Rare Aircraft – Moose Tales: Yak-11 D-FJII @ LDVA

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Even though summer is in full swing – with matching weather to boot – the airshow season in Croatia has nevertheless been uncharacteristically subdued of late. While there still are many small local shows around, large events are few and far in between, with even some long-standing and popular gatherings failing to make an appearance in 2016. The hopes of the nation had therefore been invested in this year’s Croatian International Airshow Varaždin (CIAV), which had – listing everything from ultralights to multiple combat jets – promised to be one of the country’s biggest and most exciting shows of the decade.

While the full guest list had indeed made for a mouth-watering read, the attendees that had caught my eye the most were (naturally!) rare lighties from the East, including the L-200 Morava (one of which had previously been featured here), Europe’s sole airworthy Aero Ae-145, a rare Yak-11, an even rarer Soko J-20 Kraguj counter-insurgency piston single – as well as two Soko G-2 Galeb jet trainers.

Unfortunately though, various issues beyond the organizers’ control had eventually whittled the list down considerably, with my anticipated oldies being particularly hard hit. The Morava and Aero had been unable to attend due to other commitments and a bit of unfavorable weather enroute from the Czech Republic, while one G-2 and the J-20 had to throw in the towel when mechanical problems prevented them leaving their bases in Serbia. This had only left the other G-2 and Yak-11, the latter of which had quickly become the main target of my visit. While not the first of its type for my camera, the attending example was nevertheless the first one I could get close up to – allowing me an opportunity to put together enough material for a short (but interesting) photo report… 🙂

Taking a creative shortcut across the grass while returning to its parking position following a fine display. With visibility over the nose being virtually non-existent, the Yak-11 (in common with many taildraggers) has to constantly weave from side to side during taxi to allow the pilot to see where the aircraft is going. Since the -11 has a non-steerable tailwheel, all steering is done through differential braking, which can be a cumbersome and tiring experience – making it easier to simply taxi in a wide arc wherever possible.

The Moose Is Loose

A design that is not really easy on the eye, the Yak-11 can trace its roots back to 1944 and the exploits of the diminutive – but superlative – Yak-3 fighter. A lightweight development of Alexander Yakovlev’s first military design – the Yak-1 – the -3 had gained an enviable reputation for crisp, precise and forgiving handling, as well as low altitude maneuverability that few (if any) contemporary fighters could match. The main key to its success was its low weight and high power, with its 1,300 HP Klimov VK-105 V12 having to pull just 2,700 kg all-up – which makes for roughly one horse per every two kilos of loaded mass*.

* however, as impressive as it is, this figure only tells half the story. Among the Yak-3’s European short-range interceptor contemporaries, the Spitfire XIV – still regarded as one of the best of the Griffon-powered Spits – could boast 2,200 HP spread over 3,810 kg, giving an even more astounding 1.7 kg/HP; however, this numerical advantage was – in terms of outright maneuverability – somewhat blunted by an extra ton in mass, giving the Yak a slight edge especially in the dense air at lower altitudes.

Interestingly, the -3’s main rival, the Bf.109G, was almost equal on paper, with 3,400 kg and 1,455 HP for 2.3 kg/HP. But, like the Spitfire, its added bulk did not help its case – nor did the type’s characteristic high wing loading, which made it an inferior performer in the type of prolonged low-altitude turning fight in which the Yak-3 excelled.

Unsurprisingly, its successful record in duels with the Luftwaffe had pretty quickly led to attempts of increasing its kinetic performance even further, in the hope it could even take on the Me-262 with relative ease. Unfortunately, the only suitably powerful Vee engines available at the time were the problematic VK-107 and 108, both of which were pushing the limits of the Union’s development capabilities – and suffering from frequent overheating, failures and fires as a consequence. In an effort to get around this problem, Yakovlev had decided to swap the existing VK-105 for a tried-and-tested radial engine, hoping its simplicity, availability and greater power – not to mention a shorter time-to-service – would offset the increased drag and redesign effort necessary**.

