Optimization of standard arrival procedures at Sheremetyevo airport using rnav path terminators

Holding patterns are established at international airports to make the arriving traffic flow smooth and efficient. One of the main aims of holding patterns is to extend the aircraft arrival route, which allows ATC units to arrange the sequence on the arrival routes more effectively. The article considers the current methods and offers new ideas to improve the efficiency of the inbound traffic flow management using Paths and Terminators concept with HA holding patterns for standard arrival routes at Sheremetyevo Airport. As the main idea for optimizing air traffic management on this stage and reducing the workload on the controller, it is proposed to create extra routes in addition to the existing ones which include holding patterns, that will be used when needed to ensure a well-ordered traffic. The probabilistic method is used to calculate the maximum capacity of existing and proposed arrival routes with holding patterns. The proposed options for restructuring the airspace of the Moscow Terminal Control Area with preserving waypoints of starting standard arrival routes are presented.

Аtmospheric wind flow around the mountain landscape in the vicinity of Danang airport and flight safety issues

Wind boundary layer flow over the mountain landscape and large structures located around runways (RWs) creates coherent vortex structures (CVSs) that can cross a glideslope and airspace in the vicinity of an airport. The aircraft, encountering a vortex structure, experiences significant changes of the aerodynamic forces and moments, what is especially hazardous due to proximity to terrain. From a mathematical point of view, the solution of this problem presents a challenge due to extremely large space – time scale of the phenomenon, the lack of relevant atmospheric models, as well as comprehensive initial – boundary conditions in numerical modeling. In this paper, a composite solution is constructed: the CVSs area generation is computed in sufficient details within the framework of the grid method. Based on the data obtained in the approximation of analytical functions, an initial vortex structure is formed, the evolution and stochastics of which are modeled within the potential approximation by means of Rankine vortices. The evaluation of the forces and moments increment from the impact of vortex structures on the aircraft was carried out by the panel method using the engineering approach. As an example, the CVSs, resulting from wind flow around the mountainous area of the Son Tra Peninsula, that is located short of RWs 35R-17L and 35L-17R of Da Nang airport, are investigated. To improve the computational grids quality and verify the method of solving the boundary value problem for the Reynolds-averaged Navier-Stokes equations, we used the criteria based on the principle of maximum pressure, requiring Q-parameter positivity property in the vortices cores and flow separation regions. A CVS related aviation event, involving a passenger aircraft MC-21, is studied. The aircraft, after takeoff from RW 35R-17L setting the course close to the direction of the vortex wind structure axis from the Son Tra Peninsula, encountered the mountainous area CVS.

Effect of paragliding wing dome shape on its aerodynamic characteristics

Double-membrane gliding parachutes (DGP) obtain their wide variety of application, including the solution of cargo transportation problems. This parachute is a flexible canopy, which shape is maintained by ram air. In terms of the aerodynamic performance calculation and analysis when operating, DGP is the most complex aero elastic system. The computation of DPG aerodynamic performance is only possible, utilizing the methods of nonlinear aerodynamics and the nonlinear theory of elasticity methods.This paper investigates the aerodynamic characteristics of stable geometric shapes for various gliding parachutes, taking into account their dome shape both chord-wise and span-wise. Notably, the volumetric parachute profile is modeled by its median surface. The research, conducted by the authors, showed that such an aero elastic model of DGP allows you to obtain results that reflect correctly the qualitative effects of detached and free streamline flow. To solve the problem about the airflow over a gliding parachute, considering its canopy curvature, the method of discrete vortices with closed frames is employed, which allows you to calculate the paragliding wing aerodynamic performance within a wide range of angles of attack. There is also a possibility of flow separation simulation. The ideal incompressible liquid flow over the median surface of a stable shape for a double-membrane gliding parachute is regarded. The parachute fabric porosity is not analyzed, since the upper and lower DGP panels are made of either the low permeable or non-porous fabric. In the separated flow past, the aerodynamic coefficients are identified by time averaging to its large values after computing. The DGP aerodynamic performance computation results are given at a different value of its dome shape, as in the free streamline flow as in the flow separation. The computed coefficients, that allow us to consider the influence of canopy dome shape on its aerodynamic characteristics, are obtained. The proposed technique can be used for operational estimates of aerodynamic forces while designing and planning a pipe experiment.

Fatigue life predictions of carbon fiber reinforced plastic in specimens of double-shear bolted joint

It is noted that in modern aircraft composite structures there is a significant number of composite and metal-composite shear bolted joints, the fatigue life of which is an important factor to ensure the operating safety of such constructions. Thus, special attention is given to the evaluation of the layered composites fatigue life in such joints during tests and calculations of the similar structures components. Despite a considerable number of publications and studies on this subject, it can be observed that many important methodological issues have not been solved yet in this field. These problems can deal with the choice of the main mode of layered composites fatigue damage in shear bolted joints; the uncertainty of the basic fatigue curve; the practical absence of some models, representing diagrams of constant life fatigue for the layered composites in the joints under consideration; the uncertainty of fatigue damage summation rule in the layered composites in the investigated joints. Based on the review results and the data analysis of domestic and foreign publications including the results of specially conducted studies, the solutions to these problems are proposed. The proposed solutions were verified by analyzing the calculated and experimental data on the fatigue life of carbon fiber reinforced plastic laminates НТА7/6376 [45/-45/0/90]3S in the double-shear bolted joints specimens.

