Photo File – The Other U-2: Flying on the Polikarpov Po-2

By me
All photos me too, copyrighted

Back in the summer of 2018, a sudden and quite powerful urge to photograph something really rare and interesting had seen me head for Budaörs Airfield (LHBS) in neighboring Hungary, where I had arranged to fly on the Goldtimer Foundation‘s stunning Rubik R-18c Kánya. An indigenous STOL design created by Rubik Ernő Sr – father of the same Rubik Ernő who would much later go on to design the eponymous cube – it was the last airworthy survivor of just nine made ever, making for a proper, full-on Achtung, Skyhawk! nerdout.

Fast forward to the summer of 2021, and the very same “eastern itch” had returned once again. Deciding, as before, to scratch it while the weather was still fine, I set off for Budaörs once again, intent on getting some air time on another Goldtimer classic, the magnificent and charismatic Polikarpov Po-2 biplane…

Smoke ’em if you ‘got em! To make the whole scene better, there’s a homegrown Rubik R-26 Góbé glider launching in the background, pulled along by 1960s Mercedes-Benz L series winch truck. The only blot on the landscape really is the SR-22…


For an aircraft that would go on to be produced in more than 40,000 examples and achieve so much in both peace and war, the Po-2 had an almost disappointingly straightforward birth. Gotten right straight out of the box, it was designed in 1926 by a young Nikolai Polikarpov (then aged just 34) and intended to be a cheap, simple, no-frills STOL utility aircraft that could be used for anything from basic flight training to crop dusting to reconnaissance and even combat. Flying for the first time on 24 June 1927, it would be designated as the U-2 in the Soviet system of the time (U – uchebnyy, trainer), and would quickly replace the successful but outdated U-1 – itself another Polikarpov design, reverse-engineered from an Avro 504K captured in 1919 during the Russian Civil War. The familiar Po-2 designation would appear only in 1944, and then as a tribute to its designer, who had died from cancer in July of the same year, aged just 52.

An entirely conventional wood-and-fabric affair, the U-2 would be made mostly out of plywood and pine (as common as trees, literally, in the USSR), with key components – such as the engine mounts, wing struts, bits of the cockpit frame and the landing gear – made either out of aluminium in the early versions, or significantly cheaper steel in the later models. Power was provided by the newly developed Shvetsov M-11 five cylinder radial, which produced 125 HP for take-off and 115 continuously in the most commonly used D and K versions – though the 160/140 HP M-11FR was also used on occasion.

However, what the U-2 could do with that power depended entirely on what it was actually meant to be, since each version – and there were many – had its own particular set of masses and speeds. Standard trainers were usually around 650 kg | 1,430 lbs empty and around 1,000 kg | 2,200 lbs at maximum take off mass, which made for a 150 km/h | 81 kts maximum speed, 130 km/h | 70 kts in a realistic cruise, and a ceiling of around 12,500 ft. WW II combat versions on the other hand weighed in at 750 kg | 1,650 lbs empty and up to 1,400 kg | 3,900 lbs full when bombs were carried, which resulted in a top speed of just 130 km/h | 70 kts, a 100 km/h | 54 kts cruise and a drop in ceiling down to some 10,000 ft. Take off performance had suffered as well, with the “heavies” reportedly needing a 50% longer take off run – though this needs to be put into perspective, since the standard trainers took barely 100 m to get airborne.

Despite a slow and pretty chaotic start to production in 1928 – sources quote missing diagrams, mismatching components, inadequate calculations, as well as understaffing and general improvisation at the factory level – the U-2 would find itself in widespread service already by 1930, starting first of all with the USSR’s major flight schools. Unsurprisingly, a number of “early days” issues were found along the way, including leaking fuel systems (w/ inevitable in-flight fires), main gear failures, cracks in parts of the fuselage structure and frequent engine overheating – though many of these would be cured in 1932 with the second production series, which also saw the addition of larger fuel & oil tanks, expanded cockpit equipment and a few extra amenities for the crew. But despite these problems, pilots spoke highly of their vice-free handling, particularly its low speed agility and a degree of longitudinal stability that was unmatched by anything else at the time (which made them highly spin resistant and easy to recover). Post-1932 examples were, however, rated slightly worse in general handling on account of their 20-30 kg | 45-65 lbs increase in empty mass – a not insignificant 5%.

