12/31/2012. Remarks by Johan Visschedijk: "The N-9 of late 1916 was essentially a JN-4B fitted with the 100 hp Curtiss OXX engine, a single float, a lengthened center section, and 5 ft (1.52 m) lower wing extensions on each side of the fuselage in the manner of the prototype N-8 in order to carry the additional weight of the floats. The control system was the Deperdussin type with the control wheel operating the ailerons and a foot-bar controlling the rudder. The prototype used JN-4B vertical tail surfaces and oversized ailerons; the vertical fin was enlarged on production models.
The US Army made limited use of the N-9, ordering fourteen early in 1917; the USN was the principal user, ordering a total of 560 as primary trainers. Of these, only 100 were built by Curtiss; the rest (including the pictured one) were from Curtiss's wholly-owned subsidiary, the Burgess Co of Marblehead, Mass. Fifty additional airframes were built up at Navy bases from spare parts in the early 1920s; N-9s remained in USN service into 1927.
Two designations were applied to the USN N-9s. N-9C was not official but came into use after the later N-9H appeared in order to distinguish the original Curtiss-powered N-9s from the later versions. The principal identification point of the N-9C was the exposed cylinder banks of the distinctive Curtiss OXX engine and the use of a nose radiator enlarged slightly over that of the JNs and the N-8 by having a curved area added at the bottom.
The N-9H designation was official, the letter identifying the 150 hp Wright-Hispano engine (also known as the Wright A and the 'Hisso'). This installation differed considerably from the N-9C. The cylinder banks were exposed as on the N-9C but were different in appearance. The use of a large spinner over the propeller hub precluded the use of a nose radiator, so the cooling was done by a large column-like radiator that projected well above the wing. The USN tested some N-9Hs with the 150 hp Curtiss K-6 engine but did not adopt the new powerplant."