Did some final prep before sheeting. Installed a few fittings and bolts that won't be easily accessible once the wing is sheeted. Masked off the landing gear retract gearbox to ensure I don't slop epoxy on it.
Laid out the sheeting and marked up the cuts and scarfs as required for the first few sheets.
The first sheet that went on is from the centre of the spar back to the trailing edge, from the root outwards towards the aileron. Fortunately these sheets are 50" x 50" rather than 48" x 48". The distance from the inboard edge of the root rib to the aileron bay is about 1 mm short of 50". This means one sheet can fill that entire space with about 1 mm to spare. It would be a real annoyance to have to scarf a joint for only 2" of sheeting to reach the aileron.
I had been messing around for the last few weeks trying to make a router jig to make the wing skins scarf joints. The skin is 2.5 mm thick so the scarf joints need to be 1.5 inches wide. Ideally, I would have used a router bit that was 1.5" diameter. I spent a lot of time trying to find a 1.5" router bit with a 1/4" shank. Had I found such a critter, I would have been able to secure a simple wedge mounted to my router that matched the slope of the scarf (15:1 or 3.8 degrees). I could have then run the router against a simple fence and made the scarf joint. Unfortunately it seems that no one makes bit larger than about 3/4" diameter for a 1/4" shank. If I had a router with a 1/2" shank there were lots of bits to choose from.
Since I only had a 3/4" bit, I tried to make a framed jig to run the router over the end of the skin and create a nice scarf joint. Unfortunately I couldn't get the jig to be stiff enough over the necessary span of 60". There ended up being too much flex in the jig and a router can do an amazing amount of cutting (or damage) in an instant. It doesn't take much flexing of the jig to ruin a 2.5 mm thick sheet. In the end, I decided I'll make my scarf joints by hand planing and sanding. The nice thing about scarfing plywood is the lines you get with each layer of ply. The lines act like elevation lines on a topographical map. The goal is to get them straight and evenly spaced.
I've numbered the sheets from 1 through 4 from the root to the tip. The wing section inboard of the aileron bay requires one and a half sheets to span the chord, so I've called those sheets Sheets 1 and 1+. Sheet 1 is the full sheet from the centre of the spar to the trailing edge. Sheet 1+ is the half sheet from the centre of the spar to the leading edge. Sheets 2 and 3 run from the leading edge to the aileron bay. Sheet 4 runs from the leading edge to the trailing edge outboard of the aileron.
I glued sheet 1 on place and then scarfed the necessary edge for sheets 1+ and both edges of sheet 2.