The catalogue of observational platforms for space and atmospheric research can be expanded by utilising drones equipped with specialised instrumentation and capable of flying at high altitudes. In this project the requirements for an electric propulsion system applicable to the KTH Royal Institute of Technology ALPHA project are evaluated. A selection of electric motors, propellers and electronic speed controllers are tested to analyse their applicability using two different test setups. The tests include evaluation of propeller characteristics such as thrust and torque generation along with operational angular velocity ranges and the efficiency of brushless DC motors. The results are analysed and extrapolated to approximate the performance in the dynamic environment that the ALPHA aerial vehicle will encounter. From the tested hardware a propeller with a diameter of ten inches and a pitch of seven inches is found to fulfil the requirements. Out of the tested motors, six of them achieve the necessary performance and these are presented with suggestionsfor further analysis. / Mängden observationsplatformar inom rymd och atmosfärisk forskning kan utvidgas genom att använda drönare utrustade med specialicerade instrument som är kapabla att flyga på hög höjd. I detta projekt evalueras kraven på ett elektriskt drivsystem tillämpningsbart p ̊a KTH Royal Institute of Technologys ALPHA projekt. Ett urval av elektriska motorer, propellrar och elektroniska hastighetsregulatorer testas för att analysera deras tillämplighet genom använding av två olika testuppställningar. Testerna inkluderar evaluering av propellrars dragkraft, vridmoment samt operativ spann av vinkelhastighet, men även börstlösa DC motorers effektivitet och prestanda. Resultaten analyseras och extrapoleras för att approximