I took the time to address a minor issue with the tail fairing, where it was trimmed a little too much. Right under the leading edge of the horizontal stabilizer the fairing is designed to cover the gap between two sections of aluminum. I had trimmed it slightly too much and a small 1/8 gap had been created.
I took the fairing home and added some fiberglass and micro-balloons to build up the edge about 1/4 inch. A quick sand and spray with primer and I reinstalled the fairing. I used some more micro balloons behind the fairing, using tape to prevent it sticking to the fuse, and it came out with a perfect fit on the aluminum.
The original gap. This was the same on both sides.After building up with glass and filler, this was a final step to ensure a clean fitTidied up and primed
I didn’t have much time this week, but I was able to get the trim system working correctly.
Using the laptop and a long Ethernet cable I was able to use the VPX configurator tool on my laptop to send power to the trim motors. I was pleasantly surprised that both the roll and pitch servos worked correctly. I carefully verified that the orientation was correct. It would be easy to reverse either one. For example, the elevator trim tab moves up and down just like the elevator, but it has the opposite effect from the elevator itself. Pitching “up” causes the elevator trailing edge to move up. Trimming “up” causes the elevator trim tab to move down, not up. It moves opposite the elevator, providing a force that moves the elevator to change the aircraft’s pitch.
After confirming the motors were working, I was able to set the correct max, min, and midpoint settings for both servos.
I then worked on mounting the aileron trim brackets on the right wing aileron pushrod. These connect the springs from the servo control arm to the pushrod, actuating the aileron.
Aileron trim servo. The servo mounts onto the access panel at this point. Springs will attach to the holes in the end of the arm, and extend to the brackets on the pushrod. Diagram of the aileron trim system showing the springs and how they connect to the pushrod and servo armUsing the laptop to run the trim motors and to set the trim limit parametersVPX config tool. The whole electrical system can be configured and activated from the laptop. The blue Ethernet cable is a 50 foot cable that plugs into the VPX box behind the panelDue to interference between the springs and the pushrod, I bent the servo arm to gain some clearance Springs attached to the servo arm.One last picture before closing this up. Note, the d-sub connector is safety wired together
Over the last couple of weeks, Dad and I worked on the elevator and horizontal stabilizer fairings. Dad spent a lot of time getting the fairings to fit just right: trimming, glueing/glassing, sanding, and repeat. These fairings fit very well, and the gap between the HS and Elevator fairing is exactly where it should be. Dad was able to add a little curve to the aft edge of the HS fairing, which allows for a constant gap between the forward edge of the elevator fairing and the HS fairing, throughout the full range of elevator travel.
We also spent time sealing the area around the counterweight on the inside of the elevator tip, leaving one small exit hole on the aft end for draining any water that makes it into the elevator tip. Hopefully the sealant will keep any water penetration to a minimum.
Despite Dad’s near perfect fairing between the aluminum and fiberglass, once I started riveting the fairings, the rivets introduced a little bit of pillowing. It’ll need one more pass to fair it out before it’s final painted.
Test fitting the Horizontal Stabilizer fairingsAdding some curve to the aft edge of the HS fairing. The dowels are temporary to hold pressure on the structure Finalizing the elevator/HS gapPrimed and ready to be rivetedFinished.
With Dad’s help over the last few days we fit the tail fairings. This required some filling and sanding of the fiberglass fairing that fits between the VS and HS, as well as trimming an d fitting two aluminum fairings on each side, under the HS.
Part of the fitting process involved locating holes in the fiberglass to line up with the nutplates in the aft fuselage. Dad painstakingly measured the location of the holes before drilling them, ending up with a perfect fit.
I primed the parts alongside some of the other fiberglass fairings, and these are good to go now.
Keeping some tension on with a length of ropeDrilling holesDrilling holesFinal drilling holes in the fuselage, HS and VS. installed some nutplates as wellStarting the sanding Sanding complete, ready for paintInside of the fairing showing some of the filling that was needed to ensure a perfect fit
Today I torqued up the elevator counterweight bolts and used JB Weld to secure the nuts in place. This would allow me to remove the bolts (only one at a time), if necessary in the future. The problem with the original design is that the nuts are inaccessible under the elevator fairing which will be riveted into place. By gluing the nuts onto the lead weights, the bolts can be removed and reinstalled, and hopefully fully torqued, without needing to remove the fiberglass fairing.
