I’ve continued to chip away at the never ending cabin top work. This is clearly the character building part of the RV-10 build. It’s hard to separate activities because the doors, cabin top, windows, etc. are all interdependent. There’s a notorious flat spot on the pillars between the doors and rear windows in the cabin moulding, for instance, which has to be built up to match the door. The front side of the window also has to be spaced out so there isn’t a sudden transition between the door, pillar and window. Can’t do this until the door is fully fitted though. The inside surface where the window is raised will need to be sanded back, so it isn’t different than the rest of the window interior. All of this could have been avoided if the cabin top moulding was fixed up, but Van’s won’t do this, hence the character building.
I trimmed all the windows down to size, using the last of the warm days so I didn’t risk cracking anything by trying to work it in cold weather. I used a dremel tool with a Permagrit wheel for all of the rough trimming, followed by a belt sander with 60, 80, 120 grit belts. When the windows were all trimmed to size I ran around the edge with a 240 grit belt just to be paranoid about removing any scratches. Cutting the windows causes sharp material to fly everywhere, like shrapnel, and it clings to everything. Glad I was able to do all this work outside.
I wanted to run electrical conduits up the front window pillars, but the problem is how to transition them into the Aerosport overhead. I didn’t want to build a front assembly that jutted out, restricting the view forward and upwards from the cockpit. So I 3D printed transition pieces in Nylon that go from the 16mm conduit into a fairly flat channel, and some corresponding channel pieces which when laid together continue the Nylon wiring channel back to the point of accessibility near the forward edge of the front overhead panel. Cut some slits in the front of the overhead, it’s all fairly unobtrusive. A few anchor points inside the roof for Adel clamps completes the wiring capability, so I now have a 16mm conduit from each side up into the overhead space.
With the conduits clamped, I tacked them in place with some dobs of epoxy. Once that cured, I sprayed fireproof expanding foam into each pillar, around the conduits. I then cut the cured foam down to form the shape I wanted on the inside of each pillar. Once the rest of the overhead and door work is done, I’ll do fiberglass layups over this shape. The foam is a bit rough in parts but it’ll be fine as a base to do the layups.
I have a set of Rosen front/side adjustable visors. At one point when the cabin and overhead were on I established the position I wanted the visor mounts, so that the visors just missed the front strut by about 1/4″ when pushed forward. I made an oval metal mount out of 0.025″ Alclad, with two 10-32 nyloc nutplates in the position of the visor mount screws. I oriented these so that they were minimally invasive in the front pillar, which forms part of the rollover protection and shouldn’t be drilled. These were tacked in place with flox, and the way they are positioned I’ll be able to make them merge in when I do the front pillar inside layups, with a bit of filling and sanding.
I drilled the overhead and installed nutplates for the metal inserts. Also did the cutouts for the vents. The carbon fiber is incredibly hard, I completely wrecked a 2″ consumer grade hole saw after just the four holes.
I 3D printed a drill guide for drilling the four holes in the front strut up through the cabin top. The guide worked great.
At one point when I was sick of fiberglass work, I modified the front seat rails, installing AN4 nutplates so that the seats can be removed easily by undoing two bolts, rather than having to take the rail lock off. This is a well known modification that means the seats can be removed in 2 minutes rather than 10-20 minutes of cussing.
Next step is to fit the door struts, and then take the cabin top out, install the overhead, and start on the layups and filling/sanding I need to do in order to finish the interior surfaces.
I managed to get the door latches worked out, after a fair bit of head scratching. The combination of kits works together well, just takes some patience to sort through the 3+ sets of instructions. I did various other bits of work with the doors – set the hinge positions properly with a layer of flox (left the washers that I had already set the position with in place), and epoxy’d some scrap pieces in position to cover over where the seal needs to go across the hinge recesses. I’ll fill and finish this with micro later on.