Though there’s ample space laterally in both cockpits, you do tend to stick out vertically if you’re a bit taller. The extent of the Po-2’s simplicity was such that even the Vertical Speed Indicator (VSI) was an option; compared to that, HA-PAO is the decadent Deluxe Model, including posh stuff like Carburetor and Cylinder Head Temperature gauges. The back seat’s a bit more spartan equipment-wise and sports only an altimeter, VSI, Airspeed Indicator, Turn & Bank Indicator and compass

None of this, however, had managed to detract from the type’s enormous potential. During the course of my research for this piece, I’d managed to identify 34 separate versions introduced between 1932 and the end of Soviet production in 1952 – though the realities of flying (and fighting) in the Union inescapably suggest that there may have been many more, undocumented, unaccounted for and nowadays lost to time. Apart from the “bread & butter” training model, the two historically most notable are:

  • U-2AP / Po-2AP: the single-seat agricultural version that gave the type it’s Kukuruzhnik (maize worker) nickname. Produced in more than 9,000 examples, the AP had the front cockpit moved 25 cm forward and a 250 kg hopper installed in place of the rear seat, which could be used either for conventional crop dusting or aerial seeding. Other changes included strengthening the upper wing so it could accommodate a top-mounted fuel tank like the DeHavilland DH-82 Tiger Moth (as there was no longer sufficient space in its usual spot between the engine and cockpit), and moving the rear wing struts slightly to better cope with the new load distribution
  • U-2LSh: the most common combat model, used mostly for nuisance raids on German positions. The standard fixed weapon fit included just a single swiveling 7.62 mm ShKAS gun in the rear cockpit, while up to 120 kg of ordnance could be carried under the lower wing (usually two 50 kg FAB-50 bombs or four RS-82 82mm unguided rockets). The upgraded U-2LNB could carry a combat load of up to 200 kg, and was equipped with aiming spotlights to enable operations even in the dark – while the very similar U-2PTO was more of the same, but adapted to carry napalm canisters and other incendiary mixtures. These two versions would become famous as the main aircraft of the all-female 588th Night Bomber Regiment – the famous Night Witches – who would use them to great effect all the way from the Don Basin in 1942 to the Red Army’s storming of Berlin in 1945. Because of their resulting infamy, Po-2s of all sorts would become known to German troops as the Nähmaschine (sewing machine) due to the very characteristic tapping sound of the M-11 engine

While 1952 would mark the end of official production in the USSR, it would not be the end of the Po-2 itself; indeed, low-key assembly from spares in smaller factories and even by flying clubs would continue all the way until 1959, a full 31 years after its entry into service. What’s more, it would also be made under license in Poland as the CSS-13 (Centralne Studium Samolotów, Central Aircraft Study), initially at the WSK-Mielec plant near Rzeszow (1949-1950) and then the WSK-Okęcie works in Warsaw (1952-1955). Polish sources report that these differed slightly from the originals, sporting different ailerons, an elevator trim tab, upgraded main gear and various minor alterations to the structure; it is also mentioned that these changes had already been included in plans received from Moscow in 1947.

Unlike the originals, the CSS-13 would be produced in only two versions:

  • the stock trainer
  • and the CSS S-13, an air ambulance version with enclosed cockpits for the pilot, medical orderly and a single stretched that was roughly similar to the Union’s own U-2S / Po-2S. A single S-13 would be modified into the CSS-13P, a three-seat passenger model with two seats in the back, similar in concept to the original U-2SP

The actual production figures for the CSS are hard to nail down with precision, since they differ from source to source; but the most credible I’ve seen goes with 550 made in total, 180 at Mielec and 370 at Okęcie. Of the latter, 320 were the basic version and 50 were S-13s – though some sources mention that nine regular models had at some point been converted into ambulances, which would bring the tally up to 311-59.

Nikolai vs Ernő

But, despite its undeniable qualities as an airplane, the Po-2’s postwar association with Hungary came about not because of its capability – but squarely because of politics. At the heart of the matter was the Soviet system of planned economies, whose goal in the early 50s was to assert control over the newly-formed Eastern Bloc, and then use its considerable resources to help rebuild the USSR’s war-torn economy. To do this, emphasis would be put more on heavy industry than consumer goods, which necessitated using the existing infrastructure of the Bloc to its fullest and without regard for long-term consequences. This essentially resulted in each country mass producing only a limited variety of products – usually things they’d been good at before the war – which were then exported for use by both the USSR and the rest of the Bloc. At the same time, high tech and R&D would be consolidated to Russia proper, denying smaller countries the means of potentially outpacing Soviet plans and becoming less dependent and subservient to the Union’s whims.

As far as aviation was concerned, this meant that most of the big, fast stuff – fighters, bombers, heavy transports and airliners – would be designed and produced almost exclusively in the USSR, with satellite states left holding the other end of the market. With their history of large-scale light aircraft manufacture, Poland and Czechoslovakia (and, to a lesser extent, Romania) would take the lead by virtue of having the necessary infrastructure and experience already in place, and thus end up supplying the entire Bloc with training, touring, utility and light transport aircraft, as well as gliders and light utility helicopters. These could be either homegrown – such as the Zlín Z-26 family, and later also the Z-42, PZL-104 Wilga, M-18 Dromader, Let L-13 Blaník, L-200 Morava and the L-410 Turbolet – or in-demand designs from Russian manufacturers such as the Mil Mi-1, and from the 60s onward the Mi-2, Antonov An-2 and Yakovlev Yak-52*.

