Automatic Thrust and Mixture Ratio Control of the LE-X

The LE-X is a new cryogenic booster engine with high reliability and low cost, designed for the next-flagship Japanese launch vehicle, called H-X. It will be the first booster engine in the world with an expander cycle. One of the characteristics of the LE-X is automatic control of thrust and mixture ratio (LOX/LH2) using electric actuator valves. The valves will reduce the engine dispersion of thrust and mixture ratio and enable throttling smoothly. The LE-X valve configuration is determined and the control method of the LE-X is verified by the subscale valve test and the transient simulation of the LE-X.