Abstract: Disclosed is a roll rate sensor which may form part of a roll position sensor (an "up-sensor") and which comprises a vibratory element rotated by a motor within a projectile body so its rotation speed about the projectile axis is the sum of the motor speed and the projectile roll rate. The resultant centrifugal force acts on the element so as to vary its effective stiffness and hence its vibration frequency. A transducer is arranged to provide a signal corresponding to the vibration and hence to the centrifugal force and the roll rate. The vibratory element may comprise a metallic or silicon beam element.

Abstract: A hydrodynamic gas journal bearing system using rotating bushes which are able to radially move relative to a shaft, the movement being controlled by a spring support system, and in which a degree of dynaMic imbalance of the rotating system is incorporated, these features and the design of the system being together such as to suppress the onset of self-excited instability (half-speed whirl) of the rotating system.

Abstract: Stirling cycle apparatus including a compressor or expander for cyclically compressing or expanding a working gas, a displacer for cyclically displacing the working gas, a rotatable shaft, and a drive mechanism for coupling the compressor or expander and the displacer to the shaft, the drive mechanism being such that the relative timing of their operating cycles can be altered. Additionally a low vibration compressor or expander is provided.