It’s December 29 and I’m finally getting a chance to complete this post on finishing the rear window. So for all you Mighty RV fans out there (I think we’re now up to three), here’s a narrative on trimming, fitting, marking and drilling the final part of the canopy.

Vans’ instructions call for rough-marking the rear canopy trim line before cutting the canopy into forward and rear sections. For some reason I didn’t do that, so with the forward canopy separated and placed in approximately the right position, I laid the rear canopy over the fuse and marked a “do not cut” line around the fuselage skin edge.  Yeah, I went over the top with reminders about where not to cut…

I then did a rough estimate of a “cut here” line based on the no-cut line. I don’t recall the distance, but it was generous – I took off just enough so that the canopy would fit under the skin.

Here’s the first cut line marked with masking tape. I like that Scotch yellow-green masking tape…it just looks more “aerospace-y.”

I got the first trim cut just about right; the rear canopy seats nicely around the skin edge, and there’s enough overlap of the roll-bar to make it easy to final-trim the forward cut line that abuts the front canopy.

The only thing you can’t see in the above picture are the bits I had to cut out of the forward lower corners of the rear canopy so they’d fit around the roll-bar attach fittings.

One final task before drilling to the skin and rollbar – marking hole locations for the screws that attach the fuse skins to the canopy. I borrowed a trick from Mike Bullock and used a piece of masking tape to lay out hole spacing. I laid a piece tape parallel to the skin edge at the correct edge distance and marked the location of the first and last screw holes.

Read the plans carefully here, because Vans doesn’t explicitly call out the edge distance – it’s inferred from one of the cross-sections depicted in the plans.

With the first and last hole marked, I pulled the tape off, measured the distance between the first and last holes, and did a little airplane builder math to mark the rest of the screw hole locations. After that it was an easy matter to put the tape back on the fuse and mark the holes for drilling.

One side note – regular masking tape is kinda stretchy for laying out hole spacing, so I used some 3M plastic fine-line auto painters tape I had laying around from a previous project.  This stuff worked great – it was easy to get the holes spaced perfectly because the plastic tape didn’t stretch much at all.

Laying out screw holes on the roll bar was easy – all I had to do was match the locations of the holes I’d already drilled for the front canopy.

I bribed Ellen with the promise of a nice dinner at our favorite Mexican restaurant if she’d come up to the hangar and help drill the rear canopy, which she graciously agreed to do.

This was a piece of cake compared to the front canopy but there are a couple of tips that help improve the drilling process. First, it’s a good idea to pre-drill the fuselage skin holes with a small drill bit without the rear canopy in place; the small holes help center the tip of the 1/8″ plexiglass drill bit when match-drilling through the canopy.

And second, be careful to not drill through the rollbar with the plexi bit – this would enlarge the holes past the size necessary for a #6 tap. Use the pre-drilled holes on the rollbar to locate the holes, then drill  them with the plexi bit just deep enough to break through the opposite side of the canopy, then enlarge later to full size when the canopy is off the frame.

And here’s the final product after match-drilling. I still have to trim the forward edge to match the “big cut” line, polish the canopy edges, countersink the screw holes and drill them to final size, but everything looks good for now.

I won’t trim the forward edge until I get the front canopy back on the frame with the lift struts installed S.me builders say that the struts push the whole frame aft, so I don’t want to do any edge trimming until the canopy is sitting in it’s worst-case position with respect to the gap between halves.

P.S. – If I haven’t mentioned it recently, I think I’m one of the luckiest builders – and really, one of the luckiest men – I know to have a wife and partner like Ellen. She’s learned to be an ace riveter, encouraged me to keep going when I’ve wanted to quit, and helped me keep perspective on the truly important stuff – and I don’t mean the airplane.

Thanks, sweetie…

I’ve been busy over the last couple of weeks on consulting projects so I haven’t had the time to work on the airplane until this weekend. On Friday I finished adjusting the forward canopy skin to accommodate the canopy itself.

Look at the little piece of green duct tape in the lower left corner of the picture above…that arrow-shaped opening is the final result of trimming the “fingers” in the skin so that the canopy sides transition smoothly to the side rails.