* indeed, virtually all series production of the Mi-2 and An-2 was undertaken in Poland (by PZL-Świdnik and PZL-Mielec respectively), as was the case with the Yak-52 and Romania’s Fabrica de Avioane Usoare (FCAv) at Bacău

For this system to continue to work to the USSR’s benefit, independent designs from “third countries” would need to be put into a disadvantageous position – particularly if they stood a chance of competing with the superstars – by using the greater output of those big factories to offer better availability, commonality and support. This would also help keep production centralized, controlled and running without interruption to keep up the illusion of progress. The rapid rise of Yugoslavia’s “dissident” aviation industry following the 1948 Tito-Stalin Split – which would eventually go on to design and produce everything from basic trainers to trans-sonic attack jets – was a potent reminder of the “dangers” of letting smaller states flex their potential and use it to slip from under Moscow’s control.

In Hungary, Rubik’s R-18 – which was a more modern aircraft running on the same engine and designed to do pretty much the same things – was thus pushed aside to make way for the Po-2, 20 of which would be acquired in CSS-13 form in 1954, all sourced brand new from Okęcie.

Then & now. Not a big time difference I know, but it is nevertheless good to see they’re both still flying together – especially considering they were at one point market adversaries!

Known sometimes as the CSS-13 Pacsirta (skylark), these would be delivered in two batches – serial numbers 0421-0425 and 0438-0451 – and would initially serve with the Hungarian Home Defense Association (Magyar Honvédelmi Szövetség, MHSz). Modeled on the USSR’s DOSAAF, the MHSz was a volunteer paramilitary organization that used various sporting activities – land, water and air – to train Hungary’s youth in a number of military skills that would come in handy in case of a capitalist invasion (a persistent boogeyman in socialist society). Like many similar organizations elsewhere in the Bloc, it used full-on military markings and nomenclature – so its CSS-13s, used by the air arm for basic training and flying competition, carried military codes based on the last two digits of their serial numbers.

Following the Hungarian Revolution of 1956, they would be handed over to the nation’s flying clubs (minus 22/0422 and 39/0439, lost in accidents), where they would be used for roles as diverse as training, taxi flights, glider towing and occasionally even skydiving. A number would even be converted into agricultural models using the same 250 kg hopper as the Po-2AS, but without its other structural modifications; these would be phased out already in 1960 due to the availability of more efficient machines such as the An-2 – and later the purpose built Zlín Z-37 (flying for the first time in 1963) and even the Kamov Ka-26 helicopter (flying in 1965).

By the mid 60s though, the rest of the 13s were beginning to feel the pressure as well. Having lost two more of their number – HA-PAM/0424 in a crash on 11 January 1959 and HA-PAV/0450 to a fire on the ground on 04 October 1960 – they would also come under attack by fresh designs from Russia and Czechoslovakia (such as the Yak-12A and Z-226) which, while more complex and expensive to run, came handsomely backed by a USSR keen to keep its hand in Hungary’s economy. Couple all of this to the 13s dwindling service hours and the costs of a possible lifetime extension, and the writing was very much on the wall: between 1966 and 1968, the entire fleet would be withdrawn and destroyed on the orders of the MHSz, with only HA-PAU/0443 and HA-PAO/0448 managing to escape the scrap man’s axe…

Life of PAO

Whereas PAU would eventually end up in the Museum of Military Aviation at Szolnok (LHSN) wearing period military colors, PAO would go on to lead a pretty exciting life. Having been used post-1956 as a glider tug at Dunaújváros Airfield (LHDV), it was supposed to be scrapped in 1968 along with the rest of the fleet; however, the airfield managed, Géza Jávor, and the airfield’s chief technician, Ráczkevy Béla, managed to covertly disassemble the aircraft and hide it in a nearby shed, hoping to keep it safe until it could be restored at some future date (this was actually quite a gutsy move in the climate of the time).

That future date would eventually come about in the early 80s, when PAO would finally be taken outside to see the light of day, and trucked some 150 km away to Kaposújlak Air Base (LHKV). There were two reasons for this move: one, it was the home to a major aircraft overhaul center operated by the Ministry of Agriculture’s Aviation Service (Mezőgazdasági és Élelmezésügyi Minisztérium Repülőgép, MEM-RSz) – and two, it was the workplace of Császár Károly, the base commander who had already made his name with restorations of vintage Hungarian wooden gliders, including the Rubik R-07b Vöcsök in 1981 and the Rubik R-11b Cimbora in 1982. With PAO having escaped certain death in such a dramatic fashion – and having been disassembled properly rather than just torn apart – restoring it to airworthy state was a complete no-brainer.

Led by Mr. Császár under the auspices of the MEM-RSz (the formal owner of the aircraft at the time), the restoration was completed in April 1984, just in time for it to be shown to the nation at the May Day parade in Budapest. Though it is nowadays, I believe, the youngest Po-2 in the skies, at the time it was the only airworthy example in the world, and as such was a common sight at airshows not just in Hungary, but further abroad as well; in 1985 it would even make it all the way to Switzerland and back, no mean feat at Po-2 cruising speeds!

