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!

Fitting the Angle Aluminum Stringers

Two 1/2" x 1/2" angle aluminum pieces fit into the leading edge of the wing (one on top and one on the bottom) to support the thin leading edge aluminum sheet. They have to be notched out to fit over the nose ribs. I notched them by using the chop saw to remove the bulk of the material, then finishing up with a file. It worked pretty well.

Fitting the first couple notches

Long way to go still.

All the notches are fit.

Great fit! I put a little epoxy here for good measure when fitting the leading edge.

Making the Upper Wing Inner Corner Bow

There is a cut out at the center of the upper wing. It makes some space for the windshield. I've seen the corners made of wood, but the plans for this plane call for aluminum tubing. I imagine you could do it a variety of ways. We just did it according to plans. My friend Mike made the initial bends. There will be some more work to attach them.

He started by using this propane tank, as it looked about the right radius.

Forgot I had this pipe bender. Turned out to work much better.

It's tough to get a smooth curve, but these turned out pretty good.

Varnishing the Wing

My friend Mike helped me apply the first coat of varnish. I applied the second coat the next morning. It made it easier to suspend the wing from the ceiling so we could get at all sides. I'm using Poly Fiber's epoxy varnish.

More Wing Assembly

The leading edge will be nailed to these strips. Also, it will bend down slightly to their rear, so as to eliminate a source of chaffing on the fabric. I attached these the same way I attached all the corner blocks when assembling the wing—with epoxy and my neighbor's pin nailer.

Some folks say to leave a gap here so that the space in the leading edge can breath, I guess to allow moisture to escape. As you can see, I didn't leave space at both ends. I would butt one end up against a rib, so as to provide a little extra strength and leave the other end open. There is one on the top of the spar like this, and one on the bottom. Should provide for a nice current flow. Of course, it might also not make a lick of difference.

Forming the end of the leading edge spruce strip where the wing tip bow will attach. I began by just taking the corners off with a chisel. When I got close, you can see where I pounded a scrap piece of tubing on to see how much further I needed to take it.

Don't pound the scrap tubing on too far! I was barely able to get it back off!!!

After getting very close, I smoothed it out with some sandpaper.

The end result. Almost looks like a factory dowel!

The leading edge spruce strip installed. You can see the rounded end on the left.

You can see the pin nail through the corner block to attach the leading edge spruce strip. The pin nailer made installing the corner blocks very easy and worked quite effectively.

Some of the other corner blocks (note the pin nails) and the strip for attaching the leading edge aluminum sheet.

The outboard brackets, corner blocks, and leading edge attach strip.

After attaching the leading edge spruce strip, I used this block plane to round it over to a contour to match the nose ribs. I finished it off with a little sanding by hand.

A nice, smooth, rounded, nose contour. Of course it will be covered with aluminum sheet, so it probably doesn't need to be perfect, but it wasn't too difficult to get a nice smooth, curved edge to it.

Attaching the Butt Ribs

Since there are brackets on the end of the wing which hold it to the plane, there's no place to glue on the butt rib like the rest of the ribs are glued to the spars. So, you've got to attach it using a couple pieces of plywood. The plans say to use to, but I used three. The rear of the rib will also be attached to an aluminum tube which will form the rear, curved cutout of the upper wing, along with fabric around the rib, and the spruce compression member, so two probably would be just fine.

Brackets that hold the butt rib to the spars.

Gluing the compression member to the butt rib after fitting it and tightening the drag wires in the inboard-most bay.

Gluing a couple cleats to the main spar to which I will attach the plywood brackets which will hold the butt rib to the spars.

Clamping the spruce compression member to the butt rib.

Gluing one of the butt rib attach braces in place.

Painting the Wing Brackets

I had never painted before, so this was a challenge. I have only very limited advice based on a couple mistakes I made.

I put the primer on too heavy and so got some runs. In prepping the brackets for paint (after priming), I then had to sand those runs down so I'd have a good, flat surface for paint. Unfortunately, I sanded through the alodine and primer to bare metal in a couple spots. It turns out that it's very difficult to cover bare metal with paint.

So, first, put the primer on light so you don't get runs. Second, sand very lightly to scuff the primer in preparation for paint. Also, make sure not to put the paint on too heavy and get runs. You can always put some extra coats on if it's not heavy enough.