2015. № 80

The research subject matter is the mathematical model of maneuvering aircraft altitude and speed sensor.

The aim is to increase the altitude and speed measuring accuracy during the maneuverable aircraft flight while solving the problem of static air pressure perception.

The relevance of the work lies in the fact that altitude and speed parameters measuring accuracy requirements are increasing as related to their metrological characteristics, reliability and performance improvement. The situation is due to the need to meet mobility requirements, to ensure flights regularity and flight safety in conditions of vertical separation reduction. The vertical separation can be reduced only after the problem of the absolute barometric altitude measuring accuracy improvement is solved. But this requires the information channel altimetry revision and improvement. Due to the fact that the absolute barometric altitude is a function of the static pressure and airflow temperature, then applied to the scientific problem solved, the particular problem of above mentioned primary air parameters measurement accuracy improvement comes to the fore. In the article the results of on-board airflow static pressure measurement accuracy improvement possibility research are given.

As the main instrument in the course of simulation SolidWorks and ANSYS software packages were used. With the help of this software the instrumentation channel static pressure accuracy characteristics of different pitot-static tubes (standard and several examples of pitot-static tubes under development) at the altitudes of 5,000, 10,000 и 15,000 m at airflow to Mach 2,2 with the angle of attack to 30 degrees were obtained.

The results of standard pitot-static tube and pitot-static tube under development comparative analysis are given. The design modifications of the pitot-static tube under development static pressure chamber intake ducts are demonstrated.

The obtained results can be used for designing the on-board pitot-statiс tube with minimal errors in the measurement channel of the static pressure in a wide range of altitudes, velocities and angles of attack. This allows to recommend the proposed pitot-static tube for maneuverable aircraft.

Keywords: relative aerodynamic error, simulation modeling, altitude and speed parameters, pitot-static tube, static pressure

Recently, aircraft scheme mini — and micro- unmanned aerial vehicles (UAV) are considered to be a new promising direction of advancement of UAV. The increased interest in this class of aircraft is due to simultaneous appearance of new advances in the aircraft components miniaturization and new concepts of such devices application.

The purpose of the present study is to design and to solve small size unmanned aerial vehicles airfoil optimization problem for better performance. Analysis of obtained results and conclusions for further research are presented.

In the presented paper method of direct numeral airfoil optimization is used. As far as the method of direct numeral airfoil optimization implies the calculation of airfoil flow and airfoil performance, the calculation method (aerodynamic model) considers the aspects of airfoil flow at low Reynolds Numbers due to laminar-turbulent transition and separation bubble. Additionally this method and used technique is economical and efficient. Xfoil code is one of the few aerodynamic models that solves viscous-inviscid interaction problem in airfoil analysis.

So called genetic algorithm was used for optimization process. Genetic algorithm refers to stochastic method of numerical optimization.

In case of multiobjective optimization the method, based on homogeneous criteria comprising to one overall (integral) criteria was used. This method involves sum of criteria weighted by coefficients drawn up according to relative importance and other weights. It is so called weighted sum method.

Examples for numerical calculations of the airfoil optimization process using direct numerical method for one or more objectives at low Reynolds Numbers are presented. It was shown, that in order to design practical airfoil the optimization process should be multiobjective.

Numerical results in application of small size aerial vehicle were obtained, some important notice and conclusions was made, necessity and practical value of multiobjective approach were shown.

Keywords: airfoil, direct numerical optimization (DNO), small size unmanned aerial vehicles, low Reynolds numbers

When the pilot flies at medium and low altitudes in adverse weather conditions, he can make downward maneuver that cannot be completed without crossing a dangerous height (dangerous height is height below which the collision with obstacles is very probable). Necessity for monitoring of dangerous height increases the load on the pilot and diverts him from performing a specific task. So the efficiency of implemented task is reducing.

The object of article is to create an autorecovery system, which would allow to fly without focusing attention on the control of dangerous height.

At the present time there are the ground collision systems based on the prediction of the aircraft trajectory and the formation of a safe corridor. Using these systems for highly maneuverable aircraft is limited because of their ability to perform intensive and low predictable maneuvers. Also, there are the ground collision systems based on calculation of a altitude which is lost during the execution automatic recovery maneuver. This height is calculated as a function of the motion parameters. The disadvantage of these systems is that the loss of height is determined at the time of inclusion of the automatic recovery and not taken into account changes in the permissible and available g-loads that may occur during the recovery maneuver. Some algorithms do not use the maximum possible g-load on current fly mode. As a result, the area in which the «Recovery» mode intervene in the control of the aircraft increases.

The paper proposes a system based on integration of simplified differential equations of aircraft motion. The system consists of trajectory and velocity prediction block, model of pilot actions, and the aircraft model. This approach makes it possible to predict the height of the completion of the recovery maneuver and other aircraft motion parameters. These parameters are taken into account in determining the permissible and available g-loads during the recovery maneuver, which increases the accuracy of the system. A command occurs when the height of completion recovery maneuver is equal to dangerous height. Recovery maneuver consists of a roll to wings level combined with a pull up at 5g or the maximum available.

Result of the work is improving the safety near the ground. As a result of the paper the parameters of the proposed system for the MiG-29 K(KUB) is defined. A mathematical modeling has showed the acceptable performance of the system.

Keywords: autorecovery system from dangerous height, prognosis of height , of completion recovery maneuver

Research area of work is large folded mechanical systems tests. During the on-ground tests it’s necessary to reduce gravity force activity on joints of mechanical system. Zero-gravity systems are usable for that purpose. Zero-gravity impact on test results and that may cause corruption of results.

Goal of research is entering of analysis of mechanical system dynamic that allows get information about mechanical system behavior, about working capacity, and set specification to developed test equipment for reducing its impact on test process. On test preparation stage analysis of dynamics is usable for finding of most effective test pattern. On test stage usage of suggested method allows effective test result analysis.

During execution of competitive work methods of analysis of mechanical system behavior in compliance with on-ground test conditions is done. Features of all main stages of modeling are defined, process of developing and verification of calculation model is done. Universal calculation models are composed. These models may be used for analysis of similar mechanical systems dynamic.

