SRB Acoustic and Plume Analysis of Ares I-X Flight Test On The Pad B Fixed Service Structure

Paper number

IAC-10.C4.2.5

Author

Mr. Roger X. Lenard, LPS, United States

Year

2010

Abstract

The Space Transportation System exhibits a very predictable initial launch ascent trajectory, which has been well-characterized for the past thirty years.  The acoustic and plume impingement signature on the Fixed Service Structure (FSS) is well known.  However, Ares I-X as a single stick launch system exhibits a remarkably greater potential range of motions than does the STS.  Inn addition to a larger range of motion available to the Ares I-X system, the authors discovered a new acoustic mode that couples with the FSS in a complex and resonant fashion.  Further, stochastic errors in nozzle position, thrust and unique new bending moments, some not evident on the STS and others that offset each other on the STS must be factored into the ascent trajectory and resultant loads and environments on the fixed structures.

Discovery of the stochastic errors occurred late in the program and active trajectory compensation was required to limit loads.  Analysis of the acoustic signature led to the discovery of a heretofore unaccounted-for external cavity mode. Each of these discoveries and determinations will have a profound impact on Ares I design ground support equipment design, particularly if a five segment or five – ½ segment solid is used.  The authors discuss how the acoustic and plume impingement analysis was performed and the resulting ensemble of effects on the fixed service structure, and the necessary mitigating effects that were imposed in order to enable a hazard-free launch. The authors discuss the impact of those mitigating features within the flight test and detail some unexpected results. The authors will also make some prediction for the environments that might be encountered with the Ares I solid rocket motor.

Abstract document

IAC-10.C4.2.5.brief.pdf

Manuscript document

IAC-10.C4.2.5.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.