Journal of Aeronautics and Space Technologies <p><iframe src="" width="100%" height="180" frameborder="0" marginwidth="0" marginheight="0" scrolling="no"></iframe></p> National Defence University Turkish Air Force Academy en-US Journal of Aeronautics and Space Technologies 1304-0448 <p>The manuscript with title and authors is being submitted for publication in Journal of Aeronautics and Space Technologies. This article or a major portion of it was not published, not accepted and not submitted for publication elsewhere. If accepted for publication, I hereby grant the unlimited and all copyright privileges to Journal of Aeronautics and Space Technologies.<br><br>I declare that I am the responsible writer on behalf of all authors.&nbsp;</p> An Open-Source Aerodynamic Shape Optimization Application for an Unmanned Aerial Vehicle (UAV) Propeller <table width="605"> <tbody> <tr> <td width="382"> <p>The unmanned aerial vehicles (UAV) become more popular and functional for today’s needs in comparison to the conventional aircrafts for military, agriculture, private purposes. Generally, these vehicles are using propeller based propulsion systems. Thus, aerodynamic shape optimization is a vital process to improve their performance. Accordingly, in the present study, a Computational Fluid Dynamics (CFD) based open-source shape optimization framework (combined use of CFD solver, Optimization solver, Free-Form Deformation (FFD) tool and Mesh Generator utility) is designed to optimize the shape of a generic UAV propeller. As a result, the open-source shape optimization framework here woks quite efficiently and the Figure of Merit (FM) of the propeller has been improved around 50 %.</p> </td> </tr> </tbody> </table> Şahin Yiğit Saleh Abuhanieh Barış Biçer Copyright (c) 2022 Journal of Aeronautics and Space Technologies 2022-07-29 2022-07-29 15 2 1 12 Sun-Direction Estimation Under the Effect of Lunar Albedo <p>Spacecraft or the instruments are directed to certain directions or points in order to successfully complete their mission. Solar sensors are commonly used as they are capable of being used in planetary or interplanetary space missions in the solar system. Mostly, these instrument sense not only the radiation from the sun but also the albedo of any nearby object. These measurements are known to cause erroneous outputs in the attitude and control system when used without considering the albedo model. In this study, the effect of the lunar albedo on the sun sensor and sun direction estimation is evaluated under different simulation conditions.</p> Demet Çilden Güler Copyright (c) 2022 Journal of Aeronautics and Space Technologies 2022-07-29 2022-07-29 15 2 13 27 Sonic Boom Prediction Code Development and Sonic Boom Predictions via Open Source CFD Software <p style="margin-bottom: 0in; line-height: 100%;" align="justify"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;"><span lang="en-US"><em>In the present work a sonic boom prediction code which numerically solves the Augmented Burgers equation using the operator-splitting approach was developed. The developed code was tested using the near-field pressure data for the “NASA Concept 25D with Flow Through Nacelle (C25D)” and was validated by comparison with two well-known codes, namely sBoom and bBoom. A mid-solver approach, which utilizes the open source CFD software OpenFOAM® and a “Mach-cone aligned” structured mesh excluding the airplane geometry, was applied to extrapolate the nearfield pressure data to mid-field. The near-field effects were propagated to mid-field by solving the Euler equations. The Mach-cone aligned mesh used in the solutions were constructed using the open source mesh generation software Gmsh in an automated manner where the user specifies the radii of the inner and outer surfaces, mesh spacing along streamwise and circumferential directions and flow Mach number. The tests conducted using the near-field data obtained from an inviscid flow solution for the C25D geometry by the open source CFD software SU</em></span></span></span><sup><span style="font-family: Times New Roman, serif;"><span style="font-size: small;"><span lang="en-US"><em>2</em></span></span></span></sup><span style="font-family: Times New Roman, serif;"><span style="font-size: small;"><span lang="en-US"><em> showed that this mid-solver approach used can successfully propagate near-field data to mid-field regions.</em></span></span></span></p> Emre Alpman Levent A. Kavurmacıoğlu Seher Eken Harun İnci Zeliha Çamur Barış Biçer Copyright (c) 2022 Journal of Aeronautics and Space Technologies 2022-07-29 2022-07-29 15 2 28 53 A Finite Volume Based LES Solver for Turbulent Flows <p>This work presents a new large-eddy simulation (LES) solver, <strong><em>lestr3d</em></strong>, developed to study practical turbulent flow problems. <strong><em>lestr3d</em></strong> solves the compressible LES equations on unstructured grids using the finite volume method and second-order discretization schemes. The compressible Smagorinsky, wall-adapting local-eddy (WALE) viscosity, and k-equation models are available as sub-grid scale models. Efficient parallelization is accomplished using the METIS software and Message-Passing Interface libraries. <strong><em>lestr3d</em></strong> is shown to be scalable on a high-performance computing platform up to &nbsp;cores. The validation and verification analysis of <strong><em>lestr3d</em></strong> is performed on the lid-driven cavity flow problem. The results show excellent agreement with available direct numerical simulation and experimental data for the cases of k-equation and WALE with low- and high-resolution grids respectively. Then, the flow over the T106 turbine blade is studied to showcase the capabilities of <strong><em>lestr3d</em></strong>. It is demonstrated that <strong><em>lestr3d</em></strong> is capable of performing simulations on complex geometries and reliably capture spatio-temporal evolution as well as the statistics of the flow. Overall, <strong><em>lestr3d</em></strong> is demonstrated to be a valuable long-term investment for studying complex turbulent flow problems.