Work describes results of analysis of spacecraft solar array dynamic. Features of motion, main parameters of functionality and actual loads are defined with application of modeling on design stage. Most effective zero-gravity system for that test object is picked and specification for its key parameters is done. Calculation model successfully pass verification on test stage. Maximum loads in plane of weakness are defined with calculation model. Analysis of some test patterns for maximum loads definition is done and most effective pattern is chosen. Difference between computed value and test value is 5%.

Described method of analysis is applied for precursive analysis of test pattern in common time. Method is applied for test equipment design and also for large folded mechanical systems test. That will provide high quality of on-ground test in JSC “ISS”.

Keywords: spacecraft, ground experimental test, deployment dynamic analysis

The paper presents a search and selection methodology for preferred embodiments of product designs engineering solutions meant for discrete engineering production capabilities. As methodology tools we use network and simulation modeling technologies. The paper also considers product, production process and production system models. Implementation of the methodology is shown by the example of aerospace products industry.

Method of solving this problem is based on the following assumptions:

1. The presented problem is a complex multi-objective problem; its solution requires a set of interrelated models of a product, manufacturing process, and production system. This is stipulated by the fact that the cost structure of the product includes all these categories;
2. The basic mathematical model for all three of these categories is a network model or network graph;
3. The order of models creation according to pp. 1, 2 is of great importance due to succession and inheritance relationships while transition from one model to the other:
4. Product model ^® Process model ^® Capacity model
5. Revealed continuity and interrelations, do not only allow provide manageability of the process of engineering options selection in terms of reducing production costs, but also give rather sufficient prerequisites conditions for extensive automation of these activities using of object-oriented programming principles.
6. Solution of the problem is a phased, iterative, time-consuming process, according to which «rough» and unsatisfactory variants are primarily sifted out.
7. Solution of the problem requires information support in the form of databases and software implementation of the related algorithms. Thus, the task of creating a complex of software and information support of the process under discussion is up-to-date.

Solution algorithm:

— Product mathematical model development: graph of product assembly;

— Product manufacturing process of product manufacturing network model development based on the graph of the product assembly;

— Network model analysis to identify critical and near-critical paths of the network model of product manufacturing process;

— Identifying «critical» processes that define found critical and near critical paths of the network model, as well as structures that will be subjected to changes.

— Development of engineering options of the obtained solutions;

— Development of products manufacturing production process variants network models;

— Analysis of the production lead time;

— Development of resource network models, allowing taking account of production capacity constraints;

— Analysis of resource network models, selection of a preferred embodiment according to the criterion of the smallest value of the production lead time;

— Development of a production system simulation model based on the selected variant of the resource network model to account for the organization component and market volatility situation: of production operation mode, portion nature of production, and production disruptions;

— Developing a model of market conditions impact on products time of delivery.

Keywords: concurrent engineering, manufacturing engineering, production systems, aerospace industry, simulation model, discrete production engineering, network model, graph.

«Millimetron» Space Observatory with the space telescope 10 meters in diameter is meant for study objects in the Universe at millimeter and infrared wavelengths [1].

The study of space telescopes analogues all over the world gave the following variants of mirror design:

— waffle structure with ribs in the form of a combination of triangular and pentagonal elements (ASC LPI them. Lebedev RAS) [2];

— sandwich made of composite material with triangular ribs (Planck telescope) [3];

— silicon carbide waffle structure with ribs in the form of triangular elements (Herschel Telescope) [4].

This paper considers design and manufacturing of the mirror based on composite materials. The main problem of implementing composite materials for highly-stable sizes design consists of synthesis of the material, its qualitative and quantitative composition, as well as reinforcement structures to ensure minimum thermal deformations at a certain level of stiffness and strength characteristics [5].

Thus, one of the objectives of this work lies in selection of optimal composite material reinforcement structure of reflecting surface. All calculations were carried out using finite element method.

Another problem of this work lies in selection of central mirror optimal ribbing structure. We considered various variants of the central mirror design, and carried out modal and static analysis for each variant. From this analysis, we selected the central mirror design, satisfying the specified requirements.

Further, we carried out product design and production engineering solutions for central mirror manufacturing. As a result, we selected central mirror sector-manufacturing technology that combines thermal compression and vacuum autoclave molding using a unique equipment. A feature of this technology lies in the fact that sector shaping is performed in one technological cycle. Raw stocks of all materials for all sector elements (reflecting surfaces, ribs, edges) laying out is carried out in in the raw state. Reinforcement ribs necessary shape are formed by an utility unit. The adhesive is not used in the design.

We made tests of this technology with the pattern corresponding to the accepted engineering solutions for the central mirror. The results of the pattern manufacturing confirmed the efficiency of the chosen technology. Thermal vacuum tests confirmed stability of the pattern geometry.

Keywords: composite material, wafer construction, rubber punch, vacuum-autoclave molding

Thermal control system (TCS) is one of main spacecraft support systems. Development of TCS allows increasing mass and energy efficiency of a spacecraft. Therefore, the task of TCS improvement by means of employed in TCS heat pipes (HP) efficiency increasing becomes more and more up-to-date. One of HP efficiency increasing methods means application of special types of HP, which are capable to regulate themselves a value of a transferred heat current. That means that HP is able to change one of its key parameters – the value of transferred heat power during HP operation in the preset temperature ranges. Such type of heat pipes are called variable conductance heat pipes (VCHP).
A breakthrough in the field of VCHP took place at the end of the 80-s of the last century when loop heat pipes (LHP) that outperformed, in many ways, conventional HP appeared. Conductivity regulation in VCHP is carried out by means of either mechanical regulators, or electric heaters, or thermo-electric modules. While wide technical capabilities are provided by rather complicated manufacturing technology characterized by long-term experimental development accounting for VCHP's high cost.
The paper presents design of gas control variable conductance HP, i. e. gas-controlled HP (GCHP) GCHP is an alternative to LHP widely used at present for TCS of modern unpressurised SC. The task of such facilities design seems quite up-to-date, as far as gas controlled VCHP application will allow to increase reliability of autonomous TCS, shorten production time and reduce cost.
Comparative analysis of VCHP state-of-the-art developed by Lavochkin Association is presented in this paper. Also other possible options of alternative VCHP application for SC thermal control are offered.
Algorithm of VCHP developed on the basis of application of capillary structure with axial grooves is offered. Methodology of main design parameters for VCHP with axial grooves determination are presented.
A version of simplified engineering calculation method of variable conductance HP adapted for gas-controlled VCHP with axial grooves is considered. Design of gas-controlled VCHP prototype and results of its testing confirming possibility of application of simplified engineering method for designing such devices is presented.

