Annotation: The article dwells on the problem of enhancement of durability for the mechanical rubber articles, which is directly related to the enhance of rubber resistance to various types of heat aging. Heat resistance during compression is most important for rubbers used for seals of various types: rings, collars, armored collars, gaskets for aviation and rocket technology hardware. Stress relaxation and the accumulation of relative residual deformation of rubbers, caused by the kinetic rearrangement of chemical bonds, are extremely sensitive to the influence of high temperatures. The main cause of the defects is the loss of elastic properties of the seals because of the accelerated heat aging of the nitrile group under conditions of long-term exposure to elevated temperatures in conditions of hot climate. The results of accelerated climatic testing of specimens of mechanical rubber articles, as well as the results of climatic endurance testing of the units for the period simulating 20-year service life are specified, and the main types of defects which result in the loss of performance properties of the mechanical rubber articles are as follows: great (up to 100%) residual deformation of intersections, cracking, loss of elasticity. The warranty life of fuel system units, made of ИРП-1078 nitrile rubber, does not exceed 12 years. Replacing the existing rubbers with rubbers created on the basis of more heat-bearing rubbers is the most promising way to improve the performance properties of the mechanical rubber articles under the high temperatures. The new D2301 rubber is based on fluorosiloxane rubber. It provides high thermal stability and, especially, the ability to maintain high performance properties for a long time under the simultaneous impact of hostile environment and high temperatures. The results of climatic endurance testing of fuel system units, equipped with rubber articles made of D2301 rubber, fully justify the increase of the specified service life of the specified units from 12 to 16 years. It is recommended to introduce D2301 rubber into the effective normative documentation and continue studies in order to extend the nomenclature of mechanical rubber articles made of D2301 rubber to provide the reliable sealing of units during the service life of 16 years or longer.

Annotation: Despite stringent environmental requirements, modern launch vehicles/integrated launch vehicles (LV/ILV) burn toxic propellants such as NTO and UDMH. Typically, such propellants are used in the LV/ILV upper stages, where a small amount of propellant is contained; however, some LV/ILV still use such fuel in all sustainer propulsion stages. For launch vehicles containing toxic rocket propellants, flight accidents may result in the failed launch vehicle falling to the Earth’s surface, forming large zones of chemical damage to people (the zones may exceed blast and fire zones). This is typical for accidents occurring in the first stage flight segment, when an intact launch vehicle or its components (usually individual stages) with rocket propellants will reach the Earth’s surface. An explosion and fire following such an impact will most likely lead to a massive release of toxicant and contamination of the surface air. An accident during the flight segment of the LV/ILV first stage with toxic rocket propellants, equipped with a flight termination system that implements emergency engine shutdown in case of detection of an emergency situation, has been considered. To assess the risk of toxic damage to a person located at a certain point, it is necessary to mathematically describe the zone within which a potential impact of the failed LV/ILV will entail toxic damage to the person (the so-called zone of dangerous impact of the failed LV/ILV). The complexity of this lies in the need to take into account the characteristics of the atmosphere, primarily the wind. Using the zone of toxic damage to people during the fall of the failed launch vehicle, which is proposed to be represented by a combination of two figures: a semicircle and a half-ellipse, the corresponding zone of dangerous impact of the failed LV/ILV is constructed. Taking into account the difficulties of writing the analytical expressions for these figures during the transition to the launch coordinate system and further integration when identifying the risk, in practical calculations we propose to approximate the zone of dangerous impact of the failed LV/ILV using a polygon. This allows using a known procedure to identify risks. A generalization of the developed model for identifying the risk of toxic damage to people involves taking into account various types of critical failures that can lead to the fall of the failed LV/ILV, and blocking emergency engine shutdown during the initial flight phase. A zone dangerous for people was constructed using the proposed model for the case of the failure of the Dnepr launch vehicle, where the risks of toxic damage exceed the permissible level (10–6). The resulting danger zone significantly exceeds the danger zone caused by the damaging effect of the blast wave. Directions for further improvement of the model are shown, related to taking into account the real distribution of the toxicant in the atmosphere and a person’s exposure to a certain toxic dose.

Annotation: The possibility is considered of using rocket propellant thermal neutralization units for decontamination of dangerous industrial wastes. The advantages of thermal neutralization units are considered, their operating principle is described, by the example of high-temperature toxic rocket propellants, the chemical reactions that take place in combustion chamber are formulated. The combustion chamber is a component of the neu tralization unit, it is in the combustion chamber, in the environment of created high temperatures, that the process of elimination of dangerous substances takes place. Taking into consideration the high cost of neutralization units, which will be a factor hindering the wide-scale introduction of neutralization units to decrease technogenic load on environment of Ukraine, the option is proposed of reducing the costs during the use of thermal neutralization units by way of combining the function of oxidizer neutralization unit and fuel neutralization unit in a single universal neutralization unit. The article substantiates the topicality and necessity of works to create the universal thermal neutralization unit from the viewpoint of economic and ecological aspects. The article presents a generalized description of technology and methodology of research tests of pilot samples of assemblies for high-temperature rocket propellants vapor and industrial wastewater supply into the neutralization unit. The assemblies for high-temperature rocket propellants vapor and industrial wastewater supply are considered as most critical components of the universal neutralization unit from the viewpoint of neutralized substance changing. The experiments were conducted on water solutions of rocket propellants that in this case simulated the contact of internal cavities of supply assemblies with aggressive toxic media. The conditions were created at which the probability existed of interaction of rocket propellants residues in stagnation zones at the moment of changing the supplied propellant component. In the frameworks of research tests of pilot samples, the obtained results were considered and analyzed. The findings are presented that confirm practical feasibility of using integrated supply assemblies.

