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

B.F.W. N I
   An experimental two-seat triplane night bomber, of which only one was built to carry 744 kg. (1,636 lb.) of bombs! Engine, 260 h.p. Mercedes DIVa. Weights: Empty. 1,500kg.(3,300 lb.). Loaded,2,500kg.(5,500 lb.). Armament, one Parabellum machine-gun. No photograph available.

J.Herris Nachtflugzeug! German N-types of WWI (A Centennial Perspective on Great War Airplanes 3)

BFW N.I
  
   In August 1917, Idflieg contracted with the Bayerische Flugzeug Werke (BFW) of Munich to design and build three prototype N.I night bombers. These were to be powered by a 260 hp Mercedes D.IVa engine and be capable of lifting a 500 kg bomb load. A flight duration of four hours was specified.
   The dates of the prototype's completion and first flight are not known. In the fall of 1918, the triplane was fitted with test probes (venturi tubes) to explore the airflow around the airframe and determine the specific glide ratio. During these test flights two crewmen were carried to read and record the data. After the war, one BFW N.I "in repairable condition with engine" was stored at a government depot.
   The fuselage was well-streamlined with good nose entry from a spinner, but the large, flat-plate radiator beneath the top wing doubtless contributed a lot of drag. The BFW N.I appears to have been an attempt to carry a bombload nearly as large as the twin-engine night bombers being used but with only one engine. The bomb load was heavy for a single-engine airplane, and the gunner had a flexible machine gun for defense. The triplane layout was likely chosen to give the required large wing area with moderate span for better maneuverability. Few details of its performance or flying qualities have survived.

J.Herris Otto, AGO and BFW Aircraft of WWI (A Centennial Perspective on Great War Airplanes 37)

BFW N.I

   In August 1917, Idflieg contracted with the Bayerische Flugzeug Werke (BFW) of Munich to design and build three prototype N.I night bombers. These were to be powered by a 260 hp Mercedes D.IVa engine and be capable of lifting a 500 kg bomb load. A flight duration of four hours was specified.
   The dates of the prototype's completion and first flight are not known. In the fall of 1918, the triplane was fitted with test probes (venturi tubes) to explore the airflow around the airframe and determine the specific glide ratio. During these test flights two crewmen were carried to read and record the data. After the war, one BFW N.I "in repairable condition with engine" was stored at a government depot.
   The fuselage was well-streamlined with good nose entry from a spinner, but the large, flat-plate radiator beneath the top wing doubtless contributed a lot of drag. The BFW N.I appears to have been an attempt to carry a bombload nearly as large as the twin-engine night bombers being used but using only one engine. The bomb load was heavy for a single-engine airplane, and the gunner had a flexible machine gun for defense. The triplane layout was likely chosen to give the required large wing area with moderate span for better maneuverability.
   The ungainly BFW N.I could carry a heavy bomb-load for a single-engine aircraft and seems to have been a reasonable candidate for production. Certainly it was closer to meeting its design requirements than BFW's CL-prototypes. However, it was very slow, which would have presented problems in operational service.
   The existing N-types in service, the AEG N.I and Sablatnig N.I, were not stellar designs and the BFW N.I appeared to be a reasonable alternative. However, German night bomber pilots preferred the twin-engine aircraft, the Gothas, AEGs, and Friedrichshafen G-types they were already flying, and Idflieg decided not to purchase any more N-types.
   Few details of its performance or flying qualities have survived.


BFW N.I Specifications
   Engine 260 hp Mercedes D.IVa
   Wing Span (Upper) 15.006 m (49.2 ft.)
   Length 9.38 m (30.78 ft.)
   Empty Weight 1,500 kg (3,307 lb.)
   Loaded Weight 2,500 kg (5,512 lb.)
   Maximum Speed 110 kmh (66 mph)
   Armament 1 flexible machine gun, 744 kg bombs