Mine balanced at 3 1/2 to 3 3/4 back from leading edge. This was with the engine pushed out as far to the front as i could get it. I also put the battery pack on top of the fuel tank just behind the firewall. After this no weight was needed to balance it where the spec's said it should be. The plane flew very good but did not hover very well at this balance point, so i am going to try moveing the balance to add a little tail weight. hope this helps.