** going radial on a Vee engine airframe was not really a new idea per se. The UK in particular had undertaken several similar efforts during the war – though for different reasons – most notably on the Avro Lancaster bomber in 1941 (creating the Bristol Hercules-powered Lancaster B.II) and the Hawker Tempest fighter in 1943 (taking the form of the Tempest F.II with a Bristol Centaurus unit).

The engine that was chosen in the end was the 1,850 HP Shvetsov ASh-82FN 14 cylinder twin-row unit, at the time one of the USSR’s most common large radials – and, interestingly, also a thorough development of the equally famous Wright R-1820 Cyclone. The installation of a shorter, but heavier engine had also required a tweak of the wing, which had gained a small increase in span and was moved slightly forward to compensate for the new mass distribution.

So equipped, the first (and only) prototype would begin flight testing in early May 1945, quickly demonstrating a 34 km/h / 17 knot increase in speed, as well as markedly improved climb and high-altitude performance – all due to the extra torque generated by the two additional cylinders and 6 liters / 366 cu in more cubic capacity.

However, while this modification was becoming all it was hoped to be, it had arrived too late to make any impact on the war. By the time the prototype had taken off for its first flight – 29 April 1945 – most of Berlin was already in Soviet hands, and the Luftwaffe had long ago ceased to be a functioning force. And while history would show that piston fighters could and would remain in service well into the 50s, the promise of the jet engine had instantly hammered a major nail into the coffin of the radial Yak-3 as a front-line fighter.

Fortunately though, the development effort had not gone to waste. At the time, the vast majority of Soviet flight training was performed on the Polikarpov Po-2 biplane, which – while a sterling design in itself – could in no possible way prepare students for the rigors and requirements of the modern combat-proven high-performance fighter. While there were various two-seat training modifications of such machines available already in 1944 (such as the Yak-9B and La-7UTI), they were few and far in between – and since they took away from the combat strength of the units involved in the actual fighting, only a handful of flight schools could ever get their hands on them.

What was needed here was a relatively modern aircraft, low wing, with a closed canopy, retractable landing gear, flaps, constant speed propeller and all the goodies (and most of the weaponry) that could be found on actual in-service aircraft. It also had to be able to adequately teach students about high-performance flight – while still remaining docile and predictable enough to stop them killing themselves. And lastly, it needed a robust and simple engine that would be more tolerant to student misuse than the sophisticated V12s of front-line machines.

Ticking pretty much all of the boxes, the radial Yak-3 had promised to be a natural for this role. All that was needed to turn it into a trainer was the addition of a second cockpit for the instructor – and swapping the too powerful ASh-82 for the seven cylinder 700 HP ASh-21 (itself essentially a single-row version of the former) whirling a VISH-IIIB-15 or VISH-IIIB-20 two-blade constant speed prop. Flying for the first time in 1946, the new aircraft would soon be given the designation Yak-11, becoming known as Moose in NATO parlance.

In flight testing, the -11 had soon proved that its Yak-3 DNA still ran strong, with the only major design criticisms being levied at the low power available. While 700 HP may sound like a lot for a two-seater, it still had to haul 2,400 kg of mass, making for a chunky 3.4 kg/HP. Even though this was actually slightly better than on similar trainers elsewhere – the T-6 Texan, for example, commanding 600 HP for 2,550 kg of mass – it had nevertheless meant that the Yak-11 was quite sluggish in the climb, and had quickly become known for its lengthy take-off roll. One particular problem, often mentioned, was that during a go around in full landing configuration, the aircraft would barely climb – while a reduction in flap angle in an attempt to clean up the airframe would produce an alarming drop in altitude until the speed built up (once in level flight however, its Yak-3 legacy had meant it was one of the faster trainers out there). Some reports also mentioned a lack of longitudinal stability in production aircraft as compared to the prototype; this – and the lack of power – had meant that the -11 often flew without its full fuel load, with 150 kg being the standard versus the 270 it was actually able to carry.

