Fuselage

MERRY CHRISTMAS 2009! It's a busy and festive holiday season and it's certainly been hectic around here. Just like most other folks, I suppose. But We're having a great holiday season. I hope you are, too.

It's great to have family and loved ones home for the holidays. My son Daniel is home from college, and my little granddaughter Maya is here, too. This is the first time they sat in the plane. It reminded me of how far I've come since last January, almost a year ago, when little Maya sat in the center section and I captured a priceless photo of her. It's the one you see near the bottom of my Home Page. That's why I joked about her being the "first passenger". Well, here she is again, with her uncle Daniel this time, actually inside the plane. Priceless.

Okay... anyway... over the last few days, I've managed to sneak in a little time now and then, to get this other gear leg weldment installed. After experiencing what a bear it was to install the left one, I was NOT looking forward to a struggle with the right one. But at the same time, I wanted to get it done. I was hoping this one would be easier. It wasn't. As I proceeded, it seemed that it would be even less likely that I would ever get this one in, so I was forced to look for answers.

I was dumbfounded why I was having so much trouble trying to get these weldments to go in, after taking such great care last May to make sure they went in smoothly, fit right, and gave me no trouble. What changed between then and now? Well, I finally figured it out. As I began installing the right one, it didn't want to go in either. I drilled out three nutplates on the F-704 spar flange and removed the cover bracket that is in the way. Still no luck. It just wouldn't go in. I was asking myself what was different last May, other than the fact that the fuselage wasn't riveted together? Well, here's the answer.

When I was doing the initial fitting and cutting out the opening hole in the bottom skin last May, the fuselage was upside down and the forward floor skin wasn't riveted on. Riveting things together wasn't the problem. The clincher was, I didn't have the FLOOR STIFFENER ANGLES put in place back then. The ends of the floor stiffeners, added later on, almost come in contact with the F-704 bulkhead web. I'll explain further and show some pictures.

See the red arrow above? It's pointing to the problem. The end of this floor stiffener angle sits on top of the spar's bottom flange and butts up against the spar. The stiffener is long enough that it almost touches the spar, so there wasn't enough space behind it to allow the flange on the weldment to fit in there. As obvious as this looks, it took me quite a while to find it. When you're wresting with one of these weldments, you're looking at numerous points of contact that it has with the fuselage. You're trying to line up bolt holes. You're trying to wiggle the thing down into place. It won't go. You wonder if the hole you cut in the bottom skin was big enough after all. You're getting mad and frustrated. You might be muttering some words you shouldn't be saying. You're bent over the side, and your back hurts. You're looking straight down on top of this thing. So you're not seeing it at the angle the camera shot this picture from. It's just not that obvious.

Here are some closeups. It's clear that if there isn't enough clearance behind this stiffener for the flange on the weldment to fit, you're going to have problems. So how do you trim the end of this stiffener? It's all riveted in place permanently. Well, I used my snips and just cut the vertical end of the stiffener off. Then I took a very thin little flat file and cleaned up the burrs and smoothed it out.

Once this stiffener was trimmed and left enough room, the weldment dropped right into place. Amazing. So how come my left one finally went in the other day without this trimming? It's because there was enough clearance behind that stiffener, but just barely. It was tight enough to give me problems but not enough to prevent the flange from slipping in there. If you're building an RV-7A and you are working on this area, make sure to trim these stiffeners before riveting it all together, and leave enough room for the gear leg weldment's flange to slide in behind this stiffener.

Once the weldment is fitted in place, the biggest challenge is to get a wrench down in between the F-704 spars so you can tighten the bolts. Here's the completed installation of both weldments, after the nutplates I had drilled out were riveted back on, the cover brackets put back on, and the bolts all torqued and most of them sealed. Yippee!

How do you tighten those nuts? Here's my high-tech solution to that problem. I just duct-taped my little wrench to this extension. The duct tape is strong enough to apply the proper torque on these nuts.

I only have two questions now. I'm wondering if these bolts are long enough. They do stick completely through the nuts as you can see, but not by much. I'm going to have to ask someone about this. Assuming this is okay, I'm wondering how I'm going to get some torque-seal applied here. There's no way I can reach down into this area. The torque-seal you see on the other nuts in there was applied before the two halves of the F-704 were put together.

Meanwhile, I decided to move on. I pulled out the fuel selector valve and installed it on the top plate for the cover, and clecoed it in place to see how it fits and how it looks.

Very nice! Now I'm looking forward to installing fuel lines and getting this thing hooked up. But I have a decision to make about an engine first. I've been mulling this over for a long time and talking to some friends and some experienced members of chapter 105. What does the engine choice have to do with fuel lines? Well, if I use a fuel-injected engine, I'm going to need a high-pressure fuel pump that goes inline right under this valve. If I use a more traditional carburated engine, however, I will only need a smaller booster pump further downline. I didn't realize at first that I would have engine considerations before going much further in the project. There are more reasons to choose an engine, too. Before I order my finishing kit, which is the last major kit that I need from Vans, I need to know what kind of engine I'll be hanging up front, because the finishing kit includes the engine mount. And there are several to choose from, depending on the engine you have. I'm leaning more toward a fuel-injected engine for several reasons. More to come on that subject soon.

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