Keywords: heat pipe (HP), variable conductance heat pipe (VCHP), gas-controlled heat pipe, loop heat pipe (LHP), thermal control system (TCS)

It is possible to use the considered method of statistical processing of the random vibration process (RVP) for the solution to the four application-oriented tasks.

1. Measurement of random vibration process on mobile objects in installation sites of the onboard equipment of its accessories of elements. Mathematical processing of the records of RVP received in the case of a large number of experiments. Research on the RVP statistical parameters characterizing its temporal frequency and energy state.

2. Analytical formation of energy spectrums of RVP. Creation, as a base for statistical characteristics of RVP, the generalized energy spectrums reflecting for some time frame the energy and spectral state of RVP in separate points of sampling, in dynamic zones of mobile object and object in general. Unification of energy spectrums, their representation as recommendations for tests of the onboard equipment for influence of RVP, and bringing these recommendations about a measure of accumulation of statistical material to the level of standard norms of tests.

3. Formation of an energy spectrum on test bench of random vibration. Development of test methods for detection of the onboard equipment reaction to the RVP influence.

4. Research of dynamics characteristics of shock-absorbing systems in case of RVP influence. Study of different mechanical models of shock-absorbing systems and devices. Detection of optimum diagrams of arrangement of the elastic and damping elements for obtaining the best parameters of vibroprotection for the onboard equipment. Research in high-frequency area of dynamics of shock-absorbing distributed parameter systems. Creation of amplitude-frequency characteristics of vibration isolation for different mechanical models.

Keywords: random vibration process, statistical model, averagings, energy spectrum

Purpose

This paper deals with the choice of the design parameters of the pressure stabilizer (STP) ensured persistence of output pressure. The STP scheme that was designed is single-stage with slide valve pair.

Objective of this study — experimentally determine the nature of influence of hydraulic characteristics of inlet and outlet line on the output parameters STP, check the correctness of the design calculations and design decisions taken on 4 prototypes STP.

Design/methodology/approach

In the design process of STP the engineering calculations were carried out, which allow:

1) for a given stationary operating conditions to calculate the basic design parameters of STP,,

2) to evaluate influence of hydraulic characteristics of inlet and outlet lines on static characteristics of STP.

On the basis of these calculations 4 prototypes STP has been designed and manufactured and then tested. Tests have shown that the calculation results have good agreement with the experimental values. This proves the correctness of the used methodology. Method of STP calculation was used to develop a mathematical model to determine the parameters of STP for dynamic conditions.

In addition, the nature of influence of inlet and outlet lines on the static characteristics of STP was experimentally defined.

The tests do not simulate the stabilizer in the composition of the engine. In this case, the STP considered as a static object.

The tests were carried out on a hydraulic rig.

Static characteristics were recorded for four schemes:

1) scheme № 1 — «stabilizer + input pipeline+ output pipeline»;

2) scheme № 2 — «stabilizer without stand pipeline»;

3) scheme № 3 — «stabilizer + input pipeline + output pipeline + drain pipeline»;

4) scheme № 4 — «stabilizer + drain pipeline.»

Findings

1. The experiments confirmed the correctness of the calculations and design decisions taken.

2. It is shown experimentally influence of the hydraulic characteristics of inlet and outlet mains (input, output and drain pipe) on the level of static characteristics. It has been established:

— The level of the output pressure in the presence of pipelines connected to the STP higher than the output pressure level in the absence of in the connecting pipes STP;

— The drain pipeline has greatest influence on the value of the output pressure;

— Increasing the inner diameter of the outlet pipe of STP with d_y = 6 mm to 8 mm (assuming that the input and the drain pipes are also present in the test circuit) reduces the range between low expenditure (л/с) and high expenditure (л/с) characteristics;

— Used in these tests inlet and outlet hydraulic lines with desired characteristics can not affect the performance of STP i.e. it do not affect the stability of the process of pressure stabilization.

Practical implications

Experimental research methodology has been developed; it facilitates the design of similar stabilizers.

In addition, this design of pressure stabilizer is introduced into production.

Originality/value

The value of a given work is to auto design single-stage pressure regulators.

Keywords: liquid reactive engine, liquid reactive engine pressure regulators, control units, design pressure regulator liquid reactive engine

Among the autonomous high efficient energy sources for aeronautical and space purposes the aluminum-air (AA) chemical current sources (CCS) stand out as being of low cost, high theoretical energy density, accessibility, safety and environmentally friendly of the electrode materials.

However, in spite of a lot of research doing under the AA CCS their industrial production has not started yet. It concerns a lot of serious obstacles connected with aluminum anode, which have to be solved during the developing of the AA CCS.

The ways of increasing the energy and operation characteristics of the AA CCS have been analyzed and predicted in this work, with subject for over wide the fields of its application and functional possibilities. There are also a lot of experimental results in this work, namely polarization and corrosion characteristics of several aluminum anodes in alkaline and saline electrolytes with the different inhibitive additives (the corrosion inhibitors in the alkaline electrolytes, polymer coagulants which are modifying an aluminum hydroxide gel in the saline electrolyte).

It’s also shown that in AA CCS it is possible to use an industrial made protector alloy AP4N (Russian alloy classification) as an alternative anode towards an experimental especially developed aluminum alloy Al-In (created in MAI with subject for increasing energy characteristics of AA CCS).

As the corrosion inhibitors in alkaline electrolyte for AA CCS with a small rated power the salt of the organics acids can be used, for instance the sodium citrate. Addition of the coagulants based on polyacrylamid into the saline electrolyte has led to modifying of the aluminum hydroxide gel structure, which substantially simplify the usage of such current sources.

In this paper the research results in a hydronic CCS with aluminum anode are also shown. The hydrogen evolution reaction from the water occurs on the cathode in hydronic CCS. Authors have considered this CCS not only as a source of electricity, but also as an electrochemical regulated hydrogen generator for oxygen-hydrogen fuel cells, which makes it possible to increase the functional possibilities of the CCS with the aluminum anodes.