There were other issues as well; in common with many Soviet light aircraft built in the years following WW 2, the production quality of the Yak-11 had left a lot to be desired. A major source of bother were the effects of long-term exposure to the elements, with wood and fabric components – and particularly the paint – requiring constant intensive care and frequent replacement. Reports also mention cracks in the fuselage structure and control surface mountings – as well as leaking fuel tanks – but most of these problems would eventually be resolved with various production line fixes and general improvements in build quality.

Despite these issues, the Yak-11 would quickly become the mainstay of the USSR’s post-war training fleet – arguably not just because of its handling qualities, but because it was the only suitable and proven aircraft available at short notice and in quantity. By the time production had ended in 1956, 3859 examples had been made, 3152 at the No. 272 and No. 292 Aviation Plants at Leningrad and Saratov respectively – and 707, under the designation C-11, at the Let works in Kunovice, Czechoslovakia between 1953 and 1956.

A mint C-11 taxis in following its performance at a rainy 2007 Kecskemet Airshow. Externally indistinguishable from the regular Yak-11, the C-11 had only differed in minor on-board equipment specifications and replacement of some wooden parts with metal.

Regardless of their factory of origin, all Yak-11s had shared the same flight characteristics, and could be employed in a number of different training scenarios, including intermediate flight, gunnery and reconnaissance training. While its on board equipment would vary considerably throughout its production run, the Yak-11’s armament options had pretty much stayed the same, consisting of a single Berezin UBS 12.7 mm synchronized machine gun firing through the propeller arc (swapped in 1955 for an Afanasyev A-type gun of the same caliber at the request of Czechoslovakia) and two hardpoints for 50 kg of bombs located just outboard of the main landing gear.

Unsurprisingly, its capabilities, production numbers – and the fact that it had the market mostly to itself – had meant that the -11 had found widespread use even outside the Warsaw Pact. Thus, examples could be found even in Albania, Algeria, Angola, China, Egypt, Iraq, Mongolia, North Korea, Somalia, Syria, Vietnam and Yemen. However, the most interesting operator was – hands down – Austria, which had between 1956 and 1965 flown four C-11s (and four Yak-18s) left behind – still in their crates! – by the withdrawing Soviet forces in 1955.

4C-AF of the Austrian Air Force at Zeltweg (Airliners.net)
4C-AH of the Austrian Air Force at Graz (Airliners.net)

Egyptian Holiday

Our particular example can, however, also boast an interesting story 🙂 . Part of a batch of 40 or so Yak-11s intended for Egypt during the early 50s arms buildup, D-FJII was completed in 1952 – likely at the No. 272 works in Leningrad – sporting the serial Y-5434***.

*** some online sources state that all examples delivered to the Egyptian AF were in fact C-11s; however, D-FJII’s current owners state it had been manufactured in Russia one year prior to the start of Czechoslovak production. Additionally, while quoted in all the sources I found, the serial is at odds with those of most other Yak-11s/C-11s, which come in a seven-digit numeral-only format. The reason for this difference is unknown.

However, the tense political and military situation prevailing in Egypt at the time – exacerbated by the 1948 Arab-Israeli War, and later even more so by the Suez Crisis – meant that finding accurate, unbiased and uncensored information about military aircraft dispositions was near impossible, making D-FJII’s history in Egyptian service very hard to trace. Various incomplete production lists suggest that the ordered aircraft may have been delivered in several batches – which would, on account of its production year, make D-FJII part of the first. Other bits and pieces of information suggest that it had likely been based at Bilbeis Air Base in the Nile Delta – the location of the Egyptian AF’s main flight academy even today – remaining in service for less than a decade before the entire fleet was withdrawn from use in 1970.

What is known for certain is that in 1982, aviation restorer Alain Capel had discovered the hulks of 41 examples stored – in a pretty appalling state – at an Egyptian AF dump at Al Akhaa Air Base****. Over the course of the following year, Raymond Capel, as well as Jacques Bourret and Jean Salis of the famous aircraft collection Amicale Jean Baptiste Salis, had managed to persuade the Egyptian government to allow them to buy the entire batch, eventually transporting the lot by container ship to the French port of Marseille in 1985.

