В.Обухович, А.Никифоров Самолеты Первой Мировой войны

На основе KD был разработан поплавковый одноместный разведчик-истребитель KDW. В серии строился увеличенный вариант под индексами W11 (с двигателем Bz.IV) и W25 (с Bz.III).

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

Brandenburg W 11
   Built during late 1916, the W 11 was a slightly larger and more powerful version of the series-built K.D.W. single-seat fighter seaplane. Only two machines were built - Nos. 988-989. Engine, 200 h.p. Benz Bz IV. Span, 100 m. (32 ft. 9 3/4 in.). Length, 8.2 m. (26 ft. 10 7/8 in.). Height, 3.32 m. (10 ft. 10 5/8 in.). Area, 31.4 sq.m. (339 sq.ft.). Weights: Empty, 935 kg. (2,057 lb.). Loaded, 1,215 kg. (2,673 lb.). Speed, 176 km.hr. (110 m.p.h.). Armament, two Spandau machine-guns.

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

BRANDENBURG W 11 Germany

   A heavier and more powerful derivative of the KDW, the W 11 single-seat twin-float fighter biplane was powered by a 220 hp Benz Bz IVa water-cooled engine and retained the "star” interplane bracing arrangement of its predecessor. Armament consisted of two synchronised LMG 08/15 machine guns, and two prototypes were completed during February-March 1917. No series production was undertaken.

Max speed, 109 mph (176 km/h).
Time to 3,280 ft (1 000 m), 4.0 min.
Range, 217 mis (350 km).
Empty weight, 2,061 lb (935 kg).
Loaded weight, 2,718 lb (1233 kg).
Span, 33 ft 1 2/3 in (10,10 m).
Length, 26 ft 6 7/8 in (8,10 m).
Height, 10 ft 10 3/4 in (3,32 m).
Wing area, 338.2 sq ft (31,42 m2).

J.Herris German Seaplane Fighters of WWI (A Centennial Perspective on Great War Airplanes 2)

Brandenburg W.11

   Following the KDW, Brandenburg constructed three other single-seat floatplane designs during the war. Like the final KDW production series, all were armed with two fixed, synchronized Spandau machine guns.
   The first design developed from the KDW was the Brandenburg W.11, an enlarged KDW powered by a 200 hp Benz Bz.IV engine. Span was enlarged slightly to 10.0 m, length to 8.2 m, and wing area to 31.4 sq. m. The additional power increased speed to 176 km/h (109 mph), but flight characteristics were not improved. With the increased power an increased climb rate would also be expected, but no data survive to confirm that. Only three aircraft, marine numbers 988-990, were built in late 1916 due to the marginal performance improvement over the KDW and the great success of the Brandenburg W12 two-seat fighter.

C.Owers Hansa-Brandenburg Aircraft of WWI Vol.2: Biplane Seaplanes (A Centennial Perspective on Great War Airplanes 18)

Type W.11

   The W.11 was a heavier and more powerful attempt to improve the KDW floatplane fighter. It had the more powerful 200-hp Benz Bz IV engine and was dimensionally slightly larger than the KDW. It retained the star-struts of the earlier design and equipped with two synchronised Maxim 08/15 machine guns, placing it in the ED2MG Class. Only three were constructed in late 1916 and received MNs 988 - 990. MN 988 was destroyed as a static test example.(40) Both remaining W.11 fighters were recorded at Flandern 1, Zeebrugge, in a report of 15 May 1917. MN 989 was recorded at the Hage Repair Depot in November 1918. No flying records have been found to date in the surviving war diaries for these aircraft.

(40) It would appear that a contract for three prototypes was standard in order to have a static test example and two to carry out the flying requirements. If one was lost there would be a stand-by machine to continue the testing without delay. Green and Swanborough state that only two W.11 fighters were produced, ignoring the static test example.

  
Brandenburg W.11 Specifications
Source Typenschau Gray & Thetford SVK MN 990 (988 - 990) Brandenburg 3-View
Span, m 10.10/10.10 10.0 10.100/10.100 10.000/10.000
Chord, m 1.65/1.65 - 1.650/1.650 1.650/1.650
Length, m 8.10 8.2 8.100 8.200
Height, m - 3.32 3.500 3.320
Areas, m2
Wings 31.42 31.4 31.43 -
Ailerons 2.0 - 2.00 1.92
Elevators 1.2 - 1.20 1.13
Rudder 0.64 - 0.64 0.53
Empty Wt, kg 933 935 935 935
Loaded Wt, kg 1,233 1,215 1,233 1,215
Performance
Speed in km/hr 176 176 - -
Time to 1000 m 4 minutes - - -
Time to 1500 m 6.5 minutes - 6.5 minutes -
Time to 2000 m 9 minutes - 9 minutes -
Time to 3000 m 16.5 minutes - 16.5 minutes -
Motor 220-hp Benz 220-hp Benz Bz.IV 220-hp Benz 220-hp Benz