I assume that you'll be using the full sheeting back to where he recomends?

A quick check showed me that he has a DXF file available at....

http://www.charlesriverrc.org/articl...egrolite2m.htm

Load that up into some sort of CAD and scale it to your needs. Print it out and glue the paper to the plywood. Trim sand to split the line and make two. Cut the balsa ribs using a template and knife and then stack all the blanks between the templates. Sand the excess to match the ply templates and cut the spar slots while all the ribs are in the stack so the slots all line up. Trim carefully for a nice spar fit.

If it's tapers then make the templates and stack a whole lotta rectangles between the ply 'plates using long #8 bolts again to hold it all together. Carve and sand to form a block of ribs. Do two sets, one for each wing. For sharply tapered panels you'll want to sand the bevels off slightly afterwards.

Another trick, sand the wing sheeting before you put it on. That prevents the balsa sagging between the ribs under the pressure. With care you can keep any errors to less than 1%.

Don't forget the leading edge template for that part of the job. It's probably the most important task. I think Marc has some flat segment carving tricks to rough out a faceted shape that pretty much guarantees a decent leading edge shape once sanded smooth.