Breathing is Good!

Installing Oxygen Cylinder Brackets

Call me old fashioned, but when it comes to operating an aircraft, I have always maintained that it is important to remain conscious. A key requirement for most carbon-based lifeforms that respire is oxygen. Most people take it for granted but if you fly in a non-pressurized airplane, it’s something that requires special thought. Furthermore, if you’re building such a plane you need to decide whether to furnish oxygen for you and your passengers or go all ‘BYOO’.

For some aircraft, especially those that fly “low and slow”, supplemental oxygen may not be a top concern. It wasn’t something I thought much about when I owned my Maule–until it was. During a long cross-country flight, returning to the Seattle area from the Midwest, I needed to climb to around 12,000 feet to clear a broken cloud layer that was “just chillin'” up against the west side of the Cascades. By regulation, I didn’t “need” supplemental oxygen (though I would have if flying under part 121 or 135), but it was high enough to feel the effects. As I was contemplating the intricacies of FAA oxygen regulations, I also found myself noticing how pretty the puffy clouds were and how everything was just so lovely and…in other words, the first signs of hypoxia.

Clouds and pointy rocks–what could be better?

When planning my RV-10 build I considered whether to install a built-in oxygen system, as some builders have, or to rely on a portable solution whenever I planned to fly at high altitude. My initial decision was to opt for the latter, partly due to being unsure how often I would really need oxygen and partly because of the cost of a permanent system. Things began to change, though, as I got further into the build. First, after pulling the trigger for pricy upgrades like after-market rudder pedals and fuel and brake systems, I became less resistant to spending large sums of money. I also thought more about the prospects of cross-country travel from our current home base in the Denver area. Facing east, the landscape appears as a flat table top for as far as the eye can see. Turn around and it’s a different story. It’s impossible to avoid the big pointy rocks if you want to head west and safe margin of error above terrain puts you squarely in the “oxygen required or highly recommended” zone. In the end, it was my wife who pushed me over the edge, reasoning (correctly) that, not only would oxygen come in handy, but a built-in system made sense for the trim level I was building towards. So, as always, when the spouse gives the go ahead to spend money, I didn’t let the moment pass.

Extensive Research?

The process of building a sophisticated airplane is a funny thing. Some decisions you obsess over, compiling graduate student levels of research materials. Others you make quickly, even if there are cost and complexity implications. When it came to the oxygen system I went with the latter and chose one from Mountain High Equipment and Supply Company. The company has been around for almost 40 years and sells all types of built-in and portable oxygen systems aimed at the Experimental/Amateur-Built market. I went with their top-of-the-line EDS-4ip system, which is a “pulse demand” system that includes all the components for a permanent install in a 4-place aircraft like the RV-10. According to the, a pulse demand system (as opposed to constant flow, like you find in hospitals) is the more efficient because it dispenses oxygen only when it detects a user’s inhalation, leading to dramatically higher durations of a given supply. Plus, as a builder who likes to build, it comes with lots of stuff to install!

New kit always makes me happy.

I’m sure an exhaustive search would have turned up additional options, but I decided to go with this setup primarily because other builders have done the same and I knew I could learn from their experience installing and using the system. Also, Mountain High makes it easy for builders like me who are working through the build at a more relaxed pace. They sell the system in three “kits” that let you spread out the cost and work:

  1. Plumbing Install – The cylinder mounting brackets plus the distributor outlets, electronic connectors and all the tubing
  2. Control Head – The “brains” of the system that gets mounted in the instrument panel
  3. “Fly Away” – Oxygen cylinder and regulator, cannulas and mask

After a quick call to Eric at Mountain High, the Plumbing Install kit was on its way to GAF (Gilbert Aircraft Factory, a.k.a., my garage).

Planning the Cylinder Bracket Install

After unpacking the kit and expressing the requisite “Ooh!”, “Ahh!”, and “Cool!”, I set about planning the cylinder bracket install. However, without a cylinder as a reference, I was unsure exactly how much space it would take up. Fortunately, Rodrigo Damazio Bovendorp clued me in to Mountain High’s loaner program. For a small deposit they will ship you a decommissioned cylinder to use during the installation. I didn’t know about this when I placed the original order, and so had to wait a few more days for it to arrive, but I’m glad I had one in hand as it made visualizing the outcome I wanted a lot easier.

It’s big, green, and MEAN! Okay, maybe not mean. In fact, it seemed quite friendly.

The first step in installing the cylinder is choosing a location. I found builders electing to go with numerous variations, ranging from inside the baggage compartment to behind the baggage bulkhead, either mounted horizontally on the floor or diagonally on the side. I’ve also seen at least one builder mount it from the underside of a shelf that spans the area behind the bulkhead. In the end, I chose to mount mine on the bottom of the empennage, port side, behind the baggage bulkhead. I determined this would make it easier to remove than if it were mounted vertically or upside down. Plus, I planned to rivet part of the bracket structure to the skin and j-stiffeners using existing rivet holes. I felt that letting it “rest” on the bottom would be a bit more secure than “hanging” it off the side stiffeners, especially in turbulence. But I’m not a structural engineer so maybe it makes no difference.

I began by placing the cylinder and bracket assembly into the tail cone and positioning it nearly up against the rear bulkhead. I wanted to leave enough room for the regulator (which I estimated to be about 4 inches deep) behind the baggage bulkhead panel. (Note that Mountain High does offer a remote regulator option, which some builders have gone with. I’ve not yet decided one way or the other.) I aligned the cylinder to be roughly parallel to the two j-stiffeners and marked the position with masking tape. (I say “roughly” because the stiffeners themselves are not parallel and so I just “eyeballed it”.)

Plenty of room to get the fit I wanted.

