Managing the interaction of liquids with surfaces is of great interest over a wide range of practical applications: the possibility of aircraft complete ice protection, a reduction of the friction coefficient by tens of percent, an increase in fluid flow in pipes and channels; however, the models of a number of the above processes are far from completion. This paper describes the flow modes of liquid around a hydrophobic body containing air in its pores in application to problems of aircraft icing and reducing liquid friction when it flows around solid bodies. Analytical expressions for liquid flow in channels, where lubrication on the walls allows for sliding, have been obtained, as well as estimates of parameters for washing away of the air lubrication layer from the pores of the hydrophobic coating. Using examples of flow between plates and in a cylindrical pipe, the influence of the lubrication layer thickness on fluid flow is shown, specifically demonstrating the potential increase in flow by several tens of percent due to sliding. A physical-mathematical model has been developed for calculating the elementary interaction act of a flow molecule with a solid body to reduce the time of molecular simulation while taking into account important physical features. New original analytical expressions for the rebound coefficients of molecules from the surface of a solid body have been obtained, depending on its physical properties and temperature. Interaction models have been developed using the example of water molecule and solid aluminum body, with values of the velocity change coefficients for molecular during collision obtained. Based on an analysis of known experimental data, the dependence of the contact angle of water droplets on a flat surface on the Debye temperature of the material has been demonstrated. The results obtained and the developed mathematical models can be used to create coatings that prevent or completely eliminate aircraft icing, particularly the formation of barrier ice during the flow of solidifying liquid film and droplets on the surfaces of streamlined elements of the aircraft.

The scientific article is the result of a study aimed at creating a mathematical model for diagnosing defects in aircraft structural elements made of composite materials. Its feature is an innovative approach to assessing the probability of defects and their characteristics, based on the analysis of the material properties and technical parameters of the structure. The developed model combines methods of statistics, mathematical modeling and data analysis, which provides more accurate and reliable results. The findings obtained from the study may be of great value in improving diagnostic and quality control methods in aircraft manufacturing and operation. This in turn helps to improve the safety and reliability of aircraft, which is one of the main priorities of the aviation industry. The use of mathematical modeling can significantly increase the efficiency of diagnostics and quality control, which in turn has a positive effect on the technical operation of aircraft as a whole. Comprehensive analysis of defects in aircraft composite structures is effective in improving detection accuracy and optimizing maintenance. In modern aviation, where safety and reliability are crucial, the use of mathematical modeling provides the opportunity not only to identify defects, but also to predict their further development, providing preventative measures. This approach also improves aircraft productivity by reducing maintenance and repair time, which can ultimately increase airline revenues. Standardization of diagnostic processes and the introduction of new technologies in the field of defect detection represent important directions for future research. However, it is also necessary to consider the cost-effectiveness and practical applicability of the developed models and methods.

The article is devoted to the issue of evaluating the piloting performance of an aircraft, taking into account various factors that have a special effect on the control process. The article presents the results of work on the creation of models of a digital indicator on the windshield and the power circuit of the hydraulic system and consumers in the longitudinal control channel of the aircraft for conducting research in the field of assessing their impact on piloting accuracy when the aircraft moves along an assigned flight path during landing. The features of the process of developing the elements of the indicator on the windshield, namely the indicators of the director ring and the velocity vector, their control law when the aircraft moves along an assigned flight path are presented.  The implementation of the effect of the hinge moment on the steering actuators in the model of the hydraulic system of the aircraft when the stabilizer consoles deviate from a neutral angular position is described. The principle of integration of a Simulink model of a hydraulic system and a flash model of a windshield indicator with a model of spatial motion of a heavy aircraft is presented. The results of semi-natural simulation on a flight simulator are presented, on the basis of which the values of deviations from a given flight path are calculated when performing a turn in a circle, the mode in which the hinge moment limits the angle of deviation of the stabilizer consoles is determined. It is concluded that it is advisable to create and use an experimental base to provide research in the field of assessing the impact of promising information sources that provide flight information to the crew in poor weather conditions, and the operation of the hydraulic system on the aircraft piloting performance and the pilot’s control actions in various flight modes of the aircraft.