One of my awesome sons generously made me a pair of door pins, with points instead of flats, to help locate the position of the fuselage holes. He made them slightly larger in diameter than the Planearound pins, so that they were a friction fit inside the pin blocks – helping to make the hole location mark even more accurate. They worked great! I simply screwed them into the door in place of the Planearound pins, closed the door, and while holding the exterior of the door in the correct position, applied closing pressure to the handle to create a punch mark in the fiberglass. I then drilled these punch marks #40, #30, and then used a step drill to expand the hole to almost the pin size. I used a tapered hand reamer to finish each hole to size, taking off small amounts until the (real) door pins just fitted through the hole. Now the doors can be closed and latched! This sets the final door position all around, so I then final sanded to get the gap properly set to 1/4″ for the McMaster door seal. In a couple of places I had to build up the cabin surface about 1mm to close gaps that were too large.
Using the McMaster seals requires a 1/4″ thick edge all the way around the cabin door frame, and a 1/4″ gap between the door frame and the door. This gap comes from 1/16″ for the seal body, and 50% compression for the 3/8″ seal bulb. The problem is, the bottom rail of the door frame has to be built out to get to the 1/4″ gap, and around the rest of the door frame there is more or less a knife edge left after sanding down to the correct gap. I did two fiberglass operations per door in order to get the correct shape.
For the horizontal edge at the bottom, I cut a strip of 1/4″ Masonite, and covered it with packing tape. I also covered the bottom of the door with masking tape followed by packing tape, so there was no chance I could glue the door, Masonite and cabin top together. I roughed up the lower exterior surface of the cabin (which is concave and has to be filled), and then layered in a mixture of epoxy, flox and cabosil to just fill to the surface established at the top of the lip to be 1/4″. I had to cut some out in the middle to allow the Planearound gearbox shaft to get through. I then closed the door, clamped it shut, and wiped away excess epoxy that oozed out. This operation would be best done after the door pins were in place so the door could simply be latched. In my case I hadn’t done that yet, so I simply clamped the doors closed and used a few shims to ensure the Masonite was pressed firmly up against the top surface of the cabin, the surface I had already established as being 1/4″ from the door. After the epoxy set, I opened everything up, and except for a few voids that would need to be filled, the inside surface was smooth and correct. I then used a dremel tool with a Permagrit cutting blade and routing frame, and cut the top off this horizontal section of the door frame, down to just below the level where the Planearound gearbox shaft protrudes. Finally, I sanded the inside surface, and in some cases a bit off the outside surface, so that this bottom section was exactly 1/4″ from the door when closed (did this after the pins were in and door latched), and 1/4″ thick.
For the second operation, I did the remainder of the door frame in one step. I cut a piece of McMaster seal to use as a throwaway mould (after doing both door frames), long enough to do the top, both sides, and run along the bottom about 4″ each side. After final checks on the 1/4″ gap all around the door (the pins were done by this point so I could latch the door closed), I laid the seal down along a table, and filled the inside with epoxy/flox/cabosil. The mixture was not as thick as peanut butter, but just thick enough so that it would not run out after I pushed the seal in place. It has to be thin enough to be extrude-able from a ziploc bag, as shown in one of the photos. This is best done as a two person operation, I mixed two pumps of epoxy and started applying that while my wife mixed up a second lot. Once the seal was full of epoxy mix, we both picked it up. I had already marked the “centre” position of the seal and the corresponding place on the door. Starting at the centre, I pushed it into place and worked it around and down one side, then switched to the other side. Used a rubber mallet to make sure it was pushed all the way in. Cleaned off excess epoxy with paper towel, followed by paper towel soaked slightly with acetone. Make sure you lay a drop sheet inside the cabin before doing this! Then we drew another drop sheet across between the door and the opening, to prevent any chance of epoxy oozing out onto the door, closed the door and pulled the latch shut. This compressed the bulb of the seal and held the seal in position. After this, I did a final clean up and left it for a day. With the epoxy set, I removed the seal – which releases from the epoxy just fine – and was left with a perfectly formed lip around the cabin, the correct thickness and in the correct place. A bit of sanding to clean up is all that is required.
With this work done, and the overhead work which I’ll put in a separate post, I’m now ready to take the cabin top back off and do the layups and finishing required on the inside of the cabin.
