4 months. Thats how long it has been since I have done any major work on the RV-7. Between work and family and then holidays, I really haven’t had much free time to get down to the shop and build. Having some time off for the holidays, I decided to put work and learning aside for a few nights while I am off and get some work done on my build. I only have a few ribs left to straighten and then flute, and they were the leading edge ribs.
These guys were a bit more tricky because of the curve on the leading edge, and I had to refactor my flange straightening tool so that it had a smaller “bite” to allow me to not mess up the very nice and sleek compound curve in the top of the leading edge. You can see how much smaller the anvil is on my flange bender in this photo:
In the bottom left of that photo, you will see the new anvil I cut from some spare oak I had left over from the first, wider, anvil. This worked great, and didn’t cause any warping or mis-shaping on the top curve. I did all the rib straightening down in the shop on my bench, and then moved my stack of ribs upstairs so I could use my wifes granite counter tops as a perfectly flat surface to do my fluting to bring the ribs back into flat.
Heres my finished stack of leading edge ribs, with their perfectly 90 degree flanges, ready for fluting. Notice how much warping there is from the forming process. This is why we flute the ribs:
And after about an hour and a half of fluting, I ended up with a nice flat stack of leading edge ribs.
Some needed a bit more than others, but they are much straighter and flatter now. I might have to do a little more here and there once I start mounting them on the spars, but I’d say I was able to get them 99% of the way ready. FINALLY I have all my ribs done. All the flanges are at 90 degrees, and they are all fluted to be as true as possible. This was probably the most boring work I have done so far, and I am SOO SOO glad I can move on to something else. Heres all the photos from tonights session in one album:
Google Photos Link: https://photos.app.goo.gl/0DF6VPiHYHkbKkjQ2
Hours Worked: 3.25
About a week ago, I decided to bring my wing ribs upstairs and do the fluting up here, since that doesn’t produce any filings or shavings. HOWEVER….I have had a lot going on family wise that I haven’t been able to spend much time on them. I’ll also admit that over the last few days I have actually been fiddling with these things to the point of frustration. I tried a few times to sit down and get the straight using the wood dining room table as my “flat surface”, and always end up frustrated because no matter what I tried, they never would come out straight.
You see, we have to flute the flanges on the ribs because during the forming process they will get bowed a bit. Fluting “shrinks” the metal down along the flange, pulling it back straight. See how they are from the factory:
It seems like a simple process, and it actually is…..if your reference surface is truly flat. 😐 Turns out, our dining room table is not exactly flat, and I was using this bowed/curved surface as my guide and my ribs never came out right. Once I realized this, thanks to my wife Tammy, I decided to use our granite counter tops, since I knew they’d be nice and flat. After switching over to the stone counters, I ended up using the “table top” method of rib fluting. This video shows how to do this method: https://www.youtube.com/watch?v=pIvFpVV6kIQ
The results speak for themselves. After I did the table top method, with the flanges sticking up I flipped the rib over with the flanges down towards the counter top to double check. Then I used a metal ruler to measure that the rivet holes were all in alignment. Some ribs (like the one below) only needed a couple of flutes, while others needed many more.
I ended up getting the process down pat, and was able to knock out 14 ribs using the granite counter to and “table top” fluting method. I did have to go back and re-do the ribs that I did on the dining room table, since they were not straight. I’ve got a lot more to go, but I think this method will help me knock them out quickly. Here’s all the photos from tonight’s work:
Google Photos Link: https://goo.gl/photos/pc9q3jqyrzesHnzn9
Hours Worked: 2.75