Airborne Aircraft Research Articles

Interference Study of 5G System on Civil Aircraft Airborne Beidou RDSS System in Takeoff and Landing Phase

Interference Study of 5G System on Civil Aircraft Airborne Beidou RDSS System in Takeoff and Landing Phase

Characteristics of operational control reliability of aircraft functional systems and avionics suites

The operational control system (OCS) of civil aircraft (A/C) airborne equipment is an important component of its technical operation system (TOS). Operational control is an integral part of the technical operation process. It makes it possible to assess the technical conditions (TC) of the objects to be monitored in various states of airborne equipment operation, aircraft preparation for flight, various types of maintenance and recovery. The main property of operational control is the reliability of control. The key task of operational control is not only to determine the type of technical condition, but also to quantify the correctness or erroneousness of decision-making. Control reliability characteristics (CRC) are quantitative indicators of the degree of objectivity in decision-making. Depending on the level of task details, it is necessary to distinguish the control reliability characteristics of units, functional systems (FS) and avionics suites for various means of operational control: built-in test equipment (BITE), on-board self-contained, ground-onboard and ground systems. The choice of the control reliability characteristics is based on the system analysis and the mathematical apparatus of logic, probability theory and mathematical statistics. Rational sets of technical states and decision-making about the technical conditions of functional systems and avionics suites are formed. Based on these sets, three groups of control reliability characteristics were identified. The first group consists of conditional probabilities of transitions in the operational control process under various types of control. The second group consists of unconditional probabilities of transitions in the operational control process under various types of control. The third group consists of a posteriori decision-making probability in the operational control process under various types of control. Analytical dependences for calculating the control reliability characteristics of three groups for functional systems and avionics suites and relationships between them are determined. The air-conditioning system was used to calculate the reliability of the control.

Bracket design and natural frequency analysis of civil aircraft inertial reference unit

The Inertial Reference Unit (IRU) is an important and indispensable airborne equipment for civil aircraft, which is used to provide information on aircraft attitude, heading, acceleration and so on. The design of its bracket will directly affect the signal accuracy of the equipment. In order to ensure the accuracy of the information of the measuring equipment, the stiffness design of the support has strict requirements to avoid the impact of vibration and elastic deformation on the accuracy of the output signal. Through theoretical formula derivation and finite element analysis, this paper summarizes the influence of different bracket structure forms on the natural frequency and obtains the scheme to improve the natural frequency of the bracket. By increasing the flange height, adjusting the lightening hole on the plane mounting plate of the bracket and making the plane mounting plate, frame and skin form a box-shaped structure, the torsional stiffness of the bracket is enhanced. The results show that the improved bracket meets the requirements of natural frequency which is greater than 110 Hz, which can provide a reference for the design and strength analysis of similar aircraft airborne equipment.

A Study on the Normalized Delineation of Airspace Sectors Based on Flight Conflict Dynamics

The study of airspace sector demarcation can help controllers to deal with complex air situations, provide reference for air traffic control services, reduce the workload of controllers, and ensure safe and efficient airspace operation. Based on complex network theory, this paper proposes a sector division method based on a mean shift clustering algorithm and a Voronoi diagram. Firstly, a flight conflict network is constructed based on the structural characteristics of the airborne flight situation, combined with the three-dimensional velocity barrier method and the aircraft protected area model. Secondly, six network topology indexes, such as the total node degree, average point strength and network density, are selected to construct the flight-situation-assessment index system, and the busy and idle time segments of the airspace are divided according to the comprehensive network indexes; finally, based on the historical flight data, the airborne aircraft in the busy and idle time segments are clustered using the mean shift clustering algorithm and the Voronoi diagram method, respectively, so as to obtain a sector division scheme. The simulation results show that this method can equalize the network topology indexes and provide a reference for the scientific allocation of controllers’ energy.

