This study examines key indicators and criteria for assessing the efficiency of hybrid turbo-electric propulsion system (HTEPS) configurations for passenger aircraft. A comprehensive review of scientific and technical literature was conducted to identify the most relevant efficiency metrics for HTEPS, with a focus on hybrid-electric propulsion and fuel cell integration. The Evektor EV-55 Outback light multipurpose aircraft, known for its short takeoff and landing capabilities, was selected as a reference model. The study highlights the advantages of all-electric propulsion for a nine-seater aircraft, discussing the impact of hybridization on fuel efficiency, performance, and cost-effectiveness. Two hybridization architectures—sequential and parallel—are evaluated, with the sequential architecture deemed more suitable for small aircraft due to its simplicity and feasibility. The findings confirm that utilizing an engine with lower rated power, in combination with a hybrid-electric system, is a more efficient and cost-effective approach compared to conventional higher-powered engines. The paper concludes with recommendations for optimizing HTEPS configurations and future research directions in hybrid-electric aviation.
The rapid expansion of urban air mobility (UAM) is transforming the market of short-distance transportation, offering a sustainable alternative to ground-based transit systems. The first part of this paper analyzes various propulsion system layouts and aircraft configurations that have been proposed for air taxis, emphasizing their applicability in both passenger and cargo transport. A comprehensive review of existing eVTOL (electric vertical take-off and landing) designs is conducted, highlighting the advantages and limitations of hybrid-electric and hydrogen-based propulsion systems. The study explores the integration of new aerodynamic schemes, such as tiltrotors and flying wings, with advanced energy management strategies to enhance efficiency and flight range. Next, in the second part of this paper, a hydrogen-powered vertical take-off and landing (HydVTOL) aircraft concept, named XFlight, is proposed, in two transport options. The first has a hydrogen-electric power plant inside the body, while the second option has it outside the body. The XFlight design aims to offer greater flight range, higher cruise speeds, enhanced system redundancy, and zero harmful emissions, making it a more efficient and environmentally friendly alternative to current VTOL and eVTOL solutions. The findings underscore the potential of hydrogen propulsion in shaping the next generation of UAM vehicles, offering a pathway to greater autonomy, cost-effectiveness, and scalability in urban transportation networks.
This review paper traces the history of the development of Yugoslav aviation with a particular focus on Mostar, a key center of aircraft production and military aviation research. From the establishment of the Kingdom of Serbs, Croats, and Slovenes in 1918 to the dissolution of Yugoslavia in the 1990s, aviation played a critical role in national defense and technological advancement. During World War II, the Yugoslav Royal Air Force faced overwhelming challenges, while partisan aviation efforts laid the foundation for a post-war military air force. The rapid industrialization of the socialist era led to the rise of the SOKO aircraft factory in Mostar, which – through a productive synergy that emerged between industrial and academic centers – became the cornerstone of Yugoslav aerospace production, manufacturing military aircraft and helicopters, and developing ambitious projects such as the Novi Avion supersonic fighter. However, the breakup of Yugoslavia and the subsequent conflicts led to the collapse of the aviation industry in Mostar, with its infrastructure largely destroyed or abandoned. In the decades that followed, successor states turned to foreign aircraft procurement, while Mostar’s aviation legacy faded into history. This study examines the wartime and post-war evolution of Yugoslav aviation, the pivotal role of Mostar in aircraft production, and the ultimate decline of the country’s aerospace ambitions. It also pays homage to the many professors, assistants and engineers who participated in the discussed projects.
