Junkers (Aircraft)

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Junkers & Co was a major German aircraft manufacturer. It produced some of the world's most innovative and well known airplanes over the course of its fifty-plus year history in Dessau, Germany. It was founded there in 1895 by Hugo Junkers, initially manufacturing boilers and radiators. After World War I the company switched to manufacturing airplanes. During World War II the company produced some of the most successful Luftwaffe planes, as well as piston and jet aircraft engines, albeit in the absence of its founder, who by then had been removed by the Nazis.

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[edit] World War I

The only surviving J.I at the Canada Aviation Museum.
The only surviving J.I at the Canada Aviation Museum.

The history of Junkers aircraft production begins with the Junkers J 1 mid-wing monoplane (not to be confused with the later, all-metal sesquiplane ground attack aircraft J.I which had a factory designation J4). Research for this aircraft began in 1914 and was interrupted by the start of the First World War. The prototype aircraft, named the Blechesel (Sheet Metal Donkey), was completed in 1915 after the outbreak of the war. This aircraft is significant in that it was the first flyable aircraft to utilize an all-metal "total strutcural" design. Contemporary aircraft were built around wooden frames constructed in a rib-and-stringer fashion, reinforced with wires, and covered with a stretched fabric. The J1 was a semi-monocoque design, using steel ribs and sheeting that formed both the stringers and the skin. At the time aluminium was still fairly expensive, so the J1 was made of sheet steel. It was quite heavy as a result, which translated into poor climb and maneuverability, yet its clean monoplane layout, which even featured a ventral "belly" radiator installation for its Mercedes D.II inline-six cylinder engine, had very low drag, and the J1 was one of the fastest planes of its day, reaching speeds of 170 km/h, with only a 120 hp engine for power.

Following the J-1, a series of "J-designated" aircraft followed, each advancing the state of the art in terms of strength and weight, but no single design progressed much beyond the prototype stage in terms of production potential. The J2 was an extensively "cleaned up" J1, while the J3, a single rotary engined mid-wing monoplane design, was to replace the steel sheeting with corrugated duralumin. IdFlieg, in charge of aircraft evaluation, was unconvinced of the monoplane layout of these designs, and ordered a biplane version as the J4. Junkers took this opportunity to produce the entire aircraft of corrugated duralumin (except for some fabric on the rear fuselage) in order to lower weight. The J4 became Junkers' first design to enter production, with orders totalling 283, of which about 184 were delivered to operational units. Since it was the first design from Junkers to serve in the Luftstreitkräfte's "J-class" of armored, infantry co-operation aircraft, which also had aircraft designed by Albatros and AEG serving with it in the same capacity, the curious and confusing instance of the Junkers J4 armored all-metal sesquiplane getting the German military designation "J.I" was one caused solely by the Luftstreitkräfte's choice of letter for all of their armored, ground forces co-operation aircraft class in World War I.

Junkers continued to believe in the monoplane layout, and continued the J-series with a number of newer monoplane designs. One of the most successful was the J7, which was later stretched to form the two-seat J8. The J8 was the first cantilever monoplane design, and looked extremely "modern" when compared to contemporary wire-braced biplane designs. The J8 was put into limited production by Fokker as the J10, a small number of which saw service on the Eastern Front just before the war ended.

The corrugated duralumin wing and fuselage "skin" introduced in the J-series became a trademark of Junkers aircraft built in the 1920s and 30s. Development continued during the course of World War I, including a growing (but troublesome) partnership with Fokker, as the "Junkers-Fokker Werke", abbreviated "Jfa" by the German government of the time. Several Junkers designs were licensed to Fokker during this period. The visual similarity of Junkers and Fokker aircraft during the next decade is attributable to this early affiliation. The Great War ended with German Navy trials of model J11 which was an all metal floatplane prototype.