A two-stage energy management for integrated thermal/energy optimization of aircraft airborne system based on Stackelberg game

As a new integrated airborne electromechanical system, APTMS extracts air, shaft power and fuel from aircraft engines which will cause complex effects on fuel consumption and stability margin of aircraft engine. The performance conflict between aircraft engine and APTMS caused by multiple forms of energy cross-linking greatly increases the difficulty of energy management and optimization. Considering the contradictory of the optimization objectives of this coupling model. a two-stage Stackelberg game is proposed to solve the energy optimization. By setting aircraft engine as a leader and APTMS as a follower with the constraints, an energy optimization Stackelberg game is established. The existence of Stackelberg equilibrium is proved by multivariate nonlinear fitting and the value of equilibrium is obtained by dynamic iteration. Additionally, in order to jump out of the local optimal solution, adaptive chaos search particle swarm optimization (ACPSO) is introduced to the solution accuracy. Finally, compared with multi-objective optimizations base on Pareto equilibrium under typical conditions, the advantages of this new method are verified.

Analysis of Abnormal Flight and Controllers Data Based on DBSCAN Method

In order to quickly and timely analyze the airborne and controllers data of domestic ARJ21 (Advanced Regional Jet for 21st Century) aircraft and find out the existing flight problems and potential safety hazards, this paper proposes a DBSCAN (density-based spatial clustering of applications with noise) clustering analysis method for aircraft airborne and controllers data outlier detection to evaluate and monitor the flight status. The flight QAR (quick access recorder) data stored in the aircraft rapid data recorder are input to the DBSCAN clustering analysis algorithm to detect the flight parameters that are different from the normal range. Compared with the traditional airborne data analysis method, this method can realize the real-time analysis and prediction of data, improve the efficiency of data analysis, and find the potential security risks according to the analysis results and deal with them in time. In this paper, 1,102 ARJ21 aircraft operation data are used to test. The results show that the DBSCAN clustering anomaly data detection method based on density is fast and accurate in detecting the continuous parameters recorded in the flight process, and the display results are easy to analyze, which can predict the potential safety problems in time. The outliers detected by this method can provide support for the controller to detect the outliers and related flight risks in daily flights.

Research on the Built-in Test Design of Civil Aircraft Flight Control System

Abstract Based on ARINC 624 for civil aircraft airborne maintenance system, the working modes and application forms of civil aircraft Flight Control System Built-in Test (BIT) design are given. The test principles and implementation methods of the civil aircraft Flight Control System Power-on BIT and Initiated BIT are analyzed in detail, and the overall functional architecture of the civil aircraft Flight Control System BIT is described. Taking the actuator as an example, the realization method of its return to service test is analyzed. Finally, the general characteristics of the BIT technology of the civil aircraft Flight Control System are summarized.

A Two-Stage Energy Management for Integrated Thermal/Energy Optimization of Aircraft Airborne System Based on Stackelberg Game

A Two-Stage Energy Management for Integrated Thermal/Energy Optimization of Aircraft Airborne System Based on Stackelberg Game

Fuzzy Logic in Aircraft Onboard Systems Reliability Evaluation-A New Approach.

This paper is a continuation of research into the possibility of using fuzzy logic to assess the reliability of a selected airborne system. The research objectives include an analysis of statistical data, a reliability analysis in the classical approach, a reliability analysis in the fuzzy set theory approach, and a comparison of the obtained results. The system selected for the investigation was the aircraft gun system. In the first step, after analysing the statistical (operational) data, reliability was assessed using a classical probabilistic model in which, on the basis of the Weibull distribution fitted to the operational data, the basic reliability characteristics were determined, including the reliability function for the selected aircraft system. The second reliability analysis, in a fuzzy set theory approach, was conducted using a Mamdani Type Fuzzy Logic Controller developed in the Matlab software with the Fuzzy Logic Toolbox package. The controller was designed on the basis of expert knowledge obtained by a survey. Based on the input signals in the form of equipment operation time (number of flying hours), number of shots performed (shots), and the state of equipment corrosion (corrosion), the controller determines the reliability of air armament. The final step was to compare the results obtained from two methods: classical probabilistic model and fuzzy logic. The authors have proved that the reliability model using fuzzy logic can be used to assess the reliability of aircraft airborne systems.

