Asrel Aerospace Research Letters Archive

Traditional materials are being replaced by advanced technology materials. Especially in the defense industry, aerospace and aviation, armored vehicles and automobile sector, especially in the military field, researches to increase ballistic and impact resistance and the detection of damage to the material and the optimization of new designs are focused on. Composite materials are also used in secondary structural parts of the aircraft, which are considered to be able to continue their flight partially in case of damage. A comprehensive study of the deformations that occur in the material as a result of impact is important as a contribution to the literature and as a reference for aviation maintenance personnel. In high-tech sectors, especially in the aerospace industry, composite materials with aluminum layers are preferred for payload weight compared to conventional materials. Aluminum-containing composites and aluminum-containing materials, due to their high strength to weight ratio, are vital in many sectors where payload weight is important, especially in the aerospace industry. Rubber-blend PU polymer was cured in a customized mold together with 1050 Al sheets to create the layered composite. The polymer layer was strengthened using different rows of Al wire screen. A novel approach to fabricate a reinforced composite panel in one spot was introduced. A specifically made drop weight apparatus was used to conduct a low velocity impact test. Drop weight tests were carried out at five distinct energy levels (40J, 60J, 80J, 100J and 120J) to examine the impact behavior of the specimens. Force-time histories were saved for each event. The "energy-time" and "force-displacement" variations were also obtained by kinematic analysis performed in accordance with ASTM D7136/D7136M-12 standard. No puncture occurred in any specimen. Since the specimens were layered, penetration was observed only in the top layer. In addition, the peak forces, the absorbed energy and the impact tip’s indentation are also presented. Damage to the layered composite structures after impact was investigated. No significant effect of Al sieve reinforcement in the polymer layer was observed on the low velocity impact response, except for the tests at 120 J.

In this study, the pitch angle of an aircraft is controlled using 4 different methods found in the literature. The linearized longitudinal equations of motion of the aircraft selected to be controlled in this study were obtained from the sources in the literature and the control application was made using the transfer function obtained with certain assumptions. The methods designated were used to calculate the coefficients of the PID controller and the calculations and modeling were done through MATLAB/Simulink. The methods used in the study are mainly as follows: Ziegler-Nichols, Modified Ziegler-Nichols, Tyreus-Luyben, and Astrom and Hagglund. The study aims to determine the best-performing method among these 4 methods for controlling the pitch angle of the aircraft. Comparisons were made on the graphs and tables obtained for the study and the best-performing method was determined. In this study, the pitch angle of an aircraft is controlled using 4 different methods found in the literature. The linearized longitudinal equations of motion of the aircraft selected to be controlled in this study were obtained from the sources in the literature and the control application was made using the transfer function obtained with certain assumptions. The methods designated were used to calculate the coefficients of the PID controller and the calculations and modeling were done through MATLAB/Simulink. The methods used in the study are mainly as follows: Ziegler-Nichols, Modified Ziegler-Nichols, Tyreus-Luyben, and Astrom and Hagglund. The study aims to determine the best-performing method among these 4 methods for controlling the pitch angle of the aircraft. Comparisons were made on the graphs and tables obtained for the study and the best-performing method was determined.

In this study, computational fluid dynamics (CFD) and thermodynamic analyses of the radial compressor whell, one of the key components of the small-scale micro turbojet engine used for propulsion in UAV’s, were conducted. The micro turbojet engine was analyzed under sea level conditions (101.325 Pa, 288.15 K). The compressor models were designed with 12 full blades, and the blade thickness for the compressor models was set at 1.3 mm. CFD analyses were carried out at three different operating speeds, namely 45.500, 55.500 and 65.500 rpm, with the same mass flow rates (1 kg/s) and pressure ratios (4.8). The energy efficiencies of these models were determined, followed by traditional exergy analyses, resulting in exergy efficiencies of 79.25%, 86.02% and 81.70% respectively. In this study, computational fluid dynamics (CFD) and thermodynamic analyses of the radial compressor blade, one of the key components of the small-scale micro turbojet engine used for propulsion in UAV’s, were conducted. The micro turbojet engine was analyzed under sea level conditions (101.325 Pa, 288.15 K). The compressor models were designed with 12 full blades, and the blade thickness for the compressor models was set at 1.3 mm. CFD analyses were carried out at three different operating speeds, namely 45.500, 55.500 and 65.500 rpm, with the same mass flow rates (1 kg/s) and pressure ratios (4.8). The energy efficiencies of these models were determined as 94.29%, 94.44% and 94.68%, respectively. Then, traditional exergy analyses were found to be 79.25%, 86.02% and 81.70%, respectively. In this study, computational fluid dynamics (CFD) and thermodynamic analyses of the radial compressor blade, one of the key components of the small-scale micro turbojet engine used for propulsion in UAV’s, were conducted. The micro turbojet engine was analyzed under sea level conditions (101.325 Pa, 288.15 K). The compressor models were designed with 12 full blades, and the blade thickness for the compressor models was set at 1.3 mm. CFD analyses were carried out at three different operating speeds, namely 45.500, 55.500 and 65.500 rpm, with the same mass flow rates (1 kg/s) and pressure ratios (4.8). The energy efficiencies of these models were determined as 94.29%, 94.44% and 94.68%, respectively. Then, traditional exergy analyses were found to be 79.25%, 86.02% and 81.70%, respectively.

Air transport is one of the important pillars of the transport mechanism. The aviation sector is the most fundamental and primary field of endeavor as it provides military, political and economic superiority to the strategic interests of countries. Countries that have a say in the sector proactively prepare themselves for the requirements of the era and the future and carry out their activities in this direction. The reason for these studies is shown as the desire to gain superiority in the ever-increasing economic competition and to increase the brand value of the country in the field of aviation. G20 countries are the world's leading and powerful economies. The share of the aviation sector in this economic power is quite high. The aim of this study is to determine the operational and financial efficiency levels of G20 countries and Turkey in the field of aviation. By evaluating the internal dynamics of the airspace, the deficiencies of Turkey in the aviation sector against the G20 countries are evaluated by analyzing both the impact of developing technology and globalization and some negative changes brought about by the COVID-19 pandemic. Using the data envelopment analysis (DEA) method, in the light of accurate and reliable results, Turkey's position in the aviation sector against the G20 countries is evaluated with approaches based on analytical and objective methods, and how it can raise itself to a higher position in the world aviation ranking by identifying the issues it lacks. It is expected to be useful for researchers working on this subject.

Today, microstrip antennas are preferred in many aerospace applications such as high performance vehicles, aircraft, military aircraft, Unmanned Aerial Vehicles (UAVs), spacecraft, radar systems, satellite and missile applications. In this study, the use of microstrip patch antennas in the aerospace industry and especially in global positioning systems (GPS) has been investigated and a sample microstrip patch antenna design has been realized in the GPS L5 security band. The designed antenna with high gain and circular polarization is simulated with High Frequency Structural Simulator (HFSS) and the results are analyzed. Numerical analysis of the simulations showed that at the center frequency of 1176 MHz, the S11 value was -38.85 dB, the bandwidth was 54 MHz and the gain was 6.07 dBm. As a result of these values, it is concluded that it can be used in the global positioning L5 security band.