In one of those instances in life where innocent scrolling through aircraft photos leads to several hours’ worth of research, I am once again able to present one of my (unplanned 😀 ) historical works, borrowing now on a theme set by my previous PC-6 engine piece. The unsuspecting party this time is the pudgy Let L-410 Turbolet, one of the Czech Republic’s most notable and successful aircraft – and a machine that many in Eastern and Southeastern Europe associate with durability, practicality and robust versatility (alongside the An-2 naturally).
The train of thought that had derailed this time was the realization of the sheer number of L-410 variants out there – 39 by my count so far! – all identified by cryptic and complex shorthand such as “UVP”, “E-17”, “E-S”, “AB” and so on. Coming to terms that I’m (at best) a bit hazy on what they all actually mean, I’ve decided I might as well dig a little deeper and see if this mass of numbers and letters can be forced to make some sense… 🙂
Despite its apparent complexity though, the classic L-410 line can actually be split into only eight easily-manageable families. Given that various online sources give various specs and details for each generation, I’ve decided to go back to the absolute basics, and concentrate solely on the one definitive source – the Turbolet’s Type Certification Data Sheet (or TCDS), available both from the Czech Civil Aviation Authority and EASA.
But, since fiddling with the sort of detailed specs that can be found in such a document would defeat the purpose of a “clarification”, the aim of this article is simply to construct an overview of the general changes from family to family – and not a thorough analysis of all 39+ versions. To keep the comparison clean, tidy and understandable, only the bits that were changed between models are noted – with an exact side-by-side comparison of key performance specs and characteristics (also my own work) provided at the end.
So, starting from the top…
L-410 “originals” (6 aircraft): despite the Turbolet being most closely associated with the Walter M601 series engine, the type’s beginnings were actually tied to another turboprop great, the Pratt & Whitney Canada PT6A. While the L-410 had been designed from the outset with the M601 in mind, the engine was still not usable by the time the Turbolet was nearing the detail design stage in the mid-60s. In order not to hold up development, the Let works had soon decided to slot in a replacement engine, the PT6A-27, developing 680 SHP. Given that engine-propeller combinations are not really open to experimentation, the choice of a Western engine had necessitated the use of a Western propeller, in this case the Hamilton 23LF-343 three-blade unit with a 2.6 meter span.
Following flight and ground testing of the four XL-410 prototypes, the design was finally “frozen” at the beginning of the 70s, subsequently entering production in 1971 as the L-410. However, only six aircraft of this series were ever produced – with all having subsequently been converted to the L-410A standard.
An interesting detail – first seen on the final two prototypes – was the de-icing system, which had dispensed with standard pneumatic boots in favor of a TKS fluid system. Increasingly popular on today’s high-performance GA aircraft, this system works by bleeding a special glycol-based fluid through micro pores on the wing and tailplane leading edges, preventing the accumulation of ice. While the system is significantly more effective than classic boots, the protection provided is dependent on the quantity of fluid carried – a factor that had limited the aircraft’s exposure to icing conditions to only 40 minutes.
L-410A (25 aircraft): picking up where the original left off, the A model was introduced at the beginning of 1972, but had essentially differed only in the propeller fit – with the Hamiltons giving way to Hartzell HC-B3TN-3D units with the same three blades and 2.6 meter span. Interestingly, some sources state that this version had also introduced a Maximum Take Off Mass (MTOM) increase to 5,700 kg from the original’s 5,400 kg; however, the TCDS states that both the original and A models were certified for the higher mass.
Sub-versions include the L-410AB, L-410AF and L-410AS
L-410M (108 aircraft): by the mid-70s, the M601’s bugs had finally been ironed out, making it suitable for installation on the Turbolet. Debuting in 1975, the M would be fitted with the increased-diameter M601A unit, developing 740 SHP and whirling three-blade Avia V508 propellers with a 2.5 meter span. Despite the increased power, this new setup had actually had a slightly detrimental effect on performance, with cruise speed now reduced by 10 km/h / 5 kts to 350 km/h / 189 knots, and ceiling by 100 m / 300 ft to 6,000 m / 19,700 ft.
The switch to the M601 had also marked the end* of the TKS de-icing system and the return to standard pneumatic boots, resulting in the lifting of the 40 minute restriction for flight in icing conditions.
* however, I’ve been told that the TKS system was actually discontinued in 1974, so it may be possible that a handful of the final A models were also fitted with boots…
Sub-versions here include the L-410MA/MU (such as OM-PGD from the featured photo)
L-410UVP: as was the case with many Eastern European aircraft, the Turbolet’s main market was – by default – the USSR, especially in the hands of the state behemoth Aeroflot. Having originally instigated the development of the L-410 as a potential substitute for the vast fleets of An-2s still being used on commercial services, Aeroflot had naturally been interested in getting the most out of the design, having had some reservations about the M model’s ability to operate in the Soviet backwoods. Under the airline’s urging, Let had in 1979 introduced the improved UVP, whose primary claim to fame was full STOL performance (with UVP being short for ukorochennovo vzlyota i posadki, or “improved take-off and landing” in Russian).
While at a glance it looks just like its predecessors, this new model is in fact a somewhat larger machine, sporting a 0.8 meter fuselage stretch (for a total of 14.17 meters in length) – and, critically, a 2 meter increase in wingspan to 19.48 m. Fitted with a pair of ground spoilers to dump lift on landing, these changes were in theory all that was needed to achieve the required short-field performance.
However, all these mods had also resulted in a significant increase in empty weight, which – without an appropriate increase in MTOM – had led to a reduction in payload (despite the extra room on board). Further complicating matters was the revised powerplant, now taking the form of the 700 SHP M601B and its associated Avia V508B propeller – making for an 80 HP deficit at take-off. This problem would be mitigated somewhat in 1983 with the introduction of the 735 SHP M601D and Avia V508D – as well as Service Bulletins which, when implemented, allowed an MTOM increase from 5,500 to 5,800 kg for the M601B and 6,000 kg for the M601D.
Despite this, the added bulk (and re-certification to Soviet standards) had also resulted in a reduced ceiling of 4,250 m / 14,000 ft, and a reduction in passenger capacity from 19 to 15 (not even swapping the metal rudder for a fabric-covered one had helped bring the weight down).
The sub-versions of this family include the L-410FG and L-410T
L-410UVP-E: to cure the UVP’s ills, the Let works would in 1986 debut the further improved UVP-E (E for ekonomicheskiy, or “economic”), also known briefly under the tongue-twister L-410UVP-L-E. This would be fitted with the 760 SHP M601E or E-21 engine (the latter intended for hot-and-high conditions), spinning more substantial Avia V510 five-blade propellers with a 2.3 meter diameter and fully automatic autofeather system. Even though cruise speeds had remained the same as on the UVP, the new aircraft could boast significantly higher maximum weights, with an MTOM of 6,400 kg and a Maximum Landing Mass (MLM) of 6,200 kg.
Apart from regaining its 19 passenger capacity (in part due to the reconfiguration of the rear baggage compartment), this version had also introduced optional tip-tanks, which together added 315 kg of fuel to its basic 1,000 kg internal capacity. Other changes had also included a revised avionics setup, now fully compatible with both Western and Eastern ground navigation aids – as well as the reintroduction of limitations for icing conditions, with the E now restricted to low and moderate icing down to a minimum temperature of -20 degrees Centigrade. The reason for this turn of events is somewhat uncertain, but was suggested to be due to the design of the oil-to-fuel heat exchanged fitted to this model, which could lead to the overcooling of both the oil and fuel in extremely low temperatures.
Sub-versions were greater in number, including the L-410UVP-E1, E2, E3, E4, E6 and E8
L-410UVP-E9: a further update of the basic UVP-E, debuting in 1988. Generally identical, the E9 had only introduced MTOM and MLM increases to 6,600 and 6,400 kg respectively
Sub-versions include the L-410UVP-E9A, E9D, E13, E14, E15, E16, E17 and E19
L-410UVP-E20: what would eventually become the definitive classic Turbolet had appeared in 1990, sporting only a 40 cm fuselage shrink and a (once again) restored ability to continuously operate in icing conditions (likely due to the removal of the offending heat exchanger). While this had hardly set the world alight, the changes “on paper” were much more significant, with the E20 being the first of the family to be fully certified against both FAA FAR 23 and (today’s) EASA Part 23 regulations. Being “universally accepted” in the world had also meant that the E20 would remain in production until this day, with new builds still being delivered left and right at the time of writing.
Sub-versions include the L-410UVP-E20C, E20D, E20G and E27
L-410UVP-EPT (one aircraft): in what would become an interesting piece of circularity, 2016 would see the Turbolet’s return to PT6 power with the EPT, a third-party conversion penned by Aero Servis of the Czech Republic. Having become dissatisfied with General Electric’s handling of the M601 program – citing rising costs and dropping support quality – the company decided to replace the Walter with the more potent PT6A-42, flat rated to 800 HP and spinning a modern Avia AV-725 five-blade aluminium propeller. Though Aero Servis does not cite any performance figures, they do say that the installation reduces fuel consumption and noise, while increasing both hot-and-high performance and the maximum cruise speed.
As of SEP 2021 when this chapter was added, only one aircraft has so far been converted.
L-420 (one aircraft): the last of the Turbolet classics, the L-420 also had the dubious distinction of creating confusion far greater than its “production run”. Introduced in 1998, the 420 was often labelled as just a re-branded E20; however, in reality, the model was actually another refresh of the E line, intended for certification and export to the US market. Sporting 790 HP M601F engines driving the same V510s, the 410 could boast a top speed of 375 km/h / 202 knots and an “A level” ceiling of 6,100 m / 19,700 ft. Interestingly, the aforementioned FAR regulations had necessitated a number of unusual changes to the basic design, including the removal of the engines’ Integrated Electronic Limiter Unit (IELU) – which would reduce engine power in case any of its parameters were exceeded – the addition of a passenger door on the right side of the fuselage (identical to the one on the left) and reinforced flight control linkage.
Despite the increased performance and the additional changes, the design had not fared well against Western competition, with reportedly only one aircraft made – and a test conversion from a stock E20 at that (though it is now normally flying in commercial operations).
L-410NG – the new kid on the block: even though this one doesn’t count towards the classic family tree, I’d decided it would be unfair to skip over it – especially since it picks up the baton of the L-420. Having flown for the first time in 2015, the NG is essentially a thoroughly updated current-production E20, marketed (ironically) primarily to operators in the former USSR. The highlights of its transformation include a three-screen Garmin G3000 glass cockpit, composite materials in non-critical areas (such as doors), an elongated nose for increased baggage space – and a significant power boost in the form of the 850 SHP General Electric H85-200 unit and its associated five-blade Avia AV-725 prop. While the latter sounds like quite the change, the engine in question is actually a modernized M601, born during GE’s purchase of Walter.
The extra grunt naturally promises increased performance and capability, with an MTOM of 7,000 kg, MLM of 6,800 kg – and cruise speeds now in the 420 km/h / 227 knot range. Interestingly, the update also includes a significant boost in fuel capacity, with 2,340 kg now available with tip tanks, versus 1,315 for an equivalent E20.
