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As I had already noted in a previous post, the world of social media – while often tenuous – can on occasion also be a fantastic (and nearly inexhaustible) source of inspiration and information on pretty much any topic conceivable. Having already been responsible for two of my historic articles to date, Facebook (for one) must take the plaudits for #3 as well, having led me (by a roundabout way) to probably one of the most interesting aeronautical projects in the region :).

While browsing a local aviation group one day, I chanced to stumble upon an unusual photo of a partially-disassembled North American F-86 Sabre wearing the tell-tale colors of the Yugoslav Air Force. Instantly intrigued, I’d started digging a bit deeper, eventually finding out that it is actually an in-progress restoration job going on next door in neighboring Slovenia. Naturally enough, it did not take me long to find and bother the people responsible, eventually managing to set my sights (and viewfinder) for the towns of Kranj and Pivka in the hilly west of the country…

Boran in Wonderland

While it cannot match the scale (nor financial backing) of similar endeavors further out west, this project is nevertheless a sight for sore eyes, and represents one of the most detailed aviation preservation works undertaken since the fall of Yugoslavia. Headed in the hands-on department by Mr. Alojz Potočnik, the Sabre’s restoration is actually part of a much larger museum drive jointly led by several notable Slovene institutions, including:

the Pivka Park of Military History (Park vojaške zgodovine Pivka), which has been given long-term use of the aircraft and will display it in its own collection

(Park vojaške zgodovine Pivka), which has been given long-term use of the aircraft and will display it in its own collection the Slovenian Army Military Museum (Vojaški muzej Slovenske vojske), which is formally the owner of the aircraft and whose custodian – Mr. Matjaž Ravbar – is responsible for the historical and technical accuracy of the restoration

(Vojaški muzej Slovenske vojske), which is formally the owner of the aircraft and whose custodian – – is responsible for the historical and technical accuracy of the restoration the Slovenian Army (Slovenska vojska), which has provided some of the workforce for the restoration work

(Slovenska vojska), which has provided some of the workforce for the restoration work and the Pivka Municipality, which has – in this instance – fronted part of the restoration costs, with the rest having been made up from various EU funds

Though the Sabre was the one item that had initially caught my eye, the project also includes the preservation and display of several other aircraft that had previously flown with the Yugoslav Air Force – or had played their part in the defense of Slovenia during Yugoslavia’s violent dissolution in 1991. Numbering at four machines so far – two already displayed and two (the Sabre included) still in the works – this project is well on its way to becoming one of the highest-quality aeronautical collections in the region, and is already beginning to draw in an ever increasing number of visitors – some even from well outside the former borders of Yugoslavia. One of these, however, had decided to askew the normal tour program, electing instead to start straight at the source: the workshop of Mr. Potočnik :D.

The place where a number of the Park’s non-winged exhibits also came from, it was on this day home to two aircraft which, on the face of it, should not really rate all that high on the rarity list: the West’s most produced jet fighter – the Sabre – and the world’s most produced fighter, the MiG-21 :). Standing at 9,680 and 10,645 examples produced respectively (excluding Chinese-built versions for the latter), both are still present in significant numbers on the airshow circuit, with the -21 still clinging on in front-line service even with several air forces in the European Union*.

* Bulgaria, Croatia and Romania to name them. While the type is also in use in Serbia, it has been relegated to secondary roles and exists today in small numbers only.

However, the actual machines present here were of a different class altogether, representing first the exceedingly rare IF-86D – a Yugoslav home-brewed reconnaissance version of the “big Sabre” – and then the MiG-21F-13, the type’s first ever operational variant. In various stages of restoration (with the MiG significantly closer to completion), they had both promised to provide fantastic insight into the restoration process – as well as allow me to sneak a peek at some of their inner workings… 🙂

1. North American IF-86D-41-NA Sabre, 14325

Even though it shares the name, designation and general stature of one of the West’s most prominent fighters, the first machine to be featured here is actually somewhat of a black sheep within the extended Sabre family tree. Longer, wider, heavier and faster than all of the originals, the D model – often called the Sabre Dog – is in reality a separate type altogether, owing only its basic configuration (and various other bits of DNA) to the stock F-86…

