A Riesenflugzeug (plural Riesenflugzeuge, German for "giant aircraft"), sometimes colloquially referred to in English as an R-plane, was any member of a class of large World War I German bombers, possessing at least three aircraft engines, although usually four or more engines. These large multi-engine aircraft could fly several hours with larger bomb loads than the smaller Grossflugzeug bombers such as the Gotha G.V.

Some of the earliest Riesenflugzeuge were given G-type designations before being redesignated, but a major distinction was that the requirements for the R-type specified that the engines had to be serviceable in flight. As a result, designs fell into two groups: those with the engines mounted centrally inside the fuselage using gearboxes and driveshafts to transfer the power to propellers mounted between the wings, and those with conventional powerplant installations mounted in large nacelles or the nose of the aircraft where engineers would be stationed for each group of engines.

The transmission of power from the centrally mounted engines to the remote, most often wing-mounted propellers proved troublesome in practice, and most operational examples of Riesenflugzeug-class aircraft were of the second type, as with the all-direct-drive Zeppelin-Staaken R.VI.

The Idflieg (Inspektion der Fliegertruppen (Inspection of the Air Force), the German Army department responsible for military aviation), assigned the letter R to this type of aircraft, which would then be followed by a period and a Roman numeral type number. Seaplanes were denoted by adding a lowercase "s" after the "R" in the designation.

The Riesenflugzeuge were the largest airplane of World War I. In comparison, the largest equivalent Allied airplane were the Sikorsky Ilya MurometsThe first successful large aircraft, and the inspiration for the German Grossflugzeug and Riesenflugzeuge bombers with a span of , the Caproni Ca.4 with a span of , the one-off Felixstowe Fury flying boat with a span of and the Handley Page V/1500 with a span of . The Riesenflugzeuge that bombed London during the First World War were larger than any of the German bombers in use during the Second World War.The span Junkers Ju 390, was only used as a transport, and the Focke-Wulf Fw 200 Condor, used for maritime operations had a span of . The largest built, the Siemens-Schuckert R.VIII of 1918, had a wingspan of . It was not until sixteen years later that an airplane with a larger wingspan, the Soviet Tupolev Maksim Gorky eight-engined monoplane, was built with a wingspan.

The Riesenflugzeuge were operational from 1915 to 1919 and most of them were built as "one-off" aircraft.