The Devil Is In The Details
Given that the above pretty much covers 75% of the Turbolet’s family tree, I thought it a shame not to list – at least in passing – some of the aforementioned sub-versions. However, as they are not contained or listed in the TCDS, this review is based on various human and online sources and includes just a short snipped of what made the version special or different… 🙂
L-410AB: the L-410A fitted with Hartzell HC-B4TN-3 four-blade propellers
L-410AF: a one-of aerial photography and cartography version with a glazed nose and fixed nose wheel
L-410AS: ten examples built for the Soviet market, with upgraded navigation and communication equipment. Used to test the design’s suitability for use in the USSR
L-410MA: a standard L-410M refitted with the UVP’s M601B engine and V508B propeller
L-410MU: an alternate designation for the L-410MA
L-410FG: identical in function and configuration to the L-410AF, but based on the first UVP; seven produced. Interestingly, to enable the camera operator to reach his station in the nose, the copilots control column had to be removed; despite this, the aircraft had remained a two-pilot machine. It is unknown however (though likely) that the AF had also “suffered” from the same issue
L-410T: a standard UVP modified to be able to better handle freight, with a larger cargo door and cabin modifications to be able to accommodate pallets, stretchers and bulky cargo
L-410UVP-E1: two aircraft for Bulgaria, reportedly for a mixed photography/transport role
L-410UVP-E2: a modified version for the Polish Maritime Office
L-410UVP-E3: version optimized for skydive operations
L-410UVP-E6: navaid calibration version
L-410UVP-E-S: a “salon” VIP version with integrated steps and plush interior
L-410UVP-E4 & E8: exact details unknown
L-410UVP-E9A: a version for the Swedish marked fitted with Bendix/King avionics
L-410UVP-E9D: a sole example modified with a Bendix/King EFIS cockpit system
L-410UVP-E14: another model with Bendix/King avionics, intended for the transport of military dignitaries
My regular readers will no doubt recall me often going on about the rich and textured history of Lučko Airfield, a small and unassuming grass strip on the edge of town that had over the years produced a good chunk of the country’s pilots – myself included :). Nowadays a quiet place that can send you to sleep within minutes, Lučko nevertheless has a varied and interesting past, having been everything from a commercial airport, to a WW II airbase, to today’s joint sport field/helicopter base since its beginnings back in the mid 30s. But while this roller coaster development had made for some excellent Achtung, Skyhawk! material, most of the time it was wasted on my ground-level perspective, offering only limited ways in which to chronicle and evoke the finer details of the field’s history.
A few weeks ago however I had the great fortune to be taken up for a short hop in an ultralight trike (a fascinating experience I must say!), finally allowing me a proper bird’s eye view, free from the constrains of windows, doors and that incessant necessity of having to continually look where I’m flying :D. So, for a short historical interlude, here’s Lučko’s history as read from the air :).
So, starting from the lower left corner we have:
the old WW II runway, whose remains today make up most of the main apron. Used in some form of military capacity ever since its opening, Lučko was initially home to a squadron of Messerschmitt Bf.108 Taifun liaison aircraft operated by the air force of the Kingdom of Yugoslavia. Following the German invasion of 1941, the airfield was – not unsurprisingly – reformed into a fighter base, becoming home to Bf.109s, Dornier Do-17s and Fiat G.50s of the Ustaše, the Fascist puppet government that came to power in the wake of the invasion. Though it’s hard to be entirely sure – many documents from the period having been either destroyed or classified – this runway was one of two used by these aircraft, stretching roughly in a 31-13 direction over a distance of at least 500 meters…
the current control tower in the top left corner (with the green roof), a cheap-and-cheerful affair that more than adequately serves the field’s needs 🙂 (as well as my own photographic ones when I want an elevated view 😀 )
slightly to the right is the field’s newest hangar, completed only a year or so ago and home to a nice selection of (rather rare) motorgliders
further right and sporting a grey roof is the old WW II hangar, one of two that had originally been located at Borongaj airfield, but moved to Lučko sometime in the 50s when Borongaj had ceased operations. Home to the small fleet of the AK Zagreb flying club, this hangar is pretty much the only piece of 40s aviation infrastructure still in use at the airfield, though its tattered insides and leaky panels definitely show its prime has passed…
dominating the scene next to it is the HZNS hangar, owned by my former University and home to its five-strong air wing (that had seen me through my CPL training 🙂 ). The largest and most modern single facility at the field, it boasts proper all-round heating (!), simulator facilities, offices and a handy classroom for preflight preparation (and post flight bantering). Doesn’t sound like much, but it’s the closest thing we have to a proper training facility in the area…
on the extreme right though is one of the most overlooked buildings at Lučko, its original passenger terminal and control tower :). A leftover from the field’s commercial heyday in the late 40s and 50s, it is nowadays abandoned and pretty much forgotten, having become just another obstacle to bypass when pulling into the parking lot. Up until a few years ago, it had also been home to Aerotel, a sorely missed “watering hole”, and had even included rudimentary sleeping facilities for out-of-town crews wishing to overnight for not much money. While there were several recent attempts to clean the building up, nothing much had come out of them, with the entire building condemned to slow decay..
and finally, at the bottom of the shot is the field’s de facto main operations building, which houses a briefing room, auditorium, offices for the various local flying clubs – and the inevitable storage facilities for everything from parachutes to gliders :). Another oldtimer, this building has been part of Lučko’s cultural identity ever since sport flying kicked off in the 60s, having been the site of pretty much every social event, meeting and award ceremony at the field for half a century… 🙂
Author’s note: while not a new topic per se, the Bf.108 has turned out to be quite a popular item on this blog, with my previous post rising to an all time high viewcount. In view of that – and my “temporary”, two-year-old promise to finally sort out the post’s missing images – I’d decided I might refresh it, and post it in a format consistent with the new look of this site 🙂 .
When the first Bf.109s faced their German rivals in mock dogfights in the mid 30s, few observers – in any country – were left in doubt about the capability and raw potential of Messerschmitt’s first fighter design. International flying competitions during the run-up to WW 2 had only confirmed these impressions – but it would take the type’s impressive (though in later years somewhat diluted) wartime service record to finally remove all doubt. Lasting more than a decade in one form or another, the type’s all-up production run had encompassed more than 35,000 examples, spanning everything from the prewar lightweight Bf.109B Berthas to the post-war Merlin-engined Hispano Buchons.
A very advanced design by contemporary standards, the Bf.109 was not actually ground breaking per se; when all was said and done, it had not really introduced anything new or revolutionary into world of interwar fighter design. Rather, what it did – and did brilliantly – was to combine all the cutting edge technologies available at the time into a single aircraft: the monoplane configuration with its high wing loading; the powerful liquid-cooled V engine and its variable pitch prop; fully retractable hydraulically-actuated landing gear; the enclosed cockpit…
Other design features – which soon became the type’s hallmarks – had also included automatic leading edge slats and an innovative construction technique that had made the aircraft extremely light by the fighter standards of the day. The latter had also made the 109 simple and cheap to build, quick and easy to service – and especially tough, durable and reliable under actual combat conditions (though the rigors of the Soviet campaign would put its mettle fully to the test). And while the big engines and retractable landing gear and the monoplane configuration could easily be traced to some of the eminent fighter aircraft of the era, the above features were inherited from a decidedly more peaceful source – the lowly Bf.108 tourer 🙂 .
When I grow up I want to be a fighter!
The aircraft that would eventually lend its technical solutions – not to mention most of its airframe – to the Bf.109 had started out in life as the four-seat* M.37 tourer prototype of 1934. Designed by the young Willy Messerschmitt, Bayerische Flugzeugwerke‘s chief designer, the M.37 was conceived primarily to compete in the 4th Challenge de Tourisme Internationale being held the same year. This interesting – and I’m sure sorely missed – general avation competition was intended to promote and spur the development of light touring aircraft, and had included such competition categories as “Short Takeoff”, “Short Landing”, “Fuel Consumption”, “Minimum Speed”, “Maximum Speed” and “Technical Trial”. Topped by an (at the time) grueling and arduous 9,500 km rally across the diverse spaces and climates of Europe and North Africa (stopping also in Zagreb 🙂 ), this competition was intended – much like the 24 Hours of Le Mans in the automotive world – to weed out inferior designs and encourage quality solutions for future touring aircraft.
* though designed as four-seaters, the M.37 and the early Bf.108 were actually flown as two-seaters, with the rear seats permanently removed to provide some storage space. With virtually all pre-series production versions having been used for competitions and proving flights, this gave impression that they were designed outright just for two…
Based in part on Messerschmitt’s previous M.29 tourer – designed in a similar manner for the 1933 competition, but never taking part due to a spate of crashes – and the M.35 aerobatic trainer prototype, the M.37 was a sleek and elegant all-metal, stressed-skin low-wing monoplane, sporting retractable main gear, an enclosed (and heated) cockpit, full-span flaps – with roll control provided by roll spoilers (in 1934!) – and a variable pitch prop… all of which had immediately made it stand out like a sore thumb in the wood & fabric biplane crowd of the time 🙂 . This brazen level of unorthodoxy had continued under the skin as well, with the wing being built around only one spar – a design that was made to work thanks primarily to Messerschmitt’s extensive glider building experience gained during the restrictions of the Versailles Treaty. The innovative mechanical leading edge slats could be extended manually to improve the airflow over the wing’s outer sections – which were likely to stall first – reducing the stall speed to just 61 km/h (33 knots). This in turn helped to significantly shorten the aircraft’s take off roll – not to STOL levels, but not far above either – and dramatically increased low-speed maneuverability, handling at high Angles of Attack, and behavior in, during and after a stall.
As with the wing, the whole design philosophy was to make the aircraft as simple as possible, using the fewest realistic number of parts needed to make a light and durable airframe. Pure functional minimalism. And it had worked, and worked well – compared to similar designs of later dates, the M.37 was indeed among the lightest and best performing. Official flight testing prior to the 4th CdTI was marked by the general enthusiasm of all pilots that had flown it, prompting the German Aviation Ministry – the Reichsluftfahrtministerium, or RLM – to give the aircraft a tentative green light as the Bf.108*.
* of note here is the oft-confused and misinterpreted designation. Popularized by the 109, the “Bf” prefix stood for the initials of “Bayerische Flugzeugwerke” (itself often shortened to BFW); however, when the company was renamed to “Messerschmitt Flugzeugwerke” in 1938, all subsequent designs were given the new “Me” prefix. The designs that had been produced before the name change had retained their original prefixes through the war – so there never was an “Me-108” as is claimed by some Internet sources.
However, despite the praise and the design’s undoubted qualities, one feature of the 108 had never really sat well with some of the test pilots: the roll spoilers. With the full length of the wing’s trailing edge taken up by the flaps – which increased the wing area by a significant 8% when fully extended – there was no space for traditional ailerons; roll control was instead provided by roll spoilers located on the wing upper surface, whose extension would create a difference in lift along the span of the wing. For example, if you had wanted to roll left, the spoilers on the left side would extend, dumping lift on that part of the wing. The wing’s ride side would now be producing more lift, which would roll the aircraft left around its center of gravity in the same manner as the ordinary aileron. This was fine in theory – and is today still used to provide additional roll control on a number of civil and military designs – but back in the 30s it was viewed with suspicion and more than its fair share of antagonism. This came to a head when test pilot von Dungern was killed while testing the spoilers, presumably somewhere near the edge of the envelope.
