Annotation: The study of thermal strength of the hold-down bay is considered. The hold-down bay is a cylindrical shell with the load-bearing elements as the standing supports. The case of the hold-down bay consists of the following structural elements: four standing supports and the compound cylindrical shell with two frames along the top and bottom joints. The purpose of this study was the development of a general approach for the thermal strength calculation of the hold-down bay. This approach includes two parts. Firstly, the unsteady heat fields on the hold-down bay surface are calculated by means of the semi-empirical method, which is based on the simulated results of the combustion product flow of the main propulsion system. The calculation is provided by using Solid Works software. Then the unsteady stress-strain behavior of the hold-down bay is calculated, taking into consideration the plastoelastic deformations. The material strain bilinear diagram is used. The finiteelement method is applied to the stress-strain behavior calculation by using NASTRAN software. The thermal field is assumed to be constant throughout the shell thickness. As a result of the numerical simulation the following conclusions are made. The entire part of the hold-down bay, which is blown by rocket exhaust jet, is under stress-strain behavior. The stresses of the top frame and the shell are overridden the breaking strength that caused structural failure. The structure of the hold-down bay, which is considered in the paper, is unappropriated to be reusable. The hold-down bay should be reconstructed by reinforcement in order to provide its reusability.

Annotation: Due to an increase of power of rocket engines, the high intensity sound field generated by the exhaust jets have become an important factor, which determines the success rate of a rocket launch. Ensuring a successful launch of a rocket system became harder due to new engineering problems. Identification and definition of acoustic sources structure within a complex supersonic jet, being a one of the most important scientific problems, which have to be solved to find the ways to control accoustic radiation. A three components of acoustic sources can be defined here – broadband signals from large and small components of of turbulent jet and tonal signals which usually being overlooked during the estimation of overall sound pressure level. The paper considers various aspects of acoustics of the launch of rocket systems, which includes characteristics of acoustic sources in supersonic jets, possibilities and physical limitation factors, under which it is possible to control the sound radiation. Among the possible ways to control the process of sound generation by a jet, a method of water injection in a jet is being studied. While saving the general thrust of the engine this method can not greatly reduce the sound radiation by a jet. It is recommended to use big amounts of water-air mix to protect the launch pad from damage. Significant progress on the topic of understanding the process of sound generation by supersonic jets can be achieved via mathematical modeling of sound radiation. The latest achievements of mathematical modeling of sound generation by supersonic jets being presented.

Annotation: Launch vehicle lift-off is one of the most critical phases of the whole mission requiring special technical solutions to ensure trouble-free and reliable launch. A source of increased risk is the intense thermal and pressure impact of rocket propulsion jet on launch complex elements and on rocket itself. The most accurate parameters of this impact can be obtained during bench tests, which are necessary to confirm the operability of the structure, as well as to clarify the parameters and configuration of the equipment and systems of complex. However, full-scale testing is expensive and significantly increases the development time of the complex. Therefore, a numerical simulation of processes is quite helpful in the design of launch complexes. The presented work contains simulation of liquid rocket engine combustion products jet flowing into the gas duct at the rocket lift-off, taking into account the following input data: the parameters of propulsion system, geometric parameters of launch complex elements, propulsion systems nozzles and gas duct. A three-dimensional geometric model of the launch complex, including rocket and gasduct, was constructed. The thermodynamic parameters of gas in the engine nozzle were verified using NASA CEA code and ANSYS Fluent. When simulating a multicomponent jet, the equations of conservation of mass, energy, and motion were solved taking into account chemical kinetics. The three-dimensional problem was solved in ANSYS Fluent in steady-state approach, using Pressure-based solver and RANS k-omega SST turbulence model. The calculation results are the gas-dynamic and thermodynamic parameters of jets, as well as distribution of gas-dynamic parameters at nozzle exit, in flow and in boundary layer at gas duct surface. The methodology applied in this work makes it possible to qualitatively evaluate the gas-dynamic effect of combustion products jets on gas duct for subsequent optimization of its design.

