rss_2.0Transactions on Aerospace Research FeedSciendo RSS Feed for Transactions on Aerospace Research on Aerospace Research 's Cover Feature Extraction Algorithms Using Oscillatory-Mode Pulsed Eddy Current Techniques for Aircraft Structure Inspection<abstract> <title style='display:none'>Abstract</title> <p>A review of the existing literature shows that modern pulsed eddy current (PEC) technique for flaw detection in aircraft structure inspection is typically carried out in aperiodic mode. Аt the same time, the unstable characteristic points of the EC signal usually used as informative parameters can restrict the potential of this excitation mode due to significant measurement errors.</p> <p>This article considers an advanced PEC method of NDT based on the oscillatory mode. To obtain the conditions concerned with different modes of EC probe response oscillations, an equivalent scheme of the “testing object – EC probe” system was developed and analyzed. The frequency and attenuation coefficient of natural oscillations are proposed as the informative parameters of the probe signals. The obtained mathematical model of the probe signals allows for the dependence of proposed signal parameters on the characteristics of the testing object to be evaluated.</p> <p>Herein, we first develop algorithmic software for determining and analyzing the discrete amplitude and phase characteristics of PEC NDT signals based on the simulation results. The errors of the natural frequency oscillations and the attenuation coefficient determination as well as the optimal time for its determination are analyzed in order to minimize the possible errors. Next, the proposed informative parameters are experimentally investigated using a set of specimens. The obtained results confirm the possibility of the proposed methodology to enhance the inspection procedures related to the electrical conductivity and geometric parameters measurements as well as the detected defect sizing.</p> </abstract>ARTICLE2021-10-08T00:00:00.000+00:00Numerical Simulation of the Exit Temperature Pattern of an Aircraft Engine Using a Temperature-Dependent Turbulent Schmidt Number<abstract> <title style='display:none'>Abstract</title> <p>This paper presents a numerical simulation for predicting the combustor exit temperature pattern of an aircraft engine, developed using the commercial fluid simulation software Ansys Fluent, which assumes a shape probability density function for the instantaneous chemistry in the conserved scalar combustion model and the standard k-ε model for turbulence. We found the compliance of the radial and circumferential non-uniformities of the exit temperature with the experimental data to be insufficient. To achieve much more accurate result, the mixing intensity was enhanced with respect to the initial calculation due to using the reduced value of the turbulent Schmidt number Sc. Numerical simulation was performed for values of the turbulent Schmidt number from Sc = 0.85 (default) up to Sc = 0.2, with results confirming the reduction of radial and circumferential non-uniformities of exit temperature. However, correlation between radial and circumferential non-uniformities is not admissible for these cases. Therefore, we propose to use a temperature-dependent formulation of the turbulent Schmidt number Sc, accounting for the increase in Sc number with increasing gas temperature. A user defined function (UDF) was used to implement the Sc number temperature dependence in Ansys Fluent. The numerical results for the proposed Schmidt number Sc temperature dependence were found to be in acceptable agreement with the experimental data both for radial and circumferential non-uniformities of the exit temperature pattern.</p> </abstract>ARTICLE2021-10-08T00:00:00.000+00:00A Two-Point Approximation Approach to Determining Aircraft Aerodynamic Force Coefficients for a Maximal-Duration Horizontal Flight<abstract> <title style='display:none'>Abstract</title> <p>This paper proposes a two-point approximation approach to determining aircraft aerodynamic force coefficients, and compares it to the traditional methods. A variational concept is used to conduct aircraft flight trials for the maximal duration of quasi-horizontal flights. The advantages of the described optimization theories are demonstrated, in terms of aviation fuel gas savings. The results of a numerical example are presented.