With the RLM’s well documented dislike of Willy Messerschmitt threatening to ground the Bf.108 – like it had the M.29 a year before – there was no other option but to revert to a conventional aileron arrangement. “Conventional” though should be taken with a grain of salt when Willy is concerned, because the resulting arrangement had still managed to raise an equal number of eyebrows… 🙂
In this form the aircraft became known as the Bf.108A, the designation under which it would be entered in the competition. Sadly, its beautiful handling and avantgarde features did not really help its case there, with the far lighter, nimbler and simpler wooden biplanes wiping the floor with it for most of the competition…
However, the 108 did eventually notch up several notable wins, all of which would eventually steer its development into the aircraft we know today. The top three aircraft in the “Fuel Consumption” category for example were all 108s – with the winner registering an impressive 10 kg (14 l) / 100 km. This figure – nowadays exceeded even by a basic SUV – was made even more impressive by the fact that the 108A was not powered by a small, frugal, fuel-sipping engine, but a 220 HP Hirth HM 8U inverted V8 (a proper GA engine 😀 ). Its power and torque had also helped in the “Maximum Speed” event, where the 108s again took the whole podium, with the slowest – at 283 km/h (153 knots) – being 30 km/h (16 knots) faster than the next contender. The trans-European rally was less of a success though, with the 108’s best result posted by Theo Osterkamp, who placed fifth. However, this poor showing was more due to the scoring system – and external influences such weather and poor navigation – than any faults with the aircraft themselves. Points were awarded based on total average speed, BOTH moving and stationary; this had meant that a fast aircraft grounded by weather for extended periods would score less points than a slow aircraft that had managed to evade the worst of it and continue flying. When everything fell in place though, the 108s had regularly posted the fastest average flying speeds – including on the legs to and from Zagreb 🙂 .
In the end, when the tally was done, the 108s had placed 5th, 6th and 10th out of a grand total of 19 contenders. But more importantly, their demonstrated low fuel consumption, high cruise speeds and beautiful handling – not to mention a leather upholstered and heated cockpit! – had immediately lent them well to cross-country touring. A clean, aerodynamic airframe, able to zip along on comparatively little power – sounds much like the Lancairs and Cirruses of today, doesn’t it? 🙂
This did not slip past the cash-strapped BFW, where Messerschmitt had decided to capitalize on the type’s competition success by adapting it for series production. To this end, a batch of pre-production Bf.108B-0 models was made (though they were still commonly known as the Bf.108A), with each successive aircraft representing a slight step toward a definitive production standard.
By 1935, these aircraft had already started making a name for themselves – some quite literally 🙂 . Well established as the fastest tourers in the sky, one example was chosen by famous German aviatrix Elly Beinhorn for her record breaking flight from Berlin to Constantinopole (now Istanbul, Turkey) and back. Her little Bf.108B-0 had more than lived up to its Taifun nickname when it took just 13 and a half hours to do the 3,470 km trip, flying along at an average ground speed of 257 km/h (139 knots) – a respectable result even by today’s standards.
This very convincing – and, at a time when the nation was hungry for records, very public – success had immediately opened the floodgates, and the 108’s already significant popularity skyrocketed overnight. As was the case with its showing at the 4th CdTI, this had not gone unnoticed at BFW, where Willy Messerschmitt increased efforts to finalize the Bf.108B-0 into a definite, production, high performance cross-country tourer. The end result was the Bf.108B-1, now adopting Taifun into its official name 🙂 .
While there was nothing really wrong with the original A series (and the early B-0s) performance-wise, they did have several features that were judged to be unfit for a production version. The whole idea behind the B-1 was to make the aircraft more production- and consumer-friendly, so the first item to go was the original’s powerplant. The expensive and hard-to-come-by VDM three-blade variable-pitch propeller was replaced by a simpler and cheaper two-blade fixed-pitch prop (although Messerschmitt’s own P7 variable-pitch unit was offered as an option), while the HM 8U engine was swapped for the more readily available Argus Ar 10C inverted V8, producing 240 HP. The wing was a bit dulled down as well by a reversion to a fully conventional aileron and flap arrangement – but had compensated for it by gaining a folding mechanism that allowed it to be tucked close to the fuselage for easier transport by road and rail.
Additional minor changes included the removal of the upper tailplane bracing mentioned previously, the replacement of the next-to-useless tailskid with a non-retractable, freely castoring tailwheel, and the shortening of the glazed canopy over the rear seats.
In this shape and form, the aircraft had continued to participate in international competitions, rallies and fairs (and, most notably, the 1936 Summer Olympics in Berlin) – but now under the increasingly ominous banner of Nazi propaganda. Indeed, soon after its initial competition successes, the fast-growing Luftwaffe had started eying the 108 as a liaison and communications aircraft to replace the obsolete, lumbering biplanes then being used.
However, the 108’s biggest contribution to the Wehrmarcht’s war effort was as the basis and jumping-off point for the impressive Bf.109 – a fact that in itself further underscores the essential quality of the Taifun’s design. In a fantastic display of lateral thinking, in 1934 Messerschmitt had simply taken the plans for the 108A and modified the design into a single-seater with a narrower fuselage, a big V12 up front – a “right way up” Rolls-Royce Kestrel on the first prototype (oh, the irony 😀 ) – and some firepower in the slightly modified wings (which too had reverted to a conventional aileron/flap arrangement). Apart from other smaller changes needed to fit all of this together, the rest of the new aircraft was a straight 108 🙂 .
While the wildly differing roles of these two aircraft may have raised some eyebrows – not to mention questions about Willy Messerschmitt’s command of his senses – the 108 was actually an amazingly suitable base for the 109. The Taifun’s advanced construction meant that the 109 could be light and maneuverable – as was demonstrated on more than one occasion over the next decade – and its relatively low part count meant it was simple to maintain and repair in the field with whatever facilities were on hand. Lacking complicated construction components also meant that it was very tolerant of combat damage, and the low number of critical design points made disabling it with a “lucky shot” quite the enterprise. At the same time, the clean airframe sliced through the air with relative ease, meaning the 109 could do with relatively little power and a smaller, more economical engine – quite a welcome feature given its notoriously short range and pitiful combat radius.
But an interesting and varied operational history was not just the prevue of the 109. Having had the (mis)fortune of being the most advanced light aircraft in the world during a period of significant – and often rapid – political changes, the Taifun had naturally accumulated its fair share of odd operators. Apart from the “usual” Axis users such as Bulgaria, Romania and Japan, there were also a few unexpected ones like China – and the Royal Yugoslav Air Force. The dozen or so B-1s acquired in 1939 were part of a larger batch of aircraft that had also included 60 Bf.109Es and quantities of spare parts – all paid for not with actual money, but in strategic materials such as iron, copper, aluminum and coal… materials abundant in the Kingdom of Yugoslavia, but scarce and badly needed for the military buildup in Germany.
And while the 108s would go on to lead rather uneventful lives in training and liaison roles, the 109s would pretty soon enter the history books 🙂 . The most potent fighter aircraft fielded by the Royal Yugoslav AF at the time of the German invasion in 1941, these machines would go down in history as the only 109s to ever face other 109s in outright combat, clashing violently during the spirited – but ultimately futile and short-lived – defense of Belgrade.
Next on the scale of the improbable was – the US military 🙂 . While it was quite common for the USAAF to fly and evaluate captured Axis aircraft, the single Bf.108B-1 it had operated had never even left Germany – and was actually peacefully bought, rather than forcefully captured. Designated the XC-44, this interesting aircraft had been based in Berlin and used as a high-speed staff transport by the US Military Air Attache up until 1941, when it was repossessed by the German government following the United States’ declaration of war against Germany and its allies.
Equally improbable – and, if anything, even more interesting – were the four Bf.108B-1s brought into the UK before the war. Bought on the “open market” just like the XC-44, but operated by civilian users, these examples were quickly impounded and pressed into RAF service at the start of hostilities, becoming the Messerschmitt Aldon. Used – like contemporary Luftwaffe examples – in the communications role, they were capable of comfortably outrunning every liaison type in the UK – though their shared family tree with the Bf.109 had often caused identification problems among defending fighters…*
* for those wondering how could the 108 be so easily mistaken for the obviously different 109: the first of the Griffon-engined Spitfires, the Mk XIIs, had been delivered with clipped wingtips intended to improve roll rates and increase maximum speeds at lower altitudes – a feature already well known at the time, and seen on virtually all Spitfires marks since the Mk V. On the ground, the Spit’s famous elliptical wing planfom was still very much obvious; up in the air however, things were somewhat different. On their first few sorties, only the mark’s new-found speed advantage had kept it safe from the attentions of patrolling Hawker Typhoons, which had mistaken their long noses and cut-off wings for those of attacking 109s…
The postwar period too saw its share of unusual operators, including Czechoslovakia (where the type was known as the K-70), Poland and even the Soviet Union, all of which had flown examples captured during the final days of the war. Another interesting operator – well known now for their very colorful 108s – was Spain, which had acquired several batches of the type during the Spanish Civil War and Franco’s subsequent ascension to power.
For the full photo history of the 108’s civil and military service around the world, you can visit the excellent pages below, a gold mine of fantastic information from which I’ve linked many of the photos above 🙂 .
Unlike its armed cousin though, the 108 did not go through new versions like pairs of socks. Apart from the B series, there was only one major production version, the D; equally, experimental and test versions were also few in number. However, what the latter lacked in quantity, they’d definitely made up in quality… 🙂
By far the most normal – and sensible – of these was the Bf.108C-1, an ungainly 1936 modification that had seen a B-1 airframe refitted with a Siemens Sh 14A-7 seven cylinder radial. Coupled with its increased frontal area and drag, the engine’s rather pitiful 160 HP – 80 HP, or 33%, less than the type’s standard Argus Ar 10 – made for some appalling performance, which saw the aircraft remain a one-of. However, while this version seems to be an unnecessary step backwards, there appears to have been some method in Messerschmitt’s madness after all. While there’s little concrete technical info available on the mark, the C-1 was most likely an insurance policy for the event that Ar 10 production became disrupted or sidetracked to other more important projects – a policy not unlike that later employed by Avro with the Bristol Hercules-engined Lancaster B II.
At the other end of the spectrum was a stillborn version that some sources also label as a C-1 – which, given the German aeronautical industry’s policy of reusing designations of failed models, was entirely possible. Diametrically opposed to the Siemens-engined version, this C-1 was to have been a high-speed model, fitted with a Hirth HM512 inverted V12 that would have developed an astounding 400 HP on takeoff! 🙂 Ground testing in 1938 though had quickly revealed that noticeable airframe vibration and buffeting was to be expected above 325 km/h, which would progressively become so severe that it could even tear the airframe apart. Given the scope of engineering changes that would be needed to make this version work – and the impending shift of the German military industry into high gear – meant the project was quietly dropped…
That the only way was up was quite literally demonstrated in 1939 by a specially-modified high-altitude Bf.108B-1 (lacking a special designation), built to capture the world altitude record for its class. Fitted with a supercharged Hirth HM508 inverted V8 producing 270 HP – and also providing air to pressurize the cabin – this aircraft had reached an impressive 9,125 m (29,930 ft) in the hands of Hirth’s managing director, Herman Illg.
