11th EASN International Conference on Innovation in Aviation & Space to the Satisfaction of the European Citizens

A special issue of Aerospace (ISSN 2226-4310).

Deadline for manuscript submissions: closed (15 January 2022) | Viewed by 77899

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Guest Editor
Honorary Chairman of the European Aeronautics Science Network Association (EASN), Head of the Laboratory of Technology and Strength of Materials, Department of Mechanical Engineering and Aeronautics, University of Patras, Panepistimioupolis Rion, 26500 Patras, Greece
Interests: aeronautical materials and structures; mechanical behaviour of materials; structural integrity; damage mechanics; experimental fracture mechanics; fatigue of aircraft materials and structures; ageing aircraft; characterization and manufacturing processes of polymers, thermosetting and thermoplastic composites; nanocomposites and nanocrystalline alloys; multifunctional and self-healing materials
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Guest Editor
Chairman of the European Aeronautics Science Network Association (EASN), Head of Department Aircraft Design, Institute of Aircraft Design (IFB), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart, Germany
Interests: aircraft design; conventional and unconventional configurations; aircraft systems; operational aspects; certification; electric and hybrid-electric flight; alternative propulsion systems; flight testing; unmanned aerial vehicles; scaled flight testing
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Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, SA, Italy
Interests: smart materials; study of the correlations between chemical-physical properties, structure, morphology and durability of macromolecular systems with different types of organizational architectures; design and development of new materials and materials applicable in the field of sensors; carbon–carbon composites (CCCs); thermosetting resins; mechanical properties; supramolecular interactions
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Special Issue Information

Dear Colleagues,

This Special Issue is cooperating with the 11th EASN International Conference on “Innovation in Aviation & Space to the Satisfaction of the European Citizens” (https://easnconference.eu), which will take place in Salerno, Italy from 1 to 4 September 2021. The conference venue will be located at the Fisciano Campus of the University of Salerno.

Like its predecessors, the 11th EASN International Conference will include a number of Plenary Talks by distinguished personalities of the European Aviation and Space sectors from academia, industry, the research community, and policy makers.

The event will also give an opportunity to scientists and researchers from all over the world to present their recent achievements in a series of thematic sessions, organized by internationally recognized scientists.

Furthermore, the conference is expected to be a major European Dissemination and Exploitation event of aviation- and space-related research, as it will provide a forum for presenting their activities and achieved goals, discussing on current trends and future needs of aviation- and space-related research and trying to identify possible synergies with each other. Additionally, a number of policy development projects will also find the floor to present the strategic priorities of the European aviation sector with regard to the challenges of FlightPath2050 and the expected “Horizon Europe” Framework Programme.  

The EASN Organizing Committee is working to organize a physical Conference in Salerno, Italy and there is confidence and optimism that, despite COVID-19, this will by then be a realistic scenario. Obviously, the EASN Team is also prepared for a hybrid or a fully virtual Conference as a backup solution in case it becomes necessary.

Authors of outstanding papers related to aviation and space are invited to submit extended versions of their work to this Special Issue for publication.

We look forward to welcoming you in Salerno and to making the 2021 EASN International Conference successful, and we welcome you to submit extended conference papers to this Special Issue.

Prof. Dr. Spiros Pantelakis
Prof. Dr. Andreas Strohmayer
Prof. Dr. Liberata Guadagno
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Aerospace is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Aerostructures: manufacturing
  • Aerostructures: materials
  • Flight physics
  • Propulsion
  • Small air transport (SAT) technologies
  • UAS and scaled flight testing
  • Avionics, systems, and equipment
  • Air traffic management and airports
  • Human factors
  • Innovative concepts and scenarios
  • Industry 4.0 and factories of the future
  • Space technologies
  • Space applications and operations
  • Space policies
  • ecoDESIGN and sustainable productivity
  • Environmental, recycling and disposal strategies
  • Safety, regulation and standards
  • Synergies and technology transfer with the automotive industry
  • European policy actions in the field of aviation and space

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Published Papers (20 papers)

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Editorial

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3 pages, 184 KiB  
Editorial
Special Issue “11th EASN International Conference on Innovation in Aviation & Space to the Satisfaction of the European Citizens”
by Liberata Guadagno, Spiros Pantelakis and Andreas Strohmayer
Aerospace 2022, 9(12), 808; https://doi.org/10.3390/aerospace9120808 - 9 Dec 2022
Viewed by 1165
Abstract
This Special Issue contains selected papers from works presented at the 11th EASN International Conference on “Innovation in Aviation & Space to the Satisfaction of the European Citizens” (http://easnconference [...] Full article

