Hotfire testing of a SSME HPOTP with an annular hydrostatic bearing

A new fluid film bearing package has been tested in the Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbopump (HPOTP). This fluid film element functions as both the pump end bearing and the preburner pump rear wear ring seal. Most importantly, it replaces a duplex ball bearing package which has been the primary life limiting component in the turbopump. The design and predicted performance of the turbopump are reviewed. Results are presented for measured pump and bearing performance during testing on the NASA Technology Test Bed (TTB) Engine located at MSFC. The most significant results were obtained from proximity probes located in the bearing bore which revealed large subsynchronous precession at ten percent of shaft speed during engine start which subsided prior to mainstage power levels and reappeared during engine shutdown at equivalent power levels below 65% of nominal. This phenomenon has been attributed to rotating stall in the diffuser. The proximity probes also revealed the location of the bearing in the bore for different operating speeds. Pump vibration characteristics were improved as compared to pumps tested with ball bearings. After seven starts and more than 700 seconds of testing, the pump showed no signs of performance degradation

RS-25 for the NASA Crew Launch Vehicle: The Evolution of SSME for Space Exploration

As a first step towards the fulfillment of the National Vision for Space Exploration, NASA has begun development of the Crew Launch Vehicle (CLV). The CLV will act, in conjunction with the Crew Exploration Vehicle, as the next generation human launch system to first support missions to the International Space Station (ISS), then later to support the lunar return missions, and then after that to exploration missions to Mars and beyond. The CLV is a two-stage launch vehicle with the first stage based upon the Space Shuttle solid rocket booster. The newly designed, expendable second stage is powered by a single RS-25 liquid hydrogen/liquid oxygen rocket engine. The RS-25 is essentially the Space Shuttle Main Engine (SSME) evolved for a new mission, new environments, and new conditions. The CLV Upper-Stage Engine (USE) office has been established to develop the RS-25 in support of the CLV Project. This paper presents an outline and discussion of the risks associated with this endeavor of transforming the SSME into the upper-stage, altitude-start RS-25 and the plans being undertaken to understand and mitigate these risks. In addition, to meet the long-term requirements of the CLV launch manifest, it will be necessary to redevelop the RS-25, with its long history as the reusable SSME for the Space Shuttle Program, as an expendable engine. While the first flights of CLV will be using heritage SSME hardware, beyond that a new version of RS-25 as an expendable engine is being pursued by the CLV USE element. The goals of this work include the need to make the hardware more producible while maintaining the inherent and inherited reliability of the basic design. This paper will also discuss the risks and present the plans for developing both this next generation version of the RS-25 and for developing the manufacturing capacity necessary to support the CLV Project

Fabrication and Testing of Ceramic Matrix Composite Propulsion Components

A viewgraph presentation outlines NASA's goals for the Second and Third Generation Reusable Launch Vehicles, placing emphasis on improving safety and decreasing the cost of transporting payloads to orbit. The use of ceramic matrix composite (CMC) technology is discussed. The development of CMC components, such as the Simplex CMC Blisk, cooled CMC nozzle ramps, cooled CMC thrust chambers, and CMC gas generators, are described, including challenges, test results, and likely future developments

Data from: Revised Airlie House consensus guidelines for design and implementation of ALS clinical trials

Objective: To revise the 1999 Airlie House consensus guidelines for the design and implementation of preclinical therapeutic studies and clinical trials in amyotrophic lateral sclerosis (ALS). Methods: A consensus committee comprising 140 key members of the international ALS community (ALS researchers, clinicians, patient representatives, research funding representatives, industry and regulatory agencies) addressed nine areas of need within ALS research: 1. Pre-clinical studies; 2. Biological and phenotypic heterogeneity; 3. Outcome measures; 4. Disease-modifying and symptomatic interventions; 5. Recruitment and retention; 6. Biomarkers; 7. Clinical trial phases; 8. Beyond traditional trial designs; and 9. Statistical considerations. Assigned to one of eight sections, committee members generated a draft set of recommendations based on a “background” of developing a (pre)clinical question and a “rationale” outlining the evidence and expert opinion. Following a two-day, face-to-face workshop at the Airlie House Conference Center, a modified Delphi process was used to develop draft consensus guidelines, which were subsequently reviewed and modified based on comments from the public. Statistical experts drafted a separate document of statistical considerations (section 9). Results: In this paper we summarize 112 recommendations and their associated backgrounds and rationales. The full list of recommendations on all main topics as well as on statistical considerations are available (Appendices e-3 and e-4). The authors prioritized 15 recommendations with the greatest potential to improve ALS clinical research. Conclusion: The revised Airlie House ALS Clinical Trials Consensus Guidelines should serve to improve clinical trial design and accelerate the development of effective treatments for patients with ALS

Appendix e-4 Full ALS Clinical Trial Guidelines

Appendix e-4 Full ALS Clinical Trial Guideline

Appendix e-5 Statistical Considerations

Appendix e-5 Statistical Consideration

Revised Airlie House consensus guidelines for design and implementation of ALS clinical trials.

ObjectiveTo revise the 1999 Airlie House consensus guidelines for the design and implementation of preclinical therapeutic studies and clinical trials in amyotrophic lateral sclerosis (ALS).MethodsA consensus committee comprising 140 key members of the international ALS community (ALS researchers, clinicians, patient representatives, research funding representatives, industry, and regulatory agencies) addressed 9 areas of need within ALS research: (1) preclinical studies; (2) biological and phenotypic heterogeneity; (3) outcome measures; (4) disease-modifying and symptomatic interventions; (5) recruitment and retention; (6) biomarkers; (7) clinical trial phases; (8) beyond traditional trial designs; and (9) statistical considerations. Assigned to 1 of 8 sections, committee members generated a draft set of guidelines based on a "background" of developing a (pre)clinical question and a "rationale" outlining the evidence and expert opinion. Following a 2-day, face-to-face workshop at the Airlie House Conference Center, a modified Delphi process was used to develop draft consensus research guidelines, which were subsequently reviewed and modified based on comments from the public. Statistical experts drafted a separate document of statistical considerations (section 9).ResultsIn this report, we summarize 112 guidelines and their associated backgrounds and rationales. The full list of guidelines, the statistical considerations, and a glossary of terms can be found in data available from Dryad (appendices e-3-e-5, doi.org/10.5061/dryad.32q9q5d). The authors prioritized 15 guidelines with the greatest potential to improve ALS clinical research.ConclusionThe revised Airlie House ALS Clinical Trials Consensus Guidelines should serve to improve clinical trial design and accelerate the development of effective treatments for patients with ALS

Appendix e-3 Glossary of Terms

Appendix e-3 Glossary of Term