Flying adventure: Aerobatics in a Zlin at Goodwood Aerodrome
PUBLISHED: 11:00 05 October 2018
Sharing Goodwood (formerly RAF Westhampnett) with another aircraft famed for its elegant shape and sonorous engine note, Bob, Tim and Emma go out to play | Words Bob Grimstead and Tim Cooper - Photos: Tim Cooper
I am in love with a Czech ballerina of a ‘certain age’, whose unusual name is Bewo. Although beauty is in the eye of the beholder, few deny she’s the most graceful and I have been holding her close as much as possible lately.
For the youngsters among you who’ve never heard of her and her sisters, in my youth the Zlin-26 family comprised rare, exotic and almost mythical Eastern European beauties. The constant companions of my boyhood heroes Neil Williams, James Black, Neville Browning and Ladislav Bezák, Zlins were graceful, lithe and nimble, clean and strong, and had proper inverted systems.
They were the top competition and display aeroplanes of the 1960s, and I grew up watching them gracefully swing and swoop around the sky.
They flew rings around our Tiger Moths and Chipmunks, and even the flashy imported Franco-Belgian Stampes with their simple, cobbled-together Rollason two-lever fuel injection systems. Zlins introduced to British aerobatics their flabbergasting Czech signature manoeuvre, the lomçovak, and they demonstrated it at every display.
The Zlins’ Walter engines sounded wonderful too. In-line sixes with short, straight exhaust pipes, they chortled on the ground but snarled into the air, sounding for all the world like mini-Merlins. As a teenager, I watched and admired them as they flowed and tumbled through their energetic display routines.
I never even dreamed of flying one−that was way beyond my London suburb ambitions. The most I could hope for then was maybe to have a part share in a simple and inexpensive autogyro. But jump forward fifty years and...
One Monday in June the lovely couple that is Tim and Emma Cooper visited me to discuss another aviation topic. You will know Tim from his excellent Pilot series ‘Under African Skies’.
They mentioned, “We have a Zlin and would like some help to improve our aerobatics. Would you come and fly with us to give us a few tips?”
As you get older making friends becomes less easy, but I knew at first meeting that the Coopers would quickly become firm buddies. With them I am getting to know their aeroplane, and having an absolute ball into the bargain so, whatever the future brings, 2018 will always be ‘the Zlin summer’ for me.
That week I had − and still have − a million things more important to do (including two aeroplanes in urgent need of rebuild), and I’m way behind with my chores and admin, but I have learned that chances like this rarely come around a second time. Also I have vowed never to miss any more great opportunities.
Why we bought a Zlin
When I had an island in Africa and an airstrip all I wanted to do was to fly around inverted – a hangover from schooldays air experience flights in Chipmunks. Back now in the UK, my wife Emma and I knew we needed another aeroplane, but what to buy?
Ideally the aircraft should have the potential to earn its own keep so, erring on the side of safety, it would be an EASA C of A aircraft. It would have to be a taildragger – in 8,000 hours of flying Emma had just a handful of hours in aeroplanes with proper undercarriages.
It had to have a sensible range but only needed two seats. It would have to be able to carry minimal luggage for a few days away, and space for our tiny Ugandan hound, Spinner who loves flying and fits in a small, soft dog carrier.
It would have to be excellent at aerobatics – a machine which would teach us how to fly. Ideally it would be a classic – it would be joining a stable that included a 1930 Riley race car and a Mk 2 Jag. It needed spare parts availability and sensible running costs. It should be reasonably priced.
We started with a long list and it didn’t take a great effort to whittle this down to either a Decathlon or a Zlin. Emma flew both: there was no contest. The Zlin was a little less practical but it could work with optional tip tanks for touring, and spare knickers and a toothbrush stowed in the parachute cut-outs in the seats, with the dog in the luggage space. The clincher for us was the association with the late, great Neil Williams.
If the Zlin were a car then it would be a sixties Ferrari 250 GTO. But you’d pay millions for one of those, whereas a good Zlin, also a proper thoroughbred, won’t set you back more than £60,000. So that is how G-BEWO entered our lives. You may find that you too need a Zlin. Tim Cooper
Regular readers may have seen my single-seat, constant-speed Zlin 326 air test in Pilot September 2009 but, as always with these features, I only got a one-hour flight to assess its qualities. Now I have had a much better chance to become acquainted with its two-seat sister, a beautifully restored and low-hours example of a 326 with a lighter, fixed-pitch wooden propeller.
