The static coefficient of friction was calculated on an inclined plane tribological stand. Different specimens and masses loading the system were used during the experiment. Surface-to-surface contact was tested in a pin-on-plate setup. The tested polymer pairs were POM on POM, PA6 on PA6 and PET on PET. The variables in the experiment were different pressures acting on the friction pair, and dry and lubricated friction was tested. Static coefficients of friction for each case was calculated and the surface quality of the pin and plate was measured by profilometer and optical microscope. The coefficient of static friction was higher for lubrication friction than the dry friction. It was also observed that the coefficient of friction decreases with increased load. POM – POM pair had the lowest coefficient of friction under dry conditions, while for lubricated friction, PA6 – PA6 had the most stable increase of friction coefficient.

Authors aim to analyze the requirements for the use of simulation technologies for the Air Traffic Pilot License Theory and, based on the selected, measured, and interpreted parameters, to compare the platforms used by the Czech Air Force. At the University of Defence, the simulation center is used as a support instrument. The objective of this paper is to determine the most appropriate flying platform for student-pilots when employing basic radionavigation theory. To verify the analysis, simulated student flights were carried out. The first group of approaches was performed on the simulated platform of the Zlin Z142 aircraft, and the second group on the L39 Albatros aircraft. Individual flights were statistically evaluated and compared. The parameters for comparison were the deviation of the flight altitude compared to the recommended approach altitude and the deviation of the heading compared to the final approach course. Statistical evaluation of the performed simulated flights was made by F-test and verified confirmed that to teach the theoretical subject of Radionavigation, a slower-flying Zlin Z-142 is more suitable. According to the results, the Z142 platform gives the student more time to observe a pilotage error and correct it before starting the final approach phase.

The paper presents tribological tests of selected materials used as liners in a composite hydraulic cylinder. Three coating materials were used for the analysis: Sika F180 polyurethane, Huntsman Araldite LY1564 with Aradur 3487 amine hardener and Bezlona 1111 Super Metal. In addition, uncoated carbon epoxy laminate (CFRP) samples were used as reference material. The instantaneous course of the friction force, its maximum and average value, were the analysed parameters. Ball-on-disk tests were performed on a specialised tester that allows, among other things, to control the operating conditions (clamping force, operating temperature, speed, friction path) and measurement of the instantaneous value of the friction force. After these tests, the friction paths were observed using a Leica DCM8 contactless profilometer with an EPI 20x lens. The amount of energy dissipated due to friction was also determined. The conducted tests and comparative analyses allowed to conclude that the F180 material is the most desirable in terms of tribological properties.

Because the Polish Air Force currently uses F-16 and MiG-29 aircraft, the aim of the study was to conduct a comparison of the susceptibility to destruction in combat of these two aircraft. The first part of the work concerned the analysis of individual critical components, such as: general characteristics of the airframe structure, aircraft engine, flight control system, fuel system, aircraft weapons, radar system. The index of susceptibility to destruction in combat was defined considering the listed critical components and the following types of enemy weapon: aircraft gun, air-to-air missile, anti-aircraft gun, surface-to-air missile. The analysis proved that the aircraft have similar susceptibility to damage in combat, a slight advantage of the F-16 aircraft in this respect was determined. The presented scheme can be used to analyze other aircraft. Proposals of aircraft modifications, directions of further actions, possibilities of using the described method were presented. The method can be used to making decisions by governments regarding the purchase aircraft for their fleets and identify aircraft critical components with high susceptibility to destruction in order to introduce appropriate modifications by military aircraft manufacturers.

This study aims to provide insights into the impact levels of digitalization and intelligentization on air transport system (ATS) in Australia, China, the US, and India. Air transport system is one of the most efficient transport systems which contains three elements: air traffic control, airport, and airlines. In modern society, the importance of digitalization and intelligentization in ATS is attached to by publics. In this study, firstly, comparative analysis is used to analyze the different states of digitalization and intelligentization level and air transport system in sample countries. Then, correlation analysis is used to study the correlation of the different impact factors with the ATS in different countries. The third one is regression analysis, it is used to analyze the relationship between ATS and the development of digitalization and intelligentization in four sample countries. At last, forecasting analysis is used to predict the future trend of digitalization and intelligentization’s impact on ATS in the sample countries in the next few years. Then, the most significant impact factors for ATS will be obtained. Also, the future development trends of ATS under digitalization and intelligentization’s impact could be forecasted by using econometric models.

