|
Martin,
a recently joined PSSA member, has successfully designed,
built and flown his Firebrand and
helpfully
contributes the sequence of events for our benefit.
This was one of those projects which shouldn’t
really have happened, but it did. A trip to the Vintage Glider
meeting in 1993 gave me the first beginnings of an urge to
scratch build a scale subject. Having chosen one and begun
research and drawing, the subject promptly appeared on the
front cover of a model magazine, so I thought dammit.
I resolved to choose a subject which would not have
been popular with modellers, nor particularly easy
either. A
fine Christmas gift of a book caused early interest in the
Blackburn Firebrand TV IV, of which I have vague childhood
recollections at Eastleigh - 1992 1 think.
The Firebrand has been featured as a true disaster
for the Fleet Air Arm in several publications and Aeroplane
Monthly’ were generous in helping me with early research,
and later came their articles in their ‘Tested and Failed’
series. The full size aircraft was begun in 1939 and was
intended to do wonders for the Navy as a single seat
torpedo-strike aircraft. The project went through so many
changes and modifications that it never saw WWII service, but
featured disastrously on several carriers from 1945 onwards.
All kinds of accidents, failures and unexplained crashes
caused a relatively short active service after a whole
wartime of development, and many pilots felt that the
Firebrand was almost unflyable.
Here was a project for my glider. If I could make
this fly, then all kinds of other things would be possible -
at least, this was my thinking.
The full size Firebrand was huge (51’ 3” span)
and I had to settle for 6th scale rather than the 5th
scale which I really wanted. As it was the model would
span over 102 inches with a wing chord of over 20 inches, so I
knew it would be quite a beast. With a radial engine and a
barn-door as a fin/rudder this was surely going to be a bit of
a challenge. It was, but it hasn’t appeared on anybody’s
front cover either.
Existing drawings were few and scanty to say the very
least, though the research was very enjoyable. I am curious
why the Firebrand isn’t featured in the Scale PIans
handbook, as virtually everything else is. Perhaps nobody has
been as determined as me with the subject?
A huge balk of blue foam was built from 100 mm thick
blocks and laborious work began, hacking, sawing and sanding
my way to a fuselage shape, using carefully callipered
dimensions to get the profiles correct. Gradually, the thing
began to look recognisable and a good finish was eventually
achieved using acres of glass-paper and a big lump of time.
The whole thing was taped up in brown parcel tape and coated with
three layers of 120 gm crowsfoot glasscloth and epoxy resin.
The resin didn’t quite do what it was supposed to do (me and
materials...the usual story) and several weeks were needed
to fully cure the fuselage in order to cut out the foam.
This
done, ply reinforcing formers were fashioned and epoxied in
place with carbon fibre and kevlar strapping in high stress
areas to make sure. Spinner and cowling were made in exactly the
same way - the spinner carries the noseweight so it has to be
strong.
Using Kafir plaster (like dental, but much finer and
harder) I sculpted the plug for the teardrop canopy which was
vacuum-formed as one piece. This stage was very time
consuming, but in my view very enjoyable as a process rather
different from other model making activities. The
detailing
on the finished canopy was ‘planted on’ with
‘plasticard’ or styrene sheet. Much later, I sculpted a
pilot using blue foam and Fine Surface Polyfiller, another
technique which I found surprisingly rewarding.
All flying surfaces were built up in
traditional way using balsa, spruce and ply. For the wing I
chose the Eppler 374 profile which I am partial to, though it
has to be regarded as a departure from true scale, and is noticeably
thinner (to a keen eye) than the original. The centre-section
became integral with the fuselage and houses a torpedo
dropping mechanism (as yet untried). The torpedo
carrying skeg is a very useful ‘handle’ when launching -
so what do you hold when a torpedo is attached? I don’t
know.
