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A life support system (LSS) is usually defined as a system that provides elements necessary for maintaining human life and health in the state required for performing a prescribed mission. The LSS, depending upon specific design requirements, will provide pressure, temperature, and composition of local atmosphere, food, and water. It may or may not collect, dispose, or reprocess wastes such as carbon dioxide, water vapor, urine, and feces. It can be seen from the preceding definition that LSS requirements may differ widely, depending on the mission specified, such as operation in Earth orbit or lunar mission. In all cases the time of operation is an important design factor. An LSS is sometimes briefly defined as a system providing atmospheric control and water, waste, and thermal management.

The purpose of this section is to provide methods and a set of convenient working charts to estimate penalty values in terms of take-off fuel weight for any given airplane mission. The curves are for a range of specific fuel consumption (SFC) and lift/drag ratio (L/D) compatible with the jet engines and supersonic aircraft currently being developed. A typical example showing use of the charts for an air conditioning system is given. Evaluation of the penalty imposed on aircraft performance characteristics by the installation of an air conditioning system is important for two reasons: 1 It provides a common denominator for comparing systems in the preliminary design stage, thus aiding in the choice of system to be used. 2 It aids in pinpointing portions of existing systems where design improvements can be most readily achieved.

The purpose of this section is to provide methods and a set of convenient working charts to estimate penalty values in terms of take-off fuel weight for any given airplane mission. The curves are for a range of specific fuel consumption (SFC) and lift/drag ratio (L/D) compatible with the jet engines and supersonic aircraft currently being developed. A typical example showing use of the charts for an air conditioning system is given. Evaluation of the penalty imposed on aircraft performance characteristics by the installation of an air conditioning system is important for two reasons: 1 It provides a common denominator for comparing systems in the preliminary design stage, thus aiding in the choice of system to be used. 2 It aids in pinpointing portions of existing systems where design improvements can be most readily achieved.

Recommendations of this ARP refer specifically to the application of closed cycle vapor cycle refrigeration systems as a source of cooling in an aircraft air conditioning system. General recommendations for an air conditioning system which may include a vapor cycle system as a cooling source are included in ARP 85, Air Conditioning Equipment, General Requirements for Subsonic Airplanes, ARP 292, Air Conditioning, Helicopters, General Requirements For, and AIR 806, Air Conditioning Design Information for Cargo and High Density Passenger Transport Airplanes, and are not included herein.

Recommendations of this ARP refer specifically to the application of closed cycle vapor cycle refrigeration systems as a source of cooling in an aircraft air conditioning system. General recommendations for an air conditioning system which may include a vapor cycle system as a cooling source are included in ARP 85, Air Conditioning Equipment, General Requirements for Subsonic Airplanes, ARP 292, Air Conditioning, Helicopters, General Requirements For, and AIR 806, Air Conditioning Design Information for Cargo and High Density Passenger Transport Airplanes, and are not included herein.

Recommendations of this ARP refer specifically to the application of closed cycle vapor cycle refrigeration systems as a source of cooling in an aircraft air conditioning system. General recommendations for an air conditioning system which may include a vapor cycle system as a cooling source are included in ARP85, Air Conditioning Equipment, General Requirements for Subsonic Airplanes, ARP292, Air Conditioning, Helicopters, General Requirements For, and AIR806, Air Conditioning Design Information for Cargo and High Density Passenger Transport Airplanes, and are not included herein. Vapor cycle refrigeration system design recommendations are presented in this ARP in the following general areas: a SYSTEM Design Recommendations: (See Section 3) b COMPONENT Design Recommendations: (See Section 4) c Desirable Design Features: (See Section 5)

This Recommended Practice is intended to outline the design, installation, testing, and field maintenance criteria for a high temperature metal pneumatic duct system, for use as a guide in the aircraft industry. These recommendations are to be considered as currently applicable and necessarily subject to revision from time to time, as a result of the rapid development of the industry.

This Recommended Practice is intended to outline the design, installation, testing, and field maintenance criteria for a high temperature metal pneumatic duct system, for use as a guide in the aircraft industry. These recommendations are to be considered as currently applicable and necessarily subject to revision from time to time, as a result of the rapid development of the industry.

This report provides data and general analysis methods for calculation of internal and external, pressurized and unpressurized airplane compartment pressures during rapid discharge of cabin pressure. References to the applicable current FAA and EASA rules and advisory material are provided. While rules and interpretations can be expected to evolve, numerous airplanes have been approved under current and past rules that will have a continuing need for analysis of production and field modifications, alterations and repairs. The data and basic principles provided by this report are adaptable to any compartment decompression analysis requirement.

The fluid flow treated in this section is isothermal, subsonic, and incompressible. The effects of heat addition, work on the fluid, variation in sonic velocity, and changes in elevation are neglected. An incompressible fluid is one in which a change in pressure causes no resulting change in fluid density. The assumption that liquids are incompressible introduces no appreciable error in calculations, but the assumption that a gas is incompressible introduces an error of a magnitude that is dependent on the fluid velocity and on the loss coefficient of the particular duct section or piece of equipment. Fig. 1A-1 shows the error in pressure drop resulting from assuming that air is incompressible. With reasonably small loss coefficients and the accuracy that is usually required in most calculations, compressible fluids may be treated as incompressible for velocities less than Mach 0.2.

The fluid flow treated in this section is isothermal, subsonic, and incompressible. The effects of heat addition, work on the fluid, variation in sonic velocity, and changes in elevation are neglected. An incompressible fluid is one in which a change in pressure causes no resulting change in fluid density. The assumption that liquids are incompressible introduces no appreciable error in calculations, but the assumption that a gas is incompressible introduces an error of a magnitude that is dependent on the fluid velocity and on the loss coefficient of the particular duct section or piece of equipment. Fig. 1A-1 shows the error in pressure drop resulting from assuming that air is incompressible. With reasonably small loss coefficients and the accuracy that is usually required in most calculations, compressible fluids may be treated as incompressible for velocities less than Mach 0.2.