| Do R Superwal | |
|---|---|
 | |
| General information | |
| Type | Flying BoatAirliner |
| Manufacturer | Dornier |
| Primary users | Deutsche Luft Hansa |
| Number built | 19 |
| History | |
| First flight | September1926 |
TheDornier Do R Superwal was aflying boatairliner designed and produced by the German aircraft manufacturerDornier.
The Do R was a larger development of theDo J, possessing a larger high-mountedstrut-bracedmonoplane wing and an elongatedfuselage. All but the first three flying boats built were powered by four engines in place of the Do J's two; the manufacturer speculated that up to six engines could be readily installed. A variety of powerplants could be fitted to suit customer preferences. The Do R could typically carry 21 passengers in twocabins; 13 in the forward cabin and eight in the rear; however, on some short demonstration flights, it was capable of carrying as many as 60 passengers.[1]
On 30 September 1926, the first R 2 Superwal conducted its maiden flight; twelve world records for seaplanes were set by the type during early 1927. Several were operated byDeutsche Luft Hansa andSANA. It was also flown by theAviación Militar Española.
The first R 2Superwal, (D-1115), made itsmaiden flight on 30 September 1926. It was powered by a pair of 650 hpRolls-Royce Condor III engines were mounted in tandem in a nacelle above the wing and in line with the hull; one engine drove a tractor propeller and the other drove a pusher propeller. D-1115 was the largest flying boat that could be built in the postwarDornier factory inManzell.[citation needed]
TheSuperwal went into service with Severa and laterDVS inList, both organisations of the German government, tasked to develop military seaplanes, ignoringrestrictions imposed under the Treaty of Versailles. Two more R 2Superwals were built in 1927 for Severa (D-1255 and D-1385). D-1255 was periodically operated byDeutsche Luft Hansa and was namedNarwal. D-1385 was equipped with 800 hpPackard engines, and remained in service until November 1936.[citation needed]
Between 20 January 1927 and 5 February 1927, Dornier Chief Pilot Richard Wagner established twelve world records for seaplanes with a new R4GasSuperwal.[citation needed] This aircraft and eleven more withGnome et Rhône Bristol-Jupiter engines (R4Gas) or 525 hpSiemens-Bristol-Jupiter engines (R4Sas) were delivered to the Italian airlineSocietà Anonima Navigazione Aerea (SANA) andLuft Hansa during 1928 and 1929.[citation needed]
Apart from their use byLuft Hansa, sixSuperwals saw regular service with SANA into the early 1930s on a route along the Italian west coast and on to Spain. Three aircraft were lost during their service. TheSuperwal I-RUDO (equipped withIsotta Fraschini Asso 500 engines) went into service with the Italian Air Ministry in 1934 and became the lastSuperwal in Italian service. At least one aircraft was assembled inSpain byCASA.[citation needed]
The Dornier Do R Superwal was a flying boat airliner that, despite its relatively large size, shared numerous similarities to Dornier's prior flying boats.[1] It had a steppedhull that had a pair of wing stubs to increase lateral stability and counteract the offsetcentre of gravity of the flying boat caused by the position of its elevated engines and high-mounted wing. By placing these elements relatively high, they were better protected from rough seas and corresponding potential to be damaged.[2] The flying boat could carry almost 10 metric tons, having roughly double the payload capacity of the precedingDo J while still achieving the same speed (dependent on engine configuration).[3]
The internal volume of the hull was divided in several watertight compartments by numerousbulkheads; the flooding of one compartment would only have a minor impact on the flying boat's overallbuoyancy.[3] In a typical configuration, directly aft of thebow was a cabin with space for up to 13 passengers. On the port side and to the rear of the forward passenger cabin was the pilot's room, entry to which was through a narrow passage; opposite the pilots room, on the starboard side and aft of the entrance to the hull, was thetoilet.[3] Aft of these rooms and immediately beneath the wing was a total of eight fuel tanks, which had sufficient capacity to permit flights of around 2,000 km (1,243 miles); the fuel tank could be resized or even located elsewhere in the hull at the customer's preference.[4] Behind the fuel tanks were the sizable baggage compartment,mail room, and the rear passenger cabin, which could seat up to eight passengers. Aft of this cabin was an empty void in the hull that could be entered through severalmanholes for inspection and repair purposes.[5]
The wing of the flying boat was of a semi-cantilever design, comprising a moderately thick yet aerodynamically favourable cross-section that had uniform dimensions between the tips and centre point.[2] This was made possible by each half of the wing beingbraced at roughly the middle point of its overhang by a pair ofstreamlinedstruts that directly attached to the wingspars. This arrangement incurred less resistance and lower weight than a full cantilever wing would have.[6] The spars were composed ofsteel and was connected to one another via a series of bridge-like doubleribs which were in turn braced against one another using rods that ran parallel to the spars. The perpendicular distance between these rods was maintained by vertical rods.[7] During assembly, the wings were the final element to be attached. Somewhat unusually, the framework of the hull was assembled upside down and rotated along its longitudinal axis part-way through.[8]
The engine arrangement of the engines being positioned intandem provided several benefits.[4] The centre of gravity of the power plant was positioned directly above that of the overall craft and of the fuel tank, easing both flight and substitution options. The placement of the propellers, one behind the other (thus placing the pusher propeller in theslipstream of the tractor propeller) instead of being abreast, was claimed to have no negative impacts in any aspect; to the contrary, the spiral motion of the slipstream produced by the forward propeller was eliminated by the pusher propeller's rotation in the opposite direction.[4] Fuel was supplied to the engines from the fuel tanks within the hull to a small gravity tank next to the engines via awindmill-driven geared fuel pump.[9]
It was claimed that virtually any pair of engines in the 1,400-2,000 hp range could be installed and that this choice was dependent upon customer preferences.[6] Furthermore, it was stated that the location of the engines above the middle of the wing in no way limited the flying boat to using only two engines intandem; reportedly as many as three sets of double-engines could be accommodated upon the middle section of the wing provided that suitable distance from one another was maintained to account for thepropeller diameters. In the event of a single engine outage, when operated in a twin engine arrangement, it was stated that the flying boat could maintain stable flight on only the one remaining engine while carrying at least two-thirds of full payload.[6] Mid-flight repairs to the engines could be performed, access being achieved via a vertical passage between the tank room and the enginenacelle. Heated air was drawn from the engines to warm the passenger cabins.[10]
Data fromNational Advisory Committee for Aeronautics[11]
General characteristics
Performance