Research

Jump to: Editorial, Review

27 pages, 6323 KiB  
Article
Clean Sky 2 Technology Evaluator—Results of the First Air Transport System Level Assessments
by Marc Christopher Gelhausen, Wolfgang Grimme, Alf Junior, Christos Lois and Peter Berster
Aerospace 2022, 9(4), 204; https://doi.org/10.3390/aerospace9040204 - 9 Apr 2022
Cited by 7 | Viewed by 3025
Abstract
The authors have adjusted the DLR forecast model to evaluate the environmental benefits in terms of CO2 and NOx emissions of Clean Sky 2 technology innovations. The paper briefly describes the model employed: it consists of a passenger/flight volume forecast, a [...] Read more.
The authors have adjusted the DLR forecast model to evaluate the environmental benefits in terms of CO2 and NOx emissions of Clean Sky 2 technology innovations. The paper briefly describes the model employed: it consists of a passenger/flight volume forecast, a fleet model, and emission modelling. The novelty of the forecast approach compared to previous studies is that it is based on airport pairs instead of larger aggregates like countries or regions. Therefore, a separate breakdown on airports is unnecessary in the case of a more detailed analysis is needed, and it enables us to include airport capacity constraints which affect demand and flight volume, as well as the fleet development at constrained and unconstrained airports. We eventually present the forecast results in terms of passenger and flight volume, fleet development, and CO2 and NOx emissions. The results show that emissions can be reduced substantially by the use of Clean Sky 2 technology compared to a reference case which represents the status quo. Full article
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12 pages, 5252 KiB  
Article
The Impact of Sensor Errors on Flight Stability
by Michal Welcer, Cezary Szczepański and Mariusz Krawczyk
Aerospace 2022, 9(3), 169; https://doi.org/10.3390/aerospace9030169 - 19 Mar 2022
Cited by 10 | Viewed by 2718
Abstract
Sensors play a significant role in flight control systems. The accuracy of the measurements of state variables affects the quality and effectiveness of flight stabilization. When designing closed-loop systems, it is desirable to use sensors of the highest class and reliability, the signals [...] Read more.
Sensors play a significant role in flight control systems. The accuracy of the measurements of state variables affects the quality and effectiveness of flight stabilization. When designing closed-loop systems, it is desirable to use sensors of the highest class and reliability, the signals of which will be as error-free as possible. False indications lead to malfunctioning of the stabilization system, and its operation does not meet the requirements set for it. There are many types of errors—bias, white noise, hysteresis, or bias drift—which affect the measurement signals from the sensors. One of the significant problems is assessing what maximum level of sensor errors stabilization system will still operate as required. In this paper, the impact of different sensor errors on flight stabilization was presented. The research was carried out using the example of an automatic flight stabilization system using aircraft trimming surfaces in a longitudinal control channel in Hardware-in-the-Loop simulations. The model simulates various types of sensor errors during flight, while the stabilization system is implemented in hardware interfaced with a real-time computer. The results of the simulations are presented and analyzed. Their comparison indicated which sensor errors affects the flight stability the most and how the effectiveness of the stabilization system changes as error increases. The presented results show changes in flight parameters due to added sensor errors. Depending on the accuracy class of the IMU, the errors more or less disrupt the operation of the system. Full article
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34 pages, 4708 KiB  
Article
Application of Probabilistic Set-Based Design Exploration on the Energy Management of a Hybrid-Electric Aircraft
by Andrea Spinelli, Hossein Balaghi Enalou, Bahareh Zaghari, Timoleon Kipouros and Panagiotis Laskaridis
Aerospace 2022, 9(3), 147; https://doi.org/10.3390/aerospace9030147 - 8 Mar 2022
Cited by 12 | Viewed by 4190
Abstract
The energy management strategy of a hybrid-electric aircraft is coupled with the design of the propulsion system itself. A new design space exploration methodology based on Set-Based Design is introduced to analyse the effects of different strategies on the fuel consumption, NOx [...] Read more.
The energy management strategy of a hybrid-electric aircraft is coupled with the design of the propulsion system itself. A new design space exploration methodology based on Set-Based Design is introduced to analyse the effects of different strategies on the fuel consumption, NOx and take-off mass. Probabilities are used to evaluate and discard areas of the design space not capable of satisfying the constraints and requirements, saving computational time corresponding to an average of 75%. The study is carried on a 50-seater regional turboprop with a parallel hybrid-electric architecture. The strategies are modelled as piecewise linear functions of the degree of hybridisation and are applied to different mission phases to explore how the strategy complexity and the number of hybridised segments can influence the behaviour of the system. The results indicate that the complexity of the parametrisation does not affect the trade-off between fuel consumption and NOx emissions. On the contrary, a significant trade-off is identified on which phases are hybridised. That is, the least fuel consumption is obtained only by hybridising the longest mission phase, while less NOx emissions are generated if more phases are hybridised. Finally, the maximum take-off mass was investigated as a parameter, and the impact to the trade-off between the objectives was analysed. Three energy management strategies were suggested from these findings, which achieved a reduction to the fuel consumption of up to 10% and a reduction to NOx emissions of up to 15%. Full article
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22 pages, 30404 KiB  
Article