Series production models were however less interesting – and had pretty soon started suffering from an acute case of Skyhawk-itis 😀 . If you took ten C172s of the same model and same production year and lined them all up, you’d be able to spot – with very little effort – at least one difference or unique feature on each aircraft… a different landing light here, a static port moved to there, a panel layout tweaked just so… and so on. As production ramped up, the Bf.108 became no different, with options and features freely flowing between versions. This had made sorting them by model a bit difficult and vague; however, after roving the Internet far and wide, I think I’d managed to hit the nail on the head in general terms:
B-1: the already-described base model
B-2: generally very similar, but with the wing fold system removed and the variable pitch P7 prop – offered as an option on the B-1 – fitted as standard. This version could easily be recognized by its thinner prop blades and slightly different propeller hub
D-1: debuting in 1941, this was the first model produced outright for military use, and had featured a modified vertical stabilizer, improved fuel feed system, more powerful electrics, a windscreen wiper and a new constant speed prop, being turned by an Ar 10R engine of the same power output as the C (of note here is that “variable pitch” and “constant speed” propellers are not the same thing. A constant speed propeller – standard today – automatically varies the pitch of its blades to maintain the same RPM regardless of throttle setting; the variable pitch prop however was fully manual, with the pitch having to be readjusted with every change of throttle or airspeed. The 108’s variable pitch prop was operated by a large circular handle in the middle of the panel – known among the type’s pilots as the “coffee grinder” – and had added quite a bit to the crew’s workload)
The D-1 would also signal the last of German Bf.108 production before the whole works were transferred to France at the beginning of 1942. In a bid to free up domestic production capacity for badly needed Bf.109s, the B-2 and D-1 were allotted to the factory of the Société Nationale de Constructions Aéronautique duNord – SNCAN, or simply Nord – just outside Paris, where they would remain until the end of the war in France – with interesting consequences.
Following the country’s liberation in the summer of 1944, SNCAN – having produced just 170 aircraft out of the type’s total production run of about 880 – found itself with a significant number of uncompleted airframes and engines. Deciding it would be a waste to just throw them all away – and desperate to gain a foothold in the country’s recovering economy – the top brass elected to restart production of the 108 in the guise of the Nord Pingouin (what a demotion – from an impressive meteorological phenomenon to a cute polar animal 😀 ). The first model, the 1000 Pingouin, was virtually identical to the Bf.108B-2, save for the reintroduction of the B-1’s folding wings and the refitting of the D-1’s improved vertical stabilizer.
Once these stocks had been exhausted, it was a relatively straightforward matter to re-manufacture the airframes from the original plans, the WW 2 production tooling having already been set up and waiting. However, the engines had proved to be a bigger challenge, having been produced in – and imported from – Germany during the war. The only way around this was to use a local engine of similar power; but the only unit available was the Renault 6Q family of six cylinder inverted inlines, a powerplant considerably longer than the compact Ar 10. But having no realistic alternative, SNCAN went ahead with the redesign, creating the long-nose 1001 Pingouin I. Powered by the 233 HP 6Q-11, this model was quickly followed by the 1002 Pingouin II, which upgraded to the slightly more powerful 240 HP 6Q-10 – and which would eventually become the most common of all the Pingouins.
These would eventually number at 286, bringing the 108’s overall total to a tad over 1,100 aircraft. However, I was unable to confirm with absolute certainty when French production had actually ceased – but given the type’s low rate of production, I’d guesstimate the aircraft had disappeared from the production lines during the early 50s.
Note: some of the surviving aircraft have since been retrofitted with standard Lycoming and Continental engines, and have shorter, broader and more oval cowlings. For the sake of simplicity, I decided only to represent the original Renault-powered models here.
A (third) leg to stand on
However, the end of the Pingouin was not the end of France’s 108 connection 🙂 . Back in 1943, SNCAN – under prompting and guidance from Messerschmitt – had started working on an experimental tricycle version of the Bf.108B-2, which would have been known as the Me-208 (since this version was conceived after the creation of the Messerschmitt Flugzeugbau, it was allocated the Me prefix). Two prototypes were built during the last days of the occupation of France, but only one would actually survive to its end, later to become known as the Nord 1100 Noralpha. As in the case of the 108, SNCAN had decided to see the design though to the end – having already done 90% of the work – and market it under its own name. The result was the 6Q-10 engined 1101 Noralpha (known in French military service as the Nord Ramier, or “dove”), whose production ran to the 205 mark.
Much like the 108, the Noralpha did not see much in the way of different versions, but had compensated for it by a history of use as an engine testbed 🙂 . The first (rather conservative) iteration was the planned, but never built, 1102 Noralpha II, which would have been powered by the 6Q-11 seen on the Pingouin I. This version was followed by the slightly more successful 1104 – which had actually made it to the prototype stage, but no further – powered by a Spanish Potez 6Dba engine of the same configuration and power output as the 6Q-10.
However, the ultimate expression of power – and arguably of the entire 108 line – came in the form of two 1959 SFERMA-Nord 1110 Nord-Astazous. A project of the equally long-named Société Française d’Entretien et de Réparation de Matériel Aéronautique – SFERMA, a company formed in 1949 for the purpose of repairing and overhauling civil and military aircraft – the 1110s were conceived as testbeds for the in-development Turbomeca Astazou turboprop. The first example started out in life as the 150th 1101 Ramier produced, and was initially fitted with the 467 HP Astazou I. A bit later in the program, this aircraft – along with an additional 1101 – was re-equipped with the more powerful 550 HP Astazou II, as well as a host of other modifications including shorter span wings with cut off wingtips and vertical tail surfaces of increased size (to provide more stability at higher speeds).
Like the Me-208 though, only one of these amazing aircraft would actually survive to fly another day once the Astazou test program came to an end. Owned and operated by the Association Antilope under the reg F-AZNR, the above pictured example is still airworthy and beautifully maintained, happily plying the airshow circuit in France on a regular basis 🙂 .
The wind that keeps on blowing
While the type’s prime – in any version – had passed a long time ago, its status as one of the preeminent touring aircraft of the 30s had naturally had an effect on its current status of a desirable WW 2-era warbird 🙂 . Most estimates suggest that somewhere between 25 and 30 Taifuns and Nords are still airworthy today – a number of which are, unsurprisingly, operated in Germany. Aside from Messerschmitt’s own historic flight – the previously mentioned MesserschmittStiftung, part of the EADS consortium – another famous 108 operator is Lufthansa’s vintage aircraft division, the Lufthansa Stiftung. Possibly the best known of all surviving 108s, the company’s silver B-1 – registered D-EBEI – also shows that there’s still some mischevous spirit left in one of the world’s most serious companies; for a Taifun named Elly Beinhorn was just too good an opportunity to pass up 😀 .
Since keeping track of all the 108 versions can be a handful – and was quite a frustration for me as I was writing (and rewriting) this 🙂 – I’ve decided it would be prudent to sum them all up in one place, along with a few of their distinguishing features:
the first prototypes, used for initial flight testing and equipped with roll spoilers
the designation adopted during acceptance tests, identical to the M.37
1934 competition version, modified with short-span ailerons
pre-production series, each aircraft incorporating slightly different features
the first production version with folding wings, Argus Ar 10C engine and fixed-pitch prop (Me P7 variable-pitch as an option)
B-1 with folding wings removed and the P7 fitted as standard
initially a Siemens radial version; later reused on the proposed HM502 V12 high-speed model
final German production version fitted with a constant-speed prop, Ar 10R engine, more powerful electrics, improved fuel system and a modified vertical stabilizer; produced mostly in France
Nord 1000 Pingouin
post-liberation Bf.108B-2s, incorporating the B-1’s folding wings and the D-1s vertical stabilizer
Nord 1001 Pingouin I
new-build 1000s fitted with the 233 HP Renault 6Q-11 engine
Nord 1002 Pingouin II
new-build 1000s fitted with the 240 HP Renault 6Q-10 engine
two prototypes of the Bf.108B-2 modified with tricycle gear, designed in France
Nord 1100 Noralpha
the post-war designation of the only Me-208 prototype to survive the occupation of France
Nord 1101 Noralpha I / Nord Ramier
production-standard 1100s fitted with the 6Q-10 engine
Nord 1102 Noralpha II
proposed 6Q-11 model, never built
1101 modified with the Potez 6Dba engine, one built
SFERMA-Nord 1110 Noralpha-Astazou
two 1101s modified as testbeds for the early Turbomeca Astazou tubroprop
By me All photos me too unless otherwise stated, copyrighted
While (strictly) military aircraft are not something I usually cover on this blog, after reviewing some of my photos from a recent trip to Italy, I’ve decided I could make a slight exception – just this once :D. Namely, back in mid-November I had the opportunity to visit Thiene Airfield (ICAO: LIDH) in Northern Italy, where four colleagues and myself were scheduled to take the standard “ICAO English Proficiency” test required for the issue of our CPL licenses. And while the doom, gloom and torrential rain forecast the day before had seemingly precluded any effective outside photography, I’d nevertheless packed my 10-pound camera bag in the hope that I may stumble onto something interesting nonetheless… 🙂
A quaint grass strip situated a few miles north of the historic city of Vicenza, Thiene did indeed have a party piece for me, one I’d homed in on even from the airfield’s access road: a beautifully preserved F-104 Starfighter, the first one I’ve ever seen in person! 🙂 Its air superiority gray blending in perfectly with the dull, low overcast, its fuselage gleaming in the rain, it had immediately grabbed my attention – and after a short round of international diplomacy, the very kind airfield staff had allowed me to get up close and whip out my anti-aircraft Canon :D.
Standing in front of MM6914, it is hard to appreciate and even imagine the impact the Starfighter’s shape had in when it had first flown in 1954. WW2 had ended just nine years ago, propliners were still plying the skies, and even the world’s major air forces still had piston-engine fighters in frontline service… and then, out of nowhere, this needle-sharp, razor-winged jet-propelled missile appears, thundering past at twice the speed of sound and altitudes three times higher than any civil aircraft could reach. In a world still inspired by Buck Rogers and Flash Gordon, it wasn’t really hard to see how the 104 got its name :).
And yet even today, 56 years after its maiden flight, the Starfighter’s stellar performance – pun intended 😀 – remains impressive. So impressive in fact that the type had – despite all its faults – remained in service until 2004, last flying with the inimitable Italian Air Force. One of these fascinating aircraft is our MM6914, whose full name drags out to Aeritalia F-104S ASA-M Starfighter – or in plain English, a license-built Italian-spec Starfighter that had received a weapons systems upgrade (the ASA-M bit) sometime during its service life :). The most capable of all the Starfighter marks, many of these aircraft had managed to evade the scrapman’s axe and are now adding their bit to the beautiful Italian landscape… 🙂
Like many Spitfire enthusiasts, over the years I had gone through all the “fan-boy” motions: I’ve watched the movies, read the books, saw the photos… collected a bit of memorabilia even, the lot. But, as is often the case with these things, my involvement with the Spit had always stopped short of actually seeing a real, flying example. Sure, I’ve seen one in a museum – an ex-Yugoslav Mk.Vb in Belgrade’s Aeronautical Museum – but static, toy-like and lifeless, its beautiful Merlin silent, it just didn’t cut it at all.
