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Alternatives to Silicon Rubber Thermal Barrier in RSRM Nozzle JointsThiokol Propulsion encountered a situation where gas path can form in the Filler material in joints between the phenolic in the Space Shuttle Reusable Solid Rocket Motor nozzle. An investigation determined that the method for injecting the filler material into the joint created a pressurized pocket of air that forced its way to the surface while the filler was curing. The path that the air took remained open some situations leaving a path for hot gas to get deep into the joint. The condition that created the gas path has been corrected by modifications to the manufacturing process, but a design solution that would reduce processing time is being pursued. A strip of open cell installed deep into the joint, can serve as a barrier to the Filler material. Testing indicates that the foam eliminates the pressure pocket, and does not prevent detection of leakage of the o-ring seals during leak test. Open cell foam does not have thermal resistance capability and mechanical structure, which would be required in the event of a gas path. A replacement to open cell foam is now being considered. Braided carbon fiber rope has the permeability characteristics of foam and it has thermal resistance characteristics as well. Braided carbon fiber rope (BCFR) has been tested in simulated joints in subscale rocket motor. Results of the testing indicate that braided carbon fiber rope can significantly reduce gas temperature by as much es 3000 F in a nozzle joint configuration. BCFR can be installed as a barrier to stop the joint filler material or it can used as the thermal barrier alone.
Document ID
19990064499
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Totman, Peter D.
(Thiokol Propulsion Brigham City, UT United States)
Prince, Andrew
(Thiokol Propulsion Huntsville, AL United States)
Frost, Doug
(Thiokol Propulsion Brigham City, UT United States)
Himebaugh, Paul
(Thiokol Propulsion Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Mechanical Engineering
Report/Patent Number
AIAA Paper 99-2796
Meeting Information
Meeting: Joint Propulsion
Location: Los Angeles, CA
Country: United States
Start Date: June 20, 1999
End Date: June 24, 1999
Sponsors: American Society of Mechanical Engineers, American Society for Electrical Engineers, American Inst. of Aeronautics and Astronautics, Society of Automotive Engineers, Inc.
Distribution Limits
Public
Copyright
Other

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