Volume 24, Nº 1 (2025)

A method for evaluating the mainline aircraft center section weight efficiency based on a mathematical model of a deformable solid body of variable density was developed. The criterion for the evaluation of structure weight efficiency is the dimensionless coefficient of the force factor assumed by V.A. Komarov. It is revealed that the maximum structural height of a theoretically optimal wing-to-fuselage connection elastic system in the horizontal plane of symmetry of the fuselage is equal to the half of the bending moment transmission length in the connection. The geometric characteristics of the wing-to-fuselage connection were obtained, allowing the realization of engineering solutions with a significant mass reduction in comparison with the constant structural height center section. The sensitivity analysis of the force factor coefficient is performed for different positions of the upper boundary of the design area.

An analysis of the factors influencing the target characteristics and the required characteristic velocity during an orbital maneuver to improve the target characteristics of small spacecraft is presented. The analysis was performed for the AIST-2 type small spacecraft in orbits with an altitude in the range from 350 to 700 km, taking into account the angle of deviation of the optical axis of the spacecraft. To estimate the active life of the AIST-2D spacecraft, changes in air density caused by solar activity during the spacecraft’s orbiting are taken into account. In order to ensure the active life of the AIST-2 typesmall spacecraft for more than 10 years, and taking into account the fact that the target characteristics are the most stable as soon as the spacecraft descends to a certain height, the engines are started to maneuver the spacecraft to its initial height. The required characteristic speed is obtained from the height difference of the orbit that must be re-raised to solve the task of monitoring Myanmar’s territory, and based on this value, the required fuel mass, the mass of the propulsion system and the most suitable engine type are determined.

A method is proposed for monitoring the performance of spacecraft payload in real time. The method is based on analyzing of the equipment state and sensor readings, and detecting unlikely rare combinations of the recorded parameters as potentially dangerous for the equipment. It is noted that the method is universal, that is, it can be applied to any type of controlled parameters, regardless of the method of their registration and physical dimension. Also, the method does not require preliminary calculation of maximal values (thresholds) for the controlled nodes. Specific examples are considered based on the data obtained during the operation of spacecraft equipment and during scientific space experiments. The results obtained can be used to increase the active lifetime of spacecraft, including multi-satellite constellations and CubeSat-type devices.

In the production of aircraft engine parts, methods that allow detecting surface discontinuities in the material are widely used in testing operations. One of these methods is the capillary method of non-destructive testing. To solve one of the specific tasks – detection of contamination on the inspected surface, a description of the method for searching for defects on the surfaces of gas turbine engine blades under visible light is presented. The solution to the problem of searching for contamination during inspection of blade surfaces is based on image segmentation using the U-NET convolutional neural network. The results of using the trained model on blades in the production units of PJSC “UEC-Saturn” are presented.

An experimental method for studying the natural vibration modes of the acting faces of large-sized optically-transparent components used in the imaging and interference systems in optical-electronic sets is proposed. Based on a noise-proof digital pattern speckle interferometer, an optical system was developed to provide the registration of the normal component of the vibration displacement vectors on the flat optical surface with the deposited diffusing coating. The optimal transmission of the coating was determined for recording the contrast speckle-interferograms. The vibration modes of the flat, diffusing element included in the digital speckle pattern interferometer are investigated in order to verify the results of numerical modeling of its vibrations at resonant frequencies. For natural vibration modes recorded in the range from 0 to 900 Hz, deviations between experimental and numerical results within 5…7% were found.

An analysis of the design features of a system for supplying granular propellant to the rocket engine combustion chamber was carried out and requirements for this system were formulated. The closest analogue is considered – the aluminum powder supply system of a jet engine. This supply system provides a critical flow mode for the powder-gas medium, at which the processes occurring in the combustion chamber do not affect the granular propellant supply. The disadvantages of this supply system are listed, provided that it is used in a granular-propellant engine. An engine schematic diagram was developed, as well as a control unit for the propellant supply system as part of the propulsion system that fully satisfies the stated requirements. An experimental setup for the powder-gas medium (granules and gas) outflow studying was designed, the operation of the setup was described in detail and a design diagram was given, in particular, a propellant tank and a flow control unit. Some design solutions used in the experimental setup can be subsequently used in the real rocket engine design. Based on the theoretical and experimental data available in the literature, the problems solved using the developed installation are formulated: obtaining flow and velocity characteristics of the critical outflow of a powder-gas medium as a function of the pressure in front of the outlet.

In the presented work, the calculation of critical rotor speeds and determination of vibration characteristics of an advanced gas turbine engine are considered. The engine under study contains a low-pressure compressor with an elastic damper support of a new design that has non-linear characteristics of stiffness and damping coefficients. The problem of creating a model of elastic damper quasi-linear supports of gas turbine engine rotors is solved by adding a quasi-linear element to the dynamic calculation model created by the DYNAMICS A4 software system. The parameters of the element change their values depending on the rotor speed. The task of verifying the results of experimental data is investigated. The presented technique makes it possible to build a quasi-linear model of the rotor support and ensure the coincidence of calculated and experimental data.

The paper presents a comparative analysis of existing milling technologies. The influence of the main negative factors affecting the quality of machined surfaces is revealed. Optimal schemes for machining with opposed cutters are proposed. The modeling of milling processes with oppositely located cutters of thin-walled extended aircraft parts is carried out. The process under study is described by the appropriate physical quantities. A system of eight characteristic equations describing the modes and components of cutting forces, as well as the dynamics of the milling process, is considered. A characteristic equation in dimensionless form is obtained, linking the geometric parameters of the cutting tool, the feed rate and the rotation frequency of the cutter. After checking the synthesized mathematical model by calculation, an experimental check of the proposed model for adequacy to the real process was carried out when machining the appropriate walls of blanks of ribs and beams made of aluminum alloy, manufactured by stamping, with oppositely located end mills. The edges of wells and pockets of aircraft parts were machined in small-scale production conditions. Roughness measurements were taken using a profilograph-profilometer. Optimum values of exponents and appropriate coefficients for simplexes of the mathematical model were determined. A comparative analysis of practical indicators and simulated data of the milling process was carried out. The resulting model allows predicting the results of machining by the proposed method with an error of 10…15%.