Here we go with the next installment.

Building the Lower Wing Halves...

The lower wing starts by building four reinforced ribs, two for each wing. It's pretty clever really. The plywood partial ribs create pockets at the curved cutouts. These pockets hold disks that when eventually glued into the pockets, become the mounting points for the interwing struts. As the manual says, care must be taken to not get epoxy into the pockets. That would make the insertion of the disks more difficult.

Next comes a pretty traditional wing buildup process. The lower wing is built in two identical but mirrored halves. A hardwood spar is secured to the plans and then the ribs are added. The rib tabs keep everything at the right angle and stable on the table. The manual suggests that you dry mount the ribs on the lower section of the spar and then add the top hardwood spar and then glue them all at one time with CA. I think that it would be tough to keep everything true. I went the more traditional way and set all the ribs in for a test fit and then glued them in one at a time using a triangle to make sure they are all perpendicular. When that all dried, I then set in the upper forward spar for a dry test fit. I removed it, laid in thick CA and then set the upper spar back in. I went in smooth and straight!

There are a lot of steps to this plane. This is not a quick build but a very well designed and strong plane will be the result if you take your time. All the best design features are here. Double hardwood fore and aft spars, plenty of shear ribs, even on the aft spar and all the ribs are capped making them I-beams, again, a strengthening feature.

The trailing edge is added as is wood for the aileron hatch and then the sheeting begins. All along the leading edge is sheeted as is the trailing edge. The center is sheeted next. The instructions imply that just two pieces of sheeting will be enough to sheet the center section. That didn't work for me on either half. There was a very thin gap that was too thin to fill with a sheeting strip but too thick to ignore. I used some scrap 1/4in balsa and scored the sheeting, removed the little bit and glued the 1/4 strip in nice and snug.

So just as you get the wing half built, the plans call for you to cut notches in the root ribs! To be honest, the instructions for marking and then cutting the ribs were confusing and so I left that for later. As it turned out, it was a good idea. Once everything has set, the wing half is to be removed and then the top side is to be sheeting and rib caps added. Since I wanted to add a bomb drop, I held off on finishing the top side. Instead I built the other half of the bottom wing stopping at the same point in the instructions.

Joining the Lower Wing Halves...

Now it was clear how and why the root ribs needed to be notched. It was to accommodate the rib joiners. (Even though I read the instructions several times before I started, this just wasn't evident to me and the picture wasn't particularly clear. Maybe it's just me.) So using the joiners as guides, I marked and cut the ribs. Call me odd but I cringed the whole time while I was cutting such important structural members!

Here is where I deviated from the instructions and highly recommend you do the same. The wings are joined with four plywood joiners. One goes along the leading edge and serves as a front bolt plate. Two more are glued to the fore spar as if they were sheer ribs and the last goes along the trailing edge. If I had sheeted both sides of both halves, I first would have had to insert and glue all the joiners into their positions in one wing half. When dry, I would then have had to slide the other wing half onto the joiners and glue it all together. The existence of the sheeting would have made clamping and getting epoxy into all the best places more difficult.

Since I did not have sheeting on the top of both wing halves, I could glue them into both halves at the same time! (Refer to the pictures below.) It was much easier to get plenty of epoxy where it was needed best. So glue was added to the the root ribs and the front bolt plate joiner and then the wings were joined together and clamped. I used a four foot metal straight edge to make sure the spars were dead straight and aligned. I added the other joiners in but without glue just to hold things in place. After the epoxy hardened, I removed the rest of the joiners, glued them up with fresh epoxy and then put them right back in.

Viola! A wing (almost)!

Next, the bomb drop and aileron wires.