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

Zeppelin Staaken R VI

   Without doubt the most remarkable aircraft built by the Germans during the First World War were the "R" (Riesenflugzeug) type giant machines with four, five or six engines. The eventual degree of reliability that was attained was a noteworthy achievement when it is considered that everything connected with these unique aircraft had to be developed and produced from scratch. There was no previous experience in the design of aircraft of such gargantuan proportions. As an example of just one of the many difficulties, which had to be faced, that of engine failure may be instanced. Many of the first engines fitted in the Giants had been used with excellent reliability in airships, but in the aircraft they blew up (often literally) with monotonous regularity. This failure was eventually discovered to be due to the fact that the engines were called upon to produce upwards of 1,200 r.p.m. for considerable periods on take-off and climb, whereas in airship installation they were never-or rarely-called upon for more than a steady 800 r.p.m.
   Undercarriage problems too were a constant headache, again due to there being no previous material of this size to draw upon and the fact that stressing problems were not fully understood. However, mainly trial and error and "guestimated" experiments brought a degree of reliability. A.E.G., D.F.W., Linke-Hofmann, S.S.W. and Zeppelin Staaken all built original designs, but it was only the latter firm's machine that was developed into a series production type, this being the R VI. All others remained prototypes, but the majority of these also saw operational service in varying degrees.
   The Zeppelin Staaken R types had been developed, with varying engine permutations, from the V.G.O. I, which first flew in April 1915, to the R VI, in which production version it had four 245 h.p. Maybach or 260 h.p. Mercedes engines mounted in tandem pairs. The Zeppelin Fluzeugbau had moved to Staaken, near Berlin, in the summer of 1916, having transferred from Gotha-Ost, and it was there the majority of the building and development work was carried out.
   Of the eighteen R.VIs completed (R 25-39 and R 52-54), six were built by Aviatik, seven by Schutte Lanz and four by O.A.W. All except R 30, which was an experimental supercharged model, saw operational service with Riesenflugzeugabteilungen 500 and 501 on the Western Front and operated from the Ghent area.
   Construction of these monster machines, which spanned almost 140 ft., was a complicated and lengthy process, and the total number of man-hours must have been prodigious. A brief technical description follows, but for truly comprehensive coverage of these aircraft the serious student is referred to The German Giants, by Haddow and Grosz.
   The fuselage was of wooden construction and basically a fabric-covered, braced, box-girder. The upper longerons were in a horizontal plane on a level with the airscrew axis for almost the whole of their length. The lower longerons were parallel as far back as the gun position, where they swept up in a straight taper to join the upper longerons in a horizontal knife-edge. A gun position was provided in the extreme nose, and in this cockpit the bomb- release gear was located. Aft of this position the two pilots sat side by side with dual wheel controls, followed by the radio operator's and navigator's compartments. On a level with the leading edges of the wings, provision was made for a mechanic, who was mainly responsible for controlling the emptying of the eight cylindrical fuel tanks so that trim was not upset. The spacious dorsal cockpit accommodated two gunners, who were also able to fire below the fuselage through a ventral position in the floor. The section of space for stowage of eighteen 100 kg. bombs with a through passageway in order to communicate with the fore part of the fuselage.
   Of vast proportions, the wings were otherwise of orthodox construction and based on two main spars, which were of double box-girder section. The center panel of both wings extended as far as the engine nacelles and was without dihedral, as was the whole of the upper wing. The outer panels of the lower wing had marked dihedral. Taper on the wings was slight and on the leading edges only. Steel-tube compression members were positioned at interplane strut locations. The ribs were closely spaced and built-up lattice-girder structures, with top and bottom spruce flanges held together by double-lath web strips disposed zig-zag fashion. Ailerons were of steel-tube framework and, being unbalanced, must have demanded considerable muscle power-small wonder two pilots were required. All wing surfaces were fabric covered.
   Streamlined engine nacelles of alloy stringers and panels were supported by twin "A" frames of steel tube located at the spar stations, to which, in turn, the engine bearers were attached by a complex frame of sheet steel and wood. The tandem-mounted engines were fitted with gear-boxes, and the airscrews of the rear engines were driven through extension shafts. A small cockpit was located between the engines wherein the flight mechanic endured his lonely vigil. All struts were of circular-section steel tube faired off with three-ply sheet.
   An unusual feature of the Zeppelin Staaken R.VI was the wide use of aluminum in the construction of the tail. This was a huge biplane structure, the size of a single-seat fighter, with a swept leading edge to the tailplanes and inverse taper at the tips of the unbalanced elevators. The tailplane section was of a reverse camber. The triple rudders were the only control surfaces to be balanced, and all were fitted with fixed fin surfaces.
   Although no less than eighteen wheels were used in the undercarriage, all three chassis were relatively simple vee-type structures. The axles of the main chassis, located immediately under the engine nacelles, were thicker than those of a railway wagon and supported two pairs of twin wheels each end, which must have caused considerable drag. Axles were bound to the steel-tube vees with elastic cord. The tailskid was a conventional component fabricated from a single piece of ash and shod with steel.
   June 1917 saw the delivery of the first Staaken R.VI "R 25", soon to be followed by "R 26" in July. Many and varied were the sorties made by these Giant aeroplanes, including a considerable number of attacks on England, the first being on 17th September 1917, and even a raid on Le Havre, which involved a round trip of some 800 km. For a raid of this length a reduced bomb load was carried, probably in the nature of 750 kg. All bomb loads were in direct proportion to the fuel carried, which again was related to the range required. For raids of short duration 2,000 kg. of bombs could be carried, but the average load for a long-range sortie was about half that weight. The 100 kg. bombs were stowed internally, but the larger 300 and 1,000 kg. bombs (which were the largest bombs to be dropped from any aeroplane during the First World War) were carried under the belly, only partially enclosed.
   The R 25, the first of the Staaken R.VIs to be supplied, made an intrepid solo raid upon London during the night of 17th/ 1 8th February 1918, and with considerable skill scored a direct hit upon St. Pancras railway station. R 26 succeeded in making no less than twenty varied sorties, during which a total of some 26,000 kg. of bombs was dropped.
   The R.VI, R 39, was one of five Giants raiding England on the night of 16th - 17th February and dropped the first 1,000 kg. bomb on Britain, hitting the Royal Hospital, Chelsea. The same aircraft dropped the second 1,000 kg. bomb on the night of 7th - 8th March 1918, destroying houses in Warrington Crescent, Maida Vale.
   Rfa 501 made a total of eleven raids on England between 18th December 1917 and 20th May 1918. They dropped 27,190 kg. of bombs (compared with 84,745 kg. dropped by Gothas in twenty-two raids) and lost no aircraft due to Allied action.
   A seaplane variant of the R.VI was built for the Navy.
  
  
Description: Multi-engined giant bomber. Crew of seven.
Manufacturers: Zeppelin Werke Staaken G.m.b.H. Staaken bei Berlin (Staak.).
Sub-contractors: Automobil und Aviatik A.G., Leipzig-Heiterblick
   Ostdeutsche Albatros Werke G.m.b.H.,
   Schneidemuhl Luftfahrzeugbau Schutte-Lanz, Mannheim.
Power Plant: Four 245 h.p. Maybach Mb IV 6-cylinder in-line water-cooled engines.
   or
   Four 260 h.p. Mercedes D.IVa, 6-cylinder in-line water-cooled engines.
Dimensions
   Span 42.2 m. (138 ft. 5 5/8 in.)
   Length 22.1 m. (72 ft. 6 1/4 in.)
   Height 6.3m. (20 ft. 8 in.)
   Area 332 sq.m. (3,595 sq.ft.)
Weights
   Empty 7,921 kg. (17,426 lb.)
   Loaded 11,848 kg. (26,066 lb.)
Performance:
   Max speed 135 km.hr. (84.35 m.p.h.)
   Climb 3,000 m. (9,840 ft.) 43 min
   Ceiling 4,320 m. (14,170 ft.)
   Duration 7-10 hr.
Armament: Four manually operated Parabellum machine-guns in nose,
   dorsal and ventral positions.
   Various bomb loads carried to suit tactical or strategic requirement.