It was at one such event – the Budaörs Airshow of 06 June 1986 – that Mr. Császár would, sadly, suffer a fatal heart attack near the end of his display routine. Having apparently already been trimmed for landing, PAO had managed to get down on its own near the western edge of the field, overrunning the airfield boundary and coming to a stop in what, at the time, was a small swamp. The Po-2’s low landing speed precluded serious damage, with just the main wheels and legs sheared off. Not long after Mr. Császár’s funeral, PAO would be airlifted out of the swamp by a Hungarian Air Force Mi-8 and quickly returned to airworthy condition.

Shadows of the past. PAO’s suitably loud tribute to both Mr. Császár and itself as we overfly what was once the very swamp it ended its flight in 35 years ago…

From that point onward, PAO would finally settle into a routine of well deserved stability, continuing (with a break or two) to run pleasure flights and impress crowds at airshows to this day. Indeed, the only significant post-1986 event was the end of socialism in Hungary and the subsequent dissolution of the state-run MEM-RSz in 1989. Now in need of a new home, PAO and HA-RUF – the R-18 that had started this entry – would soon pass to the Museum of Transportation in Budapest, which would then loan them long term to the Goldtimer Foundation following its formation in 1992.

This was, thus, the situation that greeted my when I arrived at Budaörs on a beautiful September afternoon, hungry for more noise and vibration than the Q400 could provide… 😀

Closing in on a soaring Scheibe Falke like a real WW I pursuit crew. That (deafening) noise… those vibrations… the wind… the smell of burning petrol… the droplets of oil flying backwards out of the exhaust… but most of all, all that sky… after 20 years in light aircraft, I still can’t remember when I’ve had so much fun in a (mostly) straight line!

When the Po-2 was first thrown into combat on the Eastern Front, opposing German pilots soon discovered that the minimum speeds of the Bf.109 and FW.190 (particularly the later, heavier versions) exceeded the maximum speed of a fully-laden Po-2. We had no such problems, however, in keeping up with the Falke, since we could both comfortably maintain just 80 km/h | 43 knots

Dat air space. Normally when I fly the C172 or the Falke, I have the devil’s own time trying to get a clean shot through the open window or vent panels in the canopy; on the Po-2, that’s not really an issue! Looking back at Budaörs (and Budapest city in the distance) as we leave the pattern for some low level work. The sheer openness of the rear cockpit (the frame is actually below my shoulder blades) and just a basic period harness keeping you inside it not everyone’s cup of tea – hence the rear stick being removed to prevent passenger clutching to it during maneuvers

Low, slow & loud. True to its character, the highest speed I’ve seen the entire flight was just 145 km/h | 78 kts – and even that only in a shallow dive

With the “most open” thing I’ve flown being a Super Cub with the door down, I was naturally keen to see what would be the comfort level on an open-cockpit biplane. To my surprise, it was not the airflow as such, even though the windscreen provides only meager protection – it was the propwash, which spiraled around the airframe in such a manner that it was felt particularly strongly on the left side of the rear cockpit. Combined with that tappety five cylinder radial, life in the back was not really comfortable at full throttle noise- and wind-wise, and I was glad for the long sleeve shirt I’d brought along, despite it being a very agreeable 26 degrees Centigrade at altitude

Just a Kukuruzhnik doing Kukuruzhnik stuff…

Some old school “I Follow Roads” navigation with Mr. Krauth Peter, whose career at the now-defunct Hungarian state airline MALÉV spanned almost 30 years. Seven decades worth of biplane, my first open cockpit flying experience, beautiful weather – and an fellow airliner driver to chew the fat with on the ground… can’t beat that for a Saturday afternoon out!

As always, I would like to extend my sincerest thanks to Goldtimer Foundation members Mr. Krauth Peter and Mr. Janos Zoltán – the former for a fantastic flight, and the latter for sharing so much about PAO’s history!


Photo File – Contrafun: Flying On The Kamov Ka-26

By me
All photos me too, copyrighted

Even though I’ve been a fixed wing driver from Day One (private and training helicopters being so rare in Croatia), I’ve nevertheless always maintained a fancy for all things rotary. Indeed, my first ever flight – back when I was just a toddler – had been on a Yugoslav Air Force Mi-8, followed up later in adulthood with hops on the Bell 429 demonstrator, and with Red Bull’s own Rainer Wilke on the fully aerobatic Bo-105 (an experience I’m not likely to forget!). From then on however, my contact with the helicopter world had been reduced to being on the working end of the camera viewfinder – a situation that would dramatically change for the better in the summer of 2019 🙂 .