Although the COVID-19 crisis reduced the total number of people suffering from aviation noise, along with significant noise reduction achieved through the effective implementation of the ICAO Balanced Approach, aviation noise continues to be a sensitive environmental factor for local communities. Developing a comprehensive management strategy requires realistic input data for accurate noise modeling and management. This study explores the integration of ADS-B data to improve aviation noise management and multicriteria optimization. The maximum entropy approach is applied to incorporate environmental and operational interrelationships, including noise criteria from various sources. This proposed methodology presents a holistic approach that unites aviation noise modeling, monitoring/measuring, and management to identify and substantiate the best noise reduction practices for a specific airport. The study specifically examines the sensitivity of noise modeling results to realistic flight tracks (ADS-B data) for urban airports in Ukraine, focusing on both lateral (approach and departure stages) and vertical dispersion. Test cases are outlined to demonstrate the efficiency of the entropy-based optimization model.
Piston aircraft engines have undergone significant transformations over the decades, reaching their peak in the 1940s before gradually being replaced by turbine propulsion. Their development has been influenced by technological advancements, fuel composition improvements, and the demands of major armed conflicts, which have accelerated innovation. This study categorizes the historical development of piston aircraft engines into several distinct periods, analyzing changes in operational indicators using data from hundreds of engines (collected through an extensive review of archival publications and manufacturer catalogs). Key factors such as supercharging technologies and fuel quality are examined to highlight their impact on engine performance. Given the broad scope of the subject, this article focuses on the era when piston engines dominated aircraft propulsion, illustrating their advancements through comparative analysis and graphical representations of power, efficiency, and design trends.
ABSTRACT This paper explores strategies for extending the operational lifespan of flame tubes in turbofan engines – a critical component for maintaining engine efficiency and reliability, in line with global trends aimed at maximizing the use of laid reserves of aircraft engine performance. Utilizing a combination of advanced computational simulations and empirical research, the study meticulously analyzes the internal processes within the flame tube of the AL-31F turbofan engine. A detailed geometric model and finite element grid were created and adapted to simulate various operating conditions and assess their impact on the flame tube’s performance. Special attention is given to understanding the thermal and mechanical stresses that influence its durability and serviceability. The results, compared against experimental data, validate the simulations and are crucial for identifying critical sections prone to damage, thereby facilitating enhanced decision-making regarding maintenance schedules and overhaul practices. This approach not only aims to minimize downtime and reduce maintenance costs but also extends the service intervals for critical engine components, thereby improving thermocyclic durability based on the damage mechanisms identified.
ABSTRACT Monitoring corrosion in aircraft structures through nondestructive testing is crucial for maintaining long-term aircraft serviceability. Corrosion monitoring is particularly challenging when corrosion damage is situated on internal surfaces of multilayer aircraft structures. The eddy current method is one of the most promising techniques for detecting and measuring such subsurface corrosion damage without direct contact or disassembly. However, due to their low sensitivity traditional eddy current probes with coaxial coils are not well suited for detecting corrosion damages of the local type, such as pitting or corrosion pits, in multilayer aircraft structures. This study tested the use of low-frequency eddy current probes of the double-differential type, characterized by 8 and 10 mm operational diameters, in detecting and measuring hidden corrosion damages of this local type. Such corrosion damages were simulated by means of flat-bottomed drilled holes of differing diameters and depths (or different diameters and residual thicknesses of the inspected sheet in the damaged area). The signals from the eddy current probes were evaluated in the complex plane using a universal eddy current flaw detector. The correlations between the amplitude and phase of the eddy current signal and depth of location of the local corrosion damages were analyzed. Results indicate that it is possible to estimate the residual thickness of the skin in locally corroded areas by measuring the eddy current signal phase, independently of the local corrosion damage diameter (size), providing useful information for residual service life determination.