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

Staaken R.VI

   The development cycle of the Staaken R-planes reached its first plateau with the introduction of the Staaken R.VI. This aircraft was not only the largest aircraft to go into quantity production during World War I but it was also the best known of all the German R-planes. In all, a total of eighteen R.VI machines were constructed (excluding the seaplane versions), but only six of these were actually produced by the parent company. The remainder were manufactured under licence by the following firms: Automobil & Aviatik A.G., Leipzig-Heiterblick; Luftschiffbau Schutte-Lanz, Zeesen and the Ostdeutsche Albatroswerke G.m.b.H., Schneidemuhl.
   As one would expect, the design of the R.VI drew heavily on the earlier Staaken types, with the exception that the fuselage-mounted engine or engines were discarded in favour of four tandem push-pull engines installed in the nacelles. This configuration had not been tested in any Staaken machine prior to the R.VI, but the change was dictated by operational experience.
   The large-diameter nose propeller required a fairly high landing gear, which in turn increased the chances of nosing over during hard landings on rough terrain. Furthermore, the nose engine was thought to increase the danger of fire due to the proximity of the fuel in the fuselage.
   From a military standpoint, it was imperative that R-plane construction be accelerated. For this reason, it was decided to eliminate the complex and costly gear-box-coupled engine arrangement, which had not proved entirely reliable and required highly-trained crews to operate. Expert maintenance was responsible for the successful operation of the coupled system in the R.IV, but with the installation of higher-powered engines, the mechanical reliability dropped appreciably. Consequently, a simple push-pull tandem engine arrangement was chosen which became a standard fixture on subsequent Staaken aircraft.
   By the middle of 1916 exhaustive tests on the efficiency of tandem propeller arrangements had been completed by the Zeppelin-Werke Lindau (Dornier), and test results showed that tandem propellers were almost as efficient as propellers operating alone. This information was undoubtedly passed on to the Staaken branch of the Zeppelin combine and played its part in the development of the R.VI.
   The first R.VI, the R.25, was probably completed during the latter half of 1916 and was extensively test-flown by Staaken and Army engineers before being delivered to the air service on 8 June 1917. It was followed closely by the R.26, which was delivered on 20 July 1917. The success of the trials led to the awarding of licence contracts to Aviatik, Schutte-Lanz and Ostdeutsche Albatroswerke during the winter of 1916 and the spring of 1917.
   Because the construction particulars of the Staaken R.VI are common to most of the Staaken aircraft, they are described in greater detail in this section. The R.VI was powered either by four 260 h.p. Mercedes D.IVa engines or four 245 h.p. Maybach Mb.IVa engines. Judging from company records, the R.25 to R.38 were initially powered by Mercedes engines, but several of these machines were later fitted with Maybach Mb.IVa engines. The latter was one of the first "overcompressed" engines developed by the Germans for altitude use. The Mb.IVa had finished tests in the special high-altitude chamber at the Maybach factory in August 1916 and was offered to the Government in October 1916. The engine was designed to give full power at 2000 metres altitude by increasing the cylinder bore and the length of the piston, which raised its compression ratio. The Mb.IVa could not be run at full power below 2000 metres due to premature ignition of the fuel mixture, which resulted in harmful overheating of the engine. Its power output of 2000 metres was rated at 245 h.p., which would be equivalent to the output of a standard 300 h.p. engine at that altitude. A special stop prevented unintentional opening of the throttle at lower altitudes. The reason that the Mb.IVa was designated as a 260 h.p. engine in many official records has been explained as follows: "The 260 h.p" designation was applied to the 245 h.p. Mb.IVa so that it would not, as a new engine, appear inferior in horse-power to the older 260 h.p. engines which it replaced."
   The engines were mounted in the front and rear of each nacelle and independently drove a single propeller through a reduction gear-box and short transmission shaft. The rear engine shaft was longer than the front to place the pusher propellers clear of the trailing edges of the wing. The engine was separated from the gear-box by a combination leather-metal knuckle coupling to absorb vibrations and misalignments. Gear-box oil was cooled by a small semicircular cooler which extended into the slipstream below the nacelle.
   Four radiators were mounted on struts above the nacelles and, as on previous machines, the rear radiator was located higher than the front. The radiators used on the R.VI varied, and included those built by Windhoff, N.I.W, and Daimler.
   The engines were equipped with self-starting mechanism because "swinging the propeller" by hand was obviously impractical. The Mercedes engines were fitted with a simple Bosch electric starter powered by an accumulator. The Maybach engine were equipped with a novel self-starting device unique to that engine. The procedure consisted of pulling a lever which simultaneously lifted exhaust and intake valves and closed a shutter in the exhaust manifold. By action of a large hand suction pump connected to the exhaust manifold, fuel was drawn into the cylinders from the carburettor. When the engine was primed the valves were returned to their original position, and ignition was then effected by means of a Bosch hand-starter magneto. At a later date a field modification made by the R-plane squadrons was the addition of the Staaken hand-cranking device to facilitate the drawing of fuel into the cylinder.
   The engine nacelles were fashioned from U-shaped aluminium stringers and covered with aluminium panels held in place by hinges and leather straps. A small cockpit for the flight mechanic was situated between the engines. The nacelles were supported in the wing gap by two inverted V-struts, the ends of which were attached to the lower and upper wing spars. At about one-third of its height the inverted V was joined by a transverse box girder of welded steel to form an elongated A to which the engine bearers, which spanned the entire length of the nacelle, were attached. The bearers consisted of ash planks sandwiched between two layers of heavy plywood. Additional struts ran from the lower wing spars to the ends of the engine bearers to provide extra support for the gear-boxes.
   In most instances the propellers were supplied by Garuda. They were built of spruce and ash laminations and then covered with a thin sheathing of plywood. Large blunt spinners were fitted to the propellers of the Aviatik-built R.VI machines.
   Eight (and on some machines ten) cylindrical fuel tank were installed in the central fuselage section, each with a capacity of 245 litres. The tanks were suspended by steel bands attached to the upper fuselage frames, which were, at this section, reinforced by a welded steel tube structure. A gangway between the tanks allowed the crew to inspect them and to pass between. Fuel was pumped to a 155 litre gravity tank by two propeller-driven pumps mounted either on the fuselage decking or at the fuselage sides near the wing root. The streamlined gravity tank was located under the upper wing between the cabane struts. In an emergency the fuel in each main tank could be jettisoned by a quick-emptying valve. A fuel attendant governed the level of the individual fuel tanks so that the trim of the aircraft was not disturbed during flight.
   In form and construction the four-bay wings were almost identical to those on the earlier Staaken R-planes. Both upper and lower wings had equal span and outline, swept-back leading edges and lower wing dihedral. Each wing consisted of three parts, a centre section and two outer panels. The wings were built around two main spars built-up from seven ash (upper wing) and spruce (lower wing) mouldings to form a double-box cross-section. Ash was utilized in the upper wing because of its higher compressive strength, whereas spruce was used in the lower wing for its superior tensile strength and lighter weight. The individual spar mouldings were glued together and reinforced with ash tongue-and-groove joints. The whole spar length was then covered on two sides by a 2•5 mm. layer of glued plywood. Finally, the spars were wrapped in glue-soaked cotton cloth. The outer wing panels were joined to the centre section with steel collars and bolts.
   The wing ribs were fabricated from spruce, and the rib spacing varied throughout the span, the distance between ribs being less where the stress was greatest. False ribs running from leading edge to front spar maintained correct rib profile at the leading edges.
   Steel compression tube were fastened between the spar at all strut attachment points. The wing was internally braced by two sets of cables; one set crossed between adjoining compression tubes; the other ran from the compression tubes to double ribs which were spaced midway between strut attachment points. The wing struts consisted of faired steel tubing, the diameter of which decreased with increasing span. External wing bracing was composed of double cables throughout. The wing were rigged with slight negative stagger and a rather pronounced incidence, which gradually decreased towards the wingtips.
