Saturn S-IVB Cryogenic Weigh System Part III: Environmental Control

In order to provide stage pre-launch thermal environment and to prevent frost formation on the exterior tank surfaces, it was necessary to provide a heated, gaseous nitrogen atmosphere around the stage during cryogenic calibration. Frost formation is undersirable since it would add to the stage tare weight by an unknown amount. Nitrogen conforming to military dryness and cleanliness specifications was chosen for use in contact with the stage skin because of its low moisture content, its inertness with hydrogen or oxygen, its availability, and cost. This paper presents the design concepts of the S-IV and S-IVB stage systems, an appraisal of the S-IV design, and the design changes in the S-IV system as a result of the S-IV experience.