O.Thetford, P.Gray German Aircraft of the First World War (Putnam)
Siemens-Schuckert D. Dr I
This extremely unusual triplane fighter was built during 1917 and powered by two high-compression Sh I engines giving 120 h.p. The engines were mounted fore and aft of the central nacelle in "push-pull" fashion, and the tail assembly was carried on tubular outrigger booms. Aerodynamic problems were not fully appreciated or understood, and this interesting prototype crashed on its maiden flight in November 1917; it was not rebuilt. Engines, 2 x 120 h.p. Siemens-Halske Sh I. Span, 10.9 m. (39 ft. 9 1/4 in.). Length, 5.8 m. (19 ft. 0 3/8 in.). Area, 30 sq.m. (324 sq.ft.). Weights: Empty, 680 kg. (1,496 lb.). Loaded, 910 kg. (2,002 lb.). Armament, twin Spandau machine-guns.
W.Green, G.Swanborough The Complete Book of Fighters
SIEMENS-SCHUCKERT (SSW) Dr I Germany
In parallel with development of the D II, the SSW evolved a single-seat triplane fighter, the Dr I. First flown in July 1917, the Dr I was powered by a 110 hp Siemens-Halske Sh I nine-cylinder rotary engine and employed a D I fuselage. In the course of flight testing, the Dr I crashed and was seriously damaged. During reconstruction the wing area was increased by 31.22 sq ft (2,90 m2), and in this rebuilt form the fighter climbed to an altitude of 15,420 ft (4 700 m) in 20.6 min. A development of the design, the Dr II with a 160 hp Sh III engine, was discontinued at an advanced stage in construction. The following data relate to the Dr I prior to reconstruction.
Empty weight, 1,124 lb (510 kg).
Loaded weight, 1,532 lb (695 kg).
Span, 28 ft 2 5/8 in (8,60 m).
Length, 17 ft 4 2/3 in (5,30m).
Wing area, 194.83 sqft (18,10 m2).
SIEMENS-SCHUCKERT (SSW) DDr I Germany
Dubbed unofficially the ‘‘Flying Egg”, the DDr I represented one of the earliest examples of the twin-engined centreline thrust concept, 120 hp Sh Ia rotary engines being mounted fore and aft of the pilot in an abbreviated nacelle, with the tractor engine driving a two-bladed propeller and the pusher engine driving a four-blader. An equi-span staggered triplane with the rudders and elevator carried by tubular steel outriggers, the DDr I carried an armament of two synchronised 7,9-mm LMG 08/15 machine guns. The design found favour with the Idflieg, to which it was presented in June 1917, the prototype flying for the first time in November, but crashing on its maiden flight. Engine control problems and inadequate stability revealed during the brief flight of the DDr I led to cancellation of a more powerful version of the basic design, the DDr II with Sh III engines.
Empty weight, 1,499 lb (680 kg).
Loaded weight, 2,006 lb (910 kg).
Span, 35 ft 9 1/8 in (10,90 m).
Length, 19 ft 0 1/4 in (5,80 m).
Wing area, 322.93 sq ft (30,00 m2).