   The unbalanced ailerons were fitted to the top wings only, and they conformed to the outline of the wing. The steel-tube, fabric-covered ailerons were hinged to false spars in the wing and actuated by cables running from bell-cranks down through the lower wing. The Aviatik-built machines (R.52-R.54) had ailerons with extended balancing areas, and the R.30 was equipped with R.XIV pattern ailerons.
   Initially, the single-bay biplane tail assembly was identical to that of the Staaken R.V: however, at a later date a central fin and rudder were added to counter the control losses due to fuselage twisting. The tailplanes, similar in construction to the wing, used spruce ribs and spars and aluminium tubing for the compression members. The tailplanes were flat on top, cambered underneath, and they were set at an unusually large angle of incidence of 6 degrees. Elevators were fitted to both tailplanes. The interplane struts formed the king-post supports for the characteristic Staaken fin and balanced rudder. All tail surfaces, with exception of the tailplanes, were built of aluminium and covered with fabric.
   The steel-tube undercarriage was a simple robust structure considerably shorter than earlier Staaken types. The massive axles were generally equipped with four wheels at each end, although a few R.VI machines had only two wheels of larger diameter at each axle end. Rubber shock cords were employed in most cases, but later aircraft used bundles of coil springs. A short twin-wheel auxiliary undercarriage was mounted on the nose of all R.VI machines, but it was used only on touch-down. Contrary to the earlier Staaken machines, the normal ground attitude of the R.VI was for the machine to rest on its tail skid.
   The fuselage was basically a lattice-girder structure composed of mixed wood and steel tube construction. The two upper longerons were spruce and the lower ash, fabric-wrapped for their entire length. The frames were welded steel tubing, and those in the rear of the fuselage were of rectangular form, while at the centre-section and nose they were reinforced by diagonal tubes, forming a triangular structure. The forward fuselage was encased in plywood and the remainder was covered with fabric.
   The control cabin, inside and out, was quite modern in appearance for those days. The cabin was fully enclosed, with sliding windows that extended back to the leading edge of the wings. Black shades could be drawn across the windows to avoid dazzle. Two pilots sat on each side of the cabin behind two massive automobile-type steering wheels. The engine throttle controls were located between their seats within each reach, and were grouped in such a fashion that they could be manipulated singly or in unison. The all-important master ignition switch was located immediately behind the throttles, protected by a safety cover. The timely short-circuiting of engines and electrical circuits was responsible for saving several R-planes from destruction by fire after crash landing.
   Initially, a standard gimbal-mounted floating compass, built by Ludolph and adapted from airships, was mounted directly in front of the throttle levers. Its weight and unreliable operation led to the development of a large drum-type compass for R-planes. However, this compass did not perform as desired due to the lack of suitable magnetic alloys. Furthermore, its installation presented certain difficulties, particularly if its magnetic field were placed near steel frames, electric circuits and tachometers. The large drum compass was discarded in favour of two small drum compasses mounted outboard of the pilots' seats The final solution was not achieved until the Bamberg repeater compass was installed in the rear of the fuselage. The course could be set with a flexible shaft, while an electric repeater indicated every variation from the set course. The aircraft commander was supplied with a charting compass for use on his navigating table and a bearing compass for taking visual bearings. Astronomical navigation was attempted, but the shortage of personnel precluded greater use of the technique and forced the development of wireless position-fixing techniques.
   Instruments installed in the pilots' cabin included direct-reading and recording altimeters, a variometer for measuring rate of climb, four electric tachometer, a clock, two air-speed indicators (one for each pilot), a thermo-electric engine-temperature indicator with a switch for reading ten stations and a fluid inclinometer. The final piece of equipment for the pilots was the artificial horizon. Earlier R-planes, R.VI included, were fitted with the Anschutz gyro inclinometer or artificial horizon, which could indicate bank and fore-and-aft inclination. However, the gyro used in the Anschutz system was not free of centrifugal effects and required some 10-15 minutes to reach its operating speed, which meant it could not be used during take-off due to the electrical system involved. To correct the first shortcoming, the weight of the gyro was raised to some 40 kg., which made its use almost prohibitive from a weight standpoint. During mid 1917 the Drexler bank-indicator was introduced. It was a lightweight (5 kg.), greatly simplified gyro device that operated on the precession principle. It reached running speed in less than a minute and was powered by a small propeller-driven generator.
   The electrical machine telegraph by which pilots and mechanics communicated was fixed to the roof of the cabin. Twenty or more commands could be transmitted by mean of preset words indicated by light bulb.
   The wireless sending and receiving equipment was located on the port side, behind the pilot. The commander's navigation table was situated in close proximity across the gangway. The wireless equipment was powered by a 2•5 h.p. Bosch petrol-driven generator which supplied 1000 watt . During wireless silence the Bosch generator could provide electricity for heating the flying suits of seven men and charge the batteries which provided electricity for the lighting system. The lighting could be controlled by the pilots to achieve any degree of illumination. Interior lights were covered with blue glass to reduce glare and danger of being spotted. It was customary to install a battery of six landing light under the fuselage. In addition, two lamps were installed behind the landing gear to throw its shadow on the ground to provide a means for judging height while landing.
   An observation post was located in the extreme nose, with provisions to mount a machine-gun. It was from this position that the aircraft commander directed the bomb run, and this is where the bomb sight was mounted. The dorsal position was equipped with two flexible machine-guns, and the ventral machine-gun was mounted on a small ramp that could be lowered slightly. Two R.VI machines, possibly several others, were equipped with upper-wing mounted guns in the manner of the Staaken R.IV. They differed by having their undersides faired and instead of sliding panels, folding trap-doors provided some protection from the slipstream when lowered. The official German Equipment Tables for R-planes specified three Lewis machine-guns as the normal armament to be carried by the R.VI. These guns were considered by all the combatants to be a superior weapon in the air, as its extreme lightness made it an ideal free gun.
   The bomb load was carried internally in the central section of the fuselage underneath the fuel tanks. Bomb racks for eighteen 100 kg. bombs in three rows of six each were provided, but the 300 kg. and 1000 kg. bombs had to be carried semi-externally. The bomb load varied according to the distance travelled, i.e. the amount of fuel carried. For short distances a bomb load up to 2000 kg. could be lifted, but for long ranges a load of 1000-1200 kg. was more normal.
   The usual flight duration of the R.VI was about 7 hours, which could be stretched to 10 hours if additional fuel tanks were installed. The machines generally flew non-stop from Doberitz to airfields in the Ghent area, some 740 km., on their delivery flights. The longest operational raids were those flown against Le Havre, when a total distance of 800 km. was covered. The maximum range was 900 km. on 3200 litres of fuel and carrying a bomb load of 750 kg.
   The crew varied according to the mission, but generally the complement was seven men, consisting of the commander/navigator and two pilots (of these three, two were usually commissioned officers), a wireless operator, two flight mechanics and a fuel attendant. For additional protection one or two gunners could be accommodated, but this was the exception rather than the rule.
   The Staaken R.VI formed the backbone of the German R-plane squadrons on the Western Front, and carried the brunt of the attack up to the end of the war, but not without severe losses. Out of the eighteen Staaken R.VI machines built, eleven aircraft (possibly more) are known to have been destroyed in the war. Of the eleven, seven made crash landings (R.26, R.27, R.29, R.32, R.34, R.36, R.38); one was lost due to engine failure at take-off (R.28); two were shot down (R.31, R.37) and one crashed as a result of extreme flight manoeuvres (R.52). The effects of weather and the danger of making an emergency landing at night were the chief threats to the operational R.VI bombers. Only two R.VI were definitely shot down by defence forces; the R.37 by anti-aircraft fire near Betz while returning from a raid on Paris and the R.31 by a 151 Squadron night fighter.
   The R.VI was joined by more powerful Staaken types which began to reach the Front in late 1918. Yet the R.VI remained in operational service until the end of the war, and several machines that survived were used in civil ventures in post-war Germany. An engine nacelle identified by the engine serial numbers as belonging to the R.35 is on view at the Polish Air Museum in Krakow.