Keywords: chemical current source, electrochemical cell, hydrogen generator, polarization characteristics, corrosion characteristics

Currently, one of the urgent problems of modern engineering practice is the problem of fuel efficiency. One of the solutions to this problem is to use the heat recovery. The key technology in this case is the heat exchanger (HE). One of the most important components of the designing of the HE is the method of a calculation. The purpose of the study is to develop and verify the three-dimensional calculation method of the HE.

The presented calculation method is based on the software package ANSYS CFX. The basis of the calculation is the method of the numerical simulation of RANS. As a model of turbulence there is the SST model. Basing on the criteria dependencies of the Nu (Re), the verification of the three-dimensional calculation method was performed.  As a part of the verification a structured hexa mesh and an automatic tetra mesh were considered.  Both of the grids showed satisfactory results in the convergence of the experimental and calculation data. The discrepancy between the experimental and calculated data for Reynolds numbers less than 2000 for the hexa mesh was ~ 20% and in the case of the tetra-mesh it was 25-27%. At the higher Reynolds numbers the convergence of the calculated and experimental data is increasing: for the hexa mesh it is 1-8% and for the tetra mesh — 9-15%. As far as in a practice the creation of the structured hexa mesh takes more time, than creation of an automatic tetra mesh, the automatic tetra mesh was accepted as the most suitable option.

Considered technique is used to obtain a preliminary assessment of the heat transfer surface with the specified geometric parameters and operating modes of the heat exchanger. This reduces the design time and the cost of the full-scale tests.

Keywords: fuel efficiency, complicated thermodynamic cycles, heat exchanger

Physical and mathematical model, algorithm and software package for solving the problem of conjugate heat transfer between a viscous gas-dynamic flows and cooled gas turbine blades produced by means of a compound permeable shells technology are expounded. The mathematical model includes the dynamical and heat boundary layers equations, equations of the flow and heat exchange of air, in flowed from a power machine compressor, in complex channels inside the compound permeable shells (CPS), space no steady heat conduction in CPS skeletons, cooler injection in the gas-dynamic boundary layer, conjugate heat transfer between hydraulic gas dynamic flows and CPS construction.
Flow and heat exchange of the cooler are expounded in detail in each of seven typical CPS zones, which are essentially differ in a heat exchange level and accordingly in heat pick up from hot walls. The effective method permitting to define temperature fields by means when coordinate lines go out from a computational area in gas cavities and again get into the cavities with extraction of complex boundaries and putting fractional space steps on it was suggested for numerical solving of conjugate heat exchange problems in multiply connected space areas. The software package SPO was developed on programming language FORTRAN using modular concept permitting to expand functional possibilities adding new modules. Huge number of results in heat flows and space temperature fields in the elements of CPS were obtained using SPO. Efficiency of SPO was tested in cases of different rates of cooler flux and different heat flows caused by high temperature gas-dynamic flow (up to 2000K).
It was revealed, CPS take middle place between porous and perforating refrigerating in cooling efficiency, however, it is too difficult technologically to make a porous skeleton. Researches showed the cooling efficiency with applying CPS is great deal higher in case of small heat flows caused by hot gas. Also it was determined, in case of big rate of cooler flux, starting from 0,1 g/s and higher, the efficiency does not rise, i.e. it is possible do not increase the rate of cooler flux. It was showed, in a case of minimum rate of cooler flux ~0,1 g/s the CPS skeleton temperature reaches 400C when the gas-dynamic flow temperature is 1600K, that decreases strength of CPS skeleton considerably.

Keywords: compound permeable shells, gas-dynamic flow, conjugate heat transfer, conjugate heat transfer, heat flux, cooling efficiency, special software, boundary layer

Object: the object of the research is dynamic characteristics of the three-layer round symmetric plate with isotropic filler.

Topic: the research of impact interaction of three-layer round symmetric plate with isotropic filler.

Aim: to examine the influence of various factors on the dynamic characteristics of a three-layer round symmetric plate with isotropic filler during its vertical fall on liquid.

Research method: dynamic characteristics of a three-layer round symmetric plate with isotropic filler were numerically investigated in the software complex ANSYS AUTODYN, the permitting equations are equations of conservation of energy, momentum and mass. The solution is  carried out by explicit method. The task is placed in the axisymmetric formulation of coherent, i.e. equations for plates and liquid are solved simultaneously. The obtained results are processed in software complex MathCad 14.

Results: as a result of the work there are obtained the dynamic characteristics of a three-layer round symmetric plate with isotropic filler when it hits the water with different initial velocity of interaction taking into account the gravitational forces, the air gap and without.

Conclusions: the numerical experiment without the air gap shows that the dependence of hydrostatic pressure from the initial speed is linear. The effect of air gap causes oscillation plate and the surface of the water, which leads to the uneven of their interaction and significantly affects the value of the maximal pressure, however, with the increasing speed of interaction the effect of air gap is reduced. Stresses in the filler are in ten times less than stress in the carrier layers, which allows to use more light and less durable materials.

Keywords: impact, round plat, interaction with liquid, numerical simulation

Physical, mathematical and numerical models of the problem of a flat wall probe in the shape of oblong rectangular, engulfed by parallel to its surface flow of weakly ionized plasma were developed.

We carried out full-scale computational experiments resulting in obtaining theoretical values of current density versus probe typical size r₀, its potential φ₀, directional velocity of a dense weakly ionized plasma u₀, ions and electrons temperatures ratio ε, parameter D₀, that characterizes orifice gas molar mass.

Non-linear end and edge effects and their impact on probe current density were studied. The studies show that probe current density at reasonably large negative potentials (φ₀ < —40) and probe typical sizes (r₀ > 50) exceeds minimal limit value, practically irrespective of parameters of the problem.

Obtained ion saturation current limit value allows developing an original probe experiment methodology with its further processing. This methodology does not require availability of probe characteristics set, applicable for large probes of any geometric shape (disc, square, rectangle etc.), meant for application with streams of various molar masses. Probe experiment processing is simple and does not require complex computational algorithms application.

The suggested methodology may be useful for probe experiment results processing with GLA, as well as dense weakly ionized plasma jets, flowing out of different purpose plasma jets.