Originally intended to be called the F-95, the D model can trace its roots back to the end of the 40s and attempts to turn the day-only Sabre into an advanced, all-weather fighter that could cope with the masses of Soviet bombers anticipated to eventually head for US borders. Faced with the need to carry both advanced weaponry and a bulky early-gen radar – AND then get both up to intercept altitude in a reasonable period of time – the new aircraft had immediately warranted a significantly more powerful engine, as well as a modified fuselage to accommodate the lot. Dispensing with the 23 kN General Electric J47-GE-13 of the later A models, the D would solve the first problem by being fitted with a reheated version of the same engine – the 33 kN J47-GE-17, later replaced by the 34 kN -33 – whose long reheat system and exhaust pipe had necessitated a one-meter fuselage stretch.

Its intended task as a bomber hunter had also brought about a rethink of its armament solutions. Rather than rely on old-fashioned guns – which were considered to be ineffective against dense, clumped masses of heavy aircraft – the Sabre Dog was to be armed with 24 70-mm “Mighty Mouse” Folding Fin Aerial Rockets (FFARs), housed in an unique retractable tray located on the underside of the fuselage. Wide by necessity – in order to accommodate the largest number of rockets possible without being too tall – the tray too had come to define some of the dimensions of the fuselage, being responsible for a small (but nevertheless noticeable) increase in the D model’s girth :).

In order to be able to find the bombers it would fire its mice at, the Sabre Dog was also fitted with an AN/APG-36 search radar, housed in a distinctive radome on the upper lip of the intake. With an effective range of some 55 km (30 NM), the radar was slaved to an (at the time) advanced fire-control system, allowing the aircraft to zoom in behind an enemy formation, discharge its rockets in a pattern calculated to inflict the maximum amount of damage – and then zoom out while still remaining (more or less) outside the presumed range of the formation’s defensive guns.

But, while all of this may sound solid in theory, in practice the aircraft had suffered from a number of serious shortcomings – all of which were a consequence of its transformation into something the original Sabre was never designed to be. The Mighty Mouse system, for example, was shown during tests to be inaccurate and ineffective; the aircraft’s sheer bulk had required a high landing speed and, by association, a long runway; the J47’s add-on reheat system was prone to malfunction – and the aircraft was generally too complex to handle by the average single pilot. All of this had, in fact, earned it the unflattering nickname Sabre Dog – alluding more to it being an under-performing “dog” than a separate model of the F-86 :).

Nevertheless, between 1957 and 1961, the F-86D would be one of the mainstays of the US’ aerial defenses, until being supplanted and eventually replaced both by new aircraft types and upgraded versions of itself (most notably the much-improved F-86L). Its withdrawal from service had immediately led to a strong export drive, intended partly to recuperate as many of the funds invested into its acquisition as possible – but mostly to help shore up Europe’s WW2-battered defenses against the threat of the USSR**.

** following the formation of NATO as a functioning force, the US had instantly sought to strengthen the edges of Western Europe – and create a protective buffer for itself along the way – should the Union’s sabre rattling suddenly become less benign. Still not having caught their industrial breath following the ravages of WW2, countries such as Italy and West Germany were thought to be particularly vulnerable, leading to the decision to sell them – often for next to nothing – both surplus hardware from the war, and newer metal that could achieve a measure of parity with whatever the USSR could throw at them. Known as the Mutual Defense Assistance Program – MDAP – this project would eventually be responsible for most of the US machinery operated by West European forces throughout the 60s and early 70s.

Even though it was somewhat on the wrong side of world politics, one of the type’s customers was also Yugoslavia, at the time looking to modernize its leftover WW2 fighter and ground attack forces (then made up of an eclectic mix of local, US, British, German, Italian and Russian machinery). Even though the 1961 sale of 130 examples (comprising 36, 41, 45 and 50 series jets) to a communist country had caused a bit of an uproar at home, the US government was nevertheless quite forthcoming, especially since Yugoslavia had already operated the Lockheed T-33, Republic F-84 and Canadair-built “straight” Sabres – all important bits in trying to lure the country (which has always been non-aligned) to its side of the Iron Curtain.

