The DFW R.II (company designation T26 II) was a

heavy bomber Heavy bombers are bomber Fixed-wing aircraft, aircraft capable of delivering the largest payload of air-to-ground weaponry (usually Aerial bomb, bombs) and longest range (aeronautics), range (takeoff to landing) of their era. Archetypal heavy ...

() aircraft designed by the (DFW) during the

First World War World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

for the

Imperial German Army The Imperial German Army (1871–1919), officially referred to as the German Army (), was the unified ground and air force of the German Empire. It was established in 1871 with the political unification of Germany under the leadership of Kingdom o ...

's ()

Imperial German Air Service Imperial is that which relates to an empire, emperor/empress, or imperialism. Imperial or The Imperial may also refer to: Places United States * Imperial, California * Imperial, Missouri * Imperial, Nebraska * Imperial, Pennsylvania * Impe ...

(). Six aircraft were ordered in late 1916; of these three were completed, two were unfinished when the war ended in November 1918 and the last was cancelled. None of the aircraft flew any combat missions.

Design and development

The Imperial German Air Service wanted an improved version of the R.I with a greater payload. The same arrangement of four inline engines mounted in the

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 ...

, driving two tractor propellers and two pusher propellers via long

driveshaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power, torque, and rotation, usually used to connect ...

s was used. Having learned from the experiences with the R.I, the engine mounts of the R.II were built from pressed steel integrated with the fuselage frames. The shorter

crankshaft A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...

s of the Mercedes D.IVa

straight-six A straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine balanc ...

piston engines in the R.II did not cause any new problems, but the aircraft still had vibration problems. These were traced to the high rotational speeds of the driveshafts; they were enclosed within stiffener tubes with

ball bearing A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...

s, which fixed the problem.

Operational history

Of the six ordered by the

Luftstreitkräfte The ''Deutsche Luftstreitkräfte'' (, German Air Combat Forces)known before October 1916 as (The Imperial German Air Service, lit. "The flying troops of the German Kaiser’s Reich")was the air arm of the Imperial German Army. In English-langu ...

, only three were completed before the end of the war. The first aircraft was delivered to the R-plane Training Unit () at

Cologne Cologne ( ; ; ) is the largest city of the States of Germany, German state of North Rhine-Westphalia and the List of cities in Germany by population, fourth-most populous city of Germany with nearly 1.1 million inhabitants in the city pr ...

on 1 April 1918 where it flew training missions for the rest of the war because its performance, reliability and load-carrying capability were significantly inferior to the

Zeppelin-Staaken Zeppelin-Staaken (sometimes ), was a German aircraft manufacturer originally named (Experimental Works Gotha-East (V.G.O.)) when it was formed in mid-1914 by Count Ferdinand von Zeppelin and Robert Bosch. The company rented facilities in Gotha wit ...

aircraft like the R.VI. The second aircraft was ready for operational service in October and the third made its first flight on 22 July. Following the war, DFW planned to convert the two unfinished aircraft into

airliner An airliner is a type of airplane for transporting passengers and air cargo. Such aircraft are most often operated by airlines. The modern and most common variant of the airliner is a long, tube shaped, and jet powered aircraft. The largest ...

s which would have carried 24 passengers, but the aircraft were scrapped instead.Haddow & Grosz, pp. 94–96

Specifications R.II (15/16)

Notes

Bibliography

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External links