I woke up this AM with this rudder oscillation issue on my mind. Jim O and Troy Newman had given me several ideas to try. I put the 8411 back in and watched it “dance!”

But first I tried a field-fix that a JR service engineer had given me. I fitted an O-ring across the two pull-pull wires inside the fuselage. This was easy to do. Just undo the servo arm and slip the 3/4” O-ring over the wires. It stops the oscillation as soon as it starts, after you flick the rudder stick. Probably not a permanent fix but could get you out of trouble at a contest.

I replaced the ali-output shaft with a nylon shaft so that the gear train was all nylon. I still got the oscillation dance but not all of the time and it was tighter.

The next thing that I tried was tightening the wires. (Minus the O-ring) Not much change. Definitely looked like the spring tension in the wires was a contributing factor.

Next I took two wires of different thickness and strung them up with equal, but light loads. Then I added 10 lb to each and could see much more stretch in the thinner of the two wires. Definitely springy!

I had the thinner wire on the plane so off it came. The thicker wire did not stop the dance but it could easily be seen as significantly less of a swing, (2” down to 1/4”).

Then the multi-strand wire was traded out for a single piano wire on each side. After that there was no way that I could get the servo to dance. I tried more and less tensions. No change!

The weight difference was .09 oz

I put the O-ring back on to stop any pull-pull wire “humming” and that how it has been left.

[In case you think I have lost it, don’t forget that we can’t fly yet and the building is all done!]

Flight trials will tell the rest of the story.

Regards,

Eric.