Firefly Flight Test in FLYER magazine

FLIGHT TEST
Slingsby Firefly
Slingsby Firefly
Mark Greenfield of Ultimate High tests the two-seat aerobatic
trainer from Yorkshire which has proved its worth with armed
forces around the world
S
wift Aviation purchased 21 Slingsby
T67 Firefly earlier this year – and as
we were looking to expand the
Ultimate High aerobatic and general
handling training fleet, I was very interested in
taking a good look at the aeroplane. The T67
M260 aircraft came from Babcock Defence
Services, who owned and maintained these
military trainers on behalf of the RAF.
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042 FLYER DECEMBER 2011
So on a crisp October morning, Mark Davies
kindly brought G-BWXS to Kemble for me to
evaluate. Mark is a competition aerobatic pilot
who has ferried most of the T67 since their
withdrawal from the Defence Elementary Flying
Training School (DEFTS).
As we walked round the pre-flight check, I
marvelled again at how differently one looks at an
aircraft when you are about to go and fly it –
especially when you are going to explore the
edges of the flight envelope. Some people really
don’t like the Firefly. Stories abound regarding its
‘dangerous spin characteristics’ and ten per cent
of the 80 G-Reg airframes have been involved in
fatal crashes. Chief among the Firefly haters must
be the US Government, who infamously scrapped
110 T3, the US version of the T67M260; perhaps
it is the US taxpayer who should be annoyed, at
FLIGHT TEST
Slingsby Firefly
the Bulldog, has its
own reputation in a not
dissimilar way – several QFIs and
students jumped out after spins had gone highrotational, and recovery had not occurred before
bale out height. But having instructed on the
Bulldog for ten years, I consider it a benign
aerobatic platform that will certainly spin if
provoked but which also gives such transparent
messaging, and such straightforward
pre-stall buffet and incipient spin recovery,
that only the most committed mishandling will
provoke ugliness. Was the Firefly going to
prove more recalcitrant?
First impressions are of a comparatively
sleek and aerodynamically efficient machine,
perhaps not surprising given the motor glider
heritage. First designed by René Fournier in the
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the loss of perfectly serviceable airframes to the
tune of $42+million.
Does the aeroplane really have marginal
handling characteristics? It was used extremely
successfully in the UK as an elementary trainer for
all three services in the British military, and a quick
chat to some of the Qualified Flying Instructors
who taught on it immediately tells a very different
story. Meanwhile it is very obvious that its peer,
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DECEMBER 2011 FLYER 43
FLIGHT TEST
Slingsby Firefly
early 1970s as an all-wooden motor glider, it was
not a financial success and development rights
were sold to Slingsby in 1981. They replaced the
wooden structure with composite material and
installed progressively larger engines. Our test
aircraft was the T67M260 (‘M’ being aimed
successfully at the military market), and this along
with the US version (T67M260-T3A) accounted
for the bulk of the 250 aircraft built.
This version has the Textron-Lycoming
AEIO-540 D4A5, which develops 260hp, and the
nose is noticeably longer compared to the earlier
160hp and 200hp versions. Largely conventional
in appearance, with a fixed windscreen and a
sliding bubble canopy, the aeroplane oozes gentle
purposefulness. Noteworthy are the spades on
the inboard edges of the ailerons (nobody I spoke
with seems to know what they do, and the later
production aircraft did not have them) and the
fabric-covered rudder, which (little known fact)
apparently comes in normal and large sizes. The
T67M260 had the large rudder, and it is worth
noting that the US T3A variant, which was
notionally identical except for the addition of
aircon, had the regular rudder. Nobody has
attributed the smaller rudder to effectiveness of
spin recovery, but this has to be another area
where big is most definitely best. The ailerons,
elevators and rudder are all covered in fabric, and
the flaps in Kevlar.
The aircraft was designed for (among other
things) military pilots to prepare for fast jet flying,
with left hand on throttle and right hand on stick.