Keywords: electric probe, probe experiment, flat wall surface probe, continuity equation, Poisson equation, finite effect, edge effect

The destabilization of stable equilibrium position of a non-conservative system with three degrees of freedom under joint action of potential, non-conservative positional forces and small linear viscous friction with complete dissipation force is considered. It is assumed that the system has an isolated equilibrium position.

The problem of the stability of three-link rod system under non-conservative tracking forceload in a horizontal plane is investigated. Tracking force applied to rigid body forms a constant angle with its axes. The rods are joined by viscoelastic spiral springs.

Stability of equilibrium position is studied in linear approximation using Lyapunov’s theorems. The coefficients of characteristic polynomial are constructed by using Le Verrier’s algorithm. They depend upon the invariants of the matrix of linear approximation equations. Zigler’s effect condition and stabilitycriterion were obtained using perturbation theory. The stabilizationregion and Ziegler’s area werebuilt in the parameter space with the help of computer algebra methods.

Using Lagrange equations of motion formulas for the coefficients of characteristic polynomial are obtained. Stability of three-link rod system’s equilibrium position is investigated when there is no dissipation. Zigler’s area and criterion for the stability of the equilibrium position of a system with three degrees of freedom, in which the friction forces take small values, are constructed.

The results of the study may be useful in stability analysis of a non-conservative system with three degrees of freedom, in particular, of the three-link rod system that can be used as a model of elastic rod.

Keywords: three-link rod system, tracking force, dissipative forces, asymptotical stability, Zieglers effect, Ziegler’s areas, stabilitycriterion

Purpose

Analysis of overhead transmission lines (PTL) consists in the solution of a number of problems associated with calculations of static states and vibrations of conductors and cables together with spiral accessories, vibration dampers and other attached devices on them. Their solution is only possible if the correct accounting bending and torsional stiffnesses of the wire structures. In some problems, these parameters are crucial, for example, associated with the development of energy security and reliability systems for information-telecommunication supply of aerodromes, aircraft and rocket systems, overhead transmission lines of general purpose, subjected to wind in different climatic conditions.

Analysis of the literature and the state of the art in this field of mechanics shows that there are not common methods that would allow simulating the deformation of such structures, to calculate their stiffness characteristics, load-bearing capacity, optimize design parameters. In this regard, the development of methods for the analysis of stress-strain state of the multilayer wire structures, each layer of which is formed of a spiral wires or their strands is actual and practically significant problem.

Design/methodology/approach

In this paper each wire layer is considered on the basis of the energy approach as equivalent to the elastic properties of anisotropic cylindrical shell and the wire structure as a whole is modeled as a system of nested cylindrical shells interacting by forces of pressure and friction.

Findings

Based on this approach, the formulas for calculation of flexible and stiffness matrices are obtained. The formulas for calculation of bending and torsional stiffnesses of the PTL conductors and cables are also obtained with regard to their internal structure and interaction of wire layers each other.

Research limitations/implications

Resolving equations for a wire layer are obtained in the framework of Hooke’s law without taking into account the possible plastic deformation.

Originality/value

The new approach is suggested to modeling the deformations of multilayer wire structures taking into account the layer interaction between each other.

Keywords: conductors of PTL, energy averaging, interaction of wire layers, bending and torsional stiffnesses

One of the main tasks when developing a strap-down inertial navigation system is creation of attitude determination algorithms providing both convenience of numerical realization of the algorithms, and minimization of computing errors. Attitude determination algorithms for strap-down inertial navigation systems and its error equations are considered in the paper. The main purpose of the paper is receiving the functional algorithms allowing direct calculation of aircraft orientation angles in the form of heading, roll, and pitch. It is specified that the use of Rodrigue-Hamilton parameters for orientation angles calculation do not give particular advantages compared to their definition with orientation matrixes. Qualitative differences of the suggested algorithm from the algorithm based on orientation matrixes are noted. The algorithm is convenient when using in the systems that requires calculation of angles of heading, roll, and pitch. The algorithm under consideration also can be applied when carrying out numerical or semi-natural experiments using rotary tables or motion simulators for inertial sensors and inertial navigation system characteristics research. The equations in variations allowing describe errors of strap-down inertial navigation systems in specified tasks are obtained in the paper. Variants of equations set down in relation to the movement along a loxodrome and along a great circle route are given. Dependence between projections of absolute angular rate in various coordinate systems is shown that is actual for various tasks of navigation and orientation of different mobile objects. Possibility of use of the suggested error equations both for platform or strap-down inertial navigation systems is noted.

Keywords: orientation algorithm, inertial navigation system errors

The structure of meteorological active-passive complexdeveloped by the authors is described. It determines the meteorological parameters of the atmosphere and cloudsby remote method.

The complex consists of the following measuring devices:
- infrared lidar determines the height of the lower border of the cloud to 7.5 km;
- lidar with linear frequency modulationevaluates the optical density of low-lying clouds and ground-level aerosol;

- infrared thermometer with scanningpartfixes radiation temperature of extended metaobjects.

The main parts of the complex are located on a common platform which automatically orients the measuring part tothree mutually perpendicular planes. The angular position is controlled by high-precision sensors inclinometer.

The operator can control the measuring complex from a remote locationby using the digital video camera for surveillance and Wi-Fi module for connection between the individual components.

Experimental datasare processed by a special program.It allows obtainingthe following characteristics: temperature and height of the lower border of the cloud, its water contentand liquid water content, the concentration of ground-level aerosol.

The complex is fully automated. Experimental datasare needed forshort-term forecast of development of the observed metaobject,as well as long-term weather forecast ina region. This development allows to obtain information about the object by remote method in real time. Mobile measurement complex can be used in various areas, including hard-to-reach.

Keywords: lidar radiometric system, lidar, controller, inclinometer, digital compass

Underwater vehicle's visual positioning system (VPS) is designed to determine its local motion parameters near object site. This article describes implementation of such system and its adaptation for small-size ROVs.

Using specially developed algorithms for video images processing the VSP processes video information obtained from underwater vehicle (UV) video camera. It allows to measure UV’s both cruising and lag coordinates and velocities, as well as its distance from the seabed which are used for closing feedback loops in motion control system.

Comparison of correlation-extreme algorithm, optical flow method and methods based on descriptors collating was made. As a result we choose modified Kanade-Lucas tracker (KLT), representing one of the methods for optical flow evaluation. We also consider it worthwhile to further study of binary descriptor-based tracker for VPS.