Fiberglass hell continues (apart from two weeks off while I did an awesome flying trip) in the form of the two doors – an infamous part of the RV10 build. Each door comes as an inner and outer shell. You epoxy the two halves together, using the cabin top as a mold. Then you trim and sand each door until it fits. Sounds simple enough, but after installing the door, checking the fit, and taking it off for the umpteenth time it all gets a bit tiring.
There have been many incidents of RV-10 doors coming off in flight. Van’s released a supplement to the design, a “safety catch”, after the first few incidents. An aftermarket design from Planearound is generally regarded as the best solution. It provides a central gearbox with a CAM that “pulls the door in”, and 180 degree handle travel that provides longer pin penetration than the standard kit’s 90 degree travel. In addition, I’m fitting an external handle made by Aerosport Products along with a lock which is keyed the same as the baggage door lock.
I reviewed the information available about doors coming off in flight. The exterior of the door is a low pressure area, which tends to suck the door outward. The bottom of the door can flex and bow outward. If the door is poorly constructed, or if one of the pins is inadvertently not engaged properly, the door can disengage from the bottom and once that happens in flight, it is guaranteed to tear off around the hinges. Many RV-10 pilots never allow passengers to close the doors, electing to always do it themselves to ensure the door is correctly closed. Here is a list of what I’m doing during construction to avoid future door problems:
Install the Planearound safety lock (180 degree), instead of the Van’s safety lock. It seems overall a better design, there is greater pin travel and the centre cam lock doubles as a means to draw the door in so that the front and back pins cannot go anywhere but into their respective pin blocks.
Install four door pin proximity switches, which will act in series to switch a panel mounted annunciation light from “red” to “green” indicating all four door pins are correctly seated.
Adding some supplemental “stiffening” to the bottom edge of the door. To the extent the bottom of the door resists any tendency to “bow outwards” in flight, it is less likely to put stress on the door locking mechanisms.
Adding backing plates to the hinge mounting points for both the door and cabin hinge mounts. These came as a kit from Air Ward a long time ago. Not sure if I’ll use the exterior cabin support parts (since the standard screw heads are directly applied to the steel hinges), but for the cabin interior, which winds up hidden by the overhead, and the door interior, the support plates distribute the load across a larger area of fiberglass than four individual washers and nuts. Same for the door exterior mounting plates.
In addition to the above, I’m using an aftermarket bulb seal sourced from McMaster Carr. This seal is applied to the cabin side, and provides a more professional automotive style finish than the standard kit seal, which is applied to the door itself. There’s a bit more work though in that the cabin needs to be sanded down to a 1/4″ gap all around the door, and in turn built up to a 1/4″ edge all the way around to support the McMaster seal.
For the “additional structure” along the bottom of the door, I simply laid some 12mm conduit along the bottom edges in the inner shell, and secured it in a few spots with epoxy. In addition, I cut a handful of conduit sections, just under 3/4″ in length, and epoxy’d one end in place distributed around the large open areas of the lower door, as shown in the picture. When it came time to glue the two door halves together, I put down a couple of layers of glass across the conduits that ran across the bottom of the door, and then filled around it as normal with extra epoxy/flox/cabosil. When the two door halves were brought together, this created a “box section” along most of the bottom of the door. For the other open areas, I simply deposited a clump of flox on top of each short conduit, filling up the inside of each small conduit, and then securing onto the outside surface of the door once the halves were brought together.
I also pre-installed the Planearound gearbox and supports before the doors were glued together. I haven’t seen this done before. It means you don’t have to cut the bottom of the door open after the fact, and fill it back in. I simply drilled a hole in the right place on the inner shell, until the shaft just fitted inside the hole, then used the gearbox itself to match drill the four mounting holes, in turn countersinking these from the inside surface of the door. I pre-lubricated the inside of the gearbox with some Boelube, and then wrapped up the gearbox in packing tape, except for (a) some plain plastic on the rear under the packing tape so that the back of the shaft wouldn’t bind with the packing tape, and (b) the two rectangular holes in the sides of the gearbox where the racks go.
