Monday, January 31, 2011

I'll leave the tip

Well, part of it anyway.

It's the day before what is predicted to be an epic ice storm here in Columbus, but you wouldn't have guessed it from today's weather. The first blue sky for as long as i can remember and a pleasant 32 degrees. Perfect for heading to the hangar right after work. I'm ready to put on the left wing's wing tip.

The wing tip on the RV-12 is a cleverly crafted collection of intricately shaped aluminum parts that are assembled into a wing tip whose feature list starts and stops at "pragmatic." It's easy to assemble and strictly utilitarian. Note the absence of "aerodynamically sophisticated" and "aesthetically appealing," for it is neither of those.

As an example of the cleverness of the design, consider the hand hold that is molded into the wing tip to provide a good grip when moving the wings around. Remember, they're designed to be removable, and given the cost of dropping one, it's nice to be able to get a good grip on them. This little part doesn't look like much, but watch how easily it gets converted into a hand hold.

Two simple (almost) 90 degree bends later:

Then, just because Van's likes to introduce some suspense to every story, it gets set aside while we rivet in a little tip rib.

Once your attention is diverted, here comes the big, shocking plot twist! It gets clecoed into place.

Hmm. It still doesn't look like much. It needs a little more plot development. Unfortunately, that requires work on the bottom of the wing. I need a helper to flip the wing, but when the airport is as deserted as it was today, there's no one standing around that I can enlist as an aid. That leaves the not-so-fun method:

See that little sliver of exposed belly? Well, there's another little sliver of exposed back on the other side, and it's pressed against the cold plastic of the creeper. Brrrr!

I'm under there to cleco on the bottom skin of the wing tip.

I had to roll around on the creeper to do the riveting, too. My new riveter has been giving me trouble - it starts to do a "soft" pull where it seems to be having trouble getting a good grip on the rivet's mandrel. Then it starts refusing to spit out the pulled mandrels. That means it's time to take the silver nose cover off and tighten up the assembly inside there.

I can't seem to get it tight enough to stay together because it would require a thin wrench to get a good grip on the back cylinder. The nice replacement parts kit that came with it had such a wrench in it, but because it was such a nice replacement parts kit, I put it away somewhere where it wouldn't get lost. Which, of course, means that I now have absolutely no idea where I put it.

I put on the front half of the top skin. That was a real chore because as soon as I removed all of the clecos that were holding the top skin to the outermost rib, that rib did what it does every time I remove the clecos: it jumped way out of alignment. That's probably an indication of bad fluting. I had to corral it back into place with more clecos.

At that point I would have put on the last top wing tip skin, but I couldn't find it. Sure enough, I had left the top aft tips back home in the basement. On the plus side, that meant that they will be nice and warm, thus making the removal of the blue plastic much easier. On the minus side, it means you won't get to see the big finish where the cleverness of the design of the hand hold becomes apparent.

For now, here's a teaser:

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