Journal of Aeronautics and Space Technologies <p>As National Defense University Hezârfen Aeronautics and Space Technologies Institute,&nbsp;our vision is to educate innovative academic personnel with an enterprising spirited professionalism. Aiming to give superior qualifications for both national and international standards, we are striving for our academic potential to contribute scientific and technologic developments parallel to social demands and becoming a pioneer on their respective fields of studies.</p> <p>The Journal of Aeronautics and Space Technologies is published as an international refereed journal that consists of scientific and academic knowledge in January and July biannually by Hezârfen Aeronautics and Space Technologies Institute.</p> <p>The Journal of Aeronautics and Space Technologies is publishing the article without charging any fee from the author (Free of charge) and offering their readers to read/download articles freely (Open-access) without any type of fee.</p> en-US <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> <p>&nbsp;</p> (Asst.Prof.Serdar MENEKAY) (Dr.Emrah KÖKSALMIŞ) Fri, 30 Jul 2021 21:09:32 +0000 OJS 60 Unmanned Aerial Vehicle Selection Using Fuzzy Choquet Integral <p>Unmanned aerial vehicle (UAV) selection is not an easy decision as many alternatives and criteria must be evaluated at the same time. This selection decision requires the consideration of many different criteria including payload capacity, maximum speed, endurance, altitude, avionics systems, price, economic life, and maximum range. The main aim of this study is to decide the most appropriate UAV by considering these criteria. The fuzzy logic-based fuzzy Choquet integral methodology is used to select this vehicle which allows decision-makers to define references as linguistic and in interval range. A numerical example is presented to analyze the applicability of the proposed approach. The proposed approach resulted in a successful application by comparing different UAVs and the most appropriate vehicle is selected at the final stage.</p> Muhammet Enes Akpınar ##submission.copyrightStatement## Fri, 30 Jul 2021 20:58:55 +0000 Investigation of Mechanical Properties of Notched Samples Manufactured by Additive Manufacturing Method Under Different Impact Velocities <p>Fused Filament Fabrication (FFF), which is one of the additive manufacturing methods, has recently found industrial usage areas and has become frequently used. Industries using this production method can be listed as: automotive, machine manufacturing, aerospace, etc. While heat and environmental resistance are important factors for parts such as fixtures and apparatus manufactured with this method, mechanical properties are often at forefront. In many studies, the properties of the materials used in FFF under static load have been investigated by tests such as tensile, compression and bending. However, studies on mechanical properties under impact loading remained at a relatively low level. It is clear that material behavior under impact loading is important, especially for polymer materials.</p> <p>In this study, the impact resistance of notched Polylactic acid (PLA) samples produced by FFF method under different impact velocity was investigated. For this aim, a Charpy impact testing machine with low capacity (10J) was designed and manufactured, and the hammer was dropped from different heights and different velocity values were obtained. The instantaneous angle of the arm to which the hammer is attached was recorded by a gyro sensor and Arduino. Impact resistance values calculated depending on the impact speed were evaluated comparatively.</p> Mumin Tutar ##submission.copyrightStatement## Fri, 30 Jul 2021 20:59:40 +0000 Modified Grey Wolf Optimizer with Parasitism Phase <p>Grey Wolf Optimizer (GWO) is a popular and effective nature-inspired, swarm intelligence based metaheuristic optimization algorithm which imitates the hunting process of a wolf pack in the nature. It has been widely used to solve both theoretical and real life engineering optimization problems. Even though metaheuristics have many advantages such like requiring no derivative information of the problem at hand, simplicity, and flexibility, they also have some drawbacks like trapping local optima, and premature convergence. They should have a proper balance between diversification (exploration) and intensification (exploitation). In this study, inclusion of a simple operator, namely "parasitism", is proposed to improve the performance of GWO by means of exploration. Parasitism is a phase within Symbiotic Organisms Search (SOS) algorithm. The performances of 2 modified versions are compared with the original GWO, using 13 test beds. Results indicate that inclusion of parasitism phase into the original version has produced better results on the parameters of the algorithm.