Designing and Fabricating Brackets

I considered a few ways to fabricate the mounting brackets that the supplied brackets would bolt to. I thought about building a full shelf, but that seemed like overkill and a waste of material and weight. In the end, I decided to go with two longitudinal brackets riveted to the skin tied together using transverse crossmembers. Each bracket would include reinforcing bends for rigidity. Additionally, the supplied bracket dictated locations for nut plates that would receive AN3 bolts, so I had to decide exactly where these would land laterally. Because I also wanted to secure the fabricated brackets to the sides of the j-stiffeners (and thus needed to get a rivet gun or puller into some cramped spaces), I decided to position the port-side holes to the outboard side of the outboard stiffener and the starboard-side holes to the inboard side of the inboard stiffener. A final consideration was ensuring that I could get a bucking bar underneath the inboard bracket for the skin rivets. The additional clearance required also enabled me to level the mount laterally by varying the height of inboard and outboard brackets. With me so far?

Here’s a rendering of what I had in mind:

Note that the brackets aren’t perfectly aligned due to the angle of the j-stiffeners.

These design requirements led to me cutting out the following pieces of .040″ aluminum stock:

  • (2) 9″ x 2 3/4″ for the crossmembers
  • (2) 5 1/4″ x 3 7/8″ for the outboard brackets
  • (2) 5 1/4″ x 3 3/16″ for the inboard brackets

I choose 5 1/4″ for the length of the brackets because it enabled me to “capture” 5 rivets in the underlying j-stiffener.

I added 90-degree bends to the crossmembers to match the width of the supplied brackets and trimmed some of the material away in the center to provide clearance for the cylinder:

For the outboard brackets, I created bends that resulted in a 3/4″ vertical section flanked by a 5/8″ flange to match the j-stiffener on one side and a (roughly) 1 3/8″ flange for the crossmember attachment on the other. The inboard brackets have a 1 3/8″ vertical section in the middle, to account for the height difference imparted by the skin curvature, surrounded by 5/8″ and 1 7/8″ flanges for the j-stiffener and crossmember attachments, respectively:

Test fitting the brackets.

I clamped all the pieces in place and set the cylinder in position to check he overall fit. It seemed stable and well aligned.

Another test fit.

The next step was to attach the brackets. I started by flipping the tail cone on its side and drilling out the necessary j-stiffener rivets.

I’m the sure the original builder was very proud of these rivets. Too bad.

You can see from the photo that on the outboard one I miscounted and drilled out an extra rivet. This would come back to haunt me later when match drilling the brackets. I thought I was holding the bracket in the right spot, with my fingers out of the way, but ended up drilling through the bracket and into my index finger. Argh! Oh, well, time to update the board again:

I’m thinking about just using permanent marker.

Some antibiotic ointment and bandage later I had all four brackets match drilled.

Progress paid for in blood.

For the rivets tying the brackets into the sides of the j-stiffeners, I used a rivet spacer to evenly locate five holes using a #40 drill bit and then went back and enlarged them to 1/8″. I then clecoed the brackets in place and match drilled the crossmembers to them using a #30 bit. At this point, because I had a bit over five inches of bracket to work with, I elected to drill an additional set of bolt holes to provide for future flexibility if I didn’t like the position of the cylinder. Extra attach points would let me customize the position of the mounting straps against the cylinder body.

Happy with the fit, I drilled 3/32″ holes for the nut plates and enlarged the bolt holes to accommodate an AN3 bolt. I countersunk the nut plate attach holes for AN426-3 rivets then primed the parts and let them cure overnight.

The following day I assembled all the parts, starting with riveting K1000-08 nut plates to the brackets. I then riveted the brackets to the j-stiffeners and tail cone skin using AN426-3 and LP4-4 rivets for the bottoms and sides, respectively. The outboard brackets went on with little difficulty due to easy access to the rivet locations. The inboard brackets took much longer. For the blind rivets, I used sections of trailing edge wedge material to create a shim that provided clearance between the head of the rivet puller and the curved edge of the stiffener. It also turned out the space I allocated under the large bracket flange was a bit tight for me to get a firm grasp of the bucking bar. I resorted to using a wooden block to position the bar in place so I could then apply pressure with my fingers. In the end I was able to get the brackets attached, though I chose to drill out and redo a few rivets that I wasn’t pleased with.

Once the brackets were in place, attaching the crossmembers and cylinder hardware was straightforward. My hole locations turned out not to be exactly perfect but the flex in the bracket flanges helped to get everything aligned and bolted down.

Next up will be locating the fill port and starting the plumbing and wiring.

Build Date(s): 28-Jan-23 to 29-Jan-23
Build Time: 11 hours

I Just Gotta Vent

One of the earliest decisions I made on mods was to replace the standard rear seat vents with a ducted system supplying air to an overhead console. While quite a bit more complicated, it seemed like a more refined and upscale solution. Many other builders have gone down this road, which includes installing NACA vents behind the baggage compartment and running SCAT (or similar ducting) to a remote-control valve to control the airflow. This then feeds air into the console cavity where passengers use additional vents to direct air onto them as desired, similar to an airliner. In theory, you could dispense with the master valve, but I’ve read that the pressurized air in the overhead console can sometimes leak out, which is less than ideal with sub-zero OATs. Since I have been working on installing items in the tail cone before it gets rivetted to the fuselage, now was the perfect time to attend to this task.

I had long ago ordered the NACA vents from Van’s and, in a fit of muddle-mindedness a couple months back, had confused them with those that come in the finish kit and get installed in the forward fuselage, behind the instrument panel. Having committed to my confusion, I believed I thus possessed two sets of vents and match drilled them for riveting to the forward fuselage and set them aside. (Note that the plans call for securing the vents with ProSeal only but I, along with a few other builders, don’t trust the smelly goop and have elected to add some additional reinforcement.) When it came time to work on the rear vents, I spent more than a reasonable amount of time looking for the “other” set of vents before believing them lost and deciding to use the “forward” set. It wasn’t until later that I realized I had dreamt up the second set all along (the forward vents are not even the same parts). The challenges with getting old, I guess. Anyway, what was I talking about?

