Monday, August 01, 2005

Getting the Problem Fixed

New NASA administrator Michael Griffin has promised that the problems with the shuttle's external tank will be fixed before another vehicle flies. Happily, this may not take long, as the PAL ramps have been looked at before and some ideas for fixes already advanced. In the April 26, 2004 version of NASA's own RTF Implementation report:

PAL Ramps Status

Because the PAL ramps (figure 3.2-1-12) have an excellent flight history, NASA’s baseline approach for RTF is to develop sufficient certification data to accept the debris risk of the existing design. This will be accomplished by evaluating the available verification data and augmenting it with additional tests, analyses, and/or inspections. This will include dissecting several existing PAL ramps to understand the void sizes produced by the existing PAL ramp TPS process. If NASA is unable to obtain sufficient data to recertify the existing PAL ramps, the Agency will remove the PAL ramp and replace it with an improved-process manual spray application. In addition, an automated PAL ramp spray is being evaluated for Phase 2 activities.

Concept design activities are in work to eliminate the PAL ramps as part of the Phase 2 activity. Redesign options include eliminating the PAL ramps altogether, implementing smaller mini-ramps, or incorporating a cable tray aero block fence on either the leading or trailing edge of the tray. NASA conducted subscale wind tunnel testing of the candidates that indicated a good potential for eliminating the foam PAL ramps. Additional wind tunnel tests are planned for this spring and summer.

In other words, they have some grip on this problem and presumably the Tiger team Griffin has put in charge will be able to quickly implement a solution. One thing's for sure, I doubt we'll see any more pre-Columbia ETs, if any more are knocking around in the system, fly.

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