Fatigue Life Analysis of Aluminum Alloy Notched Specimens under Non-Gaussian Excitation based on Fatigue Damage Spectrum

In this study, a non-Gaussian excitation acceleration method is proposed, using aluminum alloy notched specimens as a research object and measured acceleration signal of a certain airborne bracket, during aircraft flight as input excitations, based on the fatigue damage spectrum (FDS) theory. The kurtosis and skewness of the input signal are calculated and the non-Gaussian characteristics and amplitude distribution are evaluated. Five task segments obey a non-Gaussian distribution, while one task segment obeys a Gaussian distribution. The fatigue damage spectrum calculation method of non-Gaussian excitation is derived. The appropriate FDS calculation method is selected for each task segment and the acceleration parameters are set to construct the acceleration power spectral density, which is equivalent to the pseudo-acceleration damage. A finite-element model is established, the notch stress concentration factor of the specimen is calculated, the large mass point method is used to simulate the shaking table excitation, and a random vibration analysis is carried out to calculate the accelerated fatigue life. The simulation results show that the relative error between the original cumulative damage and test original fatigue life is 15.7%. The shaking table test results show that the relative error of fatigue life before and after acceleration is less than 16.95%, and the relative error of test and simulation is 24.27%. The failure time of the specimen is accelerated from approximately 12 h to 1 h, the acceleration ratio reaches 12, and the average acceleration ideal factor is 1.125, which verifies the effectiveness of the acceleration method. It provides a reference for the compilation of the load spectrum and vibration endurance acceleration test of other airborne aircraft equipment.

Operational control system of civil aicraft airborne equipment and scientific basis of its formation

The system of operational control (SOC) of civil aircraft (CA) airborne equipment incorporates onboard equipment, as an object of control, means and programs of operational control, maintenance personnel of an operating enterprise, carrying out procedures using control means and organizing processes of operational control for the specified objects using control programs. Quality of A/C onboard equipment SOC becomes obvious in the process of operational control. Operational control is a set of processes for determining the technical condition (TC) of objects of control (OC) at the various operational stages: in flight, during operational maintenance (pre-flight and post-flight control), and periodic maintenance, after dismantling equipment from board. The process of determining OC TC of includes control, diagnostics, forecasting and recovery. The process of operational control is characterized by reliability of control – the property of TC control, which determines the extent of display objectivity as a result of monitoring the actual OC TC. Based on the SOC analysis as an object of research, the analysis of the problem of its forming and updating as well as the developed hierarchy of criteria for the effectiveness of interacting systems, the general problem will be formulated as follows: on a given set of parameters of onboard equipment SOC, let us determine the parameter values so that the system costs in the process of operational control reach minimum while performing all the required tasks and observing all the limitations for own parameters of the system as well as indicators of its technical efficiency.

Structural dynamic response analysis due to the slit flow between the tailplane and the elevator

Any aircraft in flight is subjected to dynamic loads. Following vibration-related accidents, a flow field and vibration analysis can be carried out to analyze the data and study the cause of the accident. When slit airflow enters the cavity between the tailplane structure and the elevator, a mixed vortex is formed. If the vortex-induced vibrational frequency of around 50 Hz happens to be close to the natural frequency of the structure at 46 Hz, it is likely to induce structural vibration (resonance). The resonance can cause excessive fatigue damage which can ultimately lead to structural failure and the loss of the component or the aircraft. Damping methods can be employed to control vibration within the structure by reducing the amplitude of that vibrational motion by 83%. This article details a recreation of one example of structural vibration within an airborne aircraft.

The Design Assurance Method of Reused Airborne Software

Reusing software data from different sources and different reuse methods will affect the full compliance of civil aircraft airborne software. To achieve cost and risk reduction in reused software project, firstly classification of reused airborne software is confirmed and assessment elements are recognized; secondly the assessment framework of software reuse is established and assessment activities and sequences are specified; lastly the reused software design assurance requirements are given from the perspective of certification. This study can provide support for stakeholders of reused software certification to recognize and assess reused software and generate certification strategy in the early stage of project.