**** many sources state that the aircraft had been interred at the “El Aakha” Air Base. However, no such place actually exists; the name is likely a transmutation – through numerous rewrites – of Al Akhaa, a real place with a real air base located almost within spitting distance of the Yaks’ former home of Bilbeis.

Arriving soon afterwards at the mecca of French historical aviation – the airfield of La Ferté-Alais (LFFQ) near Paris – many of the aircraft would be taken under the wing of a dedicated restoration team, who had been tasked with the painstaking process of sorting through the entire mess, hand-picking good parts, reconditioning what could be saved and cannibalizing what could not. Nearly a decade of their perseverance would eventually pay off – and pay off in full – since the dozen or so examples to come out of the process nowadays represent the vast majority of the world’s remaining airworthy Yak-11s/C-11s 🙂 (some having even been converted to single-seat models resembling the original radial Yak-3 prototype).

Borderline

What would become D-FJII had, however, followed a slightly different path. Soon after arriving at Le Ferté-Alais, it would be sold to a buyer in Switzerland, being transported – as is – to the border town of Lausanne for restoration by aircraft engine specialist Philipe Joyet. Having been rebuilt and cleaned up to a fault, it would fly for the first time – again – on 8 July 1995, becoming F-AZIO soon afterwards. For the next decade, it would be based at Lons-le-Saunier Airfield (LFGL) on the other side of the Franco-Swiss border, sporting a two-tone gray scheme once carried by the Yak-3s and Yak-9s of the Normadie-Niemen, a highly-decorated squadron of Free French pilots flying with the Soviet Air Force during WW 2.

Reportedly one of only two fully original Yak-3s remaining, 4 is an actual ex-Normadie-Niemen machine nowadays displayed at Le Bourget (LBG/LFPB). The paint scheme is broadly analogous to the one initially worn by D-FJII.

In 2005, it would be sold to Meier Motors of Germany, becoming D-FJII and operating out of Bremgarten Airport (EDTG) near Freiburg – located, you guessed it, just off the French border 😀 . Its stint there would be comparatively short lived though; in a pleasing bit of circularity, it would return to its spiritual home of Le Ferté-Alais in 2011, rejoining the Salis collection while retaining its German reg. Interestingly, in 2012 it would receive its current paint scheme, with the darker gray tone replaced by olive – and the underside repainted cyan from its original light gray (also one of the schemes used on Normadie-Niemen aircraft).

An Egyptian-French-German Russian in Croatia

Meanwhile at CIAV, D-FJII would – sadly – manage to fly only a five minute display due to time constraints… but its ample time on the ground and a very friendly crew had nevertheless allowed me opportunity to peek around and briefly document this charismatic and beautifully ugly machine… 🙂

Even though it is based on one of the smallest fighters of WW2, the Yak-11 is still a sizable machine! With its pronounced nose-up stance – needed to ensure adequate propeller ground clearance in case students became too enthusiastic with the brakes – the -11 is quite hard to clamber up onto, made all the more difficult by D-FJII’s lack of a handy step behind the wing.

A profile only Father Yakovlev could love. Note also the mixed construction: wood for the front fuselage (minus the cowl) and fabric for the rear, both on top of a steel frame. The wing, however, is metal in and out, with only the control surfaces covered in fabric.

A peek into the front cockpit. While they may be unusual by today’s standards, the ergonomics and layout of the panel do have some interesting touches: the dominating artificial horizon intended for easy reading during aerobatics or instrument flight; the engine gauges grouped generally out of view, but tilted upwards toward the pilot; and all system and navigation controls set within reach of the left hand.

Like many Soviet light (and not so light) aircraft, the Yak-11 makes extensive use of pneumatics, as opposed to the hydraulic setup favored in the west. While air systems are hard to accurately meter out and pretty coarse in application, their advantages include a lower system weight, easier replenishment – and, critically, more predictable behavior in the diverse temperature ranges experienced across the Soviet Union. On the Yak-11, the pneumatics are responsible for actuating the flaps, landing gear and brakes – and are fed from two large air bottles located on the left side on the cockpit (one of which is visible above). Both bottles can be opened and closed by rotary valves next to the seat – which, essentially, are analogous to hydraulic on/off switches on western aircraft.

