David A Carpenter

A mass properties measurement system including a test object support table mounted to a bearing means for supporting the table for rotation about an axis of rotation substantially perpendicular to the plane of the support table; means for measuring overturning forces imparted to the measurement table and bearing means by a test object mounted to the support table, wherein the overturning forces tend to rotate the table and bearing means about a pivot axis substantially perpendicular to and intersecting the axis of rotation; induction motor drive means for inducing rotational forces to said support table and bearing means to rotate said support table and bearing means at a predetermined rate of rotation while remaining substantially invisible to said measuring means, the induction motor being mounted to the mass properties measurement system such that substantially all forces imparted to the system by the motor for rotating the table lie in a plane which is substantially perpendicular to said axis of rotation and which contains said pivot axis; and closed loop velocity control means for controllably driving the induction motor to drive the support table up or down to a predetermined rotational speed and to thereafter maintain the table of rotation at said predetermined speed.

Integral torquer for mass measurement system

The mass properties measurement apparatus of this invention includes a pair of opposed bearing assemblies, each comprising a fixed bearing and a movable journal, and a radially rigid connection between the movable journals located on an axis with a single degree of freedom, which is rotation. A test object support table is fixed to one journal for rotational movement therewith, the plane of the surface of the support table being perpendicular to the rotational axis. A torsion wire coincident with the rotational axis is fixed at one end to the one journal for rotation with the support table and is fixed at its other end against rotation with the support table, thereby creating a torsional pendulum which permits oscillatory movement of the support table. Means are provided for measuring successive oscillation periods of the support table for determining the center of gravity and principal axis moments of inertia of a test object on the support table. Finally, a fail-safe caging mechanism is provided. This device engages the shaft under controlled conditions if gas pressure falls below acceptable values thus protecting the bearing surfaces from damage and providing an orderly shutdown.

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Parkton, MD, United States of America

David A Carpenter