Originally Posted by astr0lite
A kind soul at the flying field finally helped me sort this out. He recommended 1/3 of the wing chord for the CG which was significantly less than 100-110mm from the leading edge (more like 60mm-70mm). After moving my batteries all the way forward and adding a 3s 2200 as ballast (did not have my FPV gear installed) the CG was near the spar if not a little in front of it and it flew great!
there has been an extensive and very qualified discussion on the CoG in this thread. Try searching "this thread" for observations and theory on the issue.
In short, the SW flies more economically with the CoG at the rear of the usable interval, but some (including myself to some degree) find that it flies more "nicely" with the CoG a bit more forward.