Let’s Cut Some Holes!

Ah, yes–installing the rear vents. The big decision with installing the vents is placement. Most other examples I’ve seen feature the vents installed centered vertically in the section of fuselage skin just aft of the baggage bulkhead, below the fuselage longeron. This is roughly on the same through line as the forward fuselage vent. Variations arise based on how far aft to go. Photos taken during my “research trip” to Oshkosh in 2021 provided numerous reference examples:

I decided to follow other builder’s examples and install the vent more towards the baggage bulkhead. This also avoids a sharper bend in the ducting, assuming you want it to stay in front of the next aft bulkhead.

To locate the cutout, I first created a template using scrap aluminum (cut from the forward fuselage tunnel when installing access covers) and tracing the cutout in one of the forward fuselage skins. I then drew centerlines on both the template and the empennage section and transferred the pattern to the skin, covering the skin with masking tape to protect against boo-boos:

As you can see, I located the forward edge of the cutout six inches aft of the empennage skin edge.

Next came the delicate part–cutting the holes. One reason I’d waited to perform this mod is the intimidation factor of cutting into perfectly good aircraft skins that are already part of the finished structure. If I’d been the original builder of the empennage, I would have done this prior to riveting the skin but, since I “inherited” the component, I had to execute the cuts in situ. Fortunately, cutting the template gave me a chance to practice on a (albeit thicker) piece of aluminum without consequence.

I cut the hole by starting with a Dremel and fiberglass cutoff wheel and finishing with a fine coping saw blade, a sanding wheel on the Dremel, and some files. I was careful to trim up to the line in increments. I then test fit the vent and marked any areas with too much overlap. The final hole closely matched the contours of the composite vent. From there I match-drilled the skin using the holes I previously drilled in the vents and gave the setup a test fit.

Some days later, (after finally deciding to prime the inside of the tail cone), I dimpled the skins and attached the vents using ProSeal and AN426 rivets. I followed Rodrigo Damazio Bovendorp’s lead and made some aluminum backing plates to take some of the compression from the rivets (though I elected to make these in two pieces, instead of one.

More Holes! More Holes!

The next step in the process was to cut holes in the baggage are bulkhead to enable air to flow into the overhead console. This was a bit tricky because I don’t yet have a console and thus needed to estimate the hole position. (The size is set by the vent flange from Van’s). By examining numerous photos and estimating the outline of the console’s rear profile relative to the bulkhead, I was able to choose two locations I believe should work. My fixation with symmetry placed one hole close to the row of rivets at the top of the bulkhead, with the opposing hole offset to be equidistant around the centerline. Was this critical? Of course not, given no one will see these holes in the finished product, but it made my overactive synapses very, very happy.

Because the tail cone had not yet been riveted to the fuselage, I was able to remove it and use a fly cutter mounted in my drill press to perform the cuts. I have read that some builders consider fly cutters to be possibly the most dangerous shop tool out there, with a razor-sharp blade that’s nearly invisible when spinning and just waiting to slice through a wayward appendage. However, I found it quite simple to use, even in a cordless drill, and the quality and precision of the cuts to be outstanding. You just need to go slowly until the blade just barely cuts through the material. The resulting hole is perfect and smooth (though the resulting scrap does tend to have a very sharp edge).

I also performed the addition step of flanging the holes to give them a bit more strcngth, given the resulting thinness of the bulkhead in that area.

Taking (Vent) Control

The final step (for now) was to figure out a way to mount the Aerosport Products vent valve. However, let me begin by saying I didn’t really want to use the valve, or at least pay for it. No offense to the good folks at Aerosport, but $300 seemed like a lot to pay for some plastic and metal bits, an R/C servo, and some electronics. I have played around with servos and controllers and was confident I could manage to come up with some DIY electronics. The question was the housing. I went so far as to design my own version from scratch in SOLIDWORKS and 3D printed some test parts. I even came up with what I thought were enhancements, including incorporating miniature bearings for the vent flapper rods.

I learned two things from my efforts:

  1. It was a very effective and satisfying way to teach myself 3D modeling in SOLIDWORKS.
  2. I have neither the time nor patience to fine tune a design for a one-off component I can just go and buy.

Well played, Aerosport, well played…

So, with the sound of a far-off cash drawer ringing in my ears, I started envisioning a mount for the (nicely done, BTW) Aerosport unit. As with other builders, I intended to mount it to the upper centerline j-stiffener, adjacent to the bulkhead flanged ducts. The challenge is that there is not much metal to grab onto. Some builders have repurposed other parts, like fuel pump brackets, but I wanted something more purpose built. I also wanted it to be easy to remove the valve assembly if needed down the road. I have also learned (the hard way) that it makes sense to plan out any complicated part(s) that I intend to fabricate.

That sent me down another SOLIDWORKS rabbit hole learning how to use its sheet metal functionality. I started by modeling the plate that would sit on top (or bottom, depending on which side you think is up) of the valve assembly and provide lateral support via two 90-degree bends. This required positioning two holes for the flapper rod caps. This would connect to two L-shaped vertical brackets that, in turn, would bolt to a third bracket riveted to the j-stiffener. I modelled each of these as a part in SOLIDWORKS and then pulled them into a final assembly (including a section of j-stiffener):

The virtual version looks so refined.

Note that I chose to model bolt and rivet holes but would locate and drill these manually during final assembly.

