Here's how the repair of the Junior Ringmaster was handled. Wingspan of this model is just under 32 inches.
As mentioned, EVERY sheet balsa rib was cracked or split in some way. Some of the ribs were knocked completely loose from the hardwood spar. First the ribs were hit with a small amount of woodworker's glue, especially those that needed re-gluing to the spar. Then, each rib received two hand-cut strips (about 3/8-inch wide) cut from 1/16-inch hard sheet scrap balsa. These were fitted as two diagonals on one side of each rib, using plenty of glue. Making them diagonal creates a kind of "plywood' effect to strengthen the rib. You can see them clearly in the near wing structure in the first photo. These had to be carefully located to avoid interfering with the lead-out wires running through the inboard wing. They were much easier to fit on the outboard side since there I could just sort of "slap them in".
A couple of months later, I had settled on white iron-on fabric as the covering of choice, even though I had never used anything like it before. Once I figured out the right setting for the iron, I found it really quite easy to use. You first tack it down around the edges, then seal it down really well all around. Finally, you go over the whole surface with the iron, which shrinks the fabric tight enough to smooth it all out nicely. The hardest part is where you have to pull it down over the wing tips. The last photo shows minor wrinkling that I never could quite work out on the inboard wing tip (it's complicated by the fact that you have to notch it around the control lead-out wires). But, that's a very minor flaw - it will be hardly visible after a couple coats of aluminum dope go on. So, I thought this went really well for my maiden voyage in using it, and I'll certainly use the same material on the Super Ringmaster to replace that brittle well-aged silk.
- Damaged ribs were repaired with small diagonal strips
cut from hard balsa sheet. Photo Copyright 2011 Larry Cottrill
- My first attempt ever at iron-on fabric wing covering.
Heat activates glue and shrinks fabric tight. Photo Copyright 2011 Larry Cottrill
- Some minor wrinkling of the fabric where it's notched around
control lead-outs. Not a serious problem. Photo Copyright 2011 Larry Cottrill