For the best part of a month I flew four, five and six aerobatic sorties per day in beautiful summer weather with temperatures in the upper twenties and low thirties. The whole affair had serious echoes of the Battle of Britain. Streams of high, glistening contrails criss-crossing the wide blue vault above us, crispy browned grass beneath our feet, salt-encrusted flying overalls, silk scarf, sweat-slippery gloves, trussed-up in parachutes, in a tailwheel aeroplane and that six cylinder in-line engine, plus a trio of joy-flying Boultbee Spitfires coming and going in clouds of propwash dust.
In some ways it’s been like that movie Groundhog Day. I got up when I woke up, showered, dressed, made a sandwich, filled a water bottle and dashed out of the door. We flew all day until we were out of either fuel or daylight (or both), and stumbled home, scoffed whatever was left in the fridge, showered away the salt and tumbled into bed.
One day I didn’t get back until nearly 11 p.m., but ask me if I complained! To date we’ve flown nearly thirty sorties, although both Tim and I have had to take a couple of days out (despite the ongoing frustratingly glorious weather) to write Pilot articles.
Obviously, stalls and spins came first, and we also explored tail slides and other recoveries from botched manoeuvres... initially deliberately, but later probably not so much.
The aerobatics proper started with simple loops and ballistic aileron rolls, before progressing to the slow (axial) and barrel varieties. Then we could start joining up these manoeuvres to make combination figures like quarter clovers, half-Cubans and half reverse-Cubans.
Stall turns followed−to the right of course: this is a European engine−followed by exploring and extending the vertical up line for humpty-bumps (tight radius, canopy-down pull-overs) and quarter vertical rolls. The Walter engine’s dual-carburettor inverted fuel system helps here, warning you with its famous ‘Zlin cough’ the moment you go beyond vertical.
Next, I became adventurous and experimented with combining half vertical rolls and push-humpties, and half, three-quarter and full flick-rolls, before going on to avalanches (a tight loop with a full positive flick-roll on the top) and my favourite figure (extremely difficult in my usual Fournier RF4D) the quarter vertical roll, stall turn, three-quarter-flick triplet.
Then it was time to explore sustained inverted flight (this aeroplane’s forté) and knife-edges, which I found very tricky. Bewo’s long control column is great for reducing stick loads at normal speeds and allows great precision, but it does move around the cockpit a lot, and it needs to go a long way forwards when you’re upside-down.
At first I found myself grasping the big round aluminium ball on its top because, with my fingers around the normal handgrip, I just couldn’t push it quite far enough forward, but an extra lumbar cushion soon solved that problem. I also initially found it hard to keep the nose up in knife-edged flight, but a higher entry speed helped here.
The Zlin 326 is an intriguing aeroplane. Built at a similar time, to similar specifications, and with similar configuration and power to our familiar DHC¬1 Chipmunk, it nevertheless has many differences.
The Zlin¬26 family was obviously designed as elementary/primary/basic trainers, but the Czech aerobatic aces soon realised that certain characteristics made them capable of so much more.
The fuel and oil systems permitting four minutes of inverted flight, the swept¬back leading edges and their beneficial effect on flick¬rolling, its clean lines and drag¬reducing retractable main undercarriage legs and consequent increase in vertical climb performance, the gyroscopic effect of that long fuselage nose with its propeller set well forward, plus the airframe’s inherent strength, all combine to give Zlins remarkable aerobatic versatility.
I found it most interesting that, if you fly the Zlin like a Chippie, keeping the airspeed below about 110 knots (200kph) and the g loads within +4/¬2 then its handling, capability and control forces are not too dissimilar (although the much bigger rudder is heavier and does need constant attention).
It is only when you start diving to gain speed and pulling serious g for some of the more adventurous manoeuvres that the aeroplane’s character almost transforms. The controls become heavy in all three axes, so flying a six¬minute sequence can have the same muscular effect as an hour¬long gym workout.
While Zlins have an airframe life of 3,000 hours at the usual +6/¬3g limits, increased limits of +8/¬4.5g were permissible but with a greatly reduced 100¬hour airframe life.
Clearly this is what the Czechs did when they flew their Zlins in international unlimited competitions (there were more than forty of them at the 1970 Hullavington WAC) and presumably that is why the sixties pilots complained of heavy control forces, smacking the controls into all corners of the cockpit with vigour and violence, sorely abusing this graceful aeroplane in pursuit of the square corners suggested by the Aresti notation.
