A.Kay Junkers Aircraft and Engines 1913-1945 (Putnam)

Junkers J2

  Since the experimental J1 monoplane had shown itself to be faster than any German fighter and could probably survive more battle damage than the usual wood and fabric aircraft, further development was warranted. The most important modifications were to redesign the way the wings were attached to the fuselage and to pare down the weight of the airframe. By moving the wings forward of the pilot’s cockpit, it was possible to build the wing centre section as an integral part of the fuselage structure with four threads on each side to which the outer wing panels could be attached. This was achieved by means of threaded collars reminiscent of pipe connections. The tube ends of these connections had male and female conical ends to ensure a strong, aligned fit. It is not difficult to see that this idea was inspired by the pipework used in Junkers’ heaters and other equipment.
  The J2 was even more streamlined than the J1, had the engine totally enclosed and was skinned with thin, sheet iron without external bracing. The undercarriage struts were streamlined, with a small inter-wheel plane surface, and there was an engine radiator beneath the cockpit. The control surfaces were similar to those of the J1, and there was a roll bar to protect the pilot in the event of the aircraft overturning on the ground. The Mercedes D II 120hp engine was used again, driving a two-bladed airscrew, and one LMG 08/15 machine gun was to be fitted.
  Seven or eight examples of the J2 fighter were ordered by the Inspektion der Fliegertruppen (Idflieg). The first (E 250/16) made its maiden flight on 11 July 1916 from Doeberitz (there being no airfield at Dessau at that time) with Lt Mallinkrodt as the pilot. This was the prototype of the first all-metal fighter, but flight tests indicated that desirable modifications should be made to subsequent machines. These included a considerable increase in power to 160hp, which was achieved by using the Mercedes D III engine, an increase of 0.7m (2ft 3in) in wing span, a reduction of wing area by 84cm2 (13 sq in), ailerons of longer span and shorter chord, a slight increase of the fuselage length and a revision of the forward fuselage contours. The next five aircraft (E 251/16 to E 255/16) were thus modified, and there was possibly a sixth machine also. From the third machine onwards, a revised rudder with a semi-circular forward edge giving some aerodynamic balance was fitted.
  So modified, the J2s showed good handling characteristics and a speed about 15kph (9mph) higher than that of the best contemporary fighters. However, the climb rate was not adequate for combat, again owing to the weight, and the pilot’s all-round vision was not good. Moreover, the required endurance of five hours and the agility needed could not be given. Because of these shortcomings in an otherwise excellent design - and one which presaged things to come - no further orders were received. Matters were not improved when the second prototype (E 251/16) crashed following a low-level stall on 23 September 1916, killing the pilot Max Schade.


Data (definitive aircraft): Span 11.75m (38ft 6 1/2in); length 7.45m (24ft 5 1/2in); height 3.13m (10ft 3in); wing area 24.64m2 (265 sq ft); empty weight 1,020kg (2,249lb); loaded weight 1,165kg (2,569lb); max. speed 185kph (115mph); time to 3,000m (9,840ft) 21min; range 240km (149 miles).



Junkers J3

  The main lesson learned from work on the J2 was that weight needed to be reduced in order to achieve good climb and turning performances. Therefore, during 1916, Junkers turned its attention to the use of Duralumin lightweight alloy instead of iron, and work began on the J3. The design of the J3, which was to appear in the form of both a single-seat fighter and a two-seat observation aircraft, was undertaken by Mader, Reuter and Brandenburg, while engineer Steudel was in charge of the development of new production technologies for Duralumin. The aircraft had a welded, tubular structure with a light Duralumin covering which, for the wings at least, was corrugated to give lightness with rigidity. Once again the outer wing panels were attached by threaded collars (but with ball-and-socket joints) to a short centre section built integrally with the fuselage structure. Absence of interest from Idflieg led to this aircraft construction being closed down before completion because of a lack of funds, and the airframe was put on display at the Junkers Lehrschau until the end of the Second World War.


Data (J3 fighter): Span 11.45m (37ft 6 3/4in); length 6.65m (21ft 9 3/4in); wing area 21.0m2 (226 sq ft); empty weight 570kg (1,257lb); loaded weight 770kg (1,698lb); max. speed 180kph (112mph); range 170km (105 miles).

O.Thetford, P.Gray German Aircraft of the First World War (Putnam)

Junkers J 2
   As a development of the J 1, six J 2s (also designated E I) were built in 1916. Serials 250/16 to 255/16 were allocated, 252/16 having the more powerful 160 h.p. Mercedes D III engine fitted. Engine 120 h.p. Mercedes D II. Span, 11 00 m. (36 ft. 1 1/8 in.). Length, 7.3 m. (23 ft. 11 3/8 in.). Height, 3.13 m. (10 ft. 3 1/4 in.). Area, 19.84 sq.m. (214 sq.ft.). Weights: Empty, 1018 kg. (2,240 lb.). Loaded, 1,160 kg. (2,486 lb.). Speed, 145 km.hr. (90.625 m.p.h.). Armament, one Spandau machine-gun.

Junkers J 3
   Scheduled as a further development of the E type monoplanes, the J 3 would have been the first machine to be covered with the famous corrugated sheet covering. Although the airframe was never completed, the remains were preserved, as may be seen in the illustration, which also gives a good idea of the tubular basic framework of these Junkers machines. A rotary engine was scheduled for installation, and the span was 11.0 m. (36 ft. 1 1/8 in.).

W.Green, G.Swanborough The Complete Book of Fighters

JUNKERS J 2 Germany

   Following the successful demonstration in December 1915 of the Junkers J 1 all-steel two-seat experimental aircraft, Junkers und Compagnie of Dessau was awarded a contract by the Inspektion der Fliegertruppen (Idflieg) on 31 January 1916 for six examples of a single-seat fighter derivative, the J 2. The first example, powered by a 120 hp Mercedes D II water-cooled engine and carrying an armament of one LMG 08/15 machine gun, was flown at Doberitz on 11 July 1916. As a result of flight trials, a number of changes were introduced on the subsequent five aircraft which were powered by the 160 hp Mercedes D III engine. Overall length was increased marginally, wing span was extended by 27 1/2 in (70 cm), wing area reduced by 9 sq ft (84 cm2), long-span, shorter-chord ailerons were fitted and the forward fuselage contours revised. In its definitive form, the J 2 was 9 mph (15 km/h) faster than the best contemporary fighter and its handling characteristics were good, but because of the weight of its all-steel construction, climb rate was below the then current combat requirements. View from the cockpit was considered inadequate, and Idflieg coolness towards the fighter increased still further when a J 2 crashed on 23 September 1916, killing test pilot Max Schade. No further examples were ordered in consequence. The following data relate to the definitive model.

Max speed, 124 mph (200 km/h).
Time to 9,840 ft (3 000 m), 21 min.
Empty weight, 2,244 lb (1018 kg).
Loaded weight, 2,568 lb (1165 kg).
Span, 38 ft 4 2/3 in (11,70 m).
Length, 24 ft 4 1/2 in (7,43 m).
Height, 10 ft 3 1/4 in (3,13 m).
Wing area, 204.52 sqft (19,00 m2).