I spent the better part of the day laying out and pre-drilling holes that will eventually accommodate #6 screws that attach the canopy to the frame. After that Ellen and I put the canopy back on the frame, then taped and clamped it in place for drilling.

Here’s a pic for the Friendly Aviation Administration to show once again that yes, I’m actually building this thing…

Starting at the top of the canopy bow, we drilled #30 holes through the plexiglass into the frame using an Avery plexiglass bit.  We anchored the canopy down on one side and then the other by drilling and clecoing holes 6″-8″ apart, then went back and drilled the rest of the holes.

This is a Big Deal…there are only a few minor adjustments left on the side skins, and I still need to trim the rear of the canopy to it’s final cut line, but those are small tasks that I can finish in a day.

Cutting the canopy isn’t something to rush. I read and re-read Vans’ instructions, and researched other builders’ websites, to get a good idea of how to trim the canopy without damaging it. A replacement canopy is more than $1000, so cracks are something to be avoided.

I started this part of the project a few weeks later than I wanted to…my hope was to get the canopy cut and installed in August while the temperatures are still warm enough to not keep the hangar heat turned up. Fortunately, September has been fairly warm so not too much hangar heating has been required.

I set up everything needed to start trimming.  Per the instructions, I first cut off the portions the canopy where it was clamped in place for molding.  The back of the canopy was the first to go…

…and trimming turned out to be a little easier than I thought, but some care is required to get close to the cut line marked by the tape.

The cutoff wheel creates a lot of plexiglass “snow” particles as it works, except that this snow can be uncomfortably hot when it hits your skin. I didn’t want any of that crap in my eyes or up my nose, so I wore safety glasses and a respirator…

I continued the process around the sides and front.  It was a little difficult to tell where the cut lines should be, especially on the sides.

With the clamp marks trimmed off, I marked a centerline on the canopy per Vans’ instructions. This is a little tough to do as it’s hard to accurately place a tape measure around the canopy.  I wound up using a piece of string pulled tight from side to side…mark  the string where it lies on the edges, then double it back on itself and you have the centerline – sort of. I don’t think it was very precise, but it also seems to be close enough.

There are a couple of tabs on the front canopy frame that overlap the side rails. The instructions require that the tabs and side rails be adjusted to match the curve of the canopy’s front edge, then drilled and riveted. There’s not a lot of guidance here, and it’s hard to see through the protective plastic sheeting on the canopy to tell how the curve should lie. So…I took my best shot.

And then riveted the tabs…

…and everything looks good for now.

I’m reasonably happy with the canopy fit, so I started marking the line across the rollbar where the canopy will be cut into forward and rear sections. This process is not-really-affectionately known to builders as making The Big Cut.

I worked on the front edges a bit to get them to lay down a little more accurately on the front canopy skin, but from what I’ve seen on other builders’ websites, you can do all the work on this area you want but once the canopy is drilled in place, some gaps will open up.  So I’m going to get it close and not worry about it.

I hoisted the canopy onto the sawhorses and plywood, and used some long 2x4s to move it off the work surface They also gave me something to clamp some smaller pieces of 2x4s as side supports that keep the canopy from spreading as I cut it.

As other builders have also done, I laid several pieces of masking tape along each side of the cut line to help guide the cutoff wheel. I was skeptical that this would work, but it did and very well too.

I took a few deep breaths, and started cutting…

…and the process went very well. I used tongue depressors to keep the canopy separated  as I worked my way along the cut line.

And here’s the completed cut…what a relief to have this done.

It’s a lot easier to move the canopy on and off the fuselage. I’ll be doing a lot of that as I finish fitting it to the frame and then drilling the attach holes.

Got just enough time in the hangar tonight to rivet the canopy frame together and put it back on the fuselage. I left the primer to dry for a couple of days, and the Nason etching primer I used was tough as nails!

There’s an small and easily fixable mistake in this pic. Can you spot it?

And now it’s time to start trimming the canopy…yikes!

More fun with the canopy this week as I spent several hours adjusting the fit of these parts that form the rear canopy frame.

The distortion caused by both the flanges and L-shaped bend in each frame half takes some work to make them fit adequately. The instructions tell builders to flute these parts to remove the distortion, but at least one of mine was just about right out of the box and really didn’t need fluting. The other one doesn’t fit quite as well, but I’m resisting the urge to flute it because (a) the fit isn’t that bad and (b) I tried fluting a spare frame part I had and it was a PITA.

