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.
