Rohrbach Ro III

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Rohrbach Ro III
Ro III of the Turkish Navy in November 1930
Ro III of the Turkish Navy in November 1930
Type: ocean-going flying boat
Design country:

German EmpireGerman Empire German Empire

Manufacturer:

Rohrbach Metal Aeroplan A / S, Copenhagen

First flight:

1925 (Ro III), 1926 (Ro IIIa)

Number of pieces:

7 or 9? (up to 7 to Japan ?, 2 to Turkey)

The Rohrbach Ro III was a seaworthy flying boat from the German manufacturer Rohrbach Metallflugzeugbau from the 1920s, which was offered as a long-range reconnaissance and passenger flying boat . The further development from the Rohrbach Ro II is also expressed in the original factory name Ro II Series 3. The information on the number of Ro III and Ro IIIa built in total vary between four and nine copies.

Rodra under construction in early 1927

history

Ro III

Despite the overall good assessment of the Ro II sold to Japan (referred to there as R-1), it was above all the poor starting properties that were the subject of suggestions for improvement. Rohrbach introduced corresponding improvements in the successor model. A sharp boat bow was introduced, which was also to become a feature of all later Rohrbach constructions. In addition, the frame construction of the boat floor was reinforced. In addition to a slight change in dimensions compared to the Ro II, the Ro III also received a stripped horizontal stabilizer.

Mitsubishi took over a Ro III in 1927 under the designation R-2 with Hispano-Suiza V-12 engines produced under license, each with an output of 450 hp. The instruments were also made in Japan. After a test phase and a conversion to Rolls-Royce Eagle IX engines, the aircraft was handed over to the airline Nippon Koku KK (Japan Aviation Co. Ltd.) in September 1927 and was given the J-BHAE registration . However, the use on the planned route to Shanghai did not materialize because of the unsatisfactory testing.

Based on this experience, the Hiro Marine Arsenal , which received the components for the second machine from Berlin, changed some important things in the R-3 . In addition to rounded wing ends, streamlined struts, a raised horizontal stabilizer and modified support floats, the most important innovation was a keeled (V-shaped) fuselage floor. Two Lorraine-Dietrich engines with 450 hp each served as drive. Despite improved performance, however, there was no license production in Japan.

Ro IIIa (Rodra)

Rohrbach also recognized the need for further development of the design beforehand and designed the Ro IIIa Rodra (Ro-three-a). In the first half of 1926 the Rodra was presented as a flying boat intended primarily for military purposes. The machine received special drop devices for a bomb load of up to 1196 kg, which could be carried under the wings. The Rodra received a strongly keeled fuselage floor, which replaced the flat floor previously used, as the non-keeled design was exposed to considerable impacts at the high touchdown speeds of the Rohrbach flying boats. These affected both the crew and the structure of the airframe . The keel resulted in a softer immersion of the hull boat. The crew could be reduced from four to three men. The engines used were Lorraine-Dietrich engines with 450 hp each.

Against strong foreign competition Rohrbach was able to sell two Ro IIIa to the Turkish Navy. These were given the names Smyrna and Stambul . After more than four years of use, the two aircraft were assessed by the German Aviation Research Institute. This established that all components were in order and full operational safety was guaranteed.

construction

The Ro III was designed as a shoulder-wing aircraft, with the wings having a rectangular plan. These were subdivided several times and had a profile thickness that remained constant over the span. Rohrbach attached importance to the simple repair of possible corrosion damage by easily removing and riveting the planking. The strong V-position of 6 ° prevented undercutting the wing tips in heavy seas. The front and rear spars, together with cross braces, ribs and planking, formed the torsionally and flexurally rigid box spar. The wing nose and end ribs also formed individual boxes that were screwed to the central box spar. These boxes were easy to change and simplified spare parts inventory by dividing them into sections of equal size. In the area of ​​the inner wing, the end rib boxes served as fuel tanks.

The two-tier, narrow boat hull was divided into watertight spaces by several bulkheads and was made of the material duralumin throughout . The tail surfaces also had a rectangular shape, with the horizontal tail being braced towards the fuselage. The two support floats attached under the wings also had struts to the fuselage and the wing. In the version as a commercial flying boat, ten people could be accommodated in the relatively narrow hull, while in the military version the crew consisted of 3.

The engines sat on bearing blocks welded from steel profiles above the wing, where, like the two-bladed wooden propellers, they were largely protected from splashing water. The small distance between the engines resulted in good longitudinal stability in single-engine flight. For rescuing the flying boat from the water and for maneuvering on land, there was a so-called "rescue vehicle" per wing on which the flying boat could roll into the water and back on land with its own power. The car could be put on and taken off with two men in four minutes. The auxiliary sails provided for emergencies on the Ro II have been further improved on the Ro III.

Technical specifications

Three-sided view Ro IIIa (Rodra)
Parameter Data Ro III Data Ro IIIa
crew 3-4 3
length 17.20 m 17.20 m
span 29.00 m 27.55 m
Empty mass 3600 kg 3900 kg
Takeoff mass 6300 kg 6250 kg
Top speed 200 km / h 190 km / h
Cruising speed 180 km / h
Landing speed 100 km / h
Service ceiling 4000 m 3300 m
Engines 2 × Rolls-Royce Eagle IX with 360 hp each 2 × Lorraine-Dietrich V-12 with 450 HP each

See also

literature

  • Fred Gütschow: The German flying boats - flying boats, amphibious flying boats and projects from 1909 to the present . Motorbuch Verlag, 1978, ISBN 3-87943-565-0 , pp. 246-252
  • Hans-Jürgen Becker: Seaplanes - flying boats, amphibians, float planes (Die deutsche Luftfahrt Volume 21) , Bernard & Graefe Verlag, 1994, ISBN 3-7637-6106-3 , p. 130 f.

Web links

Commons : Rohrbach Ro.III Rodra  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Helmut Stützer: The German military aircraft 1919–1934 , 1984, pp. 183, 190
  2. ↑ Mention of the Mitsubishi R-2 on airhistory.org.uk (accessed February 12, 2017)
  3. ^ Photo of the Kastenholm on Flight from July 17, 1924
  4. ↑ Recovery vehicle for landing the flying boat (here at the Ro II)
  5. ↑ Gütschow, 1978, p. 248
  6. ^ Gütschow, 1978, p. 252