Collected Reports of the Panel on Technical Evaluation of NASA's Redesign of the Space Shuttle Solid Rocket Booster (1988) / Chapter Skim
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4 Interim Report #4: June 22, 1987
4 Interim Report #4: June 22, 1987
Pages 25-32
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From page 25... ...
Fletcher Administrator National Aeronautics and Space Administration 400 Maryland Avenue, S.W., Room 7137 Washington, DC 20546 Dear Jim: ~ am pleased to submit herewith the fourth interim report of the National Research Council's Panel for the Technical Evaluation of the Space Shuttle Solid Rocket Booster. The baseline design is essentially complete with only a few choices remaining to be made.
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From page 26... ...
The target date f or del ivering the f irst f ~ ight set to Kennedy Space (enter has changed by about two months, to the middle of December 1987, shill Leaving considerable pressure on the booster testing program. Contingencies.
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From page 27... ...
Contemplation of the next year of scheduled full-scale, fu11-duration firings of demonstration and qualification motors and the tests of full-scale hardware for short duration, reminds us once again of the unique feature of the solid propellant rocket: the flight article itself cannot be test-fired before launch. To compensate for this characteristic, the test program must establish reliability and margins of safety in special ways.
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From page 28... ...
The redesign team currently favors a maximum leak rate of 0.01 standard cubic centimeters per second. The current leak check protocol includes establishing the test pressure in a volume adjacent to the O-ring and watching for a decay of 2 psi within 10 minutes.
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From page 29... ...
Also, in some cases it might be appropriate to measure leak rates using alternative approaches, such as by measuring the buildup of test or tracer gases downstream of a seal rather than by measuring the decay of the test pressure upstream. Nozzle Ablatives The redesign of the internal parts of the nozzle incorporates the carbon-phenolic materials used in the previous design, with changes in the orientation of the carbon fibers in the matrix and improved specification and qualify control of materials.
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From page 30... ...
Means are available for sharing essential proprietary information to assure control while maintaining confidentiality. We recommend that agreements with suppliers be negotiated and implemented to permit stringent engineering control of the materials and processes used in the solid rocket booster consistent with the protection of proprietary interests.
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From page 31... ...
Other critical processes, such as lubrication of the field joint O-rings, are also performed in the Vehicle Assembly Building, emphasizing the need for a higher level of cleanliness in the facility than previously existed. We recommend that the contemplated design and installation of an environmental control system suitable for protecting case segments during assembly be vigorously pursued.
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From page 32... ...
The flight evaluation program should also provide for design, production, evaluation, and introduction of limited modifications of the SRB in response to concerns of engineers regarding reliability of flight performance or problems in manufacturing, inspection, or assembly. The program should provide for preplanned opportunities for changes in order to introduce improvements required as a result of analysis of flight performance data.
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