
There are several HUGE UCD threads in th3 3D and ARF forums. There are answers to just about anything there and the people are very friendly.
For the record...I fly my UCDs both the 46 and 60 size, at a CG of 6". I don't think you want to go further back than that. At least, let's say, it dosn't need to be further back than that. Mine hovers fine and tumbles, flat spins (even a rising flat spin) rolling circles and waterfalls etc. just fine. It is a very fun airplane. One thing it will not do well is Knife Edge. it's terrible at that. If I want to KE....I fly another plane. Everything else it seems to do pretty good.
Hope this helps.
Thanks
Barry