Wing and Flap Fairings
I fit and drilled my wing
fairings while I had the wings on for their initial fit. I
had a little trouble figuring out what the plans meant by fitting
everything "flush" to the tanks, and had to work through a few other
small issues, but I'll show you here how I figured them all
out. I waited until the wings were on for the final time and
the flaps had been rigged before doing the flaps. I worked a
bit on getting the seam to disappear into the curve of the fuselage,
and I also had a few problems with edge distance and holes drilled
earlier. This all required some considered improvisation, but
everything worked out and I'm very pleased with the results.
spent a lot of time
bending the F-872A forward wing root
fairing. I used a
piece of PVC that had
approximately a 1-½” diameter to get the initial bend, then a lot of
hand bending and twisting
it fit snug to the wing and was parallel.
When I first read the “make sure the fairings
fit flush to the tanks ”
part of the plans, I was confused.
I finally figured out what they were getting at. They wanted me to make it sit flat
on the wing and continue inboard without pitching up or down. Make sure you check this
all the way around
the leading edge, top and bottom.
I found that the tank
bracket got in the way of the top of
the F-872A fairing, and needed to be trimmed down.
mark the 3/16” gap
along the fuselage, I used an old
set a compass so the
distance between the pencil and the point was 3/16”, then ran it along
fuselage with the point touching the fuselage and the pencil marking a
fit the fairing with
the flap in the full up
position. I started
by making the top
lip sit flush on the flap and bending the fairing until the lower
was parallel to the aft edge of the flap.
Then I worked the aft end of the fairing until
it fit snug against the
fuselage. I didn’t
want the seam in the
fairing to continue until the end. I wanted it to disappear
the fuselage. So I
spent some time
working the very aft end of the fairing to remove the seam and match
of the fuselage. I
started by using a
large hammer to remove the seam, making the end of the fairing flat. Then I bent the
gradual curve of the
fuselage into the fairing.
I went to back drill the holes for the top of the
fairing through the F823 skin and F-815B floor rib, some of the holes
work. So I had to
make new ones. The
old ones would not have given me edge
distance everywhere. If
you look real
hard, you can see that the line of rivets isn’t completely evenly
spaced. This was
what I had to do to get the new
holes with edge distance and out of the way of the old holes. The new matched drilled
fuselage may take
care of this issue, but I would still check for edge distance before
through the fairing.
Did That Happen?
don’t know how it happened, but I messed up the flap
fairings. I had measured their location with the wings on,
and the flaps installed. Then I removed everything and
riveted the fairings in place. When I went back to finally
install the flaps, the fairings didn’t match up. First, I
needed to figure out where I went wrong.
The worst case would be that I had messed up drilling the
wings. I rechecked their angle of attack to ensure they were
right on. The next worse case would be that I had mis-rigged
the ailerons. This would be a simple fix, except for the wig
tips. But they were rigged correctly. The only
thing left is that I installed the flap fairings at the wrong
place. So the answer was to move the fairings.
Unfortunately, if I just lowered the fairings to match the top of the
wing, then old holes would show. This was unacceptable, so I
decided to make new fairings that were just a little larger than the
originals. The lower skin of the flaps doesn’t quite lay flat
on the bottom of the fuselage, they miss by a little less than ½
inch. So I decided that while I was at it, I would make the
fairings match up to the bottom of the flaps.
fairings are kind of “U” shaped.
They look a lot like the originals on the top and back side; they are
just a little larger to ensure they cover the holes. It is on
the bottom of the fuselage that they differ greatly. My new
fairings are about 3 inches wide on the bottom, giving me room to rivet
them to the belly on the inside, while the outside sits under the
bottom flap skin.
made the pattern by starting with the old fairings. I added
poster board strips to the top and back until I got the size I needed
to be able to use the holes across the top and cover the old holes in
the back. Then I added poster board to the bottom to get the
size to match to the belly and flap. Once my cardboard
creation fit the top and bottom of the flap, and covered the holes, I
flattened out the old fairing. This gave me a flat template
to cut a new piece of aluminum. I cut and bent the new
aluminum to fit the top and back just like the old fairing, and drilled
it in place. Then I spent a lot of time hand bending the
bottom until I got a good fit to the belly and flap. I
drilled the holes and then trimmed it to final size.
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Flap Fairings to Final
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