Kocamer, Abdullah; Kose, Oguz; Şal, Firat; Oktay, Tugrul

Purpose The purpose of this paper is to investigate the impact of dihedral angle manipulation on the aerodynamic performance and optimization of vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV) wings through morphing techniques. Design/methodology/approach Morphing operations with variable dihedral angles were implemented on three-dimensional models of VTOL UAV wings. The resulting moments of inertia were analyzed, and aerodynamic performance was optimized using the simultaneous perturbation stochastic approximation (SPSA) method. Control models were applied to evaluate the impact of morphing on the aerodynamic characteristics of the wings. Findings This research highlights the critical role of dihedral angle adjustments in improving flight stability, energy efficiency and overall aerodynamic performance. The combination of computational modeling and optimization techniques, such as SPSA, contributes to an enhanced understanding of the morphological adaptations required for optimal UAV performance. Originality/value This study provides a novel approach to UAV design by focusing on dihedral angle manipulation for aerodynamic performance optimization. The integration of morphing techniques, control models and optimization techniques presents a significant step forward in developing efficient VTOL UAVs.

Can, Erol; Kilic, Ugur

Purpose: Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high frequency for electrical devices is used to reduce the weight of the cables in the aircraft and spacecraft because of the skin effect. In the high-frequency system, a thinner cable cross-section is used, and a great weight reduction occurs in the aircraft. So, fuel economy, less and late wear of the materials (landing gear, etc.) can be obtained with decreasing weight. This paper aims to present the development of a functional multilevel inverter (FMLI) with fractional sinus pulse width modulation (FSPWM) and a reduced number of switches to provide high-frequency and quality electrical energy conversion. Design/methodology/approach: After the production of FSPWM for FMLI with a reduced component, which, to the best of the authors’ knowledge, is presented for the first time in this study, is explained step by step, and eight operating states are given according to different FSPWMs operating the circuit. The designed inverter and modulation technique are compared by testing the conventional modular multilevel inverter on different loads. Findings: According to application results, it is seen that there is a 50% reduction in cross-section from 100 Hz to 400 Hz with the skin effect. At 1000 Hz, there is a 90% cross-section reduction. The decrease can be in cable weights that may occur in aircraft from 10 kg to 100 kg according to different frequencies. It causes less harmonic distortion than conventional converters. This supports the safer operation of the system. Compared to the traditional system, the proposed system provides more amplitude in converting the source to alternating voltage and increases the efficiency. Practical implications: FSPWM is developed for multilevel inverters with reduced components at the high frequency and cascaded switching studies in the power electronics of aircraft. Social implications: Although the proposed system has less current and power loss as mentioned in the previous sections, it contains fewer power elements than conventional inverters that are equivalent for different hardware levels. This not only reduces the cost of the system but also provides ease of maintenance. To reduce the cable load in aircraft and create more efficient working conditions, 400 Hz alternative voltage is used. The proposed system causes less losses and lower harmonic distortions than traditional systems. This will reduce possible malfunctions and contribute to aircraft reliability for passengers and cargo. As technology develops, it is revealed that the proposed inverter system will be more efficient than traditional inverters when devices operating at frequencies higher than 400 Hz are used. With the proposed inverter, safer operation will be ensured, while there will be less energy loss, less fuel consumption and less carbon emissions to the environment. Originality/value: The proposed inverter structure shows that it can provide energy transmission for electrical devices in space and aircraft by using the skin effect. It also contains less power elements than the traditional inverters, which are equivalent for different levels of hardware.

Kose, Oguz

Purpose: This study aims to discuss the simultaneous longitudinal and lateral flight control of the octorotor, a rotary wing unmanned aerial vehicle (UAV), for the first time under the effect of morphing and to improve autonomous flight performance. Design/methodology/approach: This study aims to design and control the octorotor flight control system with stochastic optimal tuning under morphnig effect. For this purpose, models of different arm lengths of the octorotor were drawn in the Solidworks program. The morphing was carried out by simultaneously lengthening or shortening the arm lengths of the octorotor. The morphing rate was estimated by using simultaneous perturbation stochastic approximation (SPSA). The stochastic gradient descent algorithm, which is frequently used in machine learning, was used to estimate the changing moments of inertia with the change of arm lengths. The proportional integral derivative (PID) controller has been preferred as an octorotor control algorithm because of its simplicity of structure. The PID gains required to control both longitudinal and lateral flight were also estimated with SPSA. Findings: With SPSA, three longitudinal flight PID gains, three lateral flight PID gains and one morphing ratio were estimated. PID gains remained within the limits set for SPSA, giving satisfactory results. In addition, the cost index created was 93% successful. The gradient descent algorithm used for the moment of inertia estimation achieved the optimum result in 1,570 iterations. However, in the simulations made with the obtained data, longitudinal and lateral flight was successfully carried out. Originality/value: Octorotor longitudinal and lateral flight control was performed quickly and effectively with the proposed method. In addition, the desired parameters were obtained with the optimization methods used, and the longitudinal and lateral flight of the octorotor was successfully carried out in the desired trajectory.