Automated Piping in an Airbus A320 Landing Gear Bay Using Graph-Based Design Languages
by Moritz Neumaier, Stefan Kranemann, Bernd Kazmeier and Stephan Rudolph
Aerospace 2022, 9(3), 140; https://doi.org/10.3390/aerospace9030140 - 5 Mar 2022
Cited by 5 | Viewed by 4679
Abstract
System design in an aircraft is still a costly, manual and iterative approach. One major cost driver of changes in system installation are design efforts for creating new pipes in an earlier stage and the costs accumulated during the in service life. To [...] Read more.
System design in an aircraft is still a costly, manual and iterative approach. One major cost driver of changes in system installation are design efforts for creating new pipes in an earlier stage and the costs accumulated during the in service life. To reduce these costs and the time to market, an automation approach with an integrated design optimization encoded in graph-based design languages and executable in a design compiler is proposed. To generate the pipe work automatically, a set of input data (e.g., start- and end-points of a pipe with tangents and fixing positions) is given by the user. It also contains, among others, the weightings for the optimization criteria (e.g., length of the pipe resp. the weight vs. the number of bends) to influence the evaluation of the generated pipes and thereby the final solution. As an initial step in the automatic pipe generation process, a route through the installation space is searched. Subsequently, the installation space is simplified and a respective minimal distance to each obstacle which a pipe should satisfy is added. Then for each pipe an initial solution is estimated and each pipe is optimized by a simulated annealing algorithm. At last, all given requirements are automatically verified. A carried out investigation indicates a polynomial runtime behaviour of the algorithm. The capabilities of the newly developed automated piping are demonstrated on the pipe work in an Airbus A320 landing gear bay. Full article
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14 pages, 3746 KiB  
Article
Compressive Behaviour of 3D-Printed PETG Composites
by Sara Valvez, Abílio P. Silva and Paulo N. B. Reis
Aerospace 2022, 9(3), 124; https://doi.org/10.3390/aerospace9030124 - 28 Feb 2022
Cited by 32 | Viewed by 5957
Abstract
It is known that 3D-printed PETG composites reinforced with carbon or Kevlar fibres are materials that can be suitable for specific applications in the aeronautical and/or automotive sector. However, for this purpose, it is necessary to understand their mechanical behaviour, which is not [...] Read more.
It is known that 3D-printed PETG composites reinforced with carbon or Kevlar fibres are materials that can be suitable for specific applications in the aeronautical and/or automotive sector. However, for this purpose, it is necessary to understand their mechanical behaviour, which is not yet fully understood in terms of compression. Therefore, this study intends to increase the knowledge in this domain, especially in terms of static behaviour, as well as with regard to creep and stress relaxation due to the inherent viscoelasticity of the matrix. In this context, static, stress relaxation and creep tests were carried out, in compressive mode, using neat PETG and PETG composites reinforced with carbon and Kevlar fibres. From the static tests, it was found that the yield compressive strength decreased in both composites compared to the neat polymer. Values around 9.9% and 68.7% lower were found, respectively, when carbon and Kevlar fibres were added to the PETG. Similar behaviour was observed for compressive displacement, where a reduction of 20.4% and 46.3% was found, respectively. On the other hand, the compressive modulus increased by 12.4% when carbon fibres were added to the PETG matrix and decreased by 39.6% for Kevlar fibres. Finally, the stress relaxation behaviour revealed a decrease in compressive stresses over time for neat PETG, while the creep response promoted greater compressive displacement. In both situations, the response was very dependent on the displacement/stress level used at the beginning of the test. However, when the fibres were added to the polymer, higher stress relaxations and compressive displacements were observed. Full article
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18 pages, 19184 KiB  
Article
Intelligent Combined Neural Network and Kernel Principal Component Analysis Tool for Engine Health Monitoring Purposes
by Maria Grazia De Giorgi, Luciano Strafella, Nicola Menga and Antonio Ficarella
Aerospace 2022, 9(3), 118; https://doi.org/10.3390/aerospace9030118 - 24 Feb 2022
Cited by 15 | Viewed by 2533
Abstract
An efficient maintenance plan is an important aspect for aeronautical companies to increase flight safety and decrease costs. Modern technologies are widely used in the Engine Health Monitoring (EHM) discipline to develop intelligent tools capable of monitoring the health status of engines. In [...] Read more.
An efficient maintenance plan is an important aspect for aeronautical companies to increase flight safety and decrease costs. Modern technologies are widely used in the Engine Health Monitoring (EHM) discipline to develop intelligent tools capable of monitoring the health status of engines. In this work, Artificial Neural Networks (ANNs) and in-detail Feed-Forward Neural Networks (FFNNs) were exploited in addition to a Kernel Principal Component Analysis (KPCA) to design an intelligent diagnostic tool capable of predicting the Performance Parameters (PPs) of the main components used as their health index. For this purpose, appropriate datasets containing information about degraded engines were generated using the Gas Turbine Simulation Program (GSP). Finally, the original datasets and the reduced datasets obtained after the application of KPCA to the original datasets were both used in the training and testing process of neural networks, and results were compared. The goal was to obtain a reliable intelligent tool useful for diagnostic purposes. The study showed that the degraded component detection and estimation of its performance achieved by using the hybrid KPCA–FFNNs were predicted with accurate and reliable performance, as demonstrated through detailed quantitative confusion matrix analysis. Full article