ABSTRACT Eddy current array (ECA) technology is increasingly being used in the aerospace industry for non-destructive testing of aircraft components. This study evaluates the performance of ECA in detecting defects in aircraft components, focusing on its effectiveness, reliability, and sensitivity. The study evaluates the effectiveness of ECA technology in eddy current defectoscopy by introducing a dimensionless efficiency coefficient, then seeks to validate this coefficient through experimental testing of aircraft component materials with artificially induced defects of various sizes, types, and orientations to simulate real-world scenarios. ECA’s sensitivity in detecting small and subsurface defects is analyzed, along with precise defect sizing and positional information. Reliability and repeatability are investigated through repeated measurements. Furthermore, the article analyses the impact of various factors on the performance of ECA, including surface conditions, probe configurations, and inspection parameters. Comparative analysis is performed to assess the advantages and limitations of ECA in comparison to other conventional inspection methods. The findings of this study will contribute to a better understanding of the capabilities and limitations of ECA in detecting aircraft component defects. The results will aid in optimizing inspection strategies, enhancing the reliability of defect detection, and improving the overall maintenance practices in the aerospace industry.
This paper addresses the persistent challenges in speech processing within the Air Traffic Control (ATC) domain, a field where despite extensive research, issues such as handling noisy environments, accented speech, and the need for strict adherence to standard phraseology continue to undermine conventional language models. Our study employs a hybrid approach that integrates syntactic analysis with advanced machine learning classification algorithms – Logistic Regression, Lagrangian Support Vector Machine, and Naïve Bayes. By mixing and matching algorithms tailored for specific aspects of speech processing, our approach moves away from traditional reliance on a singular integrated system, illustrating through rigorous testing with the ATCOSIM dataset that such a multifaceted strategy markedly improves command recognition accuracy and adapts more effectively to the unique linguistic features of ATC speech. Results highlight the superior performance of Logistic Regression across various command recognition categories, pointing towards a promising direction for future advancements in ATC speech recognition technologies aimed at reducing human workload and increasing automation precision. This paper explores the complexities of the required analysis techniques and underscores the necessity of employing diverse algorithms in the processing pipeline to enhance overall system accuracy.
ABSTRACT This paper analyzes approaches to developing models for the technical exploitation (TE) of aircraft within operational management framework. The operational management contour of the TE of the airline’s AC fleet is considered as a TE process consisting of a sequence of flight routes, which, in turn, comprise a sequence of flights between airports in the airline network during the calendar interval when the aircraft are in this contour. We present a model that evaluates the capacity for aircraft recovery at the network airports of a hypothetical airline (dubbed “RAF”) if the need so arises, utilizing the probabilistic and temporal characteristics of the airports used for aircraft recovery.
ABSTRACT This study applies advanced computational fluid dynamics (CFD) simulations to enhance the safety of an aircraft’s fuel system by striving to minimize the risk of on-board fire hazards. Employing a detailed flow simulation model, this research assesses the efficacy of newly designed measures within a fuel system, designed for a modified radial engine on a test-bed AN 2 airplane. The model simulates internal airflow, droplet particle flow, the formation of Eulerian Wall Film, and the vaporization process from the fuel film within the enclosure of the aircraft’s equipment bay. By exploring both the original and modified geometries of this fuel system enclosure, the simulations provide insights into the flowpaths of leaking fuel, the spatial and temporal distribution of fuel vapor concentrations, and the overall effectiveness of design modifications aimed at rapid removal of hazardous substances. Structural improvements, including the addition of strategic ventilation inlets and outlets, are proposed based on the simulation results to ensure rapid dispersion of vapors and minimal residual fuel, effectively reducing the potential for vapor ignition. This study thus underscores the potential of precise CFD modelling in identifying risks and developing robust fire hazard mitigation strategies in aviation fuel systems.
ABSTRACT This paper introduces non-destructive testing (NDT) techniques centered on measuring magnetic properties, offering insight into evaluating structural steels throughout aircraft production and service life. It highlights the method’s utility in quality control of steel components, particularly in detecting variations in microstructure affecting mechanical properties. The NDT method correlates material structural state with magnetic properties, utilizing parameters such as coercive force, remanence, and hysteresis loop area. Developed instruments, like the MA-05 Magnetic Analyzer and KRM-Ts coercive force meter, enable precise measurements in both closed and open magnetic circuits. Applications range from assessing heat treatment quality to monitoring materials degradation in challenging conditions. A set of 12 gas containers that have been in service in aircraft for more than 40 years are tested as a case study, demonstrating the method's efficacy in evaluating damage accumulation. Future prospects include other potential applications in testing aircraft landing gear components.
