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Wing Skins
With the wing skeletons hanging on the jig you can start on the wing skins.
  Make
the wing-walk doublers out of 0.032" sheet stock. You'll need a reasonably flat and smooth work surface that you
don't mind drilling into to match-drill the doublers. (I think I used one of the paper-faced shipping crate lids.)
Refer to the prints and instructions and position the doublers under the skins. Clamp the two sheets to your work surface and match-drill the
Doublers to the top inboard wing skins. I wish we lived
closer to my parents. My dad is always a big help.
  When
you finish drilling the doublers, separate them from the skins and clean up the chips and shavings. Cleco the inboard
skins to the main spars, then slip the wing-walk doublers in place and cleco the skins to the ribs and rear spars. Add
the outboard skins.
  (Are
you out of clecos yet?) I bought 300 in my initial tool kit. Now I have 600. Overkill? Probably, but my
assemblies don't wiggle when I lean on them. Ream all the holes.
Pan American Tool has the best price I've found on
clecos.
  Mount
the bottom wing skins in a similar fashion and ream. Use a straight-edge to draw a few lines on the bottom skins that
intersect at the center of the tie-down bracket - you'll use these lines to locate the bracket when the LE skins are clecoed in
place. I couldn't understand this step to save me, and the light didn't come on until about a month after I had WAGed the
hole location with a square and ruler and drilled it. It was close enough that a little sideways pressure on the Unibit
centered it up just fine.
 Take
all the skins off and de-burr the undersides, then put the tops skins back on and start on the leading edge assemblies, then do
the fuel tanks.
Leading Edge Assemblies
Fuel Tanks
When you're finished tinkering with the leading edges, rivet them to the spars. I was able to reach all the LE rib to
spar rivets without any help, but the angles and reach made it difficult and I buggered quite a few rivets in the process.
My 2x rivet gun was a little weak for the task.
If I had it to do over, I would make a monster bucking bar out of a four- or five-pound chunk of steel and drill it in several
places to accept the AN470 cupped rivet set. Bucking the manufactured heads inside the leading edge assemblies and
driving the tails from the main wing bay should produce better results. A helper would probably have made a big
difference, too.
  After
the LE ribs are riveted to the spars, rivet the skin flanges to the spars.
 With
the leading edge assemblies permanently attached, put the tanks back on the spars. I used two
bolts in each Z-bracket and a screw in every other hole around the skins. Re-check the spar to be sure it is straight and
adjust the jack if necessary.
  Cleco
the top inboard and outboard skins to the skeleton. Don't forget to put the wing walk doubler under the inboard skin at
the root.
  I've
read accounts of builders riveting the skins alone. My arms aren't that long. Besides, it's more fun with help.
Alli used the 3-pound mushroom bar from Avery to buck the rivets. It has become the preferred bucking bar. The mass
sets rivets quickly, and the large face makes it easy to keep the tool flat on the work piece.
  If
you have more room to work than I do, you could probably find a way to rivet the skins by yourself. Dillon and his best friend Ross Diggs did a great job bucking rivets for me.
They were good for about an hour - enough to set about half the rivets in the inboard left skin. Alli helped me
finish the top skins.
 If
it's not obvious from the other pictures, I back-riveted the wing skins. I used the long offset driver from Avery.
It worked well enough, but left occasional bite marks on the flanges (probably poor control on my part). After all the
work was done, I learned that Avery also offers a
long-reach double offset spring-loaded set (Part #4653), similar to the short set (#4595) I used on the control surfaces.
I think it would have done a better job of keeping things together and would have prevented some of the bite marks.
   
 Finally,
rivet the top skins to the rear spar. Remember to mark the locations for longer rivets thru the rear spar doublers
 The
leading edges are riveted to the spars and the tanks are temporarily screwed and bolted in place. The top skins are
riveted to the skeletons. It's beginning to look like a wing. This is a good time to make any final changes or
adjustments to the wiring runs you plan for the wings.
 Take
the wings off the jig and drop them in your cradle, leading edge down. This gives you easy access to the aft side of the
main spar for pitot plumbing, bellcrank installation, etc. I'll address these items on the main
Wings page.
Plan all the wiring runs and prepare the routes with either bushings or conduit. I pulled all the wires and tied related
runs into separate bundles with waxed lacing. Plan the pitot plumbing, install the tubing and prepare the mounting
location. Install the aileron bellcranks and roll servo. Install the aileron brackets and aileron- and flap-gap
braces.
When you have all the internal workings prepared, you can close the wings. Some builders have reported waiting until
after the wings are mated to the fuselage before skinning the bottoms.
The instructions say to lay the wings on a table for riveting the bottom skins. I tried, but found it much easier to
rivet the bottom skins with the wing mounted in the cradle.
  For
the bottom skins, I started with the left wing. I laid the wing on a table and clecoed the inboard skin to the rear spar
and used mason's twine to curl the skin away from the ribs so I could reach the rear spar to buck the rivets. I couldn't
reach past the first bay, so I put the wing back in the cradle. Much better.
  I
shot all the rivets in the rear spar and clecoed the skin back to the ribs. I was able to reach thru the inspection
holes and buck all the rivets. Dad shot the few that I couldn't reach.
 Don't
get in too big a hurry to bang all the rivets in the inboard skin. Remember that the outboard skin joins the inboard skin
at the double-row of rivets, so leave the 8th rib un-riveted and cleco the outboard skin in place. My arms are too short
to reach both sides of the rear spar rivets, so Dad shot while I reached thru the inspection holes and bucked.
 If
you're using a Gretz-type pitot tube mount, don't forget to mount it as you rivet the skin in place. Also remember to
adjust the length of the rivets for the added thickness at the spar flange.
 I
was able to reach all the rivets for the first two ribs, then we curled the outboard end of the skin and reached in under it to
buck the rest.
  We
did things a little differently on the right wing. We clecoed the skin to the inboard ribs and started riveting at
the root. It seemed to work a lot better. The process and pictures are much the same, so I won't repeat them.
The wings are closed. Go back to the main Wings page to see how I
attached the flaps.
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