Apparently you are supposed to move the wing tube around until you like the CG. Pretty strange at least to me. After reading through all of the threads I put the tube about 1/8" aft of the most forward position it can go and glued it there. That's about where Eric Henderson put it and he was happy with it. With everything else located as shown and with the battery forward It should balance well enough to fly safely. Then it is just a function of trimming it and moving the battery around until it flies like you want it. If I ever get an engine that runs I will test this theory by actually flying the thing.

Rick H.