System for controlling the nozzle throat area of a rocket motor

In a missile having a motor with an exhaust nozzle the throat area of which is controllably variable to correspondingly vary the thrust developed by said motor, the combination of:

• means for sensing sequential changes in pressure within said motor and developing an electrical output signal representative of such pressure changes;
• a source of an input command signal representative of desired pressure changes within said motor over a given period of time;
• means for comparing the input command signal from said source with the signal output of said sensing means to develop an error signal;
• control means, including a movable pintle and an electrically-controlled hydraulically-pressurized servo valve connected thereto, for varying the throat area of said nozzle;
• means for moving said pintle as a function of changes in the amplitude of said error signal to thereby regulate the operation of said control means;
• said error signal being applied to said servo valve to regulate the amount of hydraulic pressure applied to said pintle and hence the instantaneous position of the latter;
• means for sensing the instantaneous position of said pintle and for developing an electrical variation representative thereof, and means for applying the electrical variation representative of the instantaneous position of said pintle to said control means to decelerate movement of the pintle during a period of rapid changes in pressure within said motor.