Hoo Boy... has it been a long time... Where did I leave off? Bending wingtip bows, that was 145 shop hours ago!
All the wing fittings were hung on a PVC paint rack. I wrapped a cheap pop-up canopy as a spray booth and sprayed the fittings with a 2-part epoxy primer. This was my first time spraying with this specific setup and there was some learning that needed to happen. A few brush touchups were necessary, but all in all it turned out alright, and the next spraying will be better.
The oak cable guides from quite some time earlier were varnished, and while I had varnish mixed I masked off the spars and varnished everywhere that wasn't going to have something glued to it. In the future, I think I would push this step back and varnish everything at once.
The right wing was then assembled, squared up, and the ribs epoxied in place.
I mocked up the drag wires with string and measured each bay to get final lengths for the drag wires.
I forgot to write down the lengths used in the right wing, but in the left wing four of the diagonals measured 49-1/4" and two measured at 50-1/4". The final wires were cut 3/4" longer than this. One end of the drag wires had already been threaded, so they were cut to final lengths and then threaded on the other end.
It's tough to walk through this process again. It's been almost a year since I did the things I'm recounting.
There was some more cutting, drilling, reaming, and fitting that happened. Aileron spars were epoxied in and once dry the aileron was cut free from the wing. Stiffeners were added to the end ribs of the aileron, aileron bay, and root rib. Diagonal braces were added which reinforce the trailing edge of the aileron bay and the root rib.
I ended up finding and buying pre-bent aluminum trailing edge material which saved me a ton of time in trying to fabricate my own. This was cut to length, bent to fit over the ribs, then drilled for a screw top and bottom into each rib with two on each end. 1/4" capstrip fillers were added between ribs of the aileron, the aileron bay, and along the upper surface of the forward spar.
Somewhere in all of this I backed into the trailing edge of rib 13, the last rib of the wing which defines the outer portion of the aileron bay. This is the rib which the wingtip bow supports, but because I hadn't installed the wingtip bow yet the rib cracked. I epoxied it back in place temporarily to await a future, airworthy repair. This also re-established the correct location of rib 13 and allowed me to fit the wingtip bow I wish I had installed earlier.
Fitting the wingtip bow is a fiddly business. The front has to be cut to the correct angle to mate with the leading edge and leaving a little tab for mounting. The cutouts in the spars need to be coped to fit the bow, and simultaneously the trailing edge of the bow has to be flattened and trimmed to sandwich the trailing edge of rib 13. With this done the wingtip bow can be marked for the proper location of the mounting lugs which were then welded in place. I was concerned about the welding because I was a little out of practice and the tubing has a very thin .028" wall. I welded up a little side project to practice and then tackled the attachment lugs. The welding still felt like juggling fish, but the end result turned out well enough.
With the trailing edges and wingtip bow fitted it was time to start varnishing. Everything gets two coats of epoxy varnish. An acid brush makes varnishing in between gussets fairly simple if time-consuming. Applying a coat from one side on everything takes about 4 hours. Once that's dry the wing can be flipped, the other side varnished, and the process repeated for the second coat.
I broke it up a little more than that because I wanted to get the trailing edges and wingtip bow installed ASAP, so I varnished everything that these would interfere with first.
That finishes up the right wing. I mounted it to the ceiling and started in on the left.
This time I left the drag wires and fittings out until the entire wing was assembled and varnished. I managed to crack rib 13 on this wing as well. After consulting with my EAA tech councilor and a couple other A&Ps it was decided that the easiest fix was to build a new rib and replace the broken one. So I pulled out all my jigs and tooled up to build a new left and right of rib 13. Replacing both broken ribs will add about 15-20 hours to the build.
Today saw the last of the varnish applied and the drag wires have been fitted. Tomorrow I'll torque all the bolts down. Both wingtip bows have been primed with epoxy primer and the left bow has been installed. It's nearly time to put this wing up and pull the other down to repair the broken rib.