One handy feature of designing sheet metal components in SOLIDWORKS is that it can show a “flattened” view, making it easy to get dimensions of raw materials. This came in extremely handy on this project and I was able to get all the aluminum pieces (I used .040″ stock) roughed out, drilled, countersunk (for flush rivets), and bent in no time. (You can see in one of the images below that I used a shim to set the spacing between the two L-shaped brackets.)

I used the existing rivet holes in the empennage j-stiffener to match drill into the upper mount and drilled holes for additional AN470AD-4 rivets as well as screw holes in the L-brackets and valve assembly (no returning it now!).

After the primed parts were dry, assembly went pretty quickly. I riveted the L-backets together (using the spacer again) and screwed them and the bottom bracket to the vent valve assembly using AN515-8R8 screws and matching washers and locknuts. I riveted the top bracket to the j-stiffener using AN470AD-4 rivets (the top rivets will get set when the top skin goes on) and attached the top and bottom bracket assemblies, also using AN515-8R8 hardware.

Overall, I was pretty pleased. The mount looks well designed and has decent rigidity that should improve once the top skin is riveted in place, and the assembly is easily removable by undoing two screws.

Build Date(s): 22-Jan-23
Build Time: 7 hours

Wait! Did I Buy A Cozy?

With the elevator debacle under control I decided to sweep up the metal shavings and switch gears to Section 12–empennage fairings–one of the few tasks left to do. Section 12 covers the installation of composite fairings to elevator, rudder, and stabilizer tips. The molded tips come as part of the empennage kit but some must be modified by building up one side with raw fiberglass cloth. The plans are extremely basic, describing a two-step process through very clean-looking engineering drawings. Little did I know how much “character building” would be involved in saga that unfolded over the course of multiple weeks.

Some time ago I had ordered the composite practice kit from Aircraft Spruce. I ordered the version that comes with Burt Rutan’s “Moldless Composites Sandwich Homebuilt / Aircraft Construction” (a $15.50 value!), figuring it would be useful to learn from the master. For some reason this SKU was backordered (the kit with just the raw ingredients would have shipped immediately) and so it didn’t arrive until early January. When it arrived I wasn’t sure I’d made the right decision since the manual’s contents weren’t any more illustrative then what I can find online through EAA and YouTube.

I waited weeks for this?

Regardless, the kit came with everything I needed to get started, including West Systems resin and hardener, fiberglass cloth, flox and micro, cups, stirrers, gloves and more. The accompanying manual suggests several practice projects with which to get familiar with the materials and processes but, frankly, none seemed all that interesting. I suppose back when Rutan wrote the manual (apparently using a typewriter and ink pen) someone reading it would be mystified by this “magic” process. Today, when composite manufacturing is practically live-streamed (not only aircraft, but boats, custom cars, and more) you (or, rightly, me) feels like they understand what’s going on.

And thus I decided to jump right in.

The tasks called out in the plans are fairly straightforward and go something like this:

  1. Trim excess material to ensure the fairing will mate with the matching aluminum part.
  2. Remove any excess epoxy/gel coat from the joggle along the flange perimeter.
  3. Match-drill the fairings using the pre-punched holes in the aluminum skins.
  4. Dimple the skins and countersink the holes in the fairings.
  5. For fairings with an open side, enclose with three layers of fiberglass cloth and resin.
  6. Attach the fairings (except for the lower rudder fairing, which waits until lighting is sorted) using CS4-4 blind rivets

There are several considerations that affect the fit and finish of the fairings. Rather than provide a chronological narrative of the process (since that would result in a 70-page blog post) I will present some highlights of each stage along with lots of pictures as well as my observations, learnings and frustrations.

Mis en Place

As when making a great meal, each stage begins with prep work. First you must sand off any resin/gel coat in the “joggle” where the fiberglass parts get riveted to the aluminum structure:

Make the sloppy look clean!

I tried using a razor blade for the first few passes but this proved cumbersome and not all that effective. I found using a flat file much easier. Just hold the long edge of the file snug against the corner and work it back and forth until it’s square. It’s a bit hard to see in the image below but goal is to get a nice clean edge so there isn’t a gap when you rivet these onto the metal components.

The next step is to trim excess material from each part. I used a Dremel tool with a cutoff wheel as well as painter’s tape and a reference line to reduce splintering.

One thing to be careful of at this stage is the width of the flange. The plans specify a nominal width but I would recommend making it a bit oversize and then sanding to fit. Otherwise you risk not leaving enough material to support the rivets (see below).

Match-drilling and countersinking the fiberglass parts is pretty much the same as when working with aluminum, involving clecos, #30 and #40 drill bits, and countersink cage.

Where Are The Dressing Rooms?

One thing you might have noticed in the photos is that the fit between the rudder and rudder fairing was, er, not great. In case you missed it, here’s a close up:

Eeeew! Gross!

Oh, by the way, see that cleco right above the counterweight attach screw? The placement of that rivet hole is ambiguous in the plans drawings (note the lack of handy-dandy dotted lines below) but the text states you need to use an odd number of CS4-4 rivets and there does appear to be a hole drawn on the forward end so I assumed a rivet was needed there. If my rudder falls off because I misinterpreted the plans then now you know why.

18 lines, 19 rivets–the story of my life…

In retrospect I would recommend prepping the fairings while assembling the tail section components so you can check the fit and attempt any adjustments. However, because the rudder was already built when I got the kit I didn’t have that opportunity. My first thought was to attempt to improve the fit with some composite treatment. (I had never used composites before and so assumed they were effectively magic materials.) After stewed on the issue, though, I decided to try to improve the fit of the aluminum skins. Keep in mind this piece has to line up with the vertical stabilizer tip fairing and I determined just slathering on fairing compound was not going to provide the finish I wanted.

My fix involved removing the rudder counterweight, filling in the top screw hole as well as the infamous 19th rivet hole with JB Weld epoxy (using duct tape over the holes), clamping the skins tight around the fairing, and re-drilling the holes.

