May 01, 2024     24-02 - Wing Tip Flange Trimming - (6.7 hours)       Category: 24 Wing Tips

Initial Prep (Debur, Trim, Drill, and Cut)
2/24/24 - 1.2h
4/28/24 – 3.8h
4/30/24 – 1.2h
5/1/24 – 0.5h
This is my first foray into the world of fiberglass parts, so I was very hesitant to jump in and begin. I'm to the point, though, where the garage is starting to feel a bit cramped and the wings may have to be relocated to a storage location soon, which means I need to get at least the rough work on the wing tips done. The good news is this is just the first chapter in a longer wing tip book. No special skills are required other than a little care and patience (like everything else!).

The first step is to trim the edges of the wing tips leaving a 1/2" flange. The wing tips have indented flanges molded into them, and I used a roll of 1/2" wide electrical tape to measure the edge of the flange. That turned out to be a good approach – just cut and sand up to the tape, and the result is a decent 1/2" wide flange. The plans don't explicitly say how far aft to cut, and the indentation in the mold ends approximately where the top and bottom wing skins end. Go ahead and continue the tape in a straight line all the way to the trailing edge, and cut the edge of the wing tip down to the tape around the entire wing tip. The aft portion of the wing tip will get some additional cuts later, and cutting the entire wing tip even now is easier and makes later cuts easy, too. I used a Dremel and plastic-cutting wheel to trim the wing tip edges, and then took a small hobby file followed by 120 grit sandpaper to clean up the entire cut to the tape edge.

The wing tips can be loosely test fitted into the wngs at this point to locate the aft edges of the top and bottom skins on the wing tip. All of the cuts from this point forward are referenced to the aft skin lines.

The next cut was a little confusing. The plans say to notch the bottom flange of the wing tip 1/8” deep up to a point 1/2" forward of the aft edge of the bottom skin. The purpose of the notch is to allow the wing tip flange to clear the aileron hinge bracket. The key phrase there is “clear the aileron hinge bracket”, not the aileron hinge itself. The aileron hinge bracket is riveted to the aft edge of the outboard wing rib with the forward portion of the bracket extending about 1/2" forward of the bottom wing skin. Cut off the 1/8” wide portion of the bottom inboard wing tip edge starting 1/2" forward of the aft edge of the bottom wing skin all the way to the trailing edge. You can also cut off the 1/8” wide portion of the top inboard wing tip edge starting at the aft edge of the top wing skin to the trailing edge.

The final series of cuts are to allow a minimum 3/16” clearance between the wing tip and the aileron. I made a series of 1/16” cuts to the aft portion of the wing tips until I got about 2/16” clearance. I'm going to leave that clearance for now, and come back later with some finer grit sandpaper to open up the gap and smooth the edges. That will be in a later chapter of the wing tip story. For now, I have trimmed the wing tips to the point where they can be fitted into the wings, aligned, and modified with nut plates for attachment to the wing tips with screws. The final gap will come after the final fitting of the wing tips into the wings.
[Dremel with PVC Cutting Wheel, 40” Straight Edge, Spring Clamps, 1/2" Electrical tape, Sanding Blocks, 120 Grit Sandpaper, Hobby File]

  Jan 22, 2024     24-01 - Wing TIp (Plans) - (1.7 hours) Category: 24 Wing Tips

1/21/24 - 1.0h
1/22/24 – 0.7h
Fitting the wing tips will likely be a stop-and-go step for me – essentially a filler for gaps in my build schedule that won't get finished until much later in the build process. I plan to take the EAA Sportair Workshop “Fiberglass Techniques for RV Aircraft” in the near future to learn about how to work with and finish fiberglass parts on the RV-14A including the wing tips. Until then, there are some things I can do now on the wing tips.

Like every step in the build process, I started with a review of service bulletins, notifications and letters, and revisions and changes in the Service Information and Revisions section on Van's Website. My plans are up to date, and there weren't any changes or safety notices for the wing tips.

The wing tip plans are relatively short at only 4 pages total, but they cover a lot of ground. The plans also leverage Section 5.18 of the plans, which contains several important notes when working with pre-molded fiberglass parts like the wing tips. One note in particular discusses the alignment of the trailing edge of the wing tip with the trailing edge of the elevator, and how the alignment can lead to inconsistent gaps between the aluminum wing and fiberglass wing tip. The note also cautions against allowing the metal edge of the wing to ride up onto a fiberglass edge radius. There should be a 1/8” to 1/16” gap between the metal edge of the wing and the fiberglass edge radius. That gap will get filled in later with some epoxy resin and cotton flox, and then sanded smooth for a seamless transition from aluminum to fiberglass. Section 5 also recommends having some dedicated tools for fiberglass work since the fiberglass is very abrasive and will quickly dull drill bits and cutting blades. Finally, there is a note in Section 5 to “use soft rivets or do not fuly set normal rivets (shop head height approximately 1.2x the hole diameter). Section 5 has lots of important tidbits!

The plans involve a lot of fitting, trimming, and drilling to install the navigation light lens, nutplates for mating with the wing, and aft wing tip rib. The primary difference with this section of the plans is working with plexiglass and fiber glass instead of aluminum. The plans did not specify the type of screw to attach the navigation light lenses, so I'll probably go with the same screw used to attach the wing tip to the wing – AN507-6R6. The instructions to install the wing tip rib into the wing tip were also a bit confusing – the instructions start by attaching the wing tip to the wing, and then inserting the wing tip rib into the aft edge of the wing tip. I'm not sure how that will work with the wing tip attached to the wing, but perhaps it will be clearer when I get to that point.

The plans for this section call out a special tool, a 10 foot ratchet strap, to help snug the wing tip into the wing prior to drilling the mating holes. I have also set aside some drill bits and a counter-sink bit for this section and future fiberglass work. In addition, I acquired a set of drill bits for plexiglass from a former builder, and I decided to buy a nut plate jig and rivet layout fan. Each wing tip takes 44 nutplates, and I think the nut plate jig will really help with the task of locating, aligning, and drilling the holes for the nut plates. The rivet layout fan should come in handy when I layout the rivet pattern for the wing tip rib, and I'm sure it will get more use later in the build.