The use of the X-Plane flight simulator and SimInTech environment in the educational process during the practical lesson "Flight data processing"

During training sessions at an aviation university, it is advisable to demonstrate samples of aviation equipment, individual elements of systems and assemblies, or use specialized stands and posters. However, when conducting classes remotely, not all of these materials can be used, since it is not always possible to show them in dynamics and thus ensure the formation of a clear idea of students about the object being studied. The article considers an example of using a flight simulator in the educational process as a means of visualizing aviation equipment during a practical lesson "Flight data processing". Visual perception of the materials of objective control does not give a complete understanding of the dynamics of the aircraft flight, its attitude while executing pilotage and aerobatics elements, therefore, it is necessary to demonstrate the performance of flight elements with the simultaneous display of flight parameters in a graphical form. For this purpose, the X-Plane flight simulator is used, for interaction with which a project has been developed in the SimInTech environment that implements data exchange for flight control of an aircraft model and registration of parametric information for its further analysis. Schemes for simulating the operation of on-board recording devices are described. The ways of solving the tasks are described. The possibility of using the developed projects for remote training of aviation specialists, as well as the implementation of the results obtained in the educational process of aviation universities, is indicated.

The jet fuels anti-wear properties indicator

There are three main fuel brands for jet engines of civil aviation used: domestic TS-1 and RT and foreign, produced in relatively small volumes in Russia, JET A-1 (JET A-1). Since the end of the 2000s, foreign manufacturers have made claims to the quality of the mass-used domestic fuel brand TS-1, and these claims have not been specified. However, the service life of a number of foreign engines operating on TS-1 fuel has been reduced by 50%. This circumstance can be caused by both subjective reasons – commercial and political interests of equipment manufacturers, and the objective ones. The main objective reason may be that recently several Russian plants producing TS-1 fuel have begun to produce composite propellant under the same name, where products of secondary oil refining processes are added to the straight-run fractions. These fuels meet the requirements of the standard (GOST 10227-86), which does not contain an indicator that characterizes the anti-wear properties of jet fuels. In the standard for JET A-1 fuel, anti-wear properties are normalized, and they are also normalized in the standard for domestic fuels for supersonic aviation. The article presents comparative tests of anti-wear properties of samples of jet fuels used in the civil aviation. The article substantiates the relevance of the anti-wear properties indicator in the standard for domestic brands of jet fuels for subsonic aircraft introduction, as well as the comparative analysis of the anti-wear properties of fuels produced by various Russian oil refineries. Indicators and methods for assessing the anti-wear properties of aviation fuels can be different. As such an indicator, it is proposed to use the anti-wear properties indicator calculated after testing fuel samples on a four-ball friction machine.

Computational studies of the rotors aerodynamic characteristics of multirotor drones

The article presents the results of computational studies of aerodynamic characteristics for unmanned lift-generating multi-rotor drones of various configurations. The distinctive features of rotors flow were characterized. The rotor interaction was evaluated. The computations were based on the nonlinear rotor blade vortex theory in a non-stationary arrangement. The combinations of four, eight (four coaxial) and fourteen two-bladed rotors at velocity V = 100, 150, 200 km/h were considered. Semi-empirical methods were employed to select the rotor angles of attack, rotation speed, blade installation angles and geometric parameters at the given take-off weight for each combination of rotors and flight airspeed. The computations showed that for a four-rotor lift-generating design (quad-rotor), two rotors installed downstream, depending on the velocity due to the mutual effect, have values of the thrust coefficients ≈10...20% less than those of the rotors located upstream. For a coaxial quad-copter, the effect of the upper front rotor on the upper rear rotor is similar to the effect of the front rotors on the rear ones in a four-rotor lift-generating design. The effect of the upper front rotor on the lower rear rotor does not vary in terms of the average thrust value, and variations are only local in nature. The interaction of other rotors is identical to that of the four-rotor version. A fourteen-rotor lift-generating multi-rotor drone has a complex flow pattern, which generates deviance in the thrust coefficients variation with respect to time. Depending on the mode and rotors location, the average rotor thrust coefficient can vary approximately twice. The computations showed that with the similar geometric parameters and kinematics characteristics, rotors thrust is substantially subject to variation, which causes destabilizing moments to a significant degree without additional control input. Thrust pulsations and, respectively, vibrations grow in intensity as the flight airspeed increases. Probably, the right choice of the rotor configuration and the automatic control system can counterbalance thrust surge by so-called "phasing", i.e. selecting an initial azimuth angle for each rotor.

