This article carries out studies on the stability characteristics of liquid fuel rocket engines within a relatively large range of variations. The research work was carried out centering around the speed and efficiency characteristics of combustion chambers. This article sets out the results of relevant experiments and theoretical calculations. From the angle of the combustion processes within combustion chambers, there were clear indications of the status of the effects of various processes (for example, evaporation or vaporization, mixing, chemical reactions, etc.) following along with changes in the operational status of variable thrust engine combustion efficiency. ANNOTATION: Reprint: Studies on the Combustion Efficiency of Liquid Fuel Rockets with Variable Thrust--Translation.