Aviation

Simulation and evaluation of lateral/directional dynamics in an aircraft autopilot control system

2024-11-27T18:29:12+02:00

The objective of the research was to design and simulate the lateral/directional dynamics control of an aircraft’s autopilot system to automate the landing approach execution, complying with the requirements of the Instrument Landing System (CAT III C). The design methodology involved integrating a Linear Quadratic Regulator (LQR) with Affine Parameterization techniques to create a robust control system. The prototype was developed using Matlab and simulated in Simulink. Through various simulations, adjustments were made to the Q and R matrices of the LQR controller based on Bryson’s rule, allowing the system to adapt to the nonlinearities and dynamic constraints of the aircraft model. These adjustments included modifying the lateral attitude control parameters to achieve the desired damping factors and time constants, ensuring flight quality standards according to MIL-8785C. Validation under real conditions through a flight simulator confirmed the control system’s effectiveness under various operational conditions. The controllers are able to maintain the aircraft’s alignment with the runway centerline, even in the presence of external disturbances, thus demonstrating the system’s robustness and reliability. The methodologies and results provide a solid foundation for future improvements and comparative analyses of autopilot systems within CAT III C requirements.

Virtual reality application in pilotage training: a comparative analysis of real flights

2024-12-03T18:29:18+02:00

Virtual reality technology has been in a development trend since 1966 when it was used as a flight simulator. Since this technology emerged as a training area, has been used in the public sector for 25 years. According to the purpose of study, three main flight stages are determined. These are take-off stage, controlling air movements in traffic pattern, approach and landing stage. External and internal controls, engine start, taxi and take-off tasks are analysed under take-off stage. Climb, ascending, and cruise flight, low and normal bank turns, turns in climb and descent, speed altitude tracking tasks are analysed under controlling air movements in traffic pattern. Triangulation tracking, approach pattern, landing, and leaving the runway, taxiing tasks are analysed under approach and landing stage. Forty one pilotage students are analysed, and the findings showed a statistical difference between VR and real flight performances in Speed Altitude Tracking, Approach Pattern tasks that real flight scores were relatively higher. Additionally, a statistical difference was found between VR and Real Flight Performances related to Approach and Landing stage different from two other stages. To summarize, a significant similarity in terms of grades between VR and real flight experience was found excluding two tasks.

Turbofan engine health status prediction with artificial neural network

2024-12-03T18:29:17+02:00

The main purpose of this study is to present the concept of the aircraft turbofan engine health status prediction with artificial neural network augmentation process. The main idea of engine health status prediction is based on the engine health status parameter broadly used in the aviation industry as well as propulsion technology being the performance and safety margin. As a result of research engine health status index is calculated in order to determine the engine degradation level. The calculated parameter is then used as a response parameter for the machine learning algorithm. The case study is based on the artificial neural network which was two-layer feedforward network with sigmoid hidden neurons and linear output neurons. Network performance is evaluated using mean squared error and regression analysis. The final results are analyzed using visualization plots such as regression fit plot and histogram of errors. The greatest achievement of this elaboration is the presentation of how the entire process of engine status prediction might be augmented with the use of an artificial neural network. What is the greatest scientific contribution of the article is the fact that there are no scientific studies available, which are based on the engine real-life operating data.

Effect of daytime and nighttime on helicopter pilot’s gaze behavior: a preliminary study in real flight conditions

2024-12-04T18:29:18+02:00

Nighttime affects pilot visual scan patterns and increase the risks of helicopter operations, contributing to many helicopter accidents and incidents. Several past studies have attempted to examine the effect of nighttime on helicopter pilot gaze behavior, but researchers had limited success due to the difficulty of collecting representative data under real flight conditions. The present study attempted to address this challenge by conducting a real flight study involving daytime and nighttime traffic pattern tasks and using a Tobii Glasses 3 eye-tracking device to collect helicopter pilot eye-tracking data. This study preliminarily explored the feasibility of data collection in real flight conditions in the context of eye-tracking research on civil helicopter pilots in China. Due to safety considerations, only one pilot was recruited to collect data in multiple tasks. Differences and correlations were examined for all gaze behavior metrics. The results suggested that pilot gaze behavior metrics and their correlations differed between daytime and nighttime flights in aspects critical to aviation safety. Pilot gaze behavior also varied with the flight phase. The findings from this study serve as a reference for optimizing helicopter pilot training systems, improving pilot performance during nighttime flights, and ensuring flight safety on helicopters.

