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    Analyzing the hydrogen supply chain for airports: Evaluating environmental impact, cost, sustainability, viability, and safety in various scenarios for implementation
    (Elsevier, 2023) Degirmenci, Hursit; Uludag, Alper; Ekici, Selcuk; Hikmet Karakoc T.
    It is a matter of great concern that the aviation industry, which has made significant contributions to the transportation sector, relies heavily on nonrenewable fossil fuels that are causing substantial pollution, leading to the industry’s unsustainability. To address this issue, the industry has shifted its focus towards sustainable aviation fuels, with hydrogen fuel showing great promise due to its clean and eco-friendly nature. However, the adoption of hydrogen as an energy carrier in aviation presents several challenges, including the lack of a supply chain comparable to that of kerosene, which is currently the primary fuel used in aviation. The supply chain for hydrogen involves various sub-sections such as production, liquefaction, transport, storage, and distribution. This study aims to analyze the hydrogen supply chains for airports and to develop scenarios for its imple mentation. The study evaluates the environmental impact, cost, sustainability, viability, and safety in different supply chain scenarios, as well as recommending a comprehensive approach to supply chain development that involves collaboration between industry, government, and academia.
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    Challenges, prospects and potential future orientation of hydrogen aviation and the airport hydrogen supply network: A state-of-art review
    (Elsevier, 2023) Degirmenci, Hursit; Uludag, Alper; Ekici, Selcuk; Karakoc, T. Hikmet
    The use of fossil fuels, which are employed to supply the energy needs of aircraft, is currently causing severe environmental concerns, placing pressure on the aviation industry and mandating specific action. Sustainable aviation fuels that would lessen the aviation industry’s environmental effects are viewed as a potential substitute for fossil fuels. Hydrogen, a clean energy carrier, is regarded as the most promising of these fuels. This paper provides a historical overview of hydrogen-powered aviation, as well as an analysis of the hydrogen supply network, which is regarded as a critical component. As part of the Sustainable Development Goals (SDGs), this study offers a future-oriented concept as well as challenges, prospects, potential future orientation and modifications that can be made to the hydrogen supply network for full decarbonization.
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    A Comparative Study between Paper and Paperless Aircraft Maintenance: A Case Study
    (MDPI, 2023) Karakılıç, Elif; Günaltılı, Enes; Ekici, Selcuk; Dalkıran, Alper; Ballı, Özgür; Karakoç, Tahir Hikmet
    The rapid growth of airlines over the last period has led to the development of the aviation industry, resulting in increased requirements for ancillary services. Nowadays, the demand for the use of paper-based documents is increasing day by day as airlines encourage passengers to use more ancillary products. One of the most important issues in the aviation industry is flight safety. The procedures and instructions required for all aviation operations are organized in accordance with the regulations and printed on paper in accordance with the demands. For this reason, since it is mandatory to keep all aircraft maintenance, repair, and operation records on printed paper and to keep them for a certain period of time, aircraft fly with almost their entire weight on paper. Considering the global hazards in the world, although the aviation sector is the least environmentally damaging of all transportation sectors, new solutions have been sought to make aviation operations less harmful to the environment, minimize errors and risks, allow for faster communication, and be safer and more sustainable. In order to meet the demands, studies on reducing the use of paper have been brought to the agenda. In this study, after a literature review, real data from a maintenance, repair, and overhaul organization are used to suggest digital conveniences that can save costs, increase productivity, save space, facilitate documentation and information sharing, keep personal information more secure, and help the environment through paperless living.
