SCIENCE & EDUCATION

pp.179-193

pp. 155-168

pp. 169-176

Application of metal additives to fuels and to pyrotechnic structures (PS) allows us to improve power characteristics both of traditional ramjet (RJ) schemes, and of combined RJ and to realize performance limits for high-metallized PS. It is obvious that advanced designs of RJ using the PS are characterized by a broad range of changing operation conditions such as pressure, ratios of components, structure and quantity of the condensed phase of PS combustion products. Their influence on the main characteristics of the workflow ought to be known to use advantages of the metal-containing combustible as much as possible

The paper emphasizes that owing to micro-arc oxidation coating the performances of spacecraft units from aluminium can be significantly expanded. The properties of micro-arc oxide coatings, which may be achieved by using the cutting-edge covering technologies, are given. The comparative mass reduction as a result of the replacement of greater density metals for the aluminium alloys after the micro-arc oxidation is calculated by example of a typical unit of the spacecraft. The paper offers optimal methods for the micro-arc oxidation of different configurations parts of aluminium alloys.

The article considers process fluids, which are presently applied to aviation hydraulic systems (AHS) in domestic and world practice. Aviation practice uses rather wide list of fluids. Based on the technical specification a designer makes the choice of specific fluid for the specific aircraft. Process fluids have to possess the specified properties presented in the article, namely: lubricating properties; stability of physical and chemical characteristics at operation and storage; low-temperature properties; acceptable congelation temperature; compatibility with materials of units and components of hydraulic systems; heat conductivity; high rigidity; minimum low coefficient of volume expansion; fire-explosion safety; low density. They should also have good dielectric properties, be good to resist to destruction of molecules, have good anticorrosion and anti-erosion properties, as well as not create conditions for emerging electro-kinetic erosion of spool-type and other precision devices, and a number of other properties.

In cutting-edge aerospace technology small gas-generators (SGG) are widely used for creating a high-enthalpy flow with required characteristics. One of perspective unitary fuels for SGG is nitrous oxide (N2O). However, the use of N2O requires solving the problems of initiation and intensification of its decomposition process. The article considers one of the possible solutions to fulfil these tasks by using the resonant gas-dynamic systems (GRS) to initiate a workflow with no electric power. Predesigns and results of tests showed that SGG using the nitrous oxide with GRS has rather long time to reach the nominal operation conditions and rather low extent of decomposition of N2O. The paper offers to determine experimentally the efficiency of the catalytic blocks used in SGG with GRS-based devices to initiate the workflow. It presents the following: an installation diagram, a technique to conduct experiments and their results, as well as a complex analysis of data and a comparison with calculations. The obtained data allow us to draw a conclusion that with using the catalytic blocks, there is a possibility to accelerate bootstrap operation of SGG and  increase the efficiency of decomposition of N2O.

Analytical approach to a problem of the multicriteria optimization, being alternative to expensive cost calculation numerical methods of sounding of space of parameters is considered. The statements allowing on characteristics of a comonotonicity and contramonotonicity are formulated and to the angular characteristic of anti-gradients to define парето - optimum decisions. The received results are applied to a problem of parametrical synthesis of double-circuit control systems by movement of missilies. The possible directions of improvement of inconsistent criteria of time of increase and reregulation are shown and limits of parametrical correction are noted

The paper describes a mathematical model for simulating a flexible thread unrolling from a bobbin. The real kinematics of unrolling is considered, but the problem of contact between the thread and bobbin is avoided. This results in great reduction of model «stiffness». The model has a constant dimension thereby simplifying the algorithm. The feature of this model is that there is no need to have many nodes on one thread turn to ensure stability and convergence. This model is tested by the simplified problem of Heliogyro solar sail deploying. From simulation results it is clear that a transversal motion of solar sail is almost independent on simulation model parameters, i.e. the model convergence.