We adapted KLT for use with small-sized remote controlled ROV. To achieve this goal we increased frequency and conducted laboratory and semi-natural testing. Algorithm efficiency with trim and list angles up to 30° was experimentally proved, under condition of obtaining these angles values from external sensors. The absence of drift error of coordinates measured by VPS in length of time was also shown. Based on Bode diagram we came to a conclusion that visual positioning system can be represented as pure time delay link within the control system.

A full-scale tests of VPS on ROV in the special natatorium showed that developed VPS can be used for small-sized highly dynamic ROVs local positioning within object site. The represented video positioning algorithm can be also used for automated drone hovering mode.

Keywords: local navigation, video processing, underwater vehicle, control system, computer vision, image fitting, dynamic positioning

Flight mission planning systems [1] for various aircraft have a lot in common, and perform the same tasks. Therefore, the actual task is to develop unified software for such systems that could be quickly adapted to specific requirements of the particular technical specification. To achieve this goal, the hierarchical modular software architecture is proposed, where a «model-view-controller» concept [2] and other concept [3] are applied for the proposed architecture.

The following software subsystems are defined in the proposed architecture: cartographic subsystem (the first level), subsystem of navigation situation input (second level), subsystem of flight planning (third level), subsystem of flight data preparation (fourth level). Subsystems of a lower level do not depend on subsystems of a higher level. A concrete planning system can contain more than one subsystem at a certain level. Subsystems of higher levels are possible. A major module operate with major subsystems by a common template

Each subsystem consists of two modules: business logic module and module of graphic user interface. Business logic modules realize application environment models, application task kernels, read operation, and data processing and storage. While user interface modules determine dialog boxes configuration, logic of domain models (data) imaging, and semantic processing of user actions. The modules of business logic do not depend on the user interface modules. Pattern «Observer» is used to present notification concerning events (changes) within models at runtime.

If new customer wants to use another configuration of dialog windows then it is possible to develop new user interface modules while keeping existing business logic modules intact. Conversely, in case of domain algorithms changes (or significant changes in data access and processing), business logic modules can be replaced with minimal modification of existing user interface modules or keeping them intact. In addition, software partitioning in business logic part and the user interface part enables more efficient of developers abilities usage: some of them specialize in the development of domain models, and others concentrate on the development dialog windows.

The proposed architecture was implemented for one of flight mission planning systems developed by Ramenskoye Design Company. The developed software has passed certification and has been successfully implemented with some other systems.

Thus, we obtain the software platform, which further implementation and development can lead to significant cost price and launch date reduction of new products, and profit markup of an enterprise.

Keywords: flight mission planning system, software architecture, design patterns, design patterns, model-view-controller (MVC)

In order to increase the efficiency of the optical methods of the nondestructive testing of assembly units, equipment and component parts of the aerial vehicle of the Russian aircraft, the complex of statistical and natural tests on use of a method of speckle-structures of optical radiation and correlation analysis of images, for diagnostics of a status of surface and subsurface structure of aviation details was carried out.

During numerical and experimental studies it is established that the value of an interval of correlation of the registered speckle-pictures directly depends on the dimension of defect of the probed sample, the bigger the dimension of defect, then the smaller the interval of correlation of a speckle-picture. The limits of applicability of algorithms of correlation analysis of digital speckle-pictures for determination of parameters of roughness of the controlled objects are also defined, it is established that in case of registration of a speckle-picture by scheme using radiation transmitting through optical system (through sample material) the range of the dimension of roughness for which a method of correlation processing is applicable is about 4 times bigger than in case of reflection of wave front from a surface with the subsequent registration of a picture at once on a screen matrix. It is established that it is effectively to use the correlation analysis for determination of high-rise parameters of a controlled surface at the maximum height of roughness of hmax ≤ 8λ− for reflection and hmax ≤ 32λ − for a radiation transmission through a sample.

During an experimental study on application of the method of speckle-structures of optical radiation for an estimation of the internal structures of composite materials it was established that with the increase of the dimension of internal defect the value of the radius of correlation of the speckle-picture increases, and the width of the energy spectrum decreases witch is explained by a smaller transmission of laser radiation through the material in the area with a bigger diameter of the internal defect. In case of control of the optically nontransparent surfaces the inverse relation is observed, so the bigger the high-rise parameter of roughness or width and depth of the defect, the smaller the value of the radius of correlation of the registered speckle-picture. It is established that the most sensitive parameter of the registered speckle-pictures in using correlation analysis is the value of the radius of correlation of a speckle-picture.

Consideration of the features of realization of the method speckle-structure optical radiation in laboratory conditions and also the existing optoelectronics element base in use allowed to develop the model of the test mobile speckle-laser defectoscope. The software module which would allow to automate the process of defectoscopic control with the use of a method of speckle-structures of optical radiation is developed for the correlation processing of speckle-pictures with the use of the Qt tools, QWT libraries and the compiler GNU C ++. This software module carries out the following tasks:

— capture of a speckle-picture from a mobile defectoscope;

— definition of the speckle-picture parameter (radius of correlation and width of the energy spectrum);

— displaying information on the defect-free or malfunctioning of the controlled unit to the operator.

Thus, the hardware-software complex of non-destructive control allowing executing operations of defectoscopic control of aviation details and manufacturing conditions is developed.

The results of the work can be used for justification of tactical technical requirements on creation of devices of non-destructive control, which principles of operation are based on use of the method of speckle-structures of optical radiation.

Keywords: nondestructive testing, roughness, speckles, correlation

The purpose of this work consists in code creation for on-board digital signal processor of a medium-range guided missile. The program code must realize the specified missile guidance algorithm. Microprocessor has a limited set of debugging tools (system «input—output») and insufficient computing power for floating point data processing.

Approach

The offered technique implies the sequential transformation and debugging of the guidance algorithm in MATLAB-Simulink using «physical», «discrete» and «integer» models.

We use «Physical» model to receive control algorithm internal data in accordance with sampled test data.

Creation of «discrete» and «integer» models is carried out with allowance for specifics of the microprocessor computing environment. The «discrete» model helps to select formulas of numerical integration techniques for dynamic units implementation. Formula selection criterion is defined as the relation between its precision and execution speed, estimated by the tests of a microprocessor basic operations.

