Wings

For the last few weeks, I have been immersed in the seemingly endless task of preparing the main ribs for the wings. There are a lot of ribs in the wings, over 50 of them actually, and each one needs some work and attention to some details before it can be riveted in place as part of the internal skeleton for the wing. They are formed at the factory in a big press and all the rivet holes are pre-punched in most of them, but the process leaves them warped and twisted to some extent, with rough edges all around. It has been a very boring, repetitious task that involves a number of tools. I do them in batches of a few at a time, to help keep my sanity and give me the feeling that I'm making progress. I remind myself how much money I'm saving. I try to get in some time each day on the project. Like most people, I have a lot of other stuff going on around here and I don't have all the time in the shop that I wish I had. Still, I have managed to put in anywhere from 1/2 hour to several hours per day on average. I probably spent more time on these ribs than some of the other guys do, but I don't see how I could have done it any easier. I did refine my techniques and get better as I went along. If I had to do it over again, I could probably do it in a lot less time overall. Here's my process:

Beginning with my die grinder and a 1" scotchbrite wheel, I deburr, or smooth, the large cutouts or lightening holes in the middle of each rib. I finally have this down to a science, and have been able to do the most recent ones much quicker than when I started. Then, It's off to the bench grinder which holds my 6" scotchbrite wheels for the next step, which is to deburr the edges of the flanges. The idea is to have a smooth, rounded metal edge when you're finished. I run all the edges over both wheels in 3 passes to get the inside of the flange at about 45 degrees, the edge at 90 degrees, and the outside at about 45 degrees. The third step is to bend the flanges slightly as needed to make sure they are at a right angle to the web of the rib. The flanges all need this fix. I haven't found one yet that doesn't. Finally, I use my fluting pliers to put flutes, or small creases in the rib's flange in between the rivet holes. This has the effect of "shrinking" the length of the metal flange, and it causes the rib to straighten out. It's really quite amazing to see. I work with each one until it will lay flat and has no warp or twist remaining, and the line of rivet holes is straight. If you over-flute and go too far, you can use the hand seamers to undo the flutes a bit, partially flattening about 3 of them at a time. It doesn't take much of a squeeze! Working this way, you can eventually get them flat and straight.

When they're all done, I will match-drill them to the spars, deburr the holes, and then they will be ready for cleaning, scuffing, and priming. Then, FINALLY, I will be ready to rivet the skeleton together. I can't wait. I'm learning that airplane building is 90% metal preparation, 10% or less riveting stuff together. You put in hours and hours of work and don't really have much to show for it. That's why I don't have a lot of pictures on this page. There's just not much to show. Then all of a sudden, the grunt-work is done and you can rivet something together and see your progress. That's when it's exciting.

Since there isn't much to see in this process, I haven't bothered taking any pictures at this point. But I will show you the end result of all this work when I get it finished. As boring as this is, I can see the end in sight. So I'm not doing anything else on the project until they are ALL done. Then... things will get real interesting. Stay tuned.

For the record and for the FAA, here is the log of my work over the last 3 weeks or so:

7-3-2007	Deburring, straightening, and fluting the ribs. Batches of a few at a time.	4.5 hrs.
7-4-2007	Deburring, straightening, and fluting the ribs. Batches of a few at a time.	1.5
7-5-2007	Deburring, straightening, and fluting the ribs. Batches of a few at a time.	1.5
7-8-2007	Deburring, straightening, and fluting the ribs. Batches of a few at a time.	5.5
7-13-2007	Deburring, straightening, and fluting the ribs. Batches of a few at a time.	1
7-16-2007	Deburring, straightening, and fluting the ribs. Batches of a few at a time.	2.5
7-17-2007	Deburring, straightening, and fluting the ribs. Batches of a few at a time.	3
7-19-2007	Deburring, straightening, and fluting the ribs. Batches of a few at a time.	1
7-20-2007	More of the same... finished the main wing ribs!	2
7-21-2007	Made template, drilled holes for conduit in left wing ribs, deburred holes	5
7-22-2007	Started deburring and fluting the tank ribs. Finished the tank ribs .	2.5
7-24-2007	Started deburring and fluting the leading edge ribs.	1.5
7-25-2007	More deburring and fluting the leading edge ribs.	0.5
7-27-2007	More deburring the leading edge ribs - finished deburring!	2
7-28-2007	Fluted final few ribs. ALL RIBS ARE NOW FINISHED!	1

Total: 39 hours

Here is the end result of all the work. It may not look like much but this pile of ribs is finally ready! There are twice as many ribs as you see here at first glance, because of how they nest together. What looks like a rib is actually a pair of them, a "right-handed" one and a "left-handed" one nested together. The tank ribs aren't in this picture, but they're ready, too. I just decided to bite it and get this work done with all of them at once.

Next, I can cleco these ribs to the main and rear spars for match-drilling. I will also have to figure out where to drill holes for the conduit for wiring, lights, pitot tube, etc.

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