Annotation: The process of creating modifications of aircraft in the transport category is a very relevant and widespread phenomenon in modern aircraft construction. A separate group of military transport aircraft has been distinguished in connection with the specific character of their mission: – the need to formulate the characteristics “cargo – range” for light, medium, operational tactical and strategic military transport aircraft, since it is precisely according to this characteristic that they are positioned by their purpose; –specific requirements are imposed on military transport aircraft cargo compartment not only with respect to its geometrical dimensions and usable volume, but also with respect to the possibility of simultaneous accommodation of military equipment and people, as well as the placement of a stretcher with t he wounded during their evacuation from the war zone; – the possibility of airborne landing of military equipment and paratroopers, which requires specific hatches and means of maintaining weight balance in flight; – the possibility of basing on poorly prepared sites with a runway length of less than 800 m in the short take-off and landing (STL) mode, especially for operational tactical military-technical vehicles, which significantly expands their use in combat zones; – the possibility of conversion into a civilian aircraft: for the delivery of goods to areas of the far north, when fighting fires, when evacuating victims from disaster zones, etc. The article shows that creation of modifications of expensive military transport aircraft is the main direction of their development. All leading aircraft manufacturing companies in the world use modification procedures as the way to most quickly meet constantly changing requirements for military transport aircraft. Along with the traditional methods of designing the modifications, the domestic school proposed a new methodology for determining the necessary parameters for “deep” modifications in wing geometry and propulsion system. The methodology is based on the use of three principles: – ensuring growth of carrying capacity and the required range of modifications of military transport aircraft of various purposes; – geometric re-arrangement of wing and system of carrying surfaces “wing + tail units” according to the criterion of minimum inductive resistance when lifting forces are equal to basic version; – coordination of modifications in wing with the required parameters of propulsion system as a condition for ensuring the required fuel efficiency.

Annotation: Contemporary trends in developing space-rocket hardware indicate the increased demand for light and ultra-light rockets. The first trend in developing the up-to-date light and ultra-light rocket hardware includes improving accuracy of cargo delivery to the specified area; the second trend covers the enhancement of energetic properties and the reduction of production and operational costs. Spinning about the longitudinal axis of symmetry may be one of the ways to improve the light and ultra-light rocket hardware in these trends. Spinning significantly increases stability of a moving object and partially evens out the negative impact of external and internal disturbing factors (skewness and eccentricities of propulsion system and control elements, wind). Refusal to use systems that provide stabilization about the longitudinal axis of symmetry leads to reduction in mass of the control system equipment, thus increasing energetic perfection of the rocket hardware. Hence, rotation of the rocket about the longitudinal axis may be caused by the spinning elements on purpose as well as by disturbing impacts in case of control failure in the roll channel. This article considers suggestions on algorithmic realization of light rocket control methods under conditions of rapid rotation about the longitudinal axis for each of the options mentioned above. This article offers control methods for the rocket, rotating about the longitudinal axis, that provide angular stabilization, improve the transient quality, and determine the angle of roll after program stop of rotation about the longitudinal axis.

Annotation: Basic dynamic properties of the reentry part of the aircraft-type first stage were examined when turbojet engine is used in the recovery phase. Such configuration can be of interest because turbojets have considerably smaller rate of flow in comparison to rocket engines. Moreover, they are launched in the lower stratosphere or in the troposphere so that there is no need to place oxidizer supply on board. This recovery plan differs from an alternative rocket recovery system and, from our point of view, provides more efficient usage of the fuel stores because it doesn’t require the main propulsion to be started in the recovery phase. Besides the analysis of qualitative characteristics of the descend phase for this stage, the efficiency of a wing with moderate values of maximum aerodynamic characteristics and a turbojet was studied. In this case three ways for stage recovery were investigated. The first one implied unguided descend with zero angle of attack assuming that the stage is statically stable. This descend trajectory was considered as standard and was used to evaluate the efficiency of the wing and turbojet with relatively small propulsion. The second and the third design cases offered the gliding guided descend with turbojet being started only in the lower stratosphere. The last two cases used the same program for the angle of attack. The possibility to ensure permissible overload values at the critical points of the descend trajectory and acceptable values of kinematic characteristics at the earth surface tangency point are also of great interest. Thereby the program for the angle of attack was developed in a way that allowed kinematic characteristics on touchdown be as close as possible to the corresponding values, shown by civil and/or military-transport heavy aircraft. Simulation was conducted on Microsoft Visual Studio 2010.

