Project: TerryS     -     Entry

Mar 12, 2024 16 Empennage intersection fairings continued- & permanently installed VS & HS Category: Empennage
Over the last couple of days I've continued to plug away at this. Once I had the upper empennage faring fitting pretty well I moved on to the lower closeouts.

The way vans suggests you do these is to trim them to a 1/4" gap, then fill the gap with a piece of weatherstrip then tap the holes in the longerons and attach them with #6 screws. Way back during the initial empennage fit in the garage, I had blindly followed this process. When I trial fit them a few days ago I didn't like the way the weatherstrip fit and I certainly didn't like the way it looked. Just clunky. Because of the taildragger stance you can see it from anywhere in front of the airplane.

I went back to the print to refresh my memory and confirmed that there's a note which says you can skip the weatherstrip if you keep the gap to 1/32-1/16". I remade the closeouts out of scrap and spent quite a bit of time trimming the mating edge to conform to the lower skin of the H/S and they came out much better. I've got the bare minimum allowable gap here. At some point after flight test, I may lay bead of B2 in here to fill in the slight gap. That should be worth .01 knots of drag :)

I also elected to only tap two locations common to the aft inspection panel. I don't see why these should ever have to come off again, so I primed both mating faces and attached them with CS4 pop rivets. Quite a few people on VAF have done the same thing and have many years in service with no regrets.

On the aft lower corner of the upper fairing, you are supposed to drill out a rivet common to the fwd face of the aft double bulkhead and longeron and once again tap for a #6 machine screw. A thought on this; Standard practice says you don't cut fine threads in aluminum. because it's such a soft metal it's too easy to pull them out. I don't know why vans suggests this other than that it keeps the hardware callout simple.

I looked at this for a bit and after some careful measuring, determined that I had room to install a single leg nut plate through the skin just aft of the end of the longeron. I taped them in place and installed the rudder to make sure there was going to be room in there and that nothing would rub before I committed to drilling the holes.

The skin back there is only .025, but you have just (barely) enough thickness to countersink it for oops rivets to attach the nut plate without knife edging it, as you can see in the magnified picture of my test piece below.

This took longer than it should have, but I'm happy with how it turned out. The closeout strips are riveted on, there are only two tapped screws (at the top of the inspection panel) and the aft ends of the upper are secured where they won't be flopping around.

I installed nutplates for the upper empennage fairing, then permanently attached the vertical and horizontal with properly torqued hardware. Note- Looking at the forward H/S attach points with a mirror, it seemed like the bolts were a little long. I ended up adding a second washer to ensure The nut wasn't bottoming out on the shoulder of the bolt prior to achieving the correct torque.

I wrapped up the day by spending about about 4 hours today looking for the elevator and H/S fiberglass tips. I tossed the hangar twice, then drove home and looked all over the garage and basement, then back to the hangar in case I missed them. Gave up and cleaned the shop for a bit before coming home for the day, gave the garage one more look see and finally found them in a Tupperware tub that had gotten shoved behind a dog crate sometime in the last 2 years.

fitting of these will start tomorrow.


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