Determined for years to right that wrong, last Saturday (26 June) I sat in the car and set off for La Comina airfield in Northern Italy. Just a few miles south of Aviano airbase, this small grass field – one of the oldest in the country – was the venue for the La Comina 100 airshow, part of a series of shows across the width and breadth of Italy, celebrating its first century of (practical :D) aviation. On this occasion, the aircraft line-up had included a mouth-watering selection of precious warbirds, including my “target for the day”, my first ever flying Spitfire! 🙂
Owned by the Jacquard Collection of France, F-AZJS – a post-war photo-reconnaissance PR.19 – is perhaps not the most exotic Spitfire around, but it is among the very few surviving examples of what some call the most capable Spitfire mark of them all. The last of the land-based Spitfires – powered by the monstrous 2035 HP Rolls-Royce Griffon 65 borrowed from the 1944-vintage Mk.XIV – the light, unarmed PR.19 can zip along at a fantastic 740 km/h, along the way touching altitudes in excess of 50,000 ft; heights that put most modern civil jets to shame! 🙂
That day though, F-AZJS would (thankfully) be touching just – 500 ft :D. Already excited out of my skin – and set and ready to experience the grace, power and charisma of the immortal Spit – I had readied the camera and waited…
As an added bonus feature – and in the interest of serving a balanced dose of irony 😀 – I’ve also decided to include a few shots of the unique Fiat G.59-4B two-seater that had also appeared at the show, currently the only flying example in existence. Though it outwardly looks like a bastard cross between a Spitfire, Bf.109 and Yak-1, it is actually based on the curvy Fiat G.55 Centauro, hailed by many as the best Italian wartime fighter. Powered by a 1475 HP Fiat Tifone inverted V12 – a license-built version of the Daimler-Benz DB 605A-1 – it had proved to be a formidable opponent, taking on Spitfires and Mustangs without a second thought. Stunningly maneuverable – but slightly under-armed – the G.55 had some notable combat successes, but their low numbers meant that the type couldn’t make much of a dent in Allied air fleets.
An advanced design that was ahead of its time in a number of respects, the G.55 was – like the Bf.108 previously featured here – returned to production following the end of WW2. However, again like the Bf.108, it soon started facing a serious shortage of engines, with the stockpiles of WW2-vintage Tifones – and even imported DB 605s – dwindling fast. In a bid to keep the production lines open, the design team started looking for a replacement engine – but, unlike with the Bf.108, their choices were very limited. The only realistic option in the required power range was none other than – the RR Merlin :D.
Re-designated as the G.59, the new aircraft was comparatively successful, though was in the end built only in modest numbers (with almost half intended for Argentina and Syria, the type’s only foreign customers). Two versions were produced, the single-seat A models and the two seat Bs, to whose last batch our example – I-MRSV – belongs…
By me Photos me too unless otherwise indicated, copyrighted
With a click and unwilling grunt, the imposing four blade prop slowly catches the air. Protesting now with an ever-louder series of coughs and bangs, the big engine comes to life, spewing clouds of white smoke to show its displeasure at being so rudely awoken. The characteristic whiff of petrol and grease spreads through the air as the whine of the huge supercharger builds up, almost inaudible beneath the increasing bass roar of nine cylinders. Spewing drops of oil from the single exhaust pipe, the unruly engine looks and sounds like it can barely hold itself together, like it might fall apart any second without warning.
And with its belly already smeared in oil, its fuselage stained by exhaust and its metal skin shuddering in the propwash, the big biplane doesn’t inspire much confidence in the casual observer. And yet, for all its farmyard machinery appearance, this beautifully ugly airplane still has an obvious air of competence, durability and purposefulness around it… but that really should not be very surprising; for after all it is one of aviation’s greatest legends – the fantastically charismatic, and damn near indestructible, Antonov An-2 :).
Lumbering unhurriedly along in the lower levels – comically too in any stiff headwind – it’s hard to see at first what made the Anushka into one of the world’s great aircraft. As sophisticated as a telegraph pole, this noisy, ungainly, uneconomical biplane is a stereotypical anachronism, looked at by many with the same mix of fondness and patronization as an exhibit in a WW1 museum. Sort of like “you gave it your best shot, but it now time to move on to newer things”…
Yet, despite all its apparent crudeness, the An-2 is a true masterpiece of design. Understated, it has gone quietly about its business for more than 60 years, never blowing its trumpet even though it had a million reasons to do so. From deserts to polar wastelands, often operating in conditions that would shame most other designs, the An-2 has soldiered on without fuss or pomp, setting records for machine and man achievements that, more than anything else, show what aviation is really about :).
And therein lies the answer to the main question: what makes the An-2 great is the same thing that made the DC-3/C-47, the C-130 Hercules, and the Twin Otter great – the ability and capability to do anything and everything, to be adapted to every required role and do it brilliantly. And like the DC-3, C-130 and DHC-6, it has outlived all of its intended replacements, finding none equal even in today’s world of glass cockpits, carbon fiber and super-efficient jet engines…
But to find out the story of this amazing aircraft, to see what makes it tick so well, we first have to turn to the birds and the bees… and the badgers, mosquitoes, bears, goats and whatnot else the Soviet Ministry of Agriculture and Forestry had to deal with in the immediate aftermath of WW2. Faced again with the age-old problems of administering the USSR’s vast open areas, in 1947 the Ministry had issued a specification outlining a simple and dependable utility aircraft that could be used for this purpose. Required from the outset to operate pretty much out of open fields far from large population centers, the new aircraft had to have a demanding mixture of characteristics, not least of which was full rough-terrain STOL capability. But more critically, it also had to be almost completely self-sufficient once on the ground, and uncomplicated and intuitive enough to be maintained with a minimum of basic equipment by whatever crews could be scraped together from the local populace.
In addition, the aircraft had to be easily adaptable to a variety of secondary roles – one of the most important being cropdusting – and be easy and forgiving to fly in all conditions. And it had to be able to do all of this in a bewildering range of climates found across the former USSR, from the hot deserts and steppes of Asia, to the vast taiga of Siberia and the snow and ice of the Arctic circle…
In the spirit and general optimism surrounding the new aeronautical technologies developed and refined during WW2 – jet engines, advanced liquid-cooled V-block pistons, monoplanes, retractable gear – Oleg Antonov’s solution to this challenging requirement took a number of people by surprise. Fresh from the Yakovlev design bureau, this talented engineer – responsible in no small part for the superlative Yak-3 fighter – had quickly gained a reputation for innovation, thoroughness, and not a small amount of design boldness. So it came as a bit of shock that, tackling such a stimulative specification, he had only managed to come up with a lumbering, antiquated biplane – a design considered by many to be outdated before it had even flown…
However, like with every aircraft he had designed, Antonov had put a lot of thought into what the future An-2 should really be. Already an experienced designer, he was well aware of the problems the USSR’s great, sparsely populated open ranges presented. He had also observed the sometimes crippling effects the Russian winter – and generally the hard going – had on the sophisticated German fighters of WW2, and how the comparatively simpler Soviet aircraft seemed to suffer a great deal less, happily flying when their counterparts were grounded for days on end.
With this in mind, it soon became apparent to Antonov that these new technologies the world was on about would simply not cut it in the Soviet backwoods (at least not just yet). Leaving aside the extremes of the weather, where would one find a qualified mechanic for a liquid-cooled V12 in a remote village in Siberia or on the wind-swept plains of Kazakhstan? Or the workshops and materials to repair a high-loading monoplane wing or a retractable gear leg when you’re operating out of a forest clearing on the rim of the Arctic circle?
The way forward therefore was backwards. What Antonov saw as the key to making the An-2 work – and with 20/20 hindsight we can agree he was spot on – was to use older tried-and-tested technologies to make the aircraft so dependable and simple that there wouldn’t be anything on it to break… and if it did, it could be fixed with a spanner and some tape.
But the resulting design – first flying, to considerable chaffing, on 31 August 1947 – was anything but a mere collection of bits the Wright brothers could have used; indeed, the An-2 still stands today as a shining example of intelligent, purpose-built and minimalistic design. Far from being just another biplane, it is brimming with solutions and ideas that show just how much thought, planning and old-fashioned common sense went into its design…
2. Go Ugly Early:
For starters, there’s its trademark biplane layout. While this does pay a high price in drag – with the An-2 pegged at just 140 knots, despite the 1000 HP up front – it reaps huge benefits in the low-end of the speed range. The large wing area – 71.5 m2 (770 ft2) – means that enough lift can be generated down to very low speeds, which, combined with its clever airfoil shape, gives the An-2 a comically low minimum flight speed of just 49 knots! 😀 (for reference, that’s also the clean configuration stall speed of the Cessna 172)
Slowing down further from this speed, the unknowing pilot would find himself/herself quite surprised by the An-2’s stubborn refusal to stall (though I feel the novice pilot would be very appreciative of this feature 🙂 ). Indeed, should the aircraft for whatever reason find itself at such a low speed in level flight, the spring-loaded leading edge slats on the upper wing would extend, keeping the airflow glued to the wing, and the whole thing would simply descend gracefully under full control at a “parachutists rate” and just 30 knots of forward speed :D. The big, chunky landing gear would absorb the impact and, more often than not, the crew would just walk away with very little damage to the aircraft… as a consequence the aircraft – uniquely – has no concrete published stall speed in The Book* (and I’ve checked this).
* however, the whole stalling issue is a minefield. The popular idea is that the stall is caused by a lack of speed. This is not so – a stall is caused by a disruption to the airflow around the wing. Low speed does indeed cause a stall – because to maintain level flight the aircraft has to continually increase the Angle of Attack as it slows down, until it becomes so large that the airflow separates from the upper surface of the wing and lift is lost. However, you can stall an aircraft going at full speed, in a climb, dive, turn, loop, you name it. You just have to pull on the commands with such force that the aircraft rotates so quickly in a short period of time that airflow breaks off the upper surface. So the An-2 can stall – but in level flight its aerodynamics allow it to be flown in such a manner that the airflow sticks to the wing at all times.
But its low speed capability is best evident in the takeoff run, which is a spectacle that can best be described as – interesting. On most aircraft, the takeoff is a visually striking event, with the charge down the runway, the purposeful rotation and powerful climb-out… the An-2 though just slowly accelerates – with the inevitable misfire or two – and after two hundred meters starts slowly going up, no rotation, and rumbles away like it’s not in any sort of hurry…
The third factor contributing to the An-2’s low speed prowess is the wing loading – or simply put, how much weight does each unit of wing area have to support in flight. Normally, this is used as a measure of aircraft handling, with the lower the value, the more docile and easier to fly the aircraft is.
And despite looking like a jolly mass of airplane, the An-2 weighs just 5.5 tons at MTOW, which is spread over the aforementioned 71.5 m2 of wing area. This gives a wing loading of 77 kg/m2, which compares very favorably to the 87 kg/m2 of the Cessna 182T – and is not that far above the the 172R’s loading of 70 kg/m2, which pretty much ticks the “easy handling” box :).
Another interesting side-effect of the this biplane configuration may not be readily apparent to us at our big airports, but is probably much appreciated in the areas where the An-2 is “at home” – namely, neither wing has a very large span, which means the Anushka can happily operate in tight, confined areas outside normal airports and airfields. The comparatively narrow main gear span too means that its turning circle is quite small (for an aircraft its size anyway), which helps in maneuvering on the ground.
The engines too were given a good deal of thought, even though Antonov was not really spoiled for choice in this department. Jets were still just getting off the ground, it’d be years before the first turboprops left the drawing boards, and V-blocks were just too complicated and frail for a lifetime of torture – and dubious maintenance practices – they’d be subjected to. So, the only remaining option was to go radial :).