The wing tips each carry two full-size
servos as the ailerons and flaps are huge and probably apply a
deal of stress on the servo mechanisms. The plug-in panels use
blade and box joiners and they are held in place with tape -
an arrangement I am not happy with and will change one of
these days. The tailplane is huge in all directions and I
used stout pushrods for both elevator and rudder. The
stabiliser/elevator
assembly is bolt-on and it’s pushrod connection exits from
the very end of the fuselage. Ample internal space enables
the rudder linkage to be enclosed beneath the seating.
The paint finishes and markings have
become a favourite activity with my model making, as each
subject gives a separate opportunity to try new ideas. In this
case all paint finishes were hand painted and sprayed,
including all lettering and detailing. Decals and numerals are
a pain in the rump to find and they usually look wrong any
way. Vinyl and acrylic paints were a joy to use - no smell,
quick drying, easily mixed and easily over-painted when errors
are made. Vinyl (humble emulsion paints) adhere well to all
materials used, and are intermixable with acrylics and other
water-based media. They are light in weight and are water
resistant when dry also. I wouldn’t call them waterproof
exactly,
though I wouldn’t recommend leaving any model immersed in
water for long periods, would you? No.
Servos, receiver and battery are as far
inward as possible, yet I still needed nearly 6lbs of lead to
get the balance point about right. The problem here is that
there is no real way of knowing where the centre of gravity
ought to be. But the big shock was the total weight, which was
around l9lbs and giving a wing loading of 27oz. per square
foot - I knew it was getting heavy but this was quite an
unexpected
outcome. A Wessex clubmate, I’ll call him Glyn Fonteneau,
told me, “Don’t worry about the weight, it’s going to be
big enough to work”. So I didn’t worry (honest), and look
what happened. I decided to fly the Firebrand before modelling
the cockpit and pilot as I couldn’t bring myself to add more
weight at this late stage.
|
Blackburn
Firebrand designed and built by Martin Hursthouse |
So nearly two years after I began came the
moment when I would ask Dave Camp to help me throw this
model from a Wessex slope.
It may be worth
saying now that I am not partial to those 50 inch P55 kippers
(aeroplaice?) which are featured in the press, but I started
to think that maybe their owners knew something that I
didn’t. The Firebrand is impossible to handle alone in a
blow and I had to rely on several friends to get the thing
airborne, given the 20 - 25 knot wind.
Anyway, away it went. Without need for a
tweak of the trims and without any sudden unexpected
manoeuvres, all was well. Glyn was vindicated in his
observation after all, and I am sure the sheer bulk of the
Firebrand was an advantage on the day. An occasional loop
and two rolls (not very well executed) and several low passes
and I began to relax — yes it does fly and it flies in
lumbering scale-like fashion, with everything seeming to take
an age and covering huge distances with little noticeable
effort. Only whilst flown closer in to the slope did it become
apparent how fast it was actually moving; the ‘radial
cowling’ seemed to offer little resistance (drag) and there
was relatively little slipstream noise. One stall occurred,
not by intention, and it was quite deep and took a good while
to recover, so I didn’t do that again.
I had been putting off the moment to land,
but the cold wind finally persuaded me to have a go, and it
all went surprisingly well. A large square circuit, followed
by a line up into wind for finals, and just ease on down.
I
needed no flap on that first occasion, though I found out
later that they are hugely effective in culling speed down
when required.
I am well pleased with this model, a real
one-off which has changed my modelling and flying interests
and opened up new possibilities for me. I felt for some
while that I may have to resort to some form of
power to make this type of thing work, but
from a PSS point of view, it has worked satisfactorily and has
opened the way for many other scratch-build projects. Current
project is a Focke-Wulf FW-190 A8 at 1/5 scale - not just any
example, but a very specific and particular subject, but that
is another story.
|
Martin
lends scale to his impressive model.
102"
span and over 19lbs AUW - awesome! |
Model
details:
Span
- 102"
Wing
Area - 1576" sq
All
up weight - 19lbs. approx.
Loading
-
over 27.7oz/sq.ft.
Wing section - E374
<Back>
|