ABSTRACT Recent challenges in space access include cost optimization and space debris reduction. The European Space Agency has envisioned the evolution of in-orbit transportation involving re-usable service vehicles, moving payloads from high parking orbits to their target orbits. This concept for orbital infrastructure requires de-risking activities and the development of building blocks, such as standardized interfaces and communication. Mastery of close-proximity operations and docking is essential for the new transportation system. This new branch of space operations represents a good opportunity to introduce more sustainable propulsion solutions, especially given the high costs and uncertain future of hydrazine and its derivatives. IOSHEX, a service spacecraft to be equipped with a green propulsion system utilizing 98% hydrogen peroxide, serves as a reference. This paper presents a design concept for this propulsion system, including trade-off analyses, calculations, and a three-dimensional model integrated with IOSHEX.
ABSTRACT This study investigates the drag coefficient of three models of suborbital rockets with different nosecones. A test section allowing for force measurement of a 1:50 scale rocket model was designed with the aid of numerical simulations. The velocity obtained in the wind tunnel corresponds with a Mach number of 2.45. RANS simulations were used in verifying operating parameters, as well as testing the support configurations for connecting the model with the bottom wall of the tunnel section. Pressure distribution measurements on the top and bottom walls of the wind tunnel matched simulation results well. The shock structure in the test section was visualized using the schlieren technique, revealing that the measured angle of the main shock generated at the tip of the rocket matched the simulation data. Finally, the measured forces were compared with simulations for one of the nosecone configurations. Despite very good agreement for pressure distribution on the wind tunnel walls and shock structure, a significant mismatch in the forces measured was nevertheless observed: the simulated CD (0.57) being four times larger than that obtained in measurements (0.138). Further analysis of the test section is required to pinpoint the source of discrepancies and redesign the force measurement system to achieve improved force results.
ABSTRACT This paper explores the influence of engine modernization on the dynamic stability and performance of a general aviation aircraft. Utilizing an integral mathematical model, the study conducts a comparative analysis of the I-23 Manager piston-engine aircraft and its modified I-31T turboprop version, examining changes in aircraft dynamics depending on the power plant type. The modernization necessitated a redesign of the nose section of the fuselage, resulting in alterations to the external shape and flight properties of the aircraft. The research evaluates various dynamic stability parameters, including phugoid, short period, Dutch roll, roll, and spiral modes, under different flight conditions. Results indicate minimal changes in aerodynamic characteristics due to the engine type, yet significant improvements are observed in efficiency, noise reduction, and operational costs. The impact of the propulsion unit on the dynamic stability of the light aircraft was assessed as insignificant, suggesting that the strategy of modernizing an existing piston-driven aircraft by switching to a turboprop drive is indeed promising. With appropriate initial design assumptions, a modern turbine aircraft with strong flight qualities can be efficiently modernized in this way, without compromising the good flying properties of the existing plane. The outcomes are validated against flight tests, reinforcing the viability of integrating more sustainable and efficient propulsion systems into light aircraft. This study may therefore inform future design and regulatory decisions, providing a perspective on the implications of engine upgrades in the general aviation sector.