</p> Ali Nadi Ünal, Funda Seçkin ##submission.copyrightStatement## Fri, 30 Jul 2021 21:00:14 +0000 Wind Tunnel Tests for a Pitot-Static Probe Designed To Measure Aircraft Speed and Altitude at Subsonic Compressible and Transonic Regimes <p>A pitot-static probe to measure speed and altitude of aircrafts over a range of flight speeds from 0.5 to 0.95 Mach was designed by means of computational fluid dynamics (CFD) analyses and its tests carried out at ITU Trisonic Wind Tunnel. The goal of design studies is to achieve acceptable low error rates in both speed and altitude measurements. The purpose of the wind tunnel tests is to verify the results obtained from the CFD analyses and to determine the characteristics of the designed probe under real flow conditions. In this paper, the parameters used in the design and their effects on the measurement performance of the probe are discussed. In addition, wind tunnel testing methods applied to obtain the characteristics of the designed pitot-static probe with high accuracy are given in detail in this article.</p> Hasan Tabanlı, Kemal Bulent Yüceil ##submission.copyrightStatement## Fri, 30 Jul 2021 21:01:00 +0000 A General Framework for Teaching Software Engineering and Improving Collaboration Skills in Multidisciplinary Teams <p>International Engineering Accreditation (IEA) organizations measure, ensure and improve the quality of the engineering education in many colleges and universities worldwide. Multidisciplinary projects are required by the criteria of IEA organizations due to their contribution in students’ learning skills improvement.</p> <p>This paper presents a framework for Software Engineering Education based on the IEA criteria. So, a multidisciplinary project between computer engineers and designers is presented aiming to improve student’s understanding of software processes and increase their communication skills in multidisciplinary teams. The project includes the creation of a game application running on mobile phones. Computer engineer students form multidisciplinary teams, are assigned with distinct responsibilities, follow specific software engineering processes, participate on meetings and communicate via web-based project management tools. Their evaluation is made according to the IEA outcomes.</p> <p>As the results show, a multidisciplinary project structured according to specific IEA outcomes ensures students’ skills in software processes and give them an overall satisfaction. According to students’ surveys and overall project experience, methods and procedures for developing collaboration skills in multidisciplinary projects are necessary. The creation of a profession learning seminar improved student’s communication skills thus showing that additional methods towards this direction need to be further designed and tested.</p> Dionysis Goularas, Mert Ozkaya, Tacha Serif, Sezer Goren ##submission.copyrightStatement## Fri, 30 Jul 2021 21:01:41 +0000 Comparison of Encrypted Image Transfer Approaches That Provide Secure Video Transfer for UAV Systems <p>Today, Unmanned Aerial Vehicles (UAVs) become one of the leading technologies that are widely used for different purposes. Even though UAV systems are platform systems containing different hardware for a specific task, almost all UAV systems transmit real-time images to ground control stations (GCS). In this study it is aimed to review the methods included in the literature to ensure safe video transmission between UAV platforms and GCS and to compare their use in UAV systems by testing them on a scenario. Naive, Pure Permutation, Zigzag Permutation and Selective algorithm approaches that are among the widely used video encryption algorithms in the literature is selected as exemplary structures in this study, both because they need relatively low processing power and because they may be suitable approaches to real-time needs on mobile platforms.Within the scope of the study, a total of six performance criteria is determined and the algorithms are evaluated separately according to the performance criteria. As a result of the study, the most suitable solution for safe video transmission between UAV platforms and GCS is presented in a comparative perspective.&nbsp;he Selective Algorithm is selected among 4 methods examined as it is necessary&nbsp;to ensure the security of real-time image transfer in UAV systems as well as&nbsp;the fast communication between the UAV and GCS.</p> Ebrar Şahin, Ömer Çetin ##submission.copyrightStatement## Fri, 30 Jul 2021 21:02:14 +0000 Ozone Level Prediction with Machine Learning Algorithms <p>The ozone level in the atmosphere not only affects the quality of life of all living things and but also causes deaths. Ozone is a gas that allows it to be put into the radiation value coming from the sun rays. Therefore, when the ozone level exceeds a certain threshold, the risk situation increases. Machine learning algorithms have the ability to make inferences from these data in situations that they have not encountered before, if sufficient data is obtained about the problem to be applied. In this study, a hybrid machine learning algorithm is proposed, and ozone level estimation is aimed to prevent this before there is a risk. The proposed hybrid model results in two stages. In the first stage, clustering is made with the method of genetic algorithms and the cluster result is transmitted as an introduction to the XGBoost classifier method. To show that the proposed model is applicable, support vector machines, random forest, multi-layered neural networks and XGBoost methods, which are among the frequently used machine learning methods, have been applied to the same problem. After the 10-fold validation applied, the proposed model reached the most successful accuracy rate with 94%.