The Nieuport Triplane of 1916-17 was a very unusual design, with the middle wing thrust well forward of the upper wing. This arrangement was meant to improve the pilot's view, but the aircraft was unstable and didn't enter production.
Gustave Delage, the main Nieuport designer, produced at least two triplane designs. The first appeared in 1915 and was a fairly unusual aircraft, but the more famous triplane, of 1916, was even stranger. On this aircraft the middle wing was furthest forward, attached to the front of the upper fuselage longerons, placing it level with the top of the fuselage. The lower wing was level with the bottom of the fuselage and was a little way back, with its trailing edge below the cockpit. The upper wing was furthest back, and was behind the cockpit. The idea was to improve the view for the pilot.
At least two of these aircraft were produced, one using a standard Nieuport 17 fuselage the second a Nieuport 17bis fuselage with more streamlined fairings on the side.
The first of these aircraft under went official French trials, but wasn't ordered into production and never received an official designation. A similar aircraft was later tested by the RFC early in 1917 but also rejected as being worst than the best current RFC scouts.
The second went to the RNAS in March 1917. It was tested by No.11 (Naval) Squadron, but was off their books by 27 June. The triplane underwent tests against a Nieuport 17bis while with the squadron, and was judged to be slightly faster near the ground, but it was unserviceable by 3 May 1917.
The unusual wing layout wasn't a success, and gave the aircraft poor flying characteristics (including making it very unstable in flight), explaining the lack of production orders.
Engine: La Rhône
Power: 110hp or 120hp
Span: 26ft 3.5in
Length: 19ft 2.5in
Height: 7ft 5in
Empty weight: 919lb
Maximum take-off weight: 1,386lb
Max speed: 110hp at 3,000ft
Climb Rate: 13.6m to 10,000ft