W.Green, G.Swanborough The Complete Book of Fighters

NIEUPORT Triplane

   During 1915, Gustave Delage had fitted a Nieuport 10 fuselage with triplane wings of unusual fore-and-aft geometry for experimental purposes, the arrangement being patented on 10 January 1916. Progressive development led, later in 1916, to an even more unorthodox triplane arrangement in which the middle wing, attached to the forward ends of the upper fuselage longerons, was foremost and the upper wing rearmost. Utilising a Nie 17 fuselage, powered by a 110 hp Le Rhone engine and armed with a single synchronised Lewis gun, this triplane was officially tested late in 1916, but was not ordered for the Aviation Militate, and, in consequence, received no official SFA type designation. One example armed with a Vickers gun was acquired for evaluation by the RFC on 26 January 1917, but its flying characteristics were found to be unacceptable. The RNAS also acquired one example in March 1917, this differing in having a Nie 17bis fuselage and a 130 hp Clerget engine. Although allotted to No 11 (Naval) Sqn, it had been discarded by 27 June 1917. The following data relate to the 110 hp version.

Max speed, 110 mph (176 km/h) at 3,000 ft (915 m).
Time to 10,000 ft (3 050 m), 13.6 min.
Empty weight, 919 lb (417 kg).
Loaded weight, 1,386 lb (629 kg).
Span, 26 ft 3 1/2 in (8,01 m).
Length, 19 ft 2 1/2 in (5,85 m).
Height, 7 ft 5 in (2,26m).
Wing area, 143.16 sq ft (13,30 m2).

C.Owers French Warplanes of WWI. Volume 1: Fighters (A Centennial Perspective on Great War Airplanes 43)

The Nieuport Triplanes
  
  In 1915 Gustave Delage created an unusual triplane wing structure that he applied to a Nieuport 10 fuselage. This arrangement was to be subject to patent No. 502.709 by the Nieuport Company on 10 January 1916.
  The disposition of the wings was such that the lower wing was attached to the bottom longerons in the conventional fashion with the middle wing being set to the rear of the other two and being attached to the fuselage upper longerons, with its leading edge approximately over the mid-point of the lower wing. The top wing was in advance of the lower wing with its trailing edge roughly over the leading edge of the bottom wing.
  All wings had only a single spar and were of narrow chord. A triangle of interplane struts braced the three wings and there was frugal cable bracing. The middle wing was longer than the other two and alone had ailerons. The bottom wing was mounted with moderate dihedral and was of the shortest span. Its roots were so cut away to provide downward and forward vision from the rear cockpit that it would seem that the pilot occupied the rear seat. Powered by an 80-hp Le Rhone and bearing the SFA serial N1118 the two-seat triplane was probably never meant to be more than an experimental machine to test the design concept. No results of testing of N1118 have been discovered to date.
  The patent was registered with the British on 29 May 1919, as patent No. 126.995 and stated:

  Sec. Anon. Des Etablissements Nieuport. Jan. 10, 1916, [Convention date] Aerial machine without aerostats; supported by three very narrow planes 1, 2, 3 built up on single spars and connected together by triangular frames 4, 5, 6, one of the planes, preferably the plane 2, being set to the rear of the other two. The plane 3, which may be vertically above the plane 1 or in advance of it, extends over the fuselage, to which it is connected by a pillar member 8.

  The numbers refer to the sketch reproduced on the following pages.
  In 1916 a triplane version of the Nieuport 17.C.1 was produced by Delage. In this he reversed the position of the wings. The top wing was now lying well behind the other two giving the pilot an unobstructed forward and upward view. The middle wing, attached to the upper fuselage longerons, interfered with the pilot's downward view despite curved cut-outs behind the single spar. Ailerons were fitted to the top wing only and the machine looked fragile and decidedly unsafe.
  The first single-seat triplane was powered by a 110-hp Le Rhone 9Ja nine-cylinder rotary engine, and was fitted with the Nieuport cone de penetration. It was armed with a fixed synchronised Lewis gun on the aircraft's centre-line with the gun close to the cockpit to allow for the magazines to be changed by the pilot.
  The triplane underwent its official S.T.Ae trials in late 1916. Speed was quoted as 155 km/hr at 2,000 metres, and the climb to that altitude was 6 min 10 sec. Time to 4,000 metres was 18 min 50 sec, with an estimated ceiling of 5,000 metres. The type was declared obsolete in November 1916.
  An official French document dated 23 December 1916, indicates that the British RFC had learned of the triplane and expressed a desire to obtain an example. The French then agreed to hand over the machine to the British aviation authorities. The late J.M. Bruce noted that at that time the French gave away practically nothing to their Allies, therefore he concluded that their opinion of the triplane was low.
  Brigadier-General Brooke-Popham wrote to the British Aeronautical Supply Depot in Paris on the 4 January 1917, that We should be glad to have this Nieuport Triplane provided it is fitted with a Vickers gun. Please say if this is so, or if you require a gun sent up to fit to it.