Sources (in alphabetic order):

Photo Report – I have nothing to offer…

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… but sweat, dehydration, sunburn and flight hours 😀 . Okay, Churchill may not have had the spring/summer flying season at Lučko in mind when he uttered his famous phrase back in 1940, but in this custom form it does go a long way to describing events at the field these past few weeks 🙂 . With out traditional summer anticyclone parked very firmly over the entire region, we’ve been graced with fantastic flying weather for days on end, allowing out entire fleet to go out and stretch its wings. And while the temperatures did let the side down – with 40 Centigrade on the apron not even being newsworthy – we’ve nevertheless persevered, allowing me to bring you another photo series of life in Croatian GA (and beyond)… 🙂

The Carryall in its element: on grass under sunny skies on a beautiful spring day. An aircraft with a rich history in the country, BKS was produced back in 1977, entering service with local operator Pan Adria the same year. Used for tailwheel conversion training and crop dusting, it would pass to the Viša zrakoplova škola flight school a few years later, where it would serve as an IFR trainer. Following the school’s collapse in the late 80s, BKS would end up in the fleet of Aeroklub Zagreb, where it was stripped, lightened and turned into a skydive aircraft – a role it fulfills even today. An interesting personal detail is that this aircraft seems to follow my family around, starting with my dad who used to work in Pan Adria, mom who used to work at Viša zrakoplovna škola – and me currently flying it on behalf of AK Zagreb.

Another look at our charismatic fuel-to-noise converter. Powered by an 8.5 liter/520 cu in engine developing 300 HP and whirling a 208 cm/82 in diameter prop – which is well into the transsonic region on take off – BKS is not the most conspicuous machine around, and can – during favorable winds – be heard all the way to the center of Zagreb, some 10 km/5 NM away…

Definitely one of the more interesting aircraft I’ve come across over the years! Sporting an unusual configuration for what is essentially a motorglider, the HB-21 is quite the performer despite its frail looks, easily rivaling the Piper Super Cub in the climb. Indeed, OE-9129 was bought specifically to replace PA-18 9A-DBU in the glider tow role, with trials revealing it’s more than a match even when hauling a heavy glider such as the Let L-13 Blanik…

A scene straight out of WW I as one of Lučko’s most famous residents flies leisurely overhead. Lovingly crafted over a period of several years – mostly out of materials found in hardware stores – XCA is a modern replica of the first proper aircraft built in Croatia: the P-3 of 1910 (designed by inventor Slavoljub Penkala). Not exactly a one-for-one replica, the CA-10 includes a few aerodynamic improvements to make it easier to fly, as well as an 80 HP Rotax 912ULS in place of the extinct Laurin & Klement inline.

The (mostly) fine weather had also lured out the air force, allowing us to play a bit of spot the differences! Even though they are essentially the same aircraft underneath, the legacy Mi-8MTV-1 and the modern Mi-171 do diverge in a number of details – the most obvious being the 171’s flat rear ramp. Other more subtle changes include the additional forward fuselage door – which had necessitated the relocation of the aircon unit to the top of the fuselage – and the Doppler Navigator antenna array moved further back down the tail boom. Intended to also provide at least some of the capability of the country’s long decommissioned Mi-24 fleet, the 171s also sport some additional combat equipment, including bolt-on armor plating around the cockpit, flare dispensers (above the CroAF roundel on the rear fuselage), IR jammers (at the back of the gearbox assembly) and provisions for carrying up to four B8V unguided rocket packs.

Reasons for getting up at 4 AM to go flying: here’s #1… beautifully smooth air, absolute quiet on the frequency, an agreeable 26 Centigrade aloft – and a fantastic view of sleepy Zagorje as I ferry DMG to Varaždin for servicing at 5:30 AM.

