Above the lakes, above the vales: The Koser / Koser-Hrovat KB-3 Jadran hydroglider

A Koser / Koser-Hrovat KB-3 Jadran hydroglider, Adriatic Sea, summer 1949. Behind it, a passenger ship of the government-owned shipping firm Jadranska Linijska Providba. Anon., “Gliding and sailplanes in Yugoslavia.” Sailplane and Glider, June 1950, 125.

Zdravo, my reading friend, hello!

Would you be interested in some philosophical musings on this fine day? What, exactly, is an aircraft, for example? A quick peek at a few online dictionaries and databases reveal that an aircraft is a vehicle which travels through the air. An airplane is a type of aircraft, and so is a helicopter. And so, more surprisingly, a least to me, is an airship or balloon.

A glider is an aircraft, of course, but is it an airplane? Given that, according to the same online dictionaries and databases, an airplane is a flying vehicle, a heavier than air vehicle in at least one case, with wings and one or more engines, a glider is not an airplane. How bizarre, if yours truly may quote a line from the eponymous hit song released in December 1995 by the New Zealand music group OMC, an acronym which stood for Otara Millionaires Club – a somewhat ironic / sardonic moniker given that Otara was / is the one of the poorest suburbs in the greater Auckland area.

And yes, the topic of this week’s curatorial pontificatory exercise will be a glider and… Yes, your question is indeed very much in keeping with our philosophical slant. Is our aircraft of the week a glider or a sailplane? Well, given that the latter is an unpowered aircraft which can remain airborne by having its pilot take advantage of rising air currents, we can conclude that our aircraft of the week is a sailplane.

One could argue that our story began in 1947 with the design of a modern sailplane, the Koser-Hrovat KB-1 Triglav, or, as it was initially called, the Karavan, by Koser Jaroslav and Hrovat Stojan, a couple of students at the Tehniška fakulteta v Ljubljani of the Univerza v Ljubljani, in other words the Ljubljana technical faculty of the university of Ljubljana, in Ljubljana, Yugoslavia (now in Slovenia).

From the looks of it, a sport aviation committee in Slovenia, one of the socialist republics of Yugoslavia, launched a competition in 1947 for the design and production of a so-called Olympic type sailplane, whose goal was presumably to replace the DFS Olympia Meise, a German design test flown in 1938 and produced in various numbers in many countries (Australia, Austria, Brazil, Czechoslovakia, France, Germany, Hungary, Netherlands, Sweden, Switzerland and United Kingdom) before, during and after the Second World War. The Olympia Meise, which was to be built in various countries, was to be used in the competitions held at the Games of the XII Olympiad, to be held in Helsinki, Finland, in the summer of 1940. Said games were of course cancelled as a result of the Second World War.

One has to wonder if the ultimate goal of the sport aviation committee’s endeavour was to create a new glider for the Organisation scientifique et technique du vol à voile, an organisation associated with the Commission de vol sans moteur of the Fédération aéronautique internationale (FAI). Do I really need to type the whole spiel about the FAI? Sigh. You’re mean. The FAI, say I, gripe gripe, was the Paris-based world governing body for all manners of aeronautical records mentioned many times in our blog / bulletin / thingee since January 2018, but back to our story.

It is possible, I repeat, possible, if rather unlikely, that the FAI and / or the Switzerland-based Comité international olympique briefly considered the possibility of bringing back gliding as a demonstration sport or full Olympic sport, possibly in time for the Games of the XV Olympiad, to be held in Helsinki, in the summer of 1952.

A brief digression if I may. Yours truly was quite surprised to hear (read?) that Yugoslavia was a (European? world??) leader in glider / sailplane design in the late 1940s and early 1950s. Various government organisations encouraged a great many young Yugoslavs, both female and male, to enlist in the country’s 35 or so gliding schools to become glider / sailplane pilots.

As things turned out, gliding was not brought back as a demonstration sport or full Olympic sport, and the Triglav, as popular as it as with pilots, was not produced in large numbers (12 or so?). Incidentally, this sailplane flew for the first time in the fall / autumn of 1948. From the looks of it, the Triglavs were built by a small government owned firm whose named included the word Letov – and that’s pretty much all yours truly can say about it.

Even so, Koser (and Hrovat?) used the Triglav as the starting point of their next design, a hydroglider / amphibious glider, the KB-3 Jadran. Intended for flying along the shores of the Adriatic Sea (Jadransko More in Croatian, Serbian and Slovenian – 3 of the languages spoken in Yugoslavia), this elegant machine was allegedly / conveniently completed, at the Letov factory, on 25 May 1949. This date was significant in that it was the birthday of the Yugoslav president / dictator Josip Broz Tito, who was in fact born on 7 May, and… Why the puzzled look, my reading friend?

