CG?
Don, I'm running the same exact set-up (OS 46 fx) except Hitec digitals, but my batt. is in the front and Rx in the back and engine more towards the front. Mine balances at about 2 1/4" back and does fine.
I would re-check everything, something seems wrong. Oh BTW, I do have the pre-painted version. (Spidey)
George