Matt's RV-7 Project

I started the day by riveting the C-791 skirt braces to the side skirts. I also applied a strip of UHMW tape along the bottom edges, to keep the skirts from scuffing the paint on the fuselage.

I also put some UHMW tape at the trailing edge of the aft skirt, for the same purpose.

The first part of the canopy to get permanently riveted to the frame was the little lock bracket, which I attached with a couple of LP4-3 blind rivets.

Then I clecoed the whole canopy together, inserting screws along the sides, and checked the fit one last time. Finding everything to be satisfactory, I used more LP4-3 rivets to attach the tops of the skirt braces to the inside of the canopy frame.

Here's a little trick I picked up from somebody's website: by drilling the fastener holes 1/16" oversize and making tiny little bushings out of 1/32"-wall surgical silicone tubing, you can keep the fasteners from ever contacting the insides of the holes. Theoretically this should help prevent cracking, but it ought to also have the side benefits of preventing rattles and making the canopy more watertight. Anyway, it wasn't a big deal to make these little bushings, and I'm all for anything that will help keep my canopy in one piece.

With everything clecoed in place, I applied electrical tape to the plexiglass along the edges of all the various skirts and cover strips, and followed up with blue masking tape to cover any remaining exposed plexiglass. I prefer this combination when I need to very precisely mask around objects with irregular contours, and just about everything on the canopy is curved in some way.

Here's where the construction photos stop, because for the rest of the afternoon I had sticky fingers, the clock was ticking down the working time of some glue, and Mary wasn't home to help with camera duties. So, here's a textual description of the next four hours' worth of work:

The weather outside was unseasonably cool today, so I had to keep the garage door closed so the temperature would stay up in the 80's and make the plexiglass happy. Because of the solvents and glue I was using, I had my VOC respirator on the whole time to keep from gassing myself.

I began by removing the aft skirt and the center and forward cover strips and putting down a bead of Lexel on the exposed plexiglass. The side skirts were non-removable at this point, but I was able to remove all the clecoes and force Lexel down into the gap between the side skirts and canopy. If you're interested, a toothpaste-tube-sized container turns out to be enough to do one canopy.

I made a special effort to goop a bunch of Lexel into the cavities formed by the 7/16" holes in the plexiglass where the stacks of washers go to support the exterior handle. It wouldn't do to have water leak in along that path. Some masking tape on the interior side formed a temporary dam to keep the sealant from dripping down into the fuselage.

After all the sealant was dispensed, I tightened the nuts on the #6 screws that attach the plexiglass to the side skirts, and then put the aft skirt and cover strips back on and clecoed the canopy back together.

After tightening the screws and reinstalling the clecoes, there was a tremendous amount of sealant squeeze-out to deal with. I cleaned up the biggest blobs with popsicle sticks, and then removed the masking tape, but there was still a bunch of sealant oozing out from under the exterior pieces. The surfaces of the skirts and cover strips were also heavily contaminated with Lexel. I dealt with this by removing one cleco at a time, cleaning the affected area with naphtha, and replacing the cleco. Naphtha was the only thing I'd found that would remove Lexel without damaging plexiglass, and I bet I used a half-gallon of the stuff. Plus a bunch of shop rags and elbow grease.

Then I started replacing clecoes with rivets, using the cool pneumatic puller I bought at Oshkosh to pull the blind rivets. This tool was totally worth the investment, as it almost completely eliminates the risk of gouging the surface of the part with the broken-off mandrel that you get when you pull pop rivets with a hand tool. To me it was a no-brainer to buy this tool in order to protect my canopy from damage. Plus it was on sale.

Installing the rivets caused more Lexel to squeeze out, so I revisited each area with naphtha as I pulled the rivets. Ideally I'd like the sealant to be minimally visible – the canopy will still be watertight if the sealant is out of sight underneath the skirts, and it will look better that way.

I kept repeating the last two steps until I ran out of holes, and then suddenly the canopy was done. I pulled off the remaining protective plastic, and there it was in all its glory:

Same view from the other side:

The aft skirt (held in place with tinnermans under the rivet heads as planned) fits as perfectly as can be:

There is very little resistance in the rollers – the canopy can be opened and closed with one finger.

The exterior handle looks like it was made to go on an airplane:

The only perceptible gap between the side skirts and the fuselage is towards the very back, just in front of the fiberglass aft skirt. This is a pretty typical place for an RV to have a gap, and mine is a lot smaller than most other airplanes I've seen. Later on, I will seal this by riveting pieces of angle inside the fuselage to close up the gap.

Mary eventually came home and took the requisite triumphant photo of me enjoying the view from inside my newly completed canopy:

All in all, I'm extremely pleased with how the canopy turned out. There are a couple more little details to finish up, but the hard part is over. This has been, without a doubt, the most difficult and frustrating phase of the project to date, but I have emerged victorious. And now, for the celebratory libations!

This entry was posted on Sunday, September 9th, 2007 at 7:50 PM and is filed under Canopy.