O.Thetford, P.Gray German Aircraft of the First World War (Putnam)
Rex Single-Seat Scout
This dainty little scout-type single-seater was built by the Flugmaschine Rex G.m.b.H. early in 1916 and, as may be seen, was an orthodox aircraft of wood and fabric construction. It is reported as having been based on the British Bristol Scout. As far as is known, only this single machine serialled 6/16, was built. Engine, 80 h.p. Oberursel U O.
W.Green, G.Swanborough The Complete Book of Fighters
REX D 6 Germany
Early in 1916, the Flugmaschine Rex Gesellschaft of Koln-Bickendorf produced its first single-seat fighter to the designs of Dipl-Ing Friedrich Hansen, the D 6, which allegedly owed its inspiration to the Bristol Scout. A thoroughly conventional equi-span single-bay biplane, the D 6 was of wooden construction with fabric skinning and was powered by an 80 hp Oberursel (Gnome) U 0 seven-cylinder rotary engine. The first prototype D 6 crashed on its first flight while being flown by its designer from Cologne airfield, but a second example was built, this differing in only minor respects, such as omission of the nose-over structure projecting ahead of the undercarriage. No further details of the D 6 have been recorded, but it may be assumed that performance was insufficient to justify an Idflieg contract.
J.Herris German Aircraft of Minor Manufacturers in WW1. Vol II (A Centennial Perspective on Great War Airplanes 50)
Rex
The Flugmaschinen Rex-Gesellschaft mbH company was established on 14 December 1914 by Walter Gutbire. The company intended to build a Morane-type monoplane and a biplane, similar to the Bristol Scout, but nothing came of this. The first trials of a small biplane were held on the Manne-Herten airfield which, due to rising costs, were curtailed. The same fate befell the design of a rotary engine that was proposed to power the biplane. During these trials a repair facility for military aircraft was established. The company then concerned itself with the repair of aircraft, but also experimented in 1917, by building a fighter the "D17" that was described as an almost exact copy of the Albatros and was never accepted.