One concern is epoxy from the Parabeam draining down onto the gearbox, into the rack holes, and in turn into the gearbox – that would be a disaster. To ensure this couldn’t happen, I made up a thin Alclad plate which ran along the top of the gearbox, with a flange on each end. I epoxy’d this along the bottom edge prior to bringing the two door halves together. This means any epoxy that ran down after the door halves were brought together would drip down well away from the rack holes. I applied some thick epoxy/flox/cabosil mix along the top of this flange prior to bringing the door halves together, so that any (runny) epoxy from the Parabeam would tend to run away to each side rather than down the outer door shell. This all might be overkill, but it worked out OK because after the doors were cured, neither gearbox was seized up!
Gluing the two door halves together is definitely a two person operation. I had “Rosie” mixing up epoxy/flox/cabosil while I applied it. We both carefully placed the two halves together, and then onto the cabin/mold. I previously drilled #40 cleco holes through the door halves into the cabin. These are easily filled with (structural) epoxy later, and they allow uniform pressure to be applied while the door cures. Clamps can easily be over tightened, causing flat spots around the natural curve of the doors. After the doors were epoxy’d and placed on the cabin, I left for a two week flying trip, so there was plenty of time for the epoxy to cure!
The cleco’s came out OK, some requiring a bit of twisting and force to remove them due to the epoxy running down into the cleco/holes. It took around eight hours per door to trim off the excess and sand down the edges to match the cabin top. I used duplicator straps to keep the door alignment left/right during this step, and one on each top corner. I highly recommend the latter – four straps in total – because the top edge of the door is where you start the final fitment, this is where the hinges get drilled. Once the door is on the hinges, it hangs slightly differently because there’s more weight towards the front of the door than the rear (the hinges are not in the door’s C of G), so you can’t trim the lower parts of the door until the hinges are fitted. It’s all a bit of a chicken and egg problem, but after having each door on and off about 20 times the doors are a good fit. I only took enough off the doors to have them fit into place, more sanding will be required after the cabin top is properly fitted to the fuselage in order to set up the gap all around each door.
After all that, I have each door now hinged to the cabin, and quite an accurate fit, the bottom edge of each door is less than 0.5 mm proud on the front and back edges, and perhaps 0.5 mm under in the middle. Ultimately the transition from the door to the fuselage will have to be filled and sanded all around, along with the transition into the cabin top, so +/- 0.5 mm is good enough for now.
The doors (and cabin top) are a long part of the project. I have quite a way yet to go with them, but the weather’s been good so almost all of the sanding I’ve been able to do outside.
Notes from the future for builders:
Don’t drill the bolt holes around the lower doorway from the cabin top into the fuselage, just drill #30 holes on the side and #40 holes on the bottom. You’ll want to remove and reinstall the cabin top on multiple occasions while you work on the doors and overhead/interior, and it’s much easier to use cleco’s than bolts. Enlarge these to the required bolt holes once you’re ready to final install the cabin top.
If you’re going to use the Planearound kit, definitely install the gearbox onto the inner door shell before gluing the two door halves together. For the 3/8″ access hole required – use their measurement for the distance forward from the gearbox, but for the up/down distance, don’t measure it – insert a rack into top side of the gearbox, roll it forward until it intersects the “vertical” line you just drew for the forward distance, and use the hole in the rack as a drill guide to drill a #40 hole through the door. That makes a pilot hole in exactly the correct position, now enlarge the hole to 3/8″. Later on, place some masking tape over this hole while sanding the door, you’ll be creating clouds of fiberglass dust and there’s no need to have that accumulate inside the door or gearbox.
