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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
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Transactions on Aerospace Research
Number of Followers: 3  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0509-6669 - ISSN (Online) 2545-2835
Published by Sciendo Homepage  [389 journals]
  • Vibroacoustic Helicopter Impact on Elevated Helipad

    • Abstract: A helicopter landing and taking off on an elevated helipad is a source of noise that affects the environment and causes vibrations of the landing pad or the building infrastructure. Vibrations are also excited by the air stream flowing through the main rotor and transferred to the landing pad by contact of the helicopter chassis. Vibrations are transferred to the building through the structure of the helipad. Depending on the damping properties of the structure and the vibro-isolating elements used, vibrations can be felt in rooms used by people and also transmitted to devices located in the building. the subject of the study described in this paper is the vibroacoustic effects of an eC-135 helicopter on an elevated landing pad during landing, standstill with the propulsion system engaged and take-off. Measurements of vibrations and noise were made at points located both on the landing pad and in the building. the paper presents selected results of measurements in various phases of flight and helicopter manoeuvres. the frequency analyses of the fragment of the measurement data for the flight phase, in which the highest levels of impact were recorded, were also performed and included. the results are presented as graphs and annotated.
      PubDate: Sat, 31 Dec 2022 00:00:00 GMT
  • Using the Pulsed Eddy Current Techniques for Monitoring the Aircraft
           Structure Condition

    • Abstract: It is known that during operation, the aircraft construction materials are exposed to significant mechanical loads and changes in temperature for a very short period of time. All this leads to various defects and damages in the aircraft assemblies and units that need to be inspected for the safe operation of the aircraft, their assemblies, and units. In some cases, the implementation of inspection or diagnostic is accompanied by the emergence of technical difficulties caused by the large size of the aircraft assemblies or units and limited access to their local places. Under such conditions, ensuring the possibility of diagnosis in hard-to-reach places of the object becomes especially important. The problem can be solved by applying wireless technologies. It allows spatial separation of the probes and the signal processing units, which simplifies the scanning of the surfaces of the large assemblies and units in hard-to-reach places. In this article, the description of the developed wireless system of eddy current inspection for aircraft structural materials is given. Experimental results of object scanning are given in the form of a distribution of the values of probe signal informative parameters (amplitude, frequency and decrement) along the object coordinates.
      PubDate: Sat, 31 Dec 2022 00:00:00 GMT
  • Optimisation of a Nacelle Electro-Thermal Ice Protection System for Icing
           Wind Tunnel Testing

    • Abstract: Aircraft are equipped with ice protection systems (IPS), to avoid, delay or remove ice accretion. Two widely used technologies are the thermo-pneumatic IPS and the electro-thermal IPS (ETIPS). Thermo-pneumatic IPS requires air extraction from the engine negatively affecting its performances. Moreover, in the context of green aviation, aircraft manufacturers are moving towards hybrid or fully electric aircraft requiring all electric on-board systems. In this work, an ETIPS has been designed and optimised to replace the nacelle pneumatic-thermal system. The aim is to minimise the power consumption while assuring limited or null ice formation and that the surface temperature remains between acceptable bounds to avoid material degradation. The design parameters were the length and heat flux of each heater. Runback ice formations and surface temperature were assessed by means of the in-house developed PoliMIce framework. The optimisation was performed using a genetic algorithm, and the constraints were handled through a linear penalty method. The optimal configuration required 33% less power with respect to the previously installed thermo-pneumatic IPS. Furthermore, engine performance is not affected in the case of the ETIPS. This energy saving resulted in an estimated reduction of specific fuel consumption of 3%, when operating the IPS in anti-icing mode.
      PubDate: Sat, 31 Dec 2022 00:00:00 GMT
  • The Simplest Models of the Macroeconomics Dynamics in a Composition with
           the Principle of the Subjective Entropy Maximum

    • Abstract: This paper proposes a solution to a certain macroeconomic model. A multi-alternative problem of aviation transportation optimal organisation in conditions of uncertainty of the subjective preference functions is considered. Conditional optimisation of the objective functional containing the entropy of the individuals’ operational effectiveness functions preferences is carried out in the framework of the simplest macroeconomic problem. The principle of the Solow and Cobb–Douglas models, similar to the approach adopted for the estimation of economic growth, is modified with the subjective entropy maximum principle. The advantages of the described optimisation approach are demonstrated in the generalised terms of the operational effectiveness functions for aviation transportation organisation.
      PubDate: Sat, 31 Dec 2022 00:00:00 GMT
  • The Role of Pegasus in the European Aeronautics and Space Universities
           Exchange of Students and Professors

