German aircraft industry in the interwar period: the “passenger bomber” Junkers Ju-86
First World War war ended with the signing of the Treaty of Versailles, which secured the victory of the Entente countries. Its terms were extremely disadvantageous and even humiliating for Germany, since the victorious countries achieved international demands for the disarmament of Germany: the sinking of the Navy, the ban on aviation and reduction in the number of personnel armies up to 100 thousand people. The officer corps was sharply reduced. It was forbidden to produce technologically complex military products: Tanks, armored cars, airplanes.
However, despite the fact that Germany was prohibited from having military aviation and building combat aircraft, the Reichswehr command constantly sought to circumvent these restrictions. For example, the concept of a “auxiliary bomber”—a civilian aircraft that, if necessary, could be quickly equipped with bombs and small arms—was popular there for a long time. Later, the exact opposite idea arose - to design a bomber that could be passed off as a passenger plane.
In 1932, at the German War Ministry, Lieutenant Colonel Wimmer prepared technical specifications for a twin-engine dual-purpose aircraft that could be used as a bomber and as a high-speed passenger or postal vehicle. Priority was given to military functions. The companies Junkers and Henkel began work on similar projects.
To circumvent the restrictions of the Treaty of Versailles, German aircraft companies created branches abroad, where they could freely build military aircraft. Thus, Dornier had enterprises in Italy and Switzerland, and Junkers had enterprises in Sweden and Russia. The three-engine Junkers G 24 (YUG-1) bombers, for example, were assembled in Sweden and armed in Soviet Russia. Everything was done in order to free one’s hands, gain experience and train the necessary personnel.
Development of aviation in Germany during the interwar period
The Treaty of Versailles of 1919, which was finally signed by Germany on June 28, contained provisions that provided for a sharp reduction in the number of both ground forces and naval forces. fleet, as well as the complete abolition of the German air force. During the war, at least 15 aircraft and 000 aircraft engines were included in materiel transferred to the Allies, and by 27 military aviation in Germany was dead.
Although the Treaty of Versailles prohibited Germany from using military aircraft, it limited engine power to civil aviation only. Already in December 1917, the first German airline operating scheduled flights, Deutsche Luft-Reederei (or DLR), was created, although flights were not carried out until February 1919. Soon after this company was used by several other smaller companies, all using converted military aircraft such as the AEG J. II, LVG C. and Friedrichshafen G. IIIa.
The first civil aircraft produced in Germany was the Junkers-F 13, a highly advanced low-wing monoplane of all-metal construction that could accommodate two crew and four passengers. Although the F13 was significantly ahead of most modern aircraft of the time, it was initially considered a used military aircraft, and it was not until late 1919 that the first six were sold in the United States.
This deal was soon thwarted by the efforts of the Inter-Allied Aviation Control Commission, which confiscated all aircraft under construction, explaining that the F-13 was equally suitable for military operations. Although this decision was in some ways justified, the commission eventually relented in February 1920.
To help promote the F 13, Junkers founded its own airline in 1921, known as Junkers-Luftverkehr. Eventually, on 6 January 1926, Junkers Luftverkehr and Deutscher Aero Lloyd (successor to DLR) merged to form Deutsche LuftHansa, in which the government owned more than 37% of its shares. The director of the new company was Erhard Milch, a shrewd businessman who quickly turned the airline into one of the largest and most efficient in the world.
Although Germany's armed forces were sharply reduced, a small Ministry of Defense (Reichswehr-Ministerium) remained in Berlin. The head of the army command was General Hans von Seeckt, a far-sighted officer who, back in 1921, began to form a small aviation department within the ministry. In December 1923, the ministry signed an agreement with the Soviet government to provide educational facilities in Lipetsk. The training of the first recruits began in 1924, and within nine years the school was to provide Germany with several hundred pilots and mechanics.
In parallel with the training in Lipetsk, the German airline Luftsportverband (DLV) provided potential pilots with initial training in flying gliders, balloons, and later airplanes. The organizer of these courses was Karl Student, who would later head the Luftwaffe Parachute Corps. By 1929, the DLV had over 50 members.
History of the Junkers Ju 86
The first all-metal Junkers aircraft was the J 1, which was built in 1915 under the direction of Professor Hugo Junkers. This aircraft was developed from the Junkers DI monoplane fighter into the F 13 four-seat transport aircraft, which played a vital role in the development of world aviation.
The Junkers-F 13 prototype, which flew on June 25, 1919, as mentioned above, was one of the most advanced aircraft of its time. The basic design of the Junkers-F 13 was continuously improved between the two world wars, resulting in the G 23/24, G 31, W 33, W 34 and, in 1930, the Junkers Ju 52.
In 1926, Junkers released improved versions of its single-engine, four-seat transport aircraft, the F 13, which had a significant impact on German aviation and air transport in many parts of the world. The new aircraft, the W 33 and W 34, were primarily intended for cargo transport, but their aviation versions included seating for six passengers.
These aircraft were cantilever monoplanes with the familiar Junkers corrugated metal skin. The only difference between the two aircraft was that the W 33 was powered by a liquid-cooled inline engine, while the W34 was powered by an air-cooled radial engine.
As for the Junkers Ju 86, it is one of those little-known aircraft that appeared in the mid-1930s and was supplied to the Luftwaffe during the period of their secret creation. However, when the war began, it was considered obsolete and was practically not used in combat.
Although this aircraft was not actually very successful, it is of interest as an early example of a diesel-powered aircraft.
In 1934, Junkers and Heinkel were given technical specifications for the development of a modern twin-engine aircraft capable of being used both as a high-speed airliner and as a medium bomber for the nascent Luftwaffe. Each company ordered 5 prototypes.
Developed under the leadership of diplomat Ernst Zindel, the Ju 86 was a contemporary of the more successful Heinkel He 111. Like the Heinkel He 111, it combined the qualities of both a medium bomber and a passenger aircraft intended for commercial transport. To formulate and, as far as possible, integrate these functions, RLM and Deutsche Lufthansa worked together.
Various civilian and military versions of the Ju 86 were to be built. However, the requirements were not entirely compatible and the focus was on developing a fast medium bomber version at the expense, if necessary, of a passenger airliner (which was needed more for prestige than economic purposes).
The basic design was a twin-engine monoplane with low wings and twin stabilizers and rudders. The metal construction with reinforced plating was unusual for Junkers, as the plating was smooth and free of rough edges.
The tapered wing had two main spars and one auxiliary spar, as well as conventional flaps and ailerons of the Junkers auxiliary wing type. An unusual feature for an aircraft of this size was that the main landing gear was attached at the base of the wing and retracted outward to form a very narrow track.
Having ordered three military and two civilian prototypes, Junkers in Dessau began building the first prototype, the Ju 86a or V1 (tail number 4901), which first flew on 4 November 1934. Since two Junkers Jumo 205 diesel engines with a power of 600 hp each. s., for which the aircraft was designed, were not ready, it was equipped with two radial air-cooled Siemens SAM 22 engines. Flight tests of this aircraft were disappointing, since its stability and controllability were unsatisfactory.
The military and civilian versions of the aircraft differed in the forward part of the fuselage (with and without a navigator-bombardier's cabin), the presence or absence of weapons and cabin equipment. The passenger car had a cabin with ten seats in the fuselage, while the military car had internal bomb cassettes located there. The fuselage was too small to accommodate passengers, which made the passage narrow; people could only move by bending their heads. For a bomber, the space in the middle part of the aircraft, on the contrary, was too much. Only a small part of it was occupied by internal cluster bomb racks.
In January 1935, the Ju 86 V3, Dalal (tail number 4903) became the second prototype to fly and, although initially powered by Siemens 22 engines, was replaced in March by the first available Jumo 205C diesels driving three-bladed propellers. The V3 was similar to the V1, but had a glazed lower nose to accommodate a bomb carrier and a hand turret mounted on the top of the nose. Diesel engines had narrow nacelles, but under each of them there was a large radiator.
The use of the Jumo-powered Ju 86 bomber during the Spanish Civil War demonstrated that it was inferior to its competitor the He 111, as diesel engines proved unsuitable for the harsh conditions of combat. For this reason, production plans were reduced, and two aircraft were even sold to the Francoists. Production switched to the Ju 86E version, powered by a BMW 132 engine, and continued until 1938.
At the outbreak of World War II, only one group of Ju 86 bombers (III KG 1 Hindenburg) remained in service and were used during the invasion of Poland in 1939. However, it was soon replaced.
Использованная литература:
[1]. Smith, JR; Kay, Antony L. German Aircraft of the Second World War. London, 1972.
[2]. Kotelnikov V. R. Medium bomber "Heinkel" He. 111. "Worker bee" of the Luftwaffe. – Moscow: Yauza-press, 2022.
[3]. Dressel, Joachim; Griehl, Manfred. Bombers of the Luftwaffe. London, 1994.
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