The Junkers were the Prussian German-speaking aristocracy who controlled vast estates in what is now Eastern Europe. The story of that unhappy chapter of European history and how it got that way, is best to left to other writers on Medium.
In this case, we are talking about a long line of innovative aircraft produced by an engineer named Hugo Junkers, whose original aircraft the J 1 was the world’s first flyable all-metal aircraft, and one of the fastest machines of its day in 1915. The firm went on to produce a limited number of other types during the Great War. Just after the war, a four-passenger monoplane designated the F-13 was produced, which has the distinction of being the world’s first all-metal airliner. The outer skin used duralumin, a copper-manganese-aluminum alloy. By using a corrugated structure the metal was strengthened further, reducing the need for rivets and making it easy to work with. It was to become a trademark of all Junkers passenger aircraft.
Production restrictions imposed on Germany after the Armistice that ended the war forced Junkers to manufacture aircraft in the Soviet Union commencing in 1922. There they produced the single-engine G.24 and later the three-engine G.31. The G.31 became famous as practically the only means of transport in New Guinea (once a German colony) that had mountainous terrain and very few motorable roads. A fleet of three Junkers G.31s linked the goldfields in the interior with ports on the coast. Vehicles, livestock, mining equipment, and personnel were flown into the goldfields, and processed gold flown out. It is estimated that, at the time, the three G.31s hauled more freight in a year than the rest of the world’s aircraft combined.
The need for three engines
A bewildering number of restrictions, designed to prevent Germany from re-arming after the First World War, meant that in addition to not being able to have factories in Germany, engine power was also severely limited. So Junkers designed both single- and three-engine variants of the same basic type. Accordingly, even the low-powered engines of the time were capable of carrying a reasonable payload.
An added benefit was that in the case of an engine failure (not uncommon in those days) a three-engine machine could continue to fly safely, and even climb should the failure occur on takeoff. This feature allowed the newly formed German airline Deutsche Luft Hansa to make history by scheduling a passenger flight at night, on the Berlin-Königsberg route using the Junkers G.24 aircraft.
Königsberg was separated from the rest of Germany by Poland, with no land access to the rest of the country. The redrawing of boundaries in Prussia after the Armistice ensured that cities like Königsberg and Danzig had ethnic German populations, but were surrounded by countryside that counted as hostile territory. Today, Danzig has been renamed Gdansk and is wholly in Poland. Königsberg is known as Kaliningrad, and is Russian territory, though it has no land border with Russia. Both cities are devoid of German residents, a consequence of the ethnic cleansing that took place after World War 2 — an oft-ignored part of European history.
The G.24 was a popular aircraft, with at least 72 manufactured, of which Luft Hansa operated 26. The airline used this capable machine on many of its routes; including a pioneering service between Berlin and Peking (now Beijing) over 20,000 kilometers away, a journey that required ten stops at the time.
Development of the Ju 52
Junkers also built the W 33 model, a single-engine transport that set many records, including the first east-to-west trans-Atlantic crossing (against prevailing winds) in 1928. Over 199 of these aircraft, powered by a single six-cylinder liquid-cooled engine produced in-house by Junkers, were built between 1927 and 1934.
Initial plans for a larger replacement aircraft had many innovative design features. A single-engine version dubbed the Ju 52/1m, powered by a V-12 liquid-cooled engine, was sold to Canadian Airways in 1931. The aircraft nicknamed the ‘Flying Boxcar’ performed brilliantly. Its duralumin construction and cavernous rectangular cabin meant it was perfectly suited for the harsh environment. Operating on wheels, floats and skis, depending on the season, the Ju 52/1m could carry passengers and cargo deep into the northern provinces of Canada.
The engineers eventually decided to revert to the three-engine concept, designating the aircraft the Ju 52/3m. Radial nine-cylinder BMW 132A engines were finally selected, as they did not require complicated plumbing (for coolant) and were easy to service. The use of NACA cowlings on the wing engines reduced drag; a slimmer Townsend ring did the same for the nose-engine. Weight savings from the air-cooling and resulting ease of maintenance more than offset the increased drag of the radial engines. However, the drag caused by the corrugated duralumin skin and the fixed-landing gear was considerable, causing the aircraft to be slower than many of its contemporaries
The wing engines were also mounted perpendicular to the swept-back wings, for better controllability in the event of an engine failure. This gave the Ju 52 a distinct silhouette when viewed from below, as the engines appeared to be splayed outwards. The fuselage was of a rectangular cross-section, which had become a trademark of the Junkers stable. The wing also had a narrow section running the entire width of the trailing edge, which functioned as a combination flap and aileron. This gave the Ju 52 a very low approach speed and made it look like it had a double wing when coming into land.
Germany’s flag-carrier Luft Hansa became the largest user of the type, the three engines allowing the airline to launch a direct service between Berlin and Rome, flying over the Alps. This flight took eight hours to cover the 1,200 km (700 mile) distance, providing passengers with spectacular views from the large windows, but also giving some idea of how slowly the Junkers flew.
