Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) AFRL/VSE Air Force Research Laboratory Space Vehicles Directorate SPONSOR/MONITOR'S REPORT3550 Aberdeen Ave SE NUMBER(S)Kirtland AFB, NM 87117-5776 AFRL-VS-PS-TP-2006-1051 DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. (Clearance #VS06-0220) SUPPLEMENTARY NOTESPublished in the 42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Sacramento, CA 9-12 July 06Government Purpose Rights ABSTRACTOver the recent years, Microcosm has been pursuing the development of a Tridyne-based pressurization system and its implementation in the Scorpius family of launch vehicles to obtain substantial gain in payload to orbit. This technology program was initiated with an IR&D program and matured with contracts from the National Reconnaissance Office (NRO), and the Air Force Research Laboratory (AFRL). The Tridyne pressurization system functions by mixing small amounts of hydrogen and oxygen with the pressurant gas (typically helium). When the mixture is passed through a catalyst bed, the hydrogen and oxygen react to produce heat. The result is hot pressurant gas, with a small amount of water vapor remaining from the combustion process. The implementation scheme developed for the Scorpius family of launch vehicles involves returning some of the heat to the Tridyne mixture in the pressurant tank by means of an internal heat exchanger. This offsets the expansion cooling such that the temperature of the pressurant actually rises as the pressurant is used. The remaining energy is used to elevate the temperature of the gas delivered to the propellant tanks to near the maximum allowable operating temperature of the downstream components (typically about 200 to 250 deg F) such as the regulator and the composite over-wrapped propellant tanks. The result of heating the helium in this way was shown to reduce the mass and volume of required helium and the associated tankage by nearly 50%, resulting in substantial payload gain. The technology qualification program verified perfor...