Critical Gas Bearing Slew Test Evaluation With a Varmeter

In the Pendulous Integrating Gyro Accelerometer (PIGA) used in inertial guidance systems, the gas bearing wheel is operated in a slewing mode at high slew rates. The high performance criteria of the guidance system require that the gas bearing operate without degradation and without loss of synchronous spin velocity at high slew rates. Size and weight restrictions limit the available support area, requiring that the gas bearing be operated near its maximum capability under high slew rates. An MIT-designed varmeter has been a proven tool to critically evaluate gas bearing performance under high slew rates. The varmeter is sensitive to slightest contact between the rotating member and a stationary member and can detect the slightest loss of synchronous speed.