Having been aware of my long-standing desire to photograph a piston engine Kamov up close, a friend from neighboring Hungary – himself an avid helicopter spotter – had managed to do me one better, arranging not only a “free hand” photo session… but also a short semi-aerobatic flight. The only string attached was that I get my arse to Budapest on my own accord – a condition I was more than happy to accept! 😀

It may be the textbook definition of the world “fugly” – but on that day it was the most beautiful helo in the world!

The HA Ka

The rather colorful bird that would be my ride for the day goes under the name HA-MPB, and sports the serial 77 061 09 – a typical Soviet sausage that tells you (almost) everything you need to know:

  • 77 … manufactured in 1977
  • 061 … as part the 61st batch made (out of 65 in total)
  • 09 … and the ninth example in the batch

This puts it among the youngest examples of the 848 made in total between 1969 and 1978 – and one of at least 149 that would eventually serve in Hungary (either straight from the factory, or through resales). Unlike the vast majority of its brethren however, MPB is still very much active, and spends most of its uptime dusting crops up and down the country. Indeed, on this day it had popped into Budaörs Airfield (LHBS, not a stranger to me) solely to participate in the upcoming Budaörs Airshow, following which it would quickly depart back into the southern fields and resume normal operations 🙂 .

While my roster at work had prevented me from staying the show’s full three days, I had nevertheless had ample time to pour over MPB in much detail. Though many of the design’s finer nuances will inevitably be lost on me – Fixed Wing Guy, remember* – there is nevertheless still enough eye candy here to arouse the interest of even the most basic aviation enthusiast!

* any corrections from whirlybird drivers would be most welcome!

Getting ready for the day’s practice run with a lick of paint and a thorough wash. Despite the performance penalties of the extra weight, MPB would fly its routine in full crop spraying kit…

In addition to their distinctive main spray bars, many Ka-26s feature a secondary unit slung from the horizontal stabilizer. Specs I found online indicate that with all three in operation, the average 26 could dispense up to 12 liters of fluid per minute (though dispersion system upgrades in 1978 and 1979 would improve on that by a couple of liters/minute)

In the crop dusting configuration, the hopper can accommodate up to 900 kg of fluid. A neat trick is that it’s actually part of a removable payload module that can be easily taken out in the field, and replaced with the minimum of specialized tools by a selection of other factory-made modules (passenger, ambulance, freight platform, sling hook, …)

Not your usual view! Despite its unwieldy look and apparent bulk, from the top it is obvious that the Ka-26 is actually quite compact, sporting the minimum amount of structure necessary to bring together the engines, cabin, rotor system and payload module. There blades themselves are actually composite and very light, and feature substantial leading edge protection at their tips – all of which gives them a solid 5000 hour service life, even in the rough-and-tough going at low altitude

The party piece of (almost) every Kamov design: the counter-rotating coaxial main rotor. Though mechanically more complex than the conventional arrangement, this setup allows for greatly increased efficiency, since the blade area – which produces the lift – is now doubled, and there are no mechanical and friction losses inherent to the tail rotor and its transmission system (which also does wonders during autorotation). Another benefit – epitomized by the Ka-50/52 gunships – is a very high degree of maneuverability in all axes, as well as a much more neutral mass distribution that does wonders for hover characteristics, general handling and overall agility

Arretir! Drawing heavily upon Kamov’s naval experience, the Ka-26 could be equipped with a full IFR panel and some pretty sophisticated kit for its class – stuff that didn’t always sit well with operators, since it tended to add complexity and increased maintenance costs. Many examples (especially those used at very low altitude) would be stripped down in actual operations; MPB however had retained most of its factory setup, minus the blind flying gear

Having spent the majority of its life in Hungary, MPB sports a typically curious mix of Russian and Hungarian dials, which do add a lot of charm to the cockpit…

Being one of the very few (maybe even only) production light helicopter with TWO piston engines, the Ka-26 does sport a lot of powerplant-related switches and knobs – so much so that it seems you need three arms to successfully start it first time out…

More traces of the Ka-26’s Soviet design heritage: the single primer pump in the middle (which is turned into the direction of the desired engine before being actuated), and the air system valve w/ pressure gauge, which provides the juice for the main wheel brakes (a common solution on Soviet aircraft to avoid the weight penalties and poor cold weather performance of conventional hydraulics)

Another icon of Soviet general aviation: the venerable and dependable M-14 nine cylinder radial, here in its V-26 version developing 325 HP. To tackle the unique aspects of helicopter flight – high RPM, high throttle and low (or no) forward airspeed, the fit on the Ka-26 features powerful cooling fans (visible behind the fully opened cowl flaps), which force air over the cylinders to keep them sufficiently cool regardless of flight regime. They also make a LOT of noise!

Two big Soviet radials, two huge coaxial rotors, a traditional cockpit fan – and a semi-aerobatic duet with a 1950s Hiller UH-12… yep, didn’t mind the four hour drive one way!

