3701. Mass Properties in Support of Class Analysis (a.k.a. MP End of Days)


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Ricardo Roy: 3701. Mass Properties in Support of Class Analysis (a.k.a. MP End of Days). 2018.



You receive the following Program Office Request: In lieu of mission specific analysis, it is dictated to you that Class Analysis be instituted to lower overall program cost. There may be other methods to address this request but this paper addresses one process that provided mass properties in support of program ‘Class Analysis’. To get started, a definition of Class Analysis is prudent. Class Analysis is any single study that incorporates all conceived configurations of a vehicle from mass properties (MP) perspective and the MP uncertainties associated with them.The main purpose is to provide a range of mass properties with a high likelihood that the current and future fleet elements will not exceed them.This process is based on simulated aerospace hardware data and does not reflect any specific line of vehicles. Additionally, the same process may be applied to non-aerospace production programs. All that is required is a good history of launch vehicle segments along with mass properties and uncertainties for each segment. Ten (10) years of history is ideal, but a smaller term is acceptable knowing that risk may be incurred. A segment is defined as any portion of the launch vehicle that may get jettisoned during the launch cycle. A robust verification process to validate that the assumed variables are still compliant is also a must.This analysis will not only be performed by the mass properties group but also by all the downstream users (Guidance, Flight Mechanics, Separation, Structures, Ground Ops …etc.). Mass Properties is the initial cog in a long string of analysis that will be scrutinized. This being said, the mass properties group must not operate in a vacuum, but coordinate with these downstream users to access the effects of your assumptions. All data units herein will be presented as: Mass (M) = pounds-mass (lbm); Center of Mass (CM) = inches (in) or stations; and Moment and Product of Inertias (MOI and POI) = slug-foot2 (sl-ft2). Inertias will be in respect to the CM. A positive integral definition will be used for POI.


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