If you’re going to use the Aerosport exterior handle, pre-drill #40 the three holes using the stainless steel striker plate as a template, through both the inner and outer door shells, while the two door halves are all cleco’d together for initial preparation. This is the first step in the Aerosport instructions. Why? Because when you glue the doors together, you can install three #40 cleco’s (could use #30’s) through these holes and that brings together the two surfaces where the door latch mechanism goes. The instructions tell you to coat these surfaces with regular epoxy, but that is fairly runny and once the door is placed on the cabin for the epoxy to cure, the epoxy can run and a poor bond can occur in this area. This happened to one of my doors, I had to use a syringe to squirt more epoxy into it while installing the latch, and this shouldn’t happen. In fact I’d put a thin layer of the thickened flox on this area in the first place, slathered on top of the thin straight epoxy which will run.
Use plenty of the thickened epoxy, and remember on the aft side and the bottom that the final trim is quite close to where the two shells part. Be generous with the amount applied, you need to work fast and there’s no point in trying to economize on the amount of epoxy (it weighs next to nothing) or focusing on making the application pretty.
My formula for the thickened epoxy was 4 pumps of epoxy, 4 pumps of slow hardener, 2 scoops of flox, and 2-3 scoops of cabosil. Mix the epoxy and hardener thoroughly first, then mix in the flox, then mix in the cabosil, until the mixture does not slump if held vertically. We made up 3 of these per door (in addition to the regular epoxy used for the Parabeam). Might have been a 4th on one side, can’t quite remember.
Next job is to install the door latches, which means rationalizing three sets of instructions – from Van’s, Planearound and Aerosport. Fortunately, plenty have gone down the same path before me, so between these instructions and some online reading I should be able to work it out.
In the context of the Fuselage build plans, I’m up to section 36 – brake lines. That’s followed by fuel lines, rudder pedals and brake system, control system, flap system, upper forward fuse installation, rear seats and then the cabin cover, doors and windows. I’ve decided to change things around a bit and work on sections based on the weather. I don’t want to be working on the cabin cover and doors over winter when it’s cold and miserable working outside, and fiberglass doesn’t set enough overnight to be sanded the following day. So, I’ve started on the cabin cover. I’m going to work on other sections during the times when either the weather’s a problem, or I just can’t stomach doing fiberglass work.
I also need to paint the interior. This made me think about eventually painting the exterior. I decided to buy some topcoat, in a dark grey tint, and use the interior as a means to learn how to shoot it. The first test pieces were a disaster. On a hot summer day, there was so much moisture in the compressor air, it totally overwhelmed the water trap in my filters. To fix this I built a heavy duty water trap, consisting of 18 metres of 1/2″ copper tubing, immersed in cold water. I built it in a wheelie bin, with incoming (hot) compressor air tapped in near the bottom of the helical tube. A drain valve at the very bottom of the tube can be manually opened to release accumulated water. The cold immersion water comes from my bore pump, 75 metres underground, so the water is always cold. I turn the water feed on whenever I spray, and the outflow just drains into open ground in a paddock. As the hot compressor air cools, water condenses and runs to the bottom of the helical copper pipe. The outlet at the top of the pipe feeds into the regular three stage air filters (which I replaced). I also installed a final water trap on the belt regulator. This resolved the water problems and greatly improved the spray job. I still had a bit of silicone contamination, from my priming habit of using syringes (which are lubricated with silicone oil) for de-greasing solvent. I’ve ordered some materials to do a better job of cleaning, so we’ll see how that goes.
I built the back seats, they were easy and are in the spray booth ready to prime.
I built and installed the flap system. The drop saw with the blade I use for aluminium cutting worked well for trimming the UHMW bushings. I was a bit concerned about drilling the safety wire hole in the flap motor, but that turned out to be a non event. I forgot to final ream the 1/4″ holes in the flap crank, and had to use an angle drill to get down into the tunnel and clean the holes out after the components were assembled. I could have disassembled everything but that would have taken longer.
To trim the cabin cover, I used several different tools. My ancient jigsaw with a perma-grit blade worked a treat on the open sections. For trimming the door openings, I used the van’s supplied cutting blades in a die grinder for some parts, and a perma-grit circular cutter in a dremel tool for others. Plus a belt sander with 80 grit paper, and several different perma-grit hand files. The Van’s scribe lines weren’t much use. I used a series of measurements, triple checked it all, and cut to the measurements. I was able to get the cabin cover to fit in place on the second attempt. It came off and went on a few more times to adjust the sides and rear deck, which turned out to be a bit long and had to be trimmed.