One a pristine vintage “oldtimer”, the other a no-nonsense everyday working machine… one conventional on Lycoming power, the other coaxial with twin radials… one user-friendly Western, the other utilitarian Eastern… fun is guaranteed! Another interesting feature of the Ka-26 – negated here by the open door – is that the cabin is actually pressurized to slightly above ambient, to prevent spray and chemicals getting in during crop dusting ops

And finally, a bit of video from the inside… admittedly, not the best quality (the lighting was marginal all throughout the day), but hopefully the action will make up for it! Also not the piercing turbine-like noise in both clips; those are the aforementioned cooling fans spinning their heads off 😀 .

Bonus content: Hiller UH-12D • HA-MIG

Drooling all over the Ka-26 is fine and well – but when you get to fly in a duet with a vintage Hiller, you should at least try to make an effort to snap it as well! 😀 Returning back to the apron after our run, I was lucky enough to stumble upon said helicopter and its owner, who kindly allowed me to snoop around and bit and soak up the beauty of one of the world’s earliest mass produced light helicopters…

Halfway through a thorough wash following its practice display. Manufactured in 1959 with the serial 1145, MIG would serve first with the US Army as 58-5496, before going civilian as N67664 and N16MQ. Sold to Hungary in 1997 (as one of a number of UH-12s coming into the country during the 90s), it would eventually end up in the hands of Fly-Coop, one of the largest aircraft operators of the Budapest area. Note the exposed tail rotor transmission atop the tail boom

Though the type normally sports the six cylinder Lycoming VO-435 developing 265 HP, this particular machine had at one point been retrofitted with the more powerful Lycoming VO-540, developing a chunky 305 HP (it showed during the display!). Of note is the engine V prefix, which stands for “vertical” – denoting the modifications for the only possible way of installing it into a light helicopter

A panel that can easily provoke traumas in anyone who had flown a 1960s Cessna – no rhyme or reason in the layout, and made by someone who studied economics, not ergonomics. That notwithstanding, surely a cool place to sit!

Traditionally, I would like to extend my sincerest thanks to all the people – ground and air crews alike – that had made this photo shoot possible, particularly Gergely C.!


Photo File – Rubik’s Tube: Rubik R-18c Kanya, HA-RUF

By me
All photos as credited

I’ve always said that only good things can happen when you use your off time from flying airplanes to – photograph airplanes. For me, this was very much the case recently when my itchy photo finger led me into neighboring Hungary in search of interesting indigenous and Eastern Block flying machinery. And while almost every airfield there is a gold mine in one way or another, my travels that day had taken me straight to Budaörs Airfield (LHBS) just outside Budapest, a well-known GA center in its own right – but doubly more interesting as the home of the Goldtimer Foundation. An eclectic group of enthusiast dedicated to preserving the country’s rich aviation heritage, it is most famous for its flagship, the world’s sole airworthy Lisunov Li-2 – a Soviet license built version of the early C-47 that had needed so many alternations (1400+ by some counts) to survive life in the Union that it pretty much became a standalone type.

But while the Big Li has always been the foundation’s party piece, the rest of its six-strong fleet also boasts much to write home about – in particular my target for the day, the home-grown (and extremely rare) Rubik R-18c Kánya STOL utility aircraft… 🙂

Rarity: check. STOL credentials: check. Russian radial: check. Yellow paint: check. Everything’s here!

Last of the Mohicans

While it may lack the pedigree and heritage of similar designs East or West, the R-18 nevertheless ticks many Achtung, Skyhawk! boxes right from the start – not least of all for its interesting origins. Designed in 1944, the R-18 was penned by Ernő Rubik (father of the same Ernő Rubik who would much later design the eponymous cube) and was intended to fill the niche for a cheap-and-cheerful STOL utility aircraft that could also double as an effective glider tug. Despite nowadays being known solely due to Junior’s successes, Rubik Senior was at the time already a prolific aircraft designer*, and was thus intimately familiar with the challenges of producing a rugged and dependable working aircraft on a tight budget. Though the R-18 was never a direct copy (being much smaller for starters), to make it work Rubik had from the outset used the superlative Fieseler Fi-156 Storch as inspiration, adopting its solutions such as large fixed slots along the wing leading edge, wide-span drooping ailerons, a mixed wood/metal construction to save on strategic materials – and a tall landing gear that could both cope with the realities of rough field operations and provide sufficient drag to allow for steep approaches. Unlike its idol however, the R-18 would not have folding wings, a powerful engine with a constant speed propeller, provisions for light armament or quite the same insane level of STOL performance – all compromises made to simplify design and construction and keep production costs manageable.

* what’s more, Rubik Sr. would continue at it even after the war, turning his attention now to gliders (on which he had actually made his name before the war). The most successful of these new designs was the R-26 Góbé of 1961, a simple all-metal two-seater with a moderate 14 meter wingspan. Though production had ended in the late 60s after 115 examples were made, the design would come back to favor again in the late 80s, when a modernized version – the R-26SU Góbé 82 – was put into production by a Hungarian automobile plant. Despite this unorthodox return and the availability of the Let L-13 Blanik, a further 78 examples would be completed and sold, a large proportion of which continue to happily fly to this day.

