Last week’s test of a 5-segment SRB produced data, as reported by Florida Today, that showed thrust oscillation (TO) due to acoustic vibrations 8-10 times less than that estimated in the models for a 5-segment SRB. In fact, the resulting thrust oscillation due to acoustic vibrations in the test were small enough that there is now talk that thrust oscillation mitigation techniques may not be required for Ares I, removing from the table one of biggest technical challenges facing that program.
Until last week, the concerns about TO and its affect on Orion and her crew are based on models, not data. Assuming that the models used to predict TO on Ares I were retuned to output results for the test article, that the models’ expected and the actual test results differed so significantly indicates that the models are far off and in need of a serious rework. That the actual levels of TO experienced in last week’s test were 8-10 times less than predicted means, for all practical purposes, the models that predicted large enough trust oscillation on Ares I to possibly damage the Orion spacecraft and her crew are less than useless, they are misleading, which is worse.
These test results also represent a big challenge for the Human Space Flight Review Committee. If in the final analysis the data shows that thrust oscillation due to acoustic vibration, the chief technical challenged faced so far by Ares I, is less than of a challenge than it once was, the conclusions of the HSFR Committee concerning the Ares I launcher will have to be reassessed in line with that data.
In short, last week’s SRB test may have saved the Ares I program. I can’t think of another time when a test has produced such a big change in a multi-billion dollar program while also forcing the modeling community to fully reassess its techniques.