With the help of Bernie and Mike (many thanks guys), phase one of
the canopy lay-up was completed yesterday … there were a couple of hiccups during
the heat of battle (most all self imposed) which I’ll get to later. But all and
all it turned out OK.
One of the things I was going to do but forgot
to do in advance, was to make plugs for the gap between the canopy arm and the
upper fuselage skin. Because of time constraints, and the schedules of others, did
not do it before the lay-up process began and as a result, there is a low area
in the lay-up that will need to be filled. No big deal just extra work that may
have been avoided.
The plywood top of the finishing crate was used
for the work surface for cutting the glass cloth. The top for this crate has a
paper coating on it and it works well with the rotary cutter to be mentioned
later. To prepare the lid for the job, the 2x4 stiffeners were removed along
with the staples … packaging tape was placed over the rough spots on the
plywood where the row of staples were. I also used tape to cover the edges of
the plywood so the glass cloth would not snag on the edges of the plywood. This
can be seen in some of the photos below.
Preparing the fiberglass cloth prior to cutting
takes a few minutes because the cloth needs to be straightened out so the fiber
weaves run as straight as possible from side to side and up and down. Then
ready to cut the fabric, I would suggest not even considering the use of scissors,
you WILL want to use a rotary cutting wheel for this task so the cloth can be
cut while it is on a flat surface. Just picking the cloth up to get scissors
under it will distort the weave and the shape. Another tip is to use a sharpie
marking pen or ball point pen to gently trace the shape of the pattern onto the
glass cloth. Yes, the sharpie will suck into the fiber and make wide lines but
if you move the pen quickly that can be mitigated. I used both a fine point sharpie
and ball point pen … the ball point pen was harder to use to make marks, but
the lines were thinner.
Glass fabric with the shape of the pattern
traced onto it.
To cut the glass as mentioned, you WILL want to use
a rotary cutter. It cuts the glass like a hot knife through butter without
disturbing the weave. The cutter was not very expensive, think it cost around
$16 at Wallmart aviation supply.
Using the rotary cutter to cut the pattern
traced onto the glass cloth.
Based on a tip from John, a builder in Virginia, I added about 1/4"
to the bottom edge of all the patterns. This will allow for plenty of extra material
to form the bottom of the canopy skirt (this came in handy). After cutting a
pattern piece it should be placed in a pile with the other pieces cut for that
side. So two piles were made one for the left side and one for the right and
paper was placed between each layer so the cloth could me moved around without
picking it up and distorting the pattern or having the ends fray too much. When
picking up the cut pieces if cloth, I placed a metal ruler under it and lifted
so my fingers could get way under it. This keeps the shape of the glass in
tact. If lifting from the edges, it can easily distort and fray.
Moving the cut piece of glass cloth using a
metal ruler to get way under the piece to give it lots of support.
Prior to beginning the lay-up on the canopy
arms, Vaseline was carefully slathered onto areas of the packaging tape where
the lay-up will cover. This was used in lieu of mold release or car wax.
Slathering Vaseline onto tight areas of the packaging
tape using a cotton swab.
Rubbing a thin film of Vaseline onto the
packaging tape.
A mixture of flox was mixed per the plans and
used to fill the upper areas on the canopy frame arms that were cut out to 1/8".
Next the areas receiving the lay-up are to be wetted with the resin. I decided
to tint the resin for this and the first layer black so it will hopefully have
a nicer look from inside the cockpit.
Here is where I made two out of three back to
back to back errors which got the lay-up off to a rocky start. First error – I had
been using fast drying hardener for the previous flox mixtures and forgot to change
over to the slow hardener. So the painted on epoxy began to set too quickly.
Second error, not a biggie just annoying, is I wanted to mask off the area of
the canopy that will become the bridge and didn’t … so it was inadvertently slathered
with the epoxy mixture and will now require lots of sanding to roughen it up
again.
The first lay-up is to be wetted out on the table
and transferred to the airplane wet. A piece of plastic wrap was placed on the
bench so the glass fabric can be wetted out on the plastic film.
Bernie placing the plastic film on the table
that will be used to transfer the wetted out lay-up to the canopy arms.
Mixing up a batch of epoxy (this time with the
slow hardener) that will be tinted black for the first layer of glass fabric.
When wetting out the fabric a stippling action
is preferable to work the epoxy deep into the fibers as opposed to painting the
epoxy on. Taking a brush and cutting the bristles shorter makes for a good
stippling brush. Also body filler squeegees help to spread the epoxy mixture
evenly once the cloth is wetted.
A cut brush works better for stippling the epoxy
resin into the fabric than brushing.
The third error I made was not flipping the first
lay-up layer upside down onto the plastic film. So after it was already wetted
out, that error was quickly realized and another sheet of plastic wrap was used
to cover it. Of course, now the plastic wrap is sticking to the previous piece
and it became a tough chore to separate them and peal back the film that was
placed on the wrong side. This all took time I did not have because the fast hardener
was beginning to kick off big time.
Moving the first layer of the left lay-up to the
airplane with the plastic wrap ON TOP this time.
The positioning of the lay-up would have been
much easer to adjust had the epoxy bellow it not been to kicking off and getting
really tacky.
First lay-up in position on the left side ... time to quickly get to the right side for the fast hardner is getting really tacky.
Once the lay-up was in position, which turned
out to be quite a chore, the plastic film was pealed off and final tweaking was
done with fingers.
Adjusting the position of the right side’s first
lay-up while Bernie stippled the air bubbles out of the fabric.
After the first layer of the five is in position,
all subsequent layers are to be placed onto the first layer dry and wetted out
in place. When working on Pete’s RV-9A we wetted out all the layers prior to
moving them to the airplane and had great results. But I decided to wet out the
layers per the instructions and applied all the subsequent layers dry and
wetted them out in place. If I were to do it over, I think I would try to wet
them out first. So for the bridge in phase two, I will wet out the pieces first
and see how that compares. I think the big issue for me is when stippling the
epoxy into the glass cloth, the area above the canopy arms got sunken and with
the first layer being fast epoxy, it was not possible pull the material taught
again. Had I made plugs for this area like I wanted to … but forgot, this would
not have been an issue.
To add insult to injury, sometime during the
second lay-up layer the pump exploded off the epoxy resin can while pumping …
the spring came out, the pickup went inside the can, and the epoxy resin went everywhere.
Of course, while trying to screw the pump back in place, even more resin poured
out everywhere. Not sure what caused this so I tightened the threads tightly by
hand and it happened a second time. This time I just made the threads snug and
slowly pressed down on the pump. Seemed to work OK for the rest of the session.
That was a pain in the butt and not being in a good mood from the other faux
pas, this event it really set me off.
Bernie spreading out the fourth layer with a squeegee … getting
it ready to wet out with epoxy resin.
After all five layers of the lay-up were in
place, the entire lay-up was covered with peal-ply which is a Dacron fabric used to adorb excess resin and create texture for the epoxy to adhere to if additional layers are to be applied later ... as in the overpaps from the bridge lay-up in phase two.
Sadly, we were all in a hurry to leave at this point to head out for a get
together later in the evening … so forgot to take a photo of the peal ply in
place. Will need to try to remember that prior to continuing.
Many thanks to builders John in Virginia, Bob in
Wisconsin and Nick in Colorado for their good suggestions.