The first choice, beginning the An-2’s “third cousin removed” relationship with Wright Engines of the US, fell on the Shvetsov ASh-21 (or more accurately, AŠ-21), a 7-cyl radial producing about 780 HP. In essence, this was a single-row version of the company’s twin-row 14-cyl ASh-82, an engine based on the knowledge, experience – and a fair number of structural parts – of the M-25, a Soviet license-built Wright R-1820 Cylcone 9, one of the great radials of WW2. Finding out that the An-2 prototypes could do with a bit more poke, the engine was changed on the production versions to the ASh-62, which was – again – a distant relation of the R-1820, being based on the same M-25. Quite a bit more potent than both the ASh-21 and the Cyclone, the ASh-62 was able to produce 1000 HP out of nine cylinders, which was deemed enough for the new aircraft.
While selection of the ASh-62 would have been a foregone conclusion based on its rated power alone, it did have several other beneficial – and I’m inclined to believe intended – consequences, which would have fit right in with Oleg Antonov’s vision for the An-2. Like the Cyclone on which they are based, the ASh-62 and 82 were as common as trees, powering a number of famous aircraft such as the Polikarpov I-16, the Lisunov Li-2, Tupolev Tu-2 and all the Lavochkin fighters – aircraft common to virtually every corner of the USSR. Indeed, both engines were intended to remain in widespread service for years to come, so finding someone qualified to repair one was sufficiently likely even in the most remote of airfields.
And despite the fact that the ASh-62 and 82 were different engines only partially based on the Cyclone, they still carried part of the R-1820‘s DNA – or more specifically, its technologies and lessons learned, most of which the hard way. And when it’s chosen to power the B-17, DC-2, DC-3, the Dauntless divebomber, the Wildcat and many others, it definitely must be good :D.
3. The Devil is in the Details:
But if anything, it was the little things that really showed how much thought was invested into the basic An-2 concept. The cockpit for example is very airy and roomy, while extensive glazing provides a good view in all directions – something especially important if you were slated to spend most of your life rumbling at low levels, never mind the slow speed.
Out back, the main cabin is similarly utilitarian – but for the An-2, this is a compliment if anything :). Almost perfectly rectangular in cross-section, it can be – and was 😀 – adapted to countless applications, while its comparatively high floor strength means you can load up a lot of cargo without undue worry. Other interesting touches also include cabin walls lined with glass-wool to reduce noise – which can be considerable, it must be said – and, on some passenger models, even a toilet!
Underneath the skin though, away from criticizing eyes, the An-2 starts to show off its true colors – starts to show off just how cleverly it was really designed. For example:
despite its dated biplane format – which would have probably suggested otherwise – the An-2 is built almost entirely of metal. The entire fuselage structure is a stressed-skin semi-monocoque – as seen on passenger airliners – rather than the simple frame used on similar aircraft (including many light aircraft of all sorts still produced today). As mentioned in a previous post, in the semi-monocoque construction the loads exerted on the fuselage in flight are spread between both the basic structure and its metal shell. This was a boon for pressurized airliners, because it provided a light, yet durable and strong airframe, which could easily absorb the stress created by pressurization. In the unpressurized An-2’s case, this structure can absorb significant forces – for example during a hard landing – and distribute them evenly over the entire airframe (including the skin), reducing stress on specific components
on the other hand, all the flying controls – rudder, elevators, flaps, ailerons – as well as the entire wing aft of the main spar, were – fabric covered. An odd pair with the advanced metal structure, this common WW2 solution was (cleverly) chosen for practical reasons: the “hybrid” wing allowed the leading edge – and ergo the spar, the wing’s most important element – to be protected from frontal impact. At the same time, any damage caused by debris thrown at the wing and the controls by the wheels – which was sure to happen on a daily basis – would be easy and inexpensive to repair out in the field (one of the reasons you may often see An-2s with control surfaces painted in a scheme completely different from the rest of the aircraft)
but the feature that shows most of all just how pessimistic – or realistic – Oleg Antonov was about the ground infrastructure the An-2 would have available is the refueling system. Nothing as old-fashioned as a man climbing on a ladder and pouring fuel into the tanks, the Anushka instead uses a powerful on-board pump that draws fuel from any fuel canister and flushes it into the tanks :). The whole procedure consists in simply rolling a barrel of fuel up the aircraft, dropping a special hose into the barrel and turning the pump on – and presto!
Another interesting feature on the An-2 is its use of a pneumatic system instead of a hydraulic one normally used in the West. Common to virtually all Soviet light aircraft before or since, the pneumatic system works and functions exactly like a hydraulic one, but uses air as the working medium instead of hydraulic fluid. While this may appear to be an insignificant change – and even a complication – it does have a number of advantages when used in the conditions the An-2 was designed for:
first and foremost is its lower weight when compared to the hydraulic system. Because the air in the installations is at very high pressure, smaller diameter pipes are necessary to produce the same force, which drives the overall weight of the system down
the system can also be easily replenished. The An-2 for example has an air line fitted to a special compressor in the engine bay, which can refill all of its pneumatic systems – the brakes, tailwheel lock, shock-absorbers and even the tires – which are normally charged from an 8 liter compressed air cylinder. This has a raft of benefits, the greatest being that it negates the need to carry reserve hydraulic liquid around. Also, the pneumatic system is replenished without human intervention – apart from opening the air line – which also means one time-consuming task less for the mechanics
the last major benefit is that air is much more forgiving that hydraulic fluid (which is usually a special synthetic oil) in temperature ranges as diverse as the ones the An-2 would see – especially at low temperatures, where the viscosity of the oil increases and the system loses power (not to mention the possibility of the oil freezing)
The pneumatic system does have some disadvantages however, the biggest being the inherent hazards of handling compressed air cylinders – but this pretty much applies to any compressed gas or liquid. The other major disadvantage is that the pneumatic system is much more coarse when it comes to metering out the force to be applied, which can lead to imprecise system performance and usage. However, this is only a small setback as far as the An-2 is concerned: considering its most important pneumatic system – the brakes – you either have to stop so quickly that just slam the brakes full on, or you have a long enough runway on which the An-2’s STOL characteristics mean that stopping distance isn’t an issue :D.
4. Revenge of the Write-Offs:
Naturally, with a design as thought-out as this one, it was only a matter of time before the humble Anushka outgrew its original specification – and before Oleg Antonov started catching breath for the last laugh. And while transport and cropdusting had indeed remained among its primary missions even to this day, the aircraft’s durability, adaptability and stunning range of capability had immediately lent it to a host of other – and often diametrically opposed – duties.
To cater for these, a number of versions and sub-versions were developed, which progressively grew in number until only the most fastidious An-2 fans could even being to count them all up. Further complicating the matter is that in 1960, the majority of An-2 production was moved from the Ukraine to PZL-Mielec in Poland (along with production of the ASh-62 to PZL-Kalisz), which would eventually cause some linguistic problems as aircraft with different roles were allocated the same designations. And cataloging Chinese production – where it was known as the Shijiazhuang/Nanchang Y-5 – is a similarly herculean task. However, in the interests of a balanced post, I’ll post a link to the full list on Wikipedia (and for once, a list made from a reliable source) and single out a couple of the most interesting ones:
An-2A – developed to intercept US reconnaissance balloons (now there’s a novel usage), this interesting version was equipped with a dorsal gun turret and a more powerful, turbocharged version of the ASh-62 engine
An-2E – two ekranoplan (wing-in-ground-effect) versions sharing the same designation. Though Boeing had touted loudly a few years ago about its innovative Pelican concept – which would have been a massive transporter “flying” a few feet above the water – the original technology was developed in the USSR in the 60s by famous scientist Rostislav Alekseyev, who had also developed the Alekseyev KM, a humongous 10-engine ekranoplan that even today remains one of the largest flying objects ever built… despite the fact that it’s currently at the bottom of the Caspian Sea
An-2F – among the three versions to use this designation, by far the most fascinating was a proposed VTOL version, with an AM-9 turbojet in the rear fuselage
An-2PD-5 – an executive version provided with a bar and pantry 😀
An-2PRTV – modified as a TV broadcast relay for the Polish Radio and Television Company
An-2RT – a single An-2 converted to receive and record telemetry from test missiles
What can be considered to be the ultimate development of the An-2 though – a development that actually worked, sort of – was saved for last: the An-3. Re-engined in the 80s with a 1433 HP Glushenkov TVD-20 turboprop, the An-3 was intended as a cheap, off-the-shelf replacement for the vast fleets of ageing An-2SKh cropdusters, as well an alternative to the ultimately failed Myasischev M-15 Belphegor, the world’s only jet powered cropduster :). Fitted also with a squared-off vertical stabilizer and a thoroughly updated and modernized cockpit, the An-3 prototypes had in a short time set an impressive six payload-to-altitude world records for their class – but in the end, with the breakup of the USSR looming very close, these had counted for very little and the An-3 became just another commercial failure. The design resurfaced again in the mid-90s as the An-3T, but this time as a retrofit of existing, surplus low-time An-2s – with just marginally more success…
In the end though, the above list generally an academic affair, since the majority of An-2 versions could be adapted to do everything the other ones could. So you had passenger versions dropping skydivers, cropdusters hauling cargo, transports cropdusting… some towed gliders (A.net photo), some flew to the poles (A.net photo), some became firebombers (A.net photo)… some became lorries (A.net photo) :D… generally, the list would go on for awhile.
And then there were the Croatian Air Force examples :). With the start of the ex-Yugoslav civil wars in 1991, the nascent CroAF, faced with a complete lack of aircraft, had decided to turn everything with wings into a combat aircraft. This may seem like an exaggeration, but Air Tractors fitted with a gunsight and bomb racks, UTVA-75 trainers with shoulder-held rocket launchers under the wings and Cessna 172s dropping hand grenades from the cockpit were a common sight in the early days of the war. Among them were numbers of An-2s which were mostly used as “heavy bombers”, armed with so-called “boiler bombs” – gas cylinders filled with explosives and anything that could act as shrapnel: forks, razor blades, knives… – dropped out of open doors by the crews. Operating mostly during the Siege of Vukovar, by day and night, these aircraft would fly low-level attack and resupply missions in the face of formidable Yugoslav SA-6 surface-to-air missiles and defending MiG-21 and 29 fighters. In what is perhaps the greatest irony associated with the An-2, they were virtually invulnerable in this role! 😀 Intentionally flying at barely 40-50 knots, they were so slow that they ended up below the detection threshold of every fire control radar, which then wouldn’t even show their echo on the screen. The defending fighters had an even greater problem, flying at speeds of 200-300 knots and trying to intercept a target moving slower then a car at tree-top height. However, when the Yugoslav National Army modified the SA-6’s radar to lower the detection threshold, the An-2s started suffering heavy losses and were withdrawn from the role.
All in all, not a bad showing for an “ancient, rustic biplane” :). And while time had ran the An-2 over as a commercial transport long ago – it not being the cheapest aircraft to operate, and Western certification being nigh impossible to obtain – they remained in regular production in Poland up till 1991, by which time many more modern designs came and went. Indeed, low-key production from spares continued until 2001, making for an enviable production run of 54 years – beaten only by the Hercules and the record-holding Beech Bonanza (coincidentally first flying the same year as the An-2 🙂 ). During that time more than 18,000 were produced – with some estimates as high as 20,000 – although the true number may never be known without accurate figures from license (and off-license) production in China.
But what really puts the shine on these numbers – what I’m tempted to say even eclipses the production achievements of any other aircraft – is that the An-2 went through an entire half century fundamentally unchanged from the first post-war versions. There were no new engines, no avionics upgrades, no lavish new features or wild performance increases – just the simple, basic, utilitarian 40s design, rumbling calmly about its business for 60 years in conditions and situations few, if any, other aircraft will see in their lifetime.
