The Rohrbach Ro III was a twin-engined, all-metal flying boat built in Germany in the mid-1920s. A development of the Ro II, it could be configured either as an airliner or a reconnaissance aircraft. It was developed into the similar but more powerful Ro IIIa Rodra (Ro + dr(ei) + a), intended only as a military reconnaissance/bomber. Four Ro IIIs were bought by Japan and two Rodras by Turkey.
Dr.-Ing. Adolf Rohrbach gained his initial experience with light-alloy structures for aircraft with Zeppelin at Staaken but in 1922 he founded the Rohrbach Metall-Flugzeugbau GmbH in Berlin. At that time powered aircraft construction was banned in Germany by the Versailles Treaty, so he established a second factory in Copenhagen. His first completed design, the all-metal Rohrbach Ro II was built there, as was the Ro III but the Ro IIIa Rodra was built in Berlin after the Versailles conditions were relaxed in 1926. Completion and flight testing were nonetheless done in Copenhagen.[1]
During its construction the Ro III was known as the Ro II series III, indicating its close similarity to its predecessor. The most obvious difference was a sharp bow to improve seaworthiness. It was advertised in two forms, either as a ten passenger airliner or a long range reconnaissance aircraft.[1]
The Ro III had a cantileverhigh wing of strictly rectangular plan and thick aerofoil section.[1] It had a span of 17.2m (56ft 5in), an aspect ratio of 11.46,[2] high for the time, and 6° of dihedral. Wing construction was similar to that of the Ro II, using duralumin throughout, with nose and rear box spars joined by the ribs and metal skin into a large box girder. It was attached to the fuselage sides at their tops. Balanced rectangular ailerons filled about 35% of the trailing edges out to the tips.[1]
The Ro III was powered by a pair of 270kW (360hp) water-cooled V-12Rolls-Royce Eagle IX engines strut-mounted close together above the wing, their propellers well ahead of the leading edge.[1]
The hull, like the rest of the aircraft, was all-metal and rectangular, with flat sides and top. Its planing bottom was also flat, with two steps. Stability on the water was provided by long, stepless floats on each side, strut-mounted from the wings a little outside the engines and braced to the fuselage with a parallel pair of horizontal struts. The hull tapered in plan to the tail, where the empennage was again rectangular, with a broad fin reaching out beyond the end of the hull and carrying a balanced rudder. The tailplane was mounted on the fin about one third of the way up, braced from below with a single strut on each side, and carried narrow-chordelevators.[1]
There was an open cockpit just ahead of the propeller discs. In military reconnaissance configuration it had a crew of three. Like some other Rohrbach flying boats, the Ro III carried a pair of masts and sails, to be used if the aircraft was forced to put down at sea without engine power.[1]
In the first half of 1926, Rohrbach introduced the Ro IIIa Rodra.[1] The new variant was more powerful, with two 340kW (450hp)Lorraine 12E CourlisW12 water-cooled engines in shorter and more streamlined cowlings, with their honeycomb radiators on the wing underside below them. The wing was mounted on top of the fuselage, its span reduced by 1.45m (4ft 9in), and the ailerons were no longer compensated.[3]
Designed only for the long range reconnaissance bomber role it had side-by-side dual controls and two gun positions, one in the nose and the other closer to the tail than the wing, both equipped with twin machine guns.[3] The nose position was also used for observation and bomb-aiming; the bombs were mounted underwing beyond the floats.[1]
Operational history
Four Ro IIIs were delivered to Japan in 1925 as Rohrbach R-1s. Two of these had their original 270kW (360hp) Eagles engines replaced by 340kW (450hp)Hispano-Suiza or Lorraine 12E Courlis engines, and were re-designated R-2 and R-3. At least one Ro III appeared on the Japanese civil register as J-BHAE and was used by the Japan Airline Co. Mitsubishi bought a licence to build Rohrbach aircraft in Japan but it seems not to have been used.
Two Rodras were sold to the Turkish Navy and based at Smyrna. After four years of operation, they were given a lengthy examination by the German aviation authorities, who found them in good order and with no safety problems.[1]
Two Rodras were bought by and tested by the RAF at Martelsham Heath.[4][dubious–discuss]
Variants
Rodra under construction, January 1927
Ro III
29m (95ft 2in) span, 270kW (360hp)Rolls-Royce Eagle IX engines initially. Four sold to Japan where two were re-engined.