Right elevator, showing the onboard counterweight, and the bolt heads that will be visibleLeft elevator, inboard counterweightRight elevator, outboard counterweight. This will eventually be covered by a fiberglass fairing. I may seal up the edges of the weight here to prevent any water from seeping throughLeft elevator outboard counterweightLeft elevator with JB Weld applied to glue the self locking nut and washer into place. I smeared Boelube on the bolt threads before applying the glue in case any got onto the threadsRight elevator with JB Weld appliedLeft elevator tip. This whole area is covered with a fairingRight elevator tip
I wasn’t happy with the way the wiring was running through the bottom of the aft fuselage, specifically, the chance of wires chafing on the ship heads of the rivets on the bottom skin.
To fix the issue I wrapped the wiring bundles in a protective layer of braided sleeving. This required removing some zip ties, installing the sleeve and the redoing the zip ties. It came out looking good.
Braided sleeve covering the wiring bundleBraided sleeve covering wiring bundle
Much like the VS, my Dad helped install the rudder fairings. The rudder came out looking great, with the light installed and some wiring and a molex connector installed too.
With my Dad in town, it was great to get his expert advice and handiwork with the firbreglass fairings. Being a boat builder back in New Zealand, my Dad has a lifetime of skill and experience working with all kinds of things including fiberglass. He’s a master at the stuff, so he went to work on the rudder and vertical stabilizer fairings.
The VS fairing needs an insert of glass on the aft edge and Dad made quick work of getting it made up and glassed in. the only real challenge was getting the fairing square. The piece is molded in two half’s then glued together, but there seems to be some slight misalignment of the halves casing it to be slightly lopsided. Dad got it pretty straight, so it looks awesome.
Today I officially finished section 10, the aft fuselage. With the empennage attachment finished, I completed the final step in section 10, riveting the forward bulkhead to the top skin rib.
I positioned the aft fuse on my work benches, and rolled it onto it’s side. By lying down inside the fuse, I was able to rivet 2/3 of the rivets using my new “main squeeze” hand rivet squeezer. The last rivet needed to be bucked as it was too tight against the skin, and the rib. Using a double off-set in my rivet gun I bucked it. Not my best rivet, but good enough.
Then I completed the aft fuse by screwing on the inspection port covers on the aft end. After I located the correct set of 16 screws, I had a frustrating time with a couple of the nutplates, where the screw wouldn’t sit squarely in the hole and wouldn’t engage with the nutplate. Withou the covers in place I was able to get the screws in, and that seemed to fix the issue. Covers are now installed.
Today was a big day, as I was able to attached the Vertical Stabilizer and hang the rudder on the aft fuse. I then added the elevators and finished up section 11. Well, it’s not really done, as there is some electrical routing that still needs to be done, but that can wait for now.
First I installed the VS attach bracket, then the Vertical Stabilzer itself. I used temporary fasteners, as this is all coming apart again soon.
Installing the VS was easy after the HS was finally installed.
With the VS on, I attempted to hang the rudder. Everything looked good except the gap on the top hinge was too narrow for the rod end bearing to fit. I took the rudder off and attempted to bend out the Ganges on the hing using a small wooden block. Measuring with my calipers, I found it to be about a millimeter narrower than the middle hinge. After several attempts, and with Jen’s help, I was able to get it to fit.
Installing the rudder took several iterations. The hold-up was an insufficient gap between the flanges of the top hung. Once I had widened these flanges, the rod end bearing slipped in perfectly
With the rudder on, I installed the elevators. This required supporting the tips of the HS so that the elevator counterweights didn’t cause the fuse to roll over as I installed these one at a time.
Amazing feeling to see all these parts come together. It’s a tangible reminder of the work I have put in over the last year.
With the elevators on, I measured the clearance between the rudder and corner of elevator and trim tab. It was 3mm more gap than the minimum, so I left it as-is.
Rudder swings free and clear, and clearances on the elevators look good. I could shave a small amount off the rudder stops, but I’m within 3mm of the minimum clearance, so will keep as-if for now.