</p> </abstract>ARTICLE2021-10-08T00:00:00.000+00:00A Mathematical Model for Controlling a Quadrotor UAV<abstract> <title style='display:none'>Abstract</title> <p>Given the recent surge in interest in UAVs and their potential applications, a great deal of work has lately been done in the field of UAV control. However, UAVs belong to a class of nonlinear systems that are inherently difficult to control. In this study we devised a mathematical model for a PID (proportional integral derivative) control system, designed to control a quadrotor UAV so that it follows a predefined trajectory. After first describing quadrotor flight dynamics, we present the control model adopted in our system (developed in MATLAB Simulink). We then present simulated results for the use of the control system to move a quadrotor UAV to desired locations and along desired trajectories. Positive results of these simulation support the conclusion that a quadrotor UAV spatial orientation control system based on this model will successfully fulfil its task also in real conditions.</p> </abstract>ARTICLE2021-10-08T00:00:00.000+00:00Impact of Load Retention on Aircraft Engine Parts Under Real Flight Cycle Conditions in Service Life Monitoring<abstract> <title style='display:none'>Abstract</title> <p>One of the major problems in the development of algorithms for monitoring the life of aircraft gas turbine engines is that the character of loading in real flight cycles is crucially different from the character of the static and dynamic loading during the testing of samples. This paper proposes a method for taking into account the effect of retentions at maximum stresses and cycle temperatures on the low-cycle fatigue (LCF) of the heat-resistant alloys used in engine parts. Regularities in repeated-static loading (RSL) are used in combination with the method of linear accumulation of damage due to the LCF and RSL, with retentions of a variable length. A non-linear equation is derived for the summation of these damages, the solution of which determines the durability (life) of the part while taking into account the retention duration. The theoretical results were verified by using the experimental characteristics of the GS-6K and EI-437B nickel-based alloys, previously reported by other researchers.</p> </abstract>ARTICLE2021-10-08T00:00:00.000+00:00Numerical Investigation of Detonation Propagation Through Small Orifice Holes<abstract> <title style='display:none'>Abstract</title> <p>Seeking to better understand the physical phenomena underlying detonation wave propagation through small holes (especially the phenomenon of detonation re-initiation or its failure), we investigated the propagation of a detonation wave along a tube filled with a hydrogen-oxygen mixture diluted with argon, in the presence of obstacles with a small orifice hole. Numerical simulations were performed in a two-dimensional domain using adaptive mesh refinement and by solving compressible Euler equations for multiple thermally perfect species with a reactive source term. A premixed mixture of H<sub>2</sub>:O<sub>2</sub>:Ar at a ratio 2:1:7 at 10.0 kPa and 298 K was used in a 90 mm diameter tube with a detonation wave travelling from one end. We found that a single orifice placed at 200 mm from one end of the tube, with varying diameters of 6, 10, 14, 16, 18, 30, and 50 mm, showed an initial decoupling of the detonation wave into a shockwave and flame front. The detonation wave fails to propagate along the tube for orifice diameters less than <italic>λ</italic>, while it propagates by different re-initiation pathways for orifice diameters greater than <italic>λ</italic>, where <italic>λ</italic> is the cell-width for regular detonation propagation.</p> </abstract>ARTICLE2021-10-08T00:00:00.000+00:00Using Adverse Event Pyramids to Assess Probabilities in Airline Safety Management<abstract><title style='display:none'>Abstract</title><p>This article reviews the methods of safety management using Heinrich’s and Bird’s pyramids. The presence of a causal relationship between pyramid levels, as a result of inconsistencies in the activities of an organization and personnel, lead to incidents, and incidents in turn lead to accidents. The existence of such a relationship makes it possible to predict the risk of “top-level” events by reducing risks at the middle and lower levels. A mathematical description of the development process of an undesired aviation event is presented, which makes it possible to evaluate the probability of the successful (or unsuccessful) completion of a transportation task. Also given is an analysis of the development of an aviation accident, based on the example of the crash of a Lufthansa A-320 aircraft on 14 September 1993 at the airport of Warsaw (Poland) while landing in adverse weather conditions.