Colour Scheme and Markings

   Most of the R.VI aircraft were covered with printed camouflage fabric, the pattern used varied according to the manufacturer. The fuselage fabric of the Staaken-built R.VI machines was painted in a dark colour consisting of an undercoating of colourless acetate dope covered by pigmented dope, coloured blue by a mixture of Prussian blue and ultramarine blue.
   National markings were painted on the wingtips, fuselage and tail in the style authorized at the particular period. The Patee crosses of the first Aviatik-built series were represented by white outlines only.
   Some R.VI had serial numbers painted in large white figures on the rear fuselage sides, a practice fairly common in late 1918.


Notes all individual Staaken R. VI Aircraft

   R.25. Staaken built. Four 260 h.p. Mercedes D.IVa engines. Built late 1916. Accepted 6 June 1917. Sent to Rfa 500 for trials on Eastern Front. On 28 July completed a 6 1/2 hour test flight with combat load. Flown to Cologne on 5 August. Operational with Rfa 501. Executed the successful lone attack on St Pancras Station 17/18 February 1918. Commanded by Lt. Max Borchers.
   R.26. Staaken built. Four 260 h.p. Mercedes D.IVa engines. Accepted 24 July 1917. Operational with Rfa 501. Commanded by Oblt. Fritz Pfeiffer, piloted by Lt. Wilhelm Pier. Crash landed in fog and burnt at Scheldewindeke 9/10 May 1918.
   R.27. Schutte-Lanz built. Four 260 h.p. Mercedes D.IVa engines. Acceptance flights in October 1917. Flown from Doberitz to Rfa 501 on 23 January 1918. Commanded by Hptm. Schoeller on England raids. Crash-landed due to frozen fuel lines in Belgium, 7/8 March 1918. Crew uninjured, engines and instruments salvaged, remains destroyed by enemy gunfire.
   R.28. Schutte-Lanz built. Four 245 h.p. Maybach Mb.IVa engines. Completed late 1917, accepted 12 February 1918. Flew from Zeesen to Cologne on 5 June 1918. Operational with Rfa 500. Commanded by Hptm. Schoeller. Crashed 15/16 September 1918 as a result of engine failure.
   R.29. Schutte-Lanz built. Initially four 260 h.p. Mercedes D.IVa engines. Ready for first flight in February 1918. Four 245 Maybach Mb.IVa engines installed and other modifications made in March-April 1918. Fitted with upper-wing gun position. Accepted on 1 May 1918. Flew to Rfa 501 on 3 May 1918. Crashed into trees while landing in fog at Scheldewindeke 9/l0 May 1918.
   R.30. Staaken built. Four 260 h.p. Mercedes D.IVa engines. Acceptance flights in October 1917. The constant need for higher performance led to the development of several types of turbosuperchargers. The R.30 became the test-bed for a centrifugal supercharger built to the designs of Dipl.-Ing. W. G. Noack by Brown-Boveri & Co. of Mannheim. A 120 h.p..Mercedes D.II engine, located behind the starboard pilot, drove the supercharger which provided air to the carburetters via conduits passing internally through the wing and into the nacelles. In September 1918 the R.30 was also equipped with Helix adjustable-pitch propellers designed by Prof. H. J. Reissner. The pitch could be adjusted in flight by means of slotted cams that turned the metal sleeves into which the wooden propeller blades were fitted. The modified R.30 made its first test flight on 23 March 1918 and on 24 April attained an altitude of 19.357 feet, a remarkable improvement over the 12,500 foot ceiling of standard R.VI machines. The maximum speed was raised to 160 km.h., an increase of 30 km.h. over standard machines.
   On 24 May 1918 the R.30 was performing some test for Idflieg over Berlin. Hptm. Krupp and Lt. Offermann were at the controls; Dipl.-Ing Noack and five other crew members were also aboard. At 3300 metres altitude a wrist pin seized, which caused the connecting-rod to break and the piston to burst through the engine housing. This accident was later traced back to improper cooling of the crankcase oil due to modifications required by the supercharged Mercedes engine. A fire started which spread to the lower wing, but by descending rapidly it was possible to blowout these flames. However, long ribbons of fire continued to spew from the nacelle. Noack climbed over the lower wing to the burning nacelle and extinguished the blaze with a portable fire extinguisher. The R.30 landed safely.
   In the early post-war period the R.30 was used for civil work with the name "Fletcher's World" painted on each side of the nose and rear fuselage. .
   R.31. Staaken built. Four 260 h.p. Mercedes D.IVa engine. Accepted January 1918. Operational with Rfa 500. Crashed in flames at Beugny 15/16 September 1918, as a result of enemy action. The British RAF War Diary ha the following statement concerning the loss of the R.31. "Lt. S. C. Broome, 151 Squadron, saw a giant enemy machine held in our searchlights which he attacked firing 500 rounds altogether. The enemy aircraft burst into flames and fell on our side of the lines." Seeing that the aircraft was on fire, the commander. Lt. Wohlgemuht, ran through the aircraft and ordered the crew to bailout. Of the nine, only Lt. Wohlgemuht and one other person were saved by parachute.
   R.32. Staaken built. Four 245 h.p. Maybach Mb.IVa engines. Acceptance flight on 24 January 1918. Delivered to Rfa 501 on 2 April 1918. Crash-landed in fog at Scheldewindeke and was destroyed when its bombs exploded 9/10 May 1918.
   R.33. Aviatik built. Four 260 h.p. Mercedes D.IVa engines. Accepted October 1917. Operational with Rfa 501. Crashed 15 October 1918.
   R.34. Aviatik built. Four 260 h.p. Mercedes D.IVa engines. Completed December 1917. At Altenburg airfield in January 1918 awaiting delivery to Front. Operationa1 with Rfa 501. Crashed near the Front on 21 April 1918, possibly as a result of enemy action. Seven crew killed. Commanded by Oblt. Leistner.
   R.35. Aviatik built. Four 260 h.p. Mercedes D.IVa engine. Acceptance flight on 26 February 1918. Flown to Staaken to be fitted with turbo-supercharger. First test flights in June-July 1918. Weight increased to 9300 kg. empty and 12,875 kg. loaded. Further details are lacking.
   R.36. Albatros built. Four 260 h.p. Mercedes D.IVa engines. R.36 "several weeks away from completion" on 9 July 1917. Accepted in October 1917. Operational with Rfa 501 and believed dismantled after emergency landing on 7/8 March 1918.
   R.37. Albatros built. Initially four 260 h.p. Mercedes D.IVa engines. Acceptance flight on 3 February 1918. In March 1918 radio-telephone experiment were conducted between a ground station and the R.37. Clear transmission of words, numbers and music was attained over a distance of 30 km. using a 500 watt transmission tube. R.37 trailed a 100 metre antenna. In April 1918 Schutte-Lanz installed four 245 h.p. Maybach Mb.IVa engines. Flew to Rfa 500 on 28 May 1918. Forced to land near Betz after hit by French anti-aircraft fire 1/2 June 1918. R.37 was returning from raid on Paris in company with another R-plane. Burned but not fully destroyed by crew, who escaped (later captured ?). Subject to widespread attention by Allied Press at the first R-plane to be inspected by the Allies.
   R.38. Albatros built. Four 260 h.p. Mercedes D.IVa engines. Accepted 27 March 1918. After losing course over Ruhr on delivery flight from Doberitz to Cologne to join Rfa 500, it crashed on an attempted emergency landing at Heisingen on 6 May 1918.
   R.39. Staaken built. Four 245 h.p. Maybach Mb.IVa engines. Completed 18 July 1917. Accepted 9 August 1917. Operational with Rfa 501. Crew consisted of Hptm. von Bentivegni commander and squadron leader; Lt. Frhr. von Lenz, first pilot, Lt. Buth, second pilot; Unteroffiziere Matern and Walter, engine mechanics; Klickermann, wireless operator; W. Teichert, machine-gunner and a fuel attendant (name Jacking).
   The greatest total bombs carried by any R-plane during its operational career is unknown, but the R.39 was probably champion, having dropped a total of 26,000 kg. in twenty bombing raids as painted on the nose of the machine after the war. (For some reason this list did not tally with official records. The raid of 22/23 December 1917, during which the R.39 bombed the Thames estuary, is not included, possibly because it was not a success. According to available records, the R.39 bombed Dunkirk (the alternate target) instead of Dover (the intended target) on 9 May 1918.)
   28 or 29 September 1917 Sheerness 26 May 1918 Abbeville
   6 December 1917 Margate 28 May 1918 Abbeville
   25 December 1917 Boulogne 31 May 1918 Etaples
   28 or 29 January 1918 London 30 June 1918 Amiens
   16 February 1918 London 11 July 1918 Doullens
   7 March 1918 London 13 July 1918 Arras
   1 April 1918 Boulogne 15 July 1918 Rouen
   21 April 1918 St. Omer 16 August 1918 Rouen
   9 May 1918 Dover 24 August 1918 Gravelines
   19 May 1918 Chelmsford 22 (?) 1918 Poperinghe
   The only three 1000 kg. bombs dropped on England were carried by the R.39.
   R.52. Aviatik built. Initially four 300 h.p. Basse & Selve BuS.IVa engines. Completed May 1918. Ground tests on 7 May 1918 showed Basse & Selve engines not fully reliable. Four 245 Maybach Mb.IVa engines were installed. Acceptance flight on 5 June 1918. Delivered to Rfa 500 on 20 June 1918 with acceptance guaranteed on 28 June provided certain defects were corrected. At least one, but possibly all, of the second Aviatik-built R.VI series had modified fuselages. The cockpit was raised, moved farther to the rear and remained open. The front gun position was raised to the level of the upper longerons. Operational with Rfa 500. Crashed and burned on 11/12 August 1918 at Villers la Tour. Hptm. Erich Schilling and four members of the crew perished in the crash.
   R.53. Aviatik built. Four 245 h.p. Maybach Mb.IVa engines. Completed July 1918. Assigned to Rea Cologne as trainer, owing to insufficient performance, September 1918.
   R.54. Aviatik built. Four 245 h.p. Maybach Mb.IVa engines. Expected delivery in October 1918 pending decision whether to install a fifth Maybach engine in the nose. Probably never completed and scrapped in 1919.


