I need to slot the hole that the front rod end goes through so it can be moved slightly (maybe 1/16" forward or backwards) to make sure that both front and aft rod end bearings are perfectly aligned with each other.
Any thoughts would be appreciated? Thanks, Tony
 
Tony,

I wrestled with this one for weeks. YMMV but what I found was a misalignment of the rod end bearings in the vertical plane. I had to adjust both the front and the back to find the sweet spot. In my instance, there was very little margin for error. Any misalignment would place a side load on the bearing creating friction.

I have also heard of the front rod end bearing bracket, where it is attached to the front spar, can cause a similar issue if it is not mounted square.

Good luck,

Mike
 
When aligned properly and the jam nuts tightened you have to be able to rotate the tube on the bearings from one end of the throw to the other, if not readjust. If it can or rotate a bit it is jamming.
 
Do the plans call for washers each side of the rod end bearing ball allowing more swivel action? Not AN960 washers, but the smaller OD washers used on control linkages
 
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