Flight Test: Yak-50
PUBLISHED: 13:34 13 January 2017 | UPDATED: 13:34 13 January 2017
Lee Howard SINGLE USE PILOT MAG ONLY
Taming and displaying the Russian bear has been a challenge and a dream come true (but don't tell my little Pitts!)
Words: Lauren Richardson
The rumble of the Russian radial reverberating through my body is accompanied by an unmistakable smell – a mixture of fuel, oil, smoke and well-worn metal. The world passes beneath me, dreamlike, as I stare out through the canopy of this pure-bred aerobat, descendent of so many famous fighters. There is something indescribable about this machine that will be forever engrained in my soul.
I am first and foremost a Pitts pilot. I’ve been flying the diminutive biplane for a few years now and have spent the vast majority of my airborne time with two complete sets of wings strapped on and a flat-four Lycoming ahead of me. Every time I come back down I am aware that, although mostly docile, she can transform into a raging demon at a moment’s notice. So my reaction to AT Aviation’s invitation to fly the Yak-50 was split between confidence and terror about taking a seat in one of my ultimate bucket-list aircraft.
The Yak-50 was designed by Yuri Yankievich and Sergei Yakovlev, son of Yakovlev company founder Alexander Sergeyevich Yakovlev. It first flew in 1973 as the company’s latest and greatest single-seat aerobatic aircraft. Developed from the two-seat Yak-18 series, the first post-war light aircraft produced by this legendary warplane builder, the Yak-50 was lightweight but strong, featuring a stressed skin monocoque fuselage and powered by the new Ivchenko Vedeneyev M14-P engine producing 360hp. It was the ultimate Russian competitor on the aerobatic scene.
In fact, flying against the by then legendary Pitts Special and the new Zlin 50 at its first competitive outing at the World Aerobatic Championships in Kiev in 1976, the Yak-50 took first and second place in the men’s championships and first to fifth in the women’s competition, as well as overall men’s and women’s team prizes.
Only 312 Yak-50s were ever built, almost all for the Soviet military, and the majority were broken up, under orders, when it was superseded by the Yak-55. It is estimated that only between sixty and seventy currently survive worldwide. These days, the Yak is no match for modern composite monoplanes – the Extra 330SC, XA41 or MX-S – but I would argue that it provides a much more rewarding experience for many pilots.
As much as I love high performance aerobatic aircraft, I am biased toward more traditional, historic machines with soul and character, and they are qualities the Yak-50 has in abundance.
As a Lycoming afficionado, the most difficult part of my transition from Pitts to Yak display pilot was learning to operate the nine-cylinder Vedeneyev properly. This isn’t the simple ‘turn the key and go’ style of flying so many of us are used to – lots of preparation and care are needed to operate one of these machines safely.
Originally designed to carry just 55 litres of fuel (some say in order to prevent pilots being able to defect from the Soviet Union in it), most Yak-50s have had additional tanks fitted, doubling capacity and endurance. As an aid to the innocent, this one has had the actual fuel levels skilfully added by hand alongside the beautifully made, original segmented Russian fuel gauge in the centre of the panel.
Our Yak can carry 118 litres, which, depending on how much of a hurry you’re in, equates to over two hours flying time. Burning around eighty litres per hour with both throttle and prop firewalled, however, it’s best to set around 70% RPM and 700mmHg manifold pressure in the cruise, as this yields a significantly less eye-watering burn of around fifty litres per hour at a speed of around 250km/h or 135kt.
Prior to climbing into this high performance single-seater, I first flew a couple of sessions in a two-seat Yak-52 to familiarise myself with the systems and idiosyncrasies of the Yakovlev line. A common misconception is that the Yak-50 is a single-seat, tailwheel version of the Yak-52 but this is the wrong way around – the Yak-52 military trainer was actually a development of the Yak-50 and Yak-18. Therefore, it comes as no surprise that virtually all of the systems in both aircraft are the same.
