Propellant Behavior during Venting in an Orbiting Saturn S-IVB Stage

Abstract

A Saturn S-IVB Stage, partially filled with liquid hydrogen, was placed in orbit to verify the low gravity performance of certain S-IVB systems [^1[]. A schematic diagram with some significant dimensions of an S-IVB Stage is presented in Fig. 1. Station numbers in the figure signify dimensions in inches from the reference station. The boost phase and an initial S-IVB Stage burn lasted approximately 433 sec. At that time, the stage was placed in a 100-nautical-mile orbit with approximately 19,000 lb of liquid hydrogen and a small quantity of residual oxygen remaining on board. The residual oxygen was vented to provide settling accelerations to the hydrogen tank during the initial 77 sec of orbital coast, and in some of the experiments conducted during the light. Twenty-two seconds before the oxygen ullaging system was closed, the hydrogen continuous Tenting system was activated. Continuous venting was employed during most of the flight. During the continuous venting phase, vented hydrogen vapor was used to provide adequate acceleration to keep the liquid hydrogen settled at the end of the tank opposite the vent. Such a system will be used in the Saturn V/S-IVB Stage to control liquid hydrogen during future orbital coast periods. A separate hydrogen non-propulsive venting system was also available and was used during some of the experiments. The total duration of the experiment was approximately 4 hr.