Abstract: The most common solutions for rocket engines are the single operation point (thrust level) units. Oxidiser and fuel mass flow rates and the oxidiser-to-fuel mass flow rate ratio (OFR) are some of the determinants of the thrust level. Based on these, planetary ascent and descent; space rendezvous; orbital manoeuvring, including orientation and stabilisation in space; hovering, hazard avoidance during planetary landing; and ballistic missile trajectory control propulsion systems could use throttleable liquid engines. Several engine throttling methods, such as supply pressure variation and variable injector area, can be applied. Among others, a cavitating venturi propellant regulatory valve is one of the most promising throttling method. This type of valve can provide steady mass flow, despite the downstream pressure disturbance (i.e. from the combustion chamber), which sustains a stable engine thrust as the mass flow is kept. The article presents the valve sizing method, design and prototype test results of the cavitating venturi valve that has potential for utilisation in a deep throttling rocket engine. Mass flow stability and repeatability are presented for valve operating points in the 10%–110% nominal mass flow range. Valve design optimisation, based on CFD, to sustain cavitation for a higher downstream-to-upstream pressure ratio is shown. PubDate: Wed, 13 Sep 2023 00:00:00 GMT
Abstract: Satellites are used for navigation, communication, oceanography, astronomy, etc.. Satellites come in a diversity of sizes and forms. Depending on the satellite’s mission, different subsystems are used. These subsystems are installed inside a housing to protect them from the space environment. This housing, which is also known as the satellite primary structure or mechanical structure, is made of durable materials that can endure severe conditions during launch and in the orbit. The optimisation of satellite mass is crucial right now since satellites are losing mass every day to reduce the cost of manufacturing and launching. This review first introduces an overview of the satellite classifications and subsystems. Then, the different types of mechanical load analysis the satellite subjects itself to are demonstrated. The advanced approaches for promoting the performance of the mechanical structures of satellites are explored, with a spotlight on the effect of the optimisation parameters of isogrid and honeycomb sandwich structures on the mechanical performance of the satellite primary structure. The assembly, integration and testing (AIT) of the small satellite are briefly presented. Finally, the important potential designs to improve the mechanical performance of the satellite primary structure and the challenges of further research are summarised. PubDate: Wed, 19 Jul 2023 00:00:00 GMT
Abstract: The method for determining the main parameters of the tail cargo doors of transport category aircrafts is developed. A methodology for the ascertainment of these parameters has been described. An example based on an existing transport aircraft is considered. Gathered were information pertaining to the necessary design, operational and regulatory parameters and requirements of the international regulatory organisations Federal Aviation Regulations (FAR), Certification Specification (CS) and Aviation Regulations (AR). The principle of determining the dimensions of the cargo compartment, cargo floor and the hitting platforms, in the form of a ramp with a pressure door and ladders, is presented based on the initial data. Considering the described loading and unloading, as well as landing, operations, the dependence of the ramp length on the length of the cargo floor is ascertained. A method for designing a cargo door fairings in the transport category aircraft fuselage tail part is presented. The main features of the fairings compartment have been determined, together with those of its main components and their varieties, depending on the scheme of the cargo door. Information is provided on the fairings compartment structural elements parameters selection. PubDate: Tue, 18 Jul 2023 00:00:00 GMT
Abstract: The stress distribution function in the surface layer is created as a result of using stress measurements on the surfaces of C45 steel samples after shot peening. Stresses were measured by X-ray diffraction with the use of the PSF-3M device from the Rigaku Company. For measuring residual stresses, subsequent layers of the top surface of the material were used as a basis, and these were obtained through electrochemical etching. The test results i.e. distance into the material, sample hardness, shot type, stress) were entered into the stepwise multiple regression program. A record of residual stresses was obtained in the form of the second-degree regression function of three independent variables with interactions. The obtained analytical form of the residual stress function was used in the FUNVAL3.EXE program to calculate the tabular values of stresses permeating into the material. For the analytical description of the stress distribution, the REGPOLY.EXE regression program was used, which creates a polynomial functional form of the residual stress distribution. The plot form of the residual stress distribution was obtained using the EXCEL Microsoft Office 2000 program. PubDate: Tue, 18 Jul 2023 00:00:00 GMT
Abstract: The paper presents the development process of the solid rocket boosters (SRBs) separation system of the ILR-33 AMBER 2K rocket. A redesign of the system was required due to the development of new, larger SRBs. The main system requirements were transmission of forces and moments between the SRBs and the main stage, execution of the separation process at a given moment in flight and mechanical integration simplification. A set of aerodynamics calculations were performed. With the use of computational fluid dynamics software, forces acting on the booster during separation for several angles of attack, as well as the critical booster deflection angle, have been determined. Next, a mathematical model was created to define the load spectrum acting on the system during the flight and separation phases, covering both static and dynamic loads. All the internal and external force sources were considered. A series of motion dynamics simulations were conducted for representative flight cases. Then, the system operational parameters were verified with the use of dedicated ground test facilities. Necessary calibrations of the mathematical model were then implemented, leading to a high level of confidence with the empirical data obtained, thereby leading to a successful system qualification for the flight campaign. PubDate: Tue, 18 Jul 2023 00:00:00 GMT
