Main spar.
The main forward spar is cut into the wing from the bottom. I first cut a 1/4" trench then with sanding blocks I sand it to the 3/8" diameter.
A template is cut first out of some 3/32" balsa, then the spar is cut from 3/8" 7 ply birch.
after dry fitting the area is masked off with blue tape and the trench is filled with gorilla glue. A small brush spreads the glue to all the walls.
The spar is moistened with water to kick off the gorilla glue. within minuets the glue starts to foam out.
I will let this dry for a few hours before I sand it flush with the bottom of the wing.
On to the rear spar.
TB