I decided to drill everything #40 to start with. This way, I didn’t have to open up as I went to remove shavings from between the canopy and the skins. It also makes it very easy to drill the rivet backup strips. I match drilled #40 from the cabin cover to the rear backup strip. For the side rivet backup strips, I simply placed them on top of the longerons and match drilled from the side skins – easy. Then I re-installed the cabin cover, and cleco’d everything up including the rivet backup strips with #40 clecos. With everything installed and cleco’d, I then went around and final drilled #30, again not needing to clear out shavings.
I’ve got a long way to go with the cabin cover and doors.
Today I finished the baggage door. There’s a problem with the RV-10 baggage door. The top surface of the door structure has a curve in it, which doesn’t match the fuselage. The plans instruct you to build the door on the bench. If you do this, it may not fit very well, and it’ll bulge out about 2mm due to the mismatched curve problem.
I got some advice on these issues, and built the door on the fuselage, forcing it into the fuselage shape while riveting it together. I built the door from the hinge out, and it worked out really well. In addition, like many builders I arranged the hinge pin as two halves, which can be inserted from the inside, making the baggage door easy to remove. This also allows the hinge to be set almost flush with the fuselage, rather than protruding out as the plans indicate (since in the standard plans, the hinge pin is inserted from the outside).
Riveting the outside skin of the baggage door is a bit awkward. I managed to slip once and put a very slight dent in the skin near the hinge line. This is easy to fill prior to painting, annoyed me a bit though because it’s the first rivet gun blemish on the entire fuselage.
I’ve now done enough to the fuselage to paint the interior. Before doing that I have to make a water trap to properly dry the compressor air before the filters.
I’ve been working on the baggage area and rear seat floors, and associated systems including wiring conduits, extra inspection covers and A/C hose routing. This work has spanned a number of sections in the build manual, there are a lot of inter-dependencies and I spent weeks hopping around while seeming to make little progress.
In the end I wound up with a large pile of parts to prime, and once that happened a lot of assembly to do. I’m near the end of all the assembly work and must have made some progress here because non-flying people who look at it now recognize it as an aircraft!
Here in no particular order are some notes on some of the non standard items:
Added inspection covers for the steps, as is commonly done.
Added access covers for the antenna positions, so that I can install or uninstall the COM antennas that are mounted under the rear seats.
Made a lot of 3D printed parts to support conduits. Some out of Nylon, some out of ABS. These worked out great.
Ran the required A/C hoses to the positions in the tunnel where the connections to the A/C condenser are made.
Ran a bevy of electrical conduits, overkill probably but at least I’ll have plenty of capacity for wiring front <=> back.
Ran the static line
Added a small hinge piece for a POS-12 based flap position sensor
Added some extra nutplates for Adel clamps to support wiring through the flap torque tube area.
Added conduits from the flap torque tube area down to the rear of the baggage area
Overall a lot of work to get to this point. A slow build RV-10 is a big project.
One other work item – we assembled the Aerosport seats and couldn’t resist putting one in on its slides to see how it looks. Picture below.
The tailcone attachment is done. I wound up spending a very large amount of time preparing items that needed to be dealt with prior to attachment, including battery mount modifications, avionics shelf supports, a yaw damper servo bracket (modified Van’s RV-14 bracket), but most notably the A/C evaporator shelf, inlet air and bulkhead outlet air (into the overhead). Many hours of design for the 3D printed parts involved in the A/C system, which will be the subject of a separate post.
In the meantime, I fitted doublers for the ADS-B antenna and A/C drain pipe, and finally fixed a dent in the side of the empennage where, a long time ago, I dropped a bucking bar. I used the “packing tape and spoon” method to work the dent back in, and then drilled a #40 hole right on the peak of what was left in order to de-stress the area. I then dimpled the hole and back riveted an AD3 rivet into it. Once painted, an astute observer might notice a rivet in an odd place, but otherwise the panel is fine now.