P1 instruments are all on the right
Even though there is a repeater throttle on the
left-hand cockpit wall (like the Swedish Bulldogs),
it is a very tight fit for anybody who does not have
matchsticks as legs, and so the P1 position is the
right-hand seat. The entire cockpit is designed
around this, with all primary flight instruments on
this side. The fit is comprehensive and the aircraft
is certified for airways flight; the IFR capability was
an essential requirement for its intended role of
generating high sortie rates with minimal weather
interruptions, and the good climb performance
generated by the 260hp engine was intended to
get the student through the clouds and above the
weather, and still be able to carry out the training
sortie. While flight into known icing is prohibited, if
it was forecast but not confirmed they would
punch through the clag regardless.
While there is some storage room behind the
seats, it is clear that this is not a capacious load
carrier; and although the aircraft can easily reach
your vineyard in Provence, you’ll have to abandon
your overnight bag to make room for even a
single case of wine. There’s not a massive amount
of space for the crew either, even if the army
managed to get two grunts in with bone domes
and parachutes for their training sorties. With full
fuel the -260 has around 230kg available for crew
and baggage, which with bone domes, LSJs
(life-saving jackets) and chutes doesn’t leave
much for luggage; civilian use potentially has more
flex. The small control column sprouts from the
front of the seat, somewhat akin to a car’s shortthrow sports gear stick. Maybe I’m increasingly on
the large size of large, but I definitely felt that
thighs had the potential to impede stick
movement, which in an aircraft with aerobatic
aspirations – and the associated full stick
deflection – is clearly not great.
The RAF trainees had aspirations to graduate
to the Hawk; one of the similarities between the
aircraft is the windscreen rail, which was located
exactly at eye level so you have to split your time
looking either over or under the rail. The only nod
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Well, if you’re going to try
an aerobatics trainer…
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044 FLYER DECEMBER 2011
FLIGHT TEST
Slingsby Firefly
to HOTAS (Hands on Throttle and Stick) is an
electric trim for pitch (no rudder trim on these
aircraft) – extremely useful, as long as pilots avoid
the temptation of trying to make small
adjustments in pitch using trim. Interestingly, onelever power-operation was also mandated in
military use, with rpm always at 2,600 and mixture
full rich. While it did nothing for economy, it did
ensure that engines were well looked after, with
pretty much all engines making their TBO plus
200 hours extensions
Stalls and spins
Parachute on (outside the aeroplane) and
strapping into the five-point harness is
straightforward. Start-up is conventional for a
six-cylinder Lycoming and with the engine already
warm we taxied down the grass taxiway for power
checks. Visibility is good on the ground and the
steerable nosewheel with differential braking
available makes ground-handling a doddle,
although residual thrust at idle is certainly
noticeable. Straightforward power and pre-take-off
checks saw us lining up alongside the C182
camera ship for a stream take-off.
Full power from idle gives decent acceleration
compared to most GA types, and very quickly
easing back on the stick had us airborne and
accelerating quickly to the 80kt climb speed. The
aircraft can notionally make 10,000ft in just over
ten minutes; we caught up with the camera ship
at around 1,000ft and I held the Firefly clear as I
The Leasing Option
Swift Aviation is offering a lease option on its
Firefly. This includes a standing charge of £950
per month plus an hourly rate of £38.50 per
engine hour (from tacho reading)
The above rates include insurance, annual
maintenance and 150-hour checks – the
annual and 150-hour maintenance to be
completed at Swift’s facilities or a designated
substitute.
50-hour checks will be the responsibility
of the lease holder; these can be done by
Swift TG Maintenance if required for a fee of
approximately £550 each.
The minimum lease period is six months.
The above prices are exclusive of VAT.
For sale prices see www.swiftaircraft.com/
Firefly-Aircraft/Firefly-Aircraft-For-Sale.aspx
got used to the handling, which was responsive in
all axes and a little lighter in pitch than the Bulldog.
Happy that the aeroplane is straightforward to fly,
we eased into a close echelon starboard for the
photos. The T67 is easy to fly in balance and the
electric trim is really worth its weight in gold when
flying in formation, and I found myself relaxing
into the aeroplane as we flew various orbits while
we chased the gaps in the autumnal clouds. Hand
signals from Ed the snapper had us moving into
various different stations and I was pleased how
easy the Firefly made the formation changes.
