(Avro
Racing Baby... pg2)
FUSELAGE CONSTRUCTION:
If I was going to get into trouble anywhere it
was here, and I did. My first step was to try
and construct a “square” fuse box
using the two flat side panels (shown in photo
below). |
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Well, just pinning the sides down didn’t
work. Everything began shifting after I took
it off the board to turn it over, and I ended
up with the dreaded "banana fuse." |
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After this disaster I cut apart the two halves,
removed the bracing, and sanded everything down
to get the glue off it. Then I went back to Don’s
book to see what he says about building a solid
and square fuselage.
Don suggests that the section of the fuse where
the wings mount can be seen as the main "box"
of the fuselage, and should be reinforced. This
fuse box helps support the joining of the two sides
and provides torque and twist resistance during
the remaining build. It also helps when flying. |
In
the photo at right I’ve marked off my
fuse box area. I focused on joining the two
fuse sides at this location. Basically, I
used 90 degree bracing and gussets to fix
the formers and cross members.
You can see that at the first, second and
third vertical members, I’ve added gussets
to make sure they do not flex front to back. |
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Don's advises that gussets should be cut so the
grain of the wood parallels the long edge of the
triangle. This takes advantage of the strength of
the grain - something that never occurred to me.
Also, I realize that the size of the gussets I used
might be more appropriate on a P-30 than a peanut,
but as I get more accustom to cutting them this
way I'll make them smaller and lighter!
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also the gussets at top and bottom of the
fuse box. This makes a very stiff structure.
From here I can use triangles to make sure
that the remaining fuse sections are square
while gluing. |
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To the right you can see the squared fuse
structure, ready to have the curved formers
installed on top.
The plan calls for 1/32" sheeting over
the formers behind the cockpit. Not having
any 1/32" sheet, I sanded 1/16"
sheet to half it's thickness, then soaked
it in a water/ammonia bath for over an hour.
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nose planking |
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With
the formers installed, it was time to bend
and glue the sheet wood over them. This turned
out to be another major disaster. I spent
an hour creating paper templates, cutting
the balsa, and pinning it to the formers.
There’s not a whole lot of wood to pin
the top cover to, and as it dried the 1/32"
sheeting stressed and twisted the tail section
of the frame. So I abandoned this approach,
and simply added stringers to the rear of
the fuse.
I used 1/16" planking to cover the top
front of the fuse, which would later be sanded
down to 1/32" thick. |
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THE PROPELLER:
Don’s recommends we
determine the size of the propeller by taking
the square root of the wing area and multiplying
it by 0.8. This value for the Avro 534 is about
6.34 inches, but I went with a 6-inch prop. Don
suggests a pitch to diameter ratio of 1.4 for
scale craft. The remaining equations are based
on these numbers.
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The prop blank - designed and ready to be
carved and sanded. |
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FINISHING THE FRAMEWORK
The image below shows progress so far. Stringers
are now in place on the rear section of the fuse,
and turtle decking sheet is installed around the
cockpit opening. I also used small stringers to
build up the front portion of the cockpit (a departure
from the plan). |
Progress so far |
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I tossed the propeller into my workbag so I could
do a little sanding at lunchtime, when I proceeded
to break it. It was either salvage these blades
or carve a new one - I opted to save these blades
and attach them to a new hub. |
The nose block is 5 cross-grain laminated sheets,
with a 1/16" diameter aluminum tube inserted
as a prop wire guide. A raised rectangular form
was built on the front of the nose block to frame
a “grill,” made later from black screen
door screening.
The cowl got several coats of balsa filler and sanding
sealer. In this picture you can more clearly see
the receiving boxes for the cabane struts. |
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The landing gear struts are 1/32" thick basswood,
per the plan. The front struts each have a .020
music wire reinforcement imbedded in the middle
of a basswood and soft balsa sandwich. The lateral
connector is basswood also.
Wheels are four cross-grained circles of 1/16 balsa.
The two center layers are solid circles, and the
outer layers are rings glued to each side. The inside
diameter of each ring was sanded at an angle before
being glued on. Each wheel was then sanded round,
drilled and fitted with an aluminum bearing. They
were then finished with three coats of sanding sealer. |
The completed framework |
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