If you can give a better explanation of what the plane is doing it would be better!!!!!.

Normally in all looping maneuvers you will have to give just a little right rudder to compensate for the engine torque issues.

If it turns to the right when the transition of the loop begins,it could be that your lateral balance is not good,the right wing is heavy.

It could also be that your elevator halves are not in line with each other,the right elevator half is more up than the left half thus acting like a aileron.
Check and see if they are in line with each other.

It could also be that you have too much right thrust,but if your vertical lines are straight that`s not the problem.

That`s a nice patternship trainer you`ve got there keep flying it till it can`t fly no more.

I hope this helps.
Greg.
www.arubarcclub.com