A Part of the development of the Saturn S-IV/S-IVB stage the Douglas Aircraft Company has pioneered in the development of the cryogenic common bulkhead. The term common bulkhead is derived from the design function of the bulkhead, which is to separate the two cryogenics, liquid hydrogen and liquid oxygen, in a single tank, thereby shortening the stage and eliminating the necessity for two separate bulkheads and the associated interstage structure. The common bulkhead is structurally adequate to withstand both the thermal and the pressure loads from both the hydrogen and the oxygen tanks, and it has sufficient insulation properties to prevent the liquid hydrogen from freezing the liquid oxygen. Another benefit from the common bulkhead is that it permits a reduction in the total length of the vehicle, thereby reducing the bending moments.
