30 initially this can cause leakage of air and can become sufficiently serious as to eventually require replacement of the assembly 24 transition constructions of the invention which correct all of these deficiencies will be described now a first support assembly 62 comprises four nested 30 mil diaphragm plates 64 66 68 and 70 which are structurally strong and provide effective insulation between the forward header 28 and a second support assembly 72 which will be described below the foremost diaphragm plate 64 is suitably welded to the forward header 28 and each succeeding diaphragm plate is welded to its adjacent diaphragm plates sixteen mil thick insulation plates 74 are sandwiched between the diaphragm plates 64 66 68 70 the insulation plates 74 may comprise mica for example and serve to prevent the diaphragm plates from collapsing due to preload and also act as effective thermal insulators most of the temperature difference and the induced thermal stresses between the forward header 28 and the assembly 24 are confined to the first support assembly 62 during the whole operating regime of the engine it is estimated that each diaphragm plate and insulation plate sandwich can generally accommodate a temperature difference of 120 u00b0 f between itself and its neighbor without reaching yield stress levels in this manner the temperature gradient is held to a magnitude acceptable to the more flexible but less strong components of the second support assembly 72 thus overall the temperature is gradually stepped up or down between the forward header 28 and the assembly 24 permitting all the disks in the manifold assembly to operate under stresses well.