April 21, 2009

Fitted and Drilled F-713's, Auxiliary Longerons - 3.5 hrs.

Today I was able to finish installing the F-713 auxiliary longerons on both the left and right sides. Boy, this part of the project requires some mental gymnastics when you are studying the drawings and trying to figure out how things go together, because the drawings show everything oriented right-side-up, and I'm working on a fuselage that is upside down at the moment. It's hard enough figuring this stuff out sometimes, but then you have to turn it over in your mind, not mix up right and left sides, and if that wasn't enough, some these parts are oriented at an angle, which goes the other way when you turn it upside down. So I'm taking my time to make sure it's done right. I even tried just turning the drawings upside down, but that won't work either. It's just not as easy as it sounds. Nevertheless, I'm gettin' er done.

Fuzzy picture, but here they are, drilled and clecoed in place. Below is a shot from inside.

UPDATE: Another update from the future... if you have a sharp eye, you'll notice the gold clecos in the picture above. Yes, that's right. I drilled all of these holes 1/8" when they should have been #40 like the rest of the airplane.I did the same thing on the other side, too. Why did I do that? Well, there are a few #30 holes in the vicinity of the opening for the wing spar, and somehow in my mind I carried it on to this stiffener. Here's a lesson... once you drill a hole #30, there's NO going back to #40! So what do you do? Well, I ended up putting 1/8" rivets in all of these holes. Fortunately, the beefy stiffener under the skin right here took the larger countersinks quite nicely. I ended up installing 1/8" rivets and unless you have a really sharp eye, the end product is hardly noticeable. I've had at least one fellow builder admit to me that he did this, too. In the end, no harm done. The alternative would have been to buy new stiffeners from Vans, and worse yet, whole new side skins! I chose to leave it as is. Please... don't follow my example here.

I trimmed the forward and aft ends a bit to compensate for the angle of the longeron, and it needs a slight twist on the forward end to fit right, since the fuselage curves gently inward on the bottom forward end (at the top in this picture).

I spent the rest of the session trying to figure out what material I should use to make the little pair of F-719B angle brackets for the next pair of stiffeners to be installed below (er... actually, above... remember upside down) these longerons. The F-719's. You can barely see the horizontal row of pre-punched rivet holes where they go in the picture above. When I pulled the F-719's out, I discovered that I'm facing the same problem I had back when I put the firewall together. The ends that lap up over the F-704 bulkhead aren't made very well and the stiffener won't sit flat on the skin. I looked back to October 4, 2008 to remind myself how I worked with the problem back then. I'm going to have to deal with that all over again.

<< Previous | Home | Next >>

Contact me: swayze "at" europa.com (replace "at" with the @ sign... no spaces... you know the deal)