Dave’s RV-7A Building Log

Julie was busy working on the computer, so I attempted solo riveting. Time to get those wing ribs attached to the main spar. It’s fairly difficult to keep pressure on the rivet gun, keep it straight up and down, and watch the bucking bar. I did surprisingly well. I got through about 75% of the rivets with only one smilied rivet head. And then things got worse. I ended up drilling out about 8 rivets, and I might still drill out a few more. Julie popped out and helped buck some of the redone rivets (after she heard some aircraft building vocabulary emanating from the garage). It was much easier having help.

I know some people clamp the spar to a workbench. I found that this orientation worked pretty well. I could push down on the rivet gun from the top (remember: manufactured head on the thin side, e.g. the rib flange).

Here’s one row that turned out perfect.

One small piece of advice: start at the outboard end of the spar. Those ribs are much easier. As you move toward the root, the spar reinforcement gets in the way and there’s not much room to work around the wing walk doubler ribs. Hopefully by the time you get to the tough ribs, you will be good at it.

Went down to the Mount Rainier EAA 326 chapter meeting in Puyallup. Great group, and lots of RV builders. After the meeting, a few of us mosied over to a nearby hangar to check out Gordy’s RV-7. It was great to check out another project, especially one that is so far along.

Drilled the leading edge ribs to the main spar, deburred.

Reading the instructions a few days back, I couldn’t figure out if the leading edge ribs should be drilled at this time or not. I figured it wouldn’t hurt, and they would be much easier to drill with the main ribs removed.

Placed rivets in the main ribs to main spar, all ready to rivet. Some of those rivets are a very tight fit. Had to remove some of the clecos to make them go in. Now I’m really ready to rivet. Honest.

Moved the wing stand posts a little further apart, so that the skins will be accessible from both sides. Completed the cross braces. Clecoed the main ribs to the left main spar. Ready for riveting. Just waiting for a dance partner. Read ahead a few pages in the instructions, underlining the steps that need to be done.

Cleaned, etched, and primed the left main ribs. Getting close to the last step on those ribs.

Marked the wiring conduit location on the right main ribs, drilled a pilot hole, and used the Unibit to enlarge it to 3/4″.

Ordered the Gretz Aero heated pitot mount. The Dynon pitot installation manual says to use the mount for the PH502-12CR pitot. According to the Gretz web site, this pitot was formerly known as AN5812-12. The mount kit is $108 direct from Gretz or $104 from Aircraft Spruce. I ordered it from ACS.

I followed Van’s suggestion for the wiring conduit location. I drilled a 3/4″ hole below and aft of the large lightening hole in each of the left main ribs. I also enlarged the front lower tooling hole to 1/2″ for snap bushings in the first 10 ribs from the root. My plan is to put the wing tip wiring (position light, strobe light, landing light, maybe antenna wire) in the conduit, and extra pitot stuff (pitot heat wire, AOA tube, possibly static air tube) in the snap bushings.

I was a little nervous drilling big holes in the main ribs, but they came out nicely. I used a cardboard template to mark the hole on each of the ribs, drilled #40, enlarged to 3/4″ with the Unibit, and deburred.

I also deburred all of the spar attach holes in the ribs. I think these ribs are ready for priming!

I noticed that the flanges on some of the ribs seem to no longer be at 90 degrees to the web. The bend seems to have relaxed a bit. Or maybe I accidentally unbent them in the process of flanging. Anyway, I’ll double check them either before or after priming.

Final drilled all of the main ribs to the spars on both the left and right sides. Not sure if the leading edge ribs are supposed to be drilled at this time or not. I think they get left until later. The instructions sure do a lot less hand-holding compared to the empennage. Also deburred the holes in the spars.

Had some help on the drilling…

Squeezed the remaining rivets on the right rear spar. Riveted together the tie down assemblies and bolted them to the front spars. Didn’t bolt on the bellcrank brackets. As a few people have mentioned, it’s better to leave this until later. You can see from the picture that the spacers are not perfectly aligned. Shouldn’t matter a single bit.

Fluted the leading edge ribs (well, almost all of them). The leading edge ribs are much harder to flute than the main ribs. They have more of a curve, and thus require deeper flutes. My fluting jig also isn’t working as well for these ribs, causing it to take a bit more double checking with a straight edge and sighting down the rib.

I’ve kind of been working on both wings at the same time so far. I’m going to continue this until it becomes impractical. So far, it’s worked out great to figure out a task on the left wing, and then just repeat for the right wing. If I was working on them a few months apart, I’d have to re-learn everything for the right wing.

Still need to figure out the wiring runs. I’ll probably use the location suggested in the Orndorff video. I noticed somebody put two wiring runs in their wings, one for the antennas and one for the lights and strobes. That makes sense to me. I’m sure the antenna wires are pretty sensitive to noise. They are shielded, but it can’t be a good idea to run them right next to strobe wires for 10′. I also need to figure out what to do about the pitot. I’d like to have a heated pitot. Although I don’t plan on flying IFR a lot, I’d like to have the option. The pitot tubes at Spruce are $400+. I think I’ll probably use Dynon’s $200 pitot plus the Gretz $100 mounting kit. Even if I don’t use the Dynon AOA feature, their pitot is less expensive than the alternatives.

Big progress tonight. I riveted together the left rear spar. Only put one rivet where it shouldn’t go. It’s hard to tape over holes that you want to cleco.

I started riveting together the right rear spar, but then it occurred to me that I could cleco together the main left wing structure. I’ve been waiting all week for that. This sure seems like a huge step. I know there’s lots more to go, but this is the first time that I’ve seen the scale of this thing in the garage.