نشریه فناوری در مهندسی هوافضا
سال پنجم شماره 4 (پیاپی 19، زمستان 1400)

In this paper, the modeling method of aircraft aerodynamic responses to the 1-cos gust profile is presented. Test cases considered are, a two-dimensional NACA0012 airfoil was used to verify the method and two-dimensional NACA23012, NACA23015, and NACA23016.5 airfoils of the wing of a light aircraft and three-dimensional wing of the same aircraft in Mach numbers 0.1, 0.2 & 0.3. The test cases are assumed to be rigid and only gust profiles are considered longitudinal. The simulation results show that the aerodynamic responses of 1-cos gust agree well with Küssner approximate function. In the two-dimensional mode for a particular airfoil, as the Mach number increases, the amplitude of the incremental lift coefficient due to the gust increases, and the wavelength decreases. As the thickness of the airfoil in a Mach number increases, the amplitude remains constant, but the wavelength increases. In the three-dimensional mode, for a wing by increasing the Mach number, the amplitude increases and the wavelength remain constant.

Most spacecraft components have a specific allowable temperature limit that must be met for optimal operation and subsystem survival. The adjustment of this temperature range is made by various active and passive thermal management techniques. Passive thermal control methods do not consume satellite electrical power; meanwhile they are low cost, low volume, lightweight, efficient, and operationally risk-free. Hence, space system designers find them particularly appropriate, especially for small systems such as CubeSats. In addition to conventional thermal management tools, revolutionary technologies such as sunshields, flat bendable heat pipes, deployable radiators, thermal louvers, variable emittance radiators, thermal storage units, and pyrolytic graphite film thermal straps have been successfully demonstrated. This paper includes an overview of innovations and achievements in the passive thermal control of CubeSats.

The thermal control subsystem (TCS) of satellites is responsible for providing and maintaining the allowable temperature of that satellite equipment. Naturally, if this subsystem is not properly designed, other subsystems, including the payload, will not be able to do their duties. In general, there are two active and inactive methods for designing TCS. Studies show that the elements can be suitable for controlling the temperature of a small-scale satellite (SSS) which has low weight, volume, and power consumption. Therefore, passive temperature control this equipment is widely used in SSS. The most common of these equipment are coatings, insulators, and paints. But some active elements are commonly used to make the thermal design of small satellites safer. Heaters are more common among thermally active elements, because they .have less volume and weight than other active equipment, and consume less power than other elements

Today, Carbon fiber-reinforced polymer composites (CFRP) have extensive use in different fields such as aerospace, automotive, oil, gas, and defense industries compared to metals, due to the high ratio of strength to weight. Machining of these materials regard to their non-homogeneity structure is complicated. Due to the different thermal expansion coefficients between the fibers and resin polymer composite milling materials difficult to create one of the final parts. Achieve optimal machining conditions, with high efficiency, which need proper analysis and careful investigation. Minimizing the machining time became important Due to developments in CNC technology. One of the time minimizing methods is high-speed machining technology. In this study, composite plates made of carbon/epoxy to a thickness of 10 millimeters, which are often used in the body of Aerospace structures and missiles, have been manufactured by hand layup. The cutting parameters used during the milling operation of the CFRP panel ranged from 1000 rpm to 7000 rpm for the spindle speed, feed rate from 1000 mm/min to 3000 mm/min, and lastly 1.0 mm to 3.0 mm range for depth of cut. the combination of spindle speed, feed rate, and depth of cut are studied at five different levels. 20 runs of experiments are performed based on Response Surface Methodology (RSM). the milling process with two-flute tungsten carbide - coated diamond insert with a 20 mm diameter was performed. their surface quality after milling process is measured. So after roughness, material removal rate and required analysis were performed. Spindle speed has a greatest effect on surface roughness. In conclusion, the influence of the cutting parameters is higher spindle speed, lower feed rate, and lower depth of cut resulting in low surface roughness. The optimized cutting parameters were spindle speed, feed rate, and depth of cut of 7000 rpm, 1000 mm/min and 1 mm respectively with the surface roughness of 1.9 um.

One of the most important and complex issues in the field of aerospace engineering is the returning to the atmosphere. Many flying objects do not experience returning to the atmosphere. The study of this topic is relevant only to those flying objects that have left the atmosphere and their return to the atmosphere is important for some reason. Different missions and constraints in the discussion of entering the atmosphere have led to the development of different methods, each of which has its advantages and disadvantages, which is currently one of the current aerospace research scopes. This article introduces the most important atmospheric reentry guidance methods based on trajectory generation. This paper only considers closed-loop guidance methods.

Adhesives and adhesive joints have replaced conventional methods such as riveting, welding, and mechanical joints as a valuable way for assembling space structures, due to their significant reduction in spacecraft mass and also having optimum properties (high mechanical, electrical, and thermal properties, simultaneously, appropriate to the application). Space adhesives, in addition to having unique properties, have the ability to be used for a long time and are resistant to the space environment. These adhesives are used to bond similar structures (metal or composite) and metal / composite structures. In this research, an attempt has been made to introduce the types of adhesives, their production methods, and theire application. The space environment and its components such as energetic charged particles, solar electromagnetic radiation and atomic oxygen are introduced and finally the effect of the components on their properties and mechanisms of their destruction are discussed