On another note, I took a couple of pics from my camera phone the other day of the EAA B-17 Aluminum Overcast. They managed to get the new control surfaces installed, inspected, and test flown early last week and it was flying folks around town all weekend. Flew within a half mile of my house several times. The thing that gets me the most everytime is that there is absolutely no mistaking the sound of the wright-cyclone engines purring away as the plane lumbers through the sky. I could even hear it way off in the distance. There is also no other airplane with that distinctive look in the air, with its huge curved tail sticking way above the fuselage. True beauty in the air in my opinion. I find it hard to imagine that this was built as a war bird.
Anyway, here are some pics of the leading edge ribs. There are 6 on each wing. 2 of the ribs are positioned about mid wing where the joint between the fuel tank rib and the leading edge rib of the wing are basically side by side. The two LE ribs on the ends have no holes predrilled in the flanges, so I am not going to flute or straighten these until the time comes to fit them together with the fuel tank. Holes will be drilled for nut plates that will secure a strip of aluminum in between the inboard LE rib and the outboard fuel tank rib, as well as the skins that fit over both of these ribs, and until I know where the holes will be located I cannot flute the flanges yet.
And here is a pic with the two LE end ribs without the holes in the flanges sitting on top of the other ribs. I will finish these up later.
Some interesting notes about deburring and fluting these ribs. Deburring using the scotch brite wheel was not too bacd, but you have to be careful when deburring the many cutouts that form the very tip of the leading eade of each rib. The instructions also warn you to make sure that you remove an bumps in between adn around these cutouts to ensure that the skins will fit properly. I had to smooth over a couple of the separations by making several passes with the wheel until I was satisfied that the nose of each rib was rounded and smooth. So the deburring was not so bad, and that went fairly quick. Fluting, on the other hand was a bit more challenging that on the main ribs. The curved surfaces of the nose rib required several more flutes, and I had to go back and reflute a few times after I had straightened the flanges.
Straightening the flanges presented some additional challenges. The instructions say to use a hand seamer, and I can see where in some places this may be preferable to even using my handy dandy flange straightening tool the reason is that there a many rib hole stiffener flanges and impressions that tend to interfere with the straightening tool, not to mention that the straight edge of the tool is not conducive to curved flange areas such as the nose portion of each rib. Neither is a hand seamer for that matter. SO, I ended up using the tool where I thought I could to straighten most of the flanges, and then used a small rubber mallet - the one that comes with 2 tips that you find at most hardware stores. One side is a red-eraser-like rubber, and the other side has a plastic tip.
Use the rubber side of the hammer, laying it flat on the bench surface. Place your finger up against the inside edge of each flange to act as a kind of soft support block for the flange, and swing the mallet against the flange lightly until you start to feel the metal give a little bit. Then check it with a straight edge and adjust as necessary. Once you have practiced this a few times you will start to get a feel for when the metal is bending, as well as when it "feels" that it is straight. be careful on the nose sections of each rib when doing this procedure. They are very small and it is very easy to over bend them if you are not careful. A couple of light wacks with the mallet is all it takes to straighten this area of each nose rib.
Once I was done straightening the flanges, I rechecked the holes in each flange for proper alignment, and re-fluted or added new flutes and re-straightened again as necessary. Again, quality time spent here makes all the difference for ending up with a well fitting LE rib-to-skin assembly. If there are any questions about this then I simply refer you to the EAA Hints for Homebuilders video section on their website. That is where I learned how to use the mallet technique - on one of the 6 episodes of rib forming videos.
Now I just have the fuel tank ribs and some minor deburring to do on the rest of the ribs and I will be ready to scuff, clean, and prime them all. The funny part is that I think Ron Duren was also chasing this same activity during a similar time frame a couple of years ago, ebcause I remember reading his post about trying to get it all done before going tp Oshkosh. I am in the same boat right now. Funny how that works.
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