    • Abstract: The objective of all universities in the Partnership of a European Group of Aeronautics and Space UniversitieS (PEGASUS) network is to offer highly relevant educational and research programmes and thereby attract the best students and scientists. Coordinated developments, exchange of students and staff and innovation are the basis on which these objectives are achieved. The paper shows how PEGASUS is contributing to the increase in students’ mobility among the partner universities, providing a tool to visualise, illustrate and quantify these flows. The tool provides a mapping of agreements and flows, using data based on a questionnaire sent to all PEGASUS partners. The data is available from the courses offered in the years 2012–2019 and has been prepared for display in the Google Earth application. It is a very flexible tool that allows for multiple searching criteria: per university of origin, per university of destination, per country, per course, etc. The current state of international exchange is shown, emphasising the noticed strengths and weaknesses. Initiatives taken to improve the weaknesses in cooperation are discussed and summed up with final conclusions.
      PubDate: Fri, 16 Dec 2022 00:00:00 GMT
  • Development of Turboshaft Engine Adaptive Dynamic Model: Analysis of
           Estimation Errors

    • Abstract: One of the most perspective directions of aircraft engine development is related to implementing adaptive automatic electronic control systems (ACS). The significant elements of these systems are algorithms of matching of mathematical models to actual performances of the engine. These adaptive models are used directly in control algorithms and are a combination of static and dynamic sub-models. This work considers the dynamic sub-models formation using the Least Square method (LSM) on a base of the engine parameters that are measured in-flight. While implementing this function in the (ACS), the problem of checking the sufficiency of the used information for ensuring the required precision of the model arises. We must do this checking a priori (to determine a set of operation modes, the shape of the engine test impact and volume of recorded information) and a posteriori. Equations of the engine models are considered. Relations are derived that determine the precision of parameters of these models’ estimation depending on the precision of measurement, the composition of the engine power ratings, and durability of observations, at a stepwise change of fuel flow. We present these relations in non-dimensional coordinates that make them universal and ready for application to any turboshaft engine.
      PubDate: Fri, 16 Dec 2022 00:00:00 GMT
  • An Analysis of the Spanish Aerospace Sector: The Case of the Start-Up
           Ecosystem in Madrid

    • Abstract: After launching the First Survey on the Spanish aerospace industry, important results were obtained, which helped to delve into the roots of the digital transformation (DT) of this sector, focussing on the Madrid region (Spain). From this type of study, which had not been carried out until now at the regional level, extremely interesting data have emerged that allow us to define the situation of Madrid companies in the aerospace sector. We have characterised and quantified the influence of what we have called ‘transformative enablers’. We have also analysed their relationships with the general characteristics of the companies, such as location, number of employees, legal form or type of company. We also obtained interesting conclusions about the role of respondents within organisations to discover the ‘capillarity’ of their situations and thus understand the degree of DT in terms of whether they achieve the so-called Industry 4.0 (Fourth Industrial Revolution) specifications. Finally, we have carried out a monographic study of the disruptive innovations within the start-up ecosystem to understand its definition and scope in the aerospace industry as a precursor of the latter’s DT.
      PubDate: Fri, 16 Dec 2022 00:00:00 GMT
  • A Systematic Review of Ground-Based Infrastructure for the Innovative
           Urban Air Mobility

    • Abstract: The increasing level of urbanisation and traffic congestion promotes the concept of urban air mobility (UAM), which has become a thriving topic in engineering and neighbouring disciplines. the development of a suitable ground-based infrastructure is necessary to supply these innovative vehicles, which mainly includes networks of take-off and landing sites, facilities for maintenance, energy supply, and navigation and communication capabilities. Further requirements comprise robust business and operating models for emerging service providers and regulatory frameworks, particularly regarding safety, liability and noise emissions. the objective of this study is to provide an overview of the current results and developments in the field of UAM ground-based infrastructure by conducting a systematic literature review (SLr) and to identify the most relevant research gaps in the field. For the systematic literature analysis, our search string contains vertiports and the equivalents, UAM and equivalents, and search phrases for the individual domains. In the final analysis 64 articles were included, finding a strong focus on simulations and vertiport networks, while specific case studies and related aspects like automated MrO and urban planning appear less frequently. therefore, this article provides insights for a more holistic perspective on challenges and necessities of future UAM.
      PubDate: Fri, 16 Dec 2022 00:00:00 GMT
  • Evolution of (AERO)Space Engineering Studies in Italy in the Past 20 Years

