Thanks, Captain, good advice, but I wound up buying the 40 of them specified from Univair @ 200 bucks. Friendly A&P said to go by the book and that's what we'll do. The channels have to be of 61ST and have 1/16" radiused bend corners.
The rib channel used by Dakota would work, if you could buy it in lengths and cut to size, but making it up would cost you more than $5 apiece in labor.
What is surprising in my mind is how many of those channels were broken in my ship-- more than half of them. And every one of them were cracked or broken at the bends where they attach, on either end. I love the engineering and workmanship in those original Piper ribs. They are a miracle. But the channel braces are an engineering design defect, in other words, a bad idea. I noticed Piper changed the radius in the corners from 1/32 to 1/16--- meaning they were cracking with those tight radii.
Which reminds me: Surfing in that Northland CD is a great delight. Talk about a lot of work to put that thing together! And talk about how many reams and reams of documents can be put on one CD. It has the complete parts catalog for the PA-18, plus the L-21 assembly manual, plus all of the drawings, plus all of Northland's drawings, plus a big color picture of the Cub decal you can print out on photo paper, plus all kinds of other goodies. Only thing I can criticize about it is that it's not well indexed, and you have to do a lot of surfing to find what you're looking for. Changing the view from icons to details helps. I haven't yet found a good rendition of the PA-18-105SP wing with no flaps and trailing edge, but maybe one of the PA-18-95 might work.
I can see where most of the channel braces go, but not all of them.