In this picture the frame halves are not perfect, but they’re getting close to being good enough.

The side rails were an easier fit, because Van’s had already done all the bending and metal shrinking needed to make the side rail curve fit the longeron bends I worked so hard to perfect several years ago.

The side rail flanges don’t quite conform to the aft frame parts, but I think they’ll pull into shape pretty well when they’re drilled and clecoed.

I still have some parts to fit to the frame, so stand by for more words and pictures.

Laying out the side rail and rear canopy bow splice plates. Note that the side rail doublers at the bottom have one hole that isn’t marked to be drilled – that’s because Van’s conveniently forgot to mention in their plans that there’s already a hole through the canopy frame in this area, and if you drill the hole in the splice plate it won’t line up with the frame hole.

Ok, so I said I wasn’t going to flute the rear frame – but I did, and it actually came out pretty well. Here’s the side rails and rear frame clamped into position.

The little cheapo Harbor Freight clamps are holding on some strips of 0.032″ scrap that simulate the canopy side skins. The side rail is correctly placed when the bits of scrap lie flush with the side of the fuselage.

Sharp-eyed RV builders will see that I’ve inserted a shim between the side rail welded angle and the F-631 rear frame half.  The fit wasn’t quite what I wanted, so when in doubt – shim it out. After that I couldn’t think of a good reason not to drill everything, so I did.

These plates splice the side rails to the forward canopy frame, and drilling them was a bit of a pain. It’s vital to uncleco and peel back the forward canopy skin, as nine of the ten holes in this part don’t go through that skin and drilling through it would be uncool.  You’ll see one hole (bottom row, second from the right) that doesn’t quite line up. That hole *does* go through the skin and frame, and once the other holes were done I back-drilled this one using the forward frame as a guide.

And here’s everything drilled and clamped to make an almost-complete canopy frame. As my friend Jim would say, this is one of those moments of Big Visual Progress. They kinda sneak up on you after a lot of tedious fitting and drilling, then suddenly everything comes together…et voilà, it looks like a real airplane part.

I hated to take everything apart, but there are a couple of small parts left to fabricate and fit to the frame.

Look carefully in the pic above, just under the two leftmost copper clecoes, and you’ll see a thin aluminum wedge filling the gap between the side rail splice plate and forward canopy frame flange. Scroll back a couple of pictures and you’ll see the unfilled gap.

I had to make two of those – one on each side of the canopy – and each one took about an hour of cutting, sanding, filing and fitting.  What fun…but now I can take the frame apart  and debur, countersink and prime everything before riveting. And that, in turn, means it’ll soon be time to work on the plexiglass canopy itself.

After drilling the canopy hinges, I had to do some filing on the seal support angles so that the canopy would open without rubbing on them. Not really much to see, because the seal support angles are hidden in this pic.  But the canopy frame now pivots the way it should, and that’s worthy of a picture.

A solid week of airplane building…missing Oshkosh, but getting a lot of work done.

I’ll be adding text here when I get the chance.  Right now it’s a holding place for pictures so I can document what I got done…more to follow.

Matco PVPV-D parking brake and doubler –

Doubler plate taped to firewall

Testing out my plumbing idea.

Parking brake taped into place to check lines

Parking brake valve crossover lines installed.

Brake lines protected against abrasion with spiral wrap. Somehow it makes them look more “finished.”

Canopy latch parts painted

Massaged the canopy frame, then reinstalled skin. Flush dies in the pneumatic rivet squeezer helped work out inadvertent creases in the skin, and a flush set in the rivet gun helped with the frame.

Canopy taped in place with spacers installed for final fame drilling.

Riveting the canopy frame. It’s about time I put that 12″ double-offset back rivet set to good use.  It sucks up a lot of kinetic energy, though…90 PSI on the compressor just to get the rivets to set.

Another picture of riveting the canopy frame

Here’s the canopy frame riveted, with the skin reinstalled, and fitted back into place on the fuselage.

Final fit before drilling the hinge brackets

Fit is pretty good on the right side.

Canopy hinges drilled and bushings installed