Fig. 36-a. Details of Albatros Veneer Fuselage Construction.
In some machines the interplane stay wires are attached to a lug formed from the attachment plate, but we do not consider that this construction is as good as the type in which the wire is attached directly to the wing spar pin. While the former may be easier to assemble, the attachment of the wire to the pin eliminates any eccentricity, or bending moment, due to the pull of the interplane stay. The attachment in the L. W. F. insures against any eccentricity in the stay attachment, and at the same time makes the assembly and dismounting a very simple matter.
Fig. 37. Wing Connection to Fuselage.
Chassis Member Attachment. The attachment of the chassis struts generally involves some difficulty as these members usually intersect the line of the longerons at a very awkward angle. If the wing attachment is near the same point, as it generally is, the detail is made doubly difficult. The chassis must be pin connected as in the case of the wing joint so that the chassis members can be easily and quickly removed. A detail of a chassis to body connection is shown by Fig. 39. In this figure (L) is the lower longeron, (S) is the vertical fuselage strut, and (C) is one of the chassis members. The upper end of the chassis member is enveloped in a sheet steel ferrule (D) which is bolted in place, and which is provided with a clevis at its upper end for the attachment pin (P).
A plate (E) is bolted to the fuselage strut (S) and is passed around the lower longeron (L), a hinge joint (H) being provided for attachment to the chassis ferrule through the pin (P). Ears or lugs are left at (G-G) for the attachment of the fuselage stays (B-B). On the inner side of the plate (E) are attachment lugs for the horizontal strut (H). It will be noted that the plate (E) is well provided with lightening holes so that the weight can be kept down to a minimum. The pin is tapered at the end, and is provided with cotter pin holes. The fitting in general is small, and does not produce any great degree of head resistance, the small part exposed being of good streamline form.
Fig. 38x. Wing Connection of the Albatros Reconnaissance Biplane. Fig. 38y. Wing Attachment of Albatros Fighter with Pin Joint. Fig. 38z. Wing Connection of London and Provincial Biplane.
Great care should be taken in brazing or welding these fittings, since the heat changes the structure of the metal and greatly reduces its strength. The brazing temperature varies from 1,500 to 1,700 degrees, a point well above the tempering heat of steel. Attempts have been made to heat treat the metal after the brazing operation, but with very little success, owing to the fact that the heat treating temperature is generally at or above the melting point of the brazing spelter, hence is likely to cause holes and openings in the brazed joints. With acetylene welded joints the parts can, and should be, heat treated after the welding. While this is an apparent advantage of acetylene welding, all parts cannot be successfully handled in this manner. The welding torch can only join edges, while the brazing spelter can be applied over almost any area of surface. Welding is very successful in joining thin steel tubes while in many fittings made of sheet metal, brazing is the only feasible operation.