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19 pages, 6856 KiB  
Article
Simulation of Runway Irregularities in a Novel Test Rig for Fully Electrical Landing Gear Systems
by Andrea De Martin, Giovanni Jacazio and Massimo Sorli
Aerospace 2022, 9(2), 114; https://doi.org/10.3390/aerospace9020114 - 21 Feb 2022
Cited by 5 | Viewed by 2756
Abstract
The E-LISA research project, under way within the Clean Sky 2 framework, has the objective of developing an innovative iron bird dedicated to executing tests on the landing gear of a small aircraft transport equipped with an electro-mechanical landing gear and electrical brake. [...] Read more.
The E-LISA research project, under way within the Clean Sky 2 framework, has the objective of developing an innovative iron bird dedicated to executing tests on the landing gear of a small aircraft transport equipped with an electro-mechanical landing gear and electrical brake. Such tests include the simulation of complete landing procedures under different operating conditions such as runway friction, presence of periodical defects along the runway, variable aircraft weight, and approach speed. To this end, the iron bird requires novel solutions in both its architecture and its control scheme. This paper details an innovative solution that is being implemented in the E-LISA iron bird to enable the execution of tests on a landing gear, reproducing the effects of any type of runway irregularity. First, the rig architecture is presented in detail, with particular care toward the hybrid position/force control system that manages its operations. Then, a simulation model is introduced with the objective of verifying the control system stability and the test rig capability to reproduce on the test articles the effects produced on the landing gear leg of periodical runway irregularities. Simulations results are presented, highlighting the stability of the proposed control scheme and providing a preliminary assessment of the system performances. Full article
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11 pages, 5450 KiB  
Article
Pre-Flight Test Verification of Automatic Stabilization System Using Aircraft Trimming Surfaces
by Albert Zajdel, Mariusz Krawczyk and Cezary Szczepański
Aerospace 2022, 9(2), 111; https://doi.org/10.3390/aerospace9020111 - 19 Feb 2022
Cited by 3 | Viewed by 2859
Abstract
The new requirement of installing the flight stabilization system onboard the airplanes for performing the single-pilot flights in IFR rules was issued lately. It caused the necessity of developing such a system for small aircraft. The proposed system was developed using Model-Based Design [...] Read more.
The new requirement of installing the flight stabilization system onboard the airplanes for performing the single-pilot flights in IFR rules was issued lately. It caused the necessity of developing such a system for small aircraft. The proposed system was developed using Model-Based Design then tuned and tested in Model, Pilot and Hardware in the Loop Simulations. The paper presents the next advanced stage of testing—verification in simulation and ground tests on the PZL-130 Orlik airplane. The implementation of this system does not modify the pilot’s primary manual controls. The newly introduced electrical trim is used for automatic stabilization but can be used at manual trimming as it was previously, depending on the chosen operation mode. The ground tests were planned according to civil aviation authority and aviation law requirements. Chosen results from simulated flights were analyzed and presented, confirming the effectiveness of the proposed system. The dedicated application allowing the test engineer to change stabilization system parameters during the flight on a touchscreen tablet was developed and described. The outcome of the stabilization system test campaign was a verification of its performance before the flight tests. The comparison of simulated and real flight data will allow identifying model deficiencies and flight stabilization system efficiency, which makes possible improvements implementation. Additionally, it appeared to be the cost-effective and less electrical energy-consuming automatic flight stabilization system for small aircraft. Such features benefit initiatives like Future Sky, More Electric Aircraft and aircraft stabilization system retrofit. Full article
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13 pages, 3672 KiB  
Article
Electro-Thermal Parameters of Graphene Nano-Platelets Films for De-Icing Applications
by Khitem Lahbacha, Sarah Sibilia, Gianmarco Trezza, Gaspare Giovinco, Francesco Bertocchi, Sergio Chiodini, Francesco Cristiano and Antonio Maffucci
Aerospace 2022, 9(2), 107; https://doi.org/10.3390/aerospace9020107 - 16 Feb 2022
Cited by 6 | Viewed by 2189
Abstract
This paper provides a study of some relevant electro-thermal properties of commercial films made by pressed graphene nano-platelets (GNPs), in view of their use as heating elements in innovative de-icing systems for aerospace applications. The equivalent electrical resistivity and thermal emissivity were studied, [...] Read more.
This paper provides a study of some relevant electro-thermal properties of commercial films made by pressed graphene nano-platelets (GNPs), in view of their use as heating elements in innovative de-icing systems for aerospace applications. The equivalent electrical resistivity and thermal emissivity were studied, by means of models and experimental characterization. Macroscopic strips with a length on the order of tens of centimeters were analyzed, either made by pure GNPs or by composite mixtures of GNPs and a small percentage of polymeric binders. Analytical models are derived and experimentally validated. The thermal response of these graphene films when acting as a heating element is studied and discussed. Full article
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17 pages, 1238 KiB  
Article
Enhancement Opportunities for Conceptual Design in Aerospace Based on the Advanced Morphological Approach
by Vladislav T. Todorov, Dmitry Rakov and Andreas Bardenhagen
