G.Haddow, P.Grosz The German Giants (Putnam)
In 1909 Dr. Johann Schutte and Dr. Karl Lanz founded the Luftschiffbau Schutte-Lanz at Mannheim to build airships for commercial and military purposes. Their successful venture subsequently led to the delivery of twenty airships to the German Army and Navy during the war, establishing Schutte-Lanz as the second largest supplier of airships to the German Armed Forces.
Following in the footsteps of so many German concerns, Schutte-Lanz began to experiment with a variety of aircraft types during the early years of the war. In late 1915 Dipl.-Ing. Wilhelm Hillmann, chief engineer of the Schutte-Lanz aircraft department, designed an all-steel R-plane at the request of Dr. Schutte. It was to be powered by four 300 h.p. water-cooled radial engines based on the Salmson-Canton-Unne engine, an example of which had been procured and improved upon by the Robur Motoren Gesellschaft, a Schutte-Lanz subsidiary. At the time the proposal was tendered the Robur engine was undergoing bench tests at the Flugzeugmeisterei in Adlershof. The 9000 kg. R-plane project, to be equipped with a 3•7 cm. machine cannon and jettisonable fuel tanks, did not receive a favourable reception from the military authorities, who considered the project too advanced. Schutte-Lanz lacked the financial resources of larger companies, such as Siemens-Schuckert and Staaken, and was forced to drop the project.
In October 1915 Schutte-Lanz established a branch works at Zeesen for two reasons: the need of more space, and the request of Idflieg that another airship works be erected in case of air raids on Mannheim. The new facilities were finished in April 1916, and large-scale aircraft production began when Schutte-Lanz (Schul) received a contract in October 1916 to build 250 Ago C.IV machines under licence. Shortly thereafter (winter 1916-17) as the VGO-Staaken types began to achieve frontline capability, Schutte-Lanz was given a contract for the construction of six Staaken R.VI aircraft under licence. At the time the contract was placed the myriad constructional details had not been entirely settled. As might be expected, continual changes and improvements by Staaken kept the final drawings in a state of flux, thereby delaying the construction of the licence machines. This delay was responsible for Idflieg's reduction of the original contract to three Staaken R.VI machines. The R.27, R.28 and R.29 were built by Schiitte-Lanz, the first of which was delivered in the latter part of 1917. All three R-planes were operational and were subsequently destroyed in crashes.
Three Staaken R.XIVa machines numbered R.84 to R.86 were under construction by Schutte-Lanz at the end of the war, and their status as of 15 January 1919 was as follows: The R.84 and R.85 were three-quarters completed and the R.86 parts were finished and final assembly had begun. The German Government gave permission to finish these machines as civil transport aircraft. Only the R.84 was completed, but it was soon scrapped along with the R.85 and R.86 in accordance with the Armistice treaty and to prevent them from falling into Allied hands. The cost of the R.84 to R.86 was 600,000 marks each. These aircraft varied from the Staaken-built R.XIVa machines only in detail.
Schutte-Lanz, by virtue of its experience in outfitting airships, also produced engine-room telegraphs (twenty were delivered) and bomb-release mechanisms for other R-plane manufacturers.
In the middle of 1917 the "Amerikaprogramm" came into being, and its execution became the responsibility of Idflieg. The programme's sole purpose was to strengthen the German air arm to meet the expected impact of American participation in the war. Although emphasis lay in the establishment of new fighter squadrons, the complement of the two R-plane squadrons was also to be increased. The net effect on Schutte-Lanz was that it, among other aircraft companies, received a contract to construct two all-duraluminium R-planes, designated the Schul R.I, numbered R.65 and R.66.
Although Dipl.-Ing. Hillmann had left Schutte-Lanz in April 1916, he continued to maintain close contact with Dr. Schutte and participated in the design of the R.I as a consultant. Hillmann recommended that the R.I incorporate the best features of two designs he had prepared for Schutte-Lanz: the central-engined G.IV and the twin-boom, three engined G.VI. As first proposed by Schutte-Lanz designers, the R.I was a rather ungainly aircraft characterized by sharply swept-back wings, a Staaken R.VI gunner's pulpit and cabin, very high and fully enclosed by windows; a biplane tail perched atop the tail booms and a massive combination twin-truck tandem landing gear equipped with an awkward total of sixteen wheel. At Dr. Schutte's request Hillman modified the proposed R.I to give it more pleasing aerodynamic lines.
The final R.I version, again slightly modified by Schutte-Lanz designers, included some features which Hillmann would have changed; namely, the rectangular wing planform and the insufficient rudder surfaces. It was a twin-boom biplane with a centre nacelle containing the pilots' cabin, navigator and wireless operator's positions, the bomb load and six 300 h.p. Basse und Selve BuS.IVa engines, the most powerful six-cylinder engine available for R-plane use at the time. The twin-boom layout was Schutte-Lanz' solution to the central-engine problem. Experience with previous central-engined R-planes had shown that large fuselages were not stiff enough to avoid resonance vibrations, bending and twisting. The same could be aid of wing-strut or outrigger mounted propeller supports: they had proved to be too flexible to assure fully reliable operation of the drive system. The Schutte-Lanz solution was to divide the fuselage into three parts: a relatively small, robust centre nacelle to concentrate engine and bomb weight in a compact structural framework which also afforded good manoeuvrability; and two outer booms to support the tractor propellers, the tail and the fuel tanks, which were separated from the engine to minimize fire hazard. In an emergency the fuel tanks could be jettisoned, and a gravity tank located in the top wing contained enough reserve fuel to enable the R.I to find a suitable landing spot. The nacelle and booms were built of U- and I- duraluminium profiles, cable-braced throughout and covered with doped fabric.
