Journal of Aeronautics and Space Technologies
http://jast.hho.edu.tr/JAST/index.php/JAST
<p>Main objective of the Hezârfen Aeronautics and Space Technologies Institute is to contribute bringing up human power that is appropriate for the needs of developing science and technology, developing international knowledge, sophisticated, using scientific knowledge creatively and having secular and democratic values in addition to respecting nation benefit.</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 authors cannot make any payment for the papers published in the journal. Papers published in the journal are open access without being a member of the journal.</p>Milli Savunma Üniversitesi, Hezârfen Havacılık ve Uzay Teknolojileri Enstitüsüen-USJournal of Aeronautics and Space Technologies1304-0448<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. </p> <p> </p>Aircraft Selection Using Linear Physical Programming
http://jast.hho.edu.tr/JAST/index.php/JAST/article/view/358
<p><em>Selection of the most appropriate aircraft is an important decision affecting the profitability of an airline. This decision requires the consideration of many different criteria including seat capacity, fuel consumption and range. Hence, researchers developed various multi criteria aircraft evaluation approaches using different multi criteria decision making techniques. The major drawback of those approaches is the assignment of physically meaningless and subjective weights to evaluation criteria. The multi criteria aircraft evaluation approach presented in this study is based on linear physical programming method which eliminates the subjective weight assignment process. A numerical example is presented in order to illustrate the applicability of the proposed approach.</em></p>Mehmet Ali Ilgın
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2019-07-122019-07-12122121128A New Method in Stochastic Multi-Criteria Decision Making: SWARA-SMAA-2 and an Application
http://jast.hho.edu.tr/JAST/index.php/JAST/article/view/367
<p>The Stochastic Multiobjective Acceptability Analysis (SMAA) is a multi-criteria decision-making (MCDM) method that is preferred when there is a lack of information on selection criteria, no definite judgment on information, no credibility of the information on the criterion, or where no preferences are desired. The Step-Wise Weight Assessment Ratio Analysis (SWARA) method has emerged as a method based on the method of evaluating the weight ratios of the criteria, which is simple and rapid processes according to the known and widely known methods of MCDM. In this study SWARA-SMAA-2 method is proposed which integrates SWARA and SMAA methods. The aim of the study is to design an independent decision-making process and to make use of it by reducing the influence of uncertain and inconsistent data by integrating it with the SMAA method through the importance weights of the evaluators of decision-making field experts. The proposed method was first applied to the drug benefit risk analysis problem in the literature, and the results obtained were compared with other studies on this problem. The results of the evaluations showed that the SWARA-SMAA-2 method gave more reliable and consistent results than the other methods.</p>Korel İnanç DurmazCevriye Gencer
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2019-07-122019-07-12122129135Methodology and Realization of a Heat Pipe Performance Test in a Thermal Vacuum Chamber
http://jast.hho.edu.tr/JAST/index.php/JAST/article/view/357
<p><em>In this study, a newly developed test set-up installed in a thermal vacuum chamber and the thermal performance test performed with this set-up is described. Evaporator is simulated by using mounted resistive heaters on it whereas two black painted aluminum plates in contact with the condenser are used to remove heat from heat pipe. Thanks to the vacuum level obtained in the chamber, the convection heat transfer is eliminated; so, the heat loss from heat pipe can be neglected while calculating the maximum heat transport capacity of the heat pipe. When the proposed test methodology is applied and the measured test parameters are used, maximum heat transport capacity and effective thermal conductivity of a heat pipe can be calculated with relatively small uncertainties. Therefore, the proposed test-up and test methodology is demonstrated to be an efficient tool for the determination of heat pipe thermal parameters</em>.</p>Cem ÖmürOsman Furkan Muratoğluİlhami Horuz
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2019-07-122019-07-12122137144Peridynamics for the Solution of the Steady State Heat Conduction Problem in Plates with Insulated Cracks
http://jast.hho.edu.tr/JAST/index.php/JAST/article/view/372
<p><em>This paper presents the steady-state heat conduction analysis in plates with insulated cracks using peridynamic differential operator (PDDO).</em> <em>The PDDO converts the local differentiation to nonlocal integration. Since the PDDO permits differentiation through integration, the equilibrium equations remain valid in the presence of discontinuities such as cracks.</em> <em>The governing equations of the steady state heat equation and boundary conditions were solved by employing the PDDO. The robustness of the PDDO was assessed by considering a plate without cracks under different boundary conditions. The influence of the insulated cracks on the temperature and heat flux distributions was investigated. It was observed that heat flux concentrations developed in the vicinity of the crack tips.</em></p>Mehmet Dördüncü