Design study of a Martian rotor blade using a triangular airfoil

2024-12-13T18:29:28+02:00

The Martian atmosphere is characterized by a low density and low speed of sound, which result in the low Reynolds number compressible flows. In this regime, conventional airfoils perform poorly due to the boundary layer separation and the formation of shack wave. The current paper investigates the hovering performance and the structure analysis of a Martian rotor blade built with a triangular airfoil using numerical analysis. The airfoil, with a thickness-chord ratio of t / c = 5% at 30% chord, has been shown through experiments to exhibit non-linear lift enhancement due to the roll-up vortex caused by the sharp leading edge at high angles of attack. The designed blade has a pitch axis of 40% chord, close to the airfoil center of gravity. In order to evaluate the blade thickness distribution along the radial station, Carbon Fiber, due to its high strength-to-weight ratio is applied to the blade. It is found that the main source of stress is inertia force rather than aerodynamic loads and that the blade is structurally safe. Finally, the blade reaches a Figure of Merit of FM = 0.73 at the collective pitch angle of 8 deg and the minimum tensile and compressive factor of safety of 2.90 and 1.74 respectively.

Effect of rolling texture on bearing capacity of aircraft repair patches and replaced panels

2024-12-16T18:29:31+02:00

The article combines issues related to biaxial fatigue loading, corrections for equivalent stress calculations, and the practical application of new knowledge regarding biaxial fatigue in the aviation industry. It considers the possibility and expediency of taking into account the anisotropy of metals’ mechanical characteristics in aircraft repair procedures, such as patching and replacing damaged skin panels. The biaxial loading of the skin is shown to be a significant factor that should be considered in the aircraft skin repair process. It is shown that while well-known Huber-Mises formula works well for isotropic materials, the fuselage skin made of anisotropic alloys requires corrections to the Huber-Mises method. For aircraft parts subjected to biaxial loading, the assessment of equivalent uniaxial stresses can be done by introducing the crystallographic factor into the Huber-Mises formula. This is achieved by transforming the biaxial stress components of fuselage loading due to pressurization and bending into the resolved stresses in the activated crystallographic slip systems of the dominant texture.

Aerodynamic investigation by experimental and computational simulation of a flying wing unmanned aerial vehicle for cargo delivery and surveillance missions

2024-12-16T18:29:31+02:00

Baseline-IX is a tailless aircraft design with compound wing attached to a short body, a transition between a straight, swept flying wing design and a blended wing-body. Baseline-IX planform was designed to deal with a small BWB UAV that is capable of cargo delivery and surveillance missions. The design is influenced by the requirement of cargo space to carry batteries medical and other emergency supplies in its fuselage with a nose-mounted mission camera with a wingspan under 2.0 meters. This paper focuses on studying the aerodynamic characteristics of the novel Baseline-IX, inspired by its predecessor, the Baseline-V. Aerodynamic characteristics of Baseline-IX were investigated and validated through numerical computational simulations and wind tunnel experiments. The maximum lift-to-drag ratio of Baseline-IX obtained through this study is 15.14 for 1:2.4 scaled model and 17.46 for 1:1 prototype. Numerical simulation and wind tunnel experiments’ lift-to-drag ratio percentage difference is 4.92%. Baseline-IX’s lift-to-drag ratio surpasses 14.09% and 24.28% over similar-missions UAV operating in the market while both are larger in size. Baseline-IX has the potential to be developed as a small, easy to carry cargo delivery and surveillance BWB UAV.

Enhancing UAS safety through building-induced dangerous zones prediction: concept and simulations

2024-12-19T18:29:35+02:00

This study presents a comprehensive approach to operational estimation of the zones of danger for the Unmanned Aerial Systems (UASs) generated at low altitudes in presence of buildings, aimed at ensuring their safer operation. The main tasks are three. The first one is the definition of an inboard measurement methodology appropriate and feasible for UAS that allows Eddy Dissipation Rate (EDR) estimation. An inboard setup with a lightweight and low-cost anemometer operating at a 1 Hz sampling rate, immediately usable on UAS, is proposed. The second one is the definition of empirical equations to estimate the size of dangerous areas for the UAS flights around buildings through numerical simulation. The third one is the validation of the empirical formulas in a real-world case, through the numerical simulation of a group of buildings belonging to a research centre. Results show a good resemblance in the size of the danger zones, highlighting that this multi-faceted approach contributes to enhanced safety protocols for UASs operating in urban environments.

Topology optimization methods for morphing aircraft design: a review

2024-12-19T18:29:35+02:00

Current aeronautical research efforts are increasingly focused on weight reduction and the integration of advanced materials analysing dynamic properties. These efforts encompass cellular structures, flexible skins, and modifiable primary and secondary structural elements (e.g., wings). The development of technologies for morphing aircraft design enhances aerodynamic performance and structural efficiency, thereby optimizing the mechanical design of these systems. The authors provide a comprehensive review of the current state of topology optimization methods in morphing aircraft design, highlighting the number of publications in this field and identifying the key journals contributing to this research. It also offers an in-depth analysis of the Solid Isotropic Material with Penalization (SIMP) method, the Evolutionary Structural Optimization (ESO), Bidirectional Evolutionary Structural Optimization (BESO), the recent Proportional Topology Optimization (PTO) and evaluates their effectiveness in achieving efficient designs. Additionally, the review discusses of future challenges and potential advancements in topology optimization for morphing aircraft, offering a thorough overview of the field.