Monthly Archives: May 2018

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.