First Wing Done!

Truth is I have a tiny bit of sanding left to do, but that shouldn't take more than a few minutes. I'm going to post a video summarizing some highlights about building this wing and a possible major piece of rework that I'll decide about after building the other three wings. I'll be starting on the upper left wing pronto. I'll be documenting that build with video, so there probably won't be any posts here for a while.

(By the way, the wing weighs about 21 pounds.)

Wing—Odds and Ends

There are lots of ways to skin a cat. After getting the leading edge wing tip pieces on, I discovered it needed a good bit of fairing. I wasn't sure how to proceed, so thought I would try an epoxy mix. I had oodles of the epoxy left from O'Reilly, so I mixed some West System colloidal silica filler into some of that. The back of the carton says that it's toward the strong/hard-to-sand end of the spectrum (there's only one more that's more difficult-to-sand/stronger). Well, turns out they weren't kidding. My arm almost fell off sanding that stuff.

So, I bought the 410 (last one on the right of the spectrum—easiest to sand). However, I didn't try that. I might try that one later. I ended up using something else I bought at the same time (from West Marine). It's in a caulking tube and is made for fairing. It's by Pettit Paints and is called EZ-Fair. I like it quite well. It's pretty easy to use and much easier to sand.

Some people also use Bondo and other people recommend Super Fil or Evercoat Quantum Filler. So, there are lots of choices. I'll probably try some of the others on the other three wingtips.

By the way, my fiberglass work is awful! I'm sure I'll get better at it the more I do it, though. Thankfully, you can slop more goo on it, do some more sanding, and cover up the first attempt.

This stuff was really hard to sand.

This carton contains the 410. It should be much easier to sand. I'll try it another time.

This stuff worked pretty well. Unfortunately, it's really expensive. Seems like all epoxies are quite expensive.

One end of the tube that will help to form the cutout in the center of the upper wing.

The other end of the tube that forms the center cutout of the upper wing.

Wing Tip Leading Edge

Making the wing tip leading edge was very challenging. The instructions were AWFUL!!! I read the paragraph many times and didn't understand it. Eventually, it began to make sense, but part of it never did become clear. Still, things worked out okay. Also, I have three more tries to perfect things. :)

 I made patterns out of poster board, then drew an outline onto the aluminum, cutting those out with tin snips. They were still a little big and so required a bit more trimming as we went.

Doing a little trimming with the Dremel. The wing tip leading edge pieces will get drilled and riveted to the piece attached to the leading edge you can see here. I cut the leading edge too short, which placed that little extension piece right over the rib. That made the leading edge stick out slightly due to its increased thickness. This is something I will definitetly get right on the other wings.

My friend Mike did a great job bending the wing tip leading edge pieces. I'll have him show me how to do it for the subsequent ones.

For the other wings, I'll have the leading edge longer as I mentioned above, thus keeping the leading edge from being thicker over the last rib (i.e., the piece of aluminum joining the leading edge and wing tip pieces will be outboard of the rib, not over it). Because of that, I don't think I'll need to put that vertical piece of fiber glass there on the other wings (the piece Mike is holding in this photo). I could be wrong, though, and might still want some fiberglass there to smooth things over. We'll see.

To hold the two wing tip leading edge pieces in place while we applied the fiberglass, we began by using some double sided tape under the metal. That didn't hold, so we applied thin strips of gaffer's tape. That was working okay until we clamped down the bottom of those pieces to the spar so they would hold that position while the epoxy cured. Then, the tops (leading edge) of those pieces pulled away a little bit. In a panic, I drilled a couple holes straight through the two pieces and put a couple screws through. After the epoxy cured, I removed the screws, then just put another layer of fiberglass over the first layer which covered up those holes just fine. Not sure what I'll do for the other ones. I'll have to think about it. This one turned out quite good, though.

We bought this fiberglass and epoxy just down the road at O'Reilly Auto Parts.

For some reason, there was space between the wing tip leading edge pieces and the spar, so I made a couple thin strips to take up that space. It turned out very nice. I epoxied them in place, then put nails through the aluminum and wood pieces into the spar. The nails and epoxy would have gone in anyway. I just added the wood filler to get a better shape with the aluminum.