For the sort of aerobatics described here, we haven’t exceeded +5g and ¬2g. You just don’t need to. This aeroplane simply does what you ask of it, provided you ask nicely.
Like many, I regard the Chipmunk’s light and well¬harmonised controls as among the best. The Zlin’s controls are definitely heavier, and much heavier at higher speeds (the reason for those then¬innovative spades) although their harmony is nearly spot¬on and their effectiveness is amazing.
The Zlin’s huge and very capable rudder has no aerodynamic assistance, so I used full left rudder trim in the climb and needed to ensure it was re¬set to neutral before starting aerobatics. Bezák wasn’t joking when he said, “Zlin is rudder airplane. You fly Zlin by rudder.”
Even more so than in a Tiger Moth or Spitfire, you need to get your rudder inputs just right, and all the time – varying them with every change in airspeed and power. The big difference is the Zlin’s pedal forces, which are significantly higher.
I was also surprised to find the Zlin’s spin different from that of the Chipmunks, Stampes and Fourniers to which I am more accustomed. In recovery the Zlin’s rudder and elevator forces are really quite heavy, and it seemed to me to behave more ponderously, like a more massive aeroplane – in the erect spin at least.
Mindful of the handbook’s cautions about keeping the tick¬over rpm below 600, ensuring the throttle is closed, being prepared to kill the engine by switching off the magnetos, and not exceeding three turns, we limited our initial explorations to just two turns each way, but recovery was completely predictable within approximately half a turn. More experimentation will come later.
As with all aeroplanes, if you don’t want to lose height during aerobatics you need to keep the Zlin’s airspeed below its maximum full¬throttle level speed – two¬up at 4,500 feet this was around 195kph. Doing so limits the control forces in all axes to reasonable levels but restricts you to standard level manoeuvres.
Luckily this Zlin’s propeller is well matched to its airspeed band, so max rpm are not reached until 230kph. This means you can leave the throttle wide open (giving approximately 80 per cent power at 4,500 feet) provided you control the airspeed. In turn, that removes one of the three rudder variables, so you need only to coordinate with aileron inputs and airspeed changes.
Inevitably, for the longer vertical lines you need an initial speed¬building dive, with attendant throttle and rudder juggling, but well before you’re going straight up you can open the throttle again.
As with the Fournier family, I’ve found you need increasing forward stick as you climb (if anybody can explain the aerodynamic theory I’d be interested) but otherwise the length of the vertical line seems only to depend on your entry airspeed. I loved flying half¬up roll, half¬down roll push¬humpties in this aeroplane, although you really do need lots of rudder if you leave the power on over the top.
Later 526F versions have 160hp and that magic Avia constant¬speed propeller, so solo, with a Vne dive, they can accomplish a full 360¬degree upward vertical roll, but I’m not even going to attempt one two¬up with just 140hp and a fixed¬pitch prop.
I can only find two areas where caution is needed. The aforementioned spin behaviour may be one, although that’s no practical problem because a) competition spins never require more than two turns and b) if you fly it sympathetically you’ll never get into an unintentional one.
The other is the Zlin’s very clean airframe. Like an Extra or Fournier (or their Slingsby progeny), but unlike all those biplanes out there, it does accelerate spectacularly when going downhill. The tricks are: always start with the nose higher than you think it should be, and keep pulling whenever it’s below the horizon. Those long wings cause such little induced drag that you don’t lose energy, and that low drag makes vertical figures a doddle.
I can only reiterate the advice of every other aviation journalist who’s sampled one. If you ever get the chance to fly a Zlin, don’t hesitate. You won’t regret it.
Tim did count-time my first super-slow roll at twenty seconds−although I suspect it was probably really nearer fifteen−so I was eventually getting the hang of flying along sideways.
One day we flew six sorties for more than three hours of flying, and I felt a bit second-hand afterwards. And of course it took a while to flush out the adrenalin from my system with beer. But it was a wonderful laughternoon.
I haven’t flown only with the Coopers. They have generously shared their aeroplane with friends. One was the local aerobatic ace who was more familiar with modern Zlins; another capable companion was BA 747-400 colleague Chris, who demonstrated his skilful repertoire while I just relaxed and admired his flying.
Then there was his seventeen-year-old daughter, whom I took for her first ever aerobatic flight. She didn’t say very much during the briefing, although she intimated a keenness to do quite a lot.
