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Junkers R.I

Страна: Германия

Год: 1919

Junkers - F 13 - 1919 - Германия<– –>K.W. (Kaiserliche Werften) - Type 401 - 1914 - Германия

G.Haddow, P.Grosz The German Giants (Putnam)

Junkers R.I

   During 1917 plans were made to develop a series of high-performance R-planes capable of executing long-range daylight reconnaissance and bombing missions. The design of these aircraft represented a large step forward, and new construction techniques had to be developed to utilize the latest aerodynamic, structural and material advances. The projected aircraft were to be all-metal monoplanes with engines buried but still accessible in a thick cantilever wing. Contracts to build such aircraft were awarded to Junkers, Staaken, AEG and Dornier. Junkers, of course, was a pioneer and leader in all-metal aircraft construction and possessed ample experience to embark on the new task. The firm Junker & Co. had been founded by Professor Hugo Junkers, a brilliant, resourceful and prolific engineer. During his lifetime Junkers was awarded more than 1000 patents in varied fields, including all-wing aircraft, opposed-piston engines (basis for the Junkers Jumo engines), calorimeters, fin-type heat exchangers, water brakes and a new concept for heating water with gas. Junkers started his firm to manufacture gas water heater-bathtub combinations and was extremely successful in this effort.
   Junkers' initial contact with aircraft came when at the age of fifty he assisted Professor Reissner in designing his Ente monoplane. As a result of his experiences, Junkers received the famous patent for the all-wing aeroplane, and in 1912 he left his teaching post at the Technische Hochschule in Aachen to apply his talents to aerodynamic studies. Royalties obtained from licensing his many patents enabled him to build a small wind-tunnel and spend full time in research. When the war broke out he decided to put his theories to practice and systematically developed the Junkers J.1, which was built wholly from 0•1 mm. thick sheet steel and featured the thick wing which was to become a Junkers trade-mark. Several other Junkers types were built before the R-plane contract was placed by Idflieg for two R-planes on 17 November 1917.
   As expected, the Junkers R.I was evolved through a series of intensive structural and wind-tunnel investigations and was possibly the only R-plane that had a wind-tunnel pedigree. The design department had prepared several layouts, the first a monoplane with a 35 metre wingspan (27 March 1917) and the second a monoplane with twin rudders and a wingspan of 38•5 metres (probably middle 1918).
   The 35 metre version is generally referred to as the R.I numbered R.57/17 and R.58/17, although as design and wind-tunnel studies progressed the final version may have been more like the 38•5 metre project. The R.I (35 metre version) was characterized by a typical thick Junkers wing consisting of three sections; a centre section integral with the fuselage and two sharply swept-back removable outer sections. The 1•6 metre thick centre panel continued out just beyond the propeller shafts and enabled a mechanic to service the four 260 h.p Mercedes D.IVa engines buried in the wings. The engines were mounted side by side at right angles to the line of flight, and each pair drove a propeller through a clutch and right-angle bevel gear-box. Each bank of engines was equipped with two low-drag Junkers adjustable nozzle radiators placed in the slipstream along the upper wing contour. A 1000 litre fuel tank was mounted slightly behind each engine pair near the centre of gravity.
   The wing was different from all other R-plane in that it had no actual wing spars. Rather, the wing spar and rib section was formed by a lattice-work of diagonal metal tubes to which the corrugated duraluminium skin was riveted. This method of wing construction has high torsional stiffness for relatively light weight and provides superior resistance against gunfire, but it is more expensive to produce than wings constructed by conventional techniques.
   The slim, square fuselage was constructed from welded steel tubing covered with corrugated skin. A most noticeable feature was the oversize cockpit canopy for the two pilots, which, judging from its size, was also the aircraft commander/navigator's position. A long flat bomb bay capable of holding a 1500 kg. bomb load was located underneath the fuselage. Defensive armament consisted of seven machine-guns and cannon; one was placed in a conventional nose turret; two were located on either side of the fuselage a few feet behind the trailing edge of the wing; two were mounted in the upper wing surface above the engine gangway, and two protruded from beneath the wing outboard of the landing gear. The reason for the heavy defensive armament was that this project was intended to participate in daylight raids when chances of interception were greater.
   The tail surfaces, although aerodynamically balanced, were to be fitted with servo-motors to lessen the control forces but still transmit the "feel" of the controls to the pilots.
   The final design for the landing gear had not been prepared when Junkers ceased work on the R.I at the end of the war. Initial drawings show it as a simple triangular structure supporting twin-wheels. A wind-tunnel model of the R.I minus its undercarriage was tested during July 1917.
   Towards the end of 1917 Junkers and Fokker formed the Junkers-Fokker Werke A.G. to build all-metal aircraft. This merger was forced upon Junkers by the military authorities. They felt that Junkers, unlike Fokker, lacked mass-production experience, nor was he a pilot, an asset which counted highly in those days. But the two men had completely different characters and goals. Fokker was interested in wooden construction and could build a new type from scratch in a few weeks, whereas Junkers was an ardent investigator, thoroughly testing each concept before incorporating it in a design. New capital and personnel were brought into the Junkers-Fokker Werke, and the production of the Junkers J.1 ground-attack biplane continued more or less automatically. But neither Junkers nor Fokker were greatly enthused by the forced merger, and within a short time each withdrew to his own sphere of activities. Junkers still controlled his heating-apparatus plant, in which he continued his all-metal aircraft developments, culminating in the D.I (J.9), Cl.I (J.10) and Cls.I (J.11). The construction of parts for the R.I began in the Junkers & Co. heating-apparatus plant, where they were found by the Inter-Allied Control Commission inspection team in 1919.
   On the 15 March 1918 a list of projected delivery dates issued by Idflieg showed that it expected delivery of the first Junkers R.57 by June 1918, and the second, R.58, by August 1918. As it turned out, the Idflieg projection were over-optimistic, for the R.I was never completed and the various parts which had been assembled had to be destroyed after the Armistice.
   The second Junker R-plane project (38,5 metre span) differed greatly from the first, although the thick wing section was retained. The fuselage height was increased to 3•6 metre, a size which one is at a loss to explain. It was no longer square, but had an oval tail section and featured an extended nose fitted with a machine-gun turret. The pilots' seats were widely separated; their field of vision was restricted by the high fuselage, engine nacelles and long nose. To simplify the transmission gearing, the right-angle gear-box was eliminated and the engines were mounted in nacelles extending from the wing. Each nacelle contained two engines placed along the flight axis and coupled to drive a single propeller. The radiators were placed above the wing as in the first project. The twin rudders were mounted in the slipstream of the propellers.
   Hand in hand with the Dornier and Staaken R-monoplanes, the Junkers R.I provided a startling example of the advanced types of bomber aircraft the Germans were planning to place into service should the war have continued. The modern construction techniques embodied in the all-metal Junkers R.I pay tribute to a great pioneer of aviation and his insistence that new concepts should spring forth from the well of research.