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    Conceptual design and optimization of a sustainable and environmentally friendly archetypal helicopter within the selection criteria and limitations
    (Elsevier, 2023) Gunaltili, Enes; Ekici, Selcuk; Kalkan, Abdullah; Gocmen, Faruk Esat; Kale, Utku; Yilmazoglu, Zeki; Karakoc, T. Hikmet
    The design and mission requirements of aero vehicles, which vary on a day-to-day basis, have become major study concerns in the burgeoning aviation sector. In addition to the design and mission criteria that must be met in an aero vehicle design, the designers’ primary goals are to construct original, innovative, environmentally friendly, fuel-efficient, and sustainable designs. In this study, a detailed conceptual design of a helicopter that does not need a notable runway for operation and is limited by mission and design requirements is offered. Within the scope of this research, a competitor analysis study was undertaken in accordance with the defined criteria, and design approaches were chosen based on the outcomes of competitor analysis. In addition, this research, which looks for an environmentally friendly and sustainable design, was developed with the aviation industry’s demands in mind by analyzing the International Helicopter Safety Team’s (IHST) data. As a result of the reports analyzed and considering the causes and consequences of accidents that have happened, the objective of the design research was to achieve a sustainable, ecologically friendly, and fuel-efficient design by reducing the number of accidents and damage. The planning and design processes as a result of this examination are essential as a step towards the helicopter being an original design and in the context of solution methodologies. This archetypal design aims to shed light on helicopter design studies and serve as a roadmap for future research.
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    Deep learning-based forecasting modeling of micro gas turbine performance projection: An experimental approach
    (Elsevier, 2023) Kilic, Ugur; Villareal-Valderrama, Francisco; Ayar, Murat; Ekici, Selcuk; Brooks, Luis Amezquita; Karakoc, T. Hikmet
    Performance forecasting of aeroengines is crucial for achieving better operational efficiency, ensuring safety, reducing costs, and minimizing environmental impact in the aviation industry. It enables engineers and researchers to make informed decisions, leading to advancements in technology and the overall evolution of aviation. This study is focused on the effects of flight conditions on the performance of a turbojet, which in consequence affects the environmental aspect of operation. By investigating the relationships between aeroengine efficiency and performance indicators such as thrust, shaft speed, and exhaust gas temperature (EGT), and flight characteristics expressed in terms of environmental and operational conditions, the study seeks to elucidate these connections. The article's significance lies in its successful application of Long Short-Term Memory (LSTM) networks to predict thrust, shaft speed, and EGT variations in turbojet engines under varying flight conditions. Experimental data from a turbojet test bench is processed with deep learning, specifically LSTM recurrent neural networks that are developed based on Matrix Laboratory (MATLAB). The model inputs are free stream air speed, compressor inlet pressure, combustor inlet temperature, combustor inlet pressure, turbine inlet temperature, turbine inlet pressure, nozzle inlet pressure and fuel flow, and the outputs are thrust, shaft speed and EGT. Predicted thrust closely aligns with actual thrust values, though with minor discrepancies. Shaft speed predictions exhibit a similar trend, while EGT predictions showcase a comparable pattern with slight variations. Despite the prediction errors, a thorough evaluation of median values, box plots, and probability density functions confirms that the models effectively capture available information, though discrepancies may arise from measurement inaccuracies and initial engine conditions. These results show that it is possible to accurately predict turbojet performance using LSTM recurrent neural network. This research paves the way for enhanced aeroengine performance prediction, particularly in scenarios requiring off-board or high-performance applications.
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    Editorial: VSI EGET2022
    (Elsevier, 2023) Karakoc, T. Hikmet; Yu, Zhibin; Ekici, Selcuk; Zhao, Jian
    The overarching objective of the Glasgow Climate Pact, a bold and ambitious undertaking, is to lay the groundwork for all the world’s economies, without exception, to decisively and irreversibly achieve the remarkable feat of hitting the net zero greenhouse gas emissions mark by the year 2050. The rationale behind this audacious goal is to arrest and neutralize the increasingly dire, ominous and pervasive impact of global warming on a planetary scale, and ensure that the rise in temperatures does not exceed the precarious 1.5? Celsius threshold above pre industrial levels. As such, it becomes crystal clear that it is a matter of utmost urgency that we, as a collective, wholeheartedly embrace and fervently pursue the adoption of green energy technologies, in all their multifarious and sundry forms, to enable us to inexorably advance to wards a state of civilization that leaves no carbon footprint, net or otherwise. However, this formidable challenge can only be surmounted through the vigorous and concerted efforts of the scientific and engi neering communities, who must endeavor to both invent and engineer innovative, cutting-edge low- or zero-carbon energy technologies, while also seeking to optimize and augment the efficiency and efficacy of our current energy systems, all while being mindful of the imperative to optimize cost-effectiveness in the process.