    • Abstract: The paper presents the evolution and trends in the Master’s-level studies in aerospace engineering in Italy, looking at the past 20 years. In the year 2000, a major reform of the higher education in engineering took place in Italy, with the introduction of the so-called ‘Bologna system’ and the clear separation of Bachelor’s and Master’s degree studies. With this reform, a relatively high flexibility was given to universities to define their programme structures. The ministerial rules defined only broad subject areas within which courses and credits should be allocated. This reform allowed the diversification of the educational profile within each university and, even more relevant, allowed the creation of mobility across the country between Bachelor’s and Master’s study programmes. The paper will show the basic facts and figures in the six Italian universities participating in the Partnership of a European Group of Aeronautics and Space UniversitieS (PEGASUS) network (Politecnico di Milano, Politecnico di Torino, Università di Pisa, Università degli Studi di Napoli ‘Federico II’, Sapienza Università di Roma and Alma Mater Studiorum – Università di Bologna), elaborating on the impact of the potential workforce for the sector. Data have been collected from the official open data repository of the Italian Ministry of University, supplemented by information provided by the six universities under analysis. The comparative analysis shows two major results: the positive impact of the reform on the overall Italian higher education and, specifically, a greater appreciation of the aerospace curricula proposed in accordance with the new system.
      PubDate: Fri, 16 Dec 2022 00:00:00 GMT
  • Science, Technology and Systems Engineering Educational Activities with
           Stratospheric Balloons

    • Abstract: In 2021, the Space Systems Laboratory of the University of Pisa (UniPi) started a student-oriented high-altitude ballooning programme intended to provide an opportunity for hands-on experience in support of the teaching of scientific and technical courses. The programme provides mentoring on scientific, technical and management issues, along with financial support and assistance with integration and launch on a sounding balloon platform. The goal is to conduct flying experiments in the stratosphere, retrieve them after landing and process the results; by doing so, the students experience all phases of a scientific mission project, from conceptual design to realisation, operations and post-flight analysis. Following a call for proposal open to all students of the UniPi across all study areas, three experiments were selected featuring multidisciplinary teams. This paper summarises the features of the programme’s first edition and presents the main lessons learned.
      PubDate: Fri, 16 Dec 2022 00:00:00 GMT
  • Holistic Low-Effort Model for Damage Tolerance Analysis in Preliminary

    • Abstract: The paper presents reduced order results for three different realistic scenarios with respect to the damage tolerance behaviour. The scenarios are dedicated to stiffened structures and feature the fuselage side panel, the upper fuselage panel and a lower wing panel. A wide range of parameter variations is discussed and the influence on the inspection interval is shown. Results may be used both in preliminary aircraft design and structural optimisation.
      PubDate: Tue, 27 Sep 2022 00:00:00 GMT
  • Easy Risk Assessment for Unmanned Aircraft Systems: Outline of the Method

    • Abstract: The key element of safety systems in air transport is risk management. The rules for the safety of unmanned aircraft system (UAS) operations are established by the Commission Implementing regulations (European Union [EU]) and national regulations. Risk assessment is the foundation of all activities. The broadest scope is covered by the special category of flights for which the Joint Authorities for rulemaking on Unmanned Systems (JARUS) developed the Specific Operations risk Assessment (SORA) analysis. The primary purpose of the SORA analysis is to create a comprehensive safety portfolio, which is attached to the National Aviation Authority (NAA) application for permission to perform specific category flights. Aviation authorities may accept the use of other risk analysis methods to demonstrate risk reduced to a safe level. Easy risk Assessment (erA) for UASs is an attempt to determine the risk for UAS flights in a simple way by considering a range of factors influencing risk management in a similar way to the SORA. It is an uncomplicated method, which determines threats and their sources, provides risk management, and allows the determination of the level of risk tolerance. The ERA is intended to be an alternative to the SORA methodology for those looking to carry out risk assessment.
      PubDate: Tue, 27 Sep 2022 00:00:00 GMT
  • Technique Used to Perform Rocket-Plane Free-Flight Tests