While all of these jets would go on to lead variously interesting lives – some having already been earmarked for cannibalization on arrival – the ones of special interest to us were the 32 examples intended for conversion into home-grown photo reconnaissance platforms :). Done by the Jastreb (goshawk) works of Zemun, Serbia, this modification had quickly become known as the IF-86D (I – izviđač, scout), and had entailed the replacement of the Mighty Mouse system and its tray with a custom fit of three Kodak K-24 downward-facing cameras***, as well as the addition of wing mounting points for target illuminating flash bombs. Apart from this, the jets would remain the same in all other aspects in order to keep maintenance costs down to a minimum.

*** interestingly, the Sabre Dogs would not be the only machines to receive this treatment. Another notable type to be modified so was the TV-2, designated as the ITV-2 and IT-33 in service.

However, how and where 14325 fits among them is still subject to some confusion, since the machine’s true identity and lineage have not yet been conclusively established. Upon their arrival into the YuAF inventory, all 130 jets had been allocated codes in the 14001 to 14130 range; however, one modified into the IF-86 standard, the 32 jets selected were re-coded as 14301 through 14332. While the serials for all 130 are available through public channels, they are referenced only to the original codes, and are not correlated with the IF “re-branding” – making even the Park and Museum unaware of 14325’s full and complete history. The level of uncertainty is such that in some channels the aircraft was rumored to actually be 14307 – though this had been disproved by the Museum.

Whatever its case, a helpful fact is that all of the recce Sabres had stuck together their entire lives, flying first with the 184th Reconnaissance Aviation Regiment from 1963, and then with the 352nd Reconnaissance Aviation Squadron when the former disbanded in February 1966 – both of which had been based at my home airport, Zagreb (ZAG/LDZA) :). Interestingly, the IF would have relatively short service lives, having been withdrawn from use already in 1967, formally struck of the active inventory list in 1968 – and then replaced by MiG-21Rs when the squadron moved to Željava Airbase on the border of Bosnia and Croatia****. As was the case with other types being pulled completely from service, several IF-86s had soon ended up as gate-guards across former Yugoslavia, with 14325 being posted at Ljubljana’s Brnik Airport (LJU/LJLJ). Interestingly, once displayed, it would be given the code 14146, a fictitious out-of-sequence identity never used in actual service.

**** an interesting side-story is that the squadron, its aircraft and new base would later go on to play an important part in modern Croatian history. On 25 October 1991, (then) captain 1st class Rudolf Perešin would fly the squadron’s MiG-21R 26112 to Klagenfurt, Austria during a reconnaissance sweep of Slovenia, becoming the first Croatian pilot to defect from the YuAF during the 90s civil war.

It would then stay at Brnik for the better part of 40 years, being forced to endure the fate of nearly all non-museum aircraft in the region – a slow death by atmospheric wear and sheer neglect. By the time it had been taken under Mr. Potočnik’s wing in 2014, 14325 had suffered extensive corrosion to parts of its structure, a tear in the lower aft fuselage – and the attentions of local scavengers and scrap-metal dealers. Thankfully though, all of the damage was deemed repairable (albeit with a lot of work!), making the aircraft an ideal candidate for restoration and display at the Park… 🙂

2. Aero S-106, 22542

The second aircraft present in the shop though was perhaps even the more attractive one – if anything for the visceral appeal of the MiG-21 shape to a person used to seeing it his entire life :). Looking like it had just rolled off the production line, its sleek curves accentuated by the bare-metal finish, 22542 will eventually become one of only two early -21s displayed in the lands of former Yugoslavia – and one of the preciously few F-13s of any sort to be found in this part of Europe…

However, while it may look, smell and feel like a genuine YuAF example, 22542 is in reality a former Czechoslovak machine – which actually makes it an S-106, a MiG-21F-13 produced under license by the Aero Vodochody works near Prague (makers of the superb L-39 Albatros trainer) :). Having never had anything to do with Yugoslavia throughout its service life, now-22542 was manufactured in 1965 with the serial 560313, becoming 0313 when delivered to the Czechoslovak AF on 6 December of the same year.

Destined to spend its entire flying career on training duties, 0313 was first allocated to the Air Force Training Center at Přerov Airbase (PRV/LKPO), from which it would be transferred to the 1st Training Regiment (based at the same base) upon the latter’s formation in September 1973. Second in longevity only to Albania’s Chengdu-manufactured F-7s, 0313 and its squadron mates would eventually go on to become some of the oldest F-13s still flying in Europe, with 0313 itself struck off the military registry only on 19 June 1990 – and with just shy of 1,393 hours on the clock. Shortly afterwards – on 17 July to be precise – it would be transferred to the military aviation museum at Prague’s Kbely Airport (LKKB), where it would remain until acquired by the Military Museum in 2011 and picked up by Mr. Potočnik in 2014.

While the original intent had always been to restore an authentic Yugoslav machine, the inability to acquire one had forced the restoration team to think laterally and look elsewhere for a replacement. However, while they now had an aircraft to paint, its lack of a “Yugoslav pedigree” had meant that giving it an actual YuAF code would have been stretching history and accuracy to their limits – leading to the decision to simply give it a fictitious identity :).

The task of choosing this new ID was – interestingly – pretty straightforward. Known in service as the L-12 (L – lovac, hunter), the YuAF had operated a total of 41 F-13s, all delivered between 1962 and 1966 – and designated 22501 through 22541. Slotting itself nicely into the sequence without causing too much historical disruption, the new addition was simply christened 22542 :). Near completion at the time of writing, the aircraft will soon join the Park’s collection, and be displayed alongside the Sabre and two other machines in a new, purpose-built museum hall.

A Walk in The Park

But, to fully appreciate just where these two restorations are going – and how much effort will yet be put into their work – one also needs to see and admire some of the “finished products” :). As mentioned in the opening entry, two completed machines – restored during an earlier phase and financed by the Army – are already displayed at the Pivka, and kept under the watchful eye of the Park’s expert associate, Mr. Boštjan Kurent. Continually maintained and meticulously cared for, both aircraft go quite some distance beyond normal museum specs and retain pretty much all of their operational fittings – including the engines and complete cockpit setups…

3. Republic F-84G-31-RE Thunderjet, 10642

The first of the pair to be featured, 10642’s story in many respects closely parallels that of the IF-86. However, while it too was produced in significant numbers – with 7,254 examples completed – the Thunderjet is nevertheless a much rarer sight today, with virtually all of the few surviving examples confined to a couple of (distant) museums in the West. Even more astounding is the realization that of the 231 (!) F-84s delivered to the YuAF, only 10642 and 10525 (of the Aeronautical Museum in Belgrade) still stand as display-grade examples, with most of the rest having either been sold or scrapped ages ago…

Looking quite fresh for its age (which says a lot about the quality of the restoration work!), 10642 had rolled off the production line in 1953 as part of the type’s third production series. Sporting the factory serial 3050-1829B and provisional USAF identity of 52-2910, it would be delivered the same year to the Italian Air Force, becoming MM52-2910 of the 5 Aerobrigata.

Following the end of Italian F-84 operations in May 1957, 10642 would be transferred to the Yugoslav Air Force as part of the continuation of MDAP, where it would take up its current identity as part of either the 82nd or 172nd Aviation Regiment of the 21st Division (the details are a bit hazy) based at Zemunik Airbase (ZAD/LDZD) on the Adriatic coast. Like virtually all newly-acquired aircraft at the time, 10642 would for awhile sport the original colors of its previous operator – bare metal in the case of the Italian AF – before being repainted into Yugoslavia’s standard camouflage pattern some years down the line (as excess funds became available).

