Tag Archives: prime

Rudder – Composite Tip and Beacon

Never underestimate the amount of procrastination required to get something done.

As usual, parts preparation takes most of the time. The fiberglass tip, as supplied in the kit, was a bit rough. There were quite a few voids and other imperfections in the layup. The trailing edge was too fat to fit nicely with the skin. Cutting and re-gluing with a bit of glass cloth and West 105 epoxy resolved that. The contour of the tip leading edge needed building up and shaping – requiring several passes. Epoxy takes hours to cure, so each step takes a day. Epoxy filler and wet-sandable primer attends similar time-sinking characteristics. Along the way, test fitting and match drilling of the mounting (rivet) holes was accomplished.

I didn’t really like the way the construction manual prescribed M4 rivnuts for the aluminum doubler that serves as the mounting base for the strobe. My concern is that rivnut installation might crush the fiberglass. I opted instead to make a new part that uses MK1000-06 anchor nuts and is riveted in place with AN426-3 solid flush rivets. Having the patience to eventually arrive at the decision to do this and then actually fabricating the mounting plate demanded all of the procrastination I could muster.

Copious foot-dragging precipitated the decisions about wiring and method of tip attachment. For some reason, I just didn’t want to shorten the (rather stiff) wire bundle of the Aveo Mini Max LED beacon. At the same time, I didn’t want the splice to be at or near the point where the wire exits through the bushing in the rib. A loop seemed the answer. And so it was. Final fitting of the tip to the rudder and pulling of the 3,2 x 8 mm rivets went well. I’d long struggled with the temptation of making the tip removable, à la Pascal Latten, by installing dozens of anchor plates, flush rivets and #4-40 screws, but my steadfast procrastination eventually paid off and the scales tipped in favor of just pulling rivets and being done with it.

Elevator – Counter Balance Skins and Composite Tips

Finishing the elevator was accomplished over a period of about 3 weeks. The composite tips needed repeated sessions of fitting, filling, sanding and priming to achieve a satisfactory appearance. The interface between metal and fiberglass part was dramatically improved from what it would have been, had I left the fiberglass parts untouched.

The fiberglass parts were built up, especially around the leading edge, with Poly-Fiber SuperFil epoxy filler to reduce unsightly gaps. It takes a day for the filler to cure before wet sanding with 400 grit 3M paper, followed by Rust-Oleum wet-sandable automotive (rattle can) primer and the better part of another day for that to dry. Patience is the key

Once I was happy with the fit of the tips, it was time to match drill the parts against the holes in the counter balance skins. That was quickly and easily done by hand with my lithium-powered hand drill and a #30 bit. I’d reviewed numerous discussions about how others attached their tips and decided to simply follow the construction manual, using the ordinary 3,2 x 8 mm domed rivets that were supplied with the kit. Done and done.

The elevator tips took a while to complete, but I didn’t get carried away. All-in-all, the results look rather nice – me thinks.

Elevator – Prep and Prime

Spring weather is here with luxuriously warm sunshine. I was able to get all of the smaller elevator parts Alodined and primed. The main channel parts had been done while my paint booth was still set up, before the QB delivery.

Once again, I’ve demonstrated that shortcuts don’t pay off. This time, I tried to skip scuffing the parts. I degreased, rinsed, applied Alumiprep 33 and rinsed again. But, my brush application of Alodine didn’t produce any measure of satisfaction. The results were blotchy and left places that just seemed bare. So, I went back, scuffed every square millimeter of every part with my trusty (red) Scotch-Brite pad. Then more degreasing with diluted Extreme Simple Green Aircraft, rinsing, Alumiprep, another rinse, more Alodine and a final rinse. Better this time.

Brush application of Alodine simply does not compare with dipping, but as a base for priming, it seems fine for good paint adhesion. If I was going to leave the Alodine treated aluminum un-primed, I think I’d have to go with dipping to get a more uniform “golden” appearance. There’s also un-tinted Alodine. I haven’t tried it. It might be hard to tell how effective the application is, especially given the primitive conditions and minimalist process I’m using. Stick with what you know.

My shop is full of wings and fuselage and my paint booth is now the great outdoors. It works well. I can paint more and in less time. There’s the added bonuses of not having to wear a body suit, a respirator or mess about with the ventilation fan. Good old Rust‑Oleum Self-Etching Primer in a rattle can is easy and effective.