I fay sealed the attachment skin overlap with some Sikaflex Pro. This makes for a few nerves because it means once the assemblies are slid together they really need to be riveted in one long session. We did this with no real dramas and only one drill out. At this point in a slow build project, “Rosie” and I really have our act together and riveting goes quite quickly.
With the tailcone attached, the next step is to fit and match drill various floor panels.
Another long building delay is over. I went to Osh Kosh, traveled a lot, looked after ill friends and family, and did some consulting work. Now the weather is improving I’m determined to get the project back on track.
I finally finished the empennage fairings. Spent way too much time fiddling around with the horizontal stabilizer tip fairings. That’s now all behind me, except for some fill priming. I’ll probably put a layer of glass tape across the HS tips to metal transition, just to ensure there will be no cracking in that area.
With that all done, it’s now time to attach the empennage to the fuselage. We lifted it into place, and everything fitted really well. After a match drilling session, it is now time time to take it off, debur, prime a few parts, and then attach it permanently.
It’s time to dig out the empennage and start some preparation for attaching it to the fuselage. I have to take the tail feathers off, but before doing that it’s best to deal with the empennage fairings – can’t put off fibreglass work any longer. As supplied the fairings require some trimming, and in general fit reasonably well but far from perfect. Here’s what I did to each part:
The elevator fairings – I didn’t like the uneven gap around them, and the front side had a gap in the centre of about 2mm. I used good quality 3M electrical tape as a release agent, scuffed the sides and front of the fairing, and applied a mixture of West Systems epoxy and micro-balloons around the exterior with the fairing cleco’d in place. Once this set, I sanded off the excess micro down to the tape, removed the fairing and then removed the tape. I had to repeat this operation in a few sections. I also epoxy’d a narrow strip of 0.025″ Alclad around the interior along each rivet line. I decided to use nutplates to attached the elevator fairings, so they can be detached if I need to adjust the elevator counterweights, so I used #6 nutplates held in place with NAS1097 rivets. I dimpled the elevators with #6 die, and used countersink #6 screws to complete the assembly.
For the bottom rudder fairing, I used the same method. I also added a metal backplate into which I can screw the tail-light.
For the top rudder fairing, I added the interior Alclad strip as well, even though I riveted it to the rudder. I didn’t like the idea of the rivets cracking the fibreglass as they were set. The front side of the top rudder fairing had a significant gap, which I built up with a layer of glass and flox, and finished with micro. I continued a thin micro application right across the front surface of the rudder balance arm, since this is a permanent attachment.
For the horizontal stabilizer fairings – I trimmed them, and using a balsa-wood insert covered in packing tape, applied a layer of glass and then two internal layups. After trimming I used some micro to build the edges back up a bit for the nominal 1/8″ clearance, with a concave inner surface that the elevator counterbalance arms can swing across.
The empennage fairing – I covered the tailcone, HS and VS surfaces with packing tape, layered flox along the surfaces where the fairing rests on metal, and cleco’d the fairing in place. I did this in two parts – the horizontal sections first, then after release and cleanup, the vertical stabilizer. The flox released OK, and to clean the packing tape residue off the metal surfaces I used Eucalyptus oil followed by Acetone. I then trimmed the fairing down to the trim lines, first with a Permagrit dremel cutting wheel, and finishing off with a sanding disk in the die grinder. I also trimmed and sanded any excess flox that had run down across the interior of the fairing. The end result was a fairing which fitted tightly against all surfaces. I’m going to fill some of the screw holes, with the fairing properly fitted like this it is not necessary to have as many screws along each edge.
Now I have a lot of pinholes to fill. I plan to do these with the epoxy / squeegee method, then will apply a coat of epoxy primer followed by a fill primer to complete the surface work. Overall the fairings have been quite a bit of work, spread out over several weeks. Weather is cold at present, and even using the “fast” hardener I’ve sometimes had to leave a heater on in the workshop overnight to get proper curing of the epoxy.