At some point during its lifetime, 10642 would be transferred to the 82nd Air Brigade stationed at Cerklje ob Krki Airbase, Slovenia (LJCE), where it would continue to serve until its retirement in 1971. As was the standard modus operandi at the time, a couple of the type were picked up and placed as gate-guards at various locations of note, with 10642 having been allocated to Brnik alongside Sabre 14325 – gaining, like the latter, a non-existing identity (10914) in the process. Here it would remain unkempt for the next thirty or so years, before finally being rescued by Mr. Potočnik and the Museum in 2008.

Having been exposed to the elements – including high winds and snows – for more than three decades, the aircraft was, unsurprisingly, in a pretty poor state, requiring an extensive ground-up restoration that would continue well into 2013. Emerging from it looking like it had just rolled off the production line, 10642 was then placed in the open in the Park – from where it will move to the aforementioned permanent indoor location in September of 2015 :).

4. Soko HO-42 Gazelle, TO-001

Conversely, the last machine on the list doesn’t really have much in the way of rarity on its side; however, what it lacks in that department it certainly makes up for in historical significance :). The Park’s only rotary-winged exhibit, TO-001 is often hailed as one of the most important aircraft in newer Slovene history – and is still ranked as one of Mr. Potočnik’s (and his team’s) best restorations…

Locally still considered to be one of the very few aircraft of any sort to fully live up to its name, the superlative Gazelle has always had a special connection to Yugoslavia, having been the mainstay of its light helicopter forces ever since its introduction into the YuAF in 1973. Still flying on the front lines in Serbia and Bosnia and Herzegovina today, the SA-341 is pretty much part of the aeronautical landscape, a reputation no doubt due to both its stellar flight performance – and its long-lasting license production***** by the Soko works in Mostar, Bosnia :).

***** of interest, during the 70s and early 80s, Yugoslavia had gone on a number of mass hopping sprees all throughout the West, purchasing significant batches of everything from the Cessna 150, via the Bell 212, to the HS.125 bizjet. Numbering well into the treble digits of machines, the intent of these acquisitions was to prop up the country’s aviation sector by equipping flying clubs, schools, government agencies, larger companies – and even police air units – with modern, capable Western hardware.

Interestingly, all throughout the deal, the country’s purchasing committees had always shown a clear preference for aircraft designed in the US, but if at all possible manufactured somewhere in Europe – or even at home, if the production capabilities so allowed. Thus most of the smaller Cessnas bought were actually Reims machines – and most Bell helicopters were in fact Agustas (the only exceptions were aircraft not produced anywhere but in the States). Eventually, the only type to be built whole in Yugoslavia was the Gazelle (starting in 1978 from knock-down kits) – though license manufacture of various components (such as the Bristol-Siddeley/Rolls-Royce Viper turbojet) had been relatively widespread.

To differentiate them from original French-built examples (only 21 of which had ever been delivered to Yugoslavia), Mostar-produced examples came in a variety of designations******, including:

HO-42: a basic version equivalent to the military-export SA-341H (HO – helikopter opšti, general-purpose helicopter)

a basic version equivalent to the military-export SA-341H (HO – helikopter opšti, general-purpose helicopter) HI-41 Hera: a reconnaissance and artillery-fire correction model based on the HO-42 and equipped with the Hera gyro-stabilized laser range-finding system (HI – helikopter izviđački, scout helicopter)

a reconnaissance and artillery-fire correction model based on the HO-42 and equipped with the Hera gyro-stabilized laser range-finding system (HI – helikopter izviđački, scout helicopter) HS-42: a MEDEVAC version based on the HO-42 (HS – helikopter sanitetski, sanitary helicopter)

a MEDEVAC version based on the HO-42 (HS – helikopter sanitetski, sanitary helicopter) NH-42M GAMA: an armed SA-341 sporting the 9M14M Malyutka wire-guided anti-tank missile and the Strela-2M air-to-air missile (NH – naoružani helikopter, armed helicopter; GAMA – GAzela MAljutka)

an armed SA-341 sporting the 9M14M Malyutka wire-guided anti-tank missile and the Strela-2M air-to-air missile (NH – naoružani helikopter, armed helicopter; GAMA – GAzela MAljutka) HO-45: another basic version, but based on the more powerful SA-342L

another basic version, but based on the more powerful SA-342L NH-45M GAMA: the same as the NH-42M, but based on the HO-45