And this, if anything else, is a great, lasting testament to the brilliance of its design and the genius of the men who had worked on it :). Anachronism? Hardly!
6. Specifications, references and more photos:
Given the large disparity in performance figures found in various sources, I tried to stick to the ones that appeared to know what they’re talking about :D. One such website – an excellent resource for all things An-2 – is An-2 Flyers, from which I’ve taken most of the specs (unfortunately, due to the design of their site, I’m unable to link to the performance page directly, but you can find the button to it near the bottom on the left hand side of the page).
Having become bored of my previous desktop wallpaper, I decided to rummage once more through my photo database in search of a suitable replacement. And being currently under the influence of pre- and post-WW2 aviation – as evidenced by my last two Rare Aircraft posts 😀 – I was looking for a technically imperfect, “realistic” photo of some aircraft of that era, which I would then artificially age in Photoshop and hopefully end up with something that could pass as “authentic”. Having drifted off course quite badly, I ended up with a Tu-154, but the process gave me a swell idea for a new post to break the monotony (and with it snowing like mad – again – the monotony was sure to continue)… 🙂
What I wanted to do was create something of a “historical East Block photo report”, using only my own photos and manipulating them to make more-or-less believable representations of photos that could have been taken in the periods concerned. Though I’ve sorted the images according to the aircraft type’s year of first flight (indicated in the parentheses), they actually represent the years when that type was at its heyday, that is, the years when it could be seen in greatest numbers. To this end, I stuck to images with neutral backgrounds and without anything modern in view, and “aged” them to reflect also on the various types of cameras that could have been used; so a photo taken in 1980 may be B&W, while a photo from the early 70s may be in faint colors…
The dead giveaways shattering the illusion are the modern registrations – as well as some obvious faults in my aging work – but for viewing pleasure, I think I’ve hit the mark quite nicely :).
When the Messerschmitt Bf.108 first appeared on the European general aviation scene in the mid-30s, it had created something of a “Porsche moment”: here was a small and light tourer, astoundingly fast yet relatively low powered, agile but quite docile, so left-field in design that it had shocked in the same measure it had fascinated. More than anything else, it had finally dispelled most of the skepticism and antagonism toward the low-wing monoplane configuration for light aircraft (at least in Germany), showing just what could be done with this novel idea once you’ve put your mind to it.
Pretty soon, this success had kicked off something of a “VW Beetle moment” :D. Seeing that the mentioned configuration does indeed work – and rather well at that – several manufacturers began seeing its potential to replace the lumbering open-cockpit biplanes then used for common day-to-day operations. What was needed here was a simple, cheap, robust and versatile no-frills machine that would efficiently go about its training and liaison duties, while still retaining that quantum leap in performance (and comfort!) over existing aircraft.
At the Arado works, the engineers, having too caught the bug, had rolled up their sleeves and set to work. The end result, intended like the Bf.108 to combine these new technologies into a single purpose-built design, was the diminutive, unimposing – and today unjustly forgotten – Ar 79…
A very advanced design for its time – just a notch below the technical level of the production-standard Bf.108 – the Ar 79 was somewhat of a logical outcome for Arado. An innovative company that is today much overshadowed by the more famous names of 30s/40s German aviation, it had been around in one form or another since WW1, but rose to prominence as an independent manufacturer in 1924 when it was bought by a Fokker engineer, Mr. Heinrich Lübbe. While you’ll be hard pressed to find someone who’s heard of him, Mr. Lübbe has nevertheless left a lasting mark on military aviation as the inventor of the mechanical interrupter gear that had allowed machine guns to fire harmlessly through the propeller disc without clipping the blades. He had also left a significant mark on Yugoslav aviation, I was amazed to find out, when in the same 1924 he had opened an Arado subsidiary in Yugoslavia called – Ikarus! 😀
Under various design heads, including fellow Fokker veteran Walter Rethel – who would later go on to become the chief engineer on the Bf.109 – the young company had soon gained a solid reputation in Germany for its advanced, mostly metal light biplane fighters and trainers. Indeed, the company’s Ar 64 and Ar 68 were among the first combat aircraft produced in Germany after the Versailles Treaty was… ignored, and were the first front-line fighter aircraft to equip the new Luftwaffe. The majority of its pilots too were already familiar with Arado, having trained – in secrecy, under the guise of civilian aeroclubs – on the widespread civilian Ar 66 biplane trainer.
Despite these successes however, by the time the Luftwaffe was firmly on its feet Arado was already beginning to suffer from a slight case of “Messerschmittitis”. The animosity of several high-ranking German officials (most notably Erhard Milch) towards Willy Messerschmitt is well documented, having been a significant factor in undermining Bayerische Flugzeugwerke during the pre-war years, despite the demonstrated ingenuity – and outright superiority – of several Messerschmitt designs. Heinrich Lübbe’s refusal to join the Nazi Party had had a similar effect, though in the end far more reaching: with the Party’s patience finally running out in 1936, Lübbe was removed from his position and Arado promptly nationalized.
With the constraints of personal vendettas now removed through an unfortunate turn of events, Arado’s designs had finally received a fair fighting chance. This, and the accelerated production and development spurred by WW2, had seen the introduction into service of several notable Arado aircraft, including the Ar 96tandem two-seater (which would very soon become the standard Luftwaffe advanced trainer), the Ar 196 floatplane found virtually on every German ship, the innovative Ar 232 heavy transport, and finally the ground-breaking Ar 234 ‘Blitz’, the world’s first jet bomber. An unorthodox masterpiece of design, it’s legacy and impact are today pretty much the only things keeping the Arado name from sinking into total mainstream obscurity…
The Arado company however had already been sunk long ago by the decision to nationalize, for with the collapse of German industry at the end of WW2, the company was shot down with it. While a vast majority of companies large and small were able to somehow stay afloat until the mass integration into huge consortiums in the 60s – Messerschmitt for example by producing sewing machines and the odd KE 175/200 bubble car – Arado was immediately declared bankrupt and written off once and for all…
2. A Diet 108:
Back in more successful pre-war times, the Ar 79 had – as mentioned – represented the company’s attempt to design a cheap & cheerful modern light aircraft that would lend itself well to common, non-utility tasks. Unusually, despite it being 1938, it was designed for the civil market only and very few were actually used in military roles – odd given the many aircraft of all types then being pressed into Luftwaffe service (more so when you consider that a majority of early German transports and bombers were designs that had started out as passenger aircraft for Lufthansa).
At a glance from a distance, the Ar 79 looked very much like a Bf.108 – and keeping in mind that there is only a number ways you can design a low-wing monoplane taildragger, we can’t hold that against it. Up close however, there were some notable differences, the biggest being the odd vertical stabilizer. Introduced on the Ar 68 in 1934, it would become the trademark of all subsequent Arado piston singles – however, I’ve not been able to find out exactly what advantages did the design give. But – using a bit of Eyeball Mk.I extrapolation – its near-vertical leading edge reminds me of the stabilizers on Mooneys, which are designed to give better control response in stall and near-stall situations. And given that most Arado singles were trainers likely to be spending quite some time there, it does sound plausible.
Weighing in at just 760 kg MTOW – round about your average Cessna 150 – the Ar 79 did not really need much power, making do with a 105 HP Hirth HM 504A-2 inverted inline four cyl turning a two-blade fixed pitch prop – noticeably less exciting than the Bf.108’s inverted V8 :D. However, its clean lines and – unusually for such a small aircraft – retractable main gear meant it could squeeze a lot out of the power available, with a respectable cruise speed of 110 kn and a service ceiling of about 18,000 ft – all while burning just 10 l of avgas per 100 km. If we convert that to the more usual gallons per hour, we get a very low 5.2 (US) GPH at 110 kts…
So far, so Bf.108-ish. However, once you look below the skin – or at it for that matter – things start to go awry. Unlike the all-metal 108, the Ar 79 was a somewhat unusual mix of metal, wood and fabric, everything from the modern to the utterly conventional. Starting out back, the rear fuselage was an advanced magnesium alloy (!) (or “electron casting”) monocoque structure. In this type of construction, pioneered during the first decade of flight, the skin itself is the only load-bearing element – it is the only thing making up the structure, without any form of internal support. Contrary to what I had assumed, this had made the Ar 79’s rear end very light, much lighter than it would have been had more commonplace solutions been used. In addition, this type of construction had also paid off in simplicity and strength, with its oval shape spreading the load evenly around the fuselage and the (predominantly) one-piece structure removing the need for rivets, joints, welds or other such structural weak points (in later years, in an effort to reduce weight when applied to larger aircraft, this structure would evolve into what’s known as the semi-monocoque, which combines the load-bearing skin with an internal bracing frame, permitting the metal to be thinner and thus lighter, while still keeping many of the monocoque‘s qualities. In this form it has been used on airliners since the 50s, where it’s load bearing characteristics have been put to good use at battling the stress of pressurization 🙂 ).
EDIT: I would also like to extend my sincere thanks to Mr. Adolf Jaeger for correcting my erroneous assumption that this type of monocoque structure would be slightly heavier than conventional constructions.
Progressing forward however, things were starting to become more agricultural. The forward fuselage was a simple welded steel tube cage covered with fabric, while the wing – single spar, like the 108, but without slats and flaps – was a plywood affair again covered with fabric (and don’t laugh at the plywood! Just ask De Havilland and it’s Mosquito light bomber about what could be done with that fascinating material 🙂 ). The only other bit of metal up front was the cowling covering the engine…
Everything considered, one could deduce that the Ar 79 had quite an interesting weight distribution: almost evenly balanced fore and aft, something rare in most aircraft :). This would have located the center of gravity somewhat more aft than normally found on similar aircraft – not that far aft that it became tricky to fly, but enough to make it stable and maneuverable in equal measure. And being otherwise fully aerobatic – equipped with an aerobatic carburettor, permitting inverted flight – this would have made the Ar 79 quite agile :).
3. Fuel for thought:
While from today’s perspective the performance specs may seem a bit average – they’re hardly better than those of the Cessna 152 Aerobat (apart from the acro carburettor and retractable gear) – in its time the Ar 79 was quite a good performer and, like the Bf.108, was used on its fair share of record-breaking flights. The more “usual” ones were the 1000 and 2000 km solo class speeds records of 229.04 km/h (123.67 kn) and 227.028 km/h (122.58 kn) respectively, both set in 1938. While all very good for a light 105 HP aircraft, they were not nearly in the same league as what was done between 29 and 31 December of the same year…
It had always been said that the true test of an aircraft was a long distance record flight. The Arado team had apparently taken this a bit close to heart, for when they rolled the above pictured D-EHCR back into the hangar, they decided they could just up its fuel capacity a bit… now, I couldn’t find the exact capacity of the standard tanks, but with a range of 553 NM at 110 kn and 5.2 GPH, it works out to 26 gallons, or 99 liters. This was felt to be somewhat inadequate, so what the engineers did was bolt a jettisonable 106 liter fuel tank under the fuselage and screw in a whopping 520 liter tank behind the cabin. In total, this gave 725 liters (!) to burn, which – at avgas’ standard specific gravity of 0.7 kg/l – weighed in at 508 kg and was 48 kg more than the empty weight of the plane :D.