You can see how much the top portion of the rudder skin squeeze together (about 1/4 inch) the final photo above. You can also see a layer of JB Weld I applied between the two skins after reassembling the skins. Eventually all this will be covered with a layer of composite material.

Sometimes You Can Be Too Trim

The rudder fairing was the first piece I tackled and (naturally) I took off a bit material more than needed. To avoid having the fiberglass crack at some point in the future I borrowed a tip from another builder and patched in a thin strip of 0.020 aluminum using a strip of bi-directional glass cloth and resin.

Hold me tight and I’ll hold you tight (but not too tight)

You can see that I only added the aluminum to the forward sections where the flange was too thin for my liking. Also, the tips of the cleco clamps are wrapped in packing tape to prevent them from becoming permanent fairing accessories.

I made a similar mistake when trimming one of the h-stab fairings, cutting it to close to the end, right through a rivet hole.

Soooooo close!

In this case, though, because I needed to build up the open side with fiberglass, I assumed (correctly for once!) that enough material would get laid down to provide a reasonable anchor point.

Cutting in Three Dimensions

One of the challenges of trimming these fairings in particular is getting the upper and lower curves to align with the elevator fairings. You want to follow the contour of the elevator tip and fairing, leaving just enough space to ensure the elevator can move freely but not leave so much clearance that it doesn’t look pleasing to the eye. As with my aspects of the build, the solution is to work slowly, making small adjustments as you repeatedly attach and remove the fairing using clecos.

You can see above that before you close out the aft portion of the h-stab fairing with fiberglass it protrudes a bit outside the edge of elevator fairing. My solution to this was to make the temporary foam rib (see below) a bit taller than the profile of the h-stab fairing, thus “tucking in” the outboard curve.

R V Serious?

See what I did there? Subtle Latin reference. I crack myself up sometimes!

One of the most mysterious aspects of constructing the fairings involves enclosing the open side of the elevator and vertical stabilizer fairings with fiberglass cloth. The diagram in the plans that tries to explain this is deceptively ambiguous.

How hard can this be?

The first stab is to fashion a temporary rib out of foam and shape it to the fairing profile. I ordered some PVC Divinycell foam from Aircraft Spruce for this even though the composite practice kit came with some blue foam insulation pieces. I figured I might need it for other projects at some point in the future. At this point he plans are not very explicit as to how to go about forming the rib. Here are a couple of things that I took away from the process:

  • You can approximate the profile of the fairing by firmly pressing it into the surface of the foam.
  • Given the curve of the elevator counterweight, the rib should be made somewhat concave, not straight as it is shown in the plans.
  • Unless you like digging out pieces of foam and epoxy from hardened fiberglass, consider wrapping the temporary rib in packing tape. Argh!
  • Rather than making the rib flush with the back of the fairing as shown, recess it 1/8″ or so to provide a “well” to fill with fairing compound/micro-balloons. Argh again!
  • Make sure to test fit the fairing and attach with clecos until you are happy with the profile. Yay!

As you can see from the last photo, the first layer of cloth detached from the fairings in a few places. I figured this was okay because most of the strength was going to come from the two layers applied inside the fairing. As long as I was happy with the shape (you can see this in one of the photos) I decided to move on. Also, because I did not apply packing tape there was some foam residue on the inside of the fairings but, again, since this was going to be saturated in resin in the next stage (and no one except me–and, well, you–would know about it) I felt it was okay.

The next two layers of fiberglass cloth went on pretty easily, though getting it to lay down in the tight inside curves was a but tedious. Incidentally, even though the composite kit came with calibrated pumps for the West epoxy system I found it easier to measure the resin and hardener by weight (5 to 1) since I was working with such small volumes. I used a small digital scale I had bought for the kitchen.

Super-sharp shop shears (alliteration!) and a Dremel tool with cutoff wheel made quick work of cleaning up the excess cloth and resin.

This Page Intentionally Left Blank

After reinforcing the fairings the next (and last) step in the plans is to rivet them on to the appropriate tailfeathers.

Fiberglass, meet Aluminum. Aluminum, Fiberglass.

While the plans don’t dictate anything beyond this I have seen numerous builders apply composites to the joint between the two materials to make a more visually pleasing interface. In fact, the junction between the two components did look pretty amateurish. I contemplated leaving them as-is to reinforce to the FAA that this aircraft was, in fact, built by a total noob but, in the end decided to attempt to replicate my esteemed peers’ work.

In retrospect, I have to question that decision for the sake of my sanity. What became apparent quite quickly is something I’m sure builders of Long-Eze, Glasair and other composite aircraft are well acquaint with–the frustrating and fruitless hunt for smooth perfection. In a way, it is the definition on irony. I am building an aluminum aircraft, where subtle ripples in the skill and rivet lines are part and parcel, but somehow believed the tiny pieces of fiberglass at each tailfeather tip needed to exhibit the characteristics of the Hubble telescope’s main mirror. In case you are similarly afflicted I’ll briefly describe the high points here but, in truth, I am reluctant to relive this portion of the build.

I started by applying a layer of West Systems 410 filler to the individual parts in order to create a semi-smooth surface. I followed this up with a sanding and a layer of epoxy and micro-balloons. More sanding and a second layer of micro–followed by more sanding–yielded satisfactory pieces which I then riveted on to the main structures. I varied sandpaper grit from 80 to 220 and found these Durablock sanding blocks to be super useful.

Once riveted, I applied a layer of painter’s tape to protect the aluminum skin and repeated the 410-sand-micro-sand process to file and feature the gaps between the fiberglass and aluminum parts.

Once I had achieved reasonable good contours I hit the tips with a coat of SEM self-etching primer, which helped highly any ridges, valleys and pinholes. (It also offers a layer of protection to the layer of Alclad sanded off during the process.) Then it was back to spot filling with thinner and thinner coats of micro and more sanding.