Abstract: This study investigates whether personal commitment moderates the effect of aerospace education on service experience through quality design. A cross-sectional study using a close-ended questionnaire was administered to a sample of 174 aviation students of Moi University, Kenya. Moderated mediation analyses were conducted using the PROCESS macro in order to investigate the relationship among variables. The results showed that the association between aerospace education and service experience was significant, and this association was mediated by quality design. The mediated effect of quality design was moderated by personal commitment. Based on the findings, companies involved in aviation should focus on improving the good environment of the service encounter (i.e., education, quality design and commitment) to enhance service experience. The findings made a contribution in terms of allowing us to understand the factors that can enhance service experience in the aviation industry. PubDate: Tue, 18 Jul 2023 00:00:00 GMT
Abstract: The study demonstrates the possibilities of using, as well as the features associated with the use of, unmanned aerial vehicles (UAVs) for military and peaceful purposes. Information is provided on the need to use components that would contribute towards ensuring thermal protection against modern laser weapons. The requirements for such materials are given, according to the field of application of the UAV. An analysis of the available materials that can be used to create thermal protection of UAVs against laser weapons is provided. The thermophysical characteristics of various materials are presented. The work presents technological features of production and properties of low-density carbon–carbon composite materials (CCCM). It is proposed to consider the prospects of using CCCM materials for not only the UAV structural components but also other purposes. PubDate: Tue, 06 Jun 2023 00:00:00 GMT
Abstract: The growing use of thermoplastic composites in aviation, automotive, sports and medical industries is forcing the development of processing technology. Due to the properties of thermoplastic composite materials, their shaping is subject to many restrictions. For this reason, it is not always possible to obtain components with complex geometry and adequate quality. By using numerical analysis and experience in the production of parts using hot pressing technology, we are able to predict the course of the process and the behaviour of the material during formation. The article describes how to build a model for numerical analysis of the process of thermoforming monolithic inspection door stiffening for an ILX-34 aircraft using a Toray Cetex® TC1225 carbon composite material with a thermoplastic polyaryletherketone (PAEK) matrix. Pam-Form v2019.0 software version V1.9.N was used for modelling. The results of the analysis were compared with those of the part produced by the Institute of Aviation, Łukasiewicz Research Network. PubDate: Tue, 06 Jun 2023 00:00:00 GMT
Abstract: The article describes methods of creating mechanical parts in 3D programs, together with presenting very significant issues that emerge during the designing process employed in this creation, the main goal being to show the most important factors playing a role in the design process. Resultantly, it is ascertained that the most important factors needing to be considered by a designer are, inter alia, mass of the parts, strength, and kind of material. The article indicates the different types of parts used in different load cases, the objective being to explain various aspects relevant to design. The parts were different in particular in their nature of work and purpose. The article also presents illustrations after finite element method (FEM) analysis. It was important and interesting to observe how the stress in the tested parts was distributed under load and how the structure changed when the used material changed. The stress had a very large influence for the design of every airplane part; a case in point would be the illustration available from the lever example. The main role of this article is to describe different designing factors that could help a specialist create new designs in the future. PubDate: Wed, 05 Apr 2023 00:00:00 GMT
Abstract: This paper proposes a solution to a certain macroeconomic model. A multi-alternative problem of aviation transportation optimal organisation in conditions of uncertainty of the subjective preference functions is considered. Conditional optimisation of the objective functional containing the entropy of the individuals’ operational effectiveness functions preferences is carried out in the framework of the simplest macroeconomic problem. The principle of the Solow and Cobb–Douglas models, likewise for economic growth, is modified with the Subjective Entropy Maximum Principle. The advantages of the described optimisation approach are demonstrated in generalised terms of the operational effectiveness functions for aviation transportation organisation. PubDate: Tue, 04 Apr 2023 00:00:00 GMT
Abstract: In recent years, a significant number of one- and two-seat lightweight helicopters have come into existence, and this makes it possible to analyse parameters and determine dependencies for this class of helicopters. the knowledge of such dependencies is necessary at the preliminary design stage. the analysis performed in this paper and its comparison with the statistical data of all categories of helicopters made it possible to determine the necessary corrections in the methods of determining the parameters of the helicopter’s rotor systems. PubDate: Fri, 17 Mar 2023 00:00:00 GMT
