G.Haddow, P.Grosz The German Giants (Putnam)
High-powered naval R-seaplanes were mentioned in the German Naval Archives as early as December 1916. At this time a report was filed by Oberleutnant z.S. Mans, who had just returned from an inspection tour to Seemoos, where he examined the Dornier Rs.II. Based on what he saw, Mans doubted that a 1200-2000 h.p. flying-boat could be successfully developed, because it would be unseaworthy and cumbersome. The Mans report stated that a 2000 h.p. seaplane would require at least a 60 metre wingspan and would probably have to be a float-plane.
If Dornier heard these opinions he was not influenced by them, for he pursued the subject of higher-powered seaplanes and actually prepared several design proposals. Perhaps Alfred Colsman, the general manager of the Zeppelin concern, provided a clue to the original purpose behind Dornier's proposals. He wrote that during the war serious consideration had been given to sending gold bullion to Afghanistan by airship. Even though it was intended to sacrifice the airship, the overall risk was too great and the airship plan was dropped. At this point, Colsman approached the Navy with a plan to build a four-engined flying-boat to attempt a flight to the Black Sea. Perhaps the 2400 h.p. Dornier flying-boat project came into being as a result of Colsman's scheme.
At any rate, the projected flying-boat (factory drawing 1575 dated 21 March 1918) was very modern in appearance, and the lines of future Dornier flying-boats followed it closely. The hull and fuselage became one again, as in the Rs.I. Four 600 h.p. Maybach engines were mounted in tandem in nacelles that formed an integral part of the wing. The configuration of placing the propeller in front of the leading edge of the wing had been carefully investigated by Schulte-Frohlinde in 1917. Tests which were a continuation of the tandem-engine experiments of 1916 showed that propeller thrust was not adversely influenced provided the propeller was not mounted too close to the leading edge. The typical broad wing was mounted over the fuselage on pylons and braced by struts leading to the sponsons. The armament was composed of machine-guns or cannon located in bow, dorsal and waist gun positions.
An order was placed by the Navy for two aircraft numbered 8803 and 8804 in June 1918 to be powered by four 600 h.p. Maybach engines.
The 600 h.p. Maybach engine was in its first experimental stages at the time the Navy order was placed. Although one model was completed in 1918/19, it was unlikely that production versions could have been delivered prior to the completion of the projected flying-boat. Perhaps the next design (factory drawing 1580 dated 5 April 1918) reflected this possibility. This project was similar in layout, but was powered by eight 245 h.p. Maybach Mb.IVa engines buried in the hull driving wing-mounted tandem propellers. The length of the fuselage was increased to make room for the eight buried engines, while the elimination of the nacelles made it possible to reduce the overall height of the machine.
The Dornier project drawings Nos. 1575 and 1580 are good representations of the flying-boat ordered by the Navy. According to Dornier sources, the designation of these machines was to have been Rs.V.
Dornier himself wrote that a machine with eight engines, much larger than the Rs.IV, had been ordered by the Navy, but could not be completed. Another source has claimed that the 2400 h.p. Dornier R-flying-boats were to have a maximum speed of 190 km.h. and carry machine cannon in addition to machine-gun armament. No information is available to indicate if these projects progressed appreciably beyond the design stage.
Type: Dornier R-Flying-boat Project (Drawing 1575) Dornier R-Flying-boat Project (Drawing 1580)
Manufacturer: Zeppelin-Werke Lindau G.m.b.H., Seemoos, Lake Constance
Engines: Four 600 h.p. Maybach Mb.VI Eight 245 h.p. Maybach Mb.IVa engines
Span, 44 m. (144 ft. 4 in.) Span, 44 m. (144 ft. 4 in.)
Length, 28 m. (91 ft. 10 in.) Length, 30 m. (98 ft. 5 in.)
Height, 6•5 m. (21 ft. 4 in.) Height, 5•7 m. (18 ft. 8 in.)
Having proven its ability to design and build large monoplane, the Dornier works was included in the 1917 high-performance, advanced R-plane programme. No doubt a variety of designs were proposed and investigated before the final version was chosen. The Dornier R.I was an all-metal monoplane quite unlike previous Dornier R-plane designs, a very modern aircraft with pleasing lines. Judging from its number, it is believed that the project drawing was prepared in December 1917 or January 1918. The three-spar, cable-braced wing was patterned closely after that of the Dornier Rs.III. Four Maybach engines were located centrally in the fuselage and drove two large propellers through a simple right-angle transmission system. The radiators were mounted close to their respective engines; two on each side of the nose well clear of the fuselage and two over the middle wing spar. A ventral machine-gun was located beneath the trailing edge cut-out of the wing, free of interference from the landing gear. The pilot's cockpit was situated well aft in front of a large turret intended for a 20 mm. cannon. The bombs were carried internally (and possibly also externally) in a bomb-bay underneath and aft of the engines. The streamlined landing gear housing served not only to reduce drag but also as a support structure for the wing bracing cables.
In an internal Idflieg status report for September 1918 we learn that: "The construction of the Dornier R.I has been halted because only Navy aircraft are to be built at Lindau in the future. In addition, the new Staaken project incorporating all the latest experiences, is a further developed succession of the Dornier R.I."
The R.I concept stayed with Dornier for a long time, and the similarity between it and the Do F of 1931 and it followers (Do 11, Do 13, Do 23) is truly remarkable.