This was deemed enough to give good record-breaking range and was put to good use between 29 and 31 December when a two man crew flew non-stop from Benghazi in Libya to Gaya in India – a distance of 6,303 km (3403 NM)! At an average cruise speed of 160 km/h (86 kn) that would have taken a tad more than 39 hours, quite a feat for an understated two-seat trainer groaning under its own weight in fuel 🙂 (though this fuel to weight ratio would certainly not be unique; the Rutan Voyager, which flew non-stop around the world in 1984 without refuelling, could carry more than 3 times its weight in avgas!).
4. From here to… obscurity?
Apart from its record-breaking flights – flown mostly by the second prototype, which crashed in India about two months into 1939 – the Ar 79’s regular service life was quite uneventful. It’s versions were even scantier than those of the Bf.108, with only the Ar 79B, Ar 79D and Ar79E seeing the light of day – and these differed only in minor equipment changes. Some sources do state that the production models were fitted with Hirth HM 500A1 engines, rated at the same 105 HP, and that the 504 was used on the prototypes only.
But, despite its flying qualities and proven performance over longer distances, in the end the Ar 79 was not really a sales success (though WW2 had much to do with it, the civilian general aviation sector virtually disappearing overnight): not counting the two prototypes, only 48 production models were built when production ceased after just three years, in 1941.
Interestingly though, the basic design was still considered advanced in the 50s, and in East Germany plans were made in 1952 to return the aircraft into production in an all-metal form; however, the 17 July 1953 uprising had put an end to that for good. West Germany too had similar ideas, when in 1957 the Ar 79 was used as the basis for the all-metal Blume Bl 500, designed and built the man behind the original Ar 79, Walter Blume :). It’s high price of DEM 63,000 however meant the entire project never made it beyond the two prototypes…
Today, only one Ar 79 is known to have survived – thanks once more to the sterling efforts of Lufthansa’s historic flight, the Deutsche Lufthansa Berlin Stiftung. D-EMVT – an Ar 79B-1 and the next-to-last Ar 79 built – was meticulously restored in 1996 and kept in flying condition up till 2001, when it was put up as a permanent exhibit in the Deutsches Technikmuseum in Berlin, where it now hangs out for most of its days :).
Given that the Internet is not awash with precise specifications of obscure planes, I naturally had some issues in determining which sets of performance numbers to believe. In the end, I opted for the most reliable source – Lufthansa 🙂 – which gave the specs on the most widespread Ar 79, the B model:
Engine: Hirth HM 500A-1, 105 HP
Stall speed: 78 km/h (42 kn)
Cruise speed: 205 km/h (111 kn)
Maximum speed: 230 km/h (124 kn)
Range: 1024 km (553 NM)
Ceiling: 4,500 m (14,760 ft)**
Length: 7.6 m
Height: 2.1 m
Wingspan: 10 m
Wing area: 14 m²
Empty weight: 526 kg (1,160 lbs)*
Max. take-off weight: 850 kg (1.874 lbs)*
* Note: the biggest disparity in performance numbers I’ve found is in the weights. Most sources dealing with the B model put them at 526/850 kg, while two sources – which mostly covered the prototypes – put them at 460/760 kg. I haven’t found these numbers anywhere else, but it is entirely possible that the prototypes – given their record-breaking nature – were lightened by removal of equipment that was standard on the production versions.
** Similarly, the same two sources put the ceiling at 5,500 m (18,000 ft) as opposed to the B model’s 4,500 m (but this could be due to the engine, even though a 3000 ft increase is nothing to sneeze at)
With a growing fascination for the Technical Museum and the few – but fine – aviation exhibits within, today I was back there yet again, camera ready to cover anything I had missed in my previous report :). A definite case of I-need-a-life-ism, but my research for the first post on the topic had revealed that the Museum had definitely traded quantity for quality (or rather rarity), so I was naturally keen to see what else was I missing out on…
Suck, Squeeze, Bang, Blow:
Having said in the original post that I had only photographed the engines I thought interesting – and given my post-visit realization that EVERYTHING in the Museum is interesting 😀 – I decided to go back there and properly finish the job. And I’m glad I did, because quite a few gems had managed to sneak by me that first time…
Apparently destined to make up all the time since my last childhood visits to the Technical Museum, yesterday I made my third trip there in the space of a month :). A friend had asked me to take her to see the exhibition, an opportunity I used to upgrade the visit to an unofficial aviation history tour :D. Along the way, stopping at the engine section, we had noticed something on one of the engines that had eluded me before…
You may have seen an odd trident-configuration Daimler-Benz piston engine of unknown type down near the end of the report. I had it labeled as a six cylinder, information I then used in my unsuccessful attempts to find out more about it on the net. In a brilliant demonstration of my skills of perception, I had only noticed yesterday that the engine was in fact – a 12 cylinder…
Armed with this new found knowledge, I once again roved the Internet and think I may have nailed it this time… apparently, this is not a Damiler-Benz, but a Benz Bz.DV, the first German 12-cyl aero engine :). Designed in 1914, it weighed 425 kg and produced 250 HP, but I could not find a list of aircraft that had used it…
With quite a strong feeling of shame, I must admit that the last time I had visited the Technical Museum here in Zagreb – all 30 minutes away by tram – was back in primary school, some 15 years ago. Though I had been there a few weeks ago for the opening of the Croatian military aviation photo exhibition (featured a couple of posts back), being parking-meter-limited I couldn’t really take a good, thorough look around…
I had however noticed several aircraft hanging about, so feeling a little aviation-photography deprived – and with the weather steadily changing from awful to worse – I promptly set course for the museum for this year’s first photo report… 🙂
Along with the various flying machines, I had also stumbled upon an excellent collection of aircraft engines in an adjacent room :). I seem to remember seeing only one when I was here last time, so apparently the museum staff had been busy! 🙂 Though these are not all the engines on display, I had photographed the ones I had thought the most interesting…
Despite the fact having slipped by me for 11 and half months now, 2009. is a very important year for Croatian aviation – not only is the Croatian Air Force 18 years old this month (does that mean that it’s aircraft can now fly alone? :D), but this year also marks almost 100 years of aviation in Croatia, all the way from its modest start in 1910. and the first airplane built by Slavoljub Penkala, a noted Croatian inventor of Polish-Dutch origin (and coincidentally also the inventor of the mechanical pencil and fountain pen). To commemorate both of these occasions, the Croatian Military Museum had decided to put together a large photo exhibition, displaying publicly for the first time almost all available Croatian military aviation photos, from the first biplanes to the latest jets. [brag] I myself was also honored by having one photo on display, a first for me and proof that hauling all my photo gear around airshows the past few years does indeed pay off! [/brag] 🙂
The exhibition, opened on 15 December, was naturally split into several periods, of which the Interwar period (1918. to 1941.) and WW2 caught my attention the most. Two of the largest and most impressive sections – with almost 150 photos in total – they represented a very colorful part of aviation in Croatia, showing the smorgasbord of aircraft of all shapes and sizes that had been operated by the Air Force of the Kingdom of Yugoslavia and its “successor” forces, the Facist Ustaška Eskadrila and the socialist Partisan Air Force (and its Allied supporter, the Royal Air Force’s Balkan Air Force).
Naturally, these periods being the highlight of Borongaj’s history, I immediately combed through the collection, searching for aircraft that had been out of that airfield. The end list – by no means complete, there were a lot of photos to go through! – is impressive and encompasses over a dozen types from all corners of Europe.
1. From Czech Mate to the French Connection:
Given the shifting political and economic situation between the two World Wars, these aircraft ended up coming from all over Europe, from the UK to former Czechoslovakia (interestingly, the only major country with a significant aeronautical industry missing is Poland – though the Royal Yugoslav Air Force and its successors did operate Polish designs from other bases). It should be noted also that these only represent a fraction of the types operated by the various air forces of Yugoslavia and that the whole list would be significantly longer…
AVIA FL.3 – a small Italian side-by-side two-seater. Used by the Ustaška Eskadrila primarily for pilot training (later in the war some were also based at Lučko I believe)
Avia BH.33E – a biplane fighter with – interestingly – a shorter span upper wing than the lower (usually it’s the other way around, in which case the aircraft is a “sesquiplane”). Produced in a different Avia, this one from former Czechoslovakia
Breguet 19 – a biplane (and a real sesquiplane this time) light bomber and reconnaissance aircraft produced by Breguet of France
Dornier Do-17 (K and Z models) – the famous German high-speed light bomber from the early WW2 years
Dornier Do-Y – a very, very rare three-engined bomber designed by Claude Dornier (his second) back in the 30s. Few in number, I’m not sure if they had survived till the war…
Fiat G-50bis – a late 30’s Italian monoplane fighter, operated by both the RYAF (which had bought them pre-war) and the Ustaška Eskadrila (which had also received some new examples). Reportedly, only one survives to this day, kept in the basement of the Aeronautical Museum at Belgrade Airport, Serbia
Fieseler Fi-156C-1 Storch – the legendary German get-in-anywhere-anytime utility aircraft 🙂
Fiesler Fi-167A-0 – most probably the biggest oddity and rarity on this list, this carrier-borne torpedo bomber was transferred Croatia once it became apparent that Germany’s projected carrier, the Graf Zeppelin (for which the Fi-167 was designed) was going nowhere. Never seeing serial production, the models used by the Ustaška Eskadrila were all A-0 pre-production versions
Focke-Wulf FW.44B – a very well known German biplane training aircraft, much used before and during WW2. Unlike all other models which were powered by a Siemens radial, the B model unusually sported an Argus As 8 four-cyl inverted-V engine of 120 HP. Unfortunately, while the FW.44 as a type was quite common, the B models were rare, so pictures are hard to find…
Fokker F.IX (Avia F.39) – of similar class as the Do-Y, the Fokker F.IX started life in the 20s as a three-engined airliner. Though failing to gain a significant market as such, it did get some lease of life as a bomber, produced under license in Czechoslovakia as the Avia F.39. Like the Do-Y, they were operated by the RYAF and probably withdrawn from service before WW2
Hawker Fury Mk.IA and Mk.II – this very clean and fast British biplane fighter, a conceptual descendant of Hawker’s Hart bomber (an aircraft that in its day could outrun all existing fighters), was manufactured under license in Yugoslavia, hence it’s widespread use in the RYAF
Hawker Hurricane Mk.I – does this even need an introduction or a photo? 🙂
Ikarus IK-2 – another rarity on the list is a home-grown monoplane fighter, the not-at-all bad looking IK-2. Resembling a number of Polish high-wing monoplane and parasol fighters, this 1934 aircraft was used by both the RYAF and the Ustaška Eskadrila, and though a good dogfighter, it was no match for modern Axis and Allied fighters and was retired in 1944.
Messerschmitt Bf.109G-6 – like the Hurricane, this one’s pretty straightforward 🙂
Potez 25‘Jupiter’ – though this one isn’t. Used among other thing to start the first mail service from Borongaj to Belgrade, this French biplane/sesquiplane fighter-bomber saw widespread use in various air forces, including those of the Soviet Union, USA and Poland. The ‘Jupiter’, Yugoslavia’s license-built version, was powered by the Gnome-Rhone 9ac Jupiter radial
Rogožarski R-100 – another indigenous design, the R-100 was an intermediate trainer, the last step before the prospective student pilot was bolted into something armed and fast. Used initially by the RYAF, later in the war they were armed by the Ustaška Eskadrila with 80 and 100 kg bombs and used as ad-hoc divebombers
SIM X – something unknown that has the same name as Microsoft’s Flight Sim X, significantly complicating my search effort 😀