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00An Alternative Ballistic Limit Equation for the Whipple Shield in the Shatter Regime, Based on Characteristics of the Large Central Fragment<abstract><title style='display:none'>Abstract</title><p>In the shatter regime of a Whipple shield, a large central fragment makes a significant contribution to the damage-causing capacity of the debris cloud. Herein we present a feasible scheme for the identification and measurement of this large central fragment and propose an alternative approach to the ballistic limit equation (BLE) for the Whipple shield, deducing an alternative ballistic limit in the shatter regime based on the large central fragment’s characteristics. This alternative BLE is compared with the phenomenological Whipple BLE, the JSC Whipple BLE and the Ryan curve. Our alternative BLE, modified at the incipient fragmentation and completed fragmentation point, is shown to agree well with experimental results.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Estimation of Bare Soil Moisture from Remote Sensing Indices in the 0.4–2.5 mm Spectral Range<abstract><title style='display:none'>Abstract</title><p>Soil moisture content (SMC) is an important element of the environment, influencing water availability for plants and atmospheric parameters, and its monitoring is important for predicting floods or droughts and for weather and climate modeling. Optical methods for measuring soil moisture use spectral reflection analysis in the 350–2500 nm range. Remote sensing is considered to be an effective tool for monitoring soil parameters over large areas and to be more cost effective than <italic>in situ</italic> measurements. The aim of this study was to assess the SMC of bare soil on the basis of hyperspectral data from the ASD FieldSpec 4 Hi-Res field spectrometer by determining remote sensing indices and visualization based on multispectral data obtained from UAVs. Remote sensing measurements were validated on the basis of field humidity measurements with the HH2 Moisture Meter and ML3 ThetaProbe Soil Moisture Sensor. A strong correlation between terrestrial and remote sensing data was observed for 7 out of 11 selected indexes and the determination coefficient R<sup>2</sup> values ranged from 67%– 87%. The best results were obtained for the NINSON index, with determination coefficient values of 87%, NSMI index (83.5%) and NINSOL (81.7%). We conclude that both hyperspectral and multispectral remote sensing data of bare soil moisture are valuable, providing good temporal and spatial resolution of soil moisture distribution in local areas, which is important for monitoring and forecasting local changes in climate.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Estimating Emissions of Harmful Exhaust Components by Aircraft Engines During the Takeoff and Landing Cycle in Airport Space<abstract><title style='display:none'>Abstract</title><p>This article examines, based on the available information and authors’ self-assessments, the environmental impact of turbine engine exhaust gases effect on the environment in the airport space during engines flight phases in the landing and takeoff cycle (LTO). The attention of aviation professionals is drawn to the fact that the amount of exhaust from the turbine engine is so significant that it may adversely change the ambient air at the airport. Consequently, increased emission level of carbon monoxide (CO), hydrocarbons (HC) during engine start-up and idle may pose a threat to the health of ramp staff. Also, high emission levels of nitrogen oxides (NO<sub>x</sub>) during takeoff, climb, cruise and descent is not without importance for the environment around the airport space. The paper gives CO<sub>2</sub>, HC, CO and NO<sub>x</sub> emission estimations based on ICAO Engine Emission Data Bank and the number of passenger operations at a medium-sized airport. It also provides calculation results of aircraft CO<sub>2</sub>, HC, CO and NO<sub>x</sub> emission using average times of aircraft maneuvers taken from aircraft Flight Data Recorder (FDR) in the LTO cycle various aircraft types at the airport. The latter, based on actual maneuvering times, lead to significantly reduced estimates of toxic exhaust gas emission volumes.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Preliminary Design for a Jet Training Aircraft<abstract><title style='display:none'>Abstract</title><p>This paper present the results of our project to develop the preliminary design of a jet trainer plane (JTP) with a two-person crew, the base version of which is intended for cadet training. We first consider the assumptions and requirements for the new aircraft, and review the parameters of existing aircraft designs in the similarly-purposed class. Next we argue for certain design choices, regarding the aircraft layout, cockpit configuration, wing location and wingform, tail scheme, and powerplant. The resulting aircraft design is calculated to have a maximum flight speed of 940 km/h, a ground-level rate of climb of 100 m/s, and a range of 1130 km. The plane’s take-off mass is calculated, in three approximations, at 2264 kg. Lastly we present the training plane’s geometrical parameters, general view, and master geometry.