SPECIFICATIONS

Type: Staaken R.VI Staaken R.VI Staaken R.VI 30/16
   Manufacturer: Flugzeugwerft G.m.b.H., Staaken, Berlin
   Engines: Four 260 h.p. Mercedes D.IVa engines Four 245 h.p. Maybach Mb.IVa engines Four 260 h.p. Mercedes D.YIa engines
   - - One 120 h.p. Mercedes D.II to drive Brown-Boveri supercharger
   Dimensions:
   Span, 42•2 m. (138 ft. 5 1/2 in.)
   Chord inner, 4•6 m. (15 ft. 1 in.)
   Chord outer, 3•6 m. (11 ft. 10 in.)
   Gap inner, 4•6 m. (15 ft. 1 in.)
   Gap outer, 3•8 m. (12 ft. 5 1/2 in.)
   Incidence inner, 3 1/2 degrees
   Incidence outer, 2 degrees
   Dihedral upper, none
   Dihedral lower, 1 1/2 degrees
   Back stagger, 0-4 m. (l ft. 3 1/2 in.)
   Length, 22•1 m. (72 ft. 6 in.)
   Height, 6•3 m. (20 ft. 8 in.)
   Tail span, 9•0 m. (29 ft. 6 in.)
   gap, 2•0 m. (6 ft. 6t in.)
   Propeller centres, 8•0 m. (26 ft. 3 in.)
   Tractor propellers diameter, 4•26 m. (14 ft.)
   Pusher propeller diameter, 4•3 m. (14 ft. 1 in.)
   Wheel diameter, 1•02 m. (3 ft. 4 in.)
   Areas: Wings, 332 sq. m. (3572 sq. ft.)
   Weights:
   Wings, 2,050 kg.
   Fuselage, 1,450 kg.
   Tail unit, 400 kg.
   Undercarriage, 800 kg.
   Accessories, 250 kg.
   Engines and transmission, 2,730 kg.
   ----
   Empty, 7,680 kg. (16,934 lb.) 7921 kg. (17,465 lb.) 8600 kg. (18,963 lb.)
   Fuel, 1,980 kg. (4,366 lb.)
   Disposable load, 1,800 kg. (3,969 lb.)
   ----
   Loaded, 11,460 kg. (25,269 lb.) 11,848 kg. (26,125 lb.) 11,590 kg. (25,556 lb.)
   Wing Loading: 34•5 kg./sq. m. (7'1 lb./sq. ft.) 35•7 kg./sq. m. (7,3 lb./sq. ft.) 35•0 kg. sq. m. (7,2 lb./sq. ft.)
   Performance:
   Maximum speed, 130 km.h. (80'8 m.p.h.) 135 km.h. (83'9 m.p.h.) 160 km.h. (99-4 m.p.h.)
   Climb,
   1000 m. (3281 ft.) in 11 mins. in 10 mins. in 10 mins.
   2000 m. (6562 ft.) in 27 mins. in 23 mins. in 24 mins.
   3000 m. (9843 ft.) in 55 mins. in 43 mins. in 35 mins.
   Ceiling, 3800 m. (12,467 ft.) in 150 mins. 4320 m. (14,174 ft.) in 146 mins. 5900 m. (19,357 ft.) in 102 mins.
   Duration, 7-8 hrs. 7-10 hrs. -
   Fuel: 2115 litres (465 Imp. Gals.) 3000 litres (660 Imp. Gal.) -
   Armament: Provision for nose, dorsal, ventral and upper-wing machine-gun positions
   Service Use: Western Front with Rfa 500 and Rfa 501, 1917 - November 1918 Western Front with Rfa 500 and Rfa 501, 1917 - November 1918 None

J.Herris Zeppelin-Staaken Aircraft of WW1. Vol 1: VGO.1 - R.IV R.29/16 (A Centennial Perspective on Great War Airplanes 47)

Staaken R.VI
  
  The military situation required more R-planes. Simultaneously, R-plane development coupled with operational experience had resulted in more mature R-plane technology, especially within the Staaken R-plane family. These trends combined with the development of the R.VI to enable mass production of the type, which was the only R-plane design mature enough to justify mass production at the time.
  The Staaken R.VI retained the basic airframe of its predecessor, the R.V, and again was distinguished by a different engine arrangement. The R.VI was also distinguished by being built in quantity instead of remaining a single aircraft; this made the R.VI the largest aircraft type to be placed in mass production during WWI. Excluding the seaplane versions, 18 R.VI aircraft were produced during the war, 12 of them under license by other manufacturers.
  The most visible difference between the R.VI and the Staaken R-planes that came before it was the elimination of the nose engine or engines and associated propeller and engine nacelles with both pusher and tractor engines and propellers. This change had been dictated by operational experience. The nose-mounted propeller required a tall nose landing gear, and that increased the chances of nosing over during hard landings or on rough fields. Moreover, after the crash of VGO.III, a nose engine was thought to increase the likelihood of fire during a mishap due to the proximity of the nose engine to the fuel tanks in the fuselage. Elimination of the nose propeller allowed a shorter nose landing gear that was safer during landing. The shorter nose landing gear enabled a shorter, more robust main landing gear to be used. However, its normal ground attitude of the R.VI was to rest on its tail skid.
  The use of both pusher and tractor propellers in the same engine nacelle was driven by the need to eliminate the cost, weight, and complexity (and its associated reliability issues) of the earlier power transmission systems of gearboxes and clutches. Reducing cost, weight, and complexity were necessary to make the improvements required to enable effective mass production. Moreover, maintaining the complex drive system during operation required highly-skilled flight crews, and this became more of a problem as engines of higher power were installed. Eliminating the complex power transmission systems alleviated these issues and drove the design team to choose the simplest power transmission system possible. The disadvantage was that the fixed-pitch propellers available could not be feathered to reduce the drag of a wind-milling propeller in case of engine failure. This was the problem that had driven most R-plane design teams to create centralized power systems that enabled the flight mechanic to de-couple failed engines from the propellers, but engine reliability had also improved.
  For the engine nacelles, the R.VI design abandoned the wood semi-monocoque structure of the R.V that, despite its advantages, was costly to produce, especially in skilled labor. The R.VI engine nacelles were made of aluminum stringers covered by aluminum panels; the resulting structure was light and strong.
  R.25, the first R.VI, was probably completed it late 1916 and was extensively test-flown before delivery to the air service on June 8, 1917. R.26 was delivered on July 20, 1917, very quickly after the delivery of R.25. The success of the R. VI during the evaluations flights enabled license-production contracts to Aviatik, Schutte-Lanz, and OAW (Ostdeutsche Albatroswerke).
  Needing a lot of reliable power, the R.VI had four 260 hp Mercedes D.IVa engines. These newly-available engines were the most powerful, reliable engines available at the time. In addition to the Mercedes, the R.VI could also be powered by four 245 hp Maybach Mb.IVa engines. The Maybach Mb.IV was one of the first over-compressed production engines; it was designed to give its full power at 2,000 m altitude by increasing its compression ratio. Below 2,000 m the Maybach could not be run at full power due to detonation (premature ignition) that would quickly damage the engine. To produce 245 hp at 2,000 m a regular engine would need to be able to produce 300 hp at sea level. The Maybach was slightly less powerful than the Mercedes at low altitude but produced more power at higher altitudes where the missions were flown.
  Although mounted separately and driving separate propellers, each engine was still geared down to produce lower propeller RPM, so the complex drive system used in prior designs was not completely eliminated. However, the new gearboxes were smaller and lighter than before. The engines and gearboxes were separated by a leather-metal coupling to reduce vibration and accommodate any misalignment. The propeller shaft of the rear engines was longer than those on the front engines to give the rear propellers enough clearance from the trailing edges of the wings. To provide cooling for the gearbox oil, each had a small radiator that extended into the slip-stream. Most propellers were made by Garuda; these were of spruce and ash laminations covered by a thin covering of plywood. Aviatik-built R.VI aircraft had propeller spinners.
  Each engine had its own radiator mounted on the nacelle struts, with the radiators for the rear engines mounted higher than those for the front engines. The engines had self-starters because swinging the propellers by hand was not practical.
  Fuel tanks were built into the fuselage. There were eight or ten of these, of 245 liters each. The tanks were suspended by steel bands from the upper fuselage structure, which was reinforced by welded steel tubes at this location to support the weight. A gangway enabled the crew to move along the fuselage and inspect the fuel tanks. Two propeller-driven fuel pumps mounted on either side of the fuselage decking near the wing roots pumped fuel into a 155 liter gravity tank located under the upper wing between the cabane struts. A quick-emptying valve on each main fuel tank enabled fuel to be jettisoned in an emergency. A crewman was assigned to maintain the fuel levels essentially equal in all main fuel tanks to preserve the aircraft's balance.
  R.VI aircraft had ailerons on the upper wings only and normally were unbalanced. The Aviatik-built R.VI aircraft had ailerons with extended balance areas and the R.30 used ailerons of the R.XIV type. Initially the tail assembly did not have a central fin and rudder, but later this was added to improve control and stability.
  Elimination of the engine and propeller in the nose enabled a flexible machine gun to be fitted there. The aircraft commander could also use the nose position to guide the aircraft during bombing runs. Other gun positions were fitted to the dorsal (two guns) and ventral positions like earlier types and some R.VI aircraft had the upper wing positions over the engine nacelles like the R.IV. However, folding panels replaced the sliding panels to fair the wing surfaces of the R.IV. The official equipment table for R-planes specified three Lewis guns as the normal armament for the R.VI; the captured Lewis guns were lighter than comparable German guns.
  The central bomb bay was configured to carry 18 100 kg bombs in three rows, and 300 kg and 1,000 kg bombs could also be carried. However, the larger bombs protruded outside the aircraft. The typical bomb load was 1,000-1,200 kg, although a bomb load of 2,000 kg was possible if a reduced fuel load was carried. Typical flight duration was 7 hours; additional fuel tanks could be installed to stretch that to 10 hours. The longest missions were 800 km and the maximum operational range was 900 km with a reduced bomb load of 750 kg.
  The typical crew was seven men; a commander/navigator, two pilots, a radioman (then called a wireless operator), two flight mechanics, and a fuel attendant (today the nomenclature for these last three would be flight engineer). Additional gunners could be carried if thought necessary but this was rare.
  The R.VI was used from its introduction to the end of the war. Many were destroyed in operational accidents; 7 of the 18 built were destroyed in crash-landings, one was lost due to engine failure during take-off, and one was lost due to extreme flight maneuvers the airframe was not designed for. Aviation technology, procedures, and navigational aids were early in their development and the larger R-planes were as susceptible to these dangers as smaller aircraft.
  Only two R-planes were shot down in combat. In both cases, the aircraft were being used for short-range missions just behind the lines, making them easier for the defending night fighters to find. These missions were undertaken late in the war when the longer-range missions the R-planes were designed for were abandoned for tactical missions due to the increasingly desperate situation on the ground. No R-plane was shot down during the long-range night bombing missions the R-planes were designed to perform.


Staaken R.VI Details (Table 1 of 4)
Serial Manufacturer Engines Rudders Propellers Exhaust
R25 Staaken Mercedes 2 Two-bladed Garuda All in engine to one large exhaust header
R26 Staaken Mercedes 2 Four-bladed Garuda All in engine to one narrow Pipe
R27 Schutte-Lanz Mercedes 2 Two-bladed Garuda 6 narrow pipes in engine
R28 Schutte-Lanz Maybach 2, then 3 Two-bladed Garuda, small spinners 6 into one pipe
R29 Schutte-Lanz Maybach 3
R30 Staaken Mercedes 2, then 3 Two-bladed Garuda, small spinners 6 narrow pipes in engine
R31 Staaken Mercedes Two-bladed
R32 Staaken Maybach 2, then 3 Four-bladed Schwartz, small spinners 6 narrow pipes in engine
R33 Aviatik Mercedes 2 Two-bladed Garuda, spinners All in engine to one large exhaust header
R34 Aviatik Mercedes 2 Two-bladed Garuda, spinners All in engine to one large exhaust header
R35 Aviatik Mercedes
R36 OAW Mercedes Two-bladed Garuda, spinners 6 narrow pipes in engine
R37 OAW Maybach 3 Two-bladed
R38 OAW Mercedes 3
R39 Staaken Maybach 2 Two-bladed 6 into one
R52 Aviatik Maybach Two-bladed, spinners 6 into one
R53 Aviatik Maybach
R54 Aviatik Maybach
Mercedes = 260 hp Mercedes D.IVa; Maybach= 245 hp Maybach Mb.IVa

Staaken R.VI Details (Table 2 of 4)
Serial Nacelle Struts Special Features
R25 All wide
R26 Top and bottom outside thin, bottom inside wide
R27 All thin
R28 Top and bottom outside thin, bottom inside wide Upper wing guns
R29 Upper wing guns
R30 Top and bottom outside thin, bottom inside wide Upper wing guns, Supercharger
R31
R32 Top and bottom outside thin, bottom inside wide
R33 Top and bottom outside thin, bottom inside wide White outlined Eisern crosses only. White "Der Laurige Hund" badge on nose
R34 Top and bottom outside thin, bottom inside wide
R35 Supercharger?
R36 Top and bottom outside thin, bottom inside wide
R37
R38
R39 Top and bottom outside thin, bottom inside wide
R52
R53
R54


Staaken R.VI Details (Table 3 of 4)
Serial Paint Paint & Construction Changes
R25 Hand painted, four colors, darken from top and bottom by dark blue paint(?) Extra wireless dynamo mounted on the LH front centre-section strut
R26 Hand painted, four colors, darken from top and bottom by dark blue paint(?) Different propellers, two 300 kg bomb carriers
R27 Hand painted, four colors, darken from top by transparent black paint, bottom wings without Extra wireless dynamo mounted on the RH front centre-section strut
R28 Hand painted, four colors, darken from top by transparent black paint, bottom wings without
R29
R30 All canvas printed five colors, night pattern lozenge Extra windows on the fuselage sides, Helix controllable pitch propellers
R31 Extra window on the front of the roof, two 300 kg bomb carriers
R32 Hand painted, four colors, darken from top and bottom by dark blue paint(?)
R33 Hand painted, four colors, darken from top by transparent blue paint, bottom wings without Extra wireless dynamo mounted on the RH front centre-section strut, front headers tube dismounted, extra windows
R34 Hand painted, four colors, darken from top and bottom by dark blue paint(?) Extra window on the front of the roof
R35
R36 All canvas printed five colors, night pattern lozenge Balanced ailerons, extra windows on the fuselage sides
R37 Hand painted, four colors, darken from top by transparent blue paint, bottom wings without Extra windows on the fuselage sides, two 300 kg bomb carriers
R38
R39 Hand painted, four colors, darken from top and bottom by black paint)?) Extra wireless dynamo mounted between the centre-section struts, two 300 kg bomb carriers
R52 All canvas printed five colors, night pattern lozenge "Glass house" cabin, new BuS.IVa engines, extra balanced ailerons
R53 All canvas printed five colors, night pattern lozenge
R54 All canvas printed five colors, night pattern lozenge

Staaken R.VI Details (Table 4 of 4)
Serial Lost Fate
R25 ? ?
R26 9/10 May 1918 Crash landed in fog and burnt at Scheldewindecke
R27 7/8 March 1918 Crash landed due to frozen fuel lines in Belgium, destroyed by enemy artillery after that
R28 1918 Crashed on take off, due to engine failure
R29 9/10 May 1918 Crashed into trees while landing in fog at Scheldewindeke
R30 - Survived the war
R31 15/16 Sept.1918 Crashed in flames at Beugny, possibly due to enemy fire
R32 9/10 May 1918 Crash landed in fog at Scheldewindeke and was destroyed by the bombs exploding ...
R33 ?
R34 20/21 April 1918 Crashed after possible enemy action,remains with one air mechanic body discouverd by Mr. Piet Steen at Poelkapelle mud field.
R35 ? Probably fitted with a supercharger March 1918
R36 7/8 March 1918 Dismanteld after a crash landing
R37 1/2 June 1918 Forced landing near Betz (France) after hits from French AA- fire, burned
R38 6-May-18 Crashed on a ferry flight near Heisingen (Germany) after loosing orientation
R39 - Survived the war, possibly the most successful R-plane, dropping 26,000 Kg of bombs in 20 raids
R52 11/12 Aug. 1918 RFA 500, Crashed and burnt at Villers la Tour (France)
R53 - Discovered in 1919 by ICCIA at Staaken/Doberitz, Helle 12
R54 -



Staaken Specifications
Type R.VI R.VI R.VI 30/16
Engines 4x260 Hp Mercedes D.IVa 4x245 Hp Maybach Mb.IVa 2x160 Hp Mercedes D.III 4x220 Hp Benz Bz.IV
Span 42.2 m (138'5 1/2") 42.2 m (138' 5 1/2") 42.2 m (138'5 1/2")
Chord (inner) 4.6 m (138' 5 1/2") 4.6 m (138'5 1/2") 4.6 m (138' 5 1/2")
Chord (outer) 3.6 m (11' 10") 3.6 m (11' 10") 3.6 m (11' 10")
Length 22.1 m (72' 6") 22.1 m (72'6") 22.1 m(72'6")
Height 6.3 m (20' 8") 6.3 m (20' 8") 6.3 m (20' 8")
Tail span 9.0 m (29' 6") 9.0 m (29' 6") 9.0 m (29' 6")
Wing Area 332 m2 (3,572 ft2) 332 m2 (3,572 ft2) 332 m2 (3,572 ft2)
Wt. Empty 7,680 kg (16,934 lb.) 7,921 kg (17,465 lb.) 8,772 kg (19,342 lb.)
Wt. Fuel 1,980 kg (4,366 lb.) - 2,140 kg (4,719 lb.)
Wt. Payload 1,800 kg (3,969 lb.) - 2,123 kg (4,681 lb.)
Wt. Loaded 11,460 kg (25,269 lb.) 11,848 kg (26,125 lb.) 13,035 kg (28,742 lb.)
Max Speed 130 km/h (80.8 mph) 135 km/h (83.9 mph) 160 km/h (99.4 mph)
Climb 1,000 m 11 minutes 10 minutes 10 minutes
Climb 2,000 m 27 minutes 23 minutes 24 minutes
Climb 3,000 m 55 minutes 43 minutes 35 minutes
Ceiling 3,800 m 4,320 m 5,900 m (in 102 minutes)
Duration 7-8 hours 7-10 hours -

M.Dusing German Aviation Industry in WWI. Volume 2 (A Centennial Perspective on Great War Airplanes 85)

Luftfahrzeugbau Schutte-Lanz, Zeesen (SchuI)

Aircraft Development:

<...>
  As the military need for R-airplanes grew, the Inspectorate of the Air Force also approached Schutte-Lanz with the desire to produce R-airplanes based on the Staaken model. The enormous dimensions of these aircraft meant that special hangars had to be erected to avoid the parallel production of airships and airplanes in the airship hangar.
  The good flight performance of the in-house developments convinced the military administration to such an extent that, among other things, D- and also R-airplanes were built in series for the front.
<...>

Журнал Flight

Flight, November 28, 1918.

NOTES ON GERMAN BOMBERS
THE FOUR-ENGINED GIANT
[Issued by Technical Department (Aircraft Production), Ministry of Munitions.]
(Continued from page 1322.)

