Matt's RV-7 Project

I used the hole finder to drill the last two holes in each side of the canopy skirt – they're the two silver clecoes in the middle of this photo. Also notice how the fiberglass skirt here on the right side of the airplane is slightly too long to match up to the edge of the C-660 side skirt.

On the left side, the skirt is slightly too short. Something must have gotten misaligned pretty early on. But it's no matter – I just cut a slight (1/8") taper on the rear corner of the left side skirt, and sanded the fiberglass skirt to match. Then I cut the same taper on the right side skirt and trimmed and sanded the fiberglass to match over there too. (Heaven forbid I shoud have an asymmetrical canopy!) It looks nice now, even though I seem to have forgotten to take a picture.

On the left side skirt, I trimmed an inch off the upper rear corner, where the bottom-most rivet hole in the plexiglass had way not enough edge distance on the aluminum skirt. This will all be covered with the fiberglass skirt once it's all put together.

Once the bottom edge of the aft skirt was finalized, I sanded a nice round profile on the protruding front corners, using a quarter to gauge the radius. (I used a Kentucky state quarter, but I think you could use any of the southern states with good results.)

Overnight I figured out how to fix the misalignment of the canopy skirt mounting holes. The nice thing about fiberglass is that you can usually fix your mistakes with enough patience and sandng.

I applied a layer of packing tape over the holes on the exterior surface of the skirt:

From the inside, I used a popsicle stick to force a thin epoxy/flox mixture into the holes. After I took this photo, I came back and squeegeed off the excess flox.

Once that was cured, I removed the tape and did the same thing from the exterior side, to fill both sides of each hole. When that was cured, I sanded it all flush. Here's the result – no more holes:

Then I put the skirt back on the plane, and after a great amount of measurement and double-checking I re-drilled the holes. This time it came out straight.

In some places, yesterday's holes were okay, but in others they were substantially off:

Since the alignment of the skirt to the plexiglass and frame was now acceptable, I went ahead and drilled most of the holes that attach the rear skirt to the C-660 side skirts. There are still a couple holes on either side that need to be drilled (where the obvious gap is in this photo) but I wanted to finalize the alignment before I removed the skirt again.

Without removing the skirt from the plane or otherwise disturbing the alignment, I drilled straight through the skirt, canopy, and steel frame with a 1/8" plexiglass drill, enlarging the holes in the skirt and frame to the final size (note copper clecoes in this photo). The holes in the canopy were already at 1/8", and will be enlarged to their final size of 3/16" soon.

Back on the worktable for more surface preparation and pinhole filling:

Yet more sanding… this time down to 400 grit.

I didn't like the blunt shape of the leading edge of the skirt up in the thickest part of the middle where the glass layers were doubled up, so I sanded it to get a gentler slope. Of course this means I'll have to do more pinhole filling here.

I re-drilled the skirt to the canopy using a hole finder, since the previous pilot holes got closed up by fiberglass filler. I think it must have slipped a little bit this time, though, since the alignment is ever so slightly skewed. It still fits and nobody but me will know it's crooked, but I may yet try to fix it. Not sure what I'll do about this yet.

I clecoed the C-653 cover strip in place and marked a line where the rear skirt overlapped it. Later I trimmed the cover strip so it ends just at the leading edge of the skirt. In retrospect, it would have been cool to mold the fiberglass skirt to fit over the cover strip perfectly, but I didn't think of it until it was too late. Oh well, a simple trim works just as well.

Also, my propeller governor arrived today. It's a PCU-5000 that I picked up for a good price through the VAF group buy that was organized a few months back.

I spent an hour sanding off the previous application of Superfil. Does this sound familiar? Anyway, this time I went all the way down to 220 grit paper – previously I'd been staying at 80 grit.

Now that the shape is basically how I want it, it's time to start preparing the surface by making it smooth and filling pinholes. For this job I'm using DuPont 210S, a single-part surface primer.

You're supposed to spray this stuff on, but it was too windy outside to spray effectively, and I didn't feel like getting out my spray gun and trying to mess with painting inside the garage. So, I just brushed the surface primer onto the skirt with a cheap foam brush. I'd never do that for a finish coat, of course, but for a filler coat it actually worked pretty well.

I put one one heavy coat, sanded with 400 grit, then applied two additional lighter coats without sanding in between. No rhyme or reason, I'm just winging it based on what seems reasonable as I go.

I kept the skirt up off the table with little balls of aluminum foil, to prevent the surface primer from getting all blobbed up along the bottom edge.

This is a picture of the third coat dying. The brush marks should sand right out.

It's starting to get smooth and look pretty good… is that the light at the end of the tunnel I see up ahead?

Here is what the skirt looked like after being popped off the airplane:

I marked a rough trim line, and then used a cutoff wheel to trim the excess glass to within 1/8" of the real shape of the skirt.

Then I block-sanded all the edges until the overhang was completely gone.

I sprayed another coat of grey primer…

…and sanded most of it back off again. Looking pretty good, only a few very minor low spots left.

I mixed up a big batch of Superfil and squeegeed a thin skim coat across the entire exterior surface of the skirt. Most of this will get sanded off, but what remains will fill the fiberglass weave and become the basis for future efforts to get a smooth surface.