Journal of Aeronautics and Space Technologies

Influence of Time Intervals: Comparative Analysis of Short-Arc Orbit Determination for GEO Satellites Using AER and RNG Methods

Ümit Cezmi Yılmaz — 2024-07-31

Short arc orbit determination for GEO satellites is useful when there are gaps or incomplete data due to limited time or other factors. Full cycle orbit determination requires continuous data over the entire orbit cycle, which may not always be available. This research assesses the accuracy of short arc orbit determination for GEO satellites for various time intervals ranging from 6-hour- to 42-hour intervals using two data collecting techniques: azimuth elevation range (AER) and range-to-range (RNG). Iterative Least-Squares Estimation, a numerically integrated method, is then used to determine the orbit, by either calculating new bias values or pre-existing bias values. The results show that average root mean square error (RMSE) values are 0.792 km and 0.160 km for AER and RNG type observation data, respectively, using pre-existing bias values. On the other hand, using new bias calculation, the average RMSE values are 36.480 km and 6.254 km for AER and RNG. The findings indicate that the RNG method provides superior accuracy in determining the orbit for both satellites. The study recommends the use of pre-existing bias values over calculating new ones. Short arc orbit determination can provide a reasonable estimate of the satellite's orbit when a limited amount of data is available due to various reasons and can also be used to quickly assess and correct any deviations or errors in the satellite's orbit, improving overall accuracy and reliability.

Depth Analysis in Deep Learning-Based Automatic Modulation Classification

Osman Kaya — 2024-07-31

Automatic Modulation Classification (AMC) is the process of determining the modulation type of a signal received by a communication system. Deep learning, a machine learning technique, has recently garnered significant attention due to its outstanding ability to classify intricate data structures. This study delves into the critical role of automatic modulation classification processes in both civil and military applications, utilizing Convolutional Neural Networks (CNN) as a deep learning approach. In this study, unlike other studies, the effect of changing the depth level of the network on the accuracy level was investigated.

Design and Performance Analysis of 2x2 and 3×3 Phased Array Patch Antennas in C Band

Abdifatah Abdulkadir Ahmed — 2024-07-31

The design and analysis of 2x2 and 3x3 phased array patched antennas operating at C-band frequencies are presented in this work. The antenna array is made up of rows and columns of patch antenna elements connected together by a shared feed network. The goal is to develop a high-gain, low-side lobe level antenna system with beam steering capabilities. To allow beamforming, the antennas are constructed in 2x2 and 3x3 arrays. Rogers RT5880 is the substrate utilized, having a dielectric constant of 2.2 and a thickness of 1.6 mm. The performance of the antenna was evaluated using computer simulation technology (CST) microwave studio software. The results showed that the 2x2 arrangement had a directivity of 12.38 dBi while the 3x3 design had a directivity of 15.30 dBi. Other elements that benefited from the simulation results included the reflected coefficient, beam gain, voltage standing wave ratio, bandwidth, efficiency, E-field, and H-field.

Numerical Predictions of Tip Shape Effect on Helicopter Rotor Noise in Forward Flight

Tuğrul Teoman Öztürk — 2024-07-31

The effect of helicopter rotor blade tip shape on overall aircraft noise level is analyzed, in forward flight conditions. The infamous HART-II experimental data is used as a base for validations. Commercially available CFD software Ansys/Fluent is used to model the flow field over rotor-body interaction with moving-deforming meshes. The blades are modelled individually to match the actual physical blade geometry and blade movement. The acoustics calculations are performed via FW-H modelling of the software. HART-II blade has a rectangular blade tip planform. Four different tip shapes are modeled and analyzed in addition to the original blade planform. Baseline case of HART-II experiment is used for the predictive calculations. The predictions show that the least sound pressure level obtained by %10 c notched tip shape having 10-degree anhedral angle with 2,23 dB(A) difference amongst other four tip shapes.

Thermal Barrier Coating Materials Review

Adalat Samadov — 2024-07-31

The priority technological direction of thermal protection of hot section components, basically turbine parts is the development of thermal barrier coatings (TBCs) in order to improve the operational performance of aero gas turbine engines (GTEs). The application of this coating, which can lower the surface temperature of the substrate material and have high oxidation resistance, was of great importance. The focus of this paper is on choosing TBCs with lower conductivity and longer life than coatings used in industry today and on the study of the effect of TBCs with low thermal conductivity on the longevity and performance of the GTE. Although this type of coating consists of multilayers, here only an overview of the coating materials used in their top layer is given. This review is based essentially on the thermal and mechanical properties of these materials. Although there are many oxide materials that meet the specified requirements and are considered suitable for use as a ceramic top layer in the TBC system, the most promising one was selected. Compared to traditional TBC systems, it is a pyrochlore type oxide with very low thermal conductivity, high thermal stability, and some other advantages - Lanthanum zirconate (La2Zr2O7, LZ).

Numerical Study of 2D Curved Shock Wave Turbulent Boundary Layer Interaction

Vishal Umapati Choudhari — 2024-07-31

The shock wave boundary layer interaction (SWBLI) due to curved shock is studied prominently, as most military aircrafts and missiles undergo strong SWTBLI due to its curved or blunt shape. These interactions effect the performance of vehicles at supersonic flow regime. The present numerical study investigates, interaction between a shock wave and turbulent boundary layer (SWTBLI) for cylindrical shock generators at freestream Mach number 3. The diameter (D) of cylindrical shock generator is varied to determine the effect of strength of shock on boundary layer and effect on impinging location from leading edge of flat plate, which depends upon the position of cylindrical shock generator. Two dimensional numerical simulations are carried out on mentioned model using commercially available CFD solver that employs k-omega SST turbulence model. Computational results show a good agreement qualitatively in terms of separation location and separation bubble length and quantitatively predicts the surface pressure, accurately as compared to the experiments conducted by literature.