List of aircraft TypeEnginesSpanFirstflightServiceNotesNumber builtAEG R.I4 × 260 hp Mercedes D.IV1916NoneBroke up in flight in 19181 completed7 partially builtDFW R.I4 × 220 hp Mercedes D.IV1916Eastern frontCrashed on 2nd combat flightHaddow, 1962, p.671DFW R.II4 × 260 hp Mercedes D.IVa 1918Trainer as unsuitable for combat 2 of 6 orderedDFW R.III8 × 260 hp Mercedes D.IVn/aNoneIncomplete at end of war, cancelled NoneJunkers R.In/aNone 1 incompleteLFG Roland R.I4 × 1000 hp Maybach Mb.IVn/an/aNone Not builtLinke-Hofmann R.I4 × 260 hp Mercedes D.IVa1917NoneFirst example had spanHaddow, 1962, p.67 4 Linke-Hofmann R.II4 × 260 hp Mercedes D.IVa1919NoneUsed largest single propeller ever built, some 6.9 meters in diameter 2Mannesmann Giant TriplaneG. Sollinger, "The Forssman Tri-plane, The Largest Aeroplane Of World War I" The Forssmann-Triplane10 × unk. enginesn/aNoneCancelled incomplete Nonen/aNoneDesign study onlyNone2 × 110 hp Mercedes D.III& 2 × 220 hp Mercedes D.IVa1915Trainer After several rebuilds it was accepted by the military in 1916.Scrapped after breaking in two.1Siemens-Schuckert R.I3 × 150 hp Benz Bz.III1915Eastern front & trainingHaddow, 1962, p.671Siemens-Schuckert R.II3 × 260 hp Mercedes D.IVa1915TrainingSpan increasedHaddow, 1962, p.671Siemens-Schuckert R.III3 × 220 hp Benz Bz.IV1915TrainingHaddow, 1962, p.671Siemens-Schuckert R.IV3 × 220 hp Benz Bz.IV1916TrainingSpan increasedHaddow, 1962, p.671Siemens-Schuckert R.V3 × 220 hp Benz Bz.IV1916Eastern frontSpan increasedHaddow, 1962, p.671Siemens-Schuckert R.VI3 × 220 hp Benz Bz.IV1916Eastern frontSpan increasedHaddow, 1962, p.671Siemens-Schuckert R.VII3 × 260 hp Mercedes D.IVa1917Eastern frontHaddow, 1962, p.671Siemens-Schuckert R.VIIIn/aNone 2 (one unfinished)Siemens-Schuckert R.IXn/an/aNoneDesign study onlyNoneZeppelin-Lindau Rs.I3 × 240 hp Maybach Mb.IVn/aNoneWrecked unflown, 1915. Flying-boatdeveloped by Claudius Dornier while working for Zeppelin.1Zeppelin-Lindau Rs.II3 × 240 hp Maybach Mb.IV1916NoneFlying boat1Zeppelin-Lindau Rs.III3 × 245 hp Maybach Mb.IVa1917EvaluationFlying boat1Zeppelin-Lindau Rs.IV4 × 245 hp Maybach Mb.IVa1918NoneFlying boat1Zeppelin-Staaken VGO.I3 × 240 hp Maybach HSor 5 × 245 hp Maybach Mb.IVaThe essentially same wing structure was used for nearly all 42.2 meter wingspan Zeppelin R-series aircraft.1915Kaiserliche MarineBuilt at Versuchsbau Gotha OstBuilt at Versuchsbau Gotha Ost to Zeppelin design1Zeppelin-Staaken VGO.II3 × 240 hp Maybach HS1915Eastern front & trainerHaddow, 1962, p.671Zeppelin-Staaken VGO.III6 × 160 hp Mercedes D.III1916Eastern frontHaddow, 1962, p.671Zeppelin-Staaken R.IV2 × 160 hp Mercedes D.III& 4 × 220 hp Benz Bz.IV1916Eastern front & Western front 1Zeppelin-Staaken R.V5 × 245 hp Maybach Mb.IVa1916Western front 1Zeppelin-Staaken R.VI4 × 260 hp Mercedes D.IVa1916Western front 18Zeppelin-Staaken R.VII2 × 160 hp Mercedes D.III& 4 × 220 hp Benz Bz.IV1917NoneWrecked during flight to the front.1Zeppelin-Staaken R.VIII8 × 260 hp Mercedes D.IVaor 8 × 245 hp Maybach Mb.IVa1918NoneUnfinishedHaddow, G.W.; Grosz, Peter M. (1962). The German Giants, The Story of the R-planes 1914–1919. London: Putman.Gunston, Bill, 1991. Giants of the Sky: The Largest Aeroplanes of All Time. Sparkford, UK: Patrick Stephens Limited.1 incompleteZeppelin-Staaken R.IX8 × 260 hp Mercedes D.IVaor 8 × 245 hp Maybach Mb.IVa1918NoneUnfinishedHaddow, G.W.; Grosz, Peter M. (1962). The German Giants, The Story of the R-planes 1914–1919. London: Putman.Gunston, Bill, 1991. Giants of the Sky: The Largest Aeroplanes of All Time. Sparkford, UK: Patrick Stephens Limited.1 incompleteZeppelin-Staaken R.XIV5 × 245 hp Maybach Mb.IVa1918Western front 3Zeppelin-Staaken R.XIVa5 × 245 hp Maybach Mb.IVa 42.2 m (138 ft 5.5in)?Post-warSeized while smuggling1Zeppelin-Staaken R.XV5 × 245 hp Maybach Mb.IVa42.2 m (138 ft 5.5in)1918Western front 2Zeppelin-Staaken R.XVI2 × 530 hp Benz Bz.VI& 2 × 220 hp Benz Bz.IV1918AirlinerTwo completed, 3rd unfinishedOne built during war which did not see any service. One was never completed. One was built as a civilian airliner3 (one unfinished)Zeppelin-Staaken L4 × 245 hp Maybach Mb.IVa?NoneFloatplane variant. Wrecked in trials.Built for Kaiserliche Marine14 × 245 hp Maybach Mb.IVa?floatplane airliner 3 built for Kaiserliche Marine3

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Bibliography

External links Brief contemporary technical description of the Dornier Rs.III or Rs.IV, with rough diagrams. "The Four-engine Giant" Notes on German Bombers in 1918 issue of Flight "The Linke-Hofmann Giant Machines", p.2, p.3 & p.4 in 1919 issue of Flight "The German D.F.W. Commercial Four-Engined Biplane", p.2, p.3, p.4 & p.5 in 1919 issue of Flight

Flyingmachines.ru's photo page of many WW I German R-class bombers