Dave’s RV-7A Building Log

Primed the tank attach Z brackets for the left wing.

Since they need to dry overnight, I moved on to the tank stiffeners. Might as well do them all, left and right. I did the rough cuts with the band saw, cleaned them up with the belt sander, and did a final smoothing on all sides with the Scotch-brite wheel. A little deburring and they are set to go.

I started to put the tank ribs in place. Those things are going to be tough. You really have to push on them to get the holes to line up. I’m going to leave that for tomorrow.

I wasn’t happy with the way the first Z-bracket turned out after back-drilling it through the spar. One of the holes in the spar ended up slightly elongated. Instead I went a different route. For each bracket, I lined it up with a bolt through the middle hole and squared it to the spar. I then marked the location of the other two holes with a marker. I then drilled them on the drill press. With the center line already marked, it was pretty easy. For me, it was easier then back-drilling through the spar. I checked each one and they are lined up perfectly.

I then deburred all of the holes. Next was doing the nut plate drilling: bolt on the nut plate, make it straight drill one side hole to #40, cleco, and then drill the other hole. Nut plates are so much fun. After that, I countersunk all of the side holes.

I think I’m going to prime the brackets before putting on the nut plates, but not tonight. Instead, I pulled out the tank ribs. I had already squared up the flanges to 90 degrees, but never fluted them. Now’s the time. Grab a beer, crank up the tunes, and dive in. I fluted all the tank ribs for left and right. And just to finish up the fluting for good, I did the funky inboard rib for the right leading edge. All ribs are now fluted!!! I’m glad that’s behind me. One big priming session on the right wing ribs and the right wing will be ready to put together. I’m glad I did all of the prep work for both wings together.

The last thing I did was to pull out the right tank skin and put in the cradle. All ready for assembly.

Adele tagged along for my lesson today. I wasn’t sure if she was going to like flying in a small plane. She loved it, even though it was a spam can. It’s cloudy here often, but when it’s clear it is amazing. All of these pictures were taken by Adele from the back seat. She was snapping pictures like crazy–40 in all. The pictures are:
Elliot Bay with downtown Seattle on the far right
Blake Island–the entire island is a state park
Olympic Mountains
Self portrait
Mount Rainier
Mount Rainier again framed by the window and wing

Didn’t do too much tonight. I drilled the center hole in each Z bracket. I bolted one on the spar and drilled the two side holes. Decided to call it a night after that.

After Steve left, I started the first steps on the fuel tanks. I cleaned up the Z brackets on the Scotch-brite wheel.

I decided to follow the DanC method of fuel tank placement. It seems much more accurate to me. It might be more work to take the leading edge and tank on and off, but I don’t think it will be easy to use Van’s instructions either. Elongating the holes in the brackets in order to make the fuel tank sit right next to the leading edge will require some on and off of the tank as well.

I think I’m following Dan’s instructions correctly. I marked a line on one side of each bracket that is 1/16″ toward the bracket web from the center line. It makes sense. That will move the bracket over slightly, so that the pop rivets on the other side of the bracket will have more clearance. My pop riveter from Cleaveland has a huge head on it. I’ll have to find a riveter with a smaller head on it.

I also set aside one of the Z brackets as the inboard bracket. That one is different from all of the others. On that one, I put the line 1/16″ away from the web. In this picture, you can see how the centerline is slightly offset up or down.

This little edge marker tool is very handy. I got it from Avery or Cleaveland.

My friend Steve stopped by to help out. He final drilled the left wing leading edge. I fluted the funky inboard rib and marked a line on the joint plate. Getting those two things lined up was a hassle, but we finally got it just right and drilled.

I also temporarily put the bottom skin back on in order to mark the tie down location. It’s about 1/8″ from the pre-drilled hole. I don’t really trust my marks, so I’ll drill that out in steps to make sure it’s centered. It’s not super critical, since it’s on the bottom of the wing.

Somewhere along the way, I added supports for the trailing edge of the wing. I just put a screw through a block of wood, through the tooling hole, and then into the support. You’ll notice I left clearance for the skin overhand. On the top support, this shot shows the bracket that is bolted to the wing. And if you look carefully you can see I had to cut a small notch in the upper support arm for the skin.

