042 FLYER DECEMBER 2011 ▼Slingsby FireflyFLIGHT TEST

Mark Greenfield of Ultimate High tests the two-seat aerobatic trainer from Yorkshire which has proved its worth with armed forces around the world

Slingsby Firefly

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.

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

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,

the Bulldog, has its own reputation in a not dissimilar way – several QFIs and students jumped out after spins had gone high-rotational, 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

Slingsby FireflyFLIGHT TEST

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DECEMBER 2011 FLYER 43 ▼

044 FLYER DECEMBER 2011 ▼Slingsby FireflyFLIGHT TEST

Well, if you’re going to try an aerobatics trainer…

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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 short-throw 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

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.

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

P1 instruments are all on the right

046 FLYER DECEMBER 2011 ▼Slingsby FireflyFLIGHT TEST

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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, one-lever 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 spinsParachute 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

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 pre-stall 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

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

The Leasing Option

That long wing does nothing for the roll rate

056 FLYER OCTOBER 2011 ▼Slingsby FireflyFLIGHT TEST

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 powerThe 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

■ DIMENSIONSWingspan ...................................................35ft 2in/10.7mLength .............................................................24ft 9in/7.5m Height ................................................................ 7ft 6in/2.3m ■ WEIGHTS & LOADINGSEmpty weight ............................................ 1,720lb/780kgmauw ......................................................... 2,550lb/1,157kg ■ PERFORMANCECruise speed .............................................259kmh/140ktVne .................................................................361kmh/195kt Rate of climb .......................................................1,380fpm Range ............................................................753km/407nm ■ COST from £47,300 ■ ENGINE Lycoming AEIO-540-D4A5 six-cylinder ■ SEATING2 ■ CONTACT DETAILS www.swiftaircraft.com

TECH SPECSlingsby Firefly T67

050 FLYER DECEMBER 2011 ▼Slingsby FireflyFLIGHT TEST

260hp Lycoming delivers quick climb to altitude

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). ■