Hmm 1 inch behind the spar? Ok, you go first. Ha ha ha I think I am shooting between the spar and 1/2" behind the spar. World models makes a 60 size plane that is just a tad larger but we may be able to cheat and view their CG and come close. They usually post their manuals and I have many of their planes all of which flew great. Their's is a 60" span (635 sq. inches) where ours is 58" span (550sq inches). Kyosho also makes a 40 size but their wing dimensions are quite a bit smaller and so is the all up weight.