The Dornier Do S was a 22-passenger

flying boat A flying boat is a type of seaplane with a hull, allowing it to land on water. It differs from a floatplane in having a fuselage that is purpose-designed for flotation, while floatplanes rely on fuselage-mounted floats for buoyancy. Though ...

airliner flown in

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

in 1930.

Design and development

The all-metal Dornier Do S was intended to replace the Dornier Do R 4 Superwal, a four-engined, 19-passenger flying boat flown four years earlier. Both were

high-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing config ...

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

s but the Do S was bigger (about 7–8%) in both span and weight, and had a significantly improved hull which seated 22 passengers. A large increase in effective wing area, which included

sponson Sponsons are projections extending from the sides of land vehicles, aircraft or watercraft to provide protection, Instantaneous stability, stability, storage locations, mounting points for weapons or other devices, or equipment housing. Watercra ...

s and an auxiliary winglet, decreased the

wing loading In aerodynamics, wing loading is the total weight of an aircraft or flying animal divided by the area of its wing. The stalling speed, takeoff speed and landing speed of an aircraft are partly determined by its wing loading. The faster an airc ...

by about 30% and the landing speed by . The main wing of the Dornier S was in three parts, with a central panel attached to the crew's compartment on top of the main

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

, and two outer panels. It was rectangular in plan, with a chord of , apart from slightly blunted tips. The wing was built around three

duralumin Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of age hardening, age-hardenable aluminium–copper alloys. The term is a combination of ''Düren'' and ''aluminium'' ...

trellis spars, with dural ribs and skin. The inner panel was supported by two vertical struts from the

s. On each side the main outer bracing was provided by a single strut from the inner sponson to the central spar of the outer panel, at about half-span. These were assisted by steel

flying wires In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of struts, which act in ...

from below, between the forward and rear spars and the sponsons, and from above by a single wire from the raised engine mountings and their cross-bracing auxiliary wing, to the forward spar. High

aspect ratio The aspect ratio of a geometry, geometric shape is the ratio of its sizes in different dimensions. For example, the aspect ratio of a rectangle is the ratio of its longer side to its shorter side—the ratio of width to height, when the rectangl ...

aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement aroun ...

s occupied all the

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 1997. ...

of the outer panels, aerodynamically balanced by small auxiliary surfaces mounted forward and well above the hinge line. The lower part of the fuselage followed Dornier's usual practice, with a narrow-V cross-section forward changing to a flat bottom, with a deeper centre region, near the single step and a V-section aft ending with a water rudder. There were two passenger cabins, one seating twelve forward of a lobby accessed by a starboard side door and containing a cloakroom, toilet, library and medicine cabinet. Behind it was a second passenger compartment for ten, with a kitchen aft. At the stern the

empennage The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow.Crane, Dale: ''Dictionary of Aeronautical Terms, third ed ...

was conventional, with a

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. F ...

that had a swept

leading edge The leading edge is the part of the wing that first contacts the air;Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, 1997. alternatively it is the foremost edge of an airfoil sectio ...

and blunted top, carrying a rudder which reached down to the top of the fuselage. Its

tailplane A tailplane, also known as a horizontal stabilizer, is a small lift (force), lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters ...

, with a plan similar to that of the wing, was braced from below by a pair of parallel struts on each side and was adjustable in flight. It carried

elevators An elevator (American English) or lift (English in the Commonwealth of Nations, Commonwealth English) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive tracti ...

which were aerodynamically balanced in the same way as the ailerons. The crew were housed in a separate structure above the cabin which also formed the central connection between wing and fuselage. It began well forward of the

and ended just aft of the trailing edge. The pilot's open

cockpit A cockpit or flight deck is the area, on the front part of an aircraft, spacecraft, or submersible, from which a pilot controls the vehicle. The cockpit of an aircraft contains flight instruments on an instrument panel, and the controls th ...

near the front had a pair of side-by-side seats with dual controls. Further aft, there were positions for a flight engineer, a navigator and a radio operator, one of whom could act as co-pilot. The Do S was powered by four Hispano-Suiza 12Lbr water-cooled

V-12 engine A V12 engine is a twelve-cylinder piston engine where two banks of six cylinders are arranged in a V configuration around a common crankshaft. V12 engines are more common than V10 engines. However, they are less common than V8 engines. The f ...

s, mounted above the wings in

push-pull configuration An aircraft constructed with a push-pull configuration has a combination of forward-mounted Tractor configuration, tractor (pull) Propeller (aircraft), propellers, and backward-mounted (pusher configuration, pusher) propellers. Historical The e ...

pairs and driving four-bladed

propeller A propeller (often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working flu ...

s. Each engine in a pair had a

radiator A radiator is a heat exchanger used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics. A radiator is always a ...

occupying half the front of the rectangular section

nacelle A nacelle ( ) is a streamlined container for aircraft parts such as Aircraft engine, engines, fuel or equipment. When attached entirely outside the airframe, it is sometimes called a pod, in which case it is attached with a Hardpoint#Pylon, pylo ...

. Each pair was mounted on two V-struts and two wider-spread inverted V-struts to the forward and central spars. The upper engine mountings were braced together centrally by a narrow-chord structure which acted as an auxiliary wing as well as being part of the main wing bracing structure. With a span of almost , it reached out beyond the engines.

Operational history

The Do S's first flight was made on 23 September 1931 from the

Bodensee Lake Constance (, ) refers to three Body of water, bodies of water on the Rhine at the northern foot of the Alps: Upper Lake Constance (''Obersee''), Lower Lake Constance (''Untersee''), and a connecting stretch of the Rhine, called the Seerhei ...

. On 16 November 1931 it flew from

Friedrichshafen Friedrichshafen ( or ; Low Alemannic: ''Hafe'' or ''Fridrichshafe'') is a city on the northern shoreline of Lake Constance (the ''Bodensee'') in Southern Germany, near the borders of both Switzerland and Austria. It is the district capital (''K ...

to Paris for the 12th annual Salon (aero show), landing on the

Seine The Seine ( , ) is a river in northern France. Its drainage basin is in the Paris Basin (a geological relative lowland) covering most of northern France. It rises at Source-Seine, northwest of Dijon in northeastern France in the Langres plat ...

Suresnes Suresnes () is a commune in the western inner suburbs of Paris, France. Located in Hauts-de-Seine, from the centre of Paris, it had a population of 49,482 as of 2020. Suresnes borders the Bois de Boulogne in the 16th arrondissement of Paris, ...

but displayed indoors in Paris. It returned to Friedrichshafen in the new year in a series of short demonstration flights. Despite Dornier's efforts. no orders were placed and only one Do S was built. It was used as a hydrodynamic test vehicle until 1933, when it was transferred at the Ministry of Transport's request to the

Deutsche Verkehrsfliegerschule The Deutsche Verkehrsfliegerschule (DVS), German Air Transport School, was a covert military-training organization operating as a flying school in Germany. It began during the Weimar Republic in Staaken, Berlin in 1925 and its head office was tr ...

(DVS) flying school at List auf Sylt. It was lost in the

Baltic Baltic may refer to: Peoples and languages *Baltic languages, a subfamily of Indo-European languages, including Lithuanian, Latvian and extinct Old Prussian *Balts (or Baltic peoples), ethnic groups speaking the Baltic languages and/or originatin ...

in 1935.

Specifications

References

{{Dornier aircraft Four-engined push-pull aircraft Flying boats 1930s German airliners Dornier aircraft High-wing aircraft Aircraft first flown in 1930