Chapter 10 Canard fabrication
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Another mile stone in the
project! In this chapter we build the
first flying surface and get to cut some cores with the
hot-wire.
I’ll start right out by confessing that I cut my first
canard
up
and put it in the trash. I wasn't careless, it just didn't go
well. Often times on this project I’ll
get discouraged or
disappointed in how a part turned out, well maybe
that
happened once or twice... Usually the next morning the
sun comes up, the birds start
chirping and things don’t
look too
bad after all! Well that
wasn’t the case on this
one. I slept on it a few nights, talked
it over with my wife
and
…..tossed it. I have never regretted it. The second
attempt went very well, the canard is straight and true
with no twist and no issues to haunt
me.
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The power supply was found in a friends garage sale, another
friend with a motor rewind business gave me the welder transformer .
I found about 25
VDC worked well for this length
of cut. I used .032 safety wire and had
no problems. I did have a few broken wires
when using the expensive stuff ACS
sells. The saw itself is simple to
make, maintains tension regardless of temperature and you
won’t break a wire if
you forget to remove tension after a cut.. I used a #75 spring
from the depot and a turnbuckle for initial tension.
I would go for a stronger
spring next time but this was adequate.
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Here are some shots of the foam core cutting process, can you see how my wife could have gotten a hair cut doing this?
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Next the
leading edge of each cores are cut off just in front of the spar cap
trough, the aft cores are set up on trailing edge and jigged
straight using string lines and shims to get it
perfect. Aluminum hardpoints for the lift tabs are installed, then the
shear web lay-ups are
installed. These lay-ups go from spar cap
face, over the front edge and back over to the opposite spar cap face (trough).
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Leading edge cores are
microed in place after attaching the lift tabs. I made my own tabs and used
3/16”
2024 T3
al. I wanted them a little beefier than 1/8”. I know 1/8” is more than adequate but if Nat was
concerned that we don’t even
scratch them I figured a little more
material would be in order. Also gives me
a little margin should corrosion ever get started.
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is visible
here also.
Getting all the plies installed without getting
too high is the challenge here.
One tip for
the spar cap glass I learned: Cut a block of wood to use as a squeegee, trace
and cut the airfoil
curvature
onto the bottom of the block and use this to pack the fibers down. Keep using it after peel ply and
again
after the masking paper is removed. At this stage you can check the spar cap
contour and height
against
the foam core. Works very
well.
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Here you
see the bottom skin has been applied, peel ply is put down and wet out using
epoxy
brought
up from underneath if possible.
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Here you see the glass to glass bond area.
Fill & finish using a sanding jig
Use care here
to ensure you have adequate
with the airfoil
cut into it.
area for the glass to glass bond.
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Nav antenna is installed on top
of the glass
And I'm done with dis guy!
then covered with 1 ply of light weight cloth
from the hardware store. Look closely and you
can see the BNC connector just aft of the lift tab.