Even though it is relatively busy even at the worst of times, on this morning Varaždin appeared to be host to a mini Cessna convention, with seven 172s, one 182 and one 210 lining the main taxiway and apron. The culprits for this threefold increase in Cessna numbers were the seven 172s from Bulgaria and Serbia, in country on a fox immunization contract and for the time being operating out of Varaždin…

Easily mistaken for a brand new Skyhawk SP, this mint 1978 172N is seen rolling gently towards the main hangar for some minor maintenance. Part of the aforementioned Bulgarian-Serbian fleet, AIA is equipped with a bare bones interior and a special pellet dispenser in place of the regular baggage door. In immunization operations, the aircraft is manned by a crew of two, with the second member manually feeding the dispenser with pellets from chilled boxes (kept overnight in a refrigerated truck trailer).

Photo Report – The Force 450 Gale: Serbia’s SILA 450 UL

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Back in 2012 while on a short visit to Belgrade, Serbia, a friend and I had decided – in true Achtung, Skyhawk! tradition 😀 – that we might as well do some proper sightseeing and head out to the old UTVA aircraft factory in Pančevo, a couple dozen kilometers up the main road. Once the powerhouse of Yugoslavia’s aircraft industry, this enormous factory was, among other things, responsible for the most ubiquitous light aircraft in the country’s history – the much maligned UTVA-75 – a machine that, despite all its faults, had quickly come to dominate aprons across the land (and the occasional newspaper accident column 🙂 ). Singularly robust machines – the DC-9s of the light single world – many 75s continue to soldier on even today, with a select few also having seen combat action as impromptu light attack aircraft during the turbulent 90s.

By 2012 however, the factory’s shine had long gone and its successes largely forgotten. A dilapidated ruin that had been heavily damaged during the 1999 NATO air strikes, the factory exists today as a rump facility at best, fiddling with a handful of low-scale projects on a thin shoestring budget. While a sad sight in its own right, the view that had greeted us had also represented a striking metaphor for former Yugoslavia’s aviation industry as a whole – and not least of all for the flat spin it had taken during the country’s violent disintegration. Largely scattered across the land, it would – unsurprisingly – take a crippling hit at the start of the 90s war, losing its supplier and customer bases virtually overnight. The widespread financial disasters that had succeeded the conflict never really gave the industry the breathing space it needed to recover, turning the whole aviation landscape into an archaeologist’s playground of abandoned factories, forgotten companies and rotting gate guards.

May the Force be With You

But, in what is a long-overdue resurrection of the region’s large(r) scale light aircraft industry, one manufacturer had nevertheless managed to part the red tape and defy the economic odds, adding its bit to putting the industry back on the proverbial map 🙂 . The company in question is Aero East Europe, a small but efficient unit operating out of a historic workshop in the southern town of Kraljevo, and nowadays well on its way to building up a respectable regional reputation for its original STOL ultralight designs. Fighting its way up the sales ladder against various copies and modifications of the legendary Zenair CH-701, the flagship of the fleet is the 450 kg / 992 lbs SILA 450, an example of which had popped into Varaždin Airfield (LDVA) on 18 January for a brief promotional visit. No prizes for guessing whether I was there… 😀

YU-A102 nice and clean - and ready for its first flight of the day
YU-A102 nice and clean – and ready for its first flight of the day.

Apart from a name that tends to raise eyebrows among Southern Slavic language speakers – literally meaning “force”, but in reality just short for Serbian Industry of Light Aircraft – the 450 appears largely unremarkable at first glance, sharing much of the visual cues of other high wing STOL ultralights. Its specs too (at least on paper) are not enough to set your blood racing; compared to the ICP Savannah XL, the 450’s latest iteration – the 450C – can carry five kg / 11 lbs less, cruises just 6 knots faster, and needs five meters / 16 ft less to take-off and 10 meters / 32 feet more to come to a full stop.

Up front there’s a 100 HP Rotax 912ULS whirling a three-blade ground-adjustable prop – hardly an exciting feature – while equipment-wise you’re looking at electrically actuated flaps, a ballistic parachute recovery system and an optional glass cockpit… essentially the same kit you can get from any other manufacturer out there.

