Mike I haven't found a bad place in the CG range on mine. This is my second CG ULT and it's 5 years old. I would try it even further back but I don't want to add any lead. As it is I have a 1500mah battery zip tied to the 1st bulkhead behind the wing opening. There has to be a point were the thing gets unstable i just have not found it.

David