Research on the Highly Accelerated Stress Screening (HASS) Test Process of Civil Aircraft Airborne Equipment

The reliability of the airborne equipment of civil aircraft is highly concerned by the aircraft Original Equipment Manufacture (OEM), airlines, passengers and airworthiness authorities, and is the key to ensuring the safety and punctual operation of the aircraft. The Highly Accelerated Stress Screening (HASS) test is one of the effective test methods to ensure that the product reaches the expected reliability level, and it has been widely used in aviation, high-speed rail, automobiles and other fields. Based on the characteristics of civil aircraft airborne equipment, combined with the universal method of HASS test, this paper investigates the application process of HASS test on airborne equipment, and gives the method for determining the test object of airborne equipment by HASS, and the test of HASS, the principles of test profile design, follow-up verification and troubleshooting methods. The research can be applied to the HASS test work of civil aircraft airborne equipment, and guide the development of HASS test, so as to effectively propose defective products in the manufacturing stage and improve the reliability of the installed airborne equipment.

Compensation of Positioning Errors Caused by Tropospheric Wave Propagation in Wide-Area Multilateration Systems

Introduction. Wide area multilateration (WAM) systems are the main competitors of secondary surveillance radar (SSR) systems used in air traffic control (ATC). The general principle of WAM operation is based on the assessment of pseudoranges between a signal source (an aircraft airborne transponder) and the ground receivers with precisely known geographical coordinates deployed over the ATC area. The aircraft position is estimated by measuring pseudoranges. A significant factor affecting the accuracy of aircraft positioning is tropospheric refraction, a phenomenon caused by the inhomogeneity of the earth's atmosphere and manifested in a deviation in the direction of the rays along which the signal of an aircraft transponder propagates. Refraction increases the lengths of ray paths, thus increasing the corresponding pseudoranges. As a result, the estimate of the aircraft position receives an additional bias. Altitude estimates produce unreasonably large errors.Aim. To develop a mathematical model for the signals received by a WAM system, which accounts for tropospheric wave propagation, as well as to derive an algorithm for aircraft positioning with compensated tropospheric errors.Materials and methods. Equations for the pseudorange estimation errors caused by wave propagation in a spherically stratified atmosphere were derived using the method of geometrical optics.Results. This paper proposed a mathematical model for pseudorange estimates in WAM systems, which accounts for the bias associated with the phenomenon of tropospheric refraction. An analysis of the proposed model showed that pseudorange errors depend linearly on the distance between the aircraft transponder and the receiver. This conclusion allowed an algorithm for aircraft positioning with compensated tropospheric errors to be developed. The proposed algorithm yields an unbiased estimate of the aircraft position. The standard deviation of altitude estimates increases by 60%, although remaining within the limits permissible for WAM systems.Conclusions. The developed mathematical model of WAM signals, which considers tropospheric propagation errors in pseudorange estimation, as well as the algorithm for aircraft positioning with compensated tropospheric errors, can be used in the development of spatially distributed navigation systems.

Application of Multiphysical Domain Modeling in Electrical System Simulation

The energy structure change of more electric aircraft makes the aircraft airborne system more complicated. Each subsystem realizes the transmission, interaction, and conversion of energy and information through the dynamic coupling and coordinated control of electrical energy, mechanical energy, hydraulic energy, and thermal energy. This paper applies the multiphysical domain modeling method with the parameter identification according to the original model data. Based on the power conversion relationship of electrical equipment, it defines the port with the power potential variable and flow variable and is supplemented by the information control. It can show the dynamic characteristics, power conversion, and loss characteristics of the device itself. The models can conveniently perform the large-scale system integration, which not only can build the complex electrical equipment formed by multiphysical domain models with the series connection but also can build a complex power supply system formed by multiphysical domain models with the parallel connection.

Complex engineered system health indexes extraction using low frequency raw time-series data based on deep learning methods

Abstract Data analysis methods based on deep learning are attracting more and more attention in the field of health monitoring, fault diagnosis and failure prognostics of complex systems, such as aircraft airborne systems and engines. In this study, several health monitoring methods proposed from deep learning are demonstrated based on a real data set from an airborne system of commercial aircraft, where Health Indexes (HIs) are derived based on the raw sensor data to characterize the health state of the system in-service. Determining the optimal degradation evaluation index is the key to further failure prognostics. So, a set of metrics to characterize the suitability of different of HI deriving methods has been proposed. This metrics includes monotonicity, prognosability, and trendability. The better HI selected can effectively characterize the health state of aircraft air conditioning system, which is helpful for further failure prognostics and converting the scheduled maintenance into condition-based maintenance.

