12: Empennage Fairings Complete

I left the Emp fairings at the stage where the high build primer had been flattened and levelled, and they were ready for a "final" coat of primer :)

To recap, I posed a question (which will be answered below).

I am toying with the idea of skipping straight from the microlight filler step, to the high-build primer step. This is because this particular high build primer is almost as hard as epoxy, and i think i should be able to sand it back to fair without needing the epoxy skim coat underneath. Will report back soon!

Here are the pics of the fairings after a coat of Stewart Systems EkoPoxy (the same primer i am using on all the metal parts).

As you can see, there were a number of places where i had sanded through the high build epoxy into the micro underneath and also a few small places where this had occurred on the parts which had the skim coat of epoxy applied.

To answer the above question: the addition of the skim coat step really makes a difference to how many pinholes you end up with. The parts which had the skim coat had many many fewer pinholes overall. I think the skim coat is a good idea and in fact i might even skip the high-build primer altogether: just apply the skim coat (but maybe 5 coats and not 3) then shoot the Stewart Systems from there, and fix any remaining pinholes with blade putty (see below).

Filling Pinholes

So how do i fill all these pinholes? As it turned out, this was an easy affair. My TC recommended the following single pack product for these very very small imperfections:

The imperfections were marked with a chalk pencil, then a razor blade was used to very lightly fill all the pinholes. 

Once this was dry, it was sanded off wet with 800 grit, then another coat of primer was applied. After the second coat had cured, they were again sanded wet with 800 grit and came out as follows. I was very happy with the final result.

Fitting the fairings - FINALLY!

Finally, the fairings were complete and able to be fitted. This was a simple task of following the plans. Match drill each hole to #30, remove and deburr the aluminium skin, and dimple. Then the fairings were countersunk for the dimples, and deburred. Finally they were riveted on with CS4-4 rivets as called out in the plans.

Countersinking the fairings - the aluminium strip which was epoxied inside, stopped the pilot from wandering. 

Skin dimpled...

Top of the VS / Rudder. 

I was happy with how this turned out - i used a bit of flox inside the top of the rudder to fill a tiny gap at the trailing edge.

The money shot!

Right HS / Elevator Fairings

Left HS / Elevator Fairings

VS / Rudder Fairings

Rudder Lower Fairing

The rudder lower fairing was trimmed as per the plans, with quite a bit of sanding to get it to fit with the trailing edge. Nutplates were installed and the fairing was countersunk for the screws (and i used CA to harden the countersinks where the screws will sit). I trimmed the fairing before i marked where the modification for the tailspring is supposed to go, so i was not able to locate the cut template properly. I decided to leave that modification (and the finishing of the fairing) until a later date when i have the tailspring on hand and i can modify the fairing to match the angle of the actual tailspring (instead of guessing with the template). 

Trimming the fairing to fit using a Dremel and a cutoff disk

Trimming to fit around the rudder horn

Match drillled to the attach strip

Match drilled to the attach strip

The fit around the rudder horn came out nicely

The rear needed a lot of sanding to look nice and match the width of the lower rudder trailing edge skin. I ended up adding some flox on the inside as it became a bit thin in a few spots.

After sanding to match

After sanding to match

To attach the fairing to the attach strips, i made a nutplate jig by screwing a screw into a nutplate then cutting off the head of the screw. This could then be used to match drill the nutplate attach rivet holes.

Making a nutplate jig. 

Nutplate in position ready for match drilling the attach holes. 

Nutplate in poistion ready for match drilling the attach holes.

I held it in place, drilled one hole, then cleco'd that, then drilled the other.

The fairing was countersunk for size 6 screws, then CA used to harden the countersinks.

Installed for now... 

Empennage Gap Covers

Since i had the tail all assembled for the glory shot for the fairings, i decided to fit the empennage gap covers at the same time. These were relieved about 1/32" from the skin so they didn't rub. The holes were match drilled at the top from the VS, and the aft hole was expanded for a screw at a later date. I will dimple this once the part is primed. 

The gap fairing as seen from below

Approx 1/32" clearance from the HS skin

The top side of the fairing. 

The fairing which covers the gap between the VS and the HS comes with the finishing kit - so i am unable to complete that at this time! 

The End! (sort of)

So that officially concludes all jobs i am able to complete on the Empennage Kit. The first day of working on this kit was the 5th July 2018, and the last day was 30th March 2020 - 1 year, 8 months and 25 days! (Certainly not the fastest builder out there) - however i only worked on the kit in this time for 161 separate days (life / work argh!). During this time i spent 402 man hours on the kit, for an average of 2.5 hours per session. The total days to compete the kit was 634 days - meaning a real work rate of 0.63 hours per day. Guessing a total of 2,500 hours to complete the kit, this means at this work rate i should be finished by 1 Sep 2020!!!

There were grand total of 4,968 rivets installed in the Empennage Kit.