In spite of its down-to-earth design goals, the R-18 – now named Kánya (“kite”, a species of hawk) – would not see the light of day until the end of the war. The German occupation in May of 1944 and the arrival of the Red Army in September had had a catastrophic effect on the country’s aviation industry, which made producing even such a simple and basic no-frills aircraft a very tall order indeed. In the event, the first Kánya – the R-18a, carrying the serial E-524** and military ID 1-002 – would be completed only in 1948, flying for the first time on 18 May 1949.

** like many Hungarian light aircraft, the R-18 family was produced by the state-owned Sportáru Termelő Nemzeti Vállalatnál aircraft factory at Esztergom (now LHEM) in northern Hungary. This was reflected in their serials: E-524 may sound exotic, but it simply meant 1-002 was the 524th aircraft produced at Esztergom so far.

The very first R-18, showing the original cabin shape and doors (photo from:

In its original guise, the R-18a was a pretty clean three-seater (two in the front, one in the back), powered by a Czechoslovak Walter Major 4-I engine which developed a modest 130 HP from four inline cylinders, and spun an unremarkable two-blade fixed pitch propeller. Interestingly, Rubik had envisioned the Kánya to be powered by a British-made inline engine (such as the 135-150 HP Blackburn Cirrus Major), but the post-war political situation in Hungary had quickly sent that idea down the tubes.

Originally pitched to the reformed Hungarian Air Force, 1-002 would quickly be made redundant by large numbers of readily available aircraft coming from the USSR (most notably the Polikarpov Po-2), which left Rubik with only one option – to go civilian. To this end, 1-002 would be transferred to the civil register, becoming HA-RUA the same year. Unfortunately, not long afterwards it would be involved in the type’s very first accident, when it stalled at low altitude and sideslipped into the ground during a glider tow demonstration. Even though the damage was repairable, the aircraft was not rebuilt and was instead re-purposed as a training aid for apprentice mechanics.

Based on experiences from military test flights and civilian trials, Rubik then developed the slightly improved R-18b, whose primary claim to fame was a redesigned fuselage around the rear seat, allowing the second passenger a bit more breathing room. As was the case with the A, only one B model would be made, wearing the serial E-552 and registered HA-RUB. Like its predecessor, it would meet its end during a glider tow exercise on 25 September 1954, ending up severely damaged in a corn field after running out of fuel.

Mostly identical to the A model from the outside, the B could only be recognized by slightly different contours of the fuselage just aft of the wing (photo from:

Having been convinced all along that there was more to come out of the basic design, at the very beginning of the 50s Rubik began work on a more extensive update, which would debut in 1952 as the R-18c. Compared to the B model, the C – in the form of the “prototype” HA-RUC (s/n E-761) – packed a more powerful six cylinder Walter Minor 6-III developing 160 HP, as well as a cut down and extensively glazed rear fuselage. The new powerplant was initially delivered with a two-blade Avia V410 variable pitch metal propeller – but unspecified problems with its reliability had quickly seen the switch back to a classic fixed pitch wooden unit manufactured right at Esztergom. Having caught some flak due to comfort issues with the A and B models’ rear seat, Rubik would soon dump it completely and replace it with a 120 l fuel tank to augment the two standard 60 l tanks located in each wing root.

In this tweaked form – which one source calls R-18c/1 – the C would become the first, and last, R-18 to enter any form of series production, with just six further examples completed between 1952 and 1953 (registered HA-RUD through HA-RUI). The reasons for such a short production run vary from one source to the other; but staff at Budaörs had told me that the R-18 was simply a casualty of Eastern Block politics of the time, which prioritized the import of aircraft from large factories abroad over small-scale indigenous production. Thus, like the original A model, the Kánya as a whole was simply swept away by a tidal wave of Polikarpovs, Yakovlevs and Zlins rolling in in their hundreds.

Visually the most curious of the lot, the C model can be identified by the long nose, large cowl flaps on the right side (not visible here) and the cut-down rear fuselage. Other changes included larger doors, which significantly improved the view downwards (photo from:

To add insult to injury, the Minor engines would prove to be quite problematic and failure prone in Hungarian service, leading to a disproportionate number of incidents and write-offs; indeed, some sources claim that by 1966 – when the type was withdrawn from service – only two aircraft had remained intact. This rate of attrition had between 1955 and 1958 prompted a fleet-wide re-engine program, in which the Minor was thrown out in favor of the Shvetsov M-11 five cylinder radial used on the Po-2 (and manufactured by WSK-Kalisz in Poland), developing either 125 HP in the D model – or a more substantial 160 HP in the FR variant. Unlike the home-grown props used with the Minor, both M-11 variants would be bundled with the “factory default” WD-450, also made by WSK.