However, once up close and past the preliminaries, a startling number of interesting – and unusual – details begin to emerge 🙂 . The wing, for example, is a mechanically simple affair that makes do without the slats, slotted controls and vortex generators seen on the CH-701 and its spin-offs. Instead, the 450 uses a plain but very thick airfoil profile that simplifies the wing’s internal structure, while at the same time preserving low speed handling and performance and noticeably reducing drag (which will always be high on a STOL wing). Indeed, the 450 can boast a lift-to-drag* ratio od 1/15, quite a bit up from the 1/11 of the Savannah XL (a number also shared with, of all things, the Cessna Skyhawk 🙂 ).

* a common measure of the aircraft’s aerodynamic efficiency, the lift-to-drag ratio – often abbreviated to L/D and sometimes also called the “finesse” – in effect shows how much horizontal distance would the aircraft, unpowered and gliding, be able to cover for each unit of vertical distance lost. The SILA’s 1/15 for example denotes that for every foot of altitude lost, it would be able to glide 15 feet in still air. Scaled up a bit, this means that for a 1,000 ft altitude decrease, it would cover 15,000 ft horizontally (roughly 4.5 km / 2.5 NM). Apart from quantifying the aircraft’s overall aerodynamic prowess, this number also comes in handy during flight planning, allowing you to pick out – in advance – suitable landing fields along your route for the event that your engine decides it has grown tired of working 🙂 .

Another interesting feature are the wingtip fences, which prevent high pressure air below the wing from spilling over the wingtip into the low pressure air above (similar to the winglets of a larger aircraft). Left uncontrolled, this spillover would eventually detach from the wing in the form of turbulence - the infamous wingtip vortex - drastically increasing aerodynamic drag. A similar setup is - uniquely - found on the horizontal stabilizer.
Another interesting feature are the wingtip fences, which prevent high pressure air below the wing from spilling over the wingtip into the low pressure air above (similar to the winglets of a larger aircraft). Left uncontrolled, this spillover would eventually detach from the wing in the form of turbulence – the infamous wingtip vortex – drastically increasing aerodynamic drag. A similar setup is – uniquely – found also on the horizontal stabilizer.

To compensate for the lack of slats and slotted controls at the lower end of the speed range, the 450 is fitted with drooping ailerons, which lower slightly as the flaps pass their halfway travel mark. Combined with the chunky airfoil, they give the aircraft an almost comically low minimum flying speed in the low 30-ish of knots – which was demonstrated to me graphically against the day’s stiff 30 knot headwind at altitude 😀 .

The combination had also acquitted itself well handling-wise, with the 450 displaying unexpectedly impressive flight characteristics in all regimes, high or low, slow or fast. Perhaps its biggest surprise – to a Cessna driver 🙂 – was not what it could do, but the way it did it, with an almost complete lack of aerodynamic drama, pussycat stall and post-stall response, and virtually no buffeting or waywardness anywhere in the standard part of the envelope*.

* in fairness though, I’ve not had much ultralight experience, so I can’t really make an objective handling comparison with other designs… but I can however draw parallels with the similarly sized (though heavier) Cessna 150, which the 450 – in a number of comparable respects – blows clear out of the water 🙂 .

Cabin Space – The Final Frontier

But, even before one gets a grip on the stick, he/she can notice a raft of other nice touches scattered all over the airframe. One that I – standing 1.93 m / 6 ft 3 in tall – can particularly appreciate is the wide and roomy cabin, almost an order of magnitude more spacious and comfortable than that of the 150. Entry and egress is unexpectedly easy from both sides, courtesy of an upward hinged door and wing struts positioned behind the doors, at the joints of the main gear legs.

A
Wide doors and a tall door frame make for remarkably easy entry and exiting – so even types of my height won’t be going around bumping into things. The only criticism I have here is that the sticks are too tall, which makes maneuvering to sit down a bit awkward if you have long legs (and can lead to some minor interior scraping if you’re a bit clumsy).

