Dave’s RV-7A Building Log

The weather did not hold out as was predicted. The rain prevented me from doing the last of the canopy painting. I didn’t have much time for the project anyway. Julie’s birthday is tomorrow, and I’ve been busy working on some things for her.

For plan B, I worked on the camloc strips some more. I’ve been debating about whether to scallop the camloc strips as I’ve seen other builders do. The weight savings is minimal. The only real benefit is that the camlocs can contour to the shape of the cowl better. Since the bottom strips need to be cut back anyway because of the honeycomb in the cowl, I did some experimenting. It was easy to do, so I’ll probably do the top strip as well.

I was reading some old posts on camlocs and ran across a good piece of advice. Since I’m keeping the hinges along the bottom part of the sides, I need to make sure I can get the hinge pin out. I’ll need to eliminate one camloc on each side. Had I known that in the first place, I wouldn’t have made the separate backing strips for the sides. Oh well. At least the spacing and positioning of the camlocs is still good.

May was a very productive month. Looking back over the past two years, I always seem to get a lot done in May. I guess the combination of decent weather and the Memorial Day weekend help boost the hours.

I did just a bit more sanding on the canopy to bring the upper edge of the fairing even with the single layer of electrical tape. I also sanded out a couple of spots that were rough. One more shot of primer and it’s good enough to fly.

I also sanded and prepped the cabin frame for one more shot of paint. It was just a little to bumpy after the last coat.

Today was the first unofficial function of the Eastside EAA 1440 chapter. A few of us flew down to Thun field. It had to be an unofficial function, since our chapter is not officially formed yet. Mike and Michael brought their Luscombes, which are really a pretty plane. And Ron was there with his Fly Baby, which looks like pure fun. Some day I’ll arrive in style in an RV rather than a 172.

I had a little time for the project. I re-drilled the left canopy lug and drilled both lugs out to #12 for AN3 bolts. Julie helped me remove the canopy from the plane, since that was the last thing I needed to do while it was installed. It was extemely difficult to get the struts off. There must be a trick to that. I have a few more little things to do on the canopy and then it will get stored until final assembly.

After dinner, Julie helped me finish the riveting on the back top skin. I could have reached some of the rivets from the outside, but it’s easier to just crawl inside. This skin has been in the process of being riveted for a long time (Christmas) mainly because it just wasn’t a big priority. It’s nice to have it done.

I crawled back inside again to attach the shoulder harness cable brackets. One more trip back there for the static tubing and that should be it for the rear fuselage.

I worked some more on the camloc backing strips. It’s really not obvious how to install these. I initially cut them too short. Luckily I had some extra material. I clamped the strips right where I wanted them and started drilling down from the middle.

I also drilled out the hinges I previously installed along the bottom and cut and drilled strips for that area. I’m going to keep the hinges on the sides.

Then it was time to enlarge the holes in the backing strips with a Unibit. This step makes a huge mess.

I countersunk the bottom strips, clecoed them in place and enlarged the holes in the cowl. I installed the collars and camlocs into the cowl and then test fit it. Looks good.

Long day, but very productive.

Did more countersinking and installed more nut plates. I also riveted the back plates to the spinner after checking the clearance one more time. The spinner is now complete and looks excellent.

Now for the moment of truth. I’ve had the spinner on for a while but have been afraid to install the cowl. I fitted the cowl without installing the prop or spinner, so it was a bit of a guessing game. Well, it turned out much better than I expected–maybe even perfect.

Even the gap looks really good.

This thing is really starting to look like a plane.

From there I started working on installing the camlocs, primarily on cutting the backing strip.

Countersunk the spinner and started installing nut plates.

Lots of drilling and deburring. I riveted the nut plates to the tabs and the tabs to the filler plates. I just need to rivet these to the spinner back plate.

I then drilled all of the holes in the back plate out to #19 for #8 screws. I was in the middle of using the nut plate jig on the back plate when I realized I made a mistake. Instead of drilling for 14 screws around the whole spinner, I drilled for 14 on each side. I guess I just zoned out when I was measuring out the holes. I knew things were going too smoothly. Frustrated is a huge understatement for my mood. I don’t want to re-fabricate that stupid back plate and remove & re-install the prop. I’ll call up Vans and see what they say about it. I know it looks obvious in the picture, but it wasn’t so obvious before I drilled for the nut plates.

I took a break for a while and thought through the issue. I was thinking of just leaving out every other screw, but that wouldn’t work. I’d end up with a big gap at one end or the other. The only fix is to re-drill, which means a new back plate.
[5/26/2006: Miles at Vans confirmed the extra screws aren’t a problem. I’ll just have a very unique (and secure) spinner.]

I moved on to something else. I drilled the holes for the front plate. That went pretty smoothly. I laid out the holes on the plate, drilled them, and then using a flashlight drilled through the spinner into those holes. Worked well.

I worked on the spinner filler plates some more until the prop had 1/8″ clearance at coarse pitch. I made two small pieces of Al sheet to hold the filler plates in place per the plans, although I used .032 instead of .064. The thinner sheet is plenty sturdy enough.

I sanded the inside of the spinner a bit more where the front plate hits. The spinner is not absolutely perfect but it’s within 1/32″ of where I want it to be. I don’t want to reduce the structural integrity of the spinner by sanding it too much.

I carefully measured and marked the pattern for the screws and rivets on both the spinner and filler plates and drilled all the holes to #40 to start.

With everything clecos in place, I checked the coarse pitch one more time. I’m glad I did. There were a couple spots that were still a bit tight. Once I rivet on the filler plates, it’ll be much harder to tweak the gap.

I tweaked the cutouts in the spinner a bit more with some sand paper and got them right where I want them. I then turned to the plates that go behind the prop to fill in the gap. The fiberglass I cut out will work nicely. I cut them down to size with the die grinder and belt sander. I didn’t think twisting the prop would affect them, but it does. Julie helped me mark how much to remove. Just a tad bit more sanding.

I used the plexiglass disc in the die grinder and made the cutout in the spinner. I finished it up on the belt sander. The end of the belt sander worked perfectly for cleaning up the curve of the cutout. From there it was several iterations of enlarging the cutout with a half-round file and sand paper in order to give the prop 1/8″ clearance all the way around. I used the strap wrench to rotate the prop to high pitch to check that clearance. It ended up being a bit more than I wanted, but it’ll be fine.

I found that the spinner wouldn’t go far enough back, because of the front plate. I sanded the inside of the spinner a bit and got it fitting pretty well.

The instructions mention it’s important to make sure the spinner is concentric with the engine shaft. It says to identify a point at the tip of the spinner and make sure it’s stationary as the prop is turned. However, since the engine is preserved, I shouldn’t spin the prop. Instead I measured from the point at the tip to back edge at several locations. It’s pretty close, but one side is a tiny bit longer. I’ll do some sanding to correct that and straighten the back edge as well.