Type: Junkers R.I. (35 metre version)
   Manufacturer: Junkers-Fokker Werke A.G., Dessau
   Engines: Four 260 h.p. Mercedes D.IVa engines
   Span, 35 m. (114 ft. 10 in)
   Length, 22•3 m. (73 ft. 2 in.)
   Height, 9 m. (29 ft. 6 in.)
   Tailspan, 12 m. (39 ft. 4 in.)
   Propeller diameter, 5 m. (16 ft. 5 in.)
   Wings, 200 sq. m. (2152 sq. ft.)
   Weights (Est.):
   Wings and fuselage, 2000 kg.
   Undercarriage and tailskid, 450 kg.
   Tail assembly, 200 kg.
   Engines, exhaust pipes, radiators, water, 2000 kg.
   Fuel and oil tanks, 210 kg.
   Propellers, gears, clutches and drive shafts, 750 kg.
   Engine accessories, 150 kg.
   Fuselage installations (machine-guns and cannon bomb racks, etc.), 240 kg.
   Empty, 6000 kg. (13,230 lb)
   Fuel, 1300 kg. (2867 lb)
   Bomb load, 1500 kg. (3307 lb.)
   Crew and remainder, 1200 kg. (2646 lb.)
   Loaded, 10,000 kg. (22,050 lb.)
   Performance (Est.):
   Maximum speed, 180 km.h. (112 m.p.h.)
   1000 m. (3281 ft.) in 4•6 mins.
   2000 m. (6562 ft) in 10•8 mins.
   3000 m. (9843 ft.) in 19 mins.
   4000 m (13.124 ft) in 33 mins
   5000 m. (16,405 ft.) in 76 mins.
   Ceiling. 5200 m. (17,061 ft)