  As soon as it is fitted with the gun, one of Messrs Nieuport engines is to be fitted to this machine, which will then be flown to No.2 Aircraft Depot.
  The Nieuport triplane was fitted with a Vickers gun but this proved to be a French Vickers that would fire only French ammunition, and a British pattern gun was telegraphed for on 6 January 1917. Despite this the machine retained its French Vickers gun.
  The triplane, with the SFA serial N1388, was flown to No.2 Aircraft Depot at Candas, from Villacoublay on the 26th by Adjudant de Courcelles, still armed with the French Vickers No.L.233, and taken on charge as RFC A6686. Major-General Trenchard had ordered that he machine be subjected to a climbing test to 10,000 feet and this was undertaken by Lt Miller at Nol.2 A.D. on 2 February 1917. The results were: -
   5,000 ft in 4 min 43 sec
   8,000 ft in 7 min 45 sec
   10,000 ft in 9 min 48 sec

  These figures were slightly better than those for the Nieuport 17 C.1, and Trenchard ordered the triplane flown to the United Kingdom.
  Brooke-Popham wrote to the Director of Aeronautical Equipment at the War Office that the Nieuport triplane was being sent to England by a ferry pilot. It is thought it may be useful as a guide to manufacturers from a point of view of increasing the visibility in machines, especially visibility towards the rear.

  On 2 February A6686 was sent from No.2 A.D. to No.1 A.D. and from there to St Omer the same day. Here it was flown on the 8th and 9th by Lt G.W. Gathergood, being flown to England on the 9th. A6686 was officially tested at Martlesham Heath during March and April 1917, and was subject of Report No. M.90.
  The triplane had the following instruments: Revolution counter; hand pressure pump; aneroid; compass; airspeed indicator; watch; inclinometer and safety belt. A pressure fuel tank of 13.5 gallons was situated behind the pilot with a 9-gallon gravity tank in front of the pilot, as was the 4.5 gallon oil gravity tank.
  The machine was reported to be easy to start and got underway in three minutes. However, longitudinal stability was "not very good; lateral stability was only "fair", and directional was "unstable." Under the heading "Controllability" the opinion was "good" for all three axis. Taxiing was, as one would expect given the wing arrangement, "not very good." The machine was very tail heavy and very "difficult to land well since machine is very apt to slew around on the ground." It took only 70 yards to unstick and 80 yards to pull up with the engine stopped on a calm day.
  Under "Further Remarks" the following comments were made:
  This machine has three planes, the top plane being behind the pilot, giving the pilot a very good view upward and forward; but the view directly forward and downward is not good owing to the middle plane, obscuring the pilot’s vision.
  There are only two single lift wires to each set of planes, one of which is coupled to the chassis struts.
  In the case of a bumpy get off or landing, the wheels are apt to bounce up and hit the lift wire.
  Under "Suggestions for Improvement of Design" it was noted that the Machine was very tail heavy indeed and practically no improvement could be made by altering the rigging to specifications.
  The performance of this machine is considerably below that of modern English fighting scouts.

  The report was signed by Major H.L. Cooper, OC Testing Squadron. The results were reproduced in the Aircraft Data Book which summed up the machine as follows: -
  This machine was found to be directionally unstable, and extremely tail heavy, the latter defect not susceptible to improvement or adjustment. The middle plane obscures the view forward and downward. Landing is difficult, as machine slews round on the ground.

  A copy of Report No. M.90 was sent to Trenchard on 25 April 1917.6 While no copy of his comments has been found to date, it is certain that he would have condemned the type as unacceptable for the RFC. While the precise fate of A6686 is unknown, suggestions have appeared that the RNAS received a Nieuport triplane from the RFC.
  Squadron Commander C.L. Courtney, RNAS, reported on a visit to aircraft factories in November 1916, and reported on the 11th that Nieuport with a 130-hp Clerget engine was "nearing completion in the shops, and was expected to be out for trials in under a week." Why the RNAS and RFC were interested in the Nieuport triplane at this time given that it was declared obsolete by the French in that month. It is probable that they were unaware of these facts.
  The RNAS triplane, N532, was at Martlesham Heath on 7 June. This machine was without an engine and is possible that if N532 was A6686 re-serialled, then the Le Rhone engine could have been removed by the RFC who were always in short supply of this desirable type of engine. Confirmed information on N532 is difficult to find. It apparently had left Martlesham Heath before the Weekly Report for 7 June 1917, was compiled. N532 was reported with No. 11 and No. 10 Squadrons RNAS but confirmation is lacking. It was at Martlesham Heath by April 1917, and was apparently sent to Dunkerque via Dover around 11 May, and was deleted in February 1918.
  The RNAS had another Nieuport triplane, N521. On 10 February 1917, Colonel Regnier, Director de l’Aeronautique Militaire, wrote to the Head of the British Aviation Commission in Paris, Captain Acton, RN, as follows:

  By letter dated January 22nd you asked me to deliver you a 130 hp Clerget Nieuport triplane in exchange for a 130 hp Clerget Sopwith triplane which the Admiralty were kind enough to procure for me.
  I have the honour to inform you that as no arrangements have been made in France for the manufacture of 130-hp Clerget Sopwith triplanes I no longer wish to keep the machine put at my disposal and should be obliged if you would inform me if the Admiralty or the War Office are using it. In this case I will hasten to let you have it back.
  I would add that, apart from this, I will willingly allot to the British Aviation the Nieuport triplane you desire to have.

