Matt's RV-7 Project

I used a hole finder to drill the holes that will attach the fiberglass skirt to the canopy:

Then I spent some time laying out reference lines (perpendicular to the rivet line) at intervals of one inch along the entire skirt. These I used to measure and mark the true cut lines for the front and rear edges. Unfortunately I don't seem to have taken a photo of the skirt after all the trimming and sanding, but suffice to say it fits well and the edges are a lot nicer than this "before" shot.

My resupply order from ACS arrived, so I mixed up a big batch of epoxy and filler and applied it to the surface of the skirt, while it was being held in place with a single cleco on each side just to hold the shape.

I'll have to do a lot more filling (and sanding) before it's through – this is just a reconnaissance mission to fill the cloth weave and help identify low spots that need more filler.

I only had a few minutes to work on the airplane tonight, but I couldn't resist seeing how the most recent layup went. I removed the peel-ply, and there was the cured canopy skirt in all its glory. I traced the guide marks, which were dimly visible through the semi-translucent fiberglass, onto the top surface of the skirt.

It still pretty flexible around the longitudinal axis, but plenty stiff along its short dimension where it needs to be. I trimmed off the jagged edges and removed most of the tape residue from the fuselage and canopy, and here is the result:

The fit of the skirt to both the canopy and fuselage skin is excellent. I need to even out the dip in the middle with filler, but that at least is something I know how to do.

A 4-40 screw hole usually requires a #43 tap drill, but there's just enough material left in a regular #40 hole that you can tap it and get a screw to stay in. I used this fact to my advantage, tapping and running flush 4-40 screws into the holes in the aft canopy bow. I'm glad I waited to final-drill the rivet holes in the canopy frame, or otherwise I wouldn't be able to perform this little trick. These holes will eventually get drilled up to #30 for pop rivets, but for now the screws and tinnerman washers will hold the plexiglass in place without clecoes. I didn't do anything to secure the aft edge of the plexiglass last time, and I think it lifted away from the frame. This time, I can lay up fiberglass right over the top the screws, and the plexiglass will be perfectly held in its final position – the better to make a perfect set of aft skirts, I hope.

With the canopy latched and the plexiglass secured in its final position, I bridged the gap between the glass and fuselage with duct tape, then covered it with clear packing tape to keep the epoxy from sticking to the mold. Tightly-stretched duct tape seems able to keep its shape better and sag less than packing tape alone.

Cutting out pieces of 9-oz cloth:

I laid up four layers of fiberglass on each side of the skirt, with lots of overlap in the middle. This ought to be plenty strong. You can also sort of see that the shape is better this time.

I had a roll of peel-ply tape laying around, so I used strips from that instead of one big peel-ply sheet. No particular reason other than it happened to be handy.

And now we wait…

The canopy on a side-by-side RV is hard to open from the outside, no matter if it's a tip-up or a slider. I decided my canopy would benefit from having an exterior handle to help me open the canopy while standing on the ground, and I wanted it to be small, streamlined, corrosion-resistant, simple to install, and easy to replace. I found a nice looking stainless-steel cabinet handle at Home Depot that seems like it will fit the bill. For future reference in case I need to replace it, it is a standard 96mm size and is threaded for 8-32 screws.

I put some masking tape on the rear portion of the canopy frame to help me find the true centerline, and marked and drilled two holes into the center tube with appropriate spacing to fit the handle.

After deburring the holes in the top of the frame tube and enlarging the holes in the plexiglass, I drilled through the bottom part of the tube using a drill guide to keep the drill bit vertical.

With the plexiglass off the frame, I clecoed on the the C-653 cover strip and backdrilled the handle mounting holes.

I drilled the holes in the frame and cover strip to #19 for a #8 screw, and enlarged the holes in the canopy bubble to 1/4" to provide plenty of clearance between the plexiglass and the screw threads. I still need to obtain some screws long enough to go through the canopy tube, plexiglass, and cover strip – probably something like an AN525-832R20. Until then, here's a photo of the handle temporarily screwed to the plexiglass, just to show how the finished product will look:

Getting this little project out of the way means I can cross yet another item off my "things to do before the canopy can finally be riveted together" list. I guess you could say I'm starting to get a handle on the situation. Hah!

The plans tell you to attach the canopy directly to the forward bow of the frame with pop rivets, with no aluminum in between the fasteners and the plexiglass. This is the only place on the canopy where they show rivet heads bearing directly on the plexiglass, and it makes me worry to think about what will happen to those fastener holes when the glass starts to expand and contract with changing temperature. I decided I wanted to have the plexiglass securely sandwiched beneath an outer layer of aluminum everywhere it's fastened to the frame, in order to better spread the load and allow for thermal expansion. For lack of a better term I'll call this piece the forward canopy trim strip.

First I taped the canopy to the forward bow, so it would maintain the correct shape without clecoes:

Then I taped down a strip of posterboard so I could trace the outline of a template. (Side note: Notice how bright it is in these photos? That's what it's always like in my east-facing garage in the morning. It gets hot early, and the reflections from aluminum airplane parts are often intense.)

I cut out the paper template and taped it to a six-foot section of 0.032" I bought from Airparts last week.

After a few minutes of using snips, I had a rough and oversized blank cut out.

I clamped it to the canopy to test the fit…

…then drilled the rivet holes using the same technique I used to drill the ill-conceived metal aft skirts.

I scribed a line on the bottom of the aluminum hanging over the forward edge of plexiglass, then cut and filed the strip to just beyond the scribe line. That gave me an attractive front edge that was nice and flush with no metal sticking out to cut/pinch your fingers. Then once I had the front edge the way I wanted it, I marked the trimmed the aft edge to give the strip a uniform width across its entire length.

Right now I have the ends of the strip tucked underneath the canopy side skirts. There is a small ear on the lower end of the strip that picks up the forwardmost skirt-to-frame rivet (the lower silver cleco in this photo). I may also need to shim under the forwardmost screw hole (copper cleco) or otherwise put a bend in the front corner of the skirt to keep it from bowing out.

Here's the finished product, ready for final drilling and dimpling. When the canopy is closed, this will be hidden under the fairing that goes over the top of the rollbar, so you'll only be able to see it when the canopy is open.

Ahh, nothing like scratch-building something out of metal to get the airplane-building spirits back up.