At first with no RX battery my plane balanced tail heavy. Too heavy. I placed my 3s 1050mAh Lipo right under the fuel tank. Oh, my fuel tank is pulled back right infront of the wing tubes. I have an aluminum spinner on the nose, remote glow driver right below the cowl, and extra epoxy and hard wood supporting the firewall from the inside and beefed up the wood around the landing gear area. Balances now exactly at 120mm.