Annotation: The main scientific and methodological propositions for designing single-stage guided missiles with main solid rocket motors that are intended for delivering payload to the given spatial point with required and specified kinematic motion parameters are defined. The aim of the article is to develop methodology for the early design phase to improve the basic characteristics of guided missiles, including formalization of complex problem to optimize design parameters, trajectory parameters and motion control programs for guided missiles capable of flying along the ballistic, aeroballistic or combined trajectories. The task is defined as a problem of the optimal control theory with limitations in form of equality, inequality and differential constraints. An approach to program forming is proposed for motion control in the form of polynomial that brings the problem of the optimal control theory to a simpler problem of nonlinear mathematical programming. When trajectory parameters were calculated the missile was regarded as material point of variable mass and the combined equations for center-of-mass motion of the guided missile with projections on axes of the terrestrial reference system were used. The structure of the mathematical model was given along with the calculation sequence of criterion functional that was used for optimization of design parameters, control programs and basic characteristics of the guided missile. The mathematical model of the guided missile provides adequate accuracy for design study to determine: overall dimensions and mass characteristics of the guided missile in general and its structural components and subsystems; power, thrust and consumption characteristics of the main engine; aerodynamic and ballistic characteristics of the guided missile. The developed methodology was tested by solving design problems. Applications of the developed program were studied to present the research results in a user-friendly form.

Annotation: In the pneumohydraulic systems of liquid rocket engines and propulsion systems, electromagnetic valves that allow making the pneumohydraulic systems more simple and ensuring multiple ignition of liquid rocket engines have found wide application. The Yuzhnoye-developed electromagnetic valves are designed according to two schemes – of direct and indirect action. In the direct-action electromagnetic valves, the shutting-off device opens (closes) the throat with the force developed by electric magnet. They have gained acceptance in the pneumohydraulic systems with the working medium pressure of ~8.5 MPa, they are of simple design and have high operating speed (0.001…0.05 s). In the electromagnetic valves with amplification, the electromagnet armature is connected with control valve and the main shutting-off device moves due to the force from working medium pressure drop on it. They are used in the operating pressure range of 0.5…56 MPa, at that, the action time is 0.025…0.15 s. For the European Vega launch vehicle fourth stage main engine assembly that has pressure propellant feeding system, the electrohydraulic valve with amplification and drainage was developed. The dependence of this electrohydraulic valve high speed from the line’s output length is decreased to the maximum due to the installation of Venturi nozzle at the output connecting branch. This electrohydraulic valve is operable at the pressure below 8 MPa, the action time is 0.08…0.12 s. The present-day spacecraft gas-jet orientation and stabilization systems use as propulsion devices the electromagnetic valves with nozzles whose thrust is, as a rule, not more than 30 N and the working medium pressure is up to 24 MPa. Yuzhnoye State Design Office developed for 15B36 gas-jet system the electropneumatic valve with amplification and nozzle, which is operable at the pressure below 45 MPa, ensures the action frequency of up to 10 Hz and is capable of creating the thrust of 100 N on gaseous argon. To solve the task of decreasing the dependence of operability and high speed of electromagnetic valves with drainage and amplification on geometry of lines in which a valve is installed, the electropneumatic valve was developed that has spool elements ensuring reliable and quick action with long input lines of 0.004 m diameter. Its mass is 2…2.5 times lower than the mass of analogs. Recently, Yuzhnoye State Design Office develops the apogee RD840 LRE with 400 N thrust, for the conditions of which the direct-action electrohydraulic valve was developed and tested with the following characteristics: pressure – up to 2.15 MPa, consumed power in operation mode – less than 7.1 W, action time – not more than 0.02 s, mass – 0.19 kg. The presented electromagnetic valves by their technical and operational characteristics meet the highest world requirements and have found wide utility in liquid rocket engines and propulsion systems.

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.