Interestingly, there was only one other structural mod attempted – and that was fitting skis to HA-RUE (s/n E-763). The aircraft was subsequently based at Budaörs, but I had been unable to find any photos of it in this configuration.

Kite flying

One of the two lucky ones to survive into their old age, the foundation’s example goes by the name HA-RUF, and was the first Kánya to be produced in 1953 (wearing the serial E-778). A standard R-18c (or R-18c/1 according to some), it sports the more powerful M-11FR engine, and had flown for the first time (again) on 1 October 2012, following an on-off restoration that took more than 20 years. Painted in accurate period colors that really make it stand out on the apron, it would immediately after enter the Goldtimer fleet, where it would happily open its doors to wandering aircraft geeks… 😀

While it is far from flattering, a head on view of the R-18 best shows its “Inspired by Storch” design. As well as providing adequate shock absorption, the tall main gear also ensures ample propeller ground clearance. However, the entire gear system is at the same time one of the Kánya’s biggest weak spots: fractures of the main gear attachment points have been reported throughout its service life – and the freely castoring tailwheel, coupled with the soft suspension, means that ending up in a nasty ground loop doesn’t require much effort

Though it lacks the visceral appeal of a big radial, the M-11 is nevertheless a perfectly charming little package in its own right. The exposed valve rods, a tendency to spit oil out of the exhaust, inevitable misfires on idle and that famous “sewing machine” sound all make for a delightful experience

A notable leitmotif of the R-18 is simplicity – and the use of whatever components the production team could get their hands on. The oil and rear fuel tank fillers (left and right respectively) have, for example, been salvaged from wartime German aircraft and take some getting used to – particularly for those of us brought up on the “plug & play” systems used on Cessnas and Pipers. Of further interest, the nose and cabin are the only bits of the Kánya that are made of metal; the rear fuselage, tail and wings are all wood (+ a bit of fabric)

In common with many aircraft from the Soviet sphere of influence, the R-18 uses pneumatics, rather than hydraulics, in its braking system. The upsides are a low total system weight and carefree operation in cold weather – but at the cost of very coarse metering and the need to isolate the air tank from the installation when the aircraft is at rest to prevent leaks. On the R-18, the valve for the tank is located on the floor in front of the seats – a pretty convenient solution compared to some others I’ve seen

As on any self-respecting utility aircraft, the visibility out of the cockpit is excellent in pretty much every direction, and there’s extensive glazing everywhere but on the floor. Apart from the sheer amount of air and light, I was most fascinated by the clean panel layout, which is ergonomic far beyond its 40s origins. Inevitably (and thankfully) there still are a couple of oddities: the comm radio is BELOW the pilots seat (barely visible here), the flap position indicator is above the pilot’s head – and the fuel level indicators for both wing tanks are combined into a single tube-style gauge above the passenger door. Another curiosity are the instruments, a charming mix of German, Soviet and Hungarian gauges and switches

Despite the Kánya’s high stance, visibility over the nose is excellent, which allows for easy operation on the ground (steering by differential braking notwithstanding). An interesting detail is the vertical rod nearest the door: this is actually part of the flight control linkage and actuates the ailerons. Unlike most modern light aircraft, the R-18 uses pushrods for all flight controls, which – while adding weight – give it a very quick, precise and predictable feel. The flaps too are mechanical and are operated by a Piper-like handle between the seats

An unusual view backwards showing just how much the C model’s cut down fuselage helps with visibility. Naturally, with all this glazing the cockpit can get pretty hot on sunny days, even with the roof-mounted sliding curtain drawn all the way. An interesting peculiarity here are the yellow tubes, which actually form part of the C’s fuel system. Unlike on the A and B, fuel from the wing tanks drains first into the fuselage tank, from where it is then drawn into the engine

The proper way to spend a vacation: buckled up in a German WW2 harness, pulled along by a Russian sewing machine, valves tapping away in front of your eyes and a windscreen full of oil drops from the exhaust…

The world’s sole airworthy R-18 to the background of the world’s sole airworthy Li-2… I kind of like it here I must admit!

And finally, a bit of video… a poor attempt I admit, but I’m not one with moving pictures and the air that day was a bit turbulent. But you can still hear the Singer in the nose doing its thing – and that’s worth a thousand pro videos! 😀

Customarily, I would like to thank everyone at the Goldtimer Foundation for a beautiful flight, especially my pilot, Mr. Gabor Szakacs!

Appendix – R-18 production list:










crashed 1949 (location unknown)





crashed 1954 near Székesfehérvár





crashed 1962 near Gödöllő





crashed 1956 near Szentes





fitted with skis; wfu 1966 and scrapped





wfu 1966; made airworthy in 2012





wfu 1966; in a museum until 2016





crashed 1957 near Kaposvár





wfu 1966 and scrapped

* HA-RUG was the sole surviving Minor-engined example; was displayed in a museum in Budapest until 2016, can’t find trace of it afterwards