Junkers J 3

from Wikipedia, the free encyclopedia
Junkers J 3
Junkers J3
Type: Fighter plane
Design country:

German EmpireThe German Imperium German Empire


Junkers & Co.

First flight:

Canceled in 1916

Number of pieces:


The Junkers J 3 was a single-seat, experimental fighter aircraft in all-metal construction, in which Hugo Junkers first proposed the use of duralumin as a material in 1916 in order to reduce the weight of the all-metal construction.


A serious disadvantage of the first two Junkers constructions Junkers J 1 and Junkers J 2 was the heavy weight of the overall construction, which consisted of heavy iron sheets and pipes. From the point of view of the Air Force Inspection (IdFlieg), all-metal aircraft were therefore only useful as slow ground attack aircraft and observers, but not as fighter aircraft in fast and agile aerial combat. With the Junkers J3, Hugo Junkers wanted to prove that all-metal aircraft are also suitable for aerial combat. In April 1916, he commissioned his head of development, Otto Mader, at the Dessau Research Station to develop a small, single-seat experimental aircraft in all-metal construction that could meet the climbing performance and maneuverability requirements of fighter aircraft. For this purpose, Junkers suggested the use of duralumin , which had been manufactured in the Düren metal works since 1909 , which had been available in sufficient quantities for some time and promised a weight reduction of 60% compared to a conventional iron construction. The lower strength of duralumin had to be compensated for by the construction that Mader designed together with Reuter and Franz Brandenburg . Parallel to the development of the Junkers J3, Steudel investigated the production-side processes when using duralumin, as the methods known from steel and iron construction, such as B. welds to which lightweight construction could not be transferred.


Mader envisaged two different variants of the J 3 . The J 3-I was intended to be a single-seat fighter, while the two-seat J 3-II was to be used as an attack aircraft . A special feature of the construction was the use of corrugated iron as self-supporting planking. This was intended to compensate for the lower strength of the duralumin sheets. The underlying duralumin tube construction was made of steel at critical construction points. Instead of the Mercedes D III engine, the lighter Oberursel UIII rotary engine should be used. Also new in the design of the J 3 was the tripartite division of the wing, consisting of a wing center piece integrated into the fuselage and a right and left outer surface. The outer surfaces were attached to the wing center section using ball screw connections. The advantage of these ball screw connections was that the outer wings could be exchanged. The ball screw connections of the wings were found in almost all Junkers developments in the twenties. Since the welding technique was not easily applicable when using light metals , the rivet construction generally used later in aircraft construction was used for component connections on the J 3 .

Prototype construction

The development and prototype construction took place without any order from IdFlieg and was operated entirely at Junkers & Co.'s own cost and risk. In the run-up to the actual J 3 prototype construction, a wing was first made from duralumin and subjected to extensive load tests. By using duralumin instead of iron, the weight of the wing structure could be reduced by a third. Since the welding process used in the J 1 and J 2 was to be replaced by riveted joints in the J 3 , extensive experiments were carried out in the workshop on riveting processes in advance of the actual aircraft construction. For the first time, large-scale devices, so-called "construction gauges", were created that were supposed to ensure the production of dimensionally accurate sashes for later J 3 series production.

Construction work on the single-seater Junkers J 3-I began in the summer of 1916. By autumn 1916, the entire tubular frame and the corrugated sheet metal cladding of the wings had already been completed. Lack of funds and the looming IdFlieg order for the Junkers J 4 forced Hugo Junkers to stop work on the half-finished J 3 in October 1916 . From November 1916 Mader, Brandenburg and Steudel devoted themselves to the construction of the Junkers J 4 , which was also made of duralumin as a material and which later became the first all-metal aircraft in lightweight construction instead of the J 3 .

Hugo Junkers was only marginally involved in the development of the J 4 . After the design of the J 3 provided mathematical proof that the use of duralumin would lead to significantly lighter all-metal aircraft, Hugo Junkers devoted himself to further designs of fighter aircraft, from the J 3 to the Junkers J 5 - and Junkers J 6 - Designs finally led to the first prototype of an all-metal fighter in the form of the Junkers J 7 . The two-seat variant J 3-II , which did not get beyond the design stage, was the initial draft for the later two-seat Junkers J 8 and Junkers J 10 fighter aircraft .


Although the Junkers J 3 was not completed, the building of the prototype laid the decisive foundations for future light aircraft construction. The future riveting processes in aircraft construction, fixture construction and the basic design criteria for light metal aircraft resulted from their development .

Numerous design elements of the J 3 , such as ball screw connections, corrugated sheet metal and self-supporting planking, remained defining features of Junkers constructions in the Junkers designs from the twenties up to the Junkers Ju 52 .

The Junkers J 3 was the world's first construction of a light metal aircraft .

Technical specifications

Parameter Data J3-I Data J3-II
crew 1 2
length 7.70 m 8.40 m
span 13.00 m 15.00 m
height 3.10 m
Wing area 21.00 m²
Empty mass 518 kg
Takeoff mass 770 kg
Top speed 190 km / h
Climbing time to 2000 m 4 min
Service ceiling 6480 m
Range 170 km
Engine 1 × Oberursel U III, 114 kW



The half-finished Junkers J 3 was stored in Dessau with the Junkers J 1 and several Junkers J 2 after work was stopped in October 1916 . In the mid-twenties, these aircraft were brought to the newly emerging Junkers teaching show to document the early phase of all-metal aircraft construction. The Junkers J 3 was part of the Junkers teaching show until the end of the war. Some sources report that the J 3 was destroyed in a bombing of the Junkers works. Other sources report that the Americans removed the teaching exhibition before Dessau was evacuated. The trace of the world's first usable light metal aircraft design and prototype is thus lost towards the end of the Second World War.

See also

Web links

Commons : Junkers J 3  - collection of pictures, videos and audio files

Individual evidence

  1. E. Unger, E. Schmidt: Duralumin . In: Flight . August 26, 1920, p. 933-935 .
  2. ^ Olaf Groehler , Helmut Erfurth: Hugo Junkers - a political essay . In: Military history sketches . 1st edition. Military Publishing House of the German Democratic Republic, Berlin 1989, ISBN 3-327-00677-6 , p. 21 .
  3. Junkers Flugzeug- und Motorenwerke AG (Ed.): The Junkers-Lehrschau . 2nd Edition. Dessau 1939, p. 35 .
  4. Wolfgang Wagner: From the J1 to the F13 . In: History of German aviation technology . Leuchtturm-Verlag, Konstanz 1976, ISBN 3-88064-015-7 , p. 33 .
  5. Junkers Flugzeug- und Motorenwerke AG (Ed.): The Junkers-Lehrschau . 2nd Edition. Dessau 1939, p. 116 .
  6. Junkers.de
  7. Paul Zoeller: The last Junkers aircraft I . BoD, Norderstedt 2017, ISBN 978-3-7448-0050-1 .