The 52 is undoubtedly the best aircraft for training before strapping into a 50. The only notable differences in operation are that the 52 has the third wheel at the wrong end of the aeroplane (yes, I am a tailwheel snob) and it has flaps, while the significantly lighter Yak-50 does not. Both feature a semi-retractable undercarriage, powered by the aircraft’s compressed air system.
One point to note is that the 50 doesn’t have the surprisingly comforting undercarriage indicator wands that poke through the upper wing surface of the 52 when the wheels are up. You have to rely entirely on the warning lights in the cockpit and the hefty clunk when the undercarriage locks into your chosen position.
Starting this radial Russian bear begins with some gentle coaxing − when the engine is cold, it is necessary to pull it through first for nine or ten blades. This can be quite tiring but essential to move the oil around from where it will have pooled in the bottom cylinders, lest the dreaded hydraulic lock becomes a problem. I’ve been taught that if oil is still running out after it’s been pulled through nine or so blades, it’s best to keep on going until it stops. Once suitably exhausted, it’s time to move onto the fun bit.
After jumping into the cockpit, strapping in, donning helmet and gloves, switching on the electrics and reaching down to my left to turn on the main air system valve, I’m ready. I discovered fairly early on − somewhat embarrassingly − that if I neglect the last of these steps and leave the air turned off, not very much happens because it powers not just the undercarriage mechanism and brakes, but also the engine start.
Next it’s time to prime the fuel system using the hand-pump on the right of the instrument panel, first turning it to ‘sistem’ [sic] and watching the fuel pressure gauge register pressure from two or three strokes, then turning the primer to ‘cylinder’ and giving it three or four more pumps.
This part of the process is more enjoyable if carried out with the help of an assistant, who pulls the propeller around to let me pump fuel as each blade passes the twelve o’clock position, allowing fuel to be more evenly distributed around the cylinders. Pulling the primer out whilst still set to ‘cylinder’ allows the opportunity to throw an additional squeeze in during start if she seems a bit reluctant. Once the engine is running happily, the primer must be pushed in and locked in the central position.
With everything primed and ready, it’s finally time to kick the bear. I usually wish I could grow a third hand at this point as there’s a definite knack to holding the stick back, with the brakes held on using the single stick-mounted hand lever and controlling the throttle, magneto switches and starter button all at the same time. Some Yak operators use a Velcro strap to hold in the brake lever but I’ve yet to try this.
My chosen method is to use my right hand on the stick/brake lever, set the throttle to idle, put my thumb on the starter, and position two fingers of my left hand on the magneto switch, which is in the off position at this point as the first fires of the engine will be using a shower of sparks.
A press of the starter button results in a cacophony of whines and wheezes, followed by a barking growl, as a great puff of smoke engulfs anyone foolish enough to be stood behind as the cylinders start to fire. Releasing the starter, I flick both magnetos on, before moving my hand to the throttle control with a quick finesse to induce a happy-sounding nine-cylinder burble. Having made a successful start the bear is now very much awake!
Taxying and takeoff
Arguably, and perhaps surprisingly, the most difficult part of operating a Yak-50 is taxying. I learned this the hard way prior to my first flight.
Having started up and dutifully waited for the oil and cylinder head temperatures to rise sufficiently to let me apply some power, I promptly discovered just how challenging the big Russian can be on the ground. She isn’t a twitchy shopping trolley in the same vein as the Pitts, but a more complex challenge altogether. Firstly, you can’t see forward − and it’s not something that can be remedied by using half the clubhouse sofa cushions. No matter how high you sit, you simply cannot see a single thing in front!
The Yak’s nose is long, wide and right in the way, much more so even than the notoriously tricky Pitts. I quickly found that, with loose shoulder straps, an open canopy and some contortion, I could see a little if I stuck my head out to the side, but the only real way to see forward is using an exaggerated zig-zag style of taxying.
This wouldn’t pose an issue if it weren’t for the tailwheel lock. It is extremely effective, to the point that, with the pin engaged and the wheel locked straight, no amount of differential braking pressure will make the beast turn in anything like a sensible radius. In fact, it barely turns at all. This is brilliant when landing but not so great when trying to edge past a parked Cessna.