In the end I was reasonably happy, if exhausted. Remember that gnarly gap between the rudder and rudder fairing? Viola!

Smooth as a bowl of ramen…or something

There was also a pretty nasty gap where the v-stab met the fairing that I was able to disguise.

Now, to see how it all goes together!

Fixing the Elevators


So after trying unsuccessfully to connect with my EAA Technical Counselor to come look at my elevator fiasco I decided to jump in the deep end and attempt a fix myself. After much thought and a few opinions from Van’s Air Force (including one that amounted to, “just give it a big ol’ yank”) I was pretty convinced the fix I had in mind would work. Specifically, my plan was:

  1. Remove the elevator counterweights
  2. Drill out all the rivets in the counterweight skins
  3. Using fluting pliers to impart a corrective bend in the end ribs
  4. Reattach the skins and counterweights

I started with the right elevator because it had the most interference, figuring if I could get that fixed the left one would be a piece of cake. (Yeah, right.) Step one, unbolt the counterweights. Step two, turn several dozen of the previous builder’s carefully driven rivets into metal confetti:

With the skin removed I had unfettered access to the end ribs and proceeded with bending them (to my will). I created a slightly exaggerated correction figuring that when reattaching the skin (using the same holes) would have a tendency to pull in back towards the h-stab. It did as expected after I clecoed the skin but did leave enough of a gap (3/32″) to resolve the problem.


From here all there was to do was to re-rivet the skins. This went pretty quickly thanks to the pneumatic squeezer I got from Cleveland Aircraft Tool. (I also got a t-shirt but this didn’t materially affect the process.)


Happy with my work on the right elevator I took the night off and tackled the left elevator the next morning. Oddly, even though I now understood the process it still took me about the same time to finish. Here’s a gratuitous time lapse of me drilling out the rivets:


In the end, I spent almost 10 hours correcting an issue that should have been done right in the first place. Happy days!

Elevator Pushrod

With the elevators themselves in limbo, I decided to move on to the elevator pushrod. In theory this is a straightforward step. You trim a piece of aluminum tube to length and then rivet in threaded inserts on each end. The aluminum tube is deceptively light and you wonder how it handles the stresses of control inputs. Of course, like an aluminum can, as long as it isn’t deformed in any way it has tremendous longitudinal strength. That means don’t dent it!

Second, you want to make sure to get the finished length correct. This is particular important with a piece like this one since, at 6+ feet in length, if you cut it short you’ll be paying as much for shipping as for a replacement piece. To complicate matters I had just broken my bandsaw blade and so needed to go “old school” with a hacksaw.

As is good practice whenever working with aluminum I measured the correct distance but then cut the tube slightly longer. I then set up some blocks on an adjacent workbench level with my sander. This would allow me to sand off the excess aluminum (being careful not to overheat it) until I had the specified length.

This ended up working very nicely. I measured several times as I was getting close to my mark and sanded a bit more until I had a perfect length (or at least as perfect as a my tape measure). You can see this in action here:

After sanding the pushrod to length the next step is to drill six equidistant holes for blind rivets. The plans provide an easy way to do this–cut a strip of paper that matches the circumference of the tube, mark the hole locations, then wrap it around the pushrod. It worked a treat! Now just measure the edge offset and drill #30 holes through the pushrod and insert.

As you may have noticed, the previous builder dispensed with primer on the interior surfaces. Again, I won’t get into the endless debate here. Van’s is typically indifferent but does recommend priming the inside of the pushrod tube since, once it’s rivetted, you have no way to inspect it. I took their advice and sprayed some self-etching primer in both ends. It was a bit difficult to confirm coverage but spray was coming out the opposite end and there was enough accumulation to swirl around the inside.

Additionally I thought the outside would just look nicer with a smooth coat of primer so I scuffed it with Scotchbrite (probably not needed with self-etching primer but did anyway) and cleaned with acetone. To get a consistent coat I fashioned some simple hangers from 1×2 redwood and nails clamped to a shelf protected with plastic. I got some drips at first but quickly realized they were being caused by ill-fitting nitrile gloves hanging over the nozzle. A quick adjustment and the priming was done.

After a few days of curing there was nothing left to do but make use of my new Ace Hardware rivet pulled and attach the threaded inserts, followed by some rod end bearings.


Elevator Attach and…Whoa!

Many builders look forward to the moment when, after months of diligent and careful work assembling numerous subcomponents, you get to Section 11. The title of the this section is brief and to the point: Empennage Attach. Like all sections, it begins with an overview diagram that conveys what you will accomplish by the end. The image associated with Section 11 tells the story. You will now assemble those numerous components into something resembling a real airplane (at least if you stand at the F-1006 bulkhead looking aft and squint your eyes). I feel kind of bad that this is one of my first tasks as the new kit owner and that the previous one won’t get to witness it (but don’t worry, I’ll get over it 😁).

One of the first steps is to attach the elevators to the horizontal stabilizer. Each is first attached by two rod end bearings secured with AN6 bolts, then you drill through the (very important) control horns, at which point both elevators are tied in to a common attach point. I was sweating this step because once you drill through the steel control horns you are, as they say, committed (in terms of geometry). Anyone who has worked with door hinges know that with two attach points you can get away with a little imprecision but with three everything needs to be lined up pretty closely. Such as it is with an RV-10 elevator. You are committing almost 11 feet of painstakingly and lovingly rivetted aluminum to two 1/4″ holes drilled using nothing but the central bearing as a guide. Screw this up and you will forever feel whatever wonkiness you’ve introduced in the control stick. Eek!


Fortunately I time to contemplate this most significant hole drilling exercise as the E-drill bushing (which is used to protect the central bearing from the nastiness of the drill) could not be located in the purchased kit inventory. Another order to Van’s and waiting for USPS was in order.