****** another interesting tidbit is that the Yugoslav military designation system had often contained numerical references to WW2. The 41 in HI-41 thus refers to the start of the war in Yugoslavia (initiated by the Axis invasion on 6 April), while the 42 in HO-42 refers to the year Partisan forced had first really made themselves felt in their fight against the German Army. And the 45 is rather obvious :D.

One of 157 examples made in total, TO-001 can trace its roots back to the second production batch of HO-42s, leaving the factory floor in 1979 with the serial 028 and YuAF code 12660. There follows a two-year gap in activity that I could not account for, but in 1981 it would be allocated to the 894th Helicopter Squadron for Reconnaissance and Signals based at Brnik. Its subsequent history would be relatively uneventful (apart from a minor landing incident in 1984) all the way until 25 June 1991, when all helicopters based at Ljubljana were transferred to the Šentvid Barracks north of town – just days before one of the opening shots of the 90s war, the 28 June aerial attack on Brnik.

Two days later on 27 June – the day Slovenia had declared its independence from Yugoslavia – the unit was deployed east to monitor the Slovenian-Croatian border, with 12660 additionally tasked with airlifting an injured soldier to hospital in the town of Maribor, located in the north-eastern corner of the country. The next day – 28 June – when piloted by captain 1st class Jože Kalan and aviation technician sergeant-major 1st class Bogo Šuštar, 12660 had defected to the Slovenian Territorial Defense forces, flying west out of Maribor at high speed along the Slovenian-Austrian border, and onwards to the Golte forest where it landed at a winter sports facility and surrendered.

Having subsequently been moved several times to confuse enemy intelligence – even hiding on farms on occasion – the helicopter would, in the event, play no further part in the war. Nevertheless, it would soon be rechristened TO-001 (TO – teritorijalna obrana, territorial defense) and named Velenje, a homage to the Slovene town of the same name whose TO ground units were tasked with its protection while on the run. In 1992 though, it would be transferred to the civil register as SL-HAA (SL being Slovenia’s first post-independence prefix, before being allocated the current S5) and repainted into an aquamarine scheme reminiscent of 70s Bell JetRanger factory colors. It would then continue to fly with the 15th Brigade of the nascent Slovenian Air Force, serving mostly in various training and light transport roles.

All of this would come to an end however on 21 June 1994, when (now) S5-HAA had suffered a landing accident at Kočevski rog in the south-east of the country. Deemed to be beyond economical repair (as the only one of its type in-country), it was instead restored to display status and in 1996 installed as a gate guard in front of the 15th Brigade’s HQ at Brnik. But, like Thunderjet 10642 and Sabre 14325, it had suffered greatly from its exposure to the weather (even though it was outside for a “mere” decade only), leading to a drive to restore and preserve it once again as an important part of the country’s recent history.

Taking place from August 2008 to its unveiling at Pivka on 27 June 2012, the restoration effort is still hailed as one of the biggest aeronautical history projects in Slovene history, and had involved a sizable team of 26 people – including numerous active military personnel and the crew that had flown it over on 28 June 1991 :). As is the case with the Thunderjet, the work had gone far beyond the usual museum standards, going on to include the entire cockpit, all ancillary equipment – and the complete Astazou IIIA engine…

I would also like to extend my sincerest thanks to: Messrs Potočnik and Kurent for their time, friendliness and forthcoming assistance; Mr. Svetozar Jokanović of the “YU vazuhoplovna istorija” group for information about the YuAF recce Sabres and their service lives; and Mr. Tomaž Perme for information on the project’s organization and various corrections of the machines’ individual histories!

Sources

Change log and revisions

13 MAR 2016 – added new details of the IF-86D mod