Tail block

Run a straight edge down the hinge line of the fin, crossing the rear of the fuse. Draw a line and cut this part off (I use a coping saw). make sure you cut outside of the line, and watch both sides carefully as you cut.

Now take a sanding block and true up the rear of the fuse to match the hinge line of the fin.

Gluse a piece of 1/2" light balsa block to a piece of 1" light balsa block. This is what we'll make the tail block from. (measure the length from F-9 to the hinge line and make it slightly longer and slightly wider than the fuse.

After this is COMPLETELY dry, lay the block in position with the 1/2" block against the fuse. Sand the front of the block so it sits flush at the front with no gaps.

Now take a sharpie and mark all the way around here where the block meets the fuse, everything.

Roughly shape the outside of the block with a carving knife (don't try to get too close yet).

I take a router blade on my X-acto knife and hollow out the block. It's not much weight, but it's useless weight so it has to go. You can just leave it solid if you have a really light block of wood.

Now glue and tape this block into position using polyurethane glue.

let this dry overnight, and then sand to final shape.