</p> Atınç Yılmaz ##submission.copyrightStatement## Fri, 30 Jul 2021 21:02:36 +0000 A Review on Visual Inspection Methods for Aircraft Maintenance <p>During aircraft maintenance, the control of damages such as crack, burn, corrosion should be done precisely. Therefore, the process can take a long time. In the case of rapid control, errors cannot be detected properly. However, since the control process is usually carried out by naked eye, it is quite open to human-induced risks. In recent years, with the expansion of the application area of artificial intelligence, the use of modern techniques in aircraft maintenance and breakdown operations has been increasing in the aviation industry. In this study, deep learning-based visual inspection methods involved in aircraft maintenance and repair are surveyed.</p> Ramazan Duvar, Mustafa Böyük, Oğuzhan Urhan ##submission.copyrightStatement## Fri, 30 Jul 2021 21:03:53 +0000 Noise Reduction of Open Cavities by Passive Flow Control Methods at Transonic Speeds using OpenFOAM <p>Flow over a cavity is one of the most intriguing problems in the field of aeronautics. Even though the geometry is simple, the physics behind the cavity requires uttermost attention and detailed investigation. &nbsp;In this study,&nbsp;various novel passive flow control techniques such as reshaping the cavity aft wall in a stair-stepped configuration or combination of spoilers with reshaped cavity aft wall as a combined method are applied to cavity and effects of these techniques are investigated numerically in detail. Combined configurations of aft wall reshaping and spoiler to fore of the cavity that are proposed in the present study are novel and have a potential to contribute to the literature. Analyses are performed with Detached Eddy Simulation (DES) method three-dimensionally in transonic regime (0.85 Mach) for a Reynolds number of ~10<sup>7</sup> based on the cavity length, 0.508 m, using the open-source software OpenFOAM. Results are compared with both experimental data and each other, fundamentally in terms of Overall Average Sound Pressure Level (OASPL). Further examinations are also performed for features such as Mach number, turbulent intensity and turbulent coherent structures. It is seen that combined passive flow control methods have reduced OASPL ~10 dB. Newly proposed passive flow control methods have also reduced OASPL by ~6 dB. A high correlation between coherent turbulent structures and generated noise is observed.</p> Oğuzhan Demir, Bayram Çelik, Kürşad Melih Güleren ##submission.copyrightStatement## Fri, 30 Jul 2021 21:04:34 +0000 Comparison of Metaheuristic Algorithm Performances for Optimization of Fractional Order PID Controllers Applied to Gas Turbine Power Plant <p>Nowadays, the use of metaheuristic optimization algorithms is becoming widespread because of easy applying and be able to provide requirements in the solution of high level complex optimization problems. In this study, four different metaheuristic optimization algorithms (particle swarm optimization, artificial bee colony, gray wolf optimization, moth-flame optimization) are used for the optimization of the fractional order PID (FOPID) controller applied to the gas turbine power plant model, which is considered as the sample model, and the transient responses of the optimized systems compared according to the system output signals. The settling time, maximum overshoot percentage and rise time are used as comparison criteria, and then it is concluded that the grey wolf optimization and artificial bee colony algorithms provided superior results with respect to the other algorithms discussed. By using metaheuristic algorithms, the optimization of the fractional order PID controller applied to the gas turbine power plant model has been achieved.</p> Kunter Sercan Sezer, Nevra Bayhan ##submission.copyrightStatement## Fri, 30 Jul 2021 21:05:26 +0000 Angular Velocity Estimation for Nanosatellites Using Vector Measurements <p>In the absence of gyro sensors, the straightforward approach to estimate the angular velocity is using a dynamics-based attitude filter which can provide angular rate information together with the attitude of the satellite. However, this approach requires also the reference directions for the vector measurements. In this article, assuming that the reference directions are not known, two different algorithms for angular velocity estimation, using only the body vector measurements are given and compared. They both rely on pre-filtering the noisy data, specifically for the magnetometer measurements. The first algorithm estimates the Residual Magnetic Moment (RMM) terms along with the angular velocity vector. The second algorithm does not use the spacecraft dynamics and model the angular accelerations as a first-order Markov process. Demonstrations show the first algorithm can provide an accuracy up to 0.035 deg/s for angular velocity estimates and accurately estimate the RMM terms, whereas the second algorithm is a computationally efficient alternate that can be used flexibly at any mission phase.