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Aerodynamic Characteristics of a Straight Wing with a Spiroid Wingtip Device<abstract><title style='display:none'>Abstract</title><p>Spiroid wingtip devices (WD) offer a promising way of improving the lift drag ratio of UAVs, but may on the other hand lead to negative aerodynamic interference of the wing with the WD and deterioration of the aerodynamic characteristics as compared to a wing without the WD. Determining the influence of the geometric parameters of a spiroid WD on aerodynamic wing characteristics, however, remains an understudied field. In our study, we investigated the influence of the following geometrical parameters on wing aerodynamic characteristics with WD: area, radius, camber angle, constriction, and pitch of the spiroid. We found that the positive effect of the WD is present at a relative radius &gt; 0.05, as well as with an increase in the lift coefficient <italic>C</italic><italic><sub>L</sub></italic> as a result of an increase in the proportion of inductive resistance. For example, with the Reynolds number Re = 2.1×10<sup>5</sup> for a rectangular wing with an aspect ratio <italic>θ</italic> = 5.12 equipped with a spiroid WD with =0.15 the quality gain is almost 10% at <italic>C</italic><italic><sub>L</sub></italic> = 0.5, and at <italic>C</italic><italic><sub>L</sub></italic> = 0.7 is almost 20% and at <italic>C</italic><italic><sub>L</sub></italic> = 0.7 – almost 20% compared to a wing without WD. Moreover, we found that a change in the camber angle WD <italic>θ</italic> provides an increase in the derivative of the lift coefficient with respect to the angle of attack in the range from <italic>θ</italic> = 0° to <italic>θ</italic> = 130°. By changing the camber angle, it is possible to increase the lift drag ratio of the layout up to 7.5% at <italic>θ</italic> = 90° compared to <italic>θ</italic> = 0° at the Reynolds number Re = 2.1×10<sup>5</sup>. From the point of view of ensuring maximum lift drag ratio and minimum inductive drag, the angle <italic>θ</italic> = 90° is the most beneficial.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Advanced Signal Processing Methods for Inspection of Aircraft Structural Materials<abstract> <title style='display:none'>Abstract</title> <p>Aircraft, their assemblies, and units must provide high durability and reliability, and maintain mechanical and technological characteristics throughout the life span of the aircraft. Different elements of aircraft structures work under mechanical loads, over a wide temperature range, with varying degrees of exposure to corrosive environments. Aircraft structural materials have a variation in the characteristics values and require the various testing methods for their inspection.</p> <p>In many NDT methods applied in aviation materials testing, signals that could be represented by a narrowband processes model are used. Known methods of their processing are focused on determining and analyzing the signals amplitude characteristics, but the information resource contained in phase characteristics is not used.</p> <p>In the article, the methodology for signal processing and determining phase characteristics in the time domain are discussed. It is based on the combination of the discrete Hilbert transform and the deterministic and statistical methods of the phase measurement. There are given examples of the application of the methodology for pulsed eddy current testing of electrically conductive materials and products, ultrasonic thickness measurement of products made of materials have significant ultrasonic attenuation, the realization impulse variant of acoustic impedance flaw detection of products made of composite materials. The examples have shown that the proposed signal processing methodology enables to determine new information parameters and signal characteristics for the industry, and extend the scope of known NDT methods.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Can we be with Bee on Mars? Evaluating the Impact of a Rocket Flight on the Condition of Honeybees ()<abstract> <title style='display:none'>Abstract</title> <p>In paper the issue of a rocket flight impact and overall survivability of such flight by <italic>Apis mellifera</italic> (western honeybees) specimens is raised. Author claims that it is the key for using them on Mars for pollination in future, as this species is considered as one of the best pollinators, and should be examined before sending first human missions to the Red Planet. Rocket payload ‘BeeO!Logical’ was designed in order to conduct the research, the first of its kind worldwide. Its assumptions are presented along with overall descriptions of the experiments in two sounding rockets. Analysed data included survivability, carbon dioxide concentration values (respiration levels), temperature and humidity. It has been shown that <italic>A. mellifera</italic> specimens are able to survive the rocket flight. Project development possibilities are described, including widening the scope of the research with bumblebees (<italic>Bombus</italic>) and implementation of biocybernetic model of bee colony.