Junkers Ju 90
| Industry | Aerospace |
|---|---|
| Founded | 1895 |
| Headquarters | Dessau , Germany |
Key people | Ernst Zindel, Herbert Wagner |
| Products | Aircraft including Junkers Ju 90 |
The Junkers Ju 90 was a transport and airliner aircraft powered by four engines, developed by the German company Junkers. It evolved from the abandoned Junkers Ju 89 strategic bomber project, intended as a long-distance commercial airliner for Germany’s national airline, Deutsche Luft Hansa. While it utilized the wing and tail design of the Ju 89, the Ju 90 introduced a redesigned fuselage capable of seating up to 40 passengers. Departing from Junkers' earlier corrugated metal skin, this model featured a smooth duralumin exterior. The series was equipped with multiple engine variants. The development team was headed by Ernst Zindel alongside Professor Herbert Wagner.
The initial prototype took to the skies on 28 August 1937. After flight evaluations conducted with Deutsche Luft Hansa, a production contract was secured; nevertheless, extensive passenger service was limited due to the onset of the Second World War. During wartime, civilian Ju 90s were requisitioned by the Luftwaffe and operated as military transports, playing roles in the invasion of Norway and delivering supplies to the encircled German 6th Army at Stalingrad on the Eastern Front. They were also active in Mediterranean operations.
A number of Ju 90 airframes were adapted into prototypes for the larger Junkers Ju 290 transport and reconnaissance aircraft. Only two Ju 90 units survived World War II and were dismantled shortly thereafter.
Background
The Junkers Ju 90 was derived from the Ju 89, a mid-1930s prototype strategic bomber created under the Luftwaffe's Ural bomber initiative aimed at long-range bombing missions. By the time flight testing began on the Ju 89, shifting political dynamics and changes in leadership—including General Walther Wever’s death and conflicts between Erhard Milch and Hermann Göring—diminished backing for large four-engine bombers. With strategic bombing losing priority at the Reichsluftfahrtministerium (RLM) in favor of smaller, faster aircraft, Junkers proposed transforming components from the third Ju 89 prototype into a transport plane for Deutsche Luft Hansa.
The RLM granted approval on condition that an alternative to the Ju 89’s Daimler-Benz DB 600A V-12 engines be selected. This led to a design retaining the Ju 89’s wings and tail but introducing a broader fuselage tailored for passenger use. Built mainly from duralumin with some steel elements, the rectangular fuselage provided an internal width of 2.83 m (9 ft 3½ in), which was spacious compared to contemporaries.
The Ju 90 featured four engines mounted on an all-metal low-wing airframe with twin end-plate vertical stabilizers. Its wings were constructed around five tubular girder spars covered by smooth stressed skin; leading edges were distinctly swept while trailing edges remained almost straight. The aircraft incorporated Junkers’ "double wing" system with full-span movable flap and aileron surfaces. The tailplane included separate elevators forming another double wing arrangement, with fins and rudders located at each tailplane tip. Only the rudders and rear elevator sections retained Junkers’ characteristic corrugated skin; all other surfaces were covered with flush-riveted smooth duralumin.
The interior could be arranged in multiple cabin configurations accommodating up to 40 passengers at maximum capacity. Facilities included lavatories, a cloakroom, storage for air mail behind the passenger area, and a forward baggage compartment. The fully retractable tailwheel undercarriage had hydraulically operated single-wheel main gear units housed within the inner engine nacelles.
Entry into aviation and commercial service
The initial prototype, Ju 90 V1, completed its first flight on 28 August 1937, equipped with four Daimler-Benz DB 600C liquid-cooled inverted V engines, each generating 820 kW (1,100 hp). These powerplants surpassed those used on the earlier Ju 89 and subsequent Ju 90 production models. Bearing the name Der Grosse Dessauer, this aircraft underwent comprehensive flight evaluations with Deutsche Luft Hansa before being lost during overspeed testing in February 1938.
The second prototype (V2), delivered to Luft Hansa in May 1938, was powered by four BMW 132 radial engines rated at 620 kW (830 hp) each, reflecting a shift as Daimler-Benz concentrated on engines for frontline combat aircraft. Known as Preussen, it was destroyed in a failed takeoff during tropical trials at Bathurst, Gambia, in November 1938.
