(Carving Fuselages For Dummies... pg.3)
Step four
Start sanding away! Do it outside and avoid inhaling
the dust or there will be a lot of frustrating
cleaning and coughing. Very little pressure is
needed, and you should ”clean” the
sandpaper often to get rid of larger pieces of
material that might tear the fuselage surface.
The foam can be sanded any which way, but on balsa
you should follow he fibre direction - except
possibly in the first “roughing out”
stage. Be sure to stop using the coarse grade
sandpapers a bit before the final shape is reached.
The deep furrows might otherwise be hard to sand
away without removing too much material.
For an oval or round fuselage where you have to
get rid of a lot of material, start by removing
as much as possible with a knife or a razor blade.
An emery board and/or some popsicle sticks with
different grades of sand paper are very useful
when shaping for example head rests.
If the plan view included cross sections of the
fuselage, you can fashion templates (negative
half former shapes glued to card) to gauge the
amount of shaping needed at several stations.
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Using former templates to check shape.
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Be sure to have the final shape roughed out and
that the fuselage is symmetrical before starting
to sand with the fine grit papers; it’s frustrating
to have an excellent finish on something that would
shame a banana. Been there, done that…
I sometimes stick headrests and other fairings on
when the fuselage starts to take shape so that they
can blend in with the main body. Just remember not
to glue anything across the centre line seam!
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Two rough fuselages. Note the front fuselage former
tack glued to the upper fuselage to facilitate
the shaping of the front end. This ”fire
wall” could be made from 0,4 mm ply or,
as in this case, 0,5 mm hard balsa.
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Step five
When the outside is finished except for a final
touch up, it’s time to separate the two halves.
I start at the front end since the nose block will
cover all gashes in that area. Do it carefully and
use a razorblade to cut away the glue spots where
necessary. If you used one whole block, separate
the two halves using a wide razorblade that tracks
straight along the cut.
Place the fuselage halves on a soft towel or hold
them in your hand during the hollowing. Remove your
watch and rings, or you may inadvertently dent or
rip your creation. Cut using the hollowing-out tool.
I prefer to cut long and rather shallow groves.
Some people (e.g. Aime and Deadman et al.) recommend
the use of a Dremel or similar
tool with a small drum sander. I prefer not to,
since I don’t feel that I have enough control
of the depth and also due to the massive amounts
of dust that method results in.
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Hollowing out the fuselage.
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Hold the fuselage up against a light source to "guesstimate"
how much more you can cut. The foam becomes more
and more pale blue the thinner the section is. If
you feel unsure about how thin the shell actually
is, you can compare the colour to scrap pieces of
foam in different thicknesses, similarly held up
against the light.
Leave a bit more material in the front, along wing
seats, along the centreline and in other high stress
areas. In blue foam I typically end up with less
than 1mm wall thickness, in expanded PS slightly
more. If you feel the need, fine grit sand paper
can be used to remove ridges or bumps.
Step six
Hold the two halves together and push a pin through
both halves to mark where the rear rubber anchor
will be. Glue a small, 5-6 mm sq., piece of very
thin plywood, on the inside of either half at this
location. The reinforcement can be predrilled to
take the size of Al-tube (or bamboo stick) you want
to use. Note that reinforcement must be a cross
ply either from balsa or some other wood if it’s
a foam fuselage. On a balsa fuselage a small piece
of sheet glued cross-wise to the fuselage fibre
direction seems to be enough.
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The reinforcement glued in place. In this case
two pre-drilled pieces of 0.4 mm ply
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Step seven
Spread glue thinly on both sides of the fuselage
edges and hold them together until they stick. Make
sure that the seam is nice and straight. Since the
walls are very thin and thereby soft, it’s
easy to end up with a deformed shape if you press
to hard. Secure with small pieces of masking tape.
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A rough balsa Junkers CL.1 fuselage. With mock-up
motor and paint, this fuselage weighed 0.97 grams.
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