Today I went through more epoxy than I have since gluing the spar caps. After some sanding and test fitting, I pre-glued the wing wall structure and the two plywood skins. Then Stu helped me clamp the edges down, and pinned down any spots that weren’t firmly in place.
As planned, I used some scrap lumber to make clamping bars. I used strips of geodetic material between them and the skins to ensure good pressure and clamped everything together with bar clamps.
With some epoxy left over, I glued the nose spar onto the aileron and did a little more corner blocking on the wingtip bow supports. With all that clamped, pinned, and taped in place it was time for lunch!
This morning I went over to check on the work I did yesterday. The main portion of the walk structure looks good. I still needed to get the extension (front portion) ready for the skin.
The center plywood support is glued to the first false rib, but of course the plywood skin sits between the ribs. That meant I needed to shave about 1/8″ from the top cap of the false rib. I used the razor plane for most of this work but needed to use a file for some of it like the front edge. I cut the cross supports and used them to gauge whether the top of the middle support/rib was level with the other two. In the end I used a DA sander to “fine tune” the high spots until it was all level.
I also wanted to make sure the front and back edges of the thin plywood are fully supported and level with the thicker ply on the rear portion of the walk. I ended up just cutting a couple of support strips to attach to the top of the spar; I use da cutoff scrap of the wing walk for this as it was the perfect thickness. I also cut a couple of pieces of rib capstrip (I’ve got a lot of it left) to glue to the false spar to support the front edge of the walk extension. The plans don’t call for it, but I’ll feel better with a little added structure there.
I can probably remove half of the capstrip on the center one. if it’s not going to provide any strength, there’s no need for the extra weight!
The plans call for using nailing strips and brads to nail down the plywood skins while the glue dries. That’s one way, but I’m thinking another way would be longer clamping strips and long clamps. One strip would hold down the aft end of the main walk and get clamped to the rear spar. One would hold both the forward end of the main walk and the aft end of the extension and get clamped to the main spar. A third would hold down the forward end of the extension… I’m not entirely sure how that one would get clamped, but since it’s 1/8″ plywood it won’t need a lot of clamping force. I’ll find a place, I’m sure.
Today’s session was pretty much all wing walk. I got the notches for the cross pieces all properly fitted using a large file. I got the nose walk supports similarly modified to fit the cross pieces, and cut to fit the spar. Then I glued on all of the long supports as well as the cross braces under the main portion of the wing walk. The front extension portion will have to wait until I figure out exactly how I’m going to deal with the false rib in the center.
Along the way I also glued the top of the root wing rib to the top of the spar. The root rib is angled slightly to accommodate the dihedral, so the wing walk skin will need to be cut in an irregular shape to fit, of course. It has to be; cutting a simple rectangle would be far too easy.
Today I located and temporarily screwed the bearing blocks in, and cut the aileron free from the wing.
With that done, I decided to have another look at the wing walk situation. I don’t know why the support bits were the way they were, but I decided to just get on with making them work. When I look at the plans, especially the oblique view, indicate that the parts may have been cut in an attempt to match a much earlier version of the wing without much of the reinforcement at the main spar root. Anyway… Two of them had the aft end cut well enough to work at the rear spar. The inboard support needed to be trimmed at both ends. All had to be modified to fit the main spar.
In the end I got all three to fit, though I’m not terribly thrilled with the lack of good options for supporting and blocking the ends.
Next up were the notches for the cross braces. Most were too shallow and look to have been cut out with an end mill or router; the corners were rounded. I used a file to square up the corners and deepen the notches to fit the 1/2 x 3/4 pieces.
I figure I’ve got another hour or so of work to get all of the blocking and support in place before mixing epoxy. Probably more; I still haven’t figured out what I’m going to do about the extension of the walk forward of the main spar. If I build it to plans I’ll need to remove or hack up the first false rib. And of course the plywood pieces require significant modification.
On the bright side, the plywood skin for the wing walk curves nicely and won’t be a problem to get glued down. I’d been worried about that, and had visions of needing to make my own laminated piece there, but it’s fine.
Today I went over and flipped the wing right side up, which is pretty easy to do with that nice big curved handle on one end. I cut and glued in the same bracing I did the other day, this time on the top side of the wing. It went pretty quickly.
Tomorrow I’m hoping to get the torque tube bearing blocks screwed in place and cut the aileron free from the wing. We’ll see how that goes.
This morning I woke up early and couldn’t get back to sleep, so I headed over to get a little work done. I glued and clamped the aileron end plates (CW34) in place, along with the corner blocking for them. I also did a little work shaving off some of the excess plywood and corner blocking on the wingtip bow. I’ll probably just have to switch to some low-grit sandpaper to get that job done. I’d really like to get the plywood gussets cut and glued in — oh, wait, there’s more bracing for the wingtip bows to be done…
This afternoon I figured that after 8 hours or so it was safe to move on. I made another trip over and cut and installed the CW40 plywood stiffeners for the aileron and each end of the aileron bay. Then I cut and glued in supports for the wingtip bow. All of this is just the bottom side — since the wing is upside down. I’ll do the top side once I flip the wing back over, which will likely be tomorrow.
Getting two work sessions per day in could really speed things up. I think I’ll try and do more of that. I’m not thrilled with the fact that I seem to be averaging only three days a week working on this — I need to get a fire lit under things, figuratively speaking.
I may be taking too cautious of an approach here, but I really don’t want to have to do a lot of work on the aileron ends like I did on the first one. carefully measured and cut the trailing edge so I could put the CW34 aileron end plates in place. Then, with the CW34s clamped in to make sure the edges lined up with the ends of the aileron spar, I lined up and glued in the pairs of CW35 pieces on each end of the aileron. I have the AL tubing in place to keep everything perfectly aligned.
I’ll probably go back and glue in the CW34s later on tonight. I probably should have just done it this morning. I get a little paranoid about this part of the process, since I’ve had to adjust or re-cut most of the holes for the torque tube.
Getting the CW35 aileron nose ribs located perfectly in the aileron is critical to making sure the aileron is straight and consistent with the other wing. Today I slid the torque tube into place and checked the fit of all the pieces that I can at this point. After making some adjustments to the holes in the CW36 end plates, I glued the three CW35s in place in the middle of the aileron. The next step will require cutting the trailing edge to install the aileron end caps, so I want to make sure the torque tube location is easily and consistently reproducible.
I think at this point I may just bolt the torque tube bearings in place (I have a set of 3D printed temporary pieces) and cut the last piece of AL tubing in half. This will let me work with a much shorter and easier to handle piece of tubing while setting up the ailerons.
On the first wing I built, I had the aileron pretty much finished before realizing that I’d left out a bunch of corner blocking. It was a real PITA to add it in after the fact! So this time I paid more attention. Today I cut and glued in all (I think) of the corner blocking for the parts I have done. MUCH easier this way!!
Today I flipped the wing over and got the lower aileron spar caps glued in. I also glued and clamped the CW36 end plates, and a couple of the CW32 aileron nose ribs.
I also drilled the holes in all of the remaining CW32 parts. I may need to cut a couple more of those; it looks like I’ll come up short for the upper wings. I’ll check the crate to see if they got loose and are hiding somewhere, but it’s not a big deal – I have the plywood to make them.
