Thursday, September 11, 2008

When building progress is hard to see

When you're building an airplane, you go through many phases. There is a phase where motivation comes easy. When you're building a wing, or a flap, or a fuselage, you see fairly steady progress. At the end of your workday you close the garage or hangar door and look at your work and say, "gee, that's looking like an airplane, it won't be long before it's flying."

This is the same situation as a line at Disney World. Just when you think you're getting somewhere, you turn a corner and realize the line is way longer than you thought.

I am in one of those lines now. I am about to pass 1,800 hours of work on the RV-7A since I started in 2001. Even though the project is now at a hangar and not in the garage, I still work at least one hour a day on it, usually on the way home from work. I feel that I've put hours into the plane this year than any year so far.

But progress? Where's the progress?

I assume it's there... somewhere... but one cannot depend on it for motivation at this stage. Today, for example, I took the day off from work, and spent 7 hours at the hangar, mostly working on the canopy fairing. I've been working on this for several months now, and while I'm making some progress, I still have a long way to go, and I'm pretty sure it's not going to be as nice as I would have liked.

The windscreen fairing is simply the transition between the metal of the airplane skin and the curvature of the plexiglass canopy. Ideally, you want a nice, sleek radius (curve).

It involves laying up fiberglass and then sanding in the the radius and then slowly sanding away fiberglass. A line of tape marks the top edge of the fiberglass so there, too, it needs to be carefully sanded to a razor-thin edge.

Today, I sanded some more, down to 150 grit, and started filling in the pinholes and rough spots by spreading more epoxy.

There are two small aluminum clips that I used to hold the canopy in place. They come through when I sand the fiberglass down (you can see them in the photo below). I'll get them covered, but this presents a bit of a "ski jump" look to the radius. Looking back, I think I should have cut the canopy back farther when I was cutting it -- cutting it back right to the point at which the vertical portion begins.

There's another transition on the side of the canopy that I haven't been paying that much attention to. Here, there isn't a radius, it's a smooth curve around to the side, and then a feathered bit of fiberglass to the side aluminum skirts. You can probably see here that right now there's just a bunch of fiberglass layed up here. More sanding is required, but I've got time.

While I let the epoxy cure (at least 24 hours), there was plenty of other work to do. I'm putting the fresh air ventilation system into the cabin. It needed a dumb, little bracket made out of .032 aluminum angle. Nothing hard, it just took a few hours more than I'd planned. And because I lowered the instrument panel by 1/8", some of the predrilled holes in the instrument panel didn't help me much here.

And that's one of the interesting things about building an RV airplane, everything has an effect downstream. A small change made here, affects a part you work on later, and another, and another, and another.

But I muddle on, even though I'm not at the stage where I can turn around and say, "wow, I'm moving right along, this thing will be flying soon."

It won't be flying soon, but we airplane builders plug along anyway.

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