Almost finished with the cowl

We don’t plan on painting the RV for awhile, so I called Jonathan McCormick at Evoke Aviation – our painter of choice – and asked for his recommendation about how to protect the cowl ’til time for paint. His recommendation was K36 high-build epoxy primer…so that’s what we used.

The K36'd cowl

The oil filler door looks good, although I’ll likely end up sanding down the sides a little to increase the gap for painting later on.

The oil filler doorAnd the cowl pin covers look great…couldn’t be happier with how they came out. They were worth all the work!

The jeweled cowl pinI disassembled the cowl and laid down some heat-reflective adhesive aluminum to help protect against hot spots from the engine.  Sorry, no pictures of that!

Sanding, sanding and more sanding

Following the instructions for UV SmoothPrime, I’ve laid down several coats and each one means a lot of sanding. Fortunately, it sands pretty easily and seems to do a good job filling any voids or pinholes left after the coats of micro and epoxy I applied.

The cowl after SmoothPrime

It’s a little splotchy in some spots, but it’s good enough for the high-build epoxy that’ll cover everything until paint.

SmoothPrime splotches

Bits and pieces, and the end of the pink cowl

There are a lot of gaps in the blog since February because any spare time I have has gone to building and not to blogging. So in the spirit of documenting this build in an efficient manner, I’m gonna “micro-blog” and just cover a single day’s work…so there.

The pink cowl is no more. I put on the first three coats of UV Smooth Prime with a roller and after drying for a day or so I’ll sand it down and put on the final coats.

The pink cowl…

The last of the pink cowlAnd the the white cowl…

The white cowl

 

The final stretch and shrink

With the plexiglass canopy parts mostly under control, I’ve moved back to finishing the canopy frame and skins.

Final-drilling the rear canopy frame

First off, I finished match-drilling the rear canopy frame. Nothing too difficult here.

Rear canopy frame riveted together

I pulled the frame off the fuselage then deburred, countersunk, primed and riveted everything together. Then, I started on the canopy lift strut attach brackets.

Tapping the forward strut attach points

The forward attach points require a lot of tweaking and fitting to fit inside the forward canopy frame. Once match-drilled, they’re tapped to accommodate #10 screws that keep them in place on the frame, and also for the large “knob” that provides an attachment point for the lift struts.

Quality Chinese taps

This quality Vermont American tap failed on its second use. I did a little research on where VA’s tools are made, and it seems like their name should really be Vermont Chinese, or Guangdong German, or something that more accurately depicts where the company really resides.

Not that I mind buying cheap Chinese shit tools…I go straight to Harbor Freight when I need a tool that I’m gonna intentionally tear up or modify, only has to last for a few uses, or most importantly, is something that my life won’t depend on.

Rich's lift strut attach points

I’ve been waiting a long time to use these custom-machined canopy strut mounts from Rich Mileika at Machine, Inc. Not only did they save a lot of fabricating time, they look really cool too.

Locating the right position for these mounts was the easy part; getting them screwed into place was harder.  Once the mounts were match-drilled to the canopy rails for #10 screws, I had to get up, under and behind the canopy rails to get the locknuts in place.

Lift struts installed

I didn’t have any wrenches that would get into this spot, so I improvised…I took a cheap 11/32″ socket, hammered it onto a piece of 1/4″ aluminum fuel tubing, and bent the tube such that I could get the socket around the canopy rail. As ugly as it is, it worked like a champ. After I used it to get the mounts installed, I pulled the socket off and reattached it with JB Weld – probably won’t be the last time I’ll need to use this device.

Struts mounted

Here’s the canopy frame with the lift struts attached. Cool.

Canopy with lift struts

I put the canopy back on the frame…it’s time to start fitting the side skirts.

Canopy ready for skirt installation

The challenge here is getting the skirts clamped in place. Some builders have made some really spiffy clamps out of aluminum C-channel to slip under the skins and hold them in place, but I didn’t have the patience to do that.

Double-sided tape for skirts

Instead, I just used some 3M two-sided tape to hold the skirts in the correct position until I could raise the canopy and clamp them with regular Pony clamps.  In the pic above you can see that I’ve already laid out and pre-drilled the side skirt rivet holes.

Skirts taped in place

Lookin’ good prior to drilling…

Skirts drilled to canopy

And after several minutes sitting inside the closed canopy (cool!) with an air drill, the side skirts were match-drilled to the frame. Not much left at this point except to countersink the frame holes and debur/dimple the skirts.

One of the things I wasn’t too happy about was the fit of the forward canopy skin to the forward fuselage skin – they just didn’t quite line up.

Metal shrinker in use

As I tend to do, I threw money at the problem. I made a trip to Harbor Freight and bought a metal shrinking/stretching tool set. After practicing on some scrap sheet metal, I used the metal shrinker on the leading edge of the canopy skin.