Abstract: Tensile tests were carried out on three series of composite samples according to the ASTM (American Society for testing and Materials). The materials tested were characterised by using the same manufacturing method. The specimens were hand-laminated using MGS L285/H285 epoxy resin. The feature that differentiates the structure of each laminate series is the type of reinforcement. A biaxial fabric IMS65 CtLX with a 0/90 arrangement was used to reinforce the C-series composite specimens; for the D-series, a symmetrical fabric Interglass 02037 with a 0/90 weave was used, and for the E-series specimens, a modular fabric IMS65 with a 45 weave was used. The share of composites in the manufacture of construction products is steadily increasing. This is due to the development of new technologies for manufacturing composite elements and composites, with properties that are more and more in line with the requirements of the industry resulting from technological progress. Composite products have to meet many performance requirements. Tensile testing is used to determine some of the key mechanical properties of laminates. Fibre-reinforced polymer (FRP) composites have been used in various engineering structures for many decades. Their unique physical and mechanical properties make them a well-known, most produced and most widely used type of composite materials. In the case of fibre composites, it is the fibres that take over the basic stresses and are responsible for achieving the appropriate stiffness and strength, while the matrix ensures optimum use of the properties of the fibres and gives shape to the manufactured element. The mechanical properties of the composite and its failure process are fundamentally dependent on the high strength of the fibres, the stiffness of the matrix and the strength of the fibre-matrix interface. PubDate: Fri, 17 Mar 2023 00:00:00 GMT
Abstract: The paper proposes a stand that can be used for the testing of propellers and rotors with diameters up to 2.4 m, whose areas of application encompass, inter alia, vertical takeoff and landing (VTOL) type multi-rotor drone systems. The presented solution allows for testing propellers in systems with electric motors. To a certain extent, it is possible to achieve an increase in the measuring range by changing electric motors, power supply systems and measuring sensors. The paper presents several solutions for test stands that can be applied in the testing of propeller parameters, and commercially available propellers have also been deployed in the testing routines. The paper briefly presents the concept of the stand and its design, as well as the principle of operation and structural calculations underlying its functioning, after which the numerical model of the test stand is explained. The article then demonstrates the particular results of the test stand model’s functioning using the EMRAX 188 electric motor and two propellers, namely a commercial Aerobat propeller and a composite propeller designed and manufactured at the Łukasiewicz – Institute of Aviation. Thus, the paper presents both the theoretical results that follow from the model and the results of experimental research. PubDate: Fri, 17 Mar 2023 00:00:00 GMT
Abstract: Propulsion system operation is known to affect the aerodynamic characteristics of rockets. Specifically, the net axial force acting on a rocket in flight cannot be precisely obtained by combining the static thrust with drag values computed for a rocket with an inactive motor. One of the main reasons for this is the influence of motor operation on pressure at the base of the rocket. The aim of this paper is to investigate the effect of motor operation on the aerodynamic parameters of the Grot sounding rocket developed by the Students’ Space Association, Warsaw University of Technology. The study consists of two series of axisymmetrical computational fluid dynamic simulations of flow around the rocket – one with the motor being non-operational and the other with active thrust. In the post-processing phase, the axial force acting on various components of the rocket is computed, with an emphasis on the base and nozzle exit sections. Quantitative and qualitative differences between the cases with and without active thrust are highlighted and discussed. The obtained results are compared to a semi-empirical model found in the literature. Finally, a semi-empirical base drag model is proposed for use in Grot flight simulation. PubDate: Thu, 16 Mar 2023 00:00:00 GMT
Abstract: A helicopter landing and taking off on an elevated helipad is a source of noise that affects the environment and causes vibrations of the landing pad or the building infrastructure. Vibrations are also excited by the air stream flowing through the main rotor and transferred to the landing pad by contact of the helicopter chassis. Vibrations are transferred to the building through the structure of the helipad. Depending on the damping properties of the structure and the vibro-isolating elements used, vibrations can be felt in rooms used by people and also transmitted to devices located in the building. the subject of the study described in this paper is the vibroacoustic effects of an eC-135 helicopter on an elevated landing pad during landing, standstill with the propulsion system engaged and take-off. Measurements of vibrations and noise were made at points located both on the landing pad and in the building. the paper presents selected results of measurements in various phases of flight and helicopter manoeuvres. the frequency analyses of the fragment of the measurement data for the flight phase, in which the highest levels of impact were recorded, were also performed and included. the results are presented as graphs and annotated. PubDate: Sat, 31 Dec 2022 00:00:00 GMT