Vertical flight performance of Lighter-than-Air free hot-air balloons is derived and discussed. Novel mathematical model using lumped-parameters has been used to model balloon flight dynamics and steady-state performance in particular. Thermal model was not treated as the super-heat is under the control of aeronauts/pilots. Buoyancy or gross lift, net or effective lift, specific lift, and excess specific lift were derived for a general single envelope balloon and can be applied to hot-air, gas and hybrid balloons. Rate-of-climb, absolute ceiling, rate-of-descent, and the maximum rate-of-descent or the uncontrolled terminal descent have all been modeled and sample computations performed for AX8 or AX9 FAI-class hot-air balloons. Lifting index or the specific net/effective lift have been computed treating ambient and hot air as ideal gases at various pressure altitudes and representative envelope temperatures. Drag coefficient in upward and downward vertical flights have been chosen based on best available data. Experimental scale and full-scale flight tests are suggested for more accurate estimates of external aerodynamics in vertical balloon flights. CFD computations of coupled inner- and external-flows are also recommended in future efforts. Knowledge of free balloon’s vertical performance is essential in flight planning and operational safety of flight.

In this study, the three-dimensional optimal trajectory planning of an unmanned fixed-wing aerial vehicle was investigated for Terrain Following – Terrain Avoidance (TF-TA) purposes using the Direct Collocation method. For this purpose, firstly, the appropriate equations representing the translational movement of the aircraft were described. The three-dimensional optimal trajectory planning of the flying vehicle was formulated in the TF-TA manoeuvre as an optimal control problem. The terrain profile, as the main allowable height constraint was modelled using the Fractal Generation Method. The resulting optimal control problem was discretized by applying the Direct Collocation numerical technique and then, was transformed into a Nonlinear Programming Problem (NLP). The efficacy of the proposed method was demonstrated by extensive simulations, and it was particularly verified that the purposed approach can produce a solution satisfying almost all the performance and environmental constraints encountering in a low -altitude flight.

As long as people and freights need to move from one place to another, the civil aviation industry will always exist. In this study, a country-based examination has been made on total airfreight transport. Also, gross domestic product (GDP) and total population data were included in this study. 50 countries were selected according to the most recent value that included the years 2018 or 2019 and 26 of these were included in the analysis which was covered in all three rankings. The purpose of the study is to find the similarities between countries based on the total airfreight transportation, total GDP, and total population. The relationship between the three parameters was examined with the correlation analysis. Afterward, the associated parameters were taken as independent variables and the total airfreight transportation variable was modeled by multiple linear regression analysis. In light of these analyses, GDP and total population have a significant impact on total airfreight transportation. To check the assumptions related to outliers, residuals are determined. To show the outliers and the similarities of the countries clearly, the multidimensional scaling method is used. Multidimensional scaling configuration shows that Turkey and the United Kingdom have similarities in terms of total airfreight numbers.

This paper discusses the development of a ground based variable stability flight simulator. The simulator is designed to meet the pilot training requirements on flying qualities. Such a requirement arose from a premier Flight-Testing School of the Indian Air Force. The simulator also provides a platform for researchers and aerospace students to understand aircraft dynamics, conduct studies on aircraft configuration design, flight mechanics, guidance & control and to evaluate autonomous navigation algorithms. The aircraft model is built using open source data. The simulator is strengthened with optimization techniques to configure variable aircraft stability and control characteristics to fly and evaluate the various aspects of flying qualities. The methodology is evaluated through a series of engineer and pilot-in-the-loop simulations for varying aircraft stability conditions. The tasks chosen are the proven CAT A HUD tracking tasks. The simulator is also reconfigurable to host an augmented fighter aircraft that can be evaluated by the test pilot team for the functional integrity as a fly-through model.

In line with the advancing airway capability, the non-aeronautical business opportunities at airports are also in growth. To attract more passengers or to generate extra income over non-aeronautical services, the airport decision-makers need to evaluate the quality of their services. This study aims at introducing an expanded approach to improve airport service quality aspects of the non-aeronautical business opportunities. Given the increasing number of airports, passengers prefer airports, which provide better or extra services compared to others. To reveal the airport service quality (ASQ) aspects, together with the quality department experts, we conducted a qualitative study that put forward six significant dimensions for an effective evaluation of airport service quality at an airport. Based on the results of the qualitative study, we designed the sector-specific questionnaire, and its empirical data is conducted over 250 passengers through a face-toface survey. Survey results introduce a practical assessment tool for the use of airport managers to gather strategic inputs on their strategic plans and quality implications. Results also contribute to the literature by presenting a comprehensive understanding of the airport service quality.