Dornier Rs . III The Dornier Rs . III was a large four - engined monoplane flying boat designed by Claudius Dornier and built during 1917 on the German side of Lake Constance at the Zeppelin - Lindau works . Design and development . Although the Rs . III differed in appearance from its predecessors , it was the result of the experience gained from building and flying the Dornier Rs . I and Dornier Rs . II . The broad hull was retained as well as the push - pull tandem nacelles , but the open framework tail boom was replaced by a steel and Duralumin fuselage that sat on the centreline of the high mounted wing and the substantial tubular trusses supporting the wing were replaced by conventional wire bracing . The short and broad hull accommodating the flight crew supported the engine nacelles and the wing centre section on a frame - work of struts , in similar fashion to the later version of the Rs . II . The high set fuselage had several tasks , providing gun positions for defence , ensuring that the tail unit was as high as possible to reduce damage from spray and to act as a king - post for the wings landing - wire bracing . Constructed of steel longerons riveted to Duralumin frames and covered with Duralumin sheet over the forward portion and fabric aft it supported the tail unit which consisted of a biplane tail cellule with elevators and a large central rudder , initially with a long central fin , but later with two smaller fixed fins in the tail cellule . At approximately the mid - wing chord position the fuselage had a cockpit with provision for two machine guns and also housed a sound - proof wireless cabin in the nose . The hull was very similar to that of the Rs . II , being short and broad with a cockpit near the nose protected by a large coaming . Fuel for the engines was housed in a large fuel tank mounted in the hull , which also provided accommodation for the crew when not at their stations . The flight crew usually consisted of two pilots , a commander , and possibly a navigator , with gunners and mechanics to man the guns and engines as well as manually pump fuel up to each engine ' s gravity tanks . Operational history . As the Rs . III neared completion , the facilities at the Norderney Seaplane station on the North Sea coast were also completed . Delivery of the Rs . III was planned to follow the river Rhine after crossing the Black Forest , with a fighter escort between Rottweil and Duisburg due to the proximity of Allied forces , as well as a guide aircraft to prevent it inadvertently crossing the Dutch border . Flight testing of the Rs . III carried on apace from November 1917 , at the Lake Constance factory , with good results . Flying characteristics were generally good , the aircraft proving easy to fly , taxi on water , and capable of taking off in moderate seas . With only minor modifications , the Rs . III was ready for its delivery flight by the end of January 1918 , but the route was covered with fog . The weather cleared by 19 February when the Rs . III set off on its 7 - hour non - stop delivery flight to Norderney . Operational testing at Norderney cleared the giant Rs . III for service with the Imperial German Navy on 13 June 1918 and it was turned over to the SYK on 27 August 1918 for further Navy tests . After the Armistice the Rs . III was not destroyed immediately but continued flying with the German Navy Air Service on mine clearing duties until the Allied Control Commission finally ordered its scrapping in July 1921 . The Rs . III had proved easy to fly ( but with some minor quirks ) , easy to maneuver on the water and durable , due to its metal construction .