Servomechanism design techniques and applications aerospace problems

A cryogenic oxygen flow control servomechanism subsystem is described that is typical for an auxiliary power unit fuel system. Three possible types of feedback for this type of subsystem are: position with velocity feedback accomplished by gear train and synchro-transformer, position with velocity feedback accomplished by adding a rate generator and position feedback with compensating network. Servomechanisms employing any of these three types of subsystems can provide the oxygen flow control desired. The differences in performance relate primarily to steadiness of flow with the companion heat modulation. The damping ratio parameter can be used to achieve a reasonable response time.