If you are reffering to the the Giant Scale Planes P-47 55.5". Then you have a tough job ahead of you. My friend crashed his last week after many painful weekends of trying to figure out where the correct position of the center of gravity is and trying to get at least one decent flight out of his model.
I checked the center of gravity of this plane after assembly on my GP gadget and it came out alright so all I can guess is that the wing loading may have been too high or the model has fawlty aerodynamics.
We need to hear from someone who has flown this P-47 successfully.