The Rapid Intensification and Eyewall Replacement Cycles of Hurricane Irma (2017)

Abstract The initiation of a rapid intensification (RI) event for a tropical cyclone (TC) at major hurricane intensity is a rare event in the North Atlantic basin. This study examined the environmental and vortex-scale processes related to such an RI event observed in Hurricane Irma (2017) using a combination of flight-level and airborne radar aircraft reconnaissance observations, microwave satellite observations, and model environmental analyses. The onset of RI was linked to an increase in sea surface temperatures and ocean heat content toward levels more commonly associated with North Atlantic RI episodes. Remarkably, Irma’s RI event comprised two rapidly evolving eyewall replacement cycle (ERC) episodes that each completed in less than 12 h. The two ERC events displayed different secondary eyewall formation (SEF) mechanisms and vortex evolutions. During the first SEF event, a secondary maximum in ascent and tangential wind was observed at the leading edge of a mesoscale descending inflow jet. During the ensuing ERC event, the primary eyewall weakened and ultimately collapsed, resulting in a brief period of weakening. The second SEF event displayed characteristics consistent with unbalanced boundary layer dynamics. Additionally, it is plausible that both SEF events were affected by the stagnation and axisymmeterization of outward-propagating vortex Rossby waves. During the second ERC event, the TC continued to rapidly intensify, which is a stark contrast to the ERC paradigm described in the literature. The differing ERC evolutions appear linked to the vortex response to changing environmental conditions. The results presented here underscore the utility of frequent aircraft reconnaissance observations for an improved understanding of TC dynamics.

КОНЦЕПЦІЯ СТВОРЕННЯ СИЛОВОЇ УСТАНОВКИ СІМЕЙСТВА РЕГІОНАЛЬНИХ ПАСАЖИРСЬКИХ ЛІТАКІВ АН-148/АН-158

The basic results of calculation and research works carried out in the process of creation of power unit of regional passenger airplanes’ family are given. The design features of the propulsion engines and engine of the auxiliary power plant are described. The aforementioned propulsion system includes propulsion engines D-436-148 and engine AI-450-MS of auxiliary power plant. In order to comply with the requirements of Section 4 of the ICAO standard (noise reduction of the aircraft in site), in part of ensuring the noise reduction of engines, when creating the power plant of the An-148/An-158 aircraft family, a single- and double-layer acoustic filler was used in the structure of the engine nacelle and air intake. The use of electronic system for automatic control of propulsion engines such as FADEC and its integration into the digital airborne aircraft complex ensured the operation of engines, included in the power plant provided with high specific fuel consumption, as well as increased the level of automation of the power plant control and monitoring, and ensured aircraft automation landing in ICAO category 3A. In addition, the use of the aforementioned electronic system, allowed to operate the power plant of the aircraft in accordance with technical status. The use of the AI-450-MS auxiliary power plant with an electronic control system such as FADEC, and the drive of the service compressor from a free turbine, eliminated the effect of changes in power and air takeoff, on the deviation of the engine from optimal mode, which also minimized the fuel consumption. The use of fuel metering system TIS-158, allowed to ensure control of its condition and assemblies, without the use of auxiliary devices, built-in control means. In the fire protection system, the use of the electronic control and monitor unit, as well as the use of digital serial code for the exchange of information between the elements of the system and the aircraft systems, has reduced the number of connections, which increased the reliability of the system and reduced its weight characteristics.

Research Progress of Key Technologies for Typical Reusable Launcher Vehicles

In recent years, driven by space X and other commercial companies, the requirement of low cost and fast response to transport, reusable launch vehicle technology is attracting the world’s attention. Aerospace agencies in various countries have stepped up research and made some progress in the related technologies of reusable launch vehicles. The development of reusable launch vehicle has become an important direction of space development in the future. First, the development status of reusable vehicles, the Space Shuttle Mode, the Falcon-9 Mode, the Launch Mode on board, and the Airborne Aircraft Mode, are introduced. Second, the structure design, the propulsion system, the recycling scheme, the thermal protection system and the launch costs of each mode is analyzed. Third, some related development suggestions are put forward in terms of the carrier configuration, the design of recycling scheme, the choose of propulsion system and the thermal protection system for reusable launch vehicle designer.