My only comment on rudder trim is it adds some weight to the rudder (obviously).  That can create some balance problems.  You might consider extending the counterbalance arm to compensate for the weight of the trim.

 

The IV and ES rudders were originally designed without trim.  The counterbalance arm was adequate.  Then they added trim.  I also think the new fastbuild rudder is heavier, more flox along the ribs.  Both modifications add weight.  The counterbalance arm is too short to allow room for the lead weight.  I had to drill out some lead and replace it with tungsten to get my rudder balanced.

 

I really don't mess with my rudder trim much, but a IV with long climbs to high altitudes surely would benefit from rudder trim.

 

Mike Easley

Super ES