C.Owers Hansa-Brandenburg Aircraft of WWI Vol.1: Landplanes (A Centennial Perspective on Great War Airplanes 17)

Type KDD
  
   The KDD was a two-seat reconnaissance plane derived from the KD and retaining the star-strut arrangement. The biplane was of typical Brandenburg mixed construction. Armament was a single machine gun. The pilot had limited forward view being enclosed in his cockpit by the upper wing and engine cowling in an attempt to streamline the aircraft. The first prototype, 60.56, was not successful although it underwent considerable modifications, including three changes of wings.
   A second machine, 60.57, was built that incorporated all the lessons learned from the first. It too was unsuccessful but survived the war before being destroyed.

Type KDD Specifications
Source Typenschau* PMG Data 60.56
Span, m 11.26 11.27/10.32
Chord, m 1.62/1.62
Length, m 7.75
Empty Wt., kg 820 kg
Loaded Wt., kg 1,184 kg
Motor 160-hp Austro- Daimler 160-hp Daimler
* The Typenschau also records the KDD as the UFAG KDD with the same specifications.

M.Dusing German Aviation Industry in WWI. Volume 1 (A Centennial Perspective on Great War Airplanes 84)

Hansa und Brandenburgische Flugzeugwerke AG (Brand)

Aircraft Development:

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  The third 1916 type was the “KDD” with an Austro-Daimler engine of 160 hp. This was the two-seat reconnaissance version of the “KD” and like that type had the “Star-strut” arrangement for bracing the main surfaces. Two machines were built and sent to UFAG as samples, but no production was undertaken, as it was considered that the strut arrangement was too complex.
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P.Grosz, G.Haddow, P.Shiemer Austro-Hungarian Army Aircraft of World War One (Flying Machines)

Hansa-Brandenburg 60.56 and 60.57

  Concurrent with the Type KD fighter, Brandenburg developed a derivative two-seat version known as the Type KDD, featuring a highly-streamlined airframe. In the spring of 1916, Flars ordered four prototypes: 60.56 powered by a 160 hp Daimler engine, the 60.57 powered by a 200 hp Hiero engine, and two unspecified machines. The purchase contract was signed in August 1916.
  In May 1916 the 60.56 was reported "ready for flight trials in about four weeks." However, before leaving the factory, the wing cellule required rebuilding to increase the wing area. Fitted with a new wing, the 60.56 performed preliminary flight trials in June 1916 before being returned to the factory for further work. The modified 60.56 was rolled out again on 5 July 1916 for flight tests, but these proved disappointing. Flars called for extensive airframe modification to achieve the specified 170 km/h (106 mph) airspeed. Returned to the factory in August and reportedly fitted with a third wing cellule, the 60.56 reappeared for further testing in October 1916. The 60.56 was accepted by the LFT in November 1916.
  The airframe of the second prototype, 60.57, under construction in August and incorporating all improvements, was completed in October 1916 but the Hiero engine was not supplied until March 1917, followed by a visit of the Flars commissioning team (Oberleutnants Korner and von Karman) to Briest that month. The 60.57 was completed on 18 May 1917. Flight tests demonstrated the need for "small improvements, namely increased fin, rudder, and elevator areas to obtain better control characteristics." In July 1917, 60.57 was dispatched to Aspern.
  Flight testing of both the 60.56 and 60.57 prototypes was held to a minimum since pilots voiced a strong aversion to the enclosed cockpit that severely limited visibility and threatened to trap the pilot in event of a crash. And the appearance in October 1916 of the improved Brandenburg Type K (C.II 66.51 and 66.81) with an open pilot's cockpit made further flight investigation of the 60.56 and 60.57 redundant. Both prototypes were listed in the Flek inventory for test purposes in September 1917. 60.56 was reported stored in damaged condition at Flugpark 1 on 20 October 1918, and was offered for sale to the Czechoslovakian government in 1920. The 60.57 was attached to the radio experimental section at Aspern in September 1918.

Brandenburg 60.56 (Type KDD)
Engine: 160 hp Daimler
Wing: Span Upper 11.27 m (36.97 ft)
Span Lower 10.32 m (33.86 ft)
Chord Upper 1.62 m (5.31 ft)
Chord Lower 1.62 m (5.31 ft)
Dihedral Upper 0 deg
Dihedral Lower 0 deg
Sweepback Upper 0 deg
Sweepback Lower 0 deg
Gap 1.71 m (5.61 ft)
Stagger 0.54 m (1.77 ft)
Total Wing Area 29.23 sq m (315 sq ft)
General: Length 7.75 m (25.43 ft)
Track 1.80 m (5.91 ft)
Empty Weight 820 kg (1808 lb)
Loaded Weight 1184 kg (2611 lb)
Maximum Speed: 189 km/hr (117 mph)

E.Hauke, W.Schroeder, B.Totschinger Die Flugzeuge der k.u.k. Luftfahrtruppe und Seeflieger 1914-1918

60. Flugzeuge der Ungarischen Flugzeugfabrik A.G. (Ufag) Budapest und Hansa Brandenburgische Flugzeugfabrik Brandenburg/Briest
60.56 Brandenburg DD (Type KDD) Dm 160
60.57 Brandenburg DD (Type KDD) H 200