Abstract: It is known that during operation, the aircraft construction materials are exposed to significant mechanical loads and changes in temperature for a very short period of time. All this leads to various defects and damages in the aircraft assemblies and units that need to be inspected for the safe operation of the aircraft, their assemblies, and units. In some cases, the implementation of inspection or diagnostic is accompanied by the emergence of technical difficulties caused by the large size of the aircraft assemblies or units and limited access to their local places. Under such conditions, ensuring the possibility of diagnosis in hard-to-reach places of the object becomes especially important. The problem can be solved by applying wireless technologies. It allows spatial separation of the probes and the signal processing units, which simplifies the scanning of the surfaces of the large assemblies and units in hard-to-reach places. In this article, the description of the developed wireless system of eddy current inspection for aircraft structural materials is given. Experimental results of object scanning are given in the form of a distribution of the values of probe signal informative parameters (amplitude, frequency and decrement) along the object coordinates. PubDate: Sat, 31 Dec 2022 00:00:00 GMT
Abstract: Aircraft are equipped with ice protection systems (IPS), to avoid, delay or remove ice accretion. Two widely used technologies are the thermo-pneumatic IPS and the electro-thermal IPS (ETIPS). Thermo-pneumatic IPS requires air extraction from the engine negatively affecting its performances. Moreover, in the context of green aviation, aircraft manufacturers are moving towards hybrid or fully electric aircraft requiring all electric on-board systems. In this work, an ETIPS has been designed and optimised to replace the nacelle pneumatic-thermal system. The aim is to minimise the power consumption while assuring limited or null ice formation and that the surface temperature remains between acceptable bounds to avoid material degradation. The design parameters were the length and heat flux of each heater. Runback ice formations and surface temperature were assessed by means of the in-house developed PoliMIce framework. The optimisation was performed using a genetic algorithm, and the constraints were handled through a linear penalty method. The optimal configuration required 33% less power with respect to the previously installed thermo-pneumatic IPS. Furthermore, engine performance is not affected in the case of the ETIPS. This energy saving resulted in an estimated reduction of specific fuel consumption of 3%, when operating the IPS in anti-icing mode. PubDate: Sat, 31 Dec 2022 00:00:00 GMT
Abstract: This paper proposes a solution to a certain macroeconomic model. A multi-alternative problem of aviation transportation optimal organisation in conditions of uncertainty of the subjective preference functions is considered. Conditional optimisation of the objective functional containing the entropy of the individuals’ operational effectiveness functions preferences is carried out in the framework of the simplest macroeconomic problem. The principle of the Solow and Cobb–Douglas models, similar to the approach adopted for the estimation of economic growth, is modified with the subjective entropy maximum principle. The advantages of the described optimisation approach are demonstrated in the generalised terms of the operational effectiveness functions for aviation transportation organisation. PubDate: Sat, 31 Dec 2022 00:00:00 GMT
Abstract: One of the most perspective directions of aircraft engine development is related to implementing adaptive automatic electronic control systems (ACS). The significant elements of these systems are algorithms of matching of mathematical models to actual performances of the engine. These adaptive models are used directly in control algorithms and are a combination of static and dynamic sub-models. This work considers the dynamic sub-models formation using the Least Square method (LSM) on a base of the engine parameters that are measured in-flight. While implementing this function in the (ACS), the problem of checking the sufficiency of the used information for ensuring the required precision of the model arises. We must do this checking a priori (to determine a set of operation modes, the shape of the engine test impact and volume of recorded information) and a posteriori. Equations of the engine models are considered. Relations are derived that determine the precision of parameters of these models’ estimation depending on the precision of measurement, the composition of the engine power ratings, and durability of observations, at a stepwise change of fuel flow. We present these relations in non-dimensional coordinates that make them universal and ready for application to any turboshaft engine. PubDate: Fri, 16 Dec 2022 00:00:00 GMT
Abstract: The increasing level of urbanisation and traffic congestion promotes the concept of urban air mobility (UAM), which has become a thriving topic in engineering and neighbouring disciplines. the development of a suitable ground-based infrastructure is necessary to supply these innovative vehicles, which mainly includes networks of take-off and landing sites, facilities for maintenance, energy supply, and navigation and communication capabilities. Further requirements comprise robust business and operating models for emerging service providers and regulatory frameworks, particularly regarding safety, liability and noise emissions. the objective of this study is to provide an overview of the current results and developments in the field of UAM ground-based infrastructure by conducting a systematic literature review (SLr) and to identify the most relevant research gaps in the field. For the systematic literature analysis, our search string contains vertiports and the equivalents, UAM and equivalents, and search phrases for the individual domains. In the final analysis 64 articles were included, finding a strong focus on simulations and vertiport networks, while specific case studies and related aspects like automated MrO and urban planning appear less frequently. therefore, this article provides insights for a more holistic perspective on challenges and necessities of future UAM. PubDate: Fri, 16 Dec 2022 00:00:00 GMT
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