</p> Sarp Er Doğukan Tuğberk Karahan Ayşe Gül Güngör Copyright (c) 2022 Journal of Aeronautics and Space Technologies 2022-07-29 2022-07-29 15 2 54 73 Fault Tolerant Attitude Estimation for a Nanosatellite Using Adaptive Kalman Filter with Single Scaling Factor <p>In this study an integrated adaptive TRIAD/Extended Kalman Filter (EKF) attitude estimation algorithm is presented, in which the TRIAD and an adaptive EKF are combined to estimate the attitude of a nanosatellite. The quaternion set produced by the TRIAD is provided as input to the adaptive EKF. Adaptive EKF estimates the final quaternion set and using a Single Scaling Factor (SSF), it readjusts the measurement noise covariance matrix in case of a sensor fault. The performance of the presented algorithm is tested against two different fault types as noise increment and continuous bias in attitude sensors. As a result of simulations, it is seen that although the performance of the conventional EKF reduces significantly in case of sensor faults, adaptive EKF continues to give reliable attitude estimations.</p> Hasan Kınataş Cengiz Hacızade Copyright (c) 2022 Journal of Aeronautics and Space Technologies 2022-07-29 2022-07-29 15 2 74 93 Deep Reinforcement Learning-Based Cooperative Survivability Maximization for a UAV Fleet on an Air-to-Ground Mission <p>This study focuses on the cooperative strategy development of a UAV team that operates in a hostile environment in which the radar and weapon systems try to track and eliminate them. To simulate the hostile defense system, we present Markov models that generate the detecting and tracking probabilities of a radar system, and calculate the multiple-shot survivability of air vehicles that fly within the hostile environment. A cooperative strategy development procedure is presented based on proximal policy optimization algorithm, which is a deep reinforcement learning method. It is shown that the UAV team can develop cooperative strategies by exploiting enemy’s weakness to maximize team survivability in an air-to-ground mission after training with the proposed reinforcement learning scheme.</p> Barış Başpınar Copyright (c) 2022 Journal of Aeronautics and Space Technologies 2022-07-29 2022-07-29 15 2 94 107 Data Collection from Wireless Sensor Networks: OpenMP Application on the Solution of Traveling Salesman Problem with Parallel Genetic Algorithm and Ant Colony Algorithm <p>Parallelization of algorithms can reduce time in many cases while using multiple cores at the same time. Although Algorithms such as Genetic Algorithm (GA) and Ant Colony (AC) are widely used optimization algorithms to solve the nonlinear problems it is usually time consuming. This study aims to solve a well-known NP-Hard problem, The Travelling Salesman Problem (TSP), by using both parallel and serial GA and AC. As an application, the data collected from the wireless sensors networks (WSNs) were used and the performance values of the running algorithms were compared. Reducing the travelling time in WSNs avoids losses in energy consumption caused by multi-tab transmission, but causes a long delay. Additionally, application was made with Open Multi-Processing (OpenMP) and its performance was compared with serial programming. According to the findings while both methods reduces the time in half when they run parallel, the performance of GA is much superior than AC.</p> Reşat Buğra Erkartal Ömer Çetin Atınç Yılmaz Copyright (c) 2022 Journal of Aeronautics and Space Technologies 2022-07-29 2022-07-29 15 2 108 124 Spaceport Site Selection of Türkiye Based on Three-Dimensional Uncertain Linguistic Variables <p>Since the inception of space technologies based on military programs, the process that has evolved with the engagement of civilian firms has enabled the use of these technologies in various fields. On the other hand, current trend emphasizes the importance of making these technologies accessible and inexpensive. Both state and private authorities focus on developing current technology at low cost and high success rate. Excluding technical requirements, extensive research indicate that location affects the cost and success of activities. This study suggests a hybrid decision-making model to determine the location of spaceport, which Turkey has identified as primary goal of its space program. Since space technologies are a new subject in Turkey, expert judgments include uncertainty. Fuzzy set theory is an efficient tool to overcome an uncertain environment. Hence, an approach based on spherical fuzzy AHP (Analytical Hierarchy Process) and VIKOR (VlseKriterijumska Optimizacija I Kompromisno Resenje) methods has been proposed. By a comprehensive literature review, 20 criteria and five alternative locations have been determined and evaluated. The results indicate that the most important criteria are technical requirements, cost &amp; economy, and infrastructure, respectively. Based on these criteria, the best alternative location has been identified as Somalia for Turkey spaceport site.&nbsp;</p> Melike İlhan Fatma Kutlu Gündoğdu Copyright (c) 2022 Journal of Aeronautics and Space Technologies 2022-07-29 2022-07-29 15 2 125 142