PTT, Dave Unwin
What's the best design for the job? Latest is not always best
There is often a temptation for aficionados of Western aeronautics to sneer in a superior and condescending fashion at the various aircraft produced by the design bureaux of Antonov, MIG, Tupolev and Yak. While writing up my report on the SZD-45 Ogar (see p.24), it occurred to me how a country’s cultural, philosophical and even political ideologies can be reflected in an aircraft’s design.
I remember chatting to a US Navy pilot who opined that “if it’s ugly it’s British, if it’s weird it’s French, and if it’s ugly and weird it’s Russian”. He also steadfastly maintained that the Soviets “copied everything”. Blinkered by bigotry, this individual didn’t possess the intellectual capacity to understand that, with any welldesigned machine, form must follow function. Similar to the Ogar, another aircraft that I’ve flown which is a product of the Cold War and well illustrates the clarity of thinking often displayed by the Soviet design bureaux, is the Antonov AN-2. Indeed, the AN-2 is a particularly good example of pragmatic design.
In 1947, when Western aeronautical engineers were gleefully contemplating the myriad applications they could find for the new jet and turboprop engines which were becoming available, they must have been both amused and bemused by Antonov’s latest but anachronistic design, which was a big biplane powered by an air-cooled radial engine! Yet, for the kind of missions for which the aircraft was intended, it remains an eminently practical solution and probably explains why so many were built over such a long period of time.
Firstly, why a biplane? Well, the original requirement issued by the USSR’S Ministry of Agriculture and Forestry specified a machine that, while not overly fast, could operate from small, unprepared strips on short sectors. It is a simple fact that good STOL performance is inextricably linked to a low wing loading, which in turn requires a large wing area. That means either two very big wings, or four, stacked two on top of each other and separated by I-type interplane struts−i.e. a biplane! To increase its Stol-ability still further, it has leading-edge slats on the upper wings and flaps on all four wings. The ailerons on the upper wing also droop when the flaps are extended.
Antonov knew that as state airline Aeroflot operated in four of the world’s five major climatic zones, its aircraft had to be capable of functioning in widely disparate conditions, ranging from the savage sub-zero temperatures of a Siberian winter to the searing summer heat of the Gobi Desert. This is one of the reasons the Soviet designers tended to prefer air-cooled engines, and pneumatic systems over hydraulic. One clever feature is that the two large batteries slide in and out on racks that feature built-in connectors. Extreme cold can suck the life out of even the best battery very quickly, so this arrangement allowed crews easily to take the batteries out and store them somewhere warm overnight.
Another excellent facet is that the on-board enginedriven compressor, which recharges the eight-litre air tank, can also be used to inflate the tyres and oleopneumatic shock absorbers. And how would you know if the oleos were a bit deflated? Simply open a small door on the main leg fairing and see if the mark for the aircraft’s current weight is aligned with the index mark on the strut.
Perhaps my favourite feature though is that the fuel system has a built-in pump for uplifting fuel. When refuelling from a 200-litre drum in the middle of the steppes, open a hatch in the belly, connect the hose and away you go! To say that the AN-2 is an incredibly versatile machine would be a huge understatement. A considerable number of variants were built, including dedicated crop-sprayer, ambulance, floatplane, waterbomber and paratrooper versions. AN-2S were exported to all the old Warsaw pact states, as well as many other countries.
Antonov produced at least 5,000, while PZL’S Mielec factory in Poland and China’s Nanchang Aircraft Manufacturing Company built many more under licence. The grand total manufactured is possibly as many as 20,000, with production only ceasing in 1995. Not bad for a machine that most Western observers considered obsolete before it even entered production! Just like that other icon of Soviet engineering, the Kalashnikov assault rifle (which also made its debut in 1947, whence its name, Avtomat Kalashnikova 47) the AN-2 isn’t the most sophisticated machine, but it gets the job done.
As for the allegation of copying... well, it is true that Russia’s Arkadia Shvetsov bureau developed the ninecylinder air-cooled Ash-62 from the Wright Cyclone R-1820, but as the Cyclone was one of the most reliable aero-engines in the world at this time, this approach seems eminently logical. Similarly, there is nothing revolutionary about the AK-47, it is simply a combination of the best features of the Garand M-1 used by the American army and the German STG44 for, as Mikhail Kalashnikov himself observed, “each designer seems to have his own paths, his own successes and failures. But one thing is clear: before attempting to create something new, it is vital to have a good appreciation of everything that already exists in this field”.
This really is excellent advice−and advice that some modern aircraft designers would do well to heed!
The AN-2 is a good example of pragmatic design
Pilot’s Flight Test Editor operates a Jodel D.9 from a farm strip and has logged stick-time on everything from ultralights to fast jets