DESCRIPTION AND EVALUATION OF ENVIRONMENTAL CONTROL AND CRYOGENIC SUPPLY SUBSYSTEMS FOR X-20 (DYNA-SOAR)

The X-20A (Dyna-Soar) environmental control subsystem transported heat from the pilot's compartment, equipment compartment, and secondary power subsystem heat loads by a water-glycol mixture to the central cryogenic hydrogen heat sink. The warmed hydrogen was subsequently used as fuel for accessory power units (APU) or to maintain constant pressure in the supercritical hydrogen supply tank. Super-critical stored oxygen was furnished to the APU for combustion and also was diluted by nitrgen and supplied to the open-type pilot's atmosphere control subsystem. Pure nitrogen was used to maintain pressure in the separate, uninhabited equipment compartment. Aerodynamic heat was blocked from entering the three compartments by a passive water-wall subsystem. Gelled water was held in sponges and secured between appropriate amounts of insulation until aerodynamic heat penetrated to the gel and boiled away the water. The environmental control and cryogenic supply sub-systems are described and evaluated up to the time the X-20 was terminated. (Author)