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Wings
The wing page is a little choppy. It
jumps around a lot because I'm doing a lot of semi-related stuff that
goes in the wing structure but doesn't deserve it's own page.
Barbara shipped my kit via ABF Trucking. I live in base housing at Maxwell AFB, and it's a major pain to get
deliveries of this sort thru the gate. The ABF dock is less than half a mile from the base, so I picked up the
kit at the dock and saved myself the $125 harassment fee. I took the rear seat out of the Suburban and laid the
middle seats down. Put the skin box in first, then slide the spar box in on top. Bungee the doors and pay
the lady at the desk $260. One of their drivers helped me load out, and I was on my way in about 15 minutes.
Very nice folks.
  The
wings are delivered in two boxes. The spars and long pieces of aluminum stock (fuselage longerons, pushrod tubes
and angle brace stock) are packed in a box that is roughly a foot square and 15 ft long. The rest is packed in a
box that's about 1x3x8 ft. The boxes weigh in at about 200 pounds each, and were surprisingly easy to handle,
despite their size. I got busy unpacking and inventorying all the parts and simply forgot to take pictures of the
process - sorry.
Van could probably cut the price of crating the kits in half if he would stand and watch them staple just one crate.
You might as well go get the cuss-jar and keep it close. You'll need it if you want to salvage the lumber that
you paid $60 for.
 It took me about half the day to inventory the parts and get them all put away.
My 60-drawer parts-box is full. In the end, I had one bag of
aileron hardware back-ordered. I made a mental note of it, labeled a drawer for the pieces and forgot it. A
few weeks later, I wondered if Van had a procedure for tracking and shipping back-ordered parts bags, or if I needed to
ping them from time to time. I found the parts in my mailbox the next day - It seems they do have a process.
You have the option of building first one
wing and then the other. Unless you REALLY don't have room to
do them both at the same time, you'll save a little time working the
wings concurrently.
My wing-building does not follow any
reasonable path that I can determine. Waiting for parts to
replace things that I messed up, stalling over "How do I want to do
that?" and splitting time on the RV-8 have made the RV-7 wing a bit
eclectic. The links below will take you thru some of the major
tasks, and we'll clean up the rest here.
Spars
Ribs
Wing Skins
Ailerons
Flaps
 The wings are
off the jig! And I get some floor space back. I made the cradle with wood salvaged from the shipping crates
and 2x4 and plywood scraps I found around the shop. I didn't add casters
because the floor has a *serious* slant and I'd rather it stay where
I put it..
With the wings nose down, you have easy
access to the rear spar assembly. You need to prepare and
assemble the aileron attach brackets and prep and attach the aileron
and flap gap braces.
 Gather
all the parts for the aileron attach brackets and make a pile of
parts for each bracket. Cleco each assembly together and smooth
the edges.
  Ream all the holes that hold each assembly together.
Disassemble and de-burr the holes and edges. Note which holes
must be countersunk and machine accordingly.
 Clean
and prime the parts, then rivet the assemblies together.
  Cleco
and rivet the aileron brackets to the rear spars.
  The
aileron and flap gap braces are next. De-burr the long edges and lightening holes, then cleco and ream the braces
to the wings.
  Take
the braces off and de-burr the holes. Dimple the top flanges of the aileron gap seals and the matching wing skin
trailing edge holes. Do not dimple the flap brace - you'll countersink it later when you mate the flaps.
  Clean
and prime the parts and cleco the braces to the wings. Rivet the flap braces to the rear spars. Some of the
rivets you can reach with a longeron yoke on the squeezer, some you'll have to shoot. This was my first chance to
use my new 3x rivet gun. It drives -4 rivets much easier than the 2x gun.
  Get
an 8-year-old helper and rivet the aileron gap braces to the wings. Rivet the braces to the spars first, then to
the skins.
The major structural assembly of the wing is complete. Now you can work on some of the stuff that goes in the
wing, such as wiring and plumbing runs.
Plumbing the Wing
I changed my mind several times about what I wanted to run where. I drilled big holes high and forward, thinking
I'd run a piece of PVC for conduit. Then I read postings from other builders who had trouble with the conduit
interfering with the aileron linkage, so I drilled smaller holes for bushings low and further aft. One wing got
one big hole, the other got two little holes. (No, I don't remember why. Probably thinking I needed to get
the coax away from the other runs.)
 I
also changed the pitot runs at least once. I ordered a mast and plumbing kit from SafeAir1 for the Dynon pitot
tube. I also considered a Piper-style blade because they incorporate a static port, but couldn't find one that I
was willing to pay the going rate for. My friend Troy McClendon had an Aero-Instruments heated pitot-static tube
that he didn't use on his RV-8, so I carried it home and quit looking.
   Troy
had a Gretz mount, but was missing the backing plate. I called Wayne Gretz, ordered a replacement plate and cut a
hole in the skin to match.
  The mast I got from Troy was chromed, but had several rust spots on it. I tried buffing the chrome off with
limited success. Turns out that a sharp utility knife made it easy to flake the chrome off in chunks. The
ScotchBrite wheel cleaned up the few spots that wouldn't flake off. It will get a coat of VariPrime the next time
I mix a batch.
