Gyrostats and Cardanic Suspended Gyros

Abstract

Following Lord Kelvin, the term gyrostat is used to describe a rigid body that contains in its interior a symmetrical rotor. This latter can rotate about an axis that is fixed with respect to the body and it therefore has one degree of freedom vis-à-vis the enveloping body. In this case it is assumed that the rotation of the rotor relative to the body takes place about the axis of symmetry of the body itself and that, consequently, the mass distribution of the overall system, i.e. of the gyrostat as a whole, is not in any way changed as a result of the rotations of the rotor. It is therefore possible to dèfine constant moments of inertia for the gyrostat system consisting of two bodies and then to calculate the motions of the gyrostat, the procedure being rather similar to that used in the case of a single rigid body.