Further reading

• Germany's giant aircraft of WWI the R-Plane
  R-planes
  R-planes were large German Army bombers in World War I. The R classification was short for Riesenflugzeug . In designations, the manufacturer's name preceded the letter R followed by a Roman numeral, e.g. Dornier Rs.III or Staaken R.XIV.The R-planes were the largest aircraft of World War I...
  
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