Sunday, April 11, 2010

Capital Management

There are myriad challenges inherent in the undertaking of a long-term project like building an airplane and one of the larger is the management of various pools of capital. Money comes to mind immediately as a potentially scarce resource to be spent with care, but there are other less tangible but equally important accounts that require constant attention. One of those is the responsible expenditure of familial capital.

Never heard of it? Familial capital is the account in which you deposit and withdraw the patience, tolerance, and contributed assistance from your family. It is not completely unheard of for a builder to have to quit the project because the family is just sick of it. While it certainly helps to have a single-minded, all-encompassing passion for the project, it can easily be over done.

"Sorry, Honey, I can't make it for your birthday party, I'm in the middle of bending longerons."

Precisely how many times do you think you can get away with that?

The familial capital account has a group of accounting cost centers against which funds can be withdrawn, and one of those is the "Hey, can you give you a hand, Dad?" cost code. I mention this because I was faced with a tough decision today: draw on the account first thing this morning to get help with mowing the lawn, or save some lucre for later.

I went with the lawn mowing. If Co-pilot Egg does the bulk of the mowing (I do the edges and the heavily sloped side yard), I can do the weed whacking while she mows and have the entire job done in less than two hours. She, unfortunately, doesn't like or want to mow, so it's a pretty dear expenditure. I suppose her recalcitrance is normal; I always say that if mowing was fun and people wanted to do it, there'd be a three hour queue for the "Mow Mickey's Yard" attraction at Disney World.

There is not such a queue, nor is there even such an attraction. That speaks volumes for the lack of popularity of mowing.

So, mowing done and daughter off to greener pastures (so to speak), I had no one to help me cleco the fuselage side skins to the fuselage center section to aid in positioning a couple of small parts. It's not that the skins are heavy, it's just that they're large, unwieldy, and hard to hold in position while the clecos are put in place. Also, I really didn't want the skin to be unsupported - that causes it to bend in mysterious and potentially damaging ways, putting odd torques and stresses on the skin and the bulkheads it is attached to. After a number of nearly pornographic contortions and most assuredly pornographic utterances, I got the skins clecoed into place and supported with clamps. With only two hands, too! Amazing, right?

This was another of those cases where the drawing in the manual could be considered a vague hint at best, but with enough diddling around I think I got the parts where they're supposed to be. This view is looking down into the center section, which itself is upside-down on the sawhorses. Which explains why the 'L' is on the right, right? The wider portion of the part (the right side in the picture) points towards what will be the front of the airplane. After all of this effort, it's slightly disappointing to learn that the function of this part in the overall scheme is somewhat minimal: it merely stiffens the fuselage skin in the area between the two bulkheads.

That's one of those jobs that's not exactly infused with fame and glory, but I suppose someone has to do it.

Unsurprisingly, immediately after wiping your brow in relief at having that done, you get to do it again for the other side. Ah, the curse of symmetry!

The reason for all of this tomfoolery is to match-drill the holes for the little braces into the center section so that they can be riveted into place. As you may remember, I've had my fill of drilling holes into the center section, but just to make it even more fun, these particular holes have the added bonus of being hard to get at.

I know, I know. If it was fun, people would be standing in line for the "Match Drill #30, 72 Places, Mickey's Center Section" ride.

I figured there were two ways to do it: use the super-long #30 drill bit, or take the whole thing apart and take it to the hangar and try the angle drill. I don't like the super-long bit because it wobbles, and as I learned on a couple of holes on the center section a wobbling bit elongates the hole that you're match drilling through. I arrived at a compromise: I'd use the long bit to get the holes started, take everything apart, and go to the hangar to finish the drilling with the smaller air drill. And it would have worked, too, if not for the fact that the angle drill would only fit the two holes in the middle of each side. I had to bring it all back to the basement to finish up the remaining four holes with the long bit.

After that, it was a bit of a relief to find that the match-drilled holes, well, matched. They don't, always. To be perfectly honest, only seven out of the eight matched this time; the eighth needed just a little reminding from the long bit.

The brackets get riveted in with pop rivets, which is nice, but as I was driving home from the hangar I got to thinking that it was odd that the same rivets I've been using for attaching thin parts to other thin parts would be used to attach these thin parts to relatively thick parts. There's only so much rivet to go around, after all.

It's good that I thought about it! Rather than just reaching for eight of the 12,500 trusty LP4-3 rivets included with the kit, I decided to actually read the directions. Unsurprisingly, they dictate the use of LP4-4 rivets instead of the normal LP4-3. Ah, the required rivets are 33% longer. Makes sense!

And matching that unsurprisingliness is something equally surprising: they went in easily. I was afraid that they'd be too close to the edges of the center section for the rivet puller to get at them, but such was not the case.

Hmm, an unplanned withdrawal from my Good Luck account. Hope I don't need it later!

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