Junkers Ju 90

The Junkers Ju 90 was a four-engined airliner and transport aircraft designed and produced by the German aircraft manufacturer Junkers.

Derived from the abortive Ju 89 strategic bomber, it was developed to be used as a long-distance commercial aircraft for the German flag carrier Deutsche Luft Hansa. It drew heavily upon the Ju 89, sharing the same wing and tail unit while adopting an all-new fuselage that could seat up to 40 passengers. In contrast to the corrugated skin traditionally used on Junkers aircraft, virtually all of the aircraft had a smooth duralumin covering. Various models of engines were used to power the type. Junkers' design team was headed by Ernst Zindel, and Professor Herbert Wagner.

On 28 August 1937, the first prototype performed its maiden flight; flight testing was undertaken in close collaboration with Deutsche Luft Hansa, who was sufficiently encouraged by the results to issue a production order. While the Ju 90 did enter limited service with the airline, the planned full scale passenger services envisioned were never enacted due to the outbreak of the Second World War. During the conflict, the civil Ju 90s were impressed into service with the Luftwaffe as military transports. They were active during the invasion of Norway and on the Eastern Front, where they supplied the German 6th Army that was besieged at Stalingrad. Luftwaffe Ju 90s were also operated in the Mediterranean for a time.

Several Ju 90s were rebuilt into prototypes for the Ju 290, a larger transport and reconnaissance aircraft. Just two Ju 90s survived the conflict and were scrapped shortly thereafter.

Design and development

Background

The origins of the Junkers Ju 90 are directly connected with that of the Ju 89, a prototype strategic bomber. This aircraft, which had commenced developing during the mid-1930s, was a contender in the Ural bomber programme that was aimed at creating a long-range strategic bombing capacity for the Luftwaffe. By the time that the Ju 89 programme had made it through to the flight testing phase, the development of four-engined bombers had become an increasing politically contentious matter, particularly following the untimely demise of General Wever (one of the programme's most powerful advocates) as well as rising tensions between Erhard Milch (another proponent) and commander-in-chief of the Luftwaffe, Hermann Göring. Recognising that strategic bombing was falling out of favour with the Reichsluftfahrtministerium (RLM) in favour of smaller and faster bombers, Junkers approached the RLM with their proposal to reuse the components intended for the third Ju 89 prototype to produce a transport aircraft for the German flag carrier Deutsche Luft Hansa instead.

The RLM consented to Junkers' proposal, but only on the basis that an alternative engine to the Ju 89's Daimler-Benz DB 600A V-12 engine was used on any subsequent aircraft. was relatively generous by the standards of the time, possessing an internal width of 2.83 m (9 ft  in).

In terms of its basic configuration, the Ju 90 was a four-engine all-metal low-wing aircraft fitted with twin end-plate vertical stabilizers.

The interior of the aircraft could be configured into various cabin layouts; when arranged to maximise occupancy, the carriage of up to 40 passengers was possible. This aircraft, named Preussen, was lost during a failed take off for tropical flight tests in November 1938 at Bathurst, Gambia.

Despite these setbacks, Luft Hansa opted to order eight production standard Ju 90A-1 aircraft. They also flew the next two prototypes, starting with V3 Bayern which flew on the Berlin-Vienna route from July 1938. This Trapoklappe ramp, when lowered, was powerful enough to raise the fuselage to the horizontal flying position. Both aircraft were retroactively fitted with the much more powerful, unitized Kraftei-mount 1,200 kW (1,600 hp) BMW 801MA radials, with the first suffix letter "M" signifying the initial Motoranlage format of unitized powerplant installation design promulgated by the RLM. Ju 90s were also used as tugs for heavy gliders.

thumb|Junkers Ju 90B-1 at [[Helsinki-Malmi airport in January 1944.]]

The two last prototypes – the V7 and V8 – fed directly into the Ju 290 development programme. The former had a fuselage extension of 1.98 m (6 ft 6 in) and the addition of dihedral to the tailplane to solve a yaw instability. A reconnaissance prototype aerodynamically similar to the V7, the V8 was armed, however, with two 20 mm MG 151/20 cannons and up to nine 13 mm (.51 in) MG 131 machine guns in two dorsal, one ventral, and one tail position.

The Ju 90 was used for the first time operationally during the invasion of Norway.

Ju 290 / 390 development

Several Ju 90s were converted into prototypes of the Ju 290, a larger aircraft intended for transport and reconnaissance duties. The more powerful engines and other modifications to the Ju 90 V5 and V7 were steps in this direction and the latter was converted into the Ju 290 V3. The Ju 90 V8 became the second prototype Ju 290 V2. The incomplete Ju 90 V11 airframe was converted into the Ju 290 V1. The Ju 90 V6 airframe was used in the construction of the Ju 390 V1.

Numbers and survivors

Just 18 Ju 90s of all versions were completed of which two survived the war, both captured, and then scrapped shortly afterwards.

Operators

;25px Germany

Luftwaffe
Deutsche Luft Hansa

Accidents and incidents

Specifications (Ju 90A-1)

thumb|Junkers Ju 90 3-view drawing from L'Aerophile October 1937

References

Citations

Bibliography

External links

Four Miles a Minute Sky Sleeper Sleeps Forty, January 1938, Popular Mechanics article with rare photos of JU-90V1 version and interior photos
WW2 in Color very good information on the JU-90 history