Today I picked up some flat bar stock from Millard Metals. The Celebrity wings use fittings of various sizes to attach flying wires, landing wires, N struts, and of course to attach the wings to the fuselage. These are made from 1/8″ and 3/16″ 6061-T6 and 3/16″ 2024-T4. I ordered some 6061 tubing from Aircraft Spruce to use as bushing stock. It will take me a while to get all of the brackets cut and drilled, but I did cut at least one of each piece and marked them for the bolt holes. I’ll drill them with small pilot holes, and once they’re all ready I can start drilling the spars for the bolts to attach them. Once those holes are drilled we can start assembling the first wing. I can install the bushings after the wing is assembled, but the holes need to be drilled first.
Went over this morning to see what remaining tasks I could knock out before starting the first wing assembly, and to do some planning and figuring stuff out — like, how I was going to jig up the trailing edge and other stuff for the wings. Stu came in and had a fantastic idea for using the existing steel rails on his workbench to hold the TE flat and perfectly straight, then supporting the front of the ribs with the other rail. It’s a 10′ bench with 12′ rails, so plenty big enough. It’s a significantly different method than that suggested in the plans, but it’s a pretty unique setup. I’m sure a 2×4 shimmed for the correct angle is a lot easier solution for most people than adjustable 12′ long steel square tube rails. I’m just glad he had them built out of square tube and not round.
Next I gave the main and rear spars a once-over to make sure everything was right. It wasn’t. One of the upper wing main spar tip bow supports was off by 1/2″, the result of not having the two spars oriented the same way when I installed those parts. Or, maybe it was something else. Those supports have been a real pain in the rump, and I have a sneaking feeling I’ll run into issues there again. Anyway, the easiest fix was to cut the offending tip support off with a razor saw, put a slight angle cut on the root end, and re-attach it with appropriate splices. Right now part of the re-assembly is drying; I’m hoping to complete the assembly tonight after the epoxy cures.
I got the ten ribs that I have over there trimmed fore and aft, so they’re ready for assembly. I’m planning to start with the lower left wing, just for the sake of simplicity. The lower right wing gets the wing walk. The two upper wings may or may not get fuel tanks, so I’ll do the lower wings first while I work that out. Therefore the lower left is the simplest and a good place to start, I think.
Stu and I discussed building the wingtip bows. He’s got a 48″ square table with a melamine top. It’s big enough to lay our two bows. I’ll wax it thoroughly and use a glue roller for gluing up the lamination strips. This will be good practice for the tail surfaces, which will need to wait until after the wings are done as they’ll need a 4 x 8 work surface. Now I just need to order a glue roller and about 40 or 50 more spring clamps. Given the size of the stabilizer & elevator assembly, more is better… I’m pretty sure there is no such thing as too many clamps.
Work continues on the spars. Over the past few days I’ve put the wingtip bow supports on all but the upper main spars. Hopefully I’ll do those today or tomorrow.
I’ve been looking for the aluminum stock to make all of the wing attachment fittings. I need a mix of 6061-T6 and 2024-T4, in two different thicknesses. The 6061 isn’t too difficult to find, but as yet I haven’t found anyone that has the 2024 in stock. In fact, Wicks is the only place that even claims to carry the size I need, and they’re out of stock. I’m ordering the 6061 and bushing material. Irritatingly enough, the instructions call out the size of tubing used for the bushings but not the material. I’m fairly sure it’s 6061 AL tubing, and fairly sure it doesn’t matter if it’s AL or 4130 steel.
Rear spars built, and tip supports added. Now building the tip supports for the main spars. At some point I need to get some AL stock and see if I can find my box of 4130 tubing to see if I’ve already got bushing material. Then I will need to drill the holes for the attachment and strut/wire fittings before starting wing assembly.
The spars don’t look terribly complex on the plans, but there really is a lot of detail work involved. It’s dragging on longer than I had hoped since it’s a trip over to Stu’s every time I want to get a little work done. I think I may need to take a little more structured approach to this — study the plans, then make a punch list for each trip so I don’t waste time while I’m there trying to figure out the next step.
Last night I did some work to get the parts ready for the wingtip bow supports on the rear spars. I ended up not gluing them on, since I’ve got to think a little more about how I’m going to clamp the pieces together. I did get the stiffeners glued to the rear face of the upper rear spars.
