Origins When Gustave Delage was appointed as the chief designer of
Nieuport, in January 1914, a series of sesquiplane designs followed. Nieuport had been famous for wire-braced
monoplanes and these had reached the limit of their development. The sesquiplane configuration was adopted by Delage as a compromise between the low drag of a monoplane and the greater strength of a
biplane. The first of Delage's sesquiplanes was the two-seat
Nieuport 10 of 1914, which was followed the next year by the smaller Nieuport 11 single-seater, which in turn was supplemented by the Nieuport 16. The larger engine of the latter aircraft made it nose heavy and increased the wing loading, especially when armed with a synchronised Vickers gun. Developed in parallel with the conservative Nieuport 16, the Nieuport 17 was slightly larger with longer wings and fuselage, improved aerodynamic form and better balance. It was fitted with the
Le Rhône 9J engine and later examples used motors.
Design installed in a Nieuport 17 The upper wings of the Nieuport sesquiplanes used a typical structure for the period, with widely spaced spars connected with full chord
ribs and compression ribs, cross-braced internally with wire and by riblets on the leading edge. The lower wing's single spar was directly below the rear spar of the upper wing and was braced with a characteristic Vee strut. The
horizontal stabilizer,
elevator and
rudder were built up from welded diameter steel tube and controls for these were provided via conventional cables and pulleys. The single spar was behind the centre of lift, which at high speeds could cause the lower wing to twist, increasing the angle of attack until the wing stalled, at which point it would return to its normal position, repeating until the wing snapped or the pilot slowed the aircraft. British Nieuports were modified at No 2 Aeroplane Supply Depot to alleviate this problem. Late in French service, some N.17s had their lower wings replaced with spares intended for the newer Nieuport 24. The fuselage of the 17 was built around four
ash longerons which tapered from the rectangular sheet steel engine mounting to the rudder post, with the upper longerons bowed around the cockpit, giving most of the fuselage a trapezoid cross section. This was braced with spruce struts held with diagonal bracing wires and steel plate joints. The sides and top of the forward fuselage were covered in light molded plywood panels while the rear fuselage sides were covered in fabric. Behind the pilot was a headrest, molded into the plywood top decking, which was supported by longitudinal stringers. Production of the new
Alkan-Hamy synchronization gear permitted the wing-mounted
Lewis gun on the earliest examples to be replaced with a synchronised
Vickers gun mounted on the fuselage to fire through the propeller arc.
Derivatives machine gun Entering service in May 1916 but not named until September, the
Nieuport 21 differed from the 17 primarily in the adoption of the lower powered
Le Rhône 9C or Le Rhône 9Ga engine. This increased endurance and reduced wing loading and was useful for a high-altitude bomber escort but it was rarely employed as such. In French and especially Russian service, the 21 was commonly used with the Nieuport 17 in the same general fighter role, although it was also useful as an advanced trainer. The 21 has commonly been mistaken for the earlier Nieuport 11, as both lacked headrests and used the same cowling and engines, particularly when some Nieuport 11s were also fitted with molded fuselage sides. Like the 17, the 21 is larger and can be identified by the flying wires, which restrain the upper wings. On the 11 the flying wires merged to a single point, while on the 21 they ran parallel to different points on the lower fuselage. The
Nieuport 23 was largely the same as the definitive 17, differing mainly in the use of a different machine gun synchronizer. The gun was offset to starboard, the fuel and oil tank arrangement and the center section rigging were changed to suit. Nieuport 23s were operated by both French and British squadrons alongside Nieuport 17s until their replacement by the later
Nieuport 24, 24bis and
27. The more powerful
Clerget 9B nine-cylinder rotary engine was used by the
Nieuport 17bis, which first appeared late in 1916. The N.17bis had stringers fairing out the fuselage sides compared to the flat sides on the 17. The major user was the British
Royal Naval Air Service, which ordered 32 from Nieuport, 50 more being licence-built by the
Nieuport & General Aircraft Company. Heavier than the preferred Le Rhône, output from the Clerget rotaries quickly fell below their rated power and the performance of the 17bis suffered accordingly. Armament often included a synchronised Vickers gun with the standard over-wing Lewis. Related to the 17bis, the
Nieuport 23bis combined the aerodynamic improvements of the 17bis but reverted to the Le Rhône. Few were built and the Royal Naval Air Service may have been the sole operator. A pair of
triplanes based on the Nieuport 17 were constructed for testing purposes, one for the French and the other for the British. The narrow chord wings were staggered in an unusual manner, placing the middle wing furthest forward and the top wing furthest aft. No subsequent orders came as a result of these tests. Nieuport later trialled the same layout on the Nieuport 17bis, which was tested by the British Royal Flying Corps and Royal Naval Air Service as well, however this also remained a prototype. Several of the experimental
Berliner Helicopters, named after their German-American inventor
Emile Berliner, were manufactured around Nieuport 23 fuselages, including the 1922 and 1923 versions. ==Operational history==