Despite these setbacks, Luft Hansa placed orders for eight production-standard Ju 90A-1 units and operated prototypes such as V3 Bayern on routes including Berlin to Vienna starting July 1938. By April 1940, seven Ju 90A-1s had been delivered; one was allocated directly to the Luftwaffe. The outbreak of World War II curtailed full passenger operations, with the majority of Ju 90s conscripted for military use—though two aircraft returned to civilian service with Luft Hansa.
The Ju 90 also garnered international interest; South African Airways ordered two Ju 90A-1s fitted with Pratt & Whitney Twin Wasp engines producing 670 kW (900 hp) each. These were planned for delivery in summer 1939 but never reached their destination.
In July 1941, the fourth prototype V4 entered Luftwaffe service, powered by Jumo 211F/L engines delivering 980 kW (1,320 hp). Early Ju 90A models featured five pairs of rectangular cabin windows per side; however, later Ju 90B prototypes (V5–V10) adopted circular portholes. The Ju 90 V11 served as the basis for the definitive Ju 290 prototype, which incorporated smaller rectangular windows.
The Ju 90B variants were distinguished by oval-shaped tail fins. Several prototypes were converted into the larger Ju 390 series: V6 was transformed into Ju 390 V1; V9 became Ju 390 V2 (redesignated Ju 390A-1 in October 1944); and conversion work on V10 into Ju 390 V3 commenced but was abandoned in June 1944. Junkers received compensation following order cancellations for seven partially completed Ju 390 airframes.
Transition to military application
In April 1939, the Reichsluftfahrtministerium (RLM) tasked Junkers with adapting the Ju 90 for military transport roles. The prototypes Ju 90V5 and V6 incorporated a redesigned wing with a wingspan increased by 19% and wing area expanded by 11%, reinforced landing gear featuring twin main wheels, and more streamlined vertical stabilizers without the previous horn balance cutout. The earlier large windows were replaced by ten small portholes on each side. The first flight of the Ju 90 V5 occurred on 5 December 1939. Both V5 and V6 were equipped with a powered rear fuselage loading ramp ('Trapoklappe') capable of elevating the fuselage to a horizontal position for vehicle and heavy cargo loading. These aircraft were upgraded with more potent unitized Kraftei-mount BMW 801MA radial engines delivering 1,200 kW (1,600 hp), consistent with RLM's Motoranlage engine configuration standards. Additionally, Ju 90s served as tugs for large gliders.
The final prototypes, V7 and V8, directly influenced the development of the Ju 290. The V7 featured a fuselage lengthened by 1.98 meters and incorporated tailplane dihedral to mitigate yaw instability issues. The armed reconnaissance variant V8 was fitted with two MG 151/20 cannons of 20 mm caliber and up to nine MG 131 machine guns of 13 mm caliber positioned around the airframe.
The Ju 90 entered operational service during the invasion of Norway. As part of the Luftwaffe transport fleet, it subsequently supported the encircled German Sixth Army at Stalingrad on the Eastern Front before redeployment to Mediterranean operations through late 1943.
Development of Ju 290 / 390
A number of Ju 90 airframes were adapted to serve as prototypes for the larger Ju 290, intended primarily for transport and reconnaissance missions. The evolution from Ju 90 V5 and V7 models played a key role in this progression, with the Ju 90 V7 ultimately becoming the Ju 290 V3. Additionally, the Ju 90 V8 was redesignated as the Ju 290 V2. The unfinished Ju 90 V11 fuselage was transformed into the Ju 290 V1, while the structure of the Ju 90 V6 was utilized in constructing the Ju 390 V1.
Production figures and remaining examples
A total of only eighteen Ju 90 aircraft across all versions were manufactured. Of these, two survived through World War II but were subsequently seized and dismantled shortly after the conflict. The remains of a Ju 90 shot down on July 23, 1943, near Bastia in northern Corsica, are still accessible to scuba divers; approximately two-thirds of the wreckage remains intact as of 2023.
Operators
Accidents and incidents
Bibliography
Further reading
External links
- Four Miles a Minute Sky Sleeper Sleeps Forty, January 1938, Popular Mechanics article featuring rare photographs of the JU-90V1 variant along with interior shots
- WW2 in Color comprehensive details on JU-90 historical background