Aerospace 2022, 9(2), 78; https://doi.org/10.3390/aerospace9020078 - 1 Feb 2022
Cited by 6 | Viewed by 1917
Abstract
The current challenges facing the aerospace domain require unconventional solutions, which could be sought in new configurations of future aircraft and spacecraft. The choice of optimal concepts requires the consideration of a significant amount of competing engineering solutions and takes place under conditions [...] Read more.
The current challenges facing the aerospace domain require unconventional solutions, which could be sought in new configurations of future aircraft and spacecraft. The choice of optimal concepts requires the consideration of a significant amount of competing engineering solutions and takes place under conditions of uncertainty. Such a problem can be addressed by enhancing existing methods for analysis and synthesis solutions, such as the Advanced Morphological Approach (AMA). It uses morphological analysis to provide a more exhaustive overview of possible problem solutions, relies on expert evaluations of alternative technological options and applies clustering to the solution space. Although an intuitive method for structured concept generation, the AMA exposes the need for more robust problem structuring, improved objectivity of options evaluation and accounting for uncertainties. The current article suggests ways to overcome these challenges and their possible integration in the process. In particular, the integration of fuzzy sets is proposed to model uncertainties during the evaluation of technological options by the experts. The Fuzzy Analytical Hierarchy Process is adapted for integration into the AMA and for the conceptual design of aerospace vehicles. Full article
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38 pages, 21367 KiB  
Article
Initial Assessment of a Fuel Cell—Gas Turbine Hybrid Propulsion Concept
by Arne Seitz, Markus Nickl, Florian Troeltsch and Kathrin Ebner
Aerospace 2022, 9(2), 68; https://doi.org/10.3390/aerospace9020068 - 26 Jan 2022
Cited by 15 | Viewed by 5128
Abstract
A fuel cell—gas turbine hybrid propulsion concept is introduced and initially assessed. The concept uses the water mass flow produced by a hydrogen fuel cell in order to improve the efficiency and power output of the gas turbine engine through burner steam injection. [...] Read more.
A fuel cell—gas turbine hybrid propulsion concept is introduced and initially assessed. The concept uses the water mass flow produced by a hydrogen fuel cell in order to improve the efficiency and power output of the gas turbine engine through burner steam injection. Therefore, the fuel cell product water is conditioned through a process of condensation, pressurization and re-vaporization. The vaporization uses the waste heat of the gas turbine exhaust. The functional principles of the system concept are introduced and discussed, and appropriate methodology for an initial concept evaluation is formulated. Essential technology fields are surveyed in brief. The impact of burner steam injection on gas turbine efficiency and sizing is parametrically modelled. Simplified parametric models of the fuel cell system and key components of the water treatment process are presented. Fuel cell stack efficiency and specific power levels are methodically derived from latest experimental studies at the laboratory scale. The overall concept is assessed for a liquid hydrogen fueled short-/medium range aircraft application. Block fuel savings of up to 7.1% are found for an optimum design case based on solid oxide fuel cell technology. The optimum design features a gas turbine water-to-air ratio of 6.1% in cruise and 62% reduced high-level NOx emissions. Full article
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18 pages, 2998 KiB  
Article
Design of an ATC Tool for Conflict Detection Based on Machine Learning Techniques
by Javier Alberto Pérez-Castán, Luis Pérez-Sanz, Lidia Serrano-Mira, Francisco Javier Saéz-Hernando, Irene Rodríguez Gauxachs and Víctor Fernando Gómez-Comendador
Aerospace 2022, 9(2), 67; https://doi.org/10.3390/aerospace9020067 - 26 Jan 2022
Cited by 12 | Viewed by 4088
Abstract
Given the ongoing interest in the application of Machine Learning (ML) techniques, the development of new Air Traffic Control (ATC) tools is paramount for the improvement of the management of the air transport system. This article develops an ATC tool based on ML [...] Read more.
Given the ongoing interest in the application of Machine Learning (ML) techniques, the development of new Air Traffic Control (ATC) tools is paramount for the improvement of the management of the air transport system. This article develops an ATC tool based on ML techniques for conflict detection. The methodology develops a data-driven approach that predicts separation infringements between aircraft within airspace. The methodology exploits two different ML algorithms: classification and regression. Classification algorithms denote aircraft pairs as a Situation of Interest (SI), i.e., when two aircraft are predicted to cross with a separation lower than 10 Nautical Miles (NM) and 1000 feet. Regression algorithms predict the minimum separation expected between an aircraft pair. This data-driven approach extracts ADS-B trajectories from the OpenSky Network. In addition, the historical ADS-B trajectories work as 4D trajectory predictions to be used as inputs for the database. Conflict and SI are simulated by performing temporary modifications to ensure that the aircraft pierces into the airspace in the same time period. The methodology is applied to Switzerland’s airspace. The results show that the ML algorithms could perform conflict prediction with high-accuracy metrics: 99% for SI classification and 1.5 NM for RMSE. Full article
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16 pages, 5643 KiB  
Article
Plasma Assisted Re-Ignition of Aeroengines under High Altitude Conditions
by Ghazanfar Mehdi, Sara Bonuso and Maria Grazia De Giorgi
Aerospace 2022, 9(2), 66; https://doi.org/10.3390/aerospace9020066 - 26 Jan 2022
Cited by 8 | Viewed by 2303
Abstract
Re-ignition of aeroengines under high altitude conditions is of great importance to the safety and use of lean-burn flame. This study is focused on the experimental and numerical characterization of flow dynamics and flame re-ignition in a rectangular burner. A ring-needle type plasma [...] Read more.
