In this paper, the object of research is the icing of aircraft surfaces during flight in the atmosphere. On many light aircraft, as well as on unmanned aircraft weighing less than 30 kg, there are no on-board de-icing systems. Nevertheless, aviation events occur with these aircraft, which are a consequence of their icing. Therefore, determining the most dangerous flight modes of aircraft in icing conditions is an urgent task. In view of the high cost of conducting flight tests and the impossibility of covering all possible events due to their potential danger, the complexity of creating flight conditions for aircraft in icing conditions on the ground, the mathematical modeling method was used in this study. To solve this problem, the analysis of the airworthiness standards of civil light aircraft, transport category aircraft, rotorcraft of normal and transport category was carried out within the framework of the work, the influence of various parameters on the thickness of ice build-up was investigated using a computational experiment conducted on the software developed by the authors of the article. On the basis of the results of the computational experiment, the dependences of the ice thickness on various icing parameters were obtained, a method was developed for determining the combination of heights and flight speeds of an aircraft, at which ice of the greatest thickness is formed on the surface of aircraft, other things being equal. Possession of this information will allow the aircraft crew and air traffic control specialists to avoid the most dangerous flight modes in terms of icing. 

Modern conditions of economic activity of civil aviation operators make actual the problem of economically feasible measures for the organization of technical operation and maintenance of industry equipment, in particular, means of radio technical support for flights and aeronautical telecommunications. At the same time, it is obvious that these means need to be transferred to maintenance on a condition, which, in turn, causes the need to solve the problems related to determining the time for the preventive replacement of elements which diagnosable parameters can reach limit values. This paper presents an algorithm for estimating the optimal replacement of elements using the conditional probabilistic characteristic method for systems with a long period of operation and having a fixed number of failures. An assessment of the accuracy of determining the desired parameter is carried out, provided that its changes have deterministic and random components. The mathematical expectation and variance of the obtained estimate are found. Provided that the time of means operation between restorations (repairs) tends to decrease with an increase in the number of failures, the average number of final failures is obtained that satisfies the Volterra integral equation. To analyze the cost of restoration within the framework of the proposed model, an expression was found for the unit cost of work, depending on the accepted replacement rule and the duration of the expected cycles. Taking into account the mathematical expectation of the latter and associated costs, a two-dimensional optimal replacement rule is formed, and the expediency of using such a replacement period that minimizes the maximum average costs is shown. The obtained results are useful in organizing activities for preventive maintenance of radio technical support for flights and aeronautical telecommunications at various stages of their life cycle.

When conducting training sessions at an aviation university, it is advisable to demonstrate samples of aeronautical equipment, individual elements of systems and accessories, or use specialized stands and posters. However, when studying modern types of training aircraft, the cockpits of which contain multifunction displays, complications arise when absorbing training resources. When studying multi-function display cockpits, it is necessary to use interactive training devices in which displays must operate under power and possess the required capabilities. Training on hardware is impracticable in some cases, and unadvisable in others. The use of the integrated simulator for training in various disciplines is limited as the simulator is primarily designed to impart primary aircraft control skills rather than for classroom training. The article deals with the issue of upgrading pilot-trainees training skills during the familiarization with the cockpit equipment using an interactive DA-42T aircraft cockpit mockup with all the controls and indications (except for the control stick and pedals), including two primary multi-function displays and one backup, during the process-oriented training of the university. The operation of multi-function indicators is implemented in the form of special devices with a display and a push-button frame connected to a specially developed program on a PC that simulates the aircraft data system operation. For this purpose, to be based on information from the Aircraft Flight Manual, the information frames, shown on multi-function displays in the DA-42T aircraft, are reproduced. The content of the developed frames duplicates completely the DA-42T aircraft indication, contributing to improving academic study and acquiring practical skills to work on the integrated simulator as well as in a real aircraft. The physical cockpit mockup controls also correspond, in terms of the appearance and location, to the controls in the real DA-42T aircraft cockpit. The procedure to develop simulators of multi-function displays and the DA-42T aircraft cockpit mockup is described. The capabilities to use simulators of multi-function displays and the DA-42T cockpit mockup in the process-oriented training to upgrade skills are described. The conducted research results are described; the advantages of using the interactive cockpit mockup in the process-oriented training are presented.

