The launch trim is probably just a little hot side.
Originally Posted by liftchaser
Without seeing it I'd guess the tow hook is too far aft relative to the CG. I usually set mine at 3 to 4 mm ahead of the CG to start. On a calm day, or if there is a tailwind wind component at launch, I have to be careful to avoid a stall on the line in the early stages of the launch, which produces a rapid yaw away from the line similar to what you're seeing.
Or then elevator trim is little different from JGs other Supra. These differences are very different to measure. You just have to trim the plane hotter and hotter, and them come little back.
Originally Posted by RC-JG
(or am i leaving launch flap in too long!!)
This makes me think how you use launch camber in launch? You should have a setting that gives both - max tension and adequate stability - all through the launch. If not, then there is something wrong in the basic launch dynamics. Maybe you are trying to achieve launch trim with combination of relatively forward hook position and some up trim?
Some of us have then more complicated launch set ups. I use 2 stage setup with 2 launch phases. The second phase has less camber, but the second launch phase with less camber is not for stability, it is used for more speed.