(Carving Fuselages For Dummies... pg.4)
Step eight
Next, tack glue the rough nose block to the front
former and finish the nose block outer contours.
Be extra careful when sanding, as the foam is
softer than the balsa. Pry it off and cut the
nose block key from the former and the foam inside.
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In this Miles M.20 with an inline motor, the
key is a part of the spinner. The front former
is from 0.4 mm ply.
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Finish the nose block and install a propeller axle
bearing. The foam inside the front former can be
hardened by smearing a thin layer of glue on the
walls of the hole. This will make the nose block
key sit a bit better.
Step nine
Finish the fuselage using the finest sand paper
you can find, 1000 or 1200 grit. Press or carefully
score panel lines using a blunt, thin instrument.
Corrugated metal surfaces can be simulated by carefully
pulling a comb across the foam or balsa.
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Parts of the FVM J23 and the Miles M.20. Really
should get them finished now. Note that there
is no cut out where the canopy is supposed to
go on the left fuselage. This is to keep the fuselage
as strong as possible until I’m ready to
mount the canopy.
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Some builders use several layers of diluted aliphatic
glue with sanding in between to obtain a smooth
surface. After a suggestion by fellow here on SFA
I tried smoothing the foam with an iron on low heat,
somewhere between “nylon” and “silk”.
It works but it’s hard not to overdo it and
melt the thin foam away. Ordinary “fine”
woodwork spackle gives a nice smooth surface, but
adds quite a bit of weight even though I sand most
of it away. I haven’t tried other lightweight
spackles. On peanuts or larger models, you could
try tissue, pre-printed or plain. The foam accepts
water-based acrylics, so colour away! Several diluted
layers make it easier to control the weight gain,
compared to one thick layer.
And there it is! If you’re not satisfied,
use your templates and your experience and make
a new one!
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A Junkers F-13 pistachio after having survived
its first flights (and landings…) but still
awaiting some finishing touches.
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Wings an’ stuff
I cut the wings and empennage from 1 to
3 mm hotwire cut sheets. If the sheet is curved
it can be flattened between two sheets of glass
in the oven at 75 degrees Celsius for five minutes.
Let the sheet cool between the glass plates. An
airfoil can be sanded into the wings much the same
way HLG wings are made. Carefully score the aileron
and rudder lines.
The undercamber can be formed by carefully rubbing
or pulling the wing across the rounded edge of a
table or similar. Go lightly, since some extruded
foams are a bit brittle. The friction from rubbing
may heat the material a bit to facilitate the curving,
and I’ve found that it helps to rub with little
pressure but rather franticly. The camber could
probably also be formed using a heat gun and an
airfoil template as described by for example Graham
Smith, but I have yet to try that.
Deadman et al. make the wings even more like the
carved static models from Ye Goode Olde Days: they
first form the wing taper in the foam block and
then cut the wing outline with a marginal of a few
mm. Then they sand in the upper airfoil shape and
the undercamber. This results in a very light wing
that probably keeps the airfoil shape better than
the thin rolled/curved wings I have used. I’ve
now tried that on a Miles M.20 pistachio, and it
looks good.
It’s of course even nicer to build a tissue
covered balsa wing, at least when the original aircraft
were fabric covered. The “pros” however,
employ some airbrush magic on foam or balsa sheet
wings to give the illusion of ribs, spars and fabric,
but that is a story that someone more capable than
I will have to tell…
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A Nieuport-Delage racer in pistachio scale from
a Roger Aime plan. Asymmetrical stab and broken
wings put this model on hold…
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I use balsa for wing struts, but basswood is probably
OK on peanuts. Since the foam is a bit weak, it
might be a good idea to have struts or strut attachments
that break before the foam does. Rounded, very thin
bamboo is excellent for wheel axles and similar.
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An earlier version of the FVM J23. My first “flying”
pistachio. Second version will be better…
I hope.
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In my last two models, I’ve used cutie tip
shafts to make the propeller bearing tube. I heat
whilst twisting it above a candle flame and then
pull to make a tube with a diameter suitable for
the propeller axle (0,4 mm). Since the material
in these shafts seems to be polythene, I’ve
had to use a special plastic primer that comer with
some cyano glues (e.g. Locktite Super Attak)
to fasten it in the nose block. It’s quick
and works well.
Cuts and bruises
I’ve always looked upon the cuts on my hands
after a session of woodworking or modelling with
a bit of pride. They are proof of something actually
having made. The problem is that even though my
wounds heal in a few days, those nicks and cuts
in the balsa or foam do not. I never seem to finish
a fuselage without having irregularities marring
the otherwise smooth surface of especially the foam
models. I recently stumbled onto some kind of extremely
light modelling clay, possibly similar to the Model
Magic discussed on SFA. In Sweden it’s referred
to as light paper clay and sold by a company called
Panduro. With a very small amount of water added
this clay works as an excellent spackle.
Mixing foam dust from the sanding sessions with
a small amount of diluted water based clear acrylic,
also (sometimes) results in a putty that can be
used. However, I’m not too happy with the
sandability and I haven’t found just the right
mixture of ingredients for the putty to give really
good results, so the clay will be my first choice
from now on.
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Two rather quickly made models from foam: DeHavilland
Comet for X-twin rc and Junkers CL.1 with an Aero-X
motor. The DH 88 was too thin walled to support
the strains from banging into the walls and floor.
I have since made a balsa fuselage instead. The
sort-of Junkers was built in a few hours from
expanded PS to see if such a motor-fuselage combination
would work.
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