The Curtiss JN-4Can ‘Canuck’ was an improved version of the Curtiss JN-3 that was developed independently in Canada, and constructed at the same time as the American Curtiss JN-4.
The Canadian JN-4 was designed by F.G. Eriscon, the Chief Engineer of the Canadian Aeroplanes Ltd. This firm had been founded as Toronto Curtiss Aeroplanes in 1916, but purchased by the Imperial Munitions Board on 15 December 1916. As well as the JN-4, this factory also built the Avro 504 and the Felixstowe F5L flying boat (itself an improved version of the Curtiss H-12). The factory built twelve JN-3s for the RNAS, followed by at least 87 of the American Curtiss JN-4A of November 1916 (although it isn’t clear when this version was produced in Canada).
Both the JN-4A and JN-4Can were developed in response to British requests for improvements to the JN-3. That aircraft had unequal span wings, with ailerons on the upper wings only, and used the Deperdussin control system, with a wheel for the ailerons and a foot bar for the rudder.
The JN-4A had new fuselage lines, enlarged tail surfaces, ailerons on both wings, six degrees of downthrust for the OX-5 engine and a section cut away from the trailing edge of the upper wing centre section. Those examples built in Canada went to both Britain and America.
The JN-4Can was developed independently of the American JN-4 and was instead a development of the JN-3. Like the JN-4A it had a new tail, this time using a new metal frame. The new Canadian tail had a slightly more rounded vertical surface, and an almost semi-circular horizontal surface. The American JN-4 had a much more angular horizontal surface. The Canuck had ailerons on both wings, connected by struts. The Deperdussin controls of the JN-3 and JN-4A was replaced with the stick control system used in British service aircraft (this was later introduced on the JN-4D). It kept the 90hp Curtiss OX engine.
The exact number of the Canadian variant that were built isn’t entirely clear, as the same factory also produced some composite aircraft with American fuselages and Canadian wings, but a total of 1,260 is generally accepted. Of these 680 went to the US Army, including 50 that had been in service at winter flying schools that Canada had created in Texas in 1917 to prevent training being disrupted by the severe winter weather.
At first the Canadian aircraft were simply designated as the JN-4, despite being both slightly later, and more advanced, than the American JN-4. However once they were operating alongside those aircraft a new designation was needed, and they became known as the JN-4Can or JN-4 (Can). However they were informally known as the Canuck, and that name stuck with them.
The Canuck was used by the Canadian military and by the US Army, but doesn’t appear to have entered British service. They remained in use with the Canadian Air Force until 1924, and some were still in civilian use in Canada into the 1930s.