I got the curve bent in the right side longeron today. It is a very iterative process.
I marked the longeron every 1" in the bend zone and marched through it. The first iteration didn't fit very well. I needed more bend close to the straight sections on both ends and less in the middle. I think the way to do this is to ease into it from one end correctly as you go. Every time I tried to fix one thing I made something else worse. With lots of iterations I finally got it. I thinking making one change at a time is key also. We'll see if I learned anything when I do the left side.