  The
final pitot installation has two runs of soft aluminum tube from the
pitot mount to the wing root. Slack in the outboard bay gives
enough play to connect to the pitot tube. 90-degree bulkhead
fittings at the root terminate the runs.
  Here
are a few photos of my NAV antenna installations. A simple
quarter-wave groundplane omni on each tip that will feed separate
radios. I should be able to strip NAV, GS and MB signals off of
these. The antenna itself is nothing more than a piece of wire
cut to length and laid inside the fiberglass wingtip. I'll
glass a small plastic tube to the inside of the wingtip and the wire
will slip inside the tube when the tip is mounted. It's about
28 inches from the BNC connector to the outboard, aft-most point of
the wingtip shell - more than enough room for the wire to lay in a
reasonably straight run. I used a piece of Tefzel so it would
show up in the photo. The final product will probably be a
piece of very small music wire (because it's stiffer, smaller,
slicker and I have some that I'd rather use than throw away).
    Here's
how the wire bundle runs thru the right wing. The fat grey wire is the Whelen strobe cable, the bundle of two is
for landing and Nav lights, while the bundle of six is for the TruTrak roll servo. The coax is for the Nav
antenna, mounted in the wingtip. The left wing is similar, except that the TruTrak bundle is replaced by a #12
wire for the pitot heat. The left wing also one more run of
coax - easier to mount it now than fish it thru later. I still haven't decided
whether to put the GRT magnetometer in the wing or somewhere in aft
fuselage behind the baggage compartment.
Aileron Alignment
 Temporarily
mount the ailerons and make the spacers for the hinge and pushrod bolts. Be
sure you have the correct piece of tubing before you go loping chunks
off. I forgot that I had several different lengths of the small
rigid tube and cut up the first piece I found. It turned out to
be the stock for the flap pushrod, and I had to order more.
With the ailerons mounted and the short pushrods connected, bolt the
aileron alignment jig to the bellcrank and adjust the rod end
bearings until the tooling holes line up.
The prints describe a wooden jig with a
slot cut in it that could be used to align the ailerons. My
table saw is in storage, and I wasn't about to freehand a cut that's
supposed to be dead straight for aligning control surfaces. I
would have had to bug somebody else to borrow their tools and make a
mess in their shop. I didn't care for the idea of clamping a
board to the un-even surfaces of the end ribs, either.
If a string is good for checking the alignment of the spar, it ought to do a fair job on the
ailerons. Here's how. Dig thru your hardware and find two AN3-LONG bolts. You'll also need a length
of string. Monofilament fishing line works well. You could also use sewing thread, as long as it will
stretch a little. (I used nylon twine so it would be easy to see in the pictures.) Tie a generous loop in
one end of the string.
 Slip
one of the bolts in the forward tooling hole of the outboard main rib, so that the threads are inside the rib and the
tooling hole bears on the smooth shank of the bolt.
 Stick
the other bolt in the aft tooling hole of the outboard aileron rib.
  Slip
the loop over the head of the forward bolt and run the thread up and over the aft bolt (clockwise in this example, but
the direction is irrelevant). A little tension on the thread will draw the heads of the bolts toward each other,
and the round bolts
will self-center in the round holes.
 Bring
the string back down to the forward bolt, make the turn and go back up to the aft bolt. Tie a loop in the string
just short of the aft bolt and stretch the string to slip the loop over the bolt.
You should have three runs of
string between the bolts. The run without a loop is the reference line. The other two will be out of line
because they run from the edge of one bolt to the center of the other bolt, rather than from edge to edge. Nudge the bolts in or out until
the string just clears the outboard aileron attach bracket.
 Take
a step or two back and sight the position of the string vs. the aft
tooling hole in the main rib. Adjust the length of the steel
pushrod until the reference line is tangent to the aft tooling hole
in the main rib. Note that the string in this picture is
opposite of the others.
Pushrods
   I
cut the large pushrods to length with a rotary tubing cutter. I
suspect that it compressed the ends of the tube slightly, so that the
prepared rod ends would not slip into the tube. I threaded the
end bearings into the machined bushings from the inside, added two
stop nuts to protect the threads and chucked the whole thing in the
drill press. A few minutes with fine emery cloth and a
ScotchBrite pad polished the bushing enough to get a snug fit in the
tube.
  Slip
the machined bushings in the tubes and drill for the blind rivets
that will attach them. I used a long piece of twine with a
scrap of ScotchBrite tied in the middle to scuff the inside of the
tubes. Trade the ScotchBrite for a solvent soaked rag to clean
the surfaces.
 Then
I riveted one bushing into one end of each tube and poured in a
little primer and sloshed it around. Let it dry overnight and
rivet the two remaining bushings in place. Repeat for the
smaller steel pushrods, but use solid AN470AD4-something rivets
rather than blind rivets.
 I
don't have easy access to a lathe, so making fine adjustments to
aileron spacers, bushings and the like required a little thought.
How to shorten the bushings and still end up with a square edge?
I settled on cutting the bushings a smidgen long and using the drill
press and a bit of emery cloth to tune the length.
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