Hi,

Does the model climb quickly at full throttle? If so, you can adjust the elevator linkage and/or trim to give enough down elevator at neutral stick position so that the model climbs only slowly at full throttle. Then when inverted, not so much forward stick will be required to maintain level flight. You may not have enough movement available on the elevator to allow all the down trim which will be required.

Another approach, if the wing attachment system allows, shim the TRAILING EDGE of the wing UP about 1/16 to 1/8 inch at a time until the model will only slowly climb when at full throttle with neutral elevator trim. It may require quite a thick shim. With the correct shim, even a flat bottom or Clark Y wing can be made to do outside loops, given enough down elevator control.

Either way should give the desired result. Moving the CG back too far can cause lots of excitement. A SLIGHTLY tail heavy model is VERY pitch sensitive; just a little too tail heavy and it will take off very quickly and crash almost as quickly. I would suggest not more than about 1/3 back from the leading edge to begin with.

Any thing you do will be a compromise; sounds like you need a semi-symmetrical or fully symmetrical wing.

Have fun.