Re-ignition of aeroengines under high altitude conditions is of great importance to the safety and use of lean-burn flame. This study is focused on the experimental and numerical characterization of flow dynamics and flame re-ignition in a rectangular burner. A ring-needle type plasma actuator was considered and run by high-voltage (HV) nanopulsed plasma generator. The electrical power delivered to the fluid and an optimal value of reduced electric field (EN) was calculated considering non-reactive flow. Smoke flow visualizations using a high-speed camera and proper orthogonal decomposition (POD) were performed to recognize the most dominant flow structures. Experimental results revealed the transport effects due to plasma discharge, such as the induced flow, that could have a strong impact on the recirculation zone near the corners of combustor, improving the mixing performance and reducing the ignition delay time. Two different numerical tools (ZDPlasKin and Chemkin) were used to investigate the ignition characteristics. ZDPlasKin calculated the thermal effect and the plasma kinetic of nanopulsed plasma discharge at the experimentally measured EN. Finally, based on the output of ZDPlasKin, Chemkin estimated the flame ignition at low pressure and low temperature conditions. It was noticed that time required to achieve the maximum flame temperature with plasma actuation is significantly less than the auto-ignition time (‘clean case’, simulation result of the model without considering the plasma effect). Maximum reduction in ignition time was observed at inlet pressure 1 bar (3.5 × 10−5 s) with respect to the clean case (1.1 × 10−3 s). However, as the inlet pressure is reduced, the ignition delay time was increased. At 0.6 bar flame ignition occurred in clean case at 0.0048 s and at 0.0022 s in presence of the plasma actuation, a further decrease of the pressure up to 0.4 bar leads the ignition at 0.0027 s and 0.0063 s in clean and plasma actuation, respectively. Full article
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18 pages, 2511 KiB  
Article
Model-Based Dynamic Performance Simulation of a Microturbine Using Flight Test Data
by Mario Leonardo Erario, Maria Grazia De Giorgi and Radoslaw Przysowa
Aerospace 2022, 9(2), 60; https://doi.org/10.3390/aerospace9020060 - 24 Jan 2022
Cited by 8 | Viewed by 3858
Abstract
Microturbines can be used not only in models and education but also to propel UAVs. However, their wider adoption is limited by their relatively low efficiency and durability. Validated simulation models are required to monitor their performance, improve their lifetime, and to design [...] Read more.
Microturbines can be used not only in models and education but also to propel UAVs. However, their wider adoption is limited by their relatively low efficiency and durability. Validated simulation models are required to monitor their performance, improve their lifetime, and to design engine control systems. This study aims at developing a numerical model of a micro gas turbine intended for prediction and prognostics of engine performance. To build a reliable zero-dimensional model, the available compressor and turbine maps were scaled to the available test bench data with the least squares method, to meet the performance of the engine achieved during bench and flight tests. A steady-state aeroengine model was implemented in the Gas turbine Simulation Program (GSP) and was compared with experimental operating points. The selected flight data were then used as input for the transient engine model. The exhaust gas temperature (EGT) and fuel flow were chosen as the two key parameters to validate the model, comparing the numerical predicted values with the experimental ones. The observed difference between the model and the flight data was lower than 3% for both EGT and fuel flow. Full article
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18 pages, 1520 KiB  
Article
Wing Structural Model for Overall Aircraft Design of Distributed Electric Propulsion General Aviation and Regional Aircraft
by Raquel Alonso Castilla, Florent Lutz, Joël Jézégou and Emmanuel Bénard
Aerospace 2022, 9(1), 5; https://doi.org/10.3390/aerospace9010005 - 22 Dec 2021
Cited by 7 | Viewed by 6703
Abstract
In the context of reducing the environmental footprint of tomorrow’s aviation, Distributed Electric Propulsion (DEP) has become an increasingly interesting concept. With the strong coupling between disciplines that this technology brings forth, multiple benefits are expected for the overall aircraft design. These interests [...] Read more.
In the context of reducing the environmental footprint of tomorrow’s aviation, Distributed Electric Propulsion (DEP) has become an increasingly interesting concept. With the strong coupling between disciplines that this technology brings forth, multiple benefits are expected for the overall aircraft design. These interests have been observed not only in the aerodynamic properties of the aircraft but also in the structural design. However, current statistical models used in conceptual design have shown limitations regarding the benefits and challenges coming from these new design trends. As for other methods, they are either not adapted for use in a conceptual design phase or do not cover CS-23 category aircraft. This paper details a semi-analytical methodology compliant with the performance-based certification criteria presented by the European Union Aviation Safety Agency (EASA) to predict the structural mass breakdown of a wing. This makes the method applicable to any aircraft regulated by EASA CS-23. Results have been validated with the conventional twin-engine aircraft Beechcraft 76, the innovative NASA X-57 Maxwell concept using DEP, and the commuter aircraft Beechcraft 1900. Full article
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34 pages, 5525 KiB  
Article
Multi-Fidelity Optimization of a Composite Airliner Wing Subject to Structural and Aeroelastic Constraints
by Angelos Kafkas, Spyridon Kilimtzidis, Athanasios Kotzakolios, Vassilis Kostopoulos and George Lampeas