Forward canopy skin fitted

The results were better than I expected…the metal shrinker really closed up some of the gaps between the canopy skin and forward fuse. Unfortunately, I didn’t get a picture of the fit with the canopy installed, so you’ll just have to trust me.

One slight downside to the metal shrinker is that it leaves small toothmarks on the metal when it’s used – but a scotchbrite pad on the die grinder made quick work of them.

Canopy brace

Like most tip-up builders, I chose to install the optional canopy reinforcement kit. Otherwise the canopy frame is pretty floppy even when the canopy bubble is installed. There are a lot of holes and slots that need deburring, fortunately there really isn’t much more of this to do on the project.

The plans call for the three large lightening holes to be “flanged”, or have the edges of the holes bent slightly to make the metal stiffer. There are lots of way to do this, and I chose the old-fashioned way – a piece of delrin with a slot cut into it, which is used to bend the edge as it’s slid around the inside of the hole.

More flanges bent

It’s a pain, because several passes are required to get a good bend – but in the end, the flanges came out great.

Canopy stiffeners match-drilled

Here are the stiffeners drilled to the canopy frame.

Clips partially drilled to canopy frame

There are small tabs to be fitted and drilled to the stiffeners…not hard to do.

Both holes drilled in clips

…and they’re done.

frame ready for deburring and priming

At long last, it’s time to prime the canopy skins and stiffeners, and rivet them to the frame.

Primed canopy frame parts

Blecch…priming. I’m glad there isn’t much more to do.

Primed canopy frame

Priming the canopy frame was a pain, but hanging it from the engine stand made things easier.

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The canopy skin doesn’t fit particularly well on the frame, so I used an epoxy and flox mixture to fill gaps between the skin and frame. Once it cured, Bob DiMeo and I riveted the skins on. The epoxy/flox mixture worked pretty well – there aren’t the dimples in the canopy skin that I’ve seen on other projects.

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More riveting fun, this time after several pop rivets have been pulled. The pop riveter takes some manual effort to use, and my forearms are aching.

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Unfortunately I neglected to take any pictures while I painted the canopy frame interior with   JetFlex WR. This took a long time…I did a lot of repainting to get a good finish, and it was a real pain.

After the JetFlex dried, I masked off the glareshield for surface prep, priming and painting.

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I used a good flat black automotive enamel to paint the glareshied, and it came out very nicely.

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I installed the canopy strut pivots…kinda satisfying to do something so simple.

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Here’s a bit of visual progress…the painted canopy frame with the canopy installed. Very cool!

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Another picture? Sure, why not…

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The last bit of work was installing the aft canopy latches.

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I don’t have much to add to the instructions, except that I had to do some improvising to keep the latch fingers clamped in place while I match-drilled them. A piece of spruce filled the bill.

I also clamped and drilled the upper canopy safety latch block to the canopy frame. Unfortunately, I forgot to take any pictures so you’ll have to use your imagination. I deviated from the plans a little and installed a spring beneath the washer and cotter pin that hold the handle in place. Once the block wears a bit and the handle turns more freely, the spring will pull the handle tight against the frame and keep it from inadvertently rotating to the close position, with the unfortunate effect of locking the canopy from the inside. It’s happened to other builders, and I’d like to avoid all the gyrations they had to endure to get the handle unlatched.

Installing the canopy release pivot

Most tip-up builders don’t go to the trouble of installing the canopy emergency release because (a) no one has ever bailed out of an RV-7, and (b) the release handle takes up valuable real estate on the instrument panel.

I’ve been debating the merits of installing the release for a few years, and finally came to the conclusion that I’d rather have it and not need it rather than the other way around. I also want to keep the instrument panel relatively simple, and keeping space for the release handle forced me to do that.

The first step was to drill the release pivot block to the hat section on the subpanel.

Cutting the hat

With the holes drilled, I installed nutplates to accommodate the attach bolts.

Canopy latch temp fitted

In this picture the pivot block and actuator arm are in place and attached to the canopy hinge pins with steel rods. Actually, the left rod isn’t connected to the actuator because the rod was slightly short even though it was fabricated according to the plans. So…I got to fabricate another one that was 1/16″ shorter.

There’s not much to add about fabricating the steel parts, except that the slots in each steel rod that accommodate the actuator and pins are most easily cut with a Dremel tool with a cutoff wheel. Some work with files will still be required, but the Dremel will get 95 percent of the cutting done.

The release mechanism is on the shelf now, and will be reinstalled right before I’m ready to rivet the front fuselage skin in place.

 

Rear Window

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…

Rear window marked for cutting

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.

Rear window cut line taped

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

Rear window trimmed and temp fitted

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.

Rear cabin skin screw line layout

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.

Rear window screw locations laid out

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.

Rear window drilled 1

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.

Rear window drilled 2

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…

Drilling the canopy

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.

Frame drilled for canopy

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.

Canopy skin finger trimming

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.

FAA proof photo 1

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

FAA proof photo 2

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.

Canopy drilled to frame

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.