Once
Once in, there’s plenty of room to stretch your legs and sit upright… though at the limit of the latter in my case. Simple and uncluttered, the cockpit of YU-A102 sported only a very basic avionics fit, tailored to the needs of the German market. Interesting features include the side panels canted towards the pilot, as well as the innovative system switches, which light up when activated (as could have been seen in the above video). The two guarded switches on the left panel are the magnets, while the key slot beside them is not the starter – but the battery master switch. The ominous red handle that sticks into the eye next to my knee activates the ballistic parachute system – and is also guarded for your wallet’s safety.

The view forwards in flight is pretty much on par with that of the 150; however, the large side windows, rear-mounted wing struts and smaller pillars mean the Sila excels when you want to look left, right or down. Like the Savannah, the design also features a small triangular window on the ceiling which helps with ambient lighting and provides some semblance of upward visibility.
The view forwards in flight is pretty much on par with that of the 150; however, the large side windows, rear-mounted wing struts and smaller pillars mean the SILA excels when you want to look left, right or down. Like the Savannah, the design also features a small triangular window on the ceiling which helps with ambient lighting and provides some semblance of upward visibility.

There’s other evidence of the design having been thoroughly thought out. The ailerons and elevators, for example, are actuated by pushrods rather than conventional cables (which are retained for the rudder only), giving a quicker control response and eliminating a number of maintenance issues (delaminating cables being one of them). The space behind the panel is remarkably clean as well, with plenty of legroom and none of the wiring, piping and mechanical whatnot frequently found on Cessnas and Pipers. And – what had caught my attention right from the start 🙂 – there’s a small double L mount hanging from the ceiling just aft of the windshield, allowing you to securely deposit your headphones when not in use*.

* while this is not much of an issue in the grand scheme of things – and certainly not the reason to choose the SILA over any other design – loose headphones can become quite a nuisance. In light Cessnas for example, you either have to hang them from the yoke (not the most practical solution in a small cockpit), leave them on the seat, or, worst of all, put them on top of the panel where they’re exposed to sunlight – and where their speaker magnets can play havoc with the magnetism of the compass.

These practical details continue on the outside as well. The fuel tank caps open, close and latch only with the master switch key, avoiding unintentional flight with the tanks unsecured (and, since we’re on the Balkans after all, also avoiding intentional fuel theft 😀 ). Up front, large access panels are provided on the cowl, allowing for quick inspections and repair without the need to dismantle the whole nose. And – unusually for an aircraft that has a small, light prop and barely treble digits of power – YU-A102 also came equipped with a rudder trim system, operated electrically (like its elevator equivalent) by push buttons located on the tops of both sticks.

Another interesting feature not seen on the CH-701/Savannah/similar is the cut-down rear fuselage, allowing for some semblance of rearward visibility. Two rear windows also give the cabin and airy and less claustrophobic feel. Note also the small black bag visible through the window, housing the ballistic parachute.
Another interesting feature not seen on the CH-701/Savannah/similar is the cut-down rear fuselage, making for decent rearward visibility. The two rear windows also give the cabin a brighter, airy and less claustrophobic feel. Note also the small black bag visible through the window, housing the ballistic parachute.

Certifiably good?

But, while everything said so far sounds very enticing, one other important item still remains – the naughty business of price 🙂 . What you’d eventually pay for one of these naturally depends on what equipment options you’d go for, but the base model – broadly identical to YU-A102 – would set you back about EUR 62,000. Around 30,000 more would get you the top-of-the-line version, equipped with digital avionics (a Dynon Skyview/Garmin G3x mix) and full interior night lighting.

From what I’ve seen while scouting through the European classifieds and various vendor sites, this is a fair bit (EUR 10,000+ to be exact) more expensive than the performance and engine-wise very similar Savannah XL. While at face value this does seem to be a mystery, the SILA’s higher purchase costs can be attributed to its certification ambitions,  having been designed to be fully compliant with the JAR VLA Part 21 standard – while already holding Germany’s own equivalent, the LTF-UL certificate.

But, will this paper be enough to overcome the higher price – and will the aircraft’s features manage to overcome the lingering stigma of its country of origin – still remains to be seen…

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A soon-to-be familiar sight in ex-Yu skies?

Specifications:

Sila 450C manufacturer specs & detailed info

Manufacturer links:

Other links & sources: