Home' Australian Aviation Magazine : March 2011 Contents 75
MARCH 2011 AUSTRALIAN AVIATION
"As far as is practical in a real re situa-
tion, data [would be] collected, the aircraft
would be monitored in that situation,
photographed, videoed... and that all forms
part of the input to the trial about just how
e ective the aircraft is."
"Ultimately, I guess that's what we're re-
ally interested in, is does it put the re out?"
Secondly, if there are no suitable res,
a series of drop tests are to be conducted,
set up over a designated eld using a 'grid'.
is comprises a series of buckets or plastic
containers set out in a speci c grid-like
pattern, with particular spacings. e
aircraft will then y over them at di erent
speeds, heights and wind conditions, drop-
ping a number of di erent re suppressant
liquids, such as foam, retardant or more re-
cently, a super-absorbent polymer referred
to in the eld as 'gel'.
"Again, all of that would be lmed, ana-
lysed," Alder said.
"We're particularly interested in how
the drop pattern works with the particular
vegetation types we have in Australia ... the
leafy, eucalyptus type canopy has di erent
characteristics to what you ... see in North
"So the trials would include some...
planned trial drops on di erent eucalypt
canopies, di erent eucalypt types."
Conditions permitting, evaluation teams
may also light controlled res to test the
580's e ectiveness, or play it safe and take
advantage of the prescribed burning season
which starts towards the end of the bush-
While the physical trials are being
completed, work is also done to look at the
580's operational integration with other
re ghting aircraft around Australia, cou-
pled with a standard economic evaluation
done after the trial process.
Analysis of the $4 million trial is being
undertaken by researchers from the Bush-
re CRC (Cooperative Research Centre).
One of the subjects of the trial is no
stranger to Australian skies, as C-GYXC
Convair 42 was last operated by Pionair
Australia in Australia as VH-PDV before
being acquired by Conair in 2009.
Converting a tried and true airframe
design into a rebomber requires a few
signi cant changes, as Conair project man-
ager and chief pilot Dennis Graham noted
when he discussed the di erences between
a standard 580 and Conair's variant, spe-
cially modi ed by Kelowna Flightcraft.
"If you're standing and looking at the
outside of the airplane, the rst thing you'll
notice is the big tank on the belly, where it's
been converted," he explained.
at belly tank is the central and only
weapon in the CV580's arsenal. Compris-
ing a single reservoir and two full-length
doors, the 580's 'constant ow retardant
delivery system' (CFRDS) tank is capable
of carrying up to 8000 litres of water, foam
or re retardant, with release managed by
the computer controlled 'continuous ow
Before a drop, the pilot (captain) will
select either a manual or one of ve preset
retardant volume releases (divided into
one-eighth, one-sixth, one-quarter, one-
half or a full load drop), while the copilot
( rst o cer) concentrates on ying the
aircraft and managing its systems. Conair
says the CFRDS allows uniform, clean
and gap-free retardant line coverage of the
Instead of being dropped directly onto a
re, the retardant is dropped onto a target
area ahead of a refront, with the aim of
containing the re and allowing enough
time for re ghters on the ground to move
in and suppress the blaze.
Aside from the CFRDS, Conair's 580
externally looks the same as a standard 580,
with the exception of a shorter nose, as the
weather radar has been removed.
Internally however, the 580 is stripped
out of all unnecessary interior kit, such
as seats, ooring and any other passenger
comforts in order to reduce weight and
increase fuel and re retardant capacity.
Despite its size, the large external tank
has only a small e ect on aircraft perform-
ance, mainly slightly reduced airspeed.
"If you want to be scienti c about it,
when it comes to long range cruise speed,
the aircraft's speed is reduced by about
seven-and-a-half per cent," Graham noted.
" e original Convair 580 without the
tank on it, the wing aps came under the
belly...so these airplanes here have got
30 inches or a metre cut o each ap, so
there's two metres less wing ap than there
would be on a regular 580."
is enables the 580 to stall at a lower
airspeed. Graham revealed that the secret
comes from the close proximity between
the tank and aps.
"When you lower the ap, the air cannot
spill o the end of the aps, it provides a
cushion, and it stalls slower, about two or
three knots slower than it used to."
On the ightdeck TCAS is used to aid
in monitoring air tra c given the 580s low
level operations. A complete communica-
tions suite comprising two VHF radios, a
forestry FM radio and satphone ensures the
pilots are kept up-to-date on the situation,
and how to coordinate their attack.
Speed, range and capacity are the Con-
vairs' advantages over the single engine
modi ed aerial ag aircraft widely used in
Australia for aerial re ghting.
" ese airplanes will go to and from the
re in the order of 270kt. I think most of
the single engine airplanes are in the 150 to
160kt range. So you've got almost twice the
capacity, almost twice the speed and so you
can get to the re quicker and when you
do get there, you've got much more load to
surround that re with.
"Technically, you would need less me-
dium tankers than you would single engine
air tankers, because if you need to draw a
line on a re [front] ... you would do it with
one airplane, whereas with a single engine
air tanker, you might need three of them,
and it would take them longer to get there
UTILITARIAN (left) The Convairs' interiors have been stripped of all unnecessary fittings to reduce weight. (right) Conair's captain Andy Walsh and copilot Andy
Robin. (Michael Serenc)
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