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Operationally Efficient Propulsion System Study (OEPSS) Data Book
The following is an excerpt from the Operationally Efficient Propulsion System Study (OEPSS), Data Book, Volume III - Operations Technology, prepared for KSC under contract NAS10-11568. This book was prepared by John O. Vilja. Rocketdyne Study Managers were G.S. Wong and Glenn S. Waldrop. The NASA, KSC Study Manager was Russell E. Rhodes. This excerpt is placed here as relevant to our next generation RLV effort. For further information on the complete study contact Russell E. Rhodes, NASA KSC or see the "Videos & Reports" ... more>

Introduction

This data book describes the specific technology identified during the Operationally Efficient Propulsion System Study (OEPSS), which addresses the operations concerns identified during the study. The OEPSS study examined launch operations of all currently active American launch systems to determine which elements of the system have the greatest impact on operability in terms of cost, schedule, and reliability.

This launch site operations survey resulted in a list of 25 major operations concerns or problems that will require improvement in future launch system designs. This list is presented below and reflects the order of criticality as assessed by consensus of launch site personnel. Detailed descriptions of each of these operations concerns can be found in the OEPSS Data Book Volume II, Ground Operations Problems.

  1. Closed aft compartments
  2. Hydraulic system (valve actuators and TVC)
  3. Ocean recovery/refurbishment
  4. Multiple propellants
  5. Hypergolic propellants (safety)
  6. Accessibility
  7. Sophisticated heat shielding
  8. Excessive components/subsystems
  9. Lack hardware integration
  10. Separate OMS/RCS
  11. Pneumatic system (valve actuators)
  12. Gimbal system
  13. High maintenance turbopumps
  14. Ordnance operations
  15. Retractable T-0 umbilical carrier plates
  16. Pressurization system
  17. Inert gas purge
  18. Excessive interfaces
  19. Helium spin start
  20. Conditioning/geysering (LOX tank forward)
  21. Preconditioning system
  22. Expensive commodity usage - helium
  23. Lack hardware commonality
  24. Propellant contamination
  25. Side-mounted booster vehicles (multiple stage propulsion systems)

The operations concerns that have been identified provided a basis for carefully examining the elements of the propulsion system that need to be addressed using existing technology and which will require additional technology development. It was found that many of the operations concerns can be addressed by existing technology, such as integrating and consolidating subsystems; however, further technology development is required to eliminate complex subsystems. An example of such technology would be the integration of the complex, multiple helium bottles and regulation systems into a single helium vessel with primary and backup regulation systems. This integration would simplify the launch system immensely; however, it would not address the capability to remove helium completely from the launch system altogether by designing-out the engine purge requirement.

The technology listed in this data book are those identified by the OEPSS team, which would begin removing operations-intensive subsystems from future launch vehicles. These significant operations enhancing technologies are listed below.

  1. No purge pump seals
  2. No-purge combustion chamber
  3. Oxidizer-rich turbine, LOX turbopump
  4. Hermetically sealed inert engine (prelaunch)
  5. Combined hydrogen systems (MPS,OMS,RCS,ECLSS, fuel cell)
  6. Flash boiling tank pressurization
  7. Low-NPSH pumps
  8. Large flow range pumps
  9. Differential throttling
  10. Electric motor actuator (EMA)
  11. No leakage mechanical joints
  12. Automated self-diagnostic condition monitoring system
  13. Integrated propulsion module concept
  14. Antigeyser, LOX tank aft propulsion concept
  15. Rocket engine air-augmented afterburning concept

This data book describes for each technology (a) the operational objective, (b) the operations concerns specifically addressed, (c) a recommended development approach for new technology and those already under development, and (d) and approximate schedule for it's development. Section 2.0 provides some examples of how technology could benefit launch operations.

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