With the photo shoot complete, we were free
to go and play, and I broke away into the newly
liberated airspace around Lyneham. First thing to
be looked at was the stall. Once at height, after
allowing the engine to run at an intermediate
power setting to reduce temperatures, we had a
look at the Vs1 stall. With a closed throttle, two
larger pilots and half fuel the aircraft gave very
clear light buffet warnings from 66kt and was fully
stalled at 60kt, with increasing back stick keeping
the nose up and the aircraft mushing down in the
descent with wings level. After nearly 10 seconds
of this, with neutral aileron and rudder, the
aeroplane eventually dropped the right wing. Stall
recovery is rapid without power and pretty much
instantaneous as you would expect with a
powerful engine.
Stalls with power and flap give an earlier and
more pronounced wing drop, while increasing the
back pressure in steep turns and ignoring the
audio and buffet warnings will have the aircraft
flicking to the right. The handling around the stall
regime is confidence-inspiring, with obvious prestall buffet warning which disappears
instantaneously with relaxation of back pressure.
And so to spinning. Do you have to be brave
to spin the T67, foolhardy or just have a death
wish? From people who have spent far more time
in the aeroplane than I, the answer is simply that
you must ensure that you use the correct recovery
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That long wing does nothing for the roll rate
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046 FLYER DECEMBER 2011
FLIGHT TEST
Slingsby Firefly
technique. Notwithstanding the US grounding
their aircraft as a result of ‘spin problems’, of the
three T3 accidents, only one was a result of a spin
(no parachutes = no option), while one was a
forced landing gone wrong and one was a
miscooked Run In And Break.
Having gained a detailed understanding of the
spin recovery technique in the T67M260 –
because we all know that there is no such thing
as a ‘Standard Spin Recovery’, right? – we
calculated the minimum spin entry height as
being Min Abandon Height (Transition level plus
height of ground) plus minimum height to
commence spin recovery (MAH + 2,000ft) plus
300ft per planned turn (900ft), for a min entry
height of 6,400ft. Other literature has a min entry
height of 3,500ft with ‘an extra 1,000 if
inexperienced’; call me a girl’s blouse if you like,
but I’ll always at least start higher!
Incipient spin recovery requires rudders central
and stick neutral, but the elevator neutral position
seems surprisingly far forward; this will normally
get the aeroplane recovered from up to 1½ turns.
The fully-developed spin shows stabilised
autorotation and recovery – opposite rudder,
pause/centralise ailerons, move stick progressively
forward until spin stops, usually within 1½ to 2
turns – is reasonably rapid and more immediate
than the Bulldog although not as crisp as a
dedicated aerobatic platform.
We didn’t explore the aggravated spin modes
– usually resulting from moving the stick forward
prior to having full anti-spin rudder applied, or by
not having ailerons neutral – but the former
DEFTS QFIs on the Ultimate High team are
adamant that these will only occur through
mishandling and are entirely recoverable with the
correct recovery techniques. This is accomplished
by ensuring you have full anti-spin rudder, then
reapplying full back stick before gently moving the
control column forward until the spin stops.
In practice then, the Firefly is entirely
predictable around the stall, gives substantial
notice of bad things about to happen, and is
straightforward to recover, all of which are
desirable characteristics in a basic/standard
aerobatic platform. So once happy with spins and
stalls, it was on to the individual manoeuvres.
Reserves of power
The loop is straightforward and the bubble
canopy makes looking up to clear the airspace
into which we were about to fly very
straightforward. With entry speeds for each
manoeuvre conveniently marked on the canopy,
a firm 4g entry took us smoothly up with a little
less back pressure than required on a Bulldog,
apexing about 750ft above entry height with a
gentle relax to ensure the loop was round and
then squeezing back again on the vertical down
line to pleasingly fly through the slipstream. Not
wishing to prove it a fluke, I moved on to the
barrel roll and used a 45° bank entry to pull up
into a big and lazy roll, which is pretty
straightforward but starts to highlight the limited
effectiveness of the ailerons.
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Here the diagonal spades can be seen just outboard of the flaps
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056 FLYER OCTOBER 2011
FLIGHT TEST
Slingsby Firefly
Ah yes, the roll performance. I’d been warned
that the Firefly has the slowest roll rate in NATO.
Surely it couldn’t be that bad. Actually, it was;
borderline glacial and if Firefly pilots become good
at slow rolls, it is probably because it is extremely
difficult to roll all the way around without substantial
rudder input. Those massive glider wings present a
substantial impediment to rolling, both in the
horizontal and even more so in the vertical.