The increased efficiency of turboprop engines in cruising flight as well as low operating costs have determined the economic feasibility of using regional propeller-driven aircraft to transport 40–80 passengers on short routes within one country or connecting two nearby regions (for example, in Russia). The aerodynamic performance requirements for regional aircraft, determined from typical flight missions for the Russian and European markets differ greatly in range and required runway lengths. The typical flight range in Europe is about 800 km, while in Russia it increases to 1500 km due to the limited number of airports and aerodromes in operation. The limitation on runway length is 1300 m (airfield class G) for aircraft with a maximum take-off weight and 1000 m (class D) with a payload of up to 70% of the maximum value. The ability to take off and land from unpaved runways is also an essential requirement in Russia. This leads to a more complex design and an increase in the weight of the airframe, as well as to the need to increase the wing lift. Most of the operating European regional aircraft previously did not have tight restrictions on runway lengths and their takeoff and landing characteristics were not active constraints when forming wing configurations. However, the recently observed growing demand for air travel leads to a significant increase in the load on hub airports and, as a result, to the delay of many flights. One of the possible ways to solve this problem is to relieve the major hub airports by transferring regional aircraft service to nearby local airports. This will require both the modernization of existing airports and the development of a new generation of aircraft with short takeoff and landing distances (STOL). The development of STOL aircraft which are capable of connecting local airports and small towns has been conducted for many years. The STOL performance can be achieved by both developing an effective high-lift system with increased lift effectiveness and wing load alleviation. Wing load alleviation, often used in the light aircraft transitional category, leads to deterioration of cruising performance and increased sensitivity to atmospheric turbulence, especially at low altitudes. This makes difficult to track the final approach paths when controlling the pitch angle by deflecting the elevator. Therefore, a more preferable and more often considered option to reduce takeoff and landing distances of commercial airplanes is the increase of lift performance in combination with a set of additional technical solutions. Significant advances in the application of computational techniques for the development of swept wing high lift devices for long-haul aircraft with high lifting properties (Cy_max ≈ 3), including a retractable Fowler flap and a three-position slat, make it possible to use a similar approach to the design of high-lift system for new regional aircraft. Taking into account the specifics of aircraft operation at local aerodromes, a complex of technical solutions has been considered to increase wing lift at low flight speeds, as well as additional measures to reduce the landing distance. The results of computational and experimental studies of the proposed technical solutions are presented with an assessment of the effectiveness of their use on a regional aircraft of the ATR 42-600 type.

This study describes the main structure and algorithm development principles of flight control systems for tiltrotor aircraft using the example of rotary-wing aircraft V-22 Osprey and AW609. A brief overview of convertiplane performance is provided. Typical conversion corridors are given using the example of convertiplanes XV-15 and AW609. The principles of V-22 and AW609 tiltrotor control system development are described. The design objectives of the automatic control system of the convertible aircraft are listed. The structure of the control system is discussed in detail. The development principles of control laws for Normal and Direct operational modes are described. Hydraulic power supply systems for control actuators are considered. Examples of the main control system architecture with triple redundancy for V-22 and AW609 convertiplanes are given. Main characteristics of tiltrotor control laws are given. Main functions of tiltrotor automatic control systems are described. Methods for ensuring high reliability of the flight control system, ways to reduce crew workload in order to ensure compliance with the regulatory requirements of V-22 tiltrotor handling qualities are considered. Features of AW609 tiltrotor flight control system development, requirements for control laws which make it possible to reduce crew workload, improve handling qualities and increase the reliability of the control system are considered. As an example, the automatic flight control system (autopilot) algorithm synthesis of a light tiltrotor for all flight modes (helicopter, aircraft and conversion) is given. The possibility of using a relatively simple algorithms and structure of automatic control system during the flight and conversion between the helicopter – aircraft – helicopter modes is shown.

Due to the effective use of the results of scientific and technological progress, the Armed Forces of the Russian Federation are constantly equipped with new weapon systems, which fully applies to aviation. The Aerospace Forces receive modern combat (attack) helicopters, the effectiveness of which is largely determined by its performance and operational characteristics. The specificity of strike missions, the possibility of operation from sites, the need to operate at extremely low altitudes and in conditions of strong countermeasures of enemy air defense in a rapidly changing environment impose unique requirements to the performance of modern combat helicopters. The corresponding performance of attack helicopters are provided by the features of their design and layout. The existence equation allows to relate the performance of a helicopter with its technical parameters and take-off weight. The paper offers a method for approximate determination of the normal take-off weight of a modern combat helicopter based on the existence equation. This method is based on expressions showing the dependence of the relative masses of helicopter parts with its performance and technical parameters. These expressions are obtained on the basis of generalization of the material of existing sources and their updating to the weight calculation of aircraft with performance and technical parameters of corresponding modern combat helicopters. On the basis of the offered approach, a program for a personal computer was developed, through which the normal take-off weight was determined and the weight analysis of the parts of the helicopter in service was carried out. The obtained results are in satisfactory agreement with the prototype data. The developed methodology and program can be used in research to substantiate the tactical, technical and operational requirements for modern combat helicopters, as well as in choosing areas of modernization and analyzing the interdependence of tactical, operational and technical properties of combat (transport and combat) helicopters in service.