326. An Approach to Environmental Control System Weight Estimation in Advanced Design

Paper

Abstract

This paper was presented at the Twenty-first Annual National Conference of the Society of Aeronautical Weight Engineers at Seattle, Washington, May 14-17, 1962. This paper presents a rational, semi analytical approach to the estimation of the weight of a manned spacecraft environmental control system. The presentation is limited to the orbit phase requirements of an early capability space laboratory. Such a vehicle might be designed for a two to six man crew and for a 100 to 300 n mi earth orbit. These limitations minimize radiation and meteoroid hazards and large weight penalties.
Environmental control system weight is defined as the sum of the functional subsystem weight increments. These increments are identified as the weights of the thermal control subsystem, atmosphere constituent control subsystem, cabin pressure control subsystem, and other miscellaneous subsystems such as waste collection and disposal, water supply, and emergency environmental control.
This paper describes typical system operations and requirements. Typical functional subsystems are defined, their major parameters are discussed, and a step by step procedure for weight analysis is presented. Empirical functions and graphical aids are employed to illustrate how analysis may be simplified and expedited.
A weight summary for the environmental control system of a typical vehicle is presented. Sample weight estimate are outlined to illustrate how the weight summary was derived. A weight tradeoff between a stored gas atmosphere subsystem and an atmosphere regeneration subsystem is discussed and sample results are shown. The method of analysis and the data presented introduce a new phase of weight estimation of great importance in the study and production of manned space vehicles.