Elevator Trim
I borrowed this idea from the GlasAir aircraft and my Piper
Toamahawk. I'm using the MAC trim servo out of the old elevator
to move a shaft fore and aft which pulls on a set of springs to bias
the elevator push rod fore and aft. While this trim system does
work, it doesn't work particularly well and is still in need of some
refinement and tuning.
2007 update- While this elevator trim does work, it doesn't work well and I do not recommend using this method. - Jeff