Ro IIIa Rodra
As described, two sold to Turkish Navy.
Specifications (Ro IIIa Rodra)
Rohrbach Ro.III Rodra 3-view drawing from Les Ailes March 31,1927
Data from Les Ailes, March 1927[3] except where noted
Guns: Pairs of machine guns in nose and dorsal positions. total of 2,000 rounds.
Bombs: 1,196kg (2,637lb)
Related Research Articles
The Aichi AB-1 was a result of a 1926 government call for a small, Japanese-built, civil transport biplane able to operate from land or water. It won the contest in both roles but did not reach production as airlines moved from biplanes to monoplanes. Nonetheless, it remained in commercial use well into the 1930s.
The Rohrbach Ro II was an, all-metal, 4 seat reconnaissance and bomber flying boat, designed and produced in Germany in 1923.
The Bernard 160 was a three engine, multi-role monoplane designed in the early 1930s to meet a French government call for aircraft suited to policing and medical duties in its African colonies. Two prototypes were built and tested, but no further orders were placed.
The NVI F.K.34 was a three-seat reconnaissance floatplane built in the Netherlands in 1925 as a private venture in the hope of a Dutch Naval Aviation Service order; two accidents during testing meant that it did not go into production.
The Pfalz D.XV was a German single seat fighter aircraft which was approved for production right at the end of World War I, too late to enter service.
The Caudron C.99 was a French light bomber and reconnaissance aircraft. The only example flew with different engines in the mid-1920s.
The Caudron C.91 was a French single engine biplane with an enclosed passenger cabin seating four. It first flew in 1923.
The Descamps 17 A.2 was a two-seat reconnaissance fighter built under a French government programme of 1923. Two versions, with different engines, were tested and six examples were built under licence by Caudron as the Caudron C.17 A.2.
The SET 2 or Proto-SET 2 was a 1920s Romanian prototype reconnaissance and day-bomber aircraft.
The Rohrbach Ro VII Robbe was an all-metal, twin engine flying boat built in Germany in the 1920s. It could be adapted to commercial or military rôles.
The Potez 50 or Potez 50 A2 was a French two seat military multi-rôle aircraft, first flown in 1931. It did not go into service but seven variants using five different engines were produced, one of them setting several speed with useful load records and another, the Potez 506, setting three altitude world records.
The Wibault 260 R.2 was a contender for a French government contract for a long range, two seat reconnaissance aircraft, issued in 1928. There were eight prototypes in the 1931-2 contest and the Wibault was not selected for production.
The CAMS 80 was an amphibious reconnaissance flying boat flown in the early 1930s. Two were built with different engines and were used by the Aéronavale for VIP transport and equipment development until 1938.
The Nieuport-Delage NiD 540 was a high wing, eight seat, single engine airliner, built in France and first flown in 1930. It did not reach production.
The Neiuport-Delage NiD 690 was a French all-metal, single-engined colonial policing aircraft, built for a competitive government contract. Its unusual rear fuselage gave a wide field of downward machine gun fire. Only two examples were built.
The Potez 24 A.2 was a mid-1920s French biplane intended to replace the Potez 15 as an army observation aircraft. The further improved and larger Potez 25 was preferred for production.
The Dewoitine 14 was a mid-1920s French civil transport, capable of carrying mixture of passengers and freight. The sole example was used in commercial trials.
The SPCA 10 or SPCA Paulhan-Pillard E.5 was a large, all-metal, French reconnaissance and bomber flying boat flown in 1928. Only one was built, and it was lost in a fatal crash during development.
The Cañete Pirata, also known as Hidro Antonio Cañete de Reconocimiento (HACR), was a Spanish military parasol wing, single-engined flying boat flown in the late 1920s. Only one was built.
The Kawanishi K-3 was a Japanese, fast, multi-purpose civil transport aircraft from the early 1920s. Despite its good performance it was eclipsed by the release of Army surplus machines and only one was built.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