After the bushing arrived I decided it was time to forge ahead, the first step being to secure the horizontal stabilizer to a workbench “just so”. You position it so that the elevators hang over the edge of the workbench–all the better to test their range of motion.


The next step involves setting the offset distance of the rod end bearings to a specific measurement (7/8″), attaching each elevator, checking the edge clearances, and adjusting the bearing distances as needed. No problem!

Before I go on I want to point out that whomever decided to put rod end bearings in such a tight location (recessed inside the elevator skins) and expected someone to be able to adequately manipulate them must have been a masochist. After several clumsy attempts to adjust them using “off the shelf” tools (and mucking up the bearings in the process) I decided to search for a better option. I did find one–a custom tool for sale on line–but not wanting to (a) lay out more cash for a finished product and (b) endure the inevitable shipping delay. I decided to fabricate my own based on what I saw. So it was back in the truck and off to Lowe’s for raw materials.

One thing that has always appealed to me about the building process is that it will inevitably involve solving problems. (Keep than in mind–it becomes relevant again later in this post.) I do truly enjoy the process of being presented with a problem and having to stare, contemplate, theorize, diagram, experiment and (eventually) solve the riddle. For this particular conundrum I decided to fall back to my woodworking and plumbing experience and fabricate a tool that would do the job. It consisted of a plug made from an oak dowel (shaped using my drill press and small milling vise) and some PVC pipe.

With a handy new tool in, um, hand, I set about to satisfy the plans instructions regarding attaching the elevators. That’s when I had my first (only?) really big “WTF” moment thus far.

I was feeling pretty clever after figuring out how to support the port elevator so I could insert the AN6 bolts into each bracket, securing the rod end bearings into place, without assistance. Then, given the precision of modern, CNC-punched parts that Van’s produces, I expected to quickly confirm that the gap between the elevator end rib and horizontal stabilizer was a consistent 1/8″ as the plans specified. Well, not only was the gap not consistent, the forward tip of the end rib was actually binding on the h-stab. (As I said, WTF?!)

I won’t relay all of the thoughts that raced through my head at that moment (as some of them are not appropriate for a family audience) but suffice it to say I did pause and stare at the situation in front of me for some time as the stages of grief started to set in. The first phase, of course, is denial, as in, “wait, that can’t possible be happening.” I checked the plans and my work and indeed confirmed that the tip was binding. This quickly gave way to anger and several more curse words were uttered. Then the bargaining began. If only I adjusted this a little here and that a little there the maybe, just maybe…no. Actually I did get the tip to stop binding by backing the outboard rod end bearing out of its mount until it was hanging by just a couple threads but that didn’t seem like a structurally sound solution. After several iterations taking the elevator off, making adjustments, and putting it back on to no avail, depression set in.

Not ready for acceptance just yet I decided to try fitting the starboard elevator. Surely this was an isolated problem–or maybe I’d just misread the plans–and the second elevator would reveal the error of my ways. You can probably guess the result. It was a mirror image of the first elevator, if not worse. What was going on here?


I took a carpenter’s square and lined it up with the centers of rivets on the elevator’s longitudinal axis and attempted to also align it with the rivets on the end rib/counterweight skin. If you look closely at the images above you can see that, while the longitudinal rivets are perfectly aligned, the end rib rivets are askew, progressively getting worse as you go forward.

I shot off an email to Van’s and their response was, paraphrasing, “unpossible”. Well, yes, I agreed. If you follow the plans and align the pre-punched holes this should not be possible. We discussed potential ways to affect a fix, including longer rod end bearings and grinding down the edges. Neither seemed workable for various reasons.

Going back and reviewing the plans related to fabrication of the end ribs I noticed that it is up to the builder to straighten the ribs using fluting pliers. The skin is then clecoed to the ribs and the holes are match drilled. I speculated that the ribs might not have been completely straight and, after clecoing, might have put some sort of tension on the skins such that they developed a small deformation. Match drilling and riveting the skins locked this in. If you follow the plan’s assembly sequence you build up the entire elevator before fitting it to the h-stab so it’s possible the previous builder didn’t catch the problem.

So, what to do? I think the best solution is to drill out all the rivets that attach the counterbalance skin, remove the skin, and attempt to straighten the ribs, re-attaching the skins after that. This will likely involve replacing the skins since the existing holes would not align completely. Before committing to this course of action I decided to reach out to by build instructor Troy (who is also an EAA Technical Counselor) to get his opinion. I’m still waiting for him to take a look so, until then, this part of the build is on hold. Problem solving indeed!

UPDATE: Finally decided to forge ahead and try fixing the elevators.

Elevator Trim Servo Wiring and Test


With much of the tail cone already done by the builder I purchased it from I only a have a few options for things to work on until the next kit arrives (in a few months 😒). In preparation for attaching the tail feathers I decided to work on the elevator trim servo. In particular I wanted to (a) complete a bench test to ensure it works and (b) sort out how I was going to connect the wiring to the eventual fuselage and instrument panel.

The Ray Allen servo setup is pretty straightforward. The kit comes with the servo, a three position switch, and a position indicator display. The wiring diagram is also straightforward–connect the colors as shown.


Since I have previously dabbled in microelectronics I have no shortage of stuff for connecting components like this. One breadboard, a power supply and some hookup wire later…let there be light (emitting diodes)!