Type: Junkers R (38,5 metre version)
   Manufacturer: Junkers-Fokker Werke A.G., Dessau
   Engines: Four 260 h.p. Mercedes D.IVa engines
   Span, 38•5 m (126 ft. 3 1/2 in.)
   Chord, 7 m. (22 ft. 11 1/2 in.)
   Length, 24 m. (78 ft. 9 in.)
   Height, 6•5 m. (21 ft. 4 in)
   Tailspan,8 m. (26 ft. 3 in.)
   Wheel track, 4•6 m. (15 ft. 1 in.)
   Propeller centres, 7 m. (22 ft. 11 1/2 in.)
   Maximum fuselage depth, 3•2 m. (10 ft. 6 in.)
   Maximum fuselage width, 2•2 m. (7 ft. 21 in.)
   Weights: Unknown
   Performance: Unknown

Junkers R-Flying-boat Project

   The realization of practical all-metal construction techniques greatly expanded the horizons of the aircraft designer. No longer fettered by the structural limitations of wood, the designer could begin to think in terms of size in a way which would have met with ridicule a few years earlier.
   In June 1918 Junkers proposed an all-metal R-flying-boat with the prodigious wingspan of 80 metres (262,5 feet). The flying-boat was to be powered by four 1000 h.p. Junkers engines, a development based on the experimental Junkers Fo.2 opposed-piston engine of 1916, the forerunner of the rugged Junkers diesel aircraft engines of later years. The R-flying-boat and 1000 h.p. engine remained on the drawing board, but their conception was a true measure of things to come. Junkers continued to design large aircraft in the post-war years; for example one behemoth proposed in 1921 had a wingspan of 110 metres. However, it was not until 1928 that the Junkers organization was able to construct its first really large aircraft, the 44 metre wingspan, all-metal G.38.


Type: Junkers R-Flying-boat Project
   Manufacturer: Junkers-Fokker Werke A.G., Dessau
   Engines: Four 1000 h.p. Junkers Diesel engines
   Span, 80 m. (262 ft. 5 1/2 in.)
   Chord, 12 m. (39 ft. 4 1/2 in.)
   Wing depth, 2-4 m. (7 ft. 10 in.)
   Length, 38 m. (124 ft. 8 in.)
   Height, 9 m. (29 ft. 6 in.)
   Tailspan, 12 m. (39 ft. 41 in.)
   Areas: Wing, 1000 sq. m. (10,760 sq. ft.)
   Weight: Loaded, 48,000 kg. (105,840 lb.)
   Wing Loading: 48 kg./sq. m. (9'8 lb./sq. ft.)

G.Haddow, P.Grosz - The German Giants /Putnam/
Wooden model of the Junkers R.I used for wind-tunnel tests.
H.Cowin - Aviation Pioneers /Osprey/
No resume of what Germany had up its sleeve in the way of bomber development would be complete without reference to the Adolf Rohrbach-designed Zeppelin-Staaken E 4250. The other obvious candidate for analysis is the long range Junkers R I, seen here. By October 1916, the German Army Air Service was very aware that it had no heavy bombers capable of carrying out daylight raids and sought industry proposals to remedy matters. Junkers put work underway on their R I in January 1917, the design being finalised in March of that year. What Junkers were proposing was a fully cantilevered monoplane with a 5-man crew and powered by four unspecified engines housed transversely within the thick wing's inboard sections. These paired engines supplied power through a combining gearbox to drive the bomber's two propellers. Performance estimates for the R I included a top level speed of 112mph, an operational ceiling of 17,060 feet and a maximum bomb load of 3,305lbs. Where the R I really came into its own was over its ability to carry a 2,200lb load of bombs over a radius of action of 380 miles. With wind tunnel testing complete and work underway on R 57/17, the first of the two machines ordered, the R I would have given the Allies pause for thought had it gone into service, particularly as even the first generation of lumbering biplane R-planes had proved exceptionally difficult to combat in operational service.
G.Haddow, P.Grosz - The German Giants /Putnam/
Junkers R.I. Engine and power transmission arrangement.
G.Haddow, P.Grosz - The German Giants /Putnam/
Junkers R.I project
G.Haddow, P.Grosz - The German Giants /Putnam/
Junkers 'R' project
G.Haddow, P.Grosz - The German Giants /Putnam/
Junkers R-flying-boat project