Asrel Aerospace Research Letters Current Issue

In the aviation sector, studies are carried out to reduce the design weights and increase their strength. With these studies, a search for suitable materials has been started and a composite class with high strength, light weight and low cost has emerged, where the desired mechanical properties can be obtained. However, the inability to recycle thermosets was not an adequate solution. Despite the deterioration of the world's ecosystem and the increase in the pollution level of nature, green composites have started to be produced in order to minimize the damage to nature, and studies on this subject have increased and continue to increase day by day. The aim of this study is to observe the resistance that the aircraft can provide to the external pressure load by producing Polyamide- Nylon 6/6 50% Long Glass Fiber Reinforced composite in the main body of the aircraft. In the stress analysis studies, the virtual test method was used to save real test cost and time. Virtual tests were carried out with the MSC Apex finite element analysis program. The fact that the MSC Apex application was a special study for composite laying played an important role in the preference of MSC Apex in the study. The point to be noted in the study is to emphasize that these studies that will be beneficial to the ecosystem should be given importance. Considering the stress distribution and sizes resulting from the analysis results, it is seen that although the material is 12.8 mm (thicker than normal), the material is not suitable for the 28.5psi pressure load created by targeting NASA conditions.

Fighter jets can face serious problems during flight. One such problem is turbulent air entering the air intake and the resulting boundary layer during flight. To prevent these issues and increase engine performance, a diverter is designed and used. The diverter is a component placed between the body and engine and evacuate highly turbulent air away from the engine before it is taken in. This study aims to calculate and analyze the most commonly used Channel Type Boundary Layer Diverter, which covers both internal and external flow, in supersonic aircraft due to its high-performance, high-pressure recovery, and low weight requirements. The F-22 Raptor fighter plane was selected for analysis. The geometry of the aircraft up to the air intake was obtained, and analysis was conducted using the Ansys-Fluent program at a speed of M=0,8 to determine the boundary layer thickness. The height of the diverter was adjusted based on the obtained boundary layer thickness. Models with diverter and diverterless were created in 3D, and computational fluid dynamics (CFD) analyses were conducted to examine motor performance parameters. These analyses were conducted at speeds of M=0,8, M=1,2, and M=1,6 at an altitude of 30,000 ft. To correctly resolve the boundary layer section and ensure that the SST-kw turbulence model works correctly, the y+ value was kept below 1. Additionally, a transition mesh structure was created to detect the viscous region. Independence studies were conducted under flow volume-defined boundary conditions. The values obtained were compared with similar studies in the literature to evaluate their accuracy. The results showed that the diverter reduced drag coefficient and boundary layer thickness while increasing mass flow rate and pressure recovery.

In this study, a model rocket is designed for given mission parameters. Also, it is explained how a rocket prototype is produced and what parameters are used in the design phase. The design parameters may vary completely for different tasks and requirement configurations. The objective of this paper is to explain the design steps and performance analyses of a model rocket prototype. The rocket is designed from the beginning with the goal of high apogee and a higher payload. Design steps and simulations are demonstrated, and rockets are manufactured by evaluating the optimization. Nose cone, fin, and material strength calculations in rockets are performed in detail to prevent the drawbacks of instabilities. The manufacturing of the model rocket, its design, and the simulation of the rocket prototype are successfully done.

Sustainability, which is an issue that is becoming increasingly important in the world and has just begun to be discussed in Turkey, is a concept that should be understood by all levels of society. Because sustainability is not an issue that can be carried out by certain individuals or segments of society, it is an issue that should be among the strategic priorities of governments and become a way of life for societies. In this study, it is aimed to examine the sustainability reports published by Turkish Airlines (THY), Turkey's flag carrier airline and a global brand, between 2014 and 2021, with the content analysis method, and to analyze the indicators included in the reports and the practices. According to the evaluations made within the scope of the study, sustainability reports are visually successful and contain extensive data about the sector and THY. Over the years, differences have been made both in the general framework and in the content. When the presented data are compared side by side, it is seen that there are deficiencies and inconsistencies and traceability cannot be ensured. It is recommended that sustainability reports be developed in line with the principles of reliability, transparency, traceability and auditability in the coming years and published as an example for all stakeholders.

In this study, a sandwich panel that can be used as an internal structural material in aircraft and other transportation vehicles has been produced. The core of this sandwich panel was obtained by baking neat EVA sheets without reinforcement and with three rows of steel wire reinforcement at 180 ˚C for 30 minutes. On the upper and lower surfaces of these cores, 0.5 mm thick 5457 aluminum sheets were adhered with polyurethane adhesive and thus composite panels were obtained. The sandwich panels were subjected to impact tests at various levels (20J, 30J, 40J and 50J). After the tests, force-time and force-displacement graphs of the specimens corresponding to different energy values were obtained. It was observed that as the wire reinforcement increases, the elasticity of the material decreases and the strength of the material increases, and accordingly, the maximum displacement generally decreases.

Metal additive manufacturing (M-AM) processes are still seen as non-conventional in the industry, and they are considered for niche applications rather than mass production. The major determinant in the industry is the production time and unit cost. Casting, metal forming, and most machining processes are matured and optimized for low to medium-cost mass production; however, a large portion of manufacturing includes customization and there are also many products that are made only one or in very small quantities, where M-AM processes may be a good alternative to conventional manufacturing. Then, understanding the strengths and weaknesses of M-AM is critical in selecting the most technically and economically feasible option. Classifying the M-AM processes as fusion-based and solid-state is important in the sense that there are significant differences in the material properties and geometric precision provided by each category. Overall, fusion-based technologies yield net-shape parts with material properties close to casting. On the other hand, solid-state processes produce “near-net-shape” geometries; however, material properties may be superior. Nevertheless, almost in all cases, some post-processing including a surface finish operation is required.