The article developed a gating technique that allows us to validate ADS-B data without the necessity to verify using the secondary surveillance radar or multilateration. Probabilistic models of the ADS-B data gating technique, as well as the algorithm for applying these models were proposed. Benchmark cases that occur when aircraft (A/C) positioning by ADS-B systems, determined by threshold values of navigation and pilot’s errors, were analyzed. The first benchmark case assumes not exceeding of navigation and pilot’s errors the bounds of the tolerance limits, which allows us to draw up a conclusion concerning the ADS-B data validation. The second one assumes exceeding of a pilot’s error the bounds of the tolerance limits under an allowable navigational error. Herewith, the air traffic controller (ATC) obtains a message about the proper ADS-B operation and the necessity to issue instructions to the pilot to correct a flight. The third benchmark case assumes exceeding of a navigation error the bounds of the tolerance limits under an allowable or not allowable pilot’s error. In this case, the ATC obtains a message about not valid ADS-B data and the incapability to use these systems. The simulation of the given benchmark cases was performed. In addition, the Rayleigh and Rice distributions were applied to implement the ADS-B data gating technique. The simulation results allow us to assess the required amount of accumulated ADS-B data for the evaluation. Thus, it was found that during the estimate based on the Rayleigh distribution, it is sufficient to accumulate 15–20 measurements, which, when transmitting 2 messages per second and under the condition of the normal ADS-B equipment operation, will take 8–10 s. During the estimate, using the Rice distribution, an accumulation of 25–30 measurements is sufficient, which will take 13–20 s. The developed method will allow the use of ADS-B systems at regional aerodromes with the low intensity of air traffic as the primary or sole surveillance means. 

The issues of ensuring the reliability of the finite element models (FEM) of the fuselage in the hatch cutout zone are considered at the early aircraft design stages. The purpose and tasks of research are formulated. To assess the reliability of mathematical models, the objects with standards were selected. The methods of experimental research and measuring instruments are discussed. The results of a comparative analysis of the numerical experiment with analytical solutions and full-size experiments data are presented. For the validation of FEM structures, the checkable characteristics and types of their verification are determined. The results of this research contain a discussion of the impact of finite element mesh details on a stress concentration factor, an adequacy of modeling the stress and strain field in the vicinity of the cutout and taking into account a nonlinearity in strength calculations of structures with stress concentration. This paper focuses on the analysis of modeling a framed cylindrical shell with a large rectangular cutout, for which full-size tests were conducted by TSAGI researchers. Strains of strong frames, limiting the cutout in a cylindrical shell, shearing and equivalent stress in the skin, normal stresses in stringers at the intersection with the strong frame, displacements of strong frames cross-sections at test points are analyzed. Based on the results of this research, the recommendations for modeling thin-walled fuselage structures in the vicinity of a large cutout, ensuring the performance of calculations with engineering accuracy were formulated.    

The article substantiates the relevance to develop an analytical-simulation model of fighter flight dynamics with a limiter for the permissible flight envelope during the split-S maneuver. The structure of the analytical and simulation model of a fighter, consisting of a combination of a flight test bench, a model of fighter flight dynamics, a model of an astatic limiter for the permissible flight envelope and a model of pilot control actions based on the theory of fuzzy sets, is presented. The structure of the model of fighter flight dynamics with a limiter for the permissible flight envelope, consisting of a system of differential and algebraic equations, a model of an integrated control system, a geometry, mass and balance unit, a unit for calculating aerodynamic forces, a power plant unit, a bank of aerodynamic performance, a unit for calculating feedback on efforts from flight controls, is presented. The model differs from the known ones by the availability of the split-S simulation unit, which is designed for the split-S simulation and the multi-iteration split-S simulation with different initial conditions to determine the basic split-S parameters, the kinematic flight operation performance and to construct the split-S implementation area. The split-S simulation unit comprises the specified value functions, a pilot control actions model, a unit for processing simulation results, a unit for determining the basic split-S parameters, and a database of operating modes. The specified value functions determine the specified values of the kinematic aircraft movement parameters, which are used to implement control in various phase coordinates of the maneuver. The model makes it possible to obtain reliable values of the kinematic fighter movement parameters under the semi-natural simulation with the participation of the pilot and the simulation split-S maneuver modeling using the pilot control actions model. 

The present paper presents a simulation model description developed for the aircraft performance estimation of the most popular electric vertical takeoff and landing aircraft (eVTOL) aerodynamic configurations with the electric (hybrid) power plant for the urban air mobility purposes. It focuses on the quadcopter-type eVTOL aircraft aerodynamic configurations using the unshrouded-propellers or ducted fans driven by electric motors. The aircraft performance analysis for aerodynamic configurations of the quadcopter and tilt rotor-quadcopters with the tilt rotors and wing with the all-electric (EP) or hybrid power plant (HP) is given. To compare aircraft performance, the estimation results for a conventional single-rotor helicopter with EP or HP are given. Based on the numerical solution equation of the aircraft existence, feasible structural components mass distributions for various types of eVTOL configurations were obtained. eVTOL aircraft performance, including the estimation of apparent and drag power for the airspeed range, from hovering to the maximum airspeed, as well as for the transition modes (tilt rotor aircraft and quadcopters) were estimated. The eVTOL aircraft flight range and duration with EP and HP at the straight and level flight mode were calculated. Specific mass characteristics of EP and HP components (batteries, generators, electric motors, etc.) to ensure acceptable eVTOL aircraft performance were identified. A comparative evaluation of considered eVTOL configurations for the purpose of their efficiency was performed. Aerodynamic calculations were carried out based on the known analytical techniques of the lifting propeller momentum theory with the data correction capability according to test results. The simulation model, obtained in this paper, can be considered in the phase of the preliminary choice as the first approach of structural parameters and aerodynamic configurations of prospective electric (hybrid) eVTOLs designed for the use as an urban air taxi.