Goldberg "Gas Bird" Construction Project Session #5
By Tommy Gray
Since last time, I have started on the wings. I have the basic wing structures built, but not joined at the dihedral joints yet. There is also a lot of smaller work to do such as bracing, and leading edge sheeting, which is called for on the plans.
There are a few things I want to note here. In the picture above, you can see that there are some small shims under the front and rear spars. These are to raise them off the plans as the wing is undercambered, and in order to get the spars all the way into the slots in the ribs they have to be elevated as little. These shims allow everything to be pressed down tight and then glued. After I had everything in place, and the ribs stuck into the trailing edge slots and down over the spars, I came back and added the 1/8 square top spar. I left it in one piece all the way from root to tip so that I could get everything together. I will come back later, and with my Zona saw, cut the tips loose from the center sections. I did not glue the tip spars in the rear to the center spars. The front spars, however, are one piece all the way.
In the picture below you can see that the tip spars are smaller than the center spars. The plans call for a 3/16" X 3/8" center rear spar and a 1/8"X3/8" tip spar. The ribs were cut for the 1/8"X3/8" spars all the way, but since I wanted to use the larger spars that were on the plans, I opened up the center ribs so that I could get the larger 3/16" thick spars in the slots. You can see the difference in the shot below. This picture shows the joint between the tip and center wing sections. You can also see the shims I used under the spars, in the picture below.
In the kit, the wing trailing edge pieces for the curved tip sections were precut and furnished. In the picture below, you can also see that I have started gluing in the 3/16" sq. leading edge piece. I did not bend it onto the tip just yet, as I wanted the glue to dry first.
Once the glue was dry, I bent the leading edge, and using some thick CA, I tacked it to the tip ribs. The plans did not match the tip pieces furnished in the kit, so I had to decide what to do in order for everything to go together at the last rib (R-8). I decided to trim off the front of the furnished tip piece, and to let the leading edge go all the way to the side of R-8. This allowed the tip piece to butt flush into the leading edge with just a little trimming. This will look better and make it easier for the leading edge sheeting to more easily go all the way to the tip, following the curve of leading edge.
I finished up the framing on the right wing half. The reason I did it first, was that only half of the wing is shown on the plans (the right half). To make a plan for the left half, I took the plans over to my scanner and scanned them into the computer. Using my graphics editing software, I pieced the three pieces of the scan into one, and then printed them out, using a program I use to print plans, called "TilePrint" (which is readily available off the web).
Once I had the two wing halves built and glued together securely, I used the Zona saw and cut the tips away from the centers, in order to prepare for joining. I will jig the tips up the 4 1/2" that the plans call for, and then glue them securely to the centers, and then add the dihedral braces (which I will have to make out of some 1/8" lite plywood, as the kit did not furnish them). I will then glue the centers together with the 1" dihedral on each side the plan calls for. Once I have everything joined and the dihedral set, I will then go back and sheet the leading edge with the 1/16" sheet called for in the plans. I'll show this in the next session.
Below, you can see the tip section cut away from the center in preparation for joining.
That is all for now!
More to come.....Tommy!
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