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Safety Critical Software Development Methodologies in Avionics<abstract> <title style='display:none'>Abstract</title> <p>This article summarizes avionics safety-critical software development methodologies and implications of the DO-178C standard from an Agile application perspective. We explain the safety-critical software categorization. It also outlines the main differences and advantages of different approaches to the development process, from Waterfall through the V-model to Iterative and Incremental. Agile principles are explained as well as a Scrum – which is a popular framework in the non-safety-critical software industry. The application of Agile, for safety-critical software considerations, is based on the practical knowledge of the authors, and looks at the potential solution from a DO-178C standard, size of the project, scalability, and organizational culture points of view. Definition of the Agile type of framework, consistent with the certification process and existing standards, has been highlighted as a potential game-changer for the avionics industry.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Detection of the Fatigue Cracks Initiated near the Rivet Holes by Eddy Current Inspection Techniques<abstract> <title style='display:none'>Abstract</title> <p>Eddy current (EC) method is considered as most applicable for in-service detection of fatigue subsurface cracks initiated in aircraft multilayer structures near the rivet holes. At the same time, the successful solution of this problem is obstructed by additional noise created by defect-free rivets. All EC inspection techniques for the detection of subsurface cracks around the rivets can be classified into three main groups: 1) static mode – carried out by placing the EC probe concentrically on the rivet head; 2) rotational mode – when the EC probe is rotated around the rivet axle and 2) sliding mode – performed by the movement of EC probe along the rivet line or near it. All these approaches have some advantages and limitations. In this study, known EC techniques for the detection of cracks in multilayer aircraft structures are analyzed. New advanced EC techniques for the detection of fatigue cracks in internal layers of the riveted structures based on different types (ring, sliding, and rotational) probes are presented. The static EC method with developed low-height ring-type probe creates the possibility to detect cracks in the difficult of access areas. The possibility to estimate the length of detected cracks by a ring-type probe is shown. The proposed rotational remote field EC probe can detect as small as 1.0 mm long cracks under the button-head rivet and 2 mm thick upper skin with a high signal-to-noise ratio. Therefore, in many aircraft structures, fatigue cracks will be detected before a critical threshold achieved. New EC sliding techniques based on remote field and double differential probes were proposed for the rapid detection of cracks in internal layers of riveted aircraft structures. Remote-field EC probe for reliable detection of fatigue cracks in third and fourth layers of five-layer units was proposed. Another sliding technique based on a double differential EC probe gives the possibility to detect transverse cracks in the second layer without the rivet row area access. The main advantage of developed techniques is high inspection reliability due to the possibility to discriminate the signals created by cracks and defect-free rivets. Presented inspection procedures include the selective signal analysis in the complex plane diagram. Proposed EC inspection techniques were successfully implemented into the aircraft maintenance practice.