Hi Pete, Thanks very much for your reply, it is really helpful to get some practical advice. In fact I had almost decided to do what you suggest - to open up the motor mount bulkhead and move the battery forward a little, so now I will go ahead and do it. I am slightly concerned that I need to do it though as I can't see any obvious explanation for the tail heaviness. The motor I plan to use, a Hacker A30 12L, is about 10gm lighter than the AXI recommended but I doubt that would explain it. I had already noticed that the side pillars were a little weak and had beefed them up, both the front and back ones. Now I'll add the diagonal braces as you suggest. I looked at the threads you pointed me to, and they do provide some helpful comments, although no one mentions battery mounting problems! Maybe they are just par for the course with ARTFs? Anyway thanks for all your help, I hope to maiden next week as long as the wind stays fairly quiet. Ken