Brazing and Welding.
It is somewhat amazing that brazing as an essential operation in the making of a joint should still be employed, as it is difficult to imagine anything less suited to the conditions under which aircraft operate. The advantages of a uniform high-grade steel possessing a high ultimate tensile strength are dissipated by the intense heat necessary for the action of brazing, resulting in the strength of the finished joint becoming an extremely problematic quantity, indeed this is rendered the more so by the individuality of the workmen.
Welding properly performed is less objectionable, indeed, its use may be said to be constantly increasing, although it is well to recognize its limitations. It should not be used for parts subject to any great tensile stress, such as the fittings forming the subject of this chapter. The efficiency of any welded joint is hard to determine, as apparent soundness on the surface is no indication of the internal nature of the weld. Regarded from the aphoristic “maximum strength for minimum weight” view point, and taking into account the advantages in this direction which can be obtained by the use of a high-grade steel, brazing and welding are not to be commended.
The operation of soft soldering, requiring only a moderate heat, does not weaken the material to any great extent, and for some items a properly pegged and soldered joint is superior to the two methods of jointing previously described.