I ran the servo through its complete range and after confirming the servo electronics I moved on to the hardware. The first step was to assemble the servo linkage and it was then I ran into my first real aircraft builder decision. The plans call for the three pieces of the linkage hardware to be rivetted together using two AN470AD4-7 rivets but for whatever reason the remaining hardware that came with the kit contained but a single rivet of this specification. Now, being new to this whole every-decision-you-make-could-be-life-or-death thing I sought out some advice from the “hive mind” of RV aircraft building: Van’s Air Force. One respondent suggested I just take a longer rivet and cut it down using a rivet cutter. While I admit it’s a great suggestion I don’t (yet) own a rivet cutter. Not wanted to delay the process by ordering a single rivet to be delivered via USPS during the Christmas crush I decided to use a AN470AD4-8 (just a mere 1/16″ longer than specified). I figured as long I managed to create a good shop head I would be fine. The Cleveland Aircraft Tools “Main Squeeze” rivet squeezer made easy work of that.

The next step was to deburr the trim bellcrank and assemble everything. That’s when I ran into conundrum #2. The bellcrank mounts were too close together and I could not fit all the called-for hardware in the gap between the two angle pieces. With the holes in the F-1095A servo bracket already drilled I decided to drill out the rivets in one of the brackets and fabricate a new one. Fortunately the kit came with some leftover 3/4×3/4 aluminum angle stock and this went pretty quick thanks to band saw, sander and grinder with Scotch-Brite wheel.

Because I had all the hardware already out I sorted out the positioning by first drilling the 1/4″ hole for the bellcrank hardware, connected the bellcrank, and then match-drilled the three mounting holes using the holes in the servo mount as a guide. In the end it probably shifted the remade mount outboard about 1/8″ but that was enough for the bellcrank to move freely. Four rivets later (I screwed up one and had to drill it out) and the bellcrank was in business.


At this point I couldn’t help but wire up the whole assembly and watch the bell, er, crank!

I am curious to see how this all goes together since the forward bellcrank attach point dips quite a bit below the bracket and seems like it would interfere but, hey, after all these years I assume someone would have fixed it if it were a problem.

The next step was to create an attach point for the wiring harness I planned to build. I wanted to be able to (somewhat) easily remove the servo assembly as needed and so there needed to be a way to disconnect the wiring running up front. The servo lead wires are pretty short and so you need to route them to a point quite close to the servo. Based on prior art from Mouser I decided to fashion a bracket that would hold a CPC (see below) from .020 aluminum sheet.

I started by fabricating a cardboard template that would provide enough space for the connector and a tab that will be used to rivet the harness mount to the servo mount. I also added flanges to provide stiffness to the part.


I transferred the cardboard dimensions to aluminum and drilled out holes for the connector using a step drill and the mounting holes (not quite getting them aligned straight but, heck, it’s buried in the back of the empennage after all). Then I cut, sanded and deburred the final piece (being careful to drill stress-relief holes at the bend points) and bent the flanges in a vise.

I then had to decide where on the servo bracket to mount it. It needed to be close to the servo but could not interfere with the mounting screws. I offset it enough to provide clearance and then test fit the entire assembly in the empennage.

With the hardware sorted and connected I moved to how I was going to mount and route the wiring. As I mentioned earlier, I got the ideal to use CPC (Circular Plastic Connectors) from Mouser, and so did some research on them. I liked the fact that they are pretty foolproof and easy to manipulate in tight spaces and so, after shopping around, I ordered a bunch of components from

Now, all of those components are relatively inexpensive. What’s not inexpensive is the tool needed to crimp these particular connectors. At $200+ it seems like an extravagance at this stage but I see myself using these connectors a lot so I’m sure I’ll recoup my investment over time. (And, by the way, I also got the pin removal tool because I know I will screw something up at some point.) In addition to the specialty bits I also got some wire loom and silicone tape from Amazon and was ready to fabricate a wire hardness.


The first step was to cut the wire loom to length and thread the bare wires through. Of course I failed to recognize this as the first step and went ahead and attached the female sockets. This required carefully unrolling/re-rolling the loom around the wires. Argh…

Before I crimped the wires on the servo I tried practicing with some scrap wire, sacrificing a few connectors in the process. I found it a bit cumbersome to position the wire in the connector in the right way and also hold the two at the right spot in the tool. Also, the tool uses a ratcheting mechanism that doesn’t release until the connector is fully crimped so it’s nigh impossible to correct the alignment if you misalign something. Eventually I discovered that if I closed the tool until the first ratchet position I could maneuver a pin into the correct position and it would stay there. Then I could feed the wire into the open end and finish the crimp. In the end I got all five servo wires crimped without any screw-ups. Time to declare victory and go home!


Actually I forged ahead and finished the servo-side wiring by attaching the wire loom and silicone tape, inserting the pins, and attaching the shell clamp.

To finish out the wiring tasks I created a temporary wire harness to use during the install/adjustment process and tested everything on the bench. I only had one brief moment of panic when the servo didn’t work before realizing I’d inserted one of wires into the wrong row on the breadboard!


The final elevator trim task was to finish the E-616-PP trim cable cover plates, to which are rivetted a set of cable brackets. The previous builder had purchased a set of milled cable brackets from, but only after match drilling the holes using the stock Van’s brackets so these ended up as scrap. (Actually I ended up using them as #30 countersink guides.) Van’s brackets are nothing more than a nut welded to a piece of steel and if I had built the tail from scratch I would have upgraded as well.

For a reason never fully explained, he had ordered one replacement plate so one of my first orders placed to Van’s was for a second. Since, at that point, I had not transferred the project over to my name I’m sure the folks processing the order were perplexed why a “non-builder” was ordering this very specific part. A few days later I had my part and was ready to complete the step…until I realized I had somehow neglected to include a rivet puller with my tool order. Fortunately this is a non-aircraft specific tool so a trip to the local Ace Hardware store rectified the problem.

The assembly process went pretty quickly. It would have gone faster but it was the first time I got to use my dimpling table so I spent considerable time making sure I had the right dies, adjusting the table height and ensuring I was dimpling on the correct side of the skin.

Now, on to bigger things!