Up until now everything I’ve done with the spars has resulted in parts that were still interchangeable. Main spars are identical and fore/aft symmetrical, so there’s no right or left side. The rear spars are not fore/aft symmetrical, so now I have a left and a right upper rear spar. I had to take just a few minutes extra to make sure everything was properly oriented before attaching those stiffeners, or I could end up with two left or two right spars. Needless to say, there are some extra pencil markings on them…
Happy birthday to me! 🎂 This morning I glued the two lower rear spars up – webs to caps only, and set them aside to cure. That’s all four rear spars now ready for the addition of the plywood blocks for attachment brackets, flying wires, landing wires, and N struts. The cut-off pieces of 1/16 ply will make shims for the lower main spar strut/landing wire attachment points that need to be 1/8″ above the spar caps.
In the afternoon I went back over and glued in the blocks and plywood plates on the root end of the rear spars. There are other blocks and structure to be installed outboard, where the struts and wires attach, but after taking the time to figure out the plans and exactly what needs to be done it was getting too late to glue those bits up. The plans could benefit from an oblique view to better show how things go together, or at least two views of the area… but they’re old and drawn by hand, and there’s only one view. One has to hope there’s a reason that parts of it are built the way it’s shown. The blocks in the kit are oversized and will need to be trimmed, and I want to make sure I have plenty of time to make sure everything is in the right place.
All four main spars substantially built; exceptions are noted below. Two upper rear spars have been started, with plywood web glued to the upper and lower caps – not really caps, but for lack of a better term…
Remaining work: Main spars need to be trimmed to length and dihedral clearance cut made on the lower spars. All holes need to be drilled, bushings fabricated and glued in place. I’ll need to fabricate and glue in shims for the landing wire/N-strut attach brackets on the lower main spars.
During two working sessions today I got most of the assembly of the lower main spars complete. “Most of”, because when it came to laying out the plywood blocks for the landing wire attach points… well, after a while studying the parts and the prints and the spars, none of it makes any sense. The upper wing spars were not exactly straightforward; a few of the parts didn’t match the plans, but the end result looked correct in that the location and final layout of the blocks matches the print, even if the parts making up those blocks are a bit different. I’ll need to spend more time studying the plans for the spars, as well as the plans for the N-struts and landing wires to figure out what needs to be done.
I also ordered a gallon of T-88, hopefully I’ve got enough to last me until it gets here mid-week.
Edit: After looking at print #15 of the plans, things are quite a bit clearer. That drawing shows the flying wire, landing wire, and N-strut attachments, with part of the spars shown. Tomorrow I’ll be able to glue in the blocks for the lower main spars and, hopefully, get them finished. Well… “finished” is a relative term, I suppose. I haven’t started attaching the parts for the wingtip bow support, but I may just hold off on that for the time being.
It’s been a busy week. The two upper main spars are essentially complete. Spar caps, stiffeners, and all of the filler and reinforcing blocks are assembled. The only thing not done are the outboard ends, where the tapered pieces for the wingtip bow attachment need to be assembled. The two lower main spars are under construction now. Both have the caps and web glued, and one has the stiffeners on one side. I’m planning to finish as much as I can today on the main spars, and hopefully get at least one of the rear spars glued up.
It’s been a real joy working in a place where there’s plenty of room to work. The availability of a large number of bar clamps – in addition to the 40 or so spring clamps I have – really helps as well. I took the day off work yesterday and was able to get over there once in the morning to set up a spar, then again in the afternoon to take that one off of the jig and glue up the next one.
Stu is anxious to get enough pieces built to start getting wings assembled so they look like wings — I can’t say I’m not in agreement. I was a little tempted to build a rear spar after the first main so we could assemble one complete wing, but I’m convinced that this way is a lot more efficient. For one thing, after the first spar we’ve both figured out enough ways to make the process better that each spar is taking less time than the one before. Just as an example, my process for getting epoxy into the grooves in the main spar caps has evolved and gotten much more efficient with each spar. It’s almost a shame there aren’t any more to do. On the last couple I would get some glue on the long edge of a popsicle stick and use that to spread it into the groove. After doing a foot or so, I’d slowly follow through with an acid brush with the bristles trimmed down to about 1/4″ or so, to make sure it was evenly distributed and get any excess out of the groove. The result was the cleanest glue joints of all the spars.
I’ve been going through T-88 like crazy. Gluing 9 and 10 foot long pieces of wood uses a lot of epoxy, and I know the laminations for the wingtip bows and tail surfaces will use a lot as well. Given the price increases since the last time I bought glue, I think I’ll just order a gallon.