   THERE are known to be a number of different types of giant bomb-carrying aeroplanes, distinguished by the four, five, or six engines with which they are fitted.
   Examples of four-engined and five-engined aeroplanes have been brought down, but unfortunately, in all cases, in such a damaged condition that complete reconstruction is impossible.
   The following particulars relate to a four-engined machine which landed near Betz on the night of June 1st.
   It was almost completely burnt by its occupants, and the metal parts alone remain, together with a few fragments of the body work.
   The general arrangement of this aeroplane, together with the principal dimensions, is given in the accompanying drawings (Figs. 42, 43, 44 and 45).
   In contradistinction to the two-engined machine, there is considerably more steel in the construction, and this material is used in place of wood for the rear portion of the fuselage.
   The principal point of interest is the mounting of the four engines, all of which are of the 260 h.p. Maybach type, six cylinders in a line; the horse-power has been forced up to 300, giving 1,200 h.p. in all. They are placed end to end, as shown in Fig. 46, and each drives a separate screw.
   In order to bring the centre of gravity of the machine sufficiently far forward, the weight of the two engines is massed towards the leading edge of the main plane; by driving the screws through shafts and reduction gears, the necessity of cutting away large sections from the planes to give room for the rear propellers has been avoided.
   The arrangement of the engine unit on each side of the fuselage is diagrammatically shown in Fig. 46, from which it will be seen that the two engines are placed close together, and that the rear motor is some little distance away from its screw. The forward engine is, however, mounted close up to the tractor screw.
   The employment of shafts and reduction gears necessitates fly wheels on the engines. These are 4 metre in diameter, and made of cast iron. The tubular driving shafts between the fly wheel and the gear box are furnished with flexible leather couplings. These are of a novel type, and consist of a male and female drum, each furnished with circumferential notches, between which are interposed a series of flat leather strips. The female drum forms part of the fly wheel.
   The gear box consists of a casing of aluminium, provided with cooling fins, which may be seen in Figs. 47 and 48.
   Beneath each gear case is a small radiator for cooling the lubricating oil circulated through the engine. This radiator can be seen in Fig. 47, and consists apparently of a flat semicircular tank, fitted with numerous transverse tubes of fairly large diameter (about 20 mm.) in a manner similar to that of a honeycomb radiator. A pump mounted at the base of the radiator is also furnished with an electrical thermometer, giving a reading on a dial in the cockpit.
   Each engine is fitted with a self-starting arrangement of the type usually fitted to Maybach motors. The exhaust pipe may be closed by means of a shutter, and all the cylinders can be filled with gas from the carburettor by means of a large hand-pump, for which purpose all the valves are held open. When these valves are closed, and the starting magneto operated, the engine fires and continues running. Each engine has its own radiator (Fig. 49), which is mounted directly above it, and supported by struts and stay wires at a point about half-way between the top and bottom planes. These radiators are of the type usually fitted to D.F.W. machines. They are rectangular in shape, with their greater length placed horizontally, and the radiating surface consists of a series of zig-zag tubes placed vertically.
   The engine bearers consist of stout ash spars, reinforced with multi-ply wood. Owing to the burnt condition of the machine no information could be obtained as to the engine controls and the screws were also too badly damaged to yield definite information as to dimension and construction, though they appear to be made chiefly of ash and covered with a thin veneer.

Wing Construction.
   The spars are shown in Fig. 50, built up very elaborately in sections, and consisting of no less than seven sections of spruce, reinforced with multi-ply on each side, and finally carefully bound with doped fabric.
   The spars of the lower wings are continuous, that is to say, they run right across the centre section of the fuselage, to the longerons of which they are secured, contrary to the usual practice, in which special compression members, forming part of the fuselage construction, are employed. The wing surface, both upper and lower, is divided into three sections of which the middle section extends to the engine mountings on each side. The spars in this section are both at right angles to the axis of the fuselage. At each side of the middle section the leading edge of the wings is boldly swept back as well as tapered. The rear spars of the wings, together with those of the centre section, form a straight line from wing-tip to wing-tip, but the front spars are swept back.
   The ribs, of which a detail drawing is given in Fig. 51, are built up, and of girder form.
   Between the leading edge and the leading spar, numerous extra ribs occur in addition to the main ribs. Internal bracing against drag takes the form of steel tubular compression members and steel cables, the former being placed at a point coincident with the attachment of each interplane strut. An additional bracing is installed, of which the compression member consists of a double rib placed half-way between the struts. In each case the bracing wires pass obliquely right through the spars.
   The ribs are mounted parallel to the line of flight.
   The disposal of the spars is as follows :-

Top Plane. -
   Leading edge to centre of leading spar 1 ft. 9 1/2 ins.
   Distance between centres of spars 5 ft. 7 1/2 in.
   Trailing edge to centre of rear main spar 5 ft.
Bottom Plane.-
   Leading edge to centre of leading spar 1 ft. 7 1/2 ins.
   Distances between centres of main spars 5 ft. 1 in.
   Trailing edge to centre of rear main spar 5 ft. (approx.)

   The trailing edge of this aeroplane was too badly damaged to permit of this measurement being given accurately.
   Between the interplane struts the rear spars are thinned down in width, but their depth remains practically constant from root to tip. Such tapering as exists is so arranged as to promote a decided wash-out of the angle of incidence near the tip. This is done by tapering the front spar on its upper edge, and the rear spar on its lower edge.

Ailerons
   These are on the top planes only, and are provided with a framework of steel tubing. They are not balanced, and the controls are led in the usual manner through the bottom plane from the aileron lever.
   The span of each aileron is 22 ft. 5 ins., and the chord 3 f t . 4 ins.

Inter-plane Struts
   These are of large-diameter steel tube, covered in with a streamline fairing consisting of three-ply mounted on a light rib-work of wood.

Bracing
   The attachment of the bracing cables to the spars is somewhat similar to the bracing of the Fokker fuselage; that is to say, the wires, instead of being anchored at each end to an eyebolt, are double, and are looped round the spar, to which is fixed a grooved channel-piece for the reception of the cable. It is difficult to see that any advantage is gained by this arrangement.

Tail Unit
   A biplane tail, somewhat similar to that of the Handley-Page, is fitted. The fixed tail planes, the angle of incidence of which can be adjusted through small limits, are of wooden construction, and have the following dimensions :-

Span each side of fuselage 12 ft. 4 ins.
Chord (average) 4 ft. 10 ins.
Gap 6 ft. 9 1/2 ins.

Elevators
   These are fitted to both the top and bottom tail planes, and are of aluminium construction, the ribs, being of girder form, somewhat similar in construction to the ribs of the main planes. The elevators are not balanced ; the top and bottom elevators are fitted with independent control levers, but are presumably operated together from the control stick. Their dimensions are as follows :-

Span 28 ft. 6 ins.
Chord at tip 2 ft. 4 ins.
Chord at centre 1 ft. 6 ins.

Fins
   There are three fins; two outer ones forming interplane struts, and an inner central one of triangular shape.

Rudders
   The framework of these organs is built up of aluminium in the manner set forth in detail in Fig. 52. This also shows the quadrant at the foot of the rudder posts by means of which they are operated; each rudder post is fitted with ball bearings, both top and bottom.

Undercarriage
   Beneath each engine section is an undercarriage consisting of a massive axle fitted with four wheels at each end. This isle is attached by india-rubber shock absorbers to the tubular steel V-struts which form extensions of the engine bearer struts. A third undercarriage is mounted under the forward part of the fuselage, and consists of an axle with one pair of wheels.

Armament
   Only two gun mountings were found in the wreckage; they were fitted to a revolving turret in the gunner's cockpit. The mountings are of the fork type, and are situated on opposite sides of the circle. No arrangements for firing under the tail were found, nor was there evidence of a forward gun mounting.

Bomb Gear
   Two steel tubular frameworks are fitted, one on either side of the fuselage. They are apparently adapted to carry very large bombs, probably of 1,000 kg. each, The release gear appears to be similar to that used on the Friedrichshafen , and already reported upon.


Flight, September 11, 1919.

AVIATIK "MILESTONES"

The Aviatik, Type R (Riesenflugzeug)
   was a four-engined machine, following more on the lines of the Staaken type. It was built towards the end of 1918, and was fitted with four Benz engines, the two front ones being of the 200 h.p. six-cylindered type, and the two pushers of the 500 h.p. twelve-cylindered Vee type, fitted with reduction gearing. As will be seen from the photograph, this machine was of very large dimensions, with its engines placed end to end in nacelles between the planes. It had a biplane tail.