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    Fuel-saving and emission accounting: An airliner case study for green engine selection
    (Elsevier, 2023) Ekici, Selcuk; Ayar, Murat; Karakoc, T. Hikmet
    In this research, differences in the quantities of hazardous emissions induced by equipping the first composite constructed narrow body aircraft, which is commonly used in commercial aviation today, with the most common engine combinations are examined. Each engine combination that is the subject of this research is actively deployed by a number of airlines and serves the majority of passenger transportation demands. The objective is to clearly depict the variation in the quantities of emissions generated by the various engine types employed in this commonly used passenger aircraft. The instability in the amounts of emissions in various flight phases of the same aircraft, performed with various engine specifications on the same trajectory and route, is determined using EUROCONTROL's Integrated Aircraft Noise and Emissions Modelling Platform (IMPACT), which is founded on the Base of Aircraft Data, Federal Office of Civil Aviation (FOCA), and International Civil Aviation Organization's (ICAO) Helicopter and Aircraft Engine Emission Database. The research seeks to answer the following question: Considering that airlines serve many destinations throughout the year, how much fuel saving and, indirectly, emissions mitigation are achieved per sortie as a result of replacing the engines used by airlines in their existing fleets with the most environmentally friendly equivalents?
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    Performance based analysis for the Ankara-London route in terms of emissions and fuel consumption of different combinations of aircraft/engine: An IMPACT application
    (Elsevier, 2023) Ekici, Selcuk; Ayar, Murat; Kilic, Ugur; Karakoc, T. Hikmet
    This study analyzes two types of aircraft offered to the industry by two different manufacturers on an identical route and trajectory for commercial aviation and the noxious emissions resulting from equipping these aircraft with the most frequently used engine combinations today. The research covers the most recent Base of Aircraft Data (BADA v4.2_1), the Aircraft Noise and Performance (ANP v2.3), and the ICAO Engine Emission Database (254-ICAO EDDB25/FOCA) based integrated aircraft noise and emissions modelling platform (IMPACT) devel oped by EUROCONTROL. The striking findings in fuel consumption and emissions of four different scenarios during identical flight operations are detailed. The research presents the application of a systematic aircraft engine pair decision mechanism for investigators, scientists, airline operators, policy analysts and legislators, in accordance with a comprehensive computer simulation method that consistently acknowledges the fuel consumption and emissions analysis of aircraft-engine parings.
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    Promising fuels and green energy technologies for aviation
    (Taylor and Francis Ltd., 2022) Karakoc, T. Hikmet; Colpan, Can Ozgur; Ekici, Selcuk; Yetik, Ozge
    Promising fuels and green energy technologies for aviation
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    Unleashing the Potential of Morphing Wings: A Novel Cost Effective Morphing Method for UAV Surfaces, Rear Spar Articulated Wing Camber
    (MDPI, 2023) Ozbek, Emre; Ekici, Selcuk; Karakoc, T. Hikmet
    The implementation of morphing wing applications in aircraft design has sparked signifi cant interest as it enables the dimensional properties of the aircraft to be modified during flight. By allowing manipulation of the 2D and 3D parameters on the aircraft’s wings, tail surfaces, or fuselage, a variety of possibilities have arisen. Two primary schools of thought have emerged in the field of morphing wing applications: the mechanisms school and the smart surfaces approach that uses shape-memory materials and smart actuators. Among the research in this field, the Fishbone Active Camber (FishBAC) approach has emerged as a promising avenue for controlling the deflection of the wing’s trailing edge. This study revisits previous research on morphing wings and the FishBAC concept, evaluates the current state of the field, and presents an original design process flow that includes the design of a unique and innovative UAV called the Stingray within the scope of the study. A novel morphing concept developed for the Stingray UAV, Rear Spar Articulated Wing Camber (RSAWC), employs a fishbone-like morphing wing rib design with rear spar articulation in a cost-effective manner. The design process and flight tests of the RSAWC are presented and directly compared with a conventional wing. Results are evaluated based on performance, weight, cost, and complexity. Semi-empirical data from the flight testing of the concept resulted in approximately a 19% flight endurance increment. The study also presents future directions of research on the RSAWC concept to guide the researchers.