Flight, January 1923

THE PARIS AERO SHOW 1922

HANRIOT ET CIE., NEUILLY-SUR-SEINE

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   The second machine shown on the Hanriot stand is an all-metal chaser, single-seater, with 260 h.p. Salmson engine, type Cu. Z. 9. The machine is shown in skeleton, so that the detail construction can be thoroughly inspected.
   With the exception of a few fittings of steel, the Hanriot "H.26" is built entirely of Duralumin, this metal being used mostly in the form of channel-sections.
   The fuselage is constructed of four main channel-section Duralumin longerons, formed into a Warren girder by channel-section struts which entirely triangulate the structure. The longerons have their open sides facing towards one another, as regards the side panels. Thus, the struts of the sides fit into the channels top and bottom, while the horizontal struts are attached to the longerons by gusset plates and rivets. The main structure is of rectangular section, turned into a streamline shape by light channel-section stringers and formers, built on to the main structure as indicated in our sketches.
   Also built entirely of Duralumin are the wings, of which the lower is quite small, the machine belonging to the "sesquiplan" type, now so popular in France. The wings are remarkable for the fact that they have but a single spar, although tubular leading edges and false rear spars assist materially in stiffening the structure. Light channel-section stringers and diagonal members serve to brace the wing structure, there being no internal drag bracing of the usual type. It appears probable that this form of bracing has been chosen in order to attain, at the same time as providing the drag bracing, a certain amount of stiffening against torsion, the single spars being probably somewhat inadequate in this respect.
   In the case of the lower wing, the single main spar is in the form of a Duralumin tube of rectangular section, with, of course, the corners rounded-off. The tubular leading edge is attached to the long strut of the undercarriage and to the lower longerons, while the false rear spar, also a Duralumin tube, is supported from the lower longerons. All the main attachments of these spars to chassis or longerons are in the form of sheet steel fittings, some of which are of somewhat complicated shape, but all of which appear extremely well-made, and, like the rest of the machine, beautifully finished. The lower main spar is attached, also by a sheet steel fitting, to lower longeron and the junction of two of the undercarriage struts with the fuselage.
   The upper plane, which is of much larger span and chord than the lower, is of similar construction, with the exception that the main spar, placed fairly far aft in the Schoukowsky aerofoil, is not a one-piece Duralumin tube, but is built-up of sides stamped out to form an N-girder, riveted to flat top and bottom flanges. In stamping-out the lightening pieces of the spar sides, these are given a slight curvature, so that the "legs" of each "N" are in section like a very shallow trough. Each side of a spar appears to be in one piece, stamped out of a single strip of Duralumin.
   The ribs of both top and bottom plane are built up in the form of a Warren girder, the material used being light Duralumin of channel-section. Ailerons are fitted to top plane only, and are operated by a system of tubes, chains and sprockets. The leading edge of the aileron is a rectangular section Duralumin tube.
   The wing bracing of the Hanriot "H.26" is unusual, inasmuch as it does not incorporate any struts, although the wings are not entirely cantilever beams on account of a single lift wire, running from the rear strut of the undercarriage to the top plane, passing en route to a fitting over the lower plane main spar. Both this fitting and the corresponding one on the top plane are of sheet metal: It is stated that the factor of safety on the wings is 12, loaded in the normal way. As regards torsional stresses and down loads such as may occur during a nose drive, the factor of safety may be considerably smaller, although this form of construction, with but single spars, has been used on the Hanriot "H.D.15" with, so far as we are aware, good results. That machine had, however, interplane struts to assist in resisting torsional stresses. To a certain extent, the fact that leading edge and false rear spar are secured to the fuselage should help matters, although, in view of the relatively small width of the fuselage, these points lie fairly close together and a long way from the wing tips. In pure bending, there is little doubt that the wings are amply strong, and it appears probable that the figure 12, given as the factor of safety, relates to pure bending only.
   The undercarriage, also a Duralumin structure, is of somewhat unusual design, inasmuch as there is a set of struts forming a letter N in side view, linking the lower portion of the undercarriage to the fuselage. These "N's," however, are reinforced by a single strut on each side, running from the shock-absorber attachments to the main spar of the top plane, at the point where this is attached to the fuselage. It will thus be seen that the long single struts do not lie in the same plane as that of the "N" struts, and a form of triangulation, as seen in front view, is obtained. This accounts for the fact that there is no transverse wire bracing in the undercarriage. A small wing section encloses the transverse tubes and axle of the chassis. The axle does not run right through, but is divided, a short length of fixed tube resting inside the fairing, with two short axles hinged to its ends. From the axle hinges wires run to the fuselage fitting on the lower longeron, at the point where the lower plane front spar is attached.
   Whatever one may think of the design of the Hanriot "H.26," especially as regards its wing structure, the workmanship is excellent, and the finish, made complete by some form of spraying with metal, above even the high average French standard.
   The main characteristics of the Hanriot "H.26" are :- Length o.a., 7-35 ms. (24 ft. 2 ins.); span, 9 ms. (29 ft. 6 ins.); height, 2-5 ms. (8 ft. 3 ins.); wing area, 18 sq. ms. (194 sq. ft.); weight, empty, 820 kgs. (1,800 lbs.); weight of fuel (3 hrs.), 180 kgs. (396 lbs.); useful load, 80 kgs. (176 lbs.); total loaded weight, 1,080 kgs. (2,372 lbs.); power loading, 9-14 lb./h.p.; wing loading, 12-25 lb./sq. ft. Estimated performance: Maximum speed near ground, 260 kms. (161 miles) per hour; speed at 2,000 ms. 255 kms. (158 miles) per hour; ceiling, 8,500 ms. (28,000 ft.).