Aerospace 2021, 8(12), 398; https://doi.org/10.3390/aerospace8120398 - 15 Dec 2021
Cited by 9 | Viewed by 3209
Abstract
Efficient optimization is a prerequisite to realize the full potential of an aeronautical structure. The success of an optimization framework is predominately influenced by the ability to capture all relevant physics. Furthermore, high computational efficiency allows a greater number of runs during the [...] Read more.
Efficient optimization is a prerequisite to realize the full potential of an aeronautical structure. The success of an optimization framework is predominately influenced by the ability to capture all relevant physics. Furthermore, high computational efficiency allows a greater number of runs during the design optimization process to support decision-making. The efficiency can be improved by the selection of highly optimized algorithms and by reducing the dimensionality of the optimization problem by formulating it using a finite number of significant parameters. A plethora of variable-fidelity tools, dictated by each design stage, are commonly used, ranging from costly high-fidelity to low-cost, low-fidelity methods. Unfortunately, despite rapid solution times, an optimization framework utilizing low-fidelity tools does not necessarily capture the physical problem accurately. At the same time, high-fidelity solution methods incur a very high computational cost. Aiming to bridge the gap and combine the best of both worlds, a multi-fidelity optimization framework was constructed in this research paper. In our approach, the low-fidelity modules and especially the equivalent-plate methodology structural representation, capable of drastically reducing the associated computational time, form the backbone of the optimization framework and a MIDACO optimizer is tasked with providing an initial optimized design. The higher fidelity modules are then employed to explore possible further gains in performance. The developed framework was applied to a benchmark airliner wing. As demonstrated, reasonable mass reduction was obtained for a current state of the art configuration. Full article
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17 pages, 8150 KiB  
Article
Investigation of the Impact of a Particle Foam Insulation on Airflow, Temperature Distribution, Pressure Profile and Frost Buildup on the Aircraft Structure
by Victor Norrefeldt and Gerhard Riedl
Aerospace 2021, 8(12), 359; https://doi.org/10.3390/aerospace8120359 - 23 Nov 2021
Cited by 4 | Viewed by 2851
Abstract
Aircraft insulation separates the thermally comfortable cabin interior environment from the extremely cold outside conditions. However, the fabrication and installation of the insulation in the aircraft is a labor-intensive task. Tailored, rigid particle foam parts could be a solution to speed up the [...] Read more.
Aircraft insulation separates the thermally comfortable cabin interior environment from the extremely cold outside conditions. However, the fabrication and installation of the insulation in the aircraft is a labor-intensive task. Tailored, rigid particle foam parts could be a solution to speed up the installation process. The presented study investigates the feasibility of such a concept from a hygrothermal point of view. Due to the temperature difference between the cold air trapped between aircraft skin and insulation on one side and the warm cabin air on the other side, a buoyancy-induced pressure difference forms. This effect drives the warmer air through leakages in the insulation system towards the cold skin. Here, moisture contained in the air condenses on the cold surfaces, increasing the risk for uncontrolled dripping (“rain in the plane”) when it melts. Therefore, this study compares the condensate build-up of different installations of a rigid particle foam frame insulation with the classical glass fiber capstrip. Tests are hosted in the Fraunhofer Lining and Insulation Test Environment chamber. It is shown that careful installation of the particle foam frame insulation provides similar level of moisture protection as the current state of the art insulation, and that the condensate amount does not depend on the amount of airflow directly behind the sidewall. Full article
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13 pages, 3502 KiB  
Article
Development of a Novel Hybrid Thermoplastic Material and Holistic Assessment of Its Application Potential
by Christos V. Katsiropoulos, Spiros G. Pantelakis, Marco Barile and Leonardo Lecce
Aerospace 2021, 8(11), 351; https://doi.org/10.3390/aerospace8110351 - 18 Nov 2021
Cited by 3 | Viewed by 2286
Abstract
Τhe development of a novel hybrid thermoplastic prepreg material enabling the fabrication of next-generation recyclable composite aerostructures produced by affordable, automated technologies is presented in the present work. The new hybrid material is produced using automated equipment designed and developed for this reason. [...] Read more.
Τhe development of a novel hybrid thermoplastic prepreg material enabling the fabrication of next-generation recyclable composite aerostructures produced by affordable, automated technologies is presented in the present work. The new hybrid material is produced using automated equipment designed and developed for this reason. A preliminary assessment of the application of the new material is made to obtain material properties related to its processability as well as to its strength. A typical aeronautical flat skin panel has been identified and produced using an autoclave-based process in order to assess the potential of the new material for producing aircraft structural parts. Moreover, a newly developed holistic index is implemented to enable a more holistic comparison of the suitability of the materials used for the panel production. The aspects considered for the material comparison are the quality, the environmental footprint, and the cost. The results of the study pointed out that the hybrid thermoplastic material that has been developed represents a viable manufacturing option from an industrial point of view and that its implementation in structural component manufacturing leads to clear cost and environmental advantages. Full article
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Review

