REFLECTOR: Aileron Feel and Trim Spring Relationship

[LAURA WALKER]

I too had the feeling that mine were way too resistive on the ground, but I resisted the temptation to inject anything into the cables. I did a couple of things differently than most: I believe that Velocity's stock trim springs could stand to be much stronger to better balance the elevator and to make the standard string trim system work better. I did some testing with the stock springs and different ways to add friction to the trim capstan to increase friction and keep the string from slipping. I found that if one increases the friction too much, the system can drag the weak springs around either the capstan or the pulley at the other side, thus destroying the springs and possibly compromising the aileron functioning. I decided to go with stronger springs, safety stops for the capstan and pulley, and a series of 5 pairs of evenly-spaced holes drilled up the length of the rear aileron bellcrank. I went to www.mcmaster.com and ordered about 10 different
 pairs of their precision and ultra-precision springs. The difficult part of this experiment is that the springs that feel the best cannot tolerate the total extension necessary for complete control deflection. I finally settled on a slightly lower mounting point on the bellcrank and a fairly strong spring. My safety stops are just small pieces of steel angle riveted to the steel whale tail backing plate: they are mounted above the capstan and pulley so that the 90 degree arm is just above the string to keep the springs from being able to be drawn onto said capstan and pulley.

The result here is that it both flies very well, and hides the cable resistance on the ground.  Also, it DOES NOT SLIP in flight. I then coated all the external metal parts with dry lube, and reamed out both the inner and outer rubber dust caps on each cable. 

I don't have my build manual with me, but if anyone wants to know the spring's part number, post a request and I will get it for you.

Bill Walker