Annotation: In the present-day rocket engineering, the liquid rocket engines with pump feed system have gained wide acceptance. As a rule, the pumps used in liquid rocket engines are screw-axifugal. The screw serves to increase pressure upstream of the axifugal wheel, thus ensuring its cavitation-free operation. The screws used in the screw-axifugal pumps of liquid rocket engines may be of two types: with constant and variable step. The screws with constant step are easier to calculate, profile and manufacture as compared to the screws with variable step. As known from the literature, the use of the screw with variable step increases power characteristics of the screw-axifugal pump. The purpose of investigation is comparative analysis of cavitation and power characteristics of the following high-speed low-consumption screw-axifugal pumps of liquid rocket engines with jointed screws, screws of constant and variable step:  RD868 engine oxidizer and fuel pumps;  RD859 engine fuel pumps;  RD861K engine fuel pumps. Besides, the analysis has been made of the impact of design features and geometrical dimensions of the screws with variable and constant step on power characteristics of the screw-axifugal high-speed lowconsumption pumps of liquid rocket engines. Special attention has been given to the analysis of anticavitation properties of the pumps with screws of variable step and pumps with jointed screws. Based on the results of investigation, it has been ascertained that when using the joint screws and screws with variable step instead of the screws with constant step in the high-speed low-consumption screw-axifugal pumps of liquid rocket engines, the pump delivery head increases from 0.65 to 3.83%, the efficiency increases up to 1.7%. The use of jointed screw and screw of variable step as compared with the screw of constant step does not have any impact on cavitation properties of low-consumption crew-axifugal pumps of liquid rocket engines.

Annotation: The Ukrainian companies Yuzhnoye SDO and SE PA YMZ supply VG143 main engine assembly for Vega LV AVUM upper stage, which is a one-chamber LRE of 250 kg thrust with five ignitions in flight. By the present, 11 successful launches of Vega LV have been made. In the process of flight operation, there were no critical comments on engines operation. This LRE has a combination of attractive characteristics, such as high specific pulse, low mass, multiple ignitions in flight, high reliability confirmed by good results of flight test of the prototype engines. The reserve of this engine from the viewpoint of further modernization is far from being exhausted. Enhancing the capabilities of payload injection by launch vehicles into various orbits of artificial Earth satellites is the main task for the developers of ILV as a whole and for the developers of separate assemblies and systems, such as LRE being part of ILV. With consideration for the experience of prototype engines testing, we should note the following ways of main engine assembly modernization: – increasing the specific pulse due to the increase of nozzle expansion ratio; – decreasing the volume of internal manifolds and mass of chamber; – increasing the operation time; – increasing the ignitions number; – increasing the duration of pauses between ignitions and orbital functioning time. Increasing the thrust and specific pulse of Vega LV VG143 main engine assembly and AVUM stage takes place due to the use of pneumopump propellant feeding system instead of standard pressure feeding. Besides, the information is presented on RD859, RD864, RD866 and RD869 prototype engines, the data on their basic characteristics, testing and operation. The below information is of interest to LRE and LV developers.

Annotation: One of the important directions in the development of Yuzhnoye SDO liquid rocket engines is creation of the engines for launch vehicle upper stages, boosters, space tugs and takeoff-and-landing vehicles. The article presents an overview of Yuzhnoye SDO – developed liquid rocket engines, their basic characteristics, distinctive features and the current status of development and operation. The article presents the information on the following engines: RD858 and RD859 operating on storable propellants, for lunar takeoff-and-landing Block E module; RD809M and RD809K operating on liquid oxygen + kerosene created on the basis of RD8 serial control engine of Zenit launch vehicle second stage. In this case, RD809M engine is RD8 version with tight integration and RD809K engine is its one-chamber version; RD805 engine operating on liquid oxygen + kerosene created on the basis of combustion chamber of RD8 serial control engine of Zenit launch vehicle second stage.; RD835 engine operating on liquid oxygen + kerosene created for the second stages of launch vehicles of Mayak type; the engines and propulsion systems operating on storable propellants, such as RD861K (main engine of Cyclone-4 third stage and Cyclone-4M launch vehicle second stage), DU802 (liquid propulsion system of Krechet autonomous space tug of conversion Dnepr launch vehicle), RD840 (apogee liquid rocket engine of liquid propulsion system of geostationary communication satellite bus), VG143 (main engine assembly of the fourth stage of European Vega launch vehicle), RD864 and RD869 (main engines of Dnepr launch vehicle upper stages). The information presented in the article is of interest to liquid rocket engines and launch vehicles developers.

Annotation: Substantiation of the research tools has been performed as a part of methodology development for the air and missile defense system. The problem under consideration is very complex due to the multifactorial nature of the research object, its qualitative variety and manifold structure, incomplete definition of the problem statement. Furthermore, the ability of modern technologies to produce different arms systems, which are capable of carrying out same class tasks, considerably increases the risk of making not the best decisions. Based on this, as well as taking into account the sharp increase in the cost of weaponry, the considered problem is classified as an optimization one that should be solved through the theory of operations research. In this theory, such task is viewed as a mathematical problem, and mathematical simulation is the basic method of research. The main types of mathematical models, their areas of application have been considered as a part of the analysis. The classification of mathematical models has been indicated according to the scale of reproduced operations, purpose, and goal orientation. Quantitative and qualitative correlation of forces has been accepted as the efficiency criterion, which determines a goal orientation of the model. The problems related to this have been shown. In particular, searching for the compromise between simplicity of the mathematical model and its adequacy to the research object is among these problems. Two of the basic approaches to principles of the military operation model construction and its assessment have been considered. The first is implemented through modeling of the combat operations. The second approach is based on the assumption that different armament types can be compared based on their contribution to the outcome of the operation, and on the possibility to assign «a weighting coefficient» named as a combat potential to each of these types. The modern level of problem solving related to this method has been shown. The reasonability of its application in the considered task, including the definition of forces correlation of the opposing parties, has been substantiated. The basic regulations of the construction concept of the required mathematical model and tools for its research have been formulated based on the analysis results: the assigned problem should be solved by analytical methods through the theory of operations research; the analytical model is the most acceptable conception of the analyzed level of the military operation; the synthesis of the model should be based on the idea of a combat potential. At the same time, it should be taken into account that the known approach to the definition of forces correlation, which uses the combat potential method, has a number of essential limitations, including the methodological ones. Therefore, within the bounds of further research, this approach requires the development both in terms of improving the reliability of the single assessment and in terms of giving the system qualities to the synthesized mathematical model.