9/11/2008

DISASTER STRIKES!!!

I took some wing ribs to my EAA chapter meeting last night. I talked with one member at the beginning of the meeting, and he questioned the grain structure of the particular wood I was using. (He was familiar with Sitka Spruce, but I was using Douglas Fir.) To his eyes, it looked like there was too much grain "runout", meaning that the wood grain had too much "slope" to it. I sat through the rest of the meeting feeling nauseated and apprehensive. Was it really true? Were all of my ribs like this? Would I have to start all over again?

It turns out that we had several guests at this meeting. One of those guests just happened to be an A&P (Airframe and Powerplant) mechanic who specilizes in antique aircraft restoration. Perfect! (Antique aircraft use a lot of wood, so it sounded like he would be the perfect guy to ask about my dilemma.) So, after the meeting ended, I went up and introduced myself, and told him about the project that I was working on. I also mentioned that I just happened to have brought a couple of wing ribs with me, and asked him if he would mind taking a look at them.
He didn't mind at all! Cool!

Unfortunately however, he had the same misgivings about the wood grain that the first guy had. Even though my grain runout was within spec (more or less), apparently there needs to be at least one continuous "grain" from one end of the piece to the other (and preferably more). Otherwise, there's a potential weak spot where that piece could split (which it would do between the "grains"). Of course, it made perfect sense when he explained it to me that way.
I was just bummed that I had done it all wrong. He said I could try to replace the defective pieces, but some of the defects are in the top and/or bottom of the ribs, which would be very difficult to replace. Another option would be to "shore up" the weak spots, but that would be adding unnecessary weight, and he recommended against that. And lastly, as if to add insult to injury, apparently the "aircraft grade" plywood I had used wasn't good enough, either. It had too few plies. So, it really did look like I would have to build the ribs all over again.
What a bummer!!!

At this point, I had about 200 hours of work invested in the wing, and another 100 hours in the empennage. For all I knew, they were inadequately built, as well. Over 300 hours (and almost 7 months) of work down the drain. It really did look like I was going to have to start over!

SOUL SEARCHING

Every once in a while, I get this feeling that I might be in over my head, and that it really would be better to start of with a kit, or at least a solid set of plans to work from, rather than trying to make it up as I went along. In the light of the recent developments, I reasoned that if I really was going to start over again, this would be a good opportunity to pick a different design. I even spent some time reviewing all the options in the current kitplane market. (Zenith just announced the new and improved Zodiac CH 650 this year at Oshkosh, and it looked really cool, too!) But, as I kept looking back at pictures of Piper Colts and Vagabonds, I realized that's the type of plane I really have my heart set on. Besides, once you start on a project, you're supposed to finish it (or people look at you funny). So, with a heavy sigh and a new resolve, I'm going "back to the drawing board" (so to speak) to come up with a new plan.

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