ABSTRACT Aluminum alloys (AAs) are pivotal materials in modern aircraft due to their superior mechanical properties and low weight. The structural integrity of these alloys, crucial for aircraft safety, heavily depends on heat treatment processes that alter their mechanical characteristics. Nondestructive evaluation (NDE) techniques, such as eddy current (EC) conductivity measurements, play a vital role in assessing these alloys throughout their lifecycle. EC methods enable the measurement of electrical conductivity, a structure-sensitive parameter that correlates with mechanical properties affected by heat treatments and operational stresses. This paper reviews the application of EC conductivity measurements in the aerospace industry, focusing on their role in assessing AA structural integrity. It discusses how EC methods can penetrate non-conductive coatings, crucial for in-service measurements without surface removal. Recent developments include a novel small-size EC probe and signal processing algorithms aimed at enhancing sensitivity to conductivity changes through dielectric coatings, up to 0.5 mm thick, commonly found in aircraft structures. Key findings include analyses of specific electrical conductivity (SEC) changes in AAs due to heat treatment deviations and long-term operational stresses, crucial for predicting residual life and maintaining safety standards. Case studies on aircraft wing skins and helicopter rotor blades demonstrate the practical application of EC conductivity meters in identifying critical damage zones. The methodology proves effective in evaluating localized degradation based on SEC distributions, thereby enhancing maintenance efficiency and aircraft safety. Overall, this research underscores the significance of EC conductivity measurements in advancing NDE practices for AAs in aircraft applications. The methodologies and findings presented aim to improve safety, durability assessment, and maintenance efficiency in the aerospace industry.
ABSTRACT This study proposes a probabilistic model to assess the likelihood of passenger survival in fires resulting from aircraft accidents. The model evaluates the risk of passenger death in a fire, considering the type of aircraft and airline. By comparing the time available for passengers to fully evacuate a burning plane with the time required for evacuation using modern means and technologies, onboard rescue equipment, and the qualifications of crew members and rescue personnel, we introduce a comprehensive approach to quantify passenger survival rates. Additionally, the concept of the hazard coefficient is introduced, which accounts for factors such as cabin temperature and toxic components.
ABSTRACT This article presents the results of the analysis of approaches to designing a mobile vacuum system ‘METAMORPHOSIS’ for simulation of space environment, which could help provide services of testing space objects at the request of the customers at a place and time acceptable to them, which allows saving time and assets in the development of space objects, their elements, including satellites. As a result of the conducted analysis, methodological approaches to the determination of the structure of the vacuum system were undertaken. To avoid unanticipated issues and to validate computer-driven modelling, testing in a space simulation chamber is an important part of the quality-assurance process. Spacecraft and their components must withstand extreme temperatures and pressure to travel outside the Earth’s atmosphere. Space simulation testing involves the use of a thermal vacuum chamber to replicate the conditions experienced in space.
ABSTRACT This paper considers the comparative analysis of the physical and mathematical methods of the optimal operation of aviation objects’ automatic control systems, which is an urgent scientific and technical task. The paper also represents the corresponding stability criteria, depending on the operating conditions, and the influence of external factors that allows ensuring the automatic control systems’ reliable operation not only in normal circumstances, but also in the presence of probable disagreements. The scientific novelty of the research lies in developing new stability criteria by means of synthesising the influence of different factors and also the ability to ensure optimal functioning of the automatic control systems. Corresponding mathematical and computer models have been developed. The use of these models allows to determine the optimal stability criteria for control systems with parameters of a different physical nature and ensure reliable operation of electromechanical systems for general and special applications based on the current analysis. The research results are illustrated by corresponding mathematical models, engineering calculations and modelling of the optimal control limits depending on the influence of various factors. The simulation results coincide with the theoretical calculations, which indicates the consistency between the microprocessor-based and software of automatic control systems.
ABSTRACT The article describes the problem of controlling an aircraft control when performing a landing on a curvilinear trajectory. The adoption of a curvilinear approach trajectory allows reducing the impact of air traffic on the areas adjacent to the airport. Performing the correct approach on the curvilinear path requires support. For the correct execution of the landing manoeuvre on the curvilinear track, it is necessary to establish reference points so that the repeatability of the manoeuvre is ensured, especially in the case of landing more than one aircraft at the same time. In the following parts, the landing control system is presented. Particularly carefully presented is the issue of performing tests of the designed control system, which in the case of the aircraft control system during the approach to landing must be extremely thoroughly verified. The test plan included both verification the correctness of the adopted control laws and their robustness to interference occurring as a result of atmospheric air streams.