To taxi, the tailwheel needs to be unlocked, in which state it happily free-castors and the aeroplane behaves in a much more sensible fashion. The thing is though, to unlock it feels decidedly wrong as it requires you to move the stick forward. Eventually I figured I’d given the guys at AT Aviation enough entertainment so, with some trepidation, I gradually nudged my hand forward… and lo! I could suddenly turn and the Cessna was safe.
Having eventually made my way to the end of the runway using a combination of neck-cricking sideways-slalom peeks, unsteady zig-zags, nervous stick movements and some decidedly jerky braking, I had by now broken into a sweat and was all too aware of the amusement my efforts had given my colleagues, but at least the engine was warm enough to do the power checks and get going.
With power checks and propeller exercise complete, I made sure both the oil cooler flap adjustment and ‘gill’ controls were set correctly. The oil cooler setting tends to stay put and not need adjusting in flight, but the gills around the front of the cowling − a fan-like array of shutters that essentially controls the cylinder head temperature − need attention. Setting them fully open for takeoff is essential or else the CHT needle rapidly approaches the red end of the gauge, causing even more sweating. Once airborne they need adjusting to maintain the CHT in the optimal range, which is critical with the Ivchenko engine but pretty simple to do.
My first takeoff proved quite a shock to the system. The cloudbase was only around 1,200 feet over the airfield, which shouldn’t have been a problem as all I wanted to do was take off, faff around for a few minutes, then come back for tea and medals. I didn’t need oodles of height, or so I thought.
By now past the nervousness of starting up and the stressful taxi, I was well and truly in the zone when I took a deep breath and opened the throttle. The bear got a big kick up the backside and roared loudly as the runway started disappearing at a startling rate. I found myself airborne before I was really aware of it, or indeed entirely ready.
Pulling up to climb, I decided I’d better retract the undercarriage and glanced inside to find and move the lever up on the left side of the panel. By the time I looked back outside I realised I’d grossly underestimated the aeroplane’s rate of climb and equally overestimated the weather conditions – everything outside was grey.
Thankfully, this was only a momentary excursion as I hurriedly nudged the nose down and pulled back the levers from the ‘raging manic beast’ takeoff setting, breathing a sigh of relief when the ground popped back into view and I could see green again. Settling at a nominal cruise setting, I spent the next few minutes flying gentle circles, doing distantly remembered breathing exercises to bring my heart rate back into the green arc. I found out afterwards that the maximum climb rate of the Yak-50 with all 360 horses pulling is over 3,100fpm!
Stalling, spinning and aerobatics
With my inaugural flights completed, I began my display workup. One of the big questions in my mind causing minor trepidation was what this single-seater would be like in a spin. Would she become a wild animal in the autorotation, thrashing and aggressive, or would she be meek and submissive? The answer was apparent from the moment I started closing the throttle to induce the stall. She is incredibly well mannered, calm and patient with her pilot, proving to be a remarkably docile and consistent creature.
The stall came with no surprises, speed dropping away quickly with the throttle pulled back and the nose high. She showed only a very slight tendency for one wing to drop before the other, something briefly noted in my mind before I kicked in full right rudder and continued pulling back hard on the stick. Feeling almost like a slow-motion sequence in a movie, the wings stalled and the machine started to yaw, then dropped a wing to begin the rotation.
The spin actually felt pretty slow, verging on ponderous − not the whirlwind of motion I’m used to with the Pitts. I found myself wanting to use both hands to hold the stick back as she felt surprisingly eager to exit the spin, a very commendable characteristic in many ways.
A little adjustment with some aileron and slight variation in elevator input felt like it may have helped stabilise the minimal amount of oscillation as we went through our second and third rotations. I repeated the exercise a few times, to both right and left, neither direction providing anything in the way of alarm or surprise.
