3360. Are You Sure? – Uncertainty in Mass Properties Engineering


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Robert L. Zimmerman, Nakai: 3360. Are You Sure? – Uncertainty in Mass Properties Engineering. 2005, (L. R. ‘Mike’ Hackney Award).



The Mass Property Engineer?s role in the engineering organization is ultimately to report the mass properties of the organization?s vehicle, so that the vehicle?s performance can be characterized. It is insufficient merely to report the mass properties as a discrete entity ? the characterization of performance requires the possible variations of the vehicle?s mass properties also be determined and reported by the Mass Property Engineer to the team. Mass Property Engineers have an expectation, based on precision computerized drafting and manufacturing equipment, electronic mass property tallying, and high accuracy measurement equipment, that the reported mass properties will be very close to the vehicle?s actual mass properties. This paper will unveil the proposition that the carefully determined mass properties reported by the Mass Properties group has far greater dispersions about the reported values than that expectation. The paper is divided into three parts. Part One expands on basic statistical concepts required to determine mass property parameter dispersions. Part Two derives the algorithms necessary to determine overall vehicle mass property uncertainties. Part Three illustrates Parts One and Two using an example, and produces some representative computer code to implement the algorithms.


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