Equipment operation safety and ecology of the ground complexes is one of the defining factors to choose a component of the rocket fuel. The Liquefied Natural Gas (LNG) having a number of advantages over the rocket kerosene has a specific storage feature that is a possibility of the rollover phenomenon to be arisen. Now the Russian Federation has no sufficient experimental LNG base to simulate different processes, including a rollover. Basic data for modeling are taken from various sources to reveal a doubtful reliability. To confirm data compliance, modeling results have been compared to the experimental data.

Refrigerating of high-boiling rocket fuel is needed to reduce its density and to create cold reserve for equalization of fuel heating during preparing and launching operations. Liquid nitrogen is cheap and ecologically clean product, which can be easily used as a source of cold in rocket fuel preparing systems. Refrigerating systems with liquid nitrogen injection, intermediate heat carrier and heat exchanger are used in temperature preparing of high-boiling rocket fuel components with relatively high freezing point. The operation principle of such system is based on liquid nitrogen injection into heat carrier and refrigerating a rocket fuel component with recuperative heat exchanger. The paper considers simulation techniques and results of such a system performance.

The paper concerns one of new ways to improve the interface of a modern aircraft cockpit, namely a 3D-audio technology application. The 3D-audio is a technology that reproduces the spatially directed sound via earphones or loudspeakers. Spatial audio-cues together with information about a danger, which also point out the direction it emerges from, can reduce the time of response to the event, thereby increasing the situation safety of flight.The offered paper describes the approved methods to implement the 3D-audio technology. It also presents results of experiments on evaluating the accuracy characteristics of localized directions towards the sound source for some types of audio signals.A scientific novelty is to achieve the true-to-life quantitative characteristics of 3D-audio technology to be appropriate for the modern aircraft cockpit interface design.

The paper presents calculations to determine a penetration depth into low-strength soil targets provided by penetrators equipped with the pulse jet engine when studying a structure of space object blanket. In movement the penetrator is considered as a rigid body of variable mass, which is subjected to the drag force and the reactive one applied at the moment the jet engine fires. Dynamics of moving penetrator with its conic nose part is described with binomial empirical law of target drag force and with assumption that the jet thrust force is constant during its application time. It is established that penetration depth into low-strength soil target can be several times increased owing to use of the jet engine. A rational time for the jet engine firing and operation is defined.

The article presents a description of operation of an electrical nonlinear circuit model including a source (thermo-emission reactor), a plasma current converter (thermo-emission diode) and a resistive load. Amplitude-frequency responses (AFR), phase-frequency characteristics (PFC), phase curves and load current waveforms against the parameters of the thermo-emission diode were studied along with operation stability of the following circuit: thermo-emission reactor – thermo-emission diode - resistive load. The operation of this electrical nonlinear circuit was simulated by using MATLAB - SIMULINK software package; this allowed to obtain accurate solutions for AFR and PFC. Results of circuit operation dynamics were obtained for different current waveforms (sine-wave and meander-wave). Areas of possible unstable operation of the spacecraft propulsion system which depends on reactive resistances of the thermo emission reactor and the plasma current converter were presented.

The authors consider a possibility of using a Hall Effect thruster working with an ambient atmospheric gas for orbital station-keeping. Relation between thrust and atmospheric drag force was obtained. It was shown that there is a critical value of accelerating voltage which provides equality of thrust and air drag force. Relation between this critical accelerating voltage and spacecraft velocity, as well as relation between thrust efficiency and the ratio of air intake area to the spacecraft's area, were obtained. Basic ways of improving efficiency of the air breathing Hall Effect thruster were proposed.

Effect of the torque in the thruster with anode layer was considered. It was shown that the mechanism of appearance of such torque is associated with the azimuthal deflection of ions in the accelerating channel of an engine as it moves in the radial magnetic field. Dependences between the angular acceleration of a device and the strength of magnetic field for different thruster’s operating modes, different working substances and mass-dimensional characteristics of the spacecraft were obtained. It was also demonstrated that this torque could have a significant impact on the stabilizing system in cases of long-time operation. The remedy for harmful influence of the azimuthal deflection of ions on the spacecraft’s rotation was proposed.