Inverted performance is reasonable and the
aircraft can run for a good number of minutes
inverted, depending on the fuel state – the
amount of fuel in the ¾ gallon collector tank
depends on the quantity in the whole tank, with
half fuel only half filling the collector tank.
Mercifully, the aircraft will flick reasonably and a
360° roll seemed to go round in less than a
couple of seconds with a wings-level finish
achievable with just a little practice. Certainly
anybody lucky enough to have seen Alan Wade
display the T67M260 at airshows for Babcock will
have seen that a slow roll rate and draggy ailerons
do not make a decent show impossible; however,
Alan spent a lot of time on the aeroplane, and
may have been the exception that proved the rule
around the Firefly being easy to aerobat, but hard
to aerobat well.
The whole issue of managing energy through
aerobatic sequences is made substantially less
challenging with 260 horses driving the aeroplane,
and in fact this version of the Firefly will certainly
fly a 7,000ft base height for loop after loop
without worrying about having to climb for
additional height. At lower levels, it is clear that
decent reserves of power are available and if
anything I found that I was gaining energy through
most manoeuvres without trying terribly hard.
We finished with a powered touch-and-go and
a glide land. Again the Firefly proved pleasant and
uncomplicated in the circuit and is an easy aircraft
to land, especially with the large wing generating
substantial ground effect to cushion the landing. I
expected to be high on the glide approach with
the high aspect ratio wing but was still higher than
I expected, but sideslip will wash the height off
nicely and it was straightforward with a two-stage
roundout to land on the numbers.
So a nice aeroplane, straightforward and easy
enough to fly. How do you go about getting your
hands on one? Swift Aviation has nine former
Babcock aircraft for sale, and before quoting prices
it’s worth highlighting that when they were
acquired by Babcock in 1993 they were
purchased for something like £220,000, or twice
the going rate of an Extra 300. Set in that context,
the prices quoted today don’t seem so bad at
between £64k and £47k.
Are they worth the money? Well, they don’t
have a Fatigue Index like most Bulldogs and so
even if you aerobat aggressively there is no
obvious end of service providing engines and
props get maintained and TBO’d properly.
Being worked very hard by Babcock has certainly
suited them; private owners won’t put anything
like the same hours on them, and making it a
three-lever power operation will generate far
better fuel economy.
It really boils down to the question of what the
owner wants to do; the T67M260 is very much a
jack of all trades without being master of any. It is
pleasant enough to aerobat, without being in any
way outstanding and with a poor roll rate,
although it can operate happily above cloud layers
and get there quickly. It’s a reasonably long-legged
tourer that will make 575nm at 94kt (in an
unlikely 6.1 hours!) and 360nm at 125kt with
reserves but with limited luggage space. It is a
reasonable IFR aircraft and will fly airways but will
need a Mode S transponder and a moving map
GPS. Running costs will be similar to a Bulldog,
with a slightly higher fuel burn. It’s certainly a
better aircraft that its replacement, the Grob Tutor,
which at double the (1996) cost struggles to carry
out the DEFTS training task. Perhaps
unsurprisingly, they are actually best suited to the
role that they were used for in the military, and if
that is what you are after then the T67M260
would be a great purchase, or possibly even more
attractive under the lease terms being offered
(see the box-out on page 56). ■
TECH SPEC
260hp Lycoming delivers quick
climb to altitude
Slingsby Firefly T67
■ DIMENSIONS
Wingspan....................................................35ft 2in/10.7m
Length.............................................................. 24ft 9in/7.5m
Height................................................................. 7ft 6in/2.3m
■ WEIGHTS & LOADINGS
Empty weight............................................. 1,720lb/780kg
mauw.......................................................... 2,550lb/1,157kg
■ PERFORMANCE
Cruise speed..............................................259kmh/140kt
Vne..................................................................361kmh/195kt
Rate of climb........................................................1,380fpm
Range.............................................................753km/407nm
■ COST
from £47,300
■ ENGINE
Lycoming AEIO-540-D4A5 six-cylinder
■ SEATING
2
■ CONTACT DETAILS
www.swiftaircraft.com
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050 FLYER DECEMBER 2011