Luft Hansa eventually flew 231 examples of the Ju 52/3m. Airlines in Finland, Sweden and Brazil were also early users of the type. Eurasia Airlines, a joint venture between Germany and China, would also be a major operator of the aircraft, with a large fleet that linked many cities in China, in addition to services to regional business hubs such as Hong Kong and Hanoi. Tante Ju (or ‘Aunty Ju’, as the Ju 52 was affectionately known in Germany) proved to be a reliable and versatile machine in many different parts of the world.
Meanwhile in Europe, Hitler’s Nazi party came to power and the drums of war were beating once more. Hugo Junkers was firmly opposed to their ideology, and the Nazis retaliated by seizing control of his company in 1935.
Tante Ju goes to war
The focus immediately became to transform the Ju 52 for military use. Junkers, among other German manufacturers, secretly developed dedicated bomber aircraft. The Ju 87 ‘Stuka’ dive-bomber was already operational, and Junkers’ designers worked on a faster bomber which was to become the Ju 88. Meanwhile Tante Ju was also adapted for that purpose, with a version capable of carrying up to 1,500 kg (3,300 lbs) of bombs, and armed with two machine guns as defensive armament, soon produced.
The first use of the Junkers in combat came in the Spanish Civil War, which was waged from 1936 to 1939. In its early days, a fleet of Ju 52s operated by the Condor Legion (German-crewed aircraft on the side of the Nationalist forces) ferried troops of the Spanish Foreign Legion from Morocco to Spain, providing crucial manpower that helped save General Francisco Franco’s forces, whom the Nazis were supporting. Condor Legion pilots also flew the Stuka, using it as ‘airborne artillery’, and developing tactics later used in the Blitzkrieg.
During the Spanish Civil War war the Ju 52 was used extensively as a bomber, including during the assault on Madrid and the notorious raid on Guernica. On at least one occasion Ju 52 bombers raided parts of Madrid, while civil Luft Hansa Ju 52s operated scheduled services to the same city, in a juxtaposition rarely repeated since.
While the Junkers was used extensively as a bomber in Spain, it proved to be vulnerable to interception due to its slow speed. The type was approaching obsolescence, but its reliability and the large numbers in existence (almost 5,000 were built) meant that it remained the primary transport aircraft of the Luftwaffe until 1945.
Tante Ju was used extensively in every theater of war, from the Russian campaign (often on skis) to the burning deserts of North Africa, and in Norway, where the seaplane version saw duty. It is also famous for its role in the battle of Crete, the first entirely airborne invasion.
The Ju 52 was the mainstay of the Luftwaffe’s transport arm, proving to be the equivalent of the Douglas DC-3 Dakota/C-47 for German forces. Adolf Hitler used one as his personal transport, as did Chinese Nationalist leader Chiang Kai-shek. While other sleeker, faster, more lethal Luftwaffe aircraft have become better known, the Ju 52 lived up to its nickname — acting the part of a reliable, affectionate and trustworthy aunt, always there when needed.
The venerable transport continued in use after WW2, with the Swiss, Portuguese and Spanish air forces operating the type for several decades. Both France and Spain continued to manufacture the aircraft, as the Amiot AAC.1 Toucan and CASA 352 respectively, for many years after the war.
The Swiss Air Force finally retired the aircraft in 1982, when the indomitable Ju 52s were taken off active service but continued to be employed for sightseeing tours with Ju-Air until 2018. They have been grounded since, due to corrosion that resulted in a fatal crash that year.
It appears that only one Ju 52 (at the Military Aircraft Museum in Virginia Beach, Virginia, USA) is still airworthy. A restored CASA 352L is awaiting certification in Johannesburg, South Africa and another is reportedly stored in France, but its status is unknown.
This is part of a series on the historic propliners that gave birth to the airline industry and the slow transition to the jet age. The peerless HP-42, the Ford Tri-motor and then the DC-3 of course. My columns move through the other Douglas propliners, the Boeing 377, Lockheed’s Electras and the elegant Constellation. The Brabazon Committee which sparked such a wave of innovation in the UK with the Vickers Viscount, the Bristol Britannia and the ill-fated de Havilland Comet. Many other significant aircraft, such as Avro Canada’s innovative but aborted C-102 passenger jet and the Sud-Aviation Caravelle, which led us into the start of the Jet Age have columns too.
A few quirky segues I couldn’t resist: the ‘Double Sunrise’ flights between my two homelands Ceylon and Australia; the wonderful Carvairs and that very British habit of taking your car on holiday. I also had to write a paean to my beloved A380 and all my pilot friends in the Gulf as COVID ended that little dream.
Thanks for reading and I hope you enjoyed the series as much as I have relished writing them. My special thanks to my old friend, mentor, editor and repository of knowledge Roger Thiedeman, for all the encouragement and support throughout this project.