Back to the last model of the true trinity of this build . . . the P-51:

The P-51 has different construction being a U-shaped fuse with an open bottom. I need to glue cross-grain balsa on the bottom to close it up eventually. But, this means that I need something more substantial that 2 layers of FG cloth to glue it to. So, it gets a piece of 3/32" balsa sheet, followed by another layer of FG cloth. This sandwich construction makes it very rigid, and also absorbs the stresses of the wing saddle during hard landings, beings there are no fillets on this model. (Without a fillet, the edge of the fuse side would be so sharp it would cut through the wing sheeting.)

Here, I am clamping & weighing down the sheeting to the sides of the fuse after applying epoxy, to ensure a good bond. Also being a scuba diver, I found another use forthe ballast from my weight belt. It comes in handy keeping the top edge of the balsa sheet in contact with the fiberglass fuse sides that are too far from the bottom for my clamps to reach.

I put plastic wrap over the top so I don't accidentally glue my ballast to the side of the fuse. Otherwise, I can just see it now, "Gee, this planeflies like a brick!"