Recovery was always a simple matter of just deciding to stop. Releasing back pressure and rudder made the rotation stop quickly and without conscious thought. Having spoken to others more experienced than me in these aircraft, I’m confident she provides an almost viceless aerobatic platform. The key characteristics of consistent handling and simple spin recovery give absolute confidence when it comes to trying more advanced aerobatic manoeuvres.
For most of my aerobatic sorties in the Yak, I set the propeller to 80% RPM (fractionally below the max continuous setting of 82%), with the throttle usually set to give 800mmHg of manifold pressure. I’ve played with her set to 70% and 700mmHg and this works well for low-energy aerobatics but I much prefer the additional power to hand with the higher settings. For anything except the most advanced aerobatics I’d say there’s no real need to fly full throttle (rather good fun but expensive).
Having accelerated to around 300km/hr (162kt) in a gentle dive, I pulled back on the stick for a simple loop, feeling something magical in the joy with which this machine flies, soaring upward with only a relatively gentle back pressure required. The aeroplane is a thoroughbred – she looped with precision and class, gentle yet powerful, inducing a huge grin as we floated over the top.
I felt like I was flying a fighter, the powerful engine and controls coupled with great visibility make this a truly hedonistic aviation experience. The grin didn’t leave my face for the rest of the flight.
After a bit of looping and whooping I wanted to try out the Yak’s notoriously heavy roll characteristics and made the mistake of trying to aileron roll as I would in the Pitts − with one hand − but she really is heavy for a former world aerobatic champion, and this took me a little by surprise.
I managed to complete a scrappy roll with only partial aileron input, having by then realised that to fly her well I would need both hands and a degree of upper body strength. With two hands on the stick and a big heave to get full aileron applied, she goes round much more precisely and cleanly. The Yak-50 isn’t a particularly fast-rolling aeroplane, and requires some determination and commitment along with some pretty hefty rudder inputs to keep the nose where it should be during the roll, but none of it is actually difficult and I soon found myself flying aileron rolls and both two and four point hesitation rolls precisely and with relative ease, albeit with a degree of physical effort.
The other classic manoeuvres like the barrel roll, Cuban eight and simple wingover are all equally straightforward. Unsurprisingly Cuban eights (flown in both forward and reverse directions) require some effort to get the half roll done in a reasonable time frame and with decent precision, but no simple aerobatic manoeuvre yields any great surprise.
The Yak flies both graceful, flowing classical style aerobatics as well as aggressive Unlimited manoeuvres with aplomb. Stall turns have been my one surprise as they do require additional technique to get around the excessive gyroscopic effect from the huge, geared propeller and powerful engine.
Returning to earth with the Yak didn’t provide any particular worries, even on the first go. A decent width undercarriage, nice long tail and effective tailwheel lock predictably all combine to make the aeroplane a big pussycat on landing.
I flew my approach using the book figure of 150km/hr (eighty knots) and slowed to around 130 (seventy) as we got to the threshold. I let her slow further as we touched down and found her responsive the entire way down. I touched the main wheels first in a ‘wheeler’ configuration, not applying any braking as we ran on and I let the tail settle, bringing the stick fully back and engaging the tailwheel lock.
She ran beautifully straight as I applied the brakes gently, keeping the rudder neutral to prevent any steering effect and brought us to a stop. I smiled and breathed a big sigh of relief.
Subsequent landings have been similarly straightforward, with the usual mixture of shockers and greasers although none of my scrappy landings can be blamed on the aeroplane. She’s a breeze to play with on smooth grass and docile on tarmac. The only thing to watch for were crosswinds, as the relatively weak undercarriage construction means a great deal of care needs to be taken to avoid too much side loading on the pivots. The book actually states a crosswind capability of just 12km/hr (seven knots) but a little more than this isn’t a problem, so long as appropriate care is taken.
Having now flown a good number of sorties over several hours and a couple of displays, I’m completely smitten. Turning heads even when silent on the ground, this beautiful Russian is a serious piece of hardware and a joy to fly. The Yak-50 is truly one of the great aerobatic aeroplanes of history. I’m looking forward to many more happy hours and displays to come.
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