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00The User-Preferred Optimal Flight Parameters in an Active Navigational System in a Multi-Alternative Situation<abstract> <title style='display:none'>Abstract</title> <p>The goal of this paper is to investigate the influence of the objectively existing effectiveness functions of an aircraft control system upon the control and managerial decision making process in the framework of the subjective entropy maximum princi-ple. The subjective analysis theory entropy paradigm makes it possible to consider the aircraft control system based upon personal preferences as an active system governed by an individual (active element of the control system) with the help of her/his individual subjective preferences optimal distributions obtained in conditions of operational multi-alternativeness and those operational alternatives the active system active element’s individual subjective preferences uncertainty. The described ap-proach takes into account the simple two-alternative operational situation in regards with the objectively existing effectiveness functions, related to the aircraft control system, in the view of a controlled parameter and a combination of it with its rate as the ratio. The obtained expressions for the objective functional extremal functions of the effectiveness and preferences, as well as the subjective entropy of the alternatives preferences, illustrated in diagrams visualize the situation and allow taking a good choice. The ideas of the required proper governing, managing, and control methods choice optimization with respect to only 2 alternative objective effectiveness functions arguments might be simple; nevertheless, increasing the number of parameters and further complication of the problem setting will not change the principle of the problem solution.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00CFD Analysis of the Tractor Propulsion Concepts for an Inverted Joined Wing Airplane<abstract> <title style='display:none'>Abstract</title> <p>Efficiency is a crucial parameter for an airplane to reduce both cost of operations and emission of pollutants. There are several airplane concepts that potentially allow for increasing the efficiency. A few of them were not investigated thoroughly enough yet. The inverted joined wing configuration, with the upper wing in front of the lower one is an example of such concept. Therefore, a project consisting of development of an experimental scaled demonstrator, and its wind tunnel and flight testing, was undertaken by consortium: Institute of Aviation, Warsaw University of Technology, Air Force Institute of Technology and a MSP company. Results led to a conclusion, that the inverted joined wing configuration allows to build an airplane with excellent performance, but its advantage against the conventional airplane is marginal because of large trimming drag of the configuration with relatively high position of the thrust vector in pusher configuration. It was applied because the demonstrator was a flying model of manned airplane and the tractor configuration would affect the pilot’s field of observation. However, in case of the UAV, this reason becomes insignificant. Therefore two configurations of tractor propulsion were tested to see, if their performance is better than the performance of original design.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Heat Transfer Determined by the Temperature Sensitive Paint Method<abstract><title style='display:none'>Abstract</title><p>The paper presents practical aspects of determining the amount of heat flow by measuring the distribution of surface temperature using the Temperature Sensitive Paint (TSP) method. The quantity measured directly with TSP is the intensity of the excited radiation, which is then converted to surface temperature. The article briefly presents three different methods for determining the heat transfer coefficient. Each of these methods is based on a separate set of assumptions and significantly influences the construction of the measuring station. The advantages of each of the presented methods are their individual properties, allowing to improve accuracy, reduce the cost of testing or the possibility of using them in tests of highly complex objects. For each method a mathematical model used to calculate the heat transfer coefficient is presented. For the steady state heat transfer test method that uses a heater of constant and known thermal power, examples of the results of our own research are presented, together with a comparison of the results with available data and a discussion of the accuracy of the results obtained.</p></abstract>ARTICLE2019-09-06T00:00:00.000+00:00Increasingly Safe, High-Energy Propulsion System for Nano-Satellites<abstract><title style='display:none'>Summary</title><p>Numerous attempts have been undertaken to develop propulsion systems for nano-satellite-type spacecrafts to enable their maneuvering in orbits. One of the potentially viable chemical propellant propulsion systems is a hybrid system. The present paper studies propellant composition variants with the metal hydride as fuel that can be chosen for a nano-satellite hybrid propulsion system. It defines key requirements for chemical propellant nano-satellite propulsion systems, and specifies potential propellant pairs based on a compact metal hydride. The study describes basic technical characteristics of a 1U CubeSat propulsion system.</p></abstract>ARTICLE2019-09-06T00:00:00.000+00:00en-us-1