[edit] Interbellum

In the immediate post-war era, Junkers used their J8 layout as the basis for the F-13, first flown on 25 June 1919 and certified airworthy in July of the same year. This four passenger monoplane was the world's first all-metal airliner. Of note, in addition to significant European sales, some twenty-five of these airplanes were delivered to North American customers under the Junkers-Larsen affiliate and were used primarily as airmail planes.

The Treaty of Versailles signed only days after the F-13 flew, initially forbade any aircraft construction in Germany for several months. After that span of time only the design of civilian aircraft was permitted to Germany. Junkers developed a series of progressively larger civil aircraft including the single engined G.24 and three engined G.31. Neither aircraft was a commercial success. With the expiration treaty restrictions in 1926, Junkers introduced the Junkers W33 and Junkers W34 series which did find significant commercial success via large production orders in passenger, freight hauling, and, somewhat later, military configurations. The W-33/W-34 series also set multiple aviation "firsts" including records for flight duration, flight distance, altitude, rocket assisted take-off and inflight refueling between 1926 and 1930.

Junkers' produced a design study in 1924 for a visit to the United States. The study outlined a four engined 80 passenger seaplane, incorporating a forward canard wing as well as a main wing, both of which were fitted above twin catamaran hulls. Passenger seating was to be provided both in the main wing and the hull sections of the craft. This Junkers design, including a scale model, was intended to illustrate an aircraft capable of trans-Atlantic operations of 8 to 10 hours and was completely revolutionary for its day.

The basic principles outlined in this design were later introduced in the Junkers G.38, which was introduced and put into regular service by Lufthansa. At the time of its introduction, this four engined transport was the largest landplane in the world carrying thirty-four passengers and seven crew members. The G.38 sat some of its passengers in the wing area outboard of the fuselage, the front of which was covered with windows.

[edit] Financial troubles

Around 1931 the company suffered from a series of financial difficulties that led to the collapse of the group of companies. The existing shareholders pressured Hugo to leave the company. Hugo, however, was the patent holder on a wide variety of the technologies used in most of the existing Junkers designs, including many of their engines.

A plan was started to solve both problems by "buying out" Hugo's engine patent portfolio and placing it into the hands of a new company, the Junkers Motoren-Patentstelle GmbH, which was eventually formed in November 1932.[1] The new company would then license the technologies back to the various companies, most notably what was then Junkers Motorenbau (one of many "Jumo" companies). However, before Junkers actually transferred his patents to the Patentstelle, the collapse of the Junkers consortium was solved by the sale of the Junkers Thermo Technik GmbH to Robert Bosch who still uses the brand name to the present.

[edit] Nazi takeover

The Nazi party came to power in Germany in 1933 and all German aviation development was shifted away from long-range civil aircraft types. Hugo Junkers himself was forced to transfer all his patents to the Nazis, who doubted that Junkers would comply with their plans. Shortly after, his holdings were expropriated and he was placed under house arrest. The company that had pioneered commercial aviation development for at least a decade was relegated to relatively small one- and two-engined military design competitions issued by the Reichsluftfahrtministerium (RLM) the "Reich Aviation Ministry". Two exceptions to this were the legendary Ju 52 and the Ju 90.

Ju 52 development had started in 1928 as a single-engined commercial transport and evolved, initially to a two-engined, later into the classic "trimotor" design for which the Tante Ju became world famous. The Ju 52 was a bona fide commercial success, with over 400 airplanes delivered to various airlines around the world prior to the outbreak of World War II, including the countries of: Finland, Sweden, Argentina, Brazil, Uruguay, Ecuador, Peru, Mexico, South Africa, Denmark, Norway, Italy, UK, Belgium, Hungary, Estonia, Greece, Spain, and of course, Germany. Amazingly, and in tribute to its rugged design, both Spain and France resumed Ju 52 production after cessation of the Second World War.