Analysis of the propellers-airframe interaction of the light transport aircraft

In the design of multi-engine aircraft, one of the important issues is the interaction between the propellers and airframe configuration components, especially in take-off and go-around procedure modes. Modern propeller-driven aircraft concepts in the pulling configuration are characterized by a high disk loading and an increased number of propeller blades used to increase cruising speed and reduce excessive noise. The first problem arising due to high disk loading is the direct impact of forces by operating propellers (thrust, normal force) on fixed-wing stability, especially at angles of attack different from a zero value. The second one involves a high-energy level of the propeller slipstream, having a significant indirect impact on the aircraft’s aerodynamics, stability and controllability. This impact is primarily associated with the interaction of propellers slipstream with other aircraft’s configuration elements. The complexity of taking into account the slipstream-wing interaction and other airframe components stipulated the application of experimental methods to study the problems of propellers – airframe interaction while designing propeller-driven aircraft configurations. This article presents an analysis of the experimental studies results of the operating propellers- airframe interaction for a light twin-engine transport aircraft. The aerodynamic aircraft’s configuration is executed using the conventional pattern of a high-wing and the carrier-on deck type empennage. The high-lift wing device is a fixed-vane doubleslotted flap. The wind-tunnel tests of the model in the cruising, takeoff and landing configurations were carried out in TsAGI lowspeed wind-tunnel T-102. Measurement of forces and moments, acting on the model, was performed by means of an external sixcomponent wind-tunnel balance. Measurement of forces and moments, acting on the propeller, was conducted using strain gauge weighers installed inside the engine nacelles of power plant simulators. The simultaneous combined use of external and internal balances allowed researchers to determine the direct and indirect contribution of operating propellers to the model longitudinal aerodynamic characteristics under variation of loading factor B ranging from 0 to 2.

Application of the multidimensional statistical analysis in the development of an integrated safety management system in an aircraft maintenance organization

Modern aviation enterprises are lots of risks-related owners associated with execution of their activities. Nowadays there are various management systems such as a Quality Management System (QMS), Safety Management System (SMS), etc., which describe all the potential risks for an organization. The problem of synchronization and unification of these systems in the framework of a comprehensive analysis of managing changes and fulfilling production operation remains unsolved at this point. To settle this problem, the article suggests using an integrated safety management system (ISMS). When developing ISMS in an aircraft maintenance organization that integrates the management systems of flight safety, quality, aviation, information, environmental safety, etc., the organization encounters the problem of data redundancy and duplication about manifestations of hazard factors in various aspects of its activities. This can make it difficult to collect and process data and take corrective/preventive measures. The issue of reasonable reduction of the original list of hazard factors can be considered as the subject of decreasing the dimension of the entity activity model, which can be solved using the method of the factor analysis principal components. Furthermore, application of the principal components method provides an expert analyst with supplementary, scientifically-based data on the quality of work and allows him to predict trends. The article based on real data of the aircraft maintenance organization shows the applicability of the method with the purpose for optimizing the list of hazard factors manifestations regarding a single aspect of organization activity.

Scientific basis for the trainer aircraft anti-g equipment requirements

The design process of a new aircraft (AC) is always associated with the issue of choosing its basic technical parameters, or, in other words, the formation of its conceptual design. In case of a civil aircraft, the choice of these parameters is defined by the requirements for operational safety, market conditions, norms that specify the tolerable harmful impact of the aircraft on the environment, etc. In case of a military aircraft, its outlay mostly depends on the concept of potential military threats, ways of using the military aircraft in military conflicts. Some of these requirements are formulated in regulatory documents – the Aviation Requirements for Civil Aircraft and the General Tactical and Technical Requirements of the Air Force for Military Aircraft. For example, Part 25 of the Aviation Requirements for Civil Aircraft defines the Airworthiness Standards for transport aircraft. It should be noted that the stated above requirements are often a tool of competition, for example, when tightening the aircraft noise abatement procedures provides advantages for particular manufacturers, not admitting other manufacturers to enter the market, whose aircraft do not conform to the new standards. Thus, complying with the requirements virtually involves additional costs both in the aircraft development and during its operation. In addition, the implementation of the requirements stated above can lead to the deterioration of the aircraft’s performance, and hence, to the decrease of its competiveness and combat effectiveness. Therefore, each requirement of the regulatory documents should have a profound scientific rationale. This article analyzes one of the regulatory documents requirements referring to the necessity of anti-g system on board aircraft. The authors propose the approach to specify the existing criterion to provide the scientific basis for the anti-g system on board aircraft by assessing the actual level of pilot load when maneuvering. The subject under study is of particular importance for the Yak-152 trainer aircraft. The actual level of loads during pilotage of the Yak-152 trainer aircraft does not require the use of the anti-g system but if to be based on a formal criterion, namely, in terms of the maximum operational overload value, the aircraft should be fitted out with such a system.