Most of the 13•2 metre long nacelle was filled with the six Basse und Selve BuS.IVa engines, leaving but 2 metres in the nose for the pilots' and navigator's cabin. Two engine pairs, separated by a catwalk, were located on each side of the nacelle. Each pair drove a tractor propeller through an individual cone-pawl clutch and common right-angle gear drive connected to a heavy transmission shaft leading out to the propeller gear-box. The remaining engine pair was mounted side by side in the nacelle rear and drove a pusher propeller through individual clutches and a common gear-box. Initially two superchargers driven off the centre gear-boxes were to have been supplied, but these were eliminated in the final version. Underneath the engines an enclosed bomb bay was fitted capable of holding a bomb load of approximately 1500 kg.
A crew of eight was to have been carried, and five machine-gun positions were provided: a ventral and dorsal turret in each tail boom abeam of the pusher propeller, and a turret in the top wing reached by climbing through a streamlined shaft. If necessary a 3•7 cm. machine cannon could be mounted in the commander/navigator's cockpit in the nacelle nose.
In contrast to the all-steel wing spars employed by Dornier and Junkers, the Schul R.I was the only R-plane to have duraluminium wing spars planned for it. In its airship work Schutte-Lanz had thoroughly investigated the structural properties of plywood, steel and dural profiles and had come to the conclusion that dural was superior, not only for aircraft but also for the last two Schutte-Lanz airships. Spars and ribs of the 44 metre wing were assembled from a combination of tubes and profiles riveted together. Both wings had a 2 degree dihedral and the bottom wing had sharp anhedral inboard of the tail booms, in order to shorten the landing gear and achieve some structural and aerodynamic advantages. Ailerons fitted to both wing were to have been aerodynamically balanced by a "flying" aerofoil or series of "flying" aerofoils suspended between the wings and connected in such a manner as to assist working the aileron controls. The device had been tested in a wind tunnel for both aileron and elevator compensation.
The twin booms supported the biplane tail, which, being held at the end of its span, could be made structurally lighter. An unusual feature of the tail was its three-piece elevator surfaces, a proposed solution to adjusting the angle of incidence of the tail. Fully tested in a wind tunnel, the centre elevator panel was to be used for "coarse" steering during a long climb or descent, while the two outer panels operated as conventional elevator surfaces to make small corrections. The rudders fitted at each end of the tapering booms, give an impression of being too small, and it is possible that a third was to be fitted in the centre of the tail planes.
According to Dipl.-Ing. Hillmann, the R.I was 80 per cent complete when the war ended. It was dismantled to prevent it from falling into Allied hands.
The Schutte-Lanz concern, unlike many of the German aircraft companies, survived the war and the depression. Using the skills it had developed in the processing of plywood and special adhesives for airships, it is today a leading German plywood manufacturer.
Type: Schutte-Lanz R.I
Manufacturer: Luftschiffbau Schutte-Lanz, Zeesen
Engines: Six 300 h.p. Basse und Selve BuS.IVa engines
Span, 44 m. (144 ft. 4 in.)
Chord, 5 m. (16 ft. 4 1/2 in.)
Gap, 4•9 m. (16 ft. 1 in.)
Dihedral, 2 degrees
Anhedral, 9 degrees
Incidence, 3 degree
Length, 22•97 m. (75 ft. 4 in.)
Nacelle length, 13•25 m. (43 ft. 5 1/2 in.)
Boom length, 17-4 m. (57 ft. 1 in.)
Boom centres, 10 m. (32 ft. 10 in.)
Height, 7•28 m. (23 ft. 10 1/2 in.)
Tailspan, 12•9 m. (42 ft. 4 in.)
Pusher propeller diameter, 4•8 m. (15 ft. 9 in.)
Tractor propeller diameter, 5•3 111. (17 ft. 4t in.)
Areas: Wings, 410 sq. m. (4412 sq. ft.)
Wings, 2,500 kg.
Tail unit, 310 kg.
Fuselage, 1,750 kg.
Undercarriage, 1,000 kg.
Engines, 2,850 kg.
Transmission, 990 kg.
Propellers, 300 kg.
Instruments, 550 kg.
Armament, 610 kg.
Empty, 10,860 kg. (23,946 lb.)
Fuel, 3,260 kg. (7,188 lb.)
Disposable load, 2,480 kg. (5,469 lb.)
Loaded, 16,600 kg. (36,603 lb.)
Wing Loading (Est.): 40•5 kg./sq. m. (8'3 lb./sq. ft.)
Performance (Est.): Unknown