Jump to: Editorial, Research

24 pages, 5075 KiB  
Review
Structural Batteries for Aeronautic Applications—State of the Art, Research Gaps and Technology Development Needs
by Helmut Kühnelt, Alexander Beutl, Francesco Mastropierro, Frederic Laurin, Sebastian Willrodt, Alexander Bismarck, Michele Guida and Fulvio Romano
Aerospace 2022, 9(1), 7; https://doi.org/10.3390/aerospace9010007 - 23 Dec 2021
Cited by 23 | Viewed by 7377
Abstract
Radical innovations for all aircraft systems and subsystems are needed for realizing future carbon-neutral aircraft, with hybrid-electric aircraft due to be delivered after 2035, initially in the regional aircraft segment of the industry. Electrical energy storage is one key element here, demanding safe, [...] Read more.
Radical innovations for all aircraft systems and subsystems are needed for realizing future carbon-neutral aircraft, with hybrid-electric aircraft due to be delivered after 2035, initially in the regional aircraft segment of the industry. Electrical energy storage is one key element here, demanding safe, energy-dense, lightweight technologies. Combining load-bearing with energy storage capabilities to create multifunctional structural batteries is a promising way to minimize the detrimental impact of battery weight on the aircraft. However, despite the various concepts developed in recent years, their viability has been demonstrated mostly at the material or coupon level, leaving many open questions concerning their applicability to structural elements of a relevant size for implementation into the airframe. This review aims at providing an overview of recent approaches for structural batteries, assessing their multifunctional performance, and identifying gaps in technology development toward their introduction for commercial aeronautic applications. The main areas where substantial progress needs to be achieved are materials, for better energy storage capabilities; structural integration and aircraft design, for optimizing the mechanical-electrical performance and lifetime; aeronautically compatible manufacturing techniques; and the testing and monitoring of multifunctional structures. Finally, structural batteries will introduce novel aspects to the certification framework. Full article
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