SHHISSHHH! No one supposed to see that bolt. That bolt called laziness. In truth I have that bolt threaded in the ply back there by the tail to easily change the cg. Im to lazy to move things around inside the Plane, so I just add a washer or remove a washer to which ever way I want the cg to go. It really not noticable from the top of the Plane, but it sure stands out like a sore thumb when you are taking photos of the belly side. I am not crazy about using stick on weights, but I do prefer to make all the adjustment on the outside of the Plane, and this also makes it easier for me to make simple changes at the flying field. Alot of my planes have that ugly bolt on the bottom side, and I have a selection of washers weighed out in different weights. Just another one of my do it different things. You should have seen me back in my duct tape fixes everything days. I was quite the Macgiver with my duct tape and a role of bailing wire.lol