I have set myself a little mini project. Amongst all of the pieces required for the centre section, the ribs are going to be critical. There is four. Only two attach directly to the front and rear spars, so I am taking extra care with these two big 1 1/4″ wide ribs. They will be what sets the correct sizes and squareness of the whole centre section.
Step 1: After cutting the ply sides and routing the capstrip, I glued the front and rear sections for each rib against a completely square external frame. This makes sure the faces and lengths are exactly correct. I used the edge of the table to make the centreline square. Clamped, glued the spruce blocks, clamped them and removed the frame so it didn’t stick.
When I get started….it gets messy in here. Its going to be tight in the plane factory later on when I get to the wings!!
Step 2: Glue in the capstrip and reinforcing spruce
Step 3: Once dried, I then sealed the inside of each of the ply pieces and capstrip that is exposed. Picture below is the completed glueing, masking and one coat on internal surface
Step 4: I have drilled breathing holes in each of the rib sections. There is only holes on the outboard sides of each rib. You can see them in the picture above
Step 5: Glue the remaining outside piece of ply, sand and seal the outside faces of the ribs,with the exception of the faces contacting the spar and spar attach brackets
Note the cutouts and drill holes to attach to aluminium on the outboard ribs will be drilled when in place.