نشریه فناوری در مهندسی هوافضا
سال هفتم شماره 3 (پیاپی 26، پاییز 1402)

The success of missions and related costs has always been one of the concerns of researchers and due to the sensitivity and variety of missions, this issue is more important today. In the past decade, group fly is more investigated because of their influence on the quantity and quality of missions. In this research, an Unmanned Air Vehicle (UAV) system that includes several UAVs that has a parallel structure and able to perform different missions to detect, follow and attack, has been considered. The UAV success rate is be defined according to the UAV conditions, the amount of failure, and the type of failure. it is assumed that its failure rate is not constant and has multistate behavior, also It has the ability to perform different operations assigned randomly, Universal generation function, and Markov chain methods for modeling are be developed. A UAV system has been considered and, the ability and accuracy of these methods are be demonstrated.

In recent years, the use of air taxis as a suitable solution for transporting cargo and passengers, has been considered especially in short distances and in the city. Complex systems, such as air taxis, are involved in several subsystems with interacting and sometimes conflicting effects are difficult to be derived. Modern optimal design methods such as multidisciplinary design optimization can derive the optimal design while satisfying all the constraints and limitation. In this article, multidisciplinary design optimization of an air taxi is discussed. The optimization framework is selected based on AAO by considering structure, aerodynamics, flight mechanics, propulsion and electrical power. Total mass of air taxi is selected as cost function. Finally, the optimal results are compared and evaluated with the results of two classical design methods including "weight estimation" and " sensitivity of design coefficients". The results confirm the improvement of optimal solution with compare of classical methods.

In the present study, the large deflection of nanobeams with surface effects has been investigated. The surface effects are modeled by using the generalized Young–Laplace equation. The finite element method has been used to investigate the mechanical behavior of nanobeams. This method provides the possibility of solving the problem with the least assumptions and with the arbitrary boundary conditions and geometry. With the use of the proposed model, nanobeams small to large deflection with different loading and support conditions can be analyzed. In this study, the large deflection of circular cross-sectional nanobeams under sinusoidal distributed load with surface effects has been investigated. The effect of various parameters such as aspect ratio, surface elastic modulus and residual surface stress on the large deflection of nanobeams has been investigated. The result obtained show the importance of considering the surface effects in the study of large deflection of nanobeams.

Studies are currently being conducted around the world to realize advanced air Mobility. Advanced Air Mobility is expected to solve various regional issues and provide people with new forms of air transportation. In this article, air travel is investigated as a significant option for improving transportation networks within and between different cities and regions in Iran, and Iran's market profile for accepting Advanced Air Mobility is investigated. Also, the challenges and issues facing Advanced Air Mobility have been studied, finally, some existing plans for use in various missions of Advanced Air Mobility and future mechanisms and plans for the realization and development of this field in Iran have been proposed.

Studies show that the analysis of the first law in air propulsion systems alone is not sufficient, and for a complete study of a system, the second law and exergy analysis should also be considered. Thermodynamic analysis of air-breathing engines, especially Turbojet, Turbofan and Turboprop engines, with the aim of studying their performance has attracted the attention of many researchers in the last decade. The main purpose of this study is to review and present the latest research findings in this field focusing on Turbojet, Turbofan and Turboprop engines. The results of further research show that the combustion chamber and afterburner are the two most important parts of air engines in which the most exergy destruction occurs. On the other hand, the study and analysis of engine exergy off design point is also an important issue that has been considered in recent years.

Helicopters can be a source of loud noise. The high production noise of helicopters makes them unsuitable for densely populated areas, especially in low-flying conditions. This study examines methods and offers solutions to reduce or eliminate the noise produced by helicopters. Several methods have been considered to reduce the noise produced. Solutions such as muffler for motors, use of modulated blade spacing, X-force control, reduced tip speed, blade tip modification, airfoil tailoring, Increasing the number of main rotor blades, active blade control and variable diameter rotor in The rotor and the use of the strut in the gearbox were introduced. According to the studies conducted in the present study, combined methods haveas the best noise reduction. although Independent methods reduce noise, depending on the amount of reduction required in the targeting, combining the methods can be achieved the appropriate answer.