All variables and constants of guidance algorithm in «integer» model are represented as fixed-point data with limited bit length. To maintain correctness and precision of mathematical operations, normalizing binary shifts should be added to the model. These shifts operations exclude underflow and data bit grid overflow. Various methods of solution are applied to impart desired properties to integer dynamic units. They include adding of correction coefficients, the structural transformations of blocks, data allocation in multiple variables, reset of schemes and varying frequency of block solutions.

Tables with program-extensible domain in binary notation are used for calculating mathematical functions with finite range (sine-cosine). CORDIC‑algorithm is applied for calculation of the functions realizing rotation of a coordinate system.

The «integer» model is converted into C-code automatically or manually after confirming its accuracy.

The results, value and practical application

The proposed technique allows adapting computational algorithms for integer microprocessor systems in the absence of their standard debugger. The final «integer» model is optimized by precision and speed of data processing. Debugging and customization of program code are performed in a short time inside the language of technical computing MATLAB-Simulink without a microprocessor’s debugging tools. This technique is used in several products of JSC «KBP»; its effectiveness is confirmed by full-scale tests of guided missiles.

Keywords: guidance algorithm, digital signal processor, MATLAB, modeling with Simulink, discretization, fixed point data, methods of discrete-time integration, data scaling, CORDIC algorithm.

The urgency of developing new approaches to the design and producing of a new generation of early warning radar is stipulated by the contradiction between increasing requirements to the characteristics of a new generation of early warning radar and the development of basic breakthrough technologies for their creation.

Developed by JSC “RTI” methodology for creating an early warning radar of a new generation provides initial decomposition of design specifications imposed by the Customer into major functional tasks. Functional tasks represent the basis which is more stable and repetitive from generation to generation. It allows providing maximum continuity of performed functions during transition from one generation of products to another, and as a consequence increasing unification level of a number of early warning radars. And functional-algorithmic systems are formed on the basis of the functional tasks.

The proposed methodology peculiarity lies in the fact that we introduce a new approach to the development of an early warning radar of a new generation. It is based on the design and implementation of a unified hardware and software design platform for radars.

For functional-algorithmic systems of an early generation radars development, hardware and software functional components (blocks, modules) testing, as well as evaluation of deviation scope of current values of blocks and modules characteristics from those requested by the JSC “RTI” Customer the General Designer test bench was designed. It represents the main and uppermost interlink between theoretical development and practical implementation of the stations.

Let us represent the radar development as a complex multivariate process subjected to variable and often unpredictable effects of different events, a full description and formalization of which is extremely difficult.

The aforesaid formalization is possible when using the methodological apparatus of mathematical statistics, which allows operate with generalized concepts and highlight the most significant risk factors that affect the simulated process characteristics.

The represented event model advantage lie in the fact that the ability to implement operational management of the processes of development of a radar based on joint analytical treatment of the theoretical and experimental results of the process of creating the radar at all stages of the life cycle of its the creation. The deviations of requirements to module parameters from tactical and technical requirements are recorded with General Designer test bench and compared to predetermined characteristics of the functionally-parameter matrix. Deviation of measured parameters is converted to values of the modules readiness factors, which are used for calculations and risk operation monitoring.

Using mathematical event model expressions it is possible to calculate risks of an early warning radar development, successively evaluating modules parameters with General Designer test bench. And according to obtained data take reasoned decision on the necessity of selecting some other module in the case of its nonconformity to performance characteristics.

The presented method formed the basis of mathematical and software development for an early warning radar automated system (ASC) design. One of the main requirements to the ASC, was JSC "RTI" design works management methodological reserve buildup, which fundamental component is General Designer test bench. Efficiency upgrading of working process by th implementation General Designer test bench should lead to radical improvements in design timing data and adjustment of the station systems.

Keywords: early warning radars, design methodology, risk, mathematical model of the design process, readiness of the project

At the present time to effectively control the aircraft are used in communication systems to interact not only with the ground control, but also for data exchange between aircraft. Each aircraft is both the source and relay messages. An important feature of the data network in this case is the dynamic change of network configuration and no external configuration mechanisms. It should also be noted relatively small lifetime of the network in the same configuration.
Communication network providing communication between mobile objects with dynamically changing configuration has been termed adaptive networks

The proposed work deals with the problem of analysis of control algorithms that ensure high network efficiency based on the analysis of only local parameters that each node can determine yourself.

The paper discusses four methods of managing network random access to puncture synchronous Aloha. Analysis of management methods is based on a simulation model.
The first method takes into account the average network traffic and the number of nodes in the network. For each value of traffic and the number of nodes is determined by the optimal repetition period.

The second method uses to change the repetition period of the current number of retransmissions. When it reaches a certain level, the period increases with each new re-transmitting the packet. In case of successful transmission of the repetition period is reduced. For this method, the optimum rate of increase and decrease of the repetition period and the threshold for the number of retransmissions.

The third method uses to change the repetition period of the current network load. In the case of distortion of the package, the repetition period is increased to an appropriate current load limits. This limit value of the repetition period is determined from the condition of ensuring the minimum transfer time is only possible for this network the number of nodes. For a successful packet transmission, the repetition period is reduced.

The fourth method is a combination of the second and third methods of control. When the distortion of the package, the repetition period is gradually increased, but only up to the boundary values.

The simulation results show that in the whole range of traffic and the number of nodes the best features of the fourth, the combined method of control. Amongst the top three management methods at low and medium traffic is the second best method of control, and at high traffic and a large number of nodes, the best is the third method of control.

Keywords: telecommunication technology aircraft systems, aviation systems and data communications, intelligent network management, random multiple access

Modern aviation communication system based on the modular principle with the use of open architecture. For this class of networks characteristic is the constant change in the number and composition of concurrent mobile objects, a significant limitation on the time of network access and the use of relatively low-speed data channels. A certain compromise of conflicting requirements to the network is the use of the protocols of random multiple access, in particular, Protocol synchronous Aloha.