A Study and Future Challenges in 6G Networks: Aeronautical Network, AI and Blockchain

Muhammet Ali Karabulut — 2024-07-31

This study addresses aeronautical networks, artificial intelligence (AI) and blockchain technologies that will shape the future development of 6G networks and the challenges that the integration of these technologies may face. While aeronautical networks offer wide coverage areas and uninterrupted communications, AI is revolutionizing network management and service personalization. Blockchain, on the other hand, provides security and transparency, allowing the protection of user data and the implementation of smart contracts. This integration enables the development of new services and applications while increasing the flexibility and reliability of 6G. The study highlights that the development and implementation of 6G networks requires a multifaceted and interdisciplinary research effort. Topics such as aeronautical communication, development of AI algorithms, blockchain scalability and energy efficiency should be the focus of future research. Additionally, socio-economic factors such as reducing the digital divide, legal and regulatory compliance, and user-centered design should also be taken into account. Serving as a starting point for future researchers, this study is an important step that will determine the success of 6G and shape the communication networks of the future.

The Examination of Factors Affecting Pilot Motivation with Structural Equation Modeling

Meltem Aslantaş — 2024-07-31

The primary responsibility of a pilot is to ensure aircraft control and security during the entire flight. Considering the vital nature of the job, pilots are expected to possess strong motivation, which is an important characteristic. Pilot motivation can be influenced by factors including concentration, lifestyle activities, communication, external triggers, stress, leadership, job satisfaction, and burnout. This study aims to examine the factors that influence pilot motivation. The study utilized structural equation modeling to analyze causal relationships within a theoretical framework and assess its statistical validity. In this context, submitted hypotheses explore the causal links influencing pilot motivation and the indicators that represent these characteristics. An online survey was done with a group of 256 civilian and military pilots. The survey findings were imported into SmartPLS software for analysis of the factors. The research results determined the most and least important factors causing the diversity in pilot motivation.

Path Tracking for Agricultural Spraying UAVs: A Pure Pursuit Control Approach

Erdem Arslan — 2024-07-31

This paper presents the implementation of the Pure Pursuit control algorithm for path tracking on an agricultural pesticide spraying drone. Precise path tracking ensures accurate pesticide coverage, maximizing crop yield and minimizing environmental impact. Conventional position control architectures used by most agricultural drones can lead to inconsistent pesticide distribution due to variability in drone speed. Position control also causes deceleration and acceleration at corners, resulting in over-spraying in these areas. This lack of uniform spray distribution challenges efficient and sustainable agriculture. The Pure Pursuit algorithm is favored for its simplicity and effectiveness in autonomous navigation. The software architecture, including the flight control stack and ROS2-based PX4 simulation architecture, demonstrates the drone’s accurate trajectory following capabilities. Simulation tests evaluated the path tracking accuracy and overall performance of the system. Comparative results show the Pure Pursuit controller’s superiority over standard position controllers in terms of accuracy, robustness, and adaptability. Additionally, this paper introduces an innovative Coverage Path Planning (CPP) strategy based on grid decomposition. Integrated with the Pure Pursuit control mechanism, this CPP strategy ensures precise path tracking and maximizes coverage uniformity, further enhancing the effectiveness and sustainability of agricultural spraying operations.

Forecast Analysis of Renewable Solar Energy Production Using Meteorological Data with Machine Learning Methods

Naciye Macit Sezikli — 2024-07-31

Solar energy power plants play a significant role in meeting the demand for sustainable and clean energy. However, variable weather conditions, seasonal effects, and similar factors can result in the need for energy overproduction to be stored or lead to costs associated with energy deficiency. These situations can result in inefficiencies in solar energy production. The objective of this study is to predict energy production, increase efficiency, and develop more sustainable energy strategies by using machine learning methods with data obtained from meteorological and solar energy panels. This study aims to assess the results achieved by existing models and compare their successes. The Random Forest algorithm, which achieved the highest R2 score, also obtained significantly lower values for MSE, RMSE, and MAE. This indicates that the Random Forest algorithm performs the best among the algorithms used in this study. This ranking of success is followed by Decision Trees and K-Nearest neighbors.

The History of Guided Bombs, Guidance Kits, Wing Kits, and Wing Deployment Mechanisms

Asaf Sayıl — 2024-07-31

The obligation of developed countries to achieve technological superiority for citizen security prompts significant defense budget allocations covering personnel, procurement, operations, maintenance, equipment, infrastructure, and research & development (R&D). Particularly, the R&D expenditures should not be considered a waste, since the money spent on R&D could return as battle superiority to alter the course of conflicts. Accordingly, the aim of this review paper is to provide knowledge on guided bombs, guidance kits, wing kits, and wing deployment mechanisms. The historical developments in the field were outlined, and the emergence of guided bombs and guidance kits were described chronologically with highlighting their strategic importance in previous conflicts. Also, a comparative analysis of the strengths and weaknesses of different guidance kits was presented. Besides, custom-made wing kits and wing opening systems were shown with relevant patents. Moreover, the critical role of wing kits in future conflicts, and the importance of continued research in this direction was emphasized. Finally, the current situation in the field was described with on-going challenges and possible solution proposals with an intention of serving as a guide for future studies.