Kilic, Ugur

Purpose: This study aims to examine turboprop- and turbofan-powered aircraft, with the same seating capacity flying on the same route and trajectory, and investigate their environmental effects. Design/methodology/approach: The integrated aircraft noise and emissions modeling platform developed by EUROCONTROL is used for the calculation of fuel burn, CO2, H2O and other gas emissions (NOx, SOx, CO, HC, soot and other trace compounds) for the per phase of flight. Findings: The striking findings are that turboprop-powered aircraft offer lower required thrust, fuel consumption and total emissions for a short-haul flight, but turbofan-powered aircraft have lower particulate matter, CO and HC emissions than turboprop-powered aircraft. This study suggests that turboprop-powered aircraft are superior to turbofan-powered aircraft in terms of environmental impact for a short-haul flight. Practical implications: The current research conducts comprehensively fuel consumption and amounts of emissions aspects of turboprop- and turbofan-powered aircraft for sustainable development of airlines by a versatile simulation approach and sheds light on airlines intending to create fleets. Originality/value: The research offers a systematic aircraft selection for investigators, scientists, airline operators, policy analysts and legislators, by a comprehensive computer simulation method that acknowledges consistently the fuel consumption and detailed emissions analysis of turboprop- and turbofan-powered aircraft.

Kose, Oguz; Oktay, Tugrul; Özen, Enes

Purpose: The purpose of this paper is to obtain values that stabilize the lateral and longitudinal flight of the quadrotor for which the morphing amount and the best Proportional-Integral-Derivative (PID) coefficients are determined by using the simultaneous perturbation stochastic approximation (SPSA) optimization algorithm. Design/methodology/approach: Quadrotor consists of body and arms; there are propellers at the ends of the arms to take off and rotors that rotate them. By reducing the angle between mechanism 1 and the rotors with the horizontal plane, the angle between mechanism 2 and the arms, the rotors rise and different configurations are obtained. Conventional multi-rotor aircraft has a fixed fuselage and does not need a tail rotor to change course as helicopters do. The translational and rotational movements are provided by the rotation of the rotors of the aircraft at different speeds by creating moments about the geometric center in 6-degree-of-freedom (DOF) space. These commands sent from the ground are provided by the flight control board in the aircraft. The longitudinal and lateral flight stability and properties of different configurations evaluated by dynamic analysis and simulations in 6 DOF spaces are investigated. An algorithm and PID controller are being developed using SPSA to achieve in-flight position and attitude control of an active deformable aircraft. The results are compared with the results of the literature review and the results of the previous article. Findings: With SPSA, the best PID coefficients were obtained in case of morphing. Research limitations/implications: The effects of quadrotor arm height and hub angle changes affect flight stability. With the SPSA optimization method presented in this study, the attitude is quickly stabilized. Practical implications: With the optimization method, the most suitable PID coefficients and angle values for the lateral and longitudinal flight stability of the quadrotor are obtained. Social implications: The transition rate and PID coefficients are determined by using the optimization method, which is advantageous in terms of cost and practicality. Originality/value: With the proposed method, the aircraft can change shape to adapt to different environments, and the parameters required for more stable flight for each situation will be calculated, and this will be obtained more quickly and safely with the SPSA optimization method.

Aydoğan, Emre; Demirel, Soner

Purpose: The purpose of this paper is to create and analyze the effectiveness of a new runway system, which is totally created for the future free route operations. Design/methodology/approach: This paper researches and analyses the new generated runway concept with the fast time simulation method. Fuel consumption and environmental effect of the new runway system are calculated based on simulation results. Findings: According to different traffic density analyses the Omnidirectional Runway with Infinite Heading (ORIH) reduced fuel consumption and CO2 emissions up to 46.97%. Also the total emissions of the ORIH concept, for the hydro carbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx) pollutants were lower than the total emissions with the conventional runway up to 83.13, 74.36 and 51.49%, respectively. Practical implications: Free route airspaces bring many advantages to air traffic management and airline operations. Direct routes become available from airport to airport thanks to free route airspace concept. However, conventional single runway structure does not allow aircraft operations for every direction. The landing and take-off operations of a conventional airport with a single runway must be executed with only two heading direction. This limitation brings a bottleneck direct approach and departure route usage as convenient with free route airspace concept. This paper suggests and analyzes the omnidirectional runway with infinite heading (ORIH) as a solution for free route airspace. Originality/value: This paper suggests a new and futuristic runway design and operation for the free route operations. This paper has its originality from the suggested and newly created runway system.