Rohrbach Ro X

Rohrbach Ro X Romar
The "Romar" during testing in Travemünde
Type:	Traffic flying boat
Design country:	German Empire
Manufacturer:	Rohrbach
First flight:	August 7, 1928
Commissioning:	1929
Production time:	1928-1931
Number of pieces:	4th

The Rohrbach Ro X Romar is a flying boat from the 1920s and the last model from Rohrbach Metallflugzeugbau before it was taken over by Weserflug GmbH . It was supposed to be used on the transatlantic air connections of Luft Hansa , but was ultimately only produced in small numbers.

development

On August 8, 1927, Luft Hansa bei Rohrbach commissioned the development of a long-haul flying boat that should be able to carry twelve passengers or 1,100 kg of cargo plus four crew members over a distance of 4,000 km. Seaworthiness should be guaranteed up to swell 5. The developers based the design on the twin-engine Robbe II from 1927. They enlarged the design and increased the number of engines to three. The individual assemblies of the first of a total of three Ro Xs with the number 29 ordered were manufactured in the Rohrbach factory in Berlin, then transported to Travemünde to the See test site and assembled there in the summer of 1928. The flying boat, christened “Hamburg” with the registration number D – 1693 , made its maiden flight with Hermann Steindorff almost exactly one year to the day after the order was placed on August 7, 1928 in front of representatives from Luft Hansa and the Reichsmarine . The public presentation took place in October at the ILA in Berlin with the second Romar with work number 30, baptized with the name “Bremen” . In the same month, the DVL continued testing in Travemünde, which was satisfactory. The Romar proved to be a robust and easy-to-steer flying boat and also passed the seaworthiness test up to sea state 5, which was carried out from December 11th to 13th could be fixed directly in the flow area of ​​the engines. In a stormy night from November 16 to 17, 1928, Romar, lying on a buoy in the harbor of the sea pilot station, broke loose and was thrown onto a beach on the Pötenitzer Wiek . Thanks to the robust construction, it did not suffer any major damage and was able to free itself two days later when the water level was a little higher. The only incident worth mentioning during the flight tests concerned the quickly repaired breakage of a float strut, caused by a landing across the swell on the open Baltic Sea. After a winter break, the testing was continued in the spring of next year, during which Steindorff was able to reach a height of 2000 m on April 17, 1929 with a payload of 6450 kg and thus set a world record. After a total of 40 flights, the program was declared successfully completed on May 30th.

Rohrbach chief test pilot Hermann Steindorff (middle) during the type test in Travemünde in August 1928 in front of the Romar

After the prototype tests were completed, Luft Hansa took over the "Hamburg" on July 25, 1929 and began some aptitude tests, which also included a seventeen-hour long-haul flight over 2,680 km. This was completed on August 20 on the Netherlands-Great Britain-Scandinavia-Germany circuit with an average speed of 153 km / h; the required 173 km / h could not be achieved. The range required in the development contract with the corresponding payload was not achieved either, so the decision was made to only use the Ro X on shorter routes in the Baltic Sea region, but with 16 passengers. This also affected the two subsequent flying boats with serial numbers 30 and 31, which were handed over to DLH in August and November 1929 as D – 1734 “Bremen” and D – 1747 “Lübeck” (first flight August 1, 1929).

However, it was no longer used regularly. When the “Bremen” carried out a speed measurement flight at low altitude in Travemünde on September 10, 1929, the right wing came into contact with the surface of the water after the starboard engine failed, which led to an immediate crash. The crew under pilot Kaspar remained uninjured, but the Romar, which sank after damaging the hull and was lifted again a short time later, was not rebuilt due to excessive costs. On November 18, the "Hamburg" was badly damaged in the unsuccessful start of a long-haul flight via Dakar to Pernambuco and ran full, but did not sink due to the built-in swimming chambers. Although it could be towed back to Travemünde, it was no longer repaired either. The remaining Ro X was parked and no longer flown, but was kept in the inventory register until 1933 for insurance reasons and then scrapped.