This shot shows the root end of the wing stand. Amazingly, I didn’t need any shims to correct twist in the wing. It was right on. I did put a piece of cardboard between the spar and support just to reduce marring.

Ignore what I said before about the clecos. You need a lot more for the leading edge and tank while the top skin is still clecoed on. I’ve been scavenging clecos from the top skin. I might break down and buy another hundred. I don’t want to waste any more time moving clecos around.

Built the leading edge form using the plywood from the wing crate. While I had the saws out, I also cut the plywood for the wing cradle.

I put the leading edge skin into the form and clecoed in the ribs. Not an easy task. The Orndorff video shows clecoing together the leading edge on the wing using big straps. Not sure if that is an old way or just an alternate way.

After clecoing together the leading edge, I put it onto the spar and clecoed the two parts together. Looks very cool.

Work on the joint plate is coming up, so I looked around for it. It’s the AS3-032 X 1-1/2 X 36-1/2 strips. The only place this is specified is on the packing list.

The inner most leading edge rib is not pre-drilled, so I didn’t flute it yet. I marked on the rib approximately where the holes will go, so now I can flute it.

Clecoed on the top skins and wing walk doubler. Drilled, moved the clecos, and drilled the remaining holes. I also removed the bottom skins in preparation for working on the leading edge. I didn’t feel like getting the saw out to make the leading edge cradle, so I studies the instructions and plans for a while. Had some company out in the shop tonight.

I discovered how far 400 clecos will go. The Cleaveland RV Tool Kit came with 300 3/32″ fasteners, and I bought 100 more. The instructions say to cleco on the skins for drilling at every fourth hole. I did every third hole just to be an over achiever. 400 clecos was about 40 shy of doing both the top and bottom skins of one wing. Since you don’t need the top and bottom skins clecoed on at the same time, 300 would have been plenty. Now if you want to be a super over achiever and cleco every other hole, you’ll need more than 300 clecos.

After spending the weekend in Portland, I was able to do a few things when we got back on Sunday afternoon. All the way driving down and back, I kept thinking about how it would be a one hour flight in an RV-7 rather than a boring 3 hour drive.

I decided to move the wing stand a bit. Kind of a hassle, since I already had the wing all perfectly straight. However, I don’t think there was enough room between the post and the wing at the root end. I put the bracket on the outside of the post at that end instead of the inside. I was kind of limited in where I could put the posts, because of the rafter spacing. But then a brilliant thought hit me (well, at least a useful thought). I figured out that I could put the wing stand on a diagonal and put the posts wherever I want. So I put them 114″ inches apart as suggested in the plans, put the wing back on the stand, and got it all straight. Getting it straight the second time was much easier for some reason. This shows the free access to the inner-most rib.

I drilled the holes in the wing walk doubler.

I also clecoed on the bottom skins, drilled, moved the clecos, and drilled the remaining holes.

The left wing is now in the stand. This feels like a huge step.

First I re-examined the riveting on the front spar from last night. There were two more rivets that I wasn’t happy with. I drilled those out, and then re-riveted. I realized that I was using too high of a pressure with the rivet gun last night. That might have been part of the problem.

With the front spar done, I moved on to the rear spar. To keep myself from making stupid mistakes (that I’ve made before), I marked the holes to leave empty with masking tape. These holes are used later to rivet on the flap brace or aileron gap fairing.

This shows the finished product. One note to watch for: check the rivet lengths. I found that the -8 rivets that the drawings called for at the root end were not long enough. I went with -9 and they worked great.

Drilled two holes in the outboard-most rib to attach a short piece of angle that attaches to the wing stand brace. This sound complicated, but it’s really quite simple. I should have taken a picture. The root end just gets clamped on. Used a laser level on a row of holes on the front spar to determine how much to jack up the middle. A string would have worked fine, but a laser is more fun.

Hung a plumb bob off of a cleco at the root and outboard end to make sure there was no twist in the wing.

Put a few shims under one side to even it up. There is less than 1/32″ twist along the ten foot span.

I pulled out the skins and placed them in their proper positions. Started to cleco on one skin, but I’m beat. I’ll leave that for later. Plus, I should put some braces on the bottom of the stand to hole the rear spar secure.