Ahh, I see. Well, it so happened that, on 25 May 1944, the German military launched a serious assault on the supreme headquarters of the national liberation army of Yugoslavia, a Communist-led organisation headed by Tito, who was rather lucky not to be captured or killed. Tito more or less officially changed his birth day to 25 May around 1945-46, to commemorate this battle, which, in the end, had not gone too well for the Germans – something we can all cheer about.

Before you raise your hand to ask a question about hydrogliders, let me point out that examples of more than 50 different types of hydrogliders have been built, in single units or in small numbers, in at least 14 countries (Australia, France, Germany, Greece, Hungary, Italy, Japan, Poland, Portugal, Sweden, Union of Soviet Socialist Republics, United States, United Kingdom and Yugoslavia) since the end of the First World War.

While yours truly intends not to divulge anything about the Jadran at this moment, I will point out that few if any of these hydrogliders left much of a mark on the world.

Still, in 1940, a small German outfit, Flug- und Arbeitsgruppe Göppingen, made a single example of a hydroglider, the Gö 8, as part of a project launched by Dornier-Werke Gesellschaft mit beschränkter Haftung. At the time, this well-known aircraft manufacturing firm was developing a ginormous transatlantic flying boat airliner, the Do 214, for National Socialist Germany’s national airline, Deutsche Lufthansa Aktiengesellschaft. The Gö 8 was a 1:5 scale model, with a crew of 2 and a wingspan of 12 metres (39.4 feet), of the Do 214. It was used for towed tests in the open air, to see if the hull of the future airliner was as hydrodynamic as possible. No example of the Do 214 was ever built, by the way, because of the Second World War.

If yours truly may be permitted a comment, putting in service a 145 000 kilogramme (320 000 pound) aircraft to carry no more than 40 passengers, on 2 decks, with 2 dining rooms, was the height of lunacy. And yes, using ginormous rigid airships to carry a similar number of passengers across the Atlantic was also the height of lunacy.

Richard Mihm’s RM-4 was another hydroglider that I found interesting. Completed in 1937, this German machine remained aloft almost 14 hours in November of that year, thus granting to its crew a new world endurance record for 2-seat sailplanes.

Finally, I would be remiss if I did not mention an American unpiloted hydroglider which predated the end of the First World War by more than 20 years, namely the large biplane kite on floats completed around 1897 by Edson Fessenden Gallaudet, around the time he worked as a physics instructor at Yale University. Would you believe that this kite was seemingly fitted with some sort of wing warping control system – the very type of system which allowed Orville and Wilbur Wright to make the first controlled and sustained flight of a powered aeroplane, in December 1903?

Gallaudet did not patent his idea but the Wrights certainly did. From 1909 onward, they also sued numerous individuals, both Americans and foreigners, who were trying to make a buck through aviation in the United States. This unfortunate episode known as the patent war put the brakes on the development of aviation in the United States before the First World War. And yes, my reading friend, the Wright brothers were mentioned many times in our you know what since August 2018.

And no, the Wrights did not copy Gallaudet’s idea. They came up with the idea of wing warping on their own.

So, would you like to see yours truly divulge some information on the Jadran? Good answer. This elegant flying machine proved to have good flying characteristics. Although designed to land on water, on a river, lake or sea, it could also land on land. This being said (typed?), the first “landings” of the Jadran were made on a river and a lake. Trials over the Adriatic Sea followed soon after. The towing floatplane, a version of a Yugoslav aircraft known as the Ikarus Aero-2, was similar in appearance, power and concept to the Fairchild Cornell, an aircraft found in the world famous collection of the Canada Aviation and Space Museum, in Ottawa, Ontario. Mind you, it was also possible to launch a Jadran using a winch mounted on a floating platform.

Sadly enough, not too many people in Yugoslavia and elsewhere showed an interest in acquiring and / or building a Jadran. As a result, only a few examples (4?) of this very interesting machine were built. They were scrapped at some point during the years of the Cold War.

On this cheerful note, I bid you farewell. For now.

And yes, the first words of the title of this article are the first words of an English version of the poem Élévation, included in Les Fleurs du Mal, in English The Flowers of Evil, a magnificent book of poetry published in French in 1857 by a giant of French literature, Charles Pierre Baudelaire. A version of this poem recorded as a song in 2005 by the French blackgaze and post-metal band Alcest, was / is well worth listening to. Seriously.

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Rénald Fortier