    • Abstract: This paper includes description of the technique that was applied for free-flight (drop) tests of the rocket-plane scaled model. The main aim of the experiment was to validate the numerical approach to be used to simulate the gliding flight of the rocket-plane, especially the transition between high to low angles of attack and the rocket-plane response to control. The primary goal of this paper is to show what kind of challenges must be addressed when planning the flight test campaign. This paper includes description of how the rocket-plane model was scaled and built, the model preparation, experimental design and flight procedure. This paper shows an overview of how the experiment can be planned for different scenarios and the lessons learned during the deep stall free-flight tests.
      PubDate: Tue, 27 Sep 2022 00:00:00 GMT
  • Fuel Weight Determination of Ultralight and Very Light Helicopters at the
           Preliminary Design Stage

    • Abstract: In recent years, a large number of one- to two-seat-type helicopters have appeared, raising the possibility to determine the dependencies inherent in these classes. Such dependencies are extremely necessary at the preliminary design stage, in particular, for determining the fuel mass. The relative mass of fuel depends on the required range and flight time of the helicopter, as well as on the characteristics of the engine and the required power of the helicopter. Based on statistical data, the article presents an approximate relation of the hourly fuel consumption of engines that small helicopters are equipped with. The additional amount of fuel required to complete missions has also been determined. General dependency of the fuel weight that can be used at the preliminary design stage is presented according to the analysis results.
      PubDate: Tue, 27 Sep 2022 00:00:00 GMT
  • Efficient Positioning of Two Long-Range Passenger Aircraft in Formation

    • Abstract: In today’s world, each airline is forced to look for new savings opportunities. One of the methods may be the use of formation flights in daily flight operations, which may allow a reduction in fuel consumption by several percentages. The paper presents the genesis of how the consideration of such flights and the possibility of their implementation in an airline had started. The leader’s plane generates vortices, which, with the proper alignment of the planes to one another, can reduce the drag on the wingman. However, the wrong position may not only have no positive effect but also may be a threat to stable wingman flight. The article presents a method of using these vortices in such a way as to have a positive impact on the aerodynamics of the wingman. A favourableposition in the vertical and horizontal axes will be determined in relation to the vortex generated by the leader’s plane in order to obtain the greatest benefit in reducing fuel consumption. The paper presents an operational analysis of the possibility of maintaining such a distance to obtain profit on fuel but also to ensure the highest level of safety of the flight.
      PubDate: Tue, 27 Sep 2022 00:00:00 GMT
  • Determination of the Geometric Properties of a Jet Engine Fan Blades Based
           on Modal Vibration Testing

    • Abstract: The article presents an experimental method of determining the geometric properties of jet engine rotor airfoils based on modal vibration testing. The procedure is based on adjusting the results of analytical calculations to the laboratory outcomes. Experimental tests were carried out on a set of 20 jet engine fan blades made of AL7022-t6 aluminium alloy. Each blade differed in weight and geometric dimensions within the accepted design tolerance. Numerical analysis of five airfoils that differed in thickness was performed. Modal vibration test results were summarised and compared with the results obtained by the numerical method. The comparison revealed a high similarity of the frequency and form of vibrations acquired by numerical simulation for each of the blades in relation to the executed vibration testing. Based on the verification of the theoretical model with the results obtained through experimental testing, conclusions were drawn about the object’s dynamic behaviour and its technological quality and geometric properties, whereby each of airfoil was probably thinned.
      PubDate: Tue, 27 Sep 2022 00:00:00 GMT
  • Eddy Current Techniques for Detecting Hidden Subsurface Defects in
           Multilayer Aircraft Structures