The last bits of wing hardware I've had to finish up are the pulley guards for the aileron control cables. They are made from two c-shaped strips of steel, welded into a V-shape then drilled and rounded off. Of the first 6 I welded, two were usable. I cut pieces for six more and bent them up. Two were bent on the wrong bend line, junk. The rest bent up alright and with a more mindful fit-up process they turned out great. I also switched to using .035" welding wire instead of the 1/16" wire I had been using. The thinner wire melts so much quicker it takes welding thin material from fish-juggling territory to hand-sewing.
All the wing fittings were hung on a PVC paint rack. I wrapped a cheap pop-up canopy as a spray booth and sprayed the fittings with a 2-part epoxy primer. This was my first time spraying with this specific setup and there was some learning that needed to happen. A few brush touchups were necessary, but all in all it turned out alright, and the next spraying will be better.
The oak cable guides from quite some time earlier were varnished, and while I had varnish mixed I masked off the spars and varnished everywhere that wasn't going to have something glued to it. In the future, I think I would push this step back and varnish everything at once.
The right wing was then assembled, squared up, and the ribs epoxied in place.
I mocked up the drag wires with string and measured each bay to get final lengths for the drag wires. I forgot to write down the lengths used in the right wing, but in the left wing four of the diagonals measured 49-1/4" and two measured at 50-1/4". The final wires were cut 3/4" longer than this. One end of the drag wires had already been threaded, so they were cut to final lengths and then threaded on the other end.
It's tough to walk through this process again. It's been almost a year since I did the things I'm recounting.
There was some more cutting, drilling, reaming, and fitting that happened. Aileron spars were epoxied in and once dry the aileron was cut free from the wing. Stiffeners were added to the end ribs of the aileron, aileron bay, and root rib. Diagonal braces were added which reinforce the trailing edge of the aileron bay and the root rib.
I ended up finding and buying pre-bent aluminum trailing edge material which saved me a ton of time in trying to fabricate my own. This was cut to length, bent to fit over the ribs, then drilled for a screw top and bottom into each rib with two on each end. 1/4" capstrip fillers were added between ribs of the aileron, the aileron bay, and along the upper surface of the forward spar. Somewhere in all of this I backed into the trailing edge of rib 13, the last rib of the wing which defines the outer portion of the aileron bay. This is the rib which the wingtip bow supports, but because I hadn't installed the wingtip bow yet the rib cracked. I epoxied it back in place temporarily to await a future, airworthy repair. This also re-established the correct location of rib 13 and allowed me to fit the wingtip bow I wish I had installed earlier.
I broke it up a little more than that because I wanted to get the trailing edges and wingtip bow installed ASAP, so I varnished everything that these would interfere with first.
That finishes up the right wing. I mounted it to the ceiling and started in on the left.
This time I left the drag wires and fittings out until the entire wing was assembled and varnished. I managed to crack rib 13 on this wing as well. After consulting with my EAA tech councilor and a couple other A&Ps it was decided that the easiest fix was to build a new rib and replace the broken one. So I pulled out all my jigs and tooled up to build a new left and right of rib 13. Replacing both broken ribs will add about 15-20 hours to the build.
Today saw the last of the varnish applied and the drag wires have been fitted. Tomorrow I'll torque all the bolts down. Both wingtip bows have been primed with epoxy primer and the left bow has been installed. It's nearly time to put this wing up and pull the other down to repair the broken rib.
The last bits of wing hardware I've had to finish up are the pulley guards for the aileron control cables. They are made from two c-shaped strips of steel, welded into a V-shape then drilled and rounded off. Of the first 6 I welded, two were usable. I cut pieces for six more and bent them up. Two were bent on the wrong bend line, junk. The rest bent up alright and with a more mindful fit-up process they turned out great. I also switched to using .035" welding wire instead of the 1/16" wire I had been using. The thinner wire melts so much quicker it takes welding thin material from fish-juggling territory to hand-sewing.
Total time: 364.2 hours
A little side project that is related to the Ace build but not part of it is this guy. A third-hand or "welding finger." I made this from the failed bends of the first wingtip bow. It's just two pieces of tubing and a sharpened nail. This was particularly helpful for holding the wingtip bow attach lugs in place for welding.
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