I'm just getting back into CL flying after a 40 year leave of absence and dragging my son in law along with me. I bought him Skyray 35 and an NIB 20FP for Christmas. I keep reading that the plane will be better with the plywood ribs replaced with balsa, but I'm afraid that having to fabricate them will scare him away. Hopefully, someone sells balsa replacements, but I can't seem to find them. Any help will surely be appreciated. Thanks , Stew
Make him a template (or series of templates) to cut them out with. I usually use two templates - one to cut the spar slots, and a second to cut the shape. Cut the slots first, then the shape, to avoid splitting the wood. They should be keyed with pins to line them up and keep them from slipping. It takes about 15 minutes to do a set for a Skyray once you set it up. You might need a 3rd template to cut the center-section ribs. I use a balsa stripper to cut down from regular to center section ribs - it takes some skill to keep it tangent to the surface but any mistakes are in the direction of cutting them too large, which can be sanded down. Leave the centers in the ribs, and use the pin holes to line up a stack for stack-sanding. Only then, cut our the leadout holes using sharpened brass tubing and an exacto knife. You can use a single template as long as you are careful cutting the spar slots - use a single-edged razor blade and a "chopping" action rather than a conventional cut to reduce the tendency to split.
The best reason to make if from balsa is not the flying (which, with the engines you are talking about, won't make much difference) but the durability. My plywood version converted itself to a pile of parts on the first crash, because it was so heavy that the wingtips just kept going when it hit, breaking every single part in the wing. The balsa version survived many crashes nose-in into dirt/grass, and only finally had to be rebuilt again after the Monokote got brittle to the point it cracked when I was wadding it up.
Laser-cut makes a lot of sense for a tapered wing but with all the ribs the same, it's much faster and quicker to do it with a template. Once you are done with the ribs, that's the only significant work to be done, cut the fuse and the doublers with a scroll saw.
Brett