The final fit of the aluminum wing tip leading edge on the spar. Very nice. Just needs a little dusting off.

A flapper disc (sand paper flaps on a wheel) made quick work of the epoxy. I also experimented with using different epoxy mixtures for fairing this area. I'll report on those later. I'm convinced (even though I'm still experimenting) that I would be MUCH better off using some softer materials (epoxies made for fairing) that sand more easily than epoxy mixtures that are so hard I need to use power tools to smooth them out. Also, I'm very inexperienced with composites, so I'm sure there are tricks to use to make this whole thing easier with better results and less work. Still, this first one is looking pretty darn good. Very nice, smooth curves.

Easy does it! Don't want to sand right through the aluminum!!!

Installing the Leading Edge

Installing the leading edge was tough! It took lots of fiddling to get it to fit just right, especially where the brackets poke through on the outboard end, and even then, I cut the openings too big. It'll be covered with fabric, so it doesn't really matter, though. And nailing took a long time. My back was killing me by the time I was done with that.

We scuffed up the areas where there would be contact with epoxy, for better adhesion. I put epoxy along the edges where I would be nailing, but I also epoxied along the very leading edge.

Trimming the end to length.

A view inside the wing with the leading edge on.

The final dry fit. We did probably more than a half dozen dry fits.

I'm applying epoxy here to the leading edge strip, the nail strips on the spar,
the butt rib, and the rib on the far outside.

I had also epoxied the aluminum angle pieces. This piece of spruce applied pressure to that area to keep that aluminum stringer snugly against the nose ribs while the epoxy cured.

My friend, Mike, thought of using this scrap piece of 2x2 to bend over the edges of the leading edge aluminum. You do this simply to remove an area of potentially abrasive contact of sharp metal on the fabric. Notice the straps. I bought these on Amazon pretty cheaply. I put one over each rib to help keep the leading edge tight while I nailed. I don't think I would use the kind with ratchets. You could pretty easily damage the ribs by over-tightening those straps. These worked fine.

Trailing Edge, Wing Tip Bow, and Leading Edge Test Fit

Bending the bits of the trailing edge where they fit over the rear end of each rib.

After doing this, I thought of the idea of making a wedge out of oak to smooth things out a bit. I made the wedge the same shape and size as the rear two inches, or so, of the rib. Then, after this initial bending with the needle nose pliers, we stuck it into that spot, and banged on it with a metal working hammer (any hammer would probably work). It got the shape nice and smooth. It worked well. I'll do the same thing for the other three wings.

Test fit of the leading edge. We did LOTS of test fits before final install.

Turns out I installed the butt rib a little bit out of alignment with the rest of the ribs. Long story short, I'm going to mix up a little flox (epoxy with some cotton mixed in to thicken it up) and put it in the gap, just for some rigidity behind the thin sheet aluminum. The gap is on the right hand side of this photo near the top and is several inches long. I thought that would be better than forcing the aluminum into conformity and causing other deformities in the material. Something to look out for on subsequent wings.

It's really tough to get the whole leading edge sheet down tight to the ribs and other components. I'll talk about that more later one (future blog posts).

This is one of the cutouts for the wing brackets to poke through. I started by drilling out the two ends. Then I tried using tin snips to cut. That did not work at all! I ended up thinking of using my Dremel with a cutoff wheel.

I used this stone wheel to round off some of the corners in the cutouts for the brackets.

The cutoff wheel on the right was one of the ones that came with the Dremel. It's super thin. If it binded at all, it just exploded! I destroyed two of them pretty quickly. I bought a 5-pack of the ones on the left at Home Depot. They're way thicker and stronger. They work great and should last a long time. They working great for cutting the aluminum sheet.

A view of the angle aluminum stringers.

Drilling holes for screws which will hold the wing tip bows to the leading edge spruce.

Pre-screwing the screws into the wing tip bow.

After the initial forming of the outboard end of the trailing edge where it will fit with the wing tip bow, there was left a sharp end at the inner rear edge. That seemed like a perfect spot for a tear to happen, so it occurred to me to use one of my round needle files to take away the sharp corner—kind of a stress riser, I guess.

Here's how it turned out. Very nice!