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Dornier Do S
commercial flying boat
The little sister of the Do X
On Lake Constance, testing of the twelve-engine
Dornier Do X airship was just coming to an end when the Do S took off on its maiden flight in the autumn of 1930. The
four-engine flying boat for 30 passengers was actually nothing more than a scaled-down Do X. Peter Pletschacher reports on this almost forgotten one-off, which never went into series production due to a lack of interest in buying.The success of the twin-engine whale and the four-engine super whale in the 1920s was the reason for Dornier toto apply the experience gained in the meantime with the Do X to a new commercial flying boat. The Do S shoulda modern, larger successor to the Wale, and at the 12th Aero-salon Paris, Dornier hoped to attract its first customers.to find. Just a few weeks after its maiden flight on 23 September 1930, the Do S flew along the Rhine toAmsterdam and further along the course of the Meuse then to Paris, where it watered on the Seine. After dismantling the outer wings, the flying boat was converted into aAerosalon, which at that time still took place in the Grand Palais in the middle of the city. After the exhibition, theDo S from the Seine to demonstration flights and received a lot of attention.But the hopes were premature, neither Lufthansa nor other customers could decide to buy,so that the construction of two more units, which had already begun, had to be stopped. To this failurethe global economic crisis at the time, which also had a significant impact on the aviation industry. Theprototype of the Do S was finally taken over by the Reich Ministry of Aviation in 1933 and the German Commercial Pilot School (DVS) in List on Sylt. A few years later, the flying boat made its way to theOstsee Bruch and had to be written off. Even the external appearance of the Do S showed the closeRelationship with the Do X: The spatial separation of the crew from the passengers is particularly striking. Thefour-man crew was accommodated in an upper deck, which was connected via a ladder from themain deck. Behind the driver's cab with double steering were the workstations of the navigator, theMachinists and the radio operator. From the machinist's room, the four Hispano-Suiza engines, each with 600 hp, wereand through a lockable hatch in the top of the wing and ladders, the engines were also protected during thecan be reached in a hurry. The four-blade Dornier wood propellers were two-part, and the two twin engine nacelleswith tension and pressure screws were connected to an "upper wing" that was about a third of the span of themain wing. To reduce the risk of fire, the tanks with a total capacity of3500
liters are not housed in the fuselage or in the wings, but in the fin stubs.These floats, which are typical of almost all Dornier flying boats and mounted on the side of the hull, guaranteedin contrast to the support floats mounted on the undersides of the outer wings, which are otherwise common in flying boatsa particularly soft and steady increase in stability when leaning on the water and an excellentDamping of rolling movements. Together with the flat, longitudinally and transversely stepped bottom of the boat and thetypical keel box behind the step, a trademark of the Dornier flying boats, which are known for their excellent sea-goingproperties had become famous.It is not without reason that these fin stumps were also called "underwings". Because Dornier had in the early thirtiesyears ago to carry out a patent dispute with the company Rohrbach, which in the Do X and Do S of an infringement of its patenton the design as a monoplane shoulder-wing aircraft with engines above the supporting structure. In the course of thisHowever, Dornier was able to prove that the boat stubs contribute to the overall buoyancy and thereforeboth types of flying boats were not to be classified as single-deckers, but as single-and-a-half-deckers. The court followed thisargument, so that this legal dispute was decided in favor of Dornier.On the main deck, the collision and anchor room were located at the front behind the bow, behind which was a cabin for 12passengers and the boarding room, followed by the toilet, a library cabinet and the on-board pharmacy, andbehind it another cabin for 10 passengers. With correspondingly reduced comfort, however, instead of 22a total of 30 passengers will be transported.The construction method followed the principles proven at Dornier. Highly stressed parts such as fittings or even theTail spars were made of steel, otherwise duralumin was used for all load-bearing parts. The hullconsisted of a smooth sheet metal construction, which was stiffened on the inside by frames and on the outside by longitudinal profiles. WithWith the exception of the area under the engines, the entire wing was fabric-covered for weight reasons. TheAilerons and elevators were relieved similar to the Do X - by auxiliary rudders (they were called "garden benches"), whichHeight fin was adjustable. Two rudders on the vertical stabilizer were used for trimming in the event of a one-sided engine failure.The unsuccessful Do S was completely overshadowed by her big, famous sister Do X and was soon forgotten. TheWal, on the other hand, who was actually supposed to be replaced by the Do S, remained with constant further developments until well into the thirtiesyears.