I always insist that just one or two manoeuvres are quite enough for a first aeros flight, but Becs was in the early stages of her PPL syllabus and said she wanted more. After starting gently with an aileron roll and a 3.5g loop, in the end we flew two of every manoeuvre I could accomplish in the aeroplane so far!
This ended up as half-an-hour of her whooping and laughing with delight through everything I could do, including avalanches, half upward vertical rolls with canopy-up humpty-bumps and fifteen seconds of inverted straight-and-level flight.
She just couldn’t get enough. It was one of those unforgettably delightful flights. I even got a huge hug afterwards. I’m certain we have another aerobatic pilot in the making.
I have been a bit like that young supply teacher we’ve all encountered, only reading up tomorrow’s lesson in Rob Dorsey’s notes and Alan Cassidy’s book the night before – although I think I have managed to stay ahead of the game so far. Furthermore, I have improved both my repertoire and my technique, thanks to the Zlin’s inverted systems and remarkable capabilities.
Because we were going all the way up to 4,500 feet before starting, there was the ever-present problem of getting down again expeditiously without shock-cooling the engine. After our aerobatic workouts, for the first descending 2,000 feet I was happy to loop, barrel-roll and quarter-clover our way downwards at half throttle, but below that a simple speed increase seemed the best way to scrub off height efficiently.
Having witnessed my half-power aerobatics, Emma pronounced herself impressed. Never one to miss the chance of showing off to a beautiful woman, and as a habitual motor-glider pilot, I said, “Oh, well of course you can easily fly aeros without any power at all. Look, I’ll show you.”
Oh dear! I am definitely old enough and wise enough to know that those words (or any similar phrase) said anywhere near an aircraft should ring loud and jangling alarm bells; but I couldn’t hear myself for the rush of blood in my ears!
So I completely closed the throttle, dived to 230kph and pulled firmly and steadily into a loop. All went well until we approached the inverted, by which time the roaring slipstream had dwindled to a sigh and the controls had become slack in my hands.
I knew I was in real trouble when the propeller disc morphed into individual blades flicking past. Then there was silence and a single blade sticking up ahead in mocking admonition.
As I struggled with unresisting, unresponsive controls to regain a sensible attitude, a little airspeed and the merest smidgen of self-respect, my headphones rang with the melody of Emma’s laughter.
So OK, I now know that a) it is possible to defecate upwards and b) you can’t fly power-off aerobatics in every aeroplane. But otherwise the willing Zlin will do virtually everything else you ask of it, reliably and repeatedly.
So what is the moral of this tale? Mostly that I−universally acknowledged to be (by family and friends at least) the world’s most parsimonious man, with much income needed, no fewer than four unserviceable aeroplanes to fix, and a wife I hadn’t seen for thirteen weeks−would nevertheless drop absolutely everything for days on end in favour of flying aerobatics in sunny weather and a strong, honest and responsive aeroplane.
And I say this as a former 33-year airline pilot who never exceeded 25 degrees of bank.
Nevertheless, while I would sell my soul for an hour in the Coopers’ Zlin, I find it difficult to explain that attraction in ways a non-aerobatic pilot might understand...
Surely flying should not be just about droning from hither to yon in a single dimension−however sizzling the speed or fancy the avionics−clearly that could never supplant the sheer visceral pleasure of throwing an unbreakable aeroplane joyously around the skies, carving curves in the air like a delinquent adolescent squealing smoky donuts in a stolen car.
There is nothing in life like the thrill of aerobatics for making you feel free, unfettered, liberated, master (or mistress) of your destiny – Master of the Universe, indeed.
Please don’t waste your hours droning around in just the single, straight-and-level dimension, flying track lines to some other airfield for that £100 coffee. Don’t go right from getting your hard-won PPL to the slog of an IMC Rating, or a Night Rating or a Twin Rating.
How boring would that be? How boring would you be?
Break those surly bonds of gravity… dance aloft on laughter-silvered wings! Explore all three dimensions: go and fly some aerobatics! You don’t have to get the rating or even fly aeros solo.
Just go up with an instructor to fly a single loop or aileron roll−then see how you feel. If you only ever want to fly aeros with an instructor for confidence, that’s fine. The human body wasn’t designed to be thrown around the sky−not yours, not mine. Everyone takes time to get used to it.
Take your time. Approach aeros gently.
But just one time, go and experience the god-like sensation of turning our world upside-down, I urge you. Be a real three-dimensional pilot for once in your life.
Who knows, like me you might become a lifelong addict... and frankly, what better addiction could there be?