Hi John, Yes, you are correct, the location of the CG is different on every pattern plane. And again yes, there are a number of other factors that impact the location of the CG. Notably the size/weight of the electric motor, location of the battery tray and whether or not you use two small elevator servos in the rear of the fuse or stab versus an elevator pushrod assembly/DEPS with servo near the rudder servo mid-ship. Note, the Otop was not a true 2m plane, it was somewhat shorter in length. The best I can recall, the Otop flew best with the CG approx 5mm in front of the wing tube. Also, let me add the capacity/mahs/c ratings which ultimately determines the total weight of the batteries and whether you use 8s or 10s packs in series that you obviously know about. John, I have a question for you. From my calculations his 6s set-up is pulling approx 75 amps, right? At 1850 watts and based on my past experience, I really question this Otop's performance. Is he going to try to fly this combination in a pattern contest? The reason I ask is that I feel he might be disappointed due to it being underpowered and very tail heavy. Think back about the total weight and the overall performance of this plane when you flew it with a 10s set-up. Remember what the performance felt like pulling approx 2500-3000 watts? I hope I have been able to help in a small way, Everette