With the introduction of the Junkers Ju 86 bomber of 1934, Junkers abandoned the corrugated sheeting of his earlier designs. The basic layout was used in the four-engine Junkers Ju 89 heavy bomber, but this program ended with the death of Walther Wever, and his Ural bomber program along with him. Junkers then adapted the Ju 89 to passenger use, introducing the Junkers Ju 90, one of the first planes specifically designed for scheduled trans-Atlantic flights to the US. Developed in 1937, the aircraft suffered multiple setbacks with crashes of prototypes in 1937 and 1938. Further refinements enabled certification in 1939 and spurred South African Airways to make an initial order for two aircraft fitted with US-built Pratt & Whitney engines. Just as the aircraft was being readied for its first commercial flights, World War II began. With the outbreak of hostilities, all models were requisitioned by the Luftwaffe for military air transport roles, and later, long-range maritime patrol.

[edit] World War II

Military aircraft production was begun by the company in the 1930s and eventually monopolized all its resources. Perhaps the most notable design was the Junkers Ju 87 Stuka dive bomber, one of the Luftwaffe's most effective aerial weapons and continually used for bombing attacks as an integral part of the Blitzkrieg strategy. The Stuka was used for both precision tactical bombing and the strafing of enemy positions, acting as a sort of "airborne artillery" that was able to keep up with the fast-moving tanks and attack defended points long before traditional artillery could be brought into range. Later in the war it was fitted with a large cannon and employed in a "tank busting" role against Soviet armour. It gained much notoriety for its use at both Dunkirk and later Stalingrad, where it caused enormous destruction under Field Marshal Wolfram von Richthofen's VIII Air Corps.

Perhaps even more successful was the Junkers Ju 88, the primary light bomber of the German forces. It was used in practically every role imaginable; level bomber, shallow-angle dive bomber, night fighter and bomber destroyer and in anti-shipping raids. A variety of improved versions were also produced over the course of the war, including the Ju 188 and Ju 388 which included numerous features for better performance, but never replaced the Ju 88 outright. A much more formidable aircraft was also planned, the Junkers Ju 288, but the required high-power engines never worked and the effort was eventually abandoned.

A total of 4,845 Ju 52s were produced before and during the war. The wide availability of Ju 52s enabled their immediate utilization for the German war effort as a transport aircraft for delivering men and supplies. They were additionally used, with minor modification, to carry out bombing raids. Prior to World War II, the Ju 52 was utilized in the Spanish Civil War, where it took part in the Condor Legion's destructive raids on Durango and Guernica in 1937 which illustrated to the world - for the first time - the destructive potential and horror of strategic bombing. Unfortunately for its pilots and military passengers, by the outbreak of World War II, the Ju 52 was a thoroughly obsolete military design and unlike many other famous Luftwaffe aircraft, the Tante Ju was cumbersome, slow and therefore vulnerable to attack. This resulted in many losses, namely at Crete and Stalingrad.

Junkers also ran an engine factory, and in 1923 they separated it from the parent to form its own company, Junkers Motoren, or Jumo. This company expanded greatly in the 1920s and 30s, with factories spread across Germany. Jumo was the first German company to offer a truly modern engine suitable for aviation in the form of the 650 hp Jumo 210. But with the rapid advances in airframes, after a few short years this engine was considered to be underpowered causing Jumo to respond with the much larger Jumo 211. Perhaps unsurprisingly the 211 saw widespread use in Junkers bombers, but was little used otherwise, due largely to the better power output of the competing Daimler-Benz DB 601. Further development of the 211 led to the superb Jumo 213, which was in high demand for practically every late-war piston-engined aircraft. Their Jumo 004 jet engine was the first to be considered production quality and used in the then revolutionary Me 262 jet fighter.

The Junkers company survived the Second World War and was reconstituted as Junkers GmbH and eventually merged into the MBB consortium. Within West Germany, Junkers GmbH was engaged in research on the future of aerospace transportation during the fifties and early-1960s. During this period, Junkers employed the famous Austrian engineer and space travel theorist, Eugen Sänger, who in 1961 completed work for the design of an advanced orbital spacecraft at Junkers.

[edit] Junkers aircraft

Junkers W33
Junkers W33

[edit] Jumo engines

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[edit] References

  1. ^ Junkers Companies

[edit] External links

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