A fourth Ro X was commissioned by the French in October 1929. They were provided with more powerful drives and called Romar II . The final assembly of the model was carried out in Travemünde in February 1931. On April 1st, the transfer to France began. It was interrupted when a defective radiator had to be ditched at sea state 6 after a nine-hour flight 50 km from Cherbourg. The crew was able to carry out the repairs on site with on-board resources and hand over the flying boat on April 8 at the St. Raphael naval air base near Marseille. When F-AKEM was put into service, it was tested and flown in the Mediterranean area until advancing signs of corrosion led to it being scrapped in early 1933.

construction

The three BMW VI engines of the Romar, arranged in a pressure configuration

The Ro X Romar is a cantilever monoplane in all-metal construction .

hull

The frame is made up of four longitudinal beams and ribs covered with smooth sheet metal. The hull with a 1.47 m draft has two steps , a sharp keel and a cruciform bow. Six bulkheads with watertight doors were supposed to maintain the buoyancy even if two departments had leaked. For fellow passengers, there were two cabins lying one behind the other with a toilet and galley in between, the front for four and the rear for eight passengers.

Structure

The cantilevered wing large stretching has a tight riveted to maintain the buoyancy box spar , are hingedly attached to the nose and end boxes. The leading wing edges contained internal fuel tanks. The large ailerons, which are pulled to the wing tip , also serve as landing aids. The three pressure motors are mounted on struts on the fuselage and on the wing at the level of the support floats.

Tail unit

The cross tail is also made of all metal, the horizontal stabilizer is braced towards the fuselage

Floating mechanism

In addition to the hull, the Ro X has two braced, all-metal support floats located under the wings for buoyancy.

Technical specifications

Three-sided tear

Parameter	Data ( Romar I )	Data ( Romar II )
crew	5	4th
Passengers	12-16
span	36.90 m
length	22.00 m	22.55 m
height	8.50 m	8.47 m
Wing area	170.00 m²
Wing extension	8th
V position	6 °
Wing loading	k. A.	115.9 kg / m²
Empty mass	9,900 kg	k. A.
Preparation mass	k. A.	11,620 kg
Takeoff mass	19,000 kg	19,700 kg
drive	three liquid-cooled twelve-cylinder - four cycle - V-engines with a rigid four-bladed Holzluftschraube (Ø 4.50 m)
Type	BMW VI 5.5 ZU	BMW VIIaU
Take-off power Combat and climb power Rated power Continuous power	650 PS (478 kW) 650 PS (478 kW) on the ground 610 PS (449 kW) on the ground 500 PS (368 kW) at 700 m	690 PS (507 kW) 690 PS (507 kW) on the ground 650 PS (478 kW) on the ground 600 PS (441 kW) on the ground
Fuel volume	maximum 7800 l
Top speed	210 km / h	228 km / h
Range	maximum 4,000 km
Service ceiling	2,800 m

literature

• Hans-Jürgen Becker: Seaplanes - flying boats, amphibians, float planes . In: German aviation . tape 21 . Bernard & Graefe, Bonn 1994, ISBN 3-7637-6106-3 , pp. 135 ff .
• Fred Gütschow: The German flying boats . Motorbuch, Stuttgart 1978, ISBN 3-87943-565-0 , p. 265 ff .
• Wolfgang Müller: The flying ocean cruiser . Publishing house M&M, Martenshagen 2017, ISBN 978-3-939155-79-9 .
• Karl-Dieter Seifert: German air traffic 1926–1945 - on the way to world traffic . In: German aviation . tape 28 . Bernard & Graefe, Bonn 1999, ISBN 3-7637-6118-7 , pp. 137 ff .

Web links

Commons : Rohrbach Ro.X Romar  - Collection of images, videos and audio files

Individual evidence

1. ↑ Seifert, page 362
2. ↑ Peter All-Fernandez (ed.): Aircraft from A to Z . tape 3 . Bernard & Graefe, Koblenz 1989, ISBN 3-7637-5906-9 , pp. 272 .
3. ↑ Becker, page 137