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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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3 Interim Report #3: January 15, 1987
Pages 15-24

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From page 15...
... Fletcher Administrator National Aeronautics & Space Administration 400 Maryland Avenue, S.W., Room 7137 Washington, DC 20546 Dear Jim: January 15, 1987 I am pleased to submit herewith the third interim report of the National Research Council's Panel for the Technical Evaluation of the Redesign of the Space Shuttle Solid Rocket Booster. The redesign effort is currently in transition from a period devoted to creating the so-called baseline design using analytical techniques to one concentrating on testing the concepts and hardware.
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From page 16...
... Only those changes considered mandatory for the next flight are being made. Only if the verification program goes very well can NASA's schedule be met; care must be exercised in the ground-test program to assure that the design is adequately demonstrated.
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From page 17...
... We understand that such a design can be obtained without changing the configuration of the existing forgings, but the first step in this process is to order the appropriate forgings, which has not been done. O Currently, there is no real alternative in the program for the baseline design of the case-to-nozzle joint, which incorporates a large number of new bolls and bold holes, hence complex stress patterns and potential leak paths.
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From page 18...
... We recommend, therefore, that NASA establish and maintain a directed program for continued evaluation and improvement in reliability after flights are resumed, including all of the following: use of flight instrumentation for diagnostics throughout the flight program; continuing evaluation of flight results and recovered hardware; continuing ground testing to understand and, as necessary, improve the hardware promptly; and preplanned block changes to the flight hardware to provide opportunities for incorporating desired improvements. In the long term completely new designs, possibly radica1ly different from the current one, may be preferred.
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From page 19...
... Should a leak occur in the interface, however, the joint has been designed to inhibit further propagation of the high-pressure gases through the O-ring seals. The small joint rotation anticipated with the capture feature, interference metal fit between the clevis leg and capture feature, and three O-rings are configured to provide redundant protection in sealing against various upstream leak scenarios.
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From page 20...
... There are no backups in the program for design of the Jayup of ablative materials in the nozzle. Given the empirical nature of the technology and its unpredicted behavior in past flights, we recommend that, in addition to the planned full scale, full duration tests of the nozzle, the redesign team undertake a series of subscale, long duration firings to evaluate the conceptual basis and materials technology for the redesign of the ablatives.
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From page 21...
... The verif ication program is aimed at determining if the des ign meets requirements, but it should al so have the value of enhancing conf idence that the redesign team understands how the design works. The Presidential Commission concluded that ne ither NASA nor its contractors understood the previous des ign very wet ~ .
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From page 22...
... We believe that the addition of another full scale, full duration firing test stand capable of simulating dynamic loads is a major step forward in that regard. Conditions that should be simulated on the stand include launch loads and the most severe fit ight conditions.
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From page 23...
... Letter to the Honorable James C Fletcher Finally, we are grateful for the received from NASA, Thiokol, and redesign team deserves praise for work.
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Key Terms

  • honorable james
  • test program
  • redesign team
  • solid rocket
  • verif ication

  • capture feature
  • ication program
  • rocket booster
  • shuttle solid
  • adhesive bond

  • design requirements
  • flight program
  • rocket motor
  • additional test
  • duration testing

  • ablative materials
  • test hardware
  • des ign
  • duration firings
  • jes tests

  • technological program
  • gap opening
  • specific design
  • scale test
  • clevis leg

  • field joints
  • pressurized gases
  • space shuttle
  • duration tests
  • ight conditions


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