I have used Kevlar closed-loop connections on seven models. They have proved to be very satisfactory.

On first acquaintance, Kevlar thread seems like ordinary sewing thread. In fact, it is very much stronger,   and most importantly it's stretch under tension load is almost zero.

The drawings show typical installations.

I obtained my Kevlar thread and ptfe tube from Mike Woodhouse ( www.freeflightsupplies.co.uk  tel 01603457754)

Ackerman effect --- Important

Diagram 1.  Angle A is 90 degrees. As control surface moves, thread tension stays constant.

Diagram 2.  Angle B is more than 90 degrees. Thread tension, and consequent friction, increase when the control surface moves away from the neutral position. Avoid this set-up.

Diagram 3.  Angle C is less than 90 degrees. Thread tension reduces when the control surface moves away from the neutral position. This is the correct set-up. Angle C should be about 85 degrees.