The Nieuport 17bis C.1 (or Nieuport XVIIbis C.1 in contemporary sources) was a World War I French single-seat sesquiplane fighter that was produced under licence in the United Kingdom in small numbers for the Royal Naval Air Service. Development The Nieuport 17bis designation was initially used by Nieuport for a Nieuport 11 variant that had been retrofitted with the wings and side fairings from a Nieuport 17, however this type was not produced in any numbers and the designation was reused. The Nieuport 17bis was the first of the vee strut scouts to feature a fully streamlined fuselage, with longitudinal stringers to fair out the shape. Other than the changes to the fuselage, minimal alterations were made, and unlike the later 24, 24bis and 27, the flying surfaces remained the same as used on the 17, as was much of the internal structure. Unlike the 17, or any of the other Vee strutters, it had the Vickers Machine Gun offset to the port (left) side of the centerline. Due to shortages of Le Rhône rotaries, they were fitted with the Clerget 9B rotary instead of the lighter Le Rhône 9J used in most of the other Nieuport single seat scouts. A few examples were fitted with the lower powered Clerget 9Z. As a result of the Clerget's slightly greater diameter, the cowling was ballooned out slightly to provide clearance. The majority of Nieuport 17bis were operated by 6 (Naval) Squadron, who tested them against a Sopwith Triplane and a Sopwith Camel. It was found to have similar manoeuvrability to the Triplane and have a higher dive speed, but was slightly slower at altitude and had heavier controls. Climb rates varied, and in the first test the 17bis outclimbed the Triplane by a significant margin, however in the second test the times to altitude were identical between the two types. The Camel was marginally faster at sea level but had a lower rate of climb while the speed advantage gradually disappeared with altitude. Adding a Lewis machine gun to the Vickers reduced the climb rate, and increased the time it took to climb to by 2 minutes. Initial reports were impressive, but the Clerget engines lost power quickly between overhauls, and the problem was worse with the British built engines. Many pilots tried to have French-built engines in their aircraft. Some aircraft were also delivered to units with incorrect propellers, which