In the present work we study the behavior of the network under heavy load. Interest in this problem stems from the fact that due to the limited frequency resource growth in the number of mobile objects leads to a corresponding increase in network traffic. Thus the probability of the transition network in an unstable condition characterized by a significant deterioration in the efficiency of its functioning. With the aim of improving the operational characteristics of the network it is necessary to clearly identify the current state of the network and to predict its transition to an unstable state.

In this paper an attempt is made choice of such control parameters whose values allow to detect the access network from the steady state.

For a detailed analysis of the characteristics of the network developed a simulation model that allows to investigate the behavior of the network under rather General assumptions.
The simulation results show that the transition in unstable condition leads to a qualitative change in the distribution of the transmission time of a packet. A small number of nodes and traffic characteristic of the steady state, the density distribution has the form of a normal distribution. A large number of nodes or high traffic, typical of the transition network in an unstable condition, leads to expansion of the density distribution, the graph of the function becomes flatter. Thus, the type of density distribution allows us to estimate the number of nodes and network traffic, as well as the degree of closeness of the network to transition to an unstable state.

Qualitative changes in the distribution of the transmission time impact on the behavior of the moments of the distribution. It is shown that the coefficient of variation of time the packet has a critical value of the order of unity. The critical value indicates the transition network in an unstable state.

The obtained results allow to choose the parameters of the network management for the timely prevention of the transition it into an unstable state.

Keywords: telecommunication technology aircraft systems, aviation systems and data communications, intelligent network management, random multiple access

This paper discusses the design of the probing signal generator for spaceborne Synthetic Aperture Radar. Spaceborne SAR systems operate in conditions of interference signals influence (range and Doppler ambiguity, blind zones, etc.). The correct selection of pulse repetition frequency (PRF) of the probing signal allows reducing influence of noise on the echo-signal. In order to reduce the noise influence, the FPGA-based signal generator for spaceborne SAR is proposed.

Onboard memory blocks are mostly affected by space radiation (heavy charged particles). For this reason instead of Memory-based architecture an algorithm based on the Direct Digital Synthesizer architecture is presented. To increase the sampling rate up to 480 MHz the method of parallel processing is used (four 120 MHz channels for each I and Q quadrature).Thus achievable bandwidth equals 400 MHz (20 percent less than sampling rate), that allows to provide range resolution about 1 m (orbit altitude 514 km, angle of sight 20 degrees).

The special algorithm of PRF calculation is used. This algorithm takes into account blind zones distribution and nadir reflections on PRF – angle of sight plane. PRF values for the whole range of angles of sight are stored in FPGA memory.

The initial data for the signal generator are angle of sight, duty cycle and bandwidth. Angle of sight determines the working value of PRF. Duty cycle and working value of PRF determine the duration of the probe pulse. Bandwidth provides the required range resolution. Thus the probing signal generator provides desired characteristics of probing signal.

Keywords: synthetic aperture radar, programmable logic integrated circuit, digital signal processing

The development of modern radar systems in the field of aviation and space exploration is inseparably linked with the use of complex-modulated sounding signals. The object of study in this work is complex phase-code manipulated signals. The technical result of the work aimed at improving the performance of modern radar systems, such as resolution, speed and range of analytic detection range. Scientific novelty of the work lies in the proposed method of processing of probing signals. The aim is to develop a method for spectral processing of additional signals, alternating in time, eliminating the influence of the Doppler effect on the side-lobe level of the processing result.

The paper discusses detailed analysis of the influence of the Doppler effect on the agreed process additional signals considered by the example of the total treatment, developed a method of push-pull spectral processing additional signals, which eliminates the influence of the Doppler effect on the treatment result, a closer look at the device, based on the claimed method. It is shown that the industrial applicability of the proposed method is possible due to the fact that all the operations used in the feasibility of digital technology and software in the computer technology. The use of the method satisfies the conceptual design technology features modern radar systems in the field of aviation and space exploration.

Keywords: radar system, resolution additional signals, additional signals, side-lobe level

This article presents the results of the development of the new quasi-coherent QPSK (quadrature phase shift keying) signal modulator structure, compared to traditional schemes of quasi-coherent QPSK signal former it has complex of improved parameters: increased locking range and holding range, the minimum synchronization time, improve accuracy and stability of the manipulation phase in the presence of destabilizing factors affecting the parameters of the device.

In the article, it is shown a block diagram the device. The description of the operating modes are given. Phase portraits of the device, timing diagrams of transient processes for mode of initial synchronization and mode of synchronous operation are shown. The results of the device simulation in MATLAB / Simulink are presented.

The dependence of the frequency synchronization time on initial frequency detuning were obtained for developed device and QPSK signal modulator based on traditional phase locked loop (PLL) (transfer function described by a differential equation of order 2), in Matlab / Simulink.

The results obtained during the study show a significant extension of the locking range of the developed device compared to the considered conventional scheme of quasi-coherent QPSK signal modulator. Time frequency synchronization of developed device has also significantly reduced and slightly changed in the all considered range of frequency detuning. The new structure of quasi-coherent signal modulator QPSK presented in the paper are promising for use in practical applications such as the reference oscillations using signals received from distant sources of standard time and frequency scales.

Keywords: quasi-coherent modulation, QPSK modulation, phase portraits, timing diagrams of transient processes, simulation

This paper describes the perspective way to provide a subnanosecond accuracy of time scales checking is using a space optical laser location system. The application is satellites of GLONASS system or others and land stations with central synchronizers or other object with its own time scales used for the local purposes. The considered system consists of land and space segments. The land station provides short impulses of laser radiation (the wavelength is 532 nanometers, impulse duration less than 400 picosecond) in the direction to the spacecraft and registers exact time of start impulse and arrival time of an impulse reflected by the retroreflex system installed on a satellite. These measurements are made in a land station time scale. The space segment provides precision registration arrival time of a laser impulses in a satellite time scale. These measurements open a way to calculate time scales difference between a space satellite and land station.

The solution of perspective problems of precision checking time scales requires transition from nanosecond accuracy of measurements to subnanosecond accuracy. Optical laser location systems allow to solve problems of far located objects time scale synchronization with from tens to hundreds picoseconds accuracy. Such accuracy wasn’t reached by any other systems so far. This work is performed by the Federal program «Maintenance, Development and Use of GLONASS System for 2012-2020», the customer is a Defense Ministry of the Russian Federation.

Keywords: optical laser location, precision time measurement, time scale synchronization