The designation Curtiss JN-5 was given to two different aircraft – first to what became known as the Twin JN and then to a single prototype of an improved model of the Jenny that never entered production.
The first use was short-lived and probably only used unofficially at Curtiss, and the twin engined version was simply known as the Twin JN.
The designation JN-5H was then used for a single JN-4H which was modified to become the prototype for a more capable advanced trainer. Because this involved a separate contract, the aircraft’s serial number was changed, from 38124 to 41358.
The JN-5H was given equal span wings, with a wing span of 30ft (13ft shorter than the JN-4). Two sets of wings were produced, one with the RAF 15 aerofoil and one with the Eiffel 36 aerofoil. It was given a new vertical tail – the almost triangular shape of the JN-4 tail was replaced with one with a semi-circular training edge and a small section jutting forward of the hinge to help balance it (a similar rudder was used on the Model R).
The JN-5H was delivered to the Army in March 1918, but it lost out to the Vought VE-7 in a fly-off to win the advanced trainer contract. After that it was converted back to a JN-4H (presumably by giving it the longer wings), and reverted to its earlier serial number. The VE-7 was ordered as a trainer, but only a handful of the 1,000 ordered as a trainer were completed before the end of the war. It did go on to serve as a fighter with the US Navy.
The aircraft was then used as a test bed at McCook Field. It was used to test a steel-frame wing (combined with the JN-5 rudder). It was later given the standard JN-4H rudder and a 180hp Wright-Hispano engine. It was also photographed with a controllable pitch propeller and experimental rudder with steerable tailskid, so was clearly rebuilt on several occasions.