The frontier of linear spatial filtration during interference elimination of a spatially-heterogeneous background was considered in this article. It is supposed that the effect of linear filtration depends on parameters of the correlation function of the background and characteristics of an optic-mechanical block. The achievable degree of interference elimination, obtained as a result of analytical statistical estimation, was compared with the values required for a difficult background. The authors estimated the degree of signal suppression from the edges of interfering formations on a “step” model and on a video frame with a real difficult background. The obtained results demonstrated that the class of linear filters does not provide comprehensible indicators of interference elimination during observation of targets on difficult background ensembles.

In this paper results of experimental studies of integrated characteristics of a laboratory model of a stationary plasma thruster of new generation, which is α-40, calculated at the rate of total power consumption equaling 150 W were presented. Integrated parameters of this model, such as thrust, discharge current, specific impulse and efficiency obtained at test-benches of MSTU MIREA and OKB "Fakel" were almost identical. Thus, at the input power of ~150 W, voltage of 210 V, consumption of xenon of 0,7 mg/s, thrust appeared to be 9.4 мN, the anode specific impulse of thrust was equal to ~1370 s, and the anode efficiency, taking into account the power consumed by magnetic coils, equaled to 41%. Another mode with a bigger thrust (9.7 мN) but with a smaller specific impulse (1240 s) at the same input power was received at the consumption of xenon of 0.8 mg/s and voltage of 190 V. Efficiency was about 40%. The semi-angle of divergence of a plasma beam was equal to ±25 °. Predicted life expectancy was approximately 2500 hours. The data provided in the paper showed that α-40 is more efficient than any known analogues.

Different variants of worst-case situations involving space cable systems of small length during uncontrolled deployment were considered in this paper. As a rule, these situations are caused by an abrupt change in the tensile force of the cable. This leads, depending on the flick, to a springing of the end-bodies and their return motion with the risk of collision, or to a break of the cable system, followed by independent movement of the end-bodies. In addition, worst-case situations may be caused by collisions of the cable with micrometeorites or debris objects that are likely to lead to a sudden breakage. In examples, development of the discussed situations was analyzed; absence of collisions in cases of dangerous approaching of end-bodies was demonstrated. It was proposed to introduce design features for increasing safety of uncontrolled deployment in potentially dangerous situations. Analytical and numerical methods were used for solving the motion problem after separation. Analytical solution of simultaneous motion of two bodies in orbit was used for extracting information about the distance between bodies during their motion. Numerical solution uses a model of the cable system in the form of a chain of weighty material points connected by viscoelastic links. In this model there are solid end-bodies; presence of end friction dampers is also simulated; influence of the Earth non-sphericity and atmospheric drag was taken into account. With the use of numerical solutions a set of trajectories was obtained; cases of dangerous approaching of end-bodies were demonstrated. For such situations it was suggested that cable sections with regulated break force should be used. Forms and motion trajectories of developed cable systems were presented. Methods used in this paper can be applied to planning and justifying safety of spacecraft flights with uncontrolled deployment of the space cable system.

Relevance of this work is associated with the problem caused by ever-increasing usage of cryogenic fluids in the space rocket technology. Further exploration of space is impossible without creation of orbital cryogenic gas stations. A distinctive feature of all cryogenic liquids is a non-uniform distribution of density and temperature observed during all modes of operation and storage. A suitable model for studying motion of a mechanical system is a heterogeneous incompressible fluid. In this work interaction between a heterogeneous incompressible fluid and a movable rigid body’s cavity was discussed. Cases in which motion of a rigid body is caused by the action of momentary forces or cases of abrupt movement were considered. The authors proposed a concept of quasi-potential of fluid velocities was introduced; solution to the problem of motion of a rigid body with a cylindrical cavity partially or completely filled with a cryogenic liquid.