An Electrically Operated Hydraulic 

 Control Valve 



By J. W. SCHAEFER 



(Manuscript received August 3, 1956) 



The electrohijdraulic transducer used in the servos that drive the control 

 surfaces of the NIKE missile is described and its operating characteristics 

 are discussed. Special attention is directed to the secondary dynamic forces 

 that exist in a high-gain device of this type and to the resulting tendency to 

 oscillate. The application of the valve to a servo system is discussed briefly. 



IXTRODUCTIOX 



Early in the study of the NIKE guided missile project, it became 

 apparent that the requirements for the fin actuators could not be ful- 

 filled by the servo-mechanisms available at that time (1945). All exist- 

 ing types failed to meet the combined rec^uirements of small size, light 

 weight, high torque, and rapid response. Further investigation showed 

 that the development of a hydraulic servo employing an electrohy- 

 draulic transducer appeared to provide a promising solution. A control 

 system of this type, therefore, has been developed for the NIKE missile. 



The design of the transducer, or control valve, was one of the principal 

 problems in the development of the missile control systems and is the 

 subject of this article. The specific design of the valve that will be dis- 

 cussed here is knoAvn as "Model J-7", and represents the state of the 

 development in 1950. Valves of this type, with varying degrees of modifi- 

 cation, are used in missiles of several other projects. 



APPLICATION 



Fig. 1 is a simplified schematic of the roll positioning system in the 

 NIKE missile. It is the simplest of the three applications of the valve in 

 the missile, but will serve to illustrate the situation in which the valve 

 operates. The purpose of the roll servo is to keep the missile in a predict- 

 able roll orientation. 



711 



