i dont know if this will be of interest to anyone but i did discover that on my ucd60 size when i moved my tank to cg that the weight transfer did alter my knife so that when rudder was applied it dove to the belly a lot harder(100% HARDER) and i figured out that when i moved the tank that it affected the elevator trim to the down about 3-4 clicks making inverted flight almost effortless with no down input, but when i went to knife the extra down was the culprit that influenced the hard dive to the belly, basics, might help someone