2353. Calculating Ellipse of Inertia With Non-Orthogonal Moi Measurements

Paper

Abstract

When you have to perform a mass property measurement, you can either use your own facility (if you have) or rent one; in the latter case you rent the facility together with its fixtures that may not be fully adequate to your purpose. This study rises from practical difficulties faced when planning to perform the measurement of inertia ellipse points of a big satellite (ARTEMIS) in its launch configuration. The aim of the measurement is to calculate the inertia ellipse on a typical plane of the satellite. Envelope problems have led to the impossibility of investigating all the angles in the plane, being the satellite not allowed to rotate 360deg about its longitudinal axis, using the available L-shaped fixture on a SCHENK machine. Therefore the MOI measurements have been performed about three axes having with a reference satellite axes angles of 0deg, +28deg and -28deg (max allowed rotation). In this paper the problem has been generalized and it is mathematically shown how to calculate the inertia ellipse equation parameters having three MOI values about three different axes at any angular position in the plane of the ellipse. The test results showing the goodness of the method are also presented.