The quadcopter as one of the UAV (Unmanned aerial vehicles) is inherently unstable, and has six degrees of freedom (6 DOF), while the number of control inputs is four. The present work presents a sequential methodology to analyze and explain the control mechanism of quadcopter‐UAV in academic and research institutions. This methodology includes simulation, modelling, attitude control, Hardware in‐the Loop (HIL) testing methodology, performance evaluation, and an experimental testing platform. Coordinate systems, kinematics, and dynamics systems are derived in great detail. Then, a real‐time test platform is designed to verify system stability in a safe environment. (HIL) simulation was performed by the Pixhawk flight controller board interfaced with the Mission Planner platform. The numerical results include the control parameters of the quadcopter position (phi, theta, psi), and the translation values. The simulation results showed high and reliable performance both at the desired roll, pitch, and yaw angles as well as at the quadcopter position in the coordinate axes. Furthermore, the results of the real‐time experiments (indoor/outdoor flight tests) have successfully demonstrated good stability and high response. Based on the methodology used in this research, the cost and risk of real‐time flight experiments for UAVs have been reduced.

This study is conducted in the context of two significant challenges facing Unmanned Aerial Vehicle (UAV) technologies. These challenges are limited flight duration and payload, which have a direct impact on the performance and areas of application. The Hybrid Power System (HPS) has a prominent role in overcoming these challenges with a view to expanding the application fields of UAVs to include further areas such as air taxis and air ambulance services. First, this work systematically reviews the scientific contributions in the past two decades with the aim of exploring the existing design approaches for HPSs in multi-rotor UAVs. To do that, a Systematic Literature Review (SLR) has been followed. The selected articles have been reviewed, analyzed, evaluated, and then classified according to the scope of the study, research trends, design methodologies, main findings/shortcomings, and future work. Retrieved data shows that the Internal Combustion Engine (ICE) and the Proportional-Integral-Derivative (PID) controller were the most commonly used. Fuel Cells (FCs) still need more research and experiments to overcome practical constraints, while solar-powered UAVs require more surface areas to absorb large amounts of solar radiation. Second, to keep up-to-date with technological advances in this area, this research surveys, analyses, and discusses the available commercial models of HPS that can be used in UAVs along with some examples of hybrid-powered UAVs. The intended goal of this paper is to stimulate and help researchers and those interested in the challenges of electric UAVs and guide them to develop this field more efficiently from an industrial/scientific perspective.

The title cyclobutyl compound, C₁₈H₁₈N₂O₃S, was synthesized by the interaction of 4-(3-methyl-3-phenylcyclobutyl)thiazol-2-amine and maleic anhydride, and crystallizes in the orthorhombic space group P2₁2₁2₁ with Z′ = 1. The molecular geometry is partially stabilized by an intramolecular N—H...O hydrogen bond forming an S ₁ ¹(7) ring motif. The molecule is non-planar with a dihedral angle of 88.29 (11)° between the thiazole and benzene rings. In the crystal, the molecules are linked by O—H...N hydrogen bonds, forming supramolecular ribbons with C ₁ ¹(9) chain motifs. To further analyze the intermolecular interactions, a Hirshfeld surface analysis was performed. The results indicate that the most important contributions to the overall surface are from H...H (43%), C...H (18%), O...H (17%) and N...H (6%), interactions.

The title compound, C₄H₉N₅ ²⁺·2NO₃ ⁻, crystallizes in the monoclinic crystal system, space group P2₁/c. The asymmetric unit, which comprises a diprotonated triaminopyrimidine dication and two nitrate anions, has an almost planar geometry with a dihedral angle of 0.92 (4)° between the mean plane of the cation and that defined by both anions. In the crystal, hydrogen-bonding interactions between the 2,4,6-triaminopyrimidine cation and the nitrate anions lead to a one-dimensional supramolecular network with weak anionic interactions forming a three-dimensional network. These interactions were investigated using Hirshfeld surface analysis, which indicates that the most important contributions for the packing arrangement are from O...H/H...O (53.2%), N...H/H...N (12.5%) and C...H/H...C (9.6%) interactions. Energy framework analysis showed that of the components of the framework energies, electrostatic repulsion (E _rep) is dominant.

The title compound, C₁₃H₁₄N₄O, was developed using the reaction of salicylaldehyde and 3-amino-5-cyclobutyl-1,2,4-triazole in ethanol under microwave irradiation. This eco-friendly microwave-promoted method proved to be efficient in the synthesis of 2-{[(E)-(3-cyclobutyl-1H-1,2,4-triazol-5-yl)imino]methyl}phenol in good yields and purity. The title compound is a Schiff base that exists in the phenol–imine tautomeric form and adopts an E configuration. The three independent molecules in the asymmetric unit (A, B and C) are not planar, the cyclobutyl and the phenol-imine rings are twisted to each other making a dihedral angle of 67.8 (4)° in molecule A, 69.1 (2)° in molecule B and 89.1 (2)° in molecule C. In each molecule an intramolecular O—H...N hydrogen bond is present, forming an S(6) ring motif. A Hirshfeld surface analysis was performed to investigate the contributions of the different intermolecular contacts within the supramolecular structure. The major interactions are H...H (53%), C...H (19%) and N...H (17%) for molecule A, H...H (50%), N...H (20%) and C...H (20%) for molecule B and H...H (57%), C...H (14%) and N...H (13%) for molecule C.

This article explores hybrid power systems (HPSs) as a promising solution to enhance payload (PL) capacity and flight endurance (FE), promoting the adoption of electric vertical takeoff and landing (eVTOL) technology for urban air mobility (UAM). First, a review of relevant aviation technologies, including fully electric and hybrid eVTOL vehicles, is conducted. Second, an algorithm is introduced, systematically utilizing key performance metrics such as maximum takeoff weight (MTOW), power-to-MTOW, fuel weight (FW), FE, and total energy (TE) generation. A new metric, usable weight (UW), is proposed to quantify the increase in FE or PL capacity. Third, five distinct hybrid power unit (HPU) case studies are analyzed based on the proposed algorithm, incorporating a supercar piston engine (PE), a turboshaft engine (TSE), a Wankel engine, a fixed-wing adapted engine, and a new proposed engine. Each HPU is virtually run with a predefined flight profile. This analysis estimates FE, TE, and total FW, highlighting that the proposed PE represents a tradeoff between power, weight, and fuel efficiency. Fourth, a comparative framework evaluates the TE output of five HPUs and a fuel cell (FC)–battery hybrid system from the literature, each with a maximum power output of 450 kW, for a 2000-kg MTOW eVTOL and a powertrain weight limit of 560 kg (including fuel). Fifth, seven commercial aircraft PEs were assessed for their suitability as prime movers in eVTOL UAM applications. The analysis identified only one candidate engine, with a power-to-weight ratio (PWR) of 1.4 kW/kg, capable of delivering FE of $\ge 1$ h. Finally, virtual aviation engines with power outputs up to 450 kW (dual 225-kW configuration) and PWR spanning 1–3 kW/kg were investigated. Results demonstrate that engines with PWR $\le 1.1$ kW/kg fail to satisfy the minimum power density requirements for sustained eVTOL FE ( $\ge 1$ h). By establishing a systematic framework for HPU prime mover selection, this study advances the design of next-generation eVTOLs for UAM with medium-to-long endurance capabilities while simultaneously providing actionable insights to connect academic research with industrial development.