Annotation: The article analyzes the energy potential of alternative sources of Ukraine. The projects using hydrogen technologies aimed at attracting solar energy to the infrastructure of energy technological complexes, in particular water desalination systems and for refueling automobile vehicles located in areas with high solar radiation potential, are considered. During the operation of water desalination plants using a solar power station as an energy source, contingencies are very likely to arise due to either a power outage (due to cloudy weather) or an emergency failure of individual elements of the system. In this case, it is required to ensure its removal from service without loss of technological capabilities (operability). For this purpose, it is necessary to provide for the inclusion in the technological scheme of the energy technological complex of an additional element that ensures operation of the unit for a given time, determined by the regulations for its operation. As such an element, a buffer system based on a hydrogen energy storage device is proposed. The current level of hydrogen technologies that are implemented in electrochemical plants developed at the Institute of Mechanical Engineering named after A. N. Podgorny of the National Academy of Sciences of Ukraine allows producing and accumulating the hydrogen under high pressure, which eliminates the use of compressor technology.

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: The exploratory and experimental investigations were conducted into design of propellant tank made of composite polymer materials for work in cryogenic environment at operating pressure of 7.5 kgf/cm2 . When determining the configuration of a liner-free composite propellant tank, the main requirement was ensuring its leak-tightness at internal excess pressure and cryogenic temperature effect. The world experience of creating similar designs was analyzed and the requirements were defined imposed on configuration of propellant tank load-bearing shells. Before defining the final configuration, the types of materials, reinforcing patterns, and possible ways to ensure leak-tightness were analyzed, and preliminary tests were conducted of physical and mechanical characteristics of thin-wall samples of composite materials and tubular structures with different reinforcing patterns. The tests of carbon plastic samples were conducted at different curing modes to determine the most effective one from the viewpoint of strength characteristics and the tests for permeability by method of mouthpiece were conducted. The tests of pilot propellant tank showed that the calculated values of deformations and displacements differ from the experimental values by no more than 10 %. Using the parameters measurement results from the tests on liquid nitrogen, the empirical formulas were obtained to calculate linear thermal expansion coefficient of the package of materials of load -bearing shell. The empirical dependences were constructed of relative ring deformations at load-bearing shell middle section on pressure and temperature. The tests confirmed correctness of adopted solutions to ensure strength and leak-tightness of propellant tank load-bearing shell at combined effect on internal excess pressure and cryogenic temperature, particularly at cyclic loading. The materials used and propellant tank manufacturing technologies ensure leak-tightness of load-bearing shell at liquid nitrogen operating pressure of 7.5 kgf/cm2 and strength at excess pressure of 15 kgf/cm2 and allow conducting approbation of prospective stage of the integrated launch vehicle.

Annotation: The main parameters are understood as: carrying capacity mг, range L and fuel efficiency qт, which largely determine the competitiveness of aircraft of this type, including military transport aircraft. The reason for the creation of modifications of transport category aircraft is the requirement for a constant increase in their flight performance by increasing the carrying capacity and range. Among the main goals of implementing such decisions there is an indispensable increase in the fuel efficiency of modifications, since the cost of fuel reaches 80 % of the cost of an airplane hour during operation. There are a number of models that make it possible to assess the influence of the weight and aerodynamic parameters of the airframe of the aircraft and the fuel performance of the power plant (specific engine consumption) on the integral indicator of the fuel efficiency of the modification at cruising mode and the average hourly fuel consumption at the certification stage, when all parameters of the airframe and engine are fixed and consideration of options is not possible. A new model is proposed for the stage of designing modifications, in which deep modification changes are made in the geometry of wing and in the power plant with various variants of their correlation and coordination. The parameters of new model: specific fuel efficiency – specific route productivity, in order to form the relative carrying capacity and relative range of action for the required specific fuel efficiency. An analysis of such dependencies showed: – with an increase in relative range L , fuel costs per flight also increase; – the adequacy of changes in route performance is observed only at L < 0.5. At L > 0.5 productivity is constantly decreasing, while the specific indicator of fuel consumption per unit of work increases exponentially; – if in the analysis we take into account the specific value of transport efficiency, that is, the characteristic “load – range” ( mп.н  f L ), it becomes obvious that the most favorable (from the point of view of fuel efficiency) are relative ranges of 0,3 < L < 0,5. In this range L , not only acceptable fuel efficiency values are realized, but also the maximum value of the route performance, that is the main parameters for which modifications are developed.

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 structure examined herein aims to keep fuel from entering the space behind the cuff, evacuate the space behind the cuff, reliably fasten the cuff to the thermal protective coating of the bottom in the process of charge forming, easily release the cuff after charge forming, and remove the support structure elements from the casing after charge polymerization when equipping. The structure was tested in the process of fueling the solid rocket motor casing and during charge polymerization. In order to comply with the specified requirements the cuff functions were identified, the structures previously developed were analyzed, and a new structure was designed and improved after testing. The improved structure ensured that fuel did not enter the space behind the cuff; it was removed easily after charge forming. Conclusions proved the suitability of this stricture.

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.