Asrel Aerospace Research Letters Latest Issue

This study presents a numerical investigation of the drop impact response of the landing gear system of a coaxial drone subjected to a low-altitude free-fall scenario. The primary objective is to evaluate the structural integrity and impact resistance of the landing gear during landing events, providing critical feedback for design enhancement. A detailed geometric model of the drone and its landing gear components was developed using SolidWorks, and meshed with tetrahedral and eight-node solid elements. The dynamic impact event was simulated using explicit finite element solver, modeling a vertical free fall from 50 cm with an initial velocity of approximately 3.13 m/s. Aluminum 7075-T6 was selected as the structural material due to its favorable strength-to-weight characteristics, with plastic behavior modeled using the Johnson–Cook constitutive model. Energy components were monitored to ensure numerical stability throughout the simulation process. The results showed that the maximum equivalent (von Mises) stress, approximately 551 MPa, occurred at the root plate where the landing gear is connected to the main body, exceeding the material’s yield strength by nearly 15% and leading to localized plastic deformation. In contrast, stress levels in other regions, such as the body panels, remained within the elastic range (200–350 MPa). The peak effective plastic strain was limited to 2.1%, predominantly concentrated around the landing gear leg-to-body interface. These findings indicate that the majority of the impact energy was dissipated locally, allowing the overall structure to maintain its integrity. In conclusion, the structural assessment confirmed the integrity of the landing gear under impact loading; however, significant stress concentrations were observed near the connection region. Reinforcing this area and improving local stiffness to achieve more uniform stress distribution are recommended. The outcomes of this study provide useful design insights to enhance the drop impact performance and reliability of coaxial UAV landing gear systems.

In this study, a low-velocity impact test was numerically simulated on Kevlar-29/Epoxy laminates with dimensions of 100 × 100 mm and a thickness of 6 mm, arranged in [0/45/90]₄, [0/30/60/90]₃, and [0/90]₆ orientation sequences using the LS-DYNA software. The impact loading was applied by a 6 mm-diameter impactor with a mass of 15 kg striking the laminates at a velocity of 5.0 m/s. The maximum force values varied depending on the lay-up sequence, and the highest peak force was obtained in the [0/30/60/90] configuration with 45 N. In the energy–time analysis, it was observed that the total energy transferred during the impact was approximately 187.5 J for all three configurations. This impact result suggests using isotropic approach paving rows using different paving methods to maximize energy absorption and increase damage tolerance.

Today, many different propulsion systems have been developed for use in space. However, chemical propulsion systems are not considered sufficient for interstellar missions due to their low specific impulse values, while ion propulsion systems are not considered sufficient due to their low thrust levels. Although fission and fusion-based photonic propulsion systems offer high efficiency and potential speed values, due to current technological limitations and the vastness of interstellar distances, it does not seem possible for even these systems to reduce the time required to reach the nearest stars, such as Alpha Centauri, to reasonable levels. This study aims to compare different propulsion systems for the Alpha Centauri mission through numerical modeling. Speed, acceleration, and arrival times were calculated for each system, and performance analyses were conducted based on the numerical results. According to the findings, even under ideal conditions, the fusion-based propulsion system, which showed the highest performance, was calculated to take 1,674 years to reach Alpha Centauri. This value reveals that both this system and other existing propulsion types are inadequate for interstellar missions when compared to the lifespan of humans.

Accurate calculation of the return on investment periods for solar power plants depends heavily on the reliability of simulations performed prior to installation. In this study, a performance analysis was conducted for an operational 992.25 kWp grid-connected photovoltaic power plant located in Şereflikoçhisar, Ankara, within the Central Anatolia Region, which possesses high solar energy potential. Within the scope of the study, the geographical location of the plant along with the specific characteristics of the photovoltaic modules and inverters used were modeled exactly in simulation environments. The prediction accuracy of PVsyst and PVGIS software was then compared against one year of actual field (SCADA) data. The analysis revealed that the actual annual generation of the plant was 1,528,217 kWh. Under the same meteorological conditions, the PVsyst software predicted 1,458,184 kWh with a negative deviation of 4.6%, while the PVGIS software predicted 1,542,669 kWh with a positive deviation of 0.94%. The findings demonstrate that while PVGIS aligns closely with field data regarding total production estimation, PVsyst serves as an indispensable engineering tool for the detailed analysis of loss parameters such as temperature and soiling. In this context, it is recommended that investors use both software tools for cross-verification during the feasibility phase.

Unmanned Aerial Vehicles (UAVs) have an increasingly important role in many civilian and military fields such as defense, agriculture, logistics, and surveillance. With advancements in technology, the performance, durability, and operational efficiency of UAVs have also improved significantly. One of the most critical factors in meeting these expectations is the type of materials used in the manufacturing of the UAV airframe. The materials selected for the airframe structure directly affect the vehicle’s weight, fuel or energy consumption, maneuverability, and overall reliability. This article examines the main materials currently used in UAV airframe structures, discusses the reasons for their use, and compares different material types from mechanical, structural, and economic perspectives. As a result of these comparisons, material selection during the UAV manufacturing process can be more easily categorized and systematized.