As I finish up the tail cone (with the required help to set the last few remaining rivets), I decided to start on construction of the wings, so I pulled out the spars from storage, laid them down on the workbench and removed them from the plastic bagging. Upon detailed examination, the spars and anodized coating look great.
There is a small scratch (1/8" wide) in the coating on one of the spars that appears to have been made before the spars were shipped, but after checking with Van's builder support they recommended just smoothing it out and spot priming that area, so I will do that when I spot prime other parts of the spar after drilling.
I also labelled each spar to easily identify the top/bottom and forward/aft sides.
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| Spars (and other wing parts) laid out prior to starting wing construction |
The first part of wing construction involves preparing the spar to accept wing ribs, skins and other attachments. This begins with attaching spar extensions to the ends of each spar, that are held in place with splice plates and rivets. I started by deburring the edges of all 8 splice plates and clecoing them to each spar. Once clecoed, I labeled each plate to easily identify its location for reassembly later.
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| Spar extensions clecoed in place |
Next I prepared the spar extensions and splice plates for priming with Stewart Systems EkoEtch and EkoPrime.
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| Spar extensions and splice plates ready to be cleaned with EkoEtch |
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| Parts drying after being cleaned and etched |
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| Parts drying after priming with Smoke Gray EkoPrime |
While waiting for the primer to cure, I decided to move on and cut the Wing Box J-channel stiffeners to length. I then test fit them in the spar, and found an issue where the short J-channel nested in the long J-channel. The J-channel is supposed to sit 1/16" higher than the spar flange, but after nesting, the short J-channel sat 1/8" above the long J-channel, and a full 3/16" above the spar flange.
This issue is due to the long J-channel tapering in width from 5/8" down to 1/2" along its length, and is a problem because I cannot match drill the holes into the short J-channel as they would lie along the bend in the J-channel. I have reached out to Van's support to see it they can send me replacement J-channels that have a uniform flange width of 5/8", and am awaiting their response....
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| Issue with nested J-channels due to difference in flange width |
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| View of J-channels from outside the spar |
In the meantime, I decided to jump ahead and fabricate the tie-down brackets for the wing spars. As with the tail tie down, I upsized the hole to 5/16" and tapped it with a 3/8-16 tap.
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| Getting ready to upsize the tie down hole to 5/16" and then tap |
I then drilled a 1/8" pilot hole at the required position, and trimmed the tie down brackets to length.
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| Left tie down bracket after fabrication |
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| Right tie down bracket ready to be match-drilled to the spar |
After a call with Van's Builder Support to discuss my nested J-channel issue, we came up with a solution that allows my to use the J-channels that I originally received. Since the J-channel stiffener provides no structural support, and is solely there to add stiffness to the skin, I can work around my issue by just nesting the longer J-channel (with the narrower flange) inside the shorter J-channel instead of the other way as described in the plans.
Funnily enough, I was told that the J-channel with the narrower flange may be stronger that the regular J-channel because the stiffness comes from the curved J in the channel, which would then be slightly larger. I guess it makes sense, so I decided to continue on. As long as I maintain at least 2D edge distance for the holes I should be good.
There is another issue being discussed in the VAF forums surrounding
laser cut parts. As I have several laser cut parts in my wing kit, I will hold back from riveting them in until Van's provides some guidance on how to proceed with these parts. Therefore I decided not to rivet in the spar extensions (as splice plates appear to laser cut), and just clecoed them in place so I could proceed with the rest of the spar preparation in this section.
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| Spar extensions clecoed in from the bottom so that I could proceed with match drilling the J-channels |
Next, after deburring the edges of all the cut J-channels, I worked on each spar flange in turn and clamped a long and short J-channel in place. I nested the J-channels as needed to get a good fit, trying the keep the J-channel flange 1/16" above the spar flange.
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| J-channels clamped in place with several cleco clamps |
I did find that I had to position the narrower flange width of the long J-channels flush with the spar flange to ensure that I had good edge distance for the holes.
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| Nested J-channels. Note the narrower flange of the J-channel on the right that sits lower to ensure good hole edge distance |
I then proceeded to match drill the holes along the aft portion of the flange into the J-channels, starting by drilling every ninth hole, and then splitting the difference until I had all holes drilled. There are three sections on the bottom spar flange that are not supposed to be drilled, and I taped those off beforehand to ensure that they would be skipped.
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| J-channel after first pass of match drilling. Clecos were inserted as holes were drilled |
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| J-channels on one spar flange fully drilled! |
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| Three sets of holes were skipped during match drilling along the bottom spar flanges |
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| As I am constructing both wings at the same time, there are 4 sets of J-channels that need to be match drilled |
As each spar flange was match drilled to the J-channels, I labeled the channels/stiffeners after drilling and put them aside for later use.
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| 8 J-channels fully drilled and ready to be stored for later use in construction of the wings |
Build Hints
- J-channels used as skin stiffeners have no effect on structural strength. If you cannot get the J-channels to nest well, try swapping the nested order and make necessary adjustments to ensure any holes to be drilled into the channels have the required minimum edge distance.
Primer used: ~30g + 3g distilled water
Time Taken: 11.0 hours
Dates: July 6 - July 15 2023
Wing Main Spar Total Time: 11.0 hours
RV-10 Build Total Time: 422.2 hours
Priming Total Time: 44.3 hours (not included in build time totals)