</p> Halil Ersin Soken ##submission.copyrightStatement## Fri, 30 Jul 2021 21:06:01 +0000 Structural Behavior Examination of Frequently Used Solid Propellant Sections Under Centrifugal Loading Using Response Surface Method <p>This research aims to examine structural responses of frequently used solid propellant sections such as tubular, star, slotted, wagon wheel, and anchor subjected to centrifugal acceleration load. Viscoelastic finite element models of the grains having different dimensions are constructed and solved in Abaqus environment using in house parametric Python scripts prepared within the content of this work. Validation of the finite element models is accomplished comparing finite element results with an analytical equation found from literature. Finally, different response surfaces are constructed in Minitab environment to determine effect of grain cross-section parameters on von Mises stress level of the propellant. Thus, the most effective cross-section parameters on von Mises stress are determined for the examined grain shapes.</p> Ceyhun Tola, Hatice Begüm Eylenoğlu ##submission.copyrightStatement## Fri, 30 Jul 2021 21:06:34 +0000 Robust Pitch Rate Control Augmentation System for an F-16 Aircraft <p>Military aircraft technologies are strategic research subjects of study. In particular, the concept of the fifth-generation fighter jet pushes the boundaries of technology. In this context, the control systems used in these aircraft are becoming more and more sophisticated. In this paper, a novel robust pitch rate control augmentation system is proposed for an F-16 aircraft. Two design objectives are determined for the design of this control system: (i) the aircraft follows the reference pitch-rate command in an agile way; (ii) ensuring the robust stability against enormous moment disturbances that may occur during the flight. An &nbsp;control approach is used in the design of this control system for both ensuring the stability and a good performance. Finally, this proposed control structure is verified with the nonlinear F-16 flight simulations. The performance of the proposed controller is compared to the classical controller approach. It is shown that the proposed controller both performs a fast pitch rate tracking and quickly suppresses the enormous pitching moment disturbance that the classical controller cannot cope. Thus, with the robust controller design, flight safety is provided in the case of adverse flight conditions.</p> Ilkay Gumusboga ##submission.copyrightStatement## Fri, 30 Jul 2021 21:07:02 +0000 Visual Target Detection and Tracking Based on Kalman Filter <p>In this study, in order to prevent collision and target tracking in autonomous aircraft, Kalman filter with appropriate solutions for target detection and tracking problems are presented. For the Kalman filter application, the motion-based tracking method that facilitates the tracking of multiple objects has been used. A background subtraction algorithm was used for the detection of moving objects while corrective actions were applied to the foreground mask to eliminate noise, and the connected pixel groups to correspond to moving objects were identified. The image used represents an image taken by a hovering drone. Although the tracked multiple targets disappeared behind the obstacle, the estimated location was determined thanks to the Kalman filter. Thanks to the fine tuning of the program codes, a successful follow-up has been achieved. The program has continued to follow the moving shadow as a part of the target.</p> Gulay Unal ##submission.copyrightStatement## Fri, 30 Jul 2021 21:07:29 +0000 Chaotic Particle Swarm Optimisation Algorithm Based Quadrotor Control <p>Unmanned aerial vehicles are currently used for civil and military purposes. To illustrate such vehicles are quadrotor aircrafts which are underactuated systems. Quadrotors have huge nonlinearities compare to conventional aerial vehicles due to not being scheme based on uncertainty environments. For this reason, Chaotic Particle Swarm Algorithm can be employed in order to overcome and regulate this issue. In this study, a nonlinear system model of the IRIS+ Quadrotor is used and the classical PID is designed by means of CPSO algorithm. The Chaotic Particle Swarm Algorithm is used in order to emerge stable reference model for robust adaptive control the experimental testbed. Additionally, the proposed algorithm is applicable for scheme-based techniques.</p> Muhammed Buğrahan Artuç, İsmail Bayezit ##submission.copyrightStatement## Fri, 30 Jul 2021 21:07:53 +0000