I suppose it may seem silly to devote so much discussion to this topic, but I have spent more time on metal preparation than anything else – by far. It’s been terrifically time consuming. I think perhaps a future me might skip Alodine and priming of any next project. It’s certainly proving to be a lot of work. For this build, I’ve already come this far. Plus, the QB wings and fuselage were Alodined at the factory. Possibly, the effort will add an extra bit of long-term value. It’s satisfying, in any event.

Horizontal Stabilizer – Prep and Prime

I’ve temporarily set aside the rudder and moved on to preparing the parts for the horizontal stabilizer (HS), after finding a poorly formed rudder hinge bracket, about a week before TAF folks returned from holiday break on January 13. Once they were back and after a few emails and phone calls – TAF (USA) has a new part on the way to me.

The preparation processes for the HS are the same as I’ve detailed for the rudder (RD). Several days of indoor and outdoor work have all the parts ready for assembly.

We got some snow and for a couple of days, it got too cold in the shop for painting. Inside the shop temperature dropped to 42 degrees F – overnight. I really needed more than my electric 1500W ceramic and 1200W infrared heaters.

I made a good deal a small portable propane heater and was able to continue with priming all of the HS parts. In the morning, I can bring the shop up to 60 degrees F in just a few minutes.

Rudder – Prep and Prime

Preparing the rudder parts during the last few days of December and on into the first week of January 2020, involved increasingly familiar processes.

Inside the shop, deburring of all edges and holes was done with my Avery Speed Deburr tool and Scotch-Brite C/P 7A wheel. Light scuffing with a fine (red) Scotch-Brite pad seems to help make subsequent chemical treatments more effective. Initial parts degreasing was done by wiping with a splash of acetone on a paper towel.

Outside the shop, degreasing continued with Extreme Simple Green Aircraft Cleaner, using a soft clean rag, followed by a water rinse from the garden hose. It’s winter on the Olympic Peninsula and my well water is very – VERY – cold. My hands, wearing only thin nitrile gloves, are almost frozen. A few minutes in the shop to dry the parts and then it’s back outside to apply Alumiprep 33 with a silicone basting brush and freezing hands, while hovering over a black plastic mortar tub. Rinse, dry and repeat – this time with Alodine 1201.

It’s cold and it takes until the afternoon to get the shop inside air temperature above 50 degrees F. It’s something of a hassle to run my paint booth vent fan, as there are some gaps that let cold air in. Without the venting, I quickly and lightly spray just a few parts per day – often only one side. Then I have to abandon the shop until the next morning. It took several days to prime all of the rudder parts.

For me, degreasing and chemical treatments take hours and hours – most of it outdoors. I’m trying to use absolutely minimal amounts of material, not make a mess, and get satisfactory results. I just can’t afford to make or deal with dipping tanks. I tried to save time by not etching with Alumiprep. Unfortunately, I’ve found that even with thorough degreasing, there were places where the Alodine instantly sheeted off un-etched aluminum surface. Those parts got re-scuffed, etched and then re-treated with Alodine. I’ve tried not scuffing and short-cutting other steps – only to find that results tend to reflect the level effort that I put in.

The parts quality of the TAF Sling 2 kit is frankly remarkable – excellent in IMO. I could probably get away with little to no deburring – certainly much less than I’ve been doing. Priming is truly in the realm of optional effort. I’m taking it slow and having fun doing it all.

Somewhere on the TAF website there is a recommendation to start your building journey by ordering only the empennage kit and putting it together over a weekend – just to see what you’re in for. Maybe someone could take the parts out of the box – rivet them together over a couple of days – and end up with serviceable tail feathers. I suppose it’s mechanically possible, but highly unlikely, even for an experienced kit builder – if they haven’t previously built the empennage for some model of a Sling aircraft.

I believe a significant limiting factor of how fast you can go – is missing information detail. There are certainly a few pitfalls that only careful consideration will allow you to avoid. It takes time to understand. Achieving correct part orientation, relaxed fit and knowing exactly where and where not to rivet – is very important. If you get ahead of yourself, it’s going to take considerably more time, effort and cost for rework. Be careful. Strive to get things right on the first go.