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2019-07-122019-07-12122145155Use of Artificial Neural Network in Rotorcraft Cooling System
http://jast.hho.edu.tr/JAST/index.php/JAST/article/view/373
<p>In this study, an Artificial Neural Network (ANN) is used to determine the surface temperatures of the avionics equipment located in an avionics bay of a rotorcraft. The bay is cooled via a system of a fan that supplies ambient air to the interior of the bay and an exhaust. A Feedforward Multi-Layer ANN is used with the input parameters of the fan and exhaust locations and the air mass flow rate of the fan. For training of the network, the results obtained by a large number of Computational Fluid Dynamics (CFD) analyses are used. An analysis on the accuracy of the ANN algorithm through the use of different ANN architectures revealed that an ANN with fifteen neurons in the hidden layer provides the best accuracy among the considered options. The size of the training data is increased progressively and its effect on the prediction accuracy of the ANN algorithm is also observed. The regression capability of the ANN is later compared with a response surface built by a commonly used full quadratic linear model. The comparison shows that the ANN predicts the avionics surface temperatures with much better accuracy.</p>Altuğ AkınHarika S. Kahveci
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2019-07-122019-07-12122157170The LRE Design System Using a New Thermo-Gas-Dynamic Calculation Method
http://jast.hho.edu.tr/JAST/index.php/JAST/article/view/378
<p>As is well known, the energy specifications of a liquid rocket engine (LRE) determine the structural scheme, optimal geometric, mass, thrust, flight specifications and the efficiency of the rocket. Therefore, in the calculation of the LRE energy characteristics special attention is paid to thermochemical modeling of processes and the thermodynamic design of the engine chamber. Analysis of researches show that the incorrect account of the nature of chemical reactions along the length of the LRE chamber lead to errors in the assessment of the specific impulse and the formation of the engine geometry. Consequently, the problem of correctly simulating of the flow parameters distribution over the chamber volume and taking them into account for nozzle profiling arises. With known length (L=x<sub>max</sub>) and diameters of the LRE chamber main sections is possible to form the distribution of the number of moles of components, heat capacity and isentropic index (N=f(x), c=g(x) and γ=h(x)) of the gas mixture. Thus, has been developed a new system for the LRE design, which is based on the thermodynamic calculation equations, the method of characteristics and the sigmoidal function of the flow velocity distribution. This system provides optimum geometry forming of the chamber and improving of the LRE energy parameters at the preliminary design stage</p>Parviz Shahmurad Abdullayev
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2019-07-122019-07-12122171183Aircraft Trim Analysis by Particle Swarm Optimization
http://jast.hho.edu.tr/JAST/index.php/JAST/article/view/381
<p>In this work, a detailed nonlinear model for the full dynamics of the F-16 aircraft is first developed and coded in MATLAB. This model includes the gravity model, variable atmospheric parameters, tabular aerodynamic functions, propulsion model, nonlinear control surface actuation models, and six degrees of freedom equations of motion. A numerical tool for computing all possible trim values, using the aforementioned model, is then developed. This tool can calculate the trim values at different operating points. In the developed algorithms, particle swarm optimization (PSO) method, which is a meta-heuristic method with a high convergence rate over a continuous search space, is used. Simulations around the calculated trim values are then made using the developed model. Simulation results confirm that the PSO based trim algorithm can find all the trim values with a high accuracy.</p>İlkay GümüşboğaAltuğ İftar
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2019-07-122019-07-12122185196Effect of Ambient Temperature Variations on the Direct Operating Cost of a Domestic Flight
http://jast.hho.edu.tr/JAST/index.php/JAST/article/view/380
<p>This paper analyzes the direct effect of variable ambient temperature during the cruising phase and its effects on the strategies to reduce airlines direct operating costs. Fuel and time efficiency have become an increasingly important factor in the aviation industry. The fuel is one of the largest parts of airlines operating expenses and time is a parameter affecting direct operating cost items such as flight crew salaries, air traffic en-route charges, and maintenance, etc. A comprehensive aircraft performance model is developed to estimate the changes in fuel consumption and flight time by an Airbus 320 ceo due to daily temperature variations. The seasonal change of the tropopause height is taken into the account in the atmosphere model. Cost index is kept as constant in the analyses. A domestic flight between Istanbul and Hakkari is used as a sample to predict changes in the direct cost of flight at day and night, in the summer and the winter seasons. The flight time is noticed to be changing significantly with respect to temperature variations.</p>Muhaned GilaniDurmuş Sinan Körpe
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2019-07-122019-07-12122197207