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Jim’s trials,
tribulations and success in producing this scratch built model
are recorded by him in his blow by blow account.
How
I built my 60” Messerschmitt Bf 109F-4/Trop “Yellow 14”
or
If
only I had planned it properly in the first place!
The Me-109 has
been a long standing favourite of mine, so, when about four
years ago I managed to locate a Jane’s book on the subject I
decided to “have a go” and design my own.
The usual
procedure followed, choose aerofoil section, decide on
span/scale, work out wing area, decide on a suitable wing
loading for chosen section, then armed with the expected
finished decided on a suitable method of construction.
Having drawn the
plan to 60 inch span (without any tweaking of dimensions,)
it became apparent that the fuselage has beautiful rounded
lines,
as I am not the
best of builders, I decided that a veneered foam fuselage
would be ideal - mistake No 1. Because of its contour, the
fuselage was made up of 14 separate foam sections, 7 on each
side, after assembly and sanding, where necessary, the
structure
was veneered with 1/16 balsa using a quick drying Copydex type
of adhesive obtained from a local carpet fitter - mistake No
2.
To accommodate pushrods, servos and receiver a 2 inch
wide x 3 inch deep slot runs through the fuselage - mistake No
3. By now you will have guessed what I have missed out - the
foam should have been built around a box or space frame to
give the whole structure strength especially in the area of
the wing fixing. To help keep the tail end weight to a
minimum, the fin and rudder were built up - why then did I
use ¼ inch sheet balsa for the stabiliser and elevator - when
will I ever learn!! The spinner, which is 4 inches diameter
and laminated from 1/2 inch off-cuts of balsa, houses a 2 inch
diameter 2200 mA nicad which weighs 8oz. - i couldn’t get the
weight any further forward!!
The chosen wing
section was E193 constructed of foam and veneered with 1/16
inch balsa, this particular wing has elliptical tips which had
to be built up. Why did I choose an E193 section? Our local
slope is very good for thermal models, but not for PSS unless
everything is just right, which is not very often. I thought I
would try to build a model with a reasonable wing area and use
a “lifty” section, did it work, thankfully, yes. One
point, when cutting the wings which had a root of 13.5 inches
and tip of 7.2 inches, it was necessary to thread a 6 inch
length of copper fuel pipe over the hot wire, at the tip, to
act as a heat sink, this prevented too much heat on the foam
and reduced shrinkage.
The whole model
was covered with Solartex and sprayed with acrylic car spray
and all decals from Solartrim, the laurels and swords on the
rudder and the logo on the nose were made by John Kliszat, a
member of my local model club, who produces signs and decals
to order (ABC Signs and Decals tel:- 01524 720928). The
colours in Jane’s and the sprayed model were an identical
match - mistake No 4 - I had not read the small print at the
back of the book that stated, “all the colours were an
artists impression and may differ from the real thing”, and
they did - I won’t do that again. It was only when my son
gave me a book called “Bf-109 Aces of North Africa and the
Mediterranean” did I realise what the true colour should
have been! After rubbing down the model was sprayed in BMC
Marina Sandglow - that looks much better.
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Jim
Ellis holds aloft his own design Me-109 F |
All the mistakes
I made only came to light after I had calculated where the
model should balance - the usual problem much too heavy at the
back end. Having initially hoped to have built a model of 4lb
weight and a wing loading of 15oz/sq.ft. it ended up 5¼lb
weight and 21loz/sq.ft. wing loading. This does seem a little
over the top for E193, however, the flight is slow and
reasonably in keeping with scale speed. It must be said, the
model, when built, was around the anticipated weight, it was
the additional ballast required to balance that was
the problem. Over the years there has been an ongoing
“modification” process, a mini superstructure was added
around the wing/fuselage fixing, the wing fixings do not pull
out when the landing is not perfect. Aerosol foam has been
used in areas that needed “beefing up”, especially after
one particular mishap when the fuselage split. One thing that
I have learnt is that foam/balsa veneer/Solartex are
extremely strong in compression (especially after a landing
that a Kamikaze pilot would have been proud of). On the whole
if more thought had been given to the construction at the
start of the project a much lighter, stronger and manoeuvrable
model would have resulted.
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