O.Thetford, P.Gray German Aircraft of the First World War (Putnam)

Kondor D 6
   Further development of the D II with an unusual completely cut-out centre-section which sought to achieve maximum pilot visibility. The fuselage was of steel lube and fabric covered and not ply-skinned as it was in the D I and D II. Engine, 140 h.p. Oberursel U III. Span, 8.25 m. (27 ft. 0 3/4 in.). Length, 5.8 m. (19 ft. 0 3/8 in.). Height, 2.53 m. (8 ft. 3 5/8 in.). Area, 13.8 sq.m. (149 sq.ft.). Weights: Empty, 420 kg. (924 lb.). Loaded, 645 kg. (1,419 lb.).

W.Green, G.Swanborough The Complete Book of Fighters

KONDOR D 6 Germany

   Developed by Walter Rethel in the summer of 1918, and powered by a 145 hp Oberursel Ur III rotary engine, the D 6 represented an attempt to provide maximum forward and upward visibility for the pilot. Like preceding Kondor fighters, the D 6 had a steel-tube fuselage, but this was fabric- rather than plywood-covered. The normal upper wing centre section was completely deleted, a tripod of struts, each strut of differing length, bracing the upper wing halves to the fuselage. Armament consisted of the usual pair of synchronised LMG 08/15 machine guns of 7,9-mm calibre. Although some flight testing was conducted during the summer of 1918, the curious upper wing arrangement had its shortcomings, including dubious structural integrity. The induced tip drag was twice that of a normal wing, and the D 6 never appeared in the monthly Idflieg reports, development apparently being discontinued at an early stage.

Max speed, 106 mph (170 km/h).
Endurance, 1.5 hrs.
Empty weight, 926 lb (420 kg).
Loaded weight, 1,422 lb (645 kg).
Span, 27 ft 0 4/5 in (8,25 m).
Length, 19 ft 0 1/3 in (5,80 m).
Height, 8 ft 3 1/2 in (2,53 m).
Wing area, 148.54 sq ft (13,80 m2).

J.Herris German Aircraft of Minor Manufacturers in WW1. Vol I (A Centennial Perspective on Great War Airplanes 49)

Kondor D.II & D.VI

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   The Kondor D.VI did not appear at any of the fighter competitions. It was an interesting attempt to improve the pilot's field of view forward and upward by completely eliminating the wing center section. The D.VI was clearly related to the earlier D.II, but the revised wing design was structurally and aerodynamically problematic. In particular, induced drag from wingtip vortices from the upper wing was twice that of a normal design, which further limited its already modest speed and climb.
   The Kondor D.III, D.IV, and D.V were apparently unbuilt designs, making the D.VI the next design after the D.II.

Kondor D.VI Specifications
Engine: 110 hp Oberursel Ur.II
Wing: Span 8.25 m
Wing Area 13.80 m2
General: Length 5.80 m
Height 2.41m
Empty Weight 420 kg
Loaded Weight 645 kg
Maximum Speed: 170 km/h