  Both the RFC and RNAS had expressed an interest in this Nieuport triplane. This was before the report on A6686 was made available. Early in March 1917 the Air Board ruled that the machine was to go to the RNAS at Dunkerque. This version of the triplane was SFA N1946 and it received the RNAS serial N521. A second triplane was ordered as N522, but this was cancelled. This machine was a triplane version of the Nieuport 17bis having both the 130-hp Clerget 9B nine-cylinder engine and faired fuselage of that normally distinguished the 17bis biplane.
  On 5 April, N3184, one of No. 11 Squadron's Nieuport 17bis fighters was flown to Dunkerque for comparative tests against "a 130-h.p. French Nieuport Triplane." The results were that N521 was 3 or 4 knots faster than the Nieuport 17bis at ground level; however, N3184 was fitted with the airscrew appropriate to the 110-hp Clerget at this time. N521 was allotted to No. 11 (Naval) Squadron by 3 May 1917, but its career was short. By 27 June it was lying in the RNAS Depot as unserviceable, it having been there for some time. On this date it was recommended for deletion, its engine being the 130-hp Clerget No.1211. The machine was approved for deletion on 30 June.
  In retrospect, it can be seen that the Nieuport patent was a dead end and did not contribute to the advancement of the Allied fighter during the war.


Nieuport Single-Seat Triplane Specifications
Source 1 2 3
Span 26.3% 26.8 ft 26.8
Length 19.2% 19.1 ft 19.05
Height 7.5 - -
Wheels 700 x 75 - -
Airscrew Levasseur N.3643 Series 484 Levasseur 484 -
Areas in sq ft
   Mainplanes 143 143 143
Weight in lbs
   Armament - - 99
   Vickers gun 35 - -
   Mounting 28 - -
   Deadweight 17 - -
   Crew 180 - 165
   Load - 407 406
   Empty 919 825 825
   Petrol & oil - - 143
   Petrol (22 gall 5 pts) 162 - -
   Oil (4 gall 5 pts) 45 - -
   Tanks &. piping - 39.6 -
   Fuel - 143 -
   Engine - 374 -
   Total 1,386 1,232 1,231
Speed in mph
   Ground level - 105.3 -
   at 3,000 ft 110 - -
   at 6,500 ft 106.0 - -
   at 6,560 ft - 95.75 96.2
   at 9,840 ft - 94.4
   at 10,000 ft 96.5 - -
   at 13,120 ft - 92.5 -
Climb
   to 1,000ft 0.9 mins - -
   to 2,000 ft 1.9 mins - -
   to 3,000 ft 3.0 mins - -
   to 4,000 ft 4.1 mins - -
   to 5,000 ft 5.3 mins - -
   to 6,000 ft 6.7 mins - -
   to 6,500 ft 7.4 mins - -
   to 6,560 ft - 6 min 10 sec 6 min 10 sec
   to 7,000 ft 8.1 mins - -
   to 8,000 ft 9.7 mins - -
   to 9,000 ft 11.5 mins - -
   to 9,840 ft - 11 min 11 min
   to 10,000 ft 13.6 mins - -
   to 11,000 ft 15.9 mins - -
   to 12,000 ft 18.8 mins - -
   to 13,120 ft - 18 min 50 sec
Ceiling in ft 17,000 approx. 16,750 calculated -
Capacities in galls
   Fuel 22.5 17.6 -
   Oil 4.5 2.2 -
Endurance in hours - 2 1/2 2 1/2
Engine 110-hp Le Rhone No.7226 110-hp Le Rhone 110-hp Le Rhone (113 @ 1200)

Notes: Report 90. Speeds were obtained from ASI readings corrected for density and absolute error of the instrument. Probably accurate to 1 mph.
Source:
1) Report M.90 - Summary of Results. TNA AIR1/192/204/5/2599. These results were included in the 10th Weekly Report of the Controller, Technical Dept for the W/E 25.04.1917. TNA AIR1/2094/207/12/10.
2) S.T.Ae. The chart has the Section Technique de L’Aeronautique heading but all details are in English. It is assumed these charts were used by the British who converted the metric results to Imperial measurements with always the chance that errors could creep in. TNA AIR1/708/27/11/459.
3) Hand written chart from TNA AIR1/708/27/11/455 in RAF Museum J.M. Bruce Collection Box 21. Note to Nieuport Triplane column states it was obsolete in November 1916.