Sig 1/3 Scale Spacewalker Review
Wings
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The wing is a 3-piece structure. These consist of a left and right wing and a center wing section. Each half of the center wing section is built with its corresponding wing half, and then the two center wing sections are joined together. Building this wing is quite a task. Eight pages of the instruction manual are dedicated to this task! Several sub-assemblies shown below have to be built first before you can even lay the plans on the board to start assembling a wing section. Each wing half, including its corresponding center section) is built as a unit and then separated (cut apart). This is accomplished by joining two ribs together where the center section and the wing half meet. 1/16" balsa spacers are glued between the two ribs. This method allows the wing half and center section to be perfectly aligned as you mount the aluminum wing joiners. After the entire wing is finished, the center section and the wing are sawed apart between the two ribs - thus the reason for the spacers.
Two main spars (spruce), two leading edge spars (balsa) and two trailing edge spars (balsa) are used. The ailerons are built as part of the wing and then cut apart.
Building this wing is going to be a challenge due to the size of the chord (which is constant). It would be much easier if I had a building table that I could walk around - unfortunately I do not, so I will have to do some serious stretching!
3/9/2002 - As mentioned, there are many steps in this process. Aligning and gluing all the ribs in quite time consuming - especially trying to eliminate the warps in the ribs. The rib where the two center sections is critical. A plywood jig is provided to assist in gluing the center section rib in place, but eliminating any warp in this rib while trying to maintain the proper angle is quite a task. Have lots of little clamps and T-pins handy!
The wing-joiner assemblies take a lot of time also. Establishing the proper alignment is not too hard, but marking the holes for drilling is somewhat of a challenge since the space in which to work is somewhat cramped - and big hands don't help. However, the instructions are clear and easy to follow in this area so it hasn't been too much of a challenge.
One of the bigger challenges is ensuring that you complete all of the steps. There are many little components and spacers that have to be installed, and ensuring that you do that correctly is critical - be sure to read (and re-read) the instructions carefully and then mark each step when completed. There is no "jumping ahead" in this wing assembly. However, building the other wing half should go a lot quicker once you get the first one completed.
3/30/2002 - Am nearing completion of the FIRST wing half. Man - this is a builder's delight (or nightmare). So far everything has gone fairly well, except gluing on the bottom trailing edge. This is a fairly tedious task, and if not done correctly, can be a source of trouble. The top trailing edge overlaps the back of the ribs by 1/4". After you cut the tabs off the ribs, you then have to sand the back of the ribs and the underside of the top trailing edge to match the contour of the wing. This is so the bottom trailing edge will overlap the top. You then trim the remainder of the top trailing edge off and sand the trailing edge square. The problem is that if you don't sand the sections of the top trailing edge between the ribs to the correct contour you will have a gap between the top and bottom trailing edges. When you squeeze them together, one of both will be bowed. I fixed the spots where this was a problem by gluing some 1/4" x 1/16" balsa strips to the underside of the top trailing edge between the ribs, and then re-sanded. Then glued the bottom trailing edge on as shown on the plans. Lots of clamps (in this case, clothespins work well) and popsicle sticks. See photo below.
4/4/2002 - Finally finished the first wing half (sans the fiberglass wing tip which comes later). Overall, pleased with the outcome. The one "mistake" I made was gluing the shear webs to the back of the main spars between the ribs where the aluminum wing joiners are attached. Because of this I couldn't remove the wing joiners so I could sand flush the inside rib of the outer wing panel (where the wing panel rib meets the center wing section). I had to sand around the joiners which was less than optimal. Overall, the fit between the center section rib and the wing panel rib was ok, but could have been better. I will not make this mistake on the other wing.
I began the construction of the other wing half on 4/2/2002. Progress is substantially quicker on this wing half since I know where everything goes and how they are supposed to fit together. I can also complete multiple steps at once as opposed to going serially through all steps. If I can continue at this pace I should have the second wing half finished in a week or less.
4/29/2002 - I finished the other wing half and the center wing section. There is additional work to be done, but the fuselage has to be completed before the center section can be completed. The second wing half went much faster than the first, which I expected. I also bought more clamps so I could complete several steps simultaneously. The center wing section was fairly easy to construct, but you need a lot of clamps of various sizes - this is very important when you glue the two sections together. It was fairly easy to install the dihedral braces and the shear webs. The biggest job was cutting a slot in the two center ribs right in front of the rear spars to accept the rear dihedral brace. Since the slot has to go all the way through (completely cut the ribs) you need a fairly deep saw (such as a Zona) and a good hobby knife and/or small chisels. With a little work I got a good tight fit. Even though the instructions didn't call for it, I added 1/4" triangle stock to each side of the rib/dihedral brace joint for additional strength. Now on to the tail feathers and then the fuselage!
7/7/2002 - I finished the wing center section today. See the fuselage section for details of installing the wing hold-down dowels and the landing gear blocks. After that was completed and the wing section mounted to the fuselage it was time to finish up by sheeting the bottom section of the wing. This was done using 5/32" balsa for the front section and 3/32" balsa for the rear section.
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