    • Abstract: In-service non-destructive inspection (NDI) is a very important part of the aircraft maintenance program that minimizes aircraft breakdowns due to the fracture of critical components. The eddy current (EC) NDI method is one of the most applicable methods for this purpose, due to its high sensitivity to fatigue cracks and corrosion damage in the main structural materials. In this paper, selective double differential type EC probes characterized by the enhanced possibility of detecting subsurface cracks initiated by fatigue or stress corrosion phenomena are presented. For different applications, a family of double differential type EC probes was developed with different sizes (from 5 to 33 mm) and different spatial resolutions. These types of probes are characterized by different operational frequencies in a wide frequency range (from 0.2 kHz to 1.0 MHz), high penetration depth and unique sensitivity to subsurface defects of different types (like elongated fatigue cracks or local corrosive pitting), and a high level of specific noise suppression concerned with the scanning inspection procedures. The EC probes proposed were investigated as effective tools for characteristic aircraft applications concerned with subsurface defect detection in multilayer structures, such as the detection of cracks in the second layer of a riveted two-layer structure or cracks initiated on the side surface of a multilayer structure with the suppression of the reinforcing hoop influence; the detection of subsurface defects in arc welding with a rough surface; the detection of cracks through repair patches fabricated from aluminum alloy or carbon fiber reinforced plastic, etc. These techniques create remarkable possibilities for the well-timed detection of dangerous damage without disassembling the aircraft structure or removing protective coating.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
  • Comparing Methods of Calculating Aircraft Engine Emissions of Harmful
           Exhaust Components During the Takeoff and Landing Cycle in the Airspace of
           an Airport

    • Abstract: An airport authority needs accurate information about the actual amount of harmful emissions being generated within its airspace, to be able to take measures leading to their reduction. This article presents two methods for estimating the amount of these emissions from aircraft engines during the take off and landing cycle (LTO) in the airspace of a medium-sized airport: one based on the total amount of the aircraft annually operated in it, and a second, more precise, one for a specific airline annually operating at this airport. The conclusions stemming from the comparison of these methods can support the introduction of operational and technical procedures reducing harmful emissions in the airport airspace during LTO cycle.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
  • Feasibility Study for a Fuel Cell-Powered Unmanned Aerial Vehicle with a
           75 Kg Payload

    • Abstract: Among the possible electric powerplants currently driving low-payload UAVs (up to around 10 kg of payload), batteries offer certain clear benefits, but for medium-payload operation such as aerotaxis and heavy-cargo transportation UAVs, battery capacity requirements restrict their usage due to high weight and volume. In light of this situation, fuel cell (FC) systems (FCS) offer clear benefits over batteries for the medium-payload UAV segment (> 50 kg). Nevertheless, studies regarding the application of FCS powerplants to this UAV segment are limited and the in-flight performance has not been clearly analysed. In order to address this knowledge gap, a feasibility analysis of these particular applications powered by FCS is performed in this study. A validated FC stack model (40 kW of maximum power) was integrated into a balance of plant to conform an FCS. As a novelty, the management of the FCS was optimized to maximize the FCS efficiency at different altitudes up to 12500 ft, so that the operation always implies the lowest H2 consumption regardless of the altitude. In parallel, an UAV numerical model was developed based on the ATLANTE vehicle and characterized by calculating the aerodynamic coefficients through CFD simulations. Then, both models were integrated into a 0D-1D modelling platform together with an energy management strategy optimizer algorithm and a suitable propeller model. With the preliminary results obtained from the FCS and UAV models, it was possible to ascertain the range and endurance of the vehicle. As a result, it was concluded that the combination of both technologies could offer a range over 600 km and an endurance over 5 h. Finally, with the integrated UAV-FCS model, a flight profile describing a medium altitude, medium endurance mission was designed and used to analyse the viability of FC-powered UAV. The results showed how UAVs powered by FCS are viable for the considered aircraft segment, providing competitive values of specific range and endurance.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
  • The Contribution of A. K. Oppenheim to Explaining the Nature of the
           Initiation of Gaseous Detonation in Tubes

    • Abstract: This paper analyzes A.K. Oppenheim’s original works on the transition of deflagration to detonation and reviews them from the perspective of new numerical and experimental results recently obtained on such phenomena. Particular attention is focused on processes happening in the boundary layer of the tube walls ahead of the accelerating flame. The results of the theoretical analyses of temperature variations inside developing boundary layer are presented and compared to the temperature variation in a free stream away from the boundary layer. Analyses of temperature increase in such layers clearly indicate that the self-ignition of the mixture happens in the boundary layer ahead of the propagating flame front. New experimental results obtained recently by a research group from the A. V. Luikov Heat and Mass Transfer Institute in Minsk, Belarus, combined with previously conducted theoretical analyses and numerical simulations, show clearly and unambiguously that the origin of the “explosion in the explosion”, postulated by A. K. Oppenheim in 1966, is always responsible for the Deflagration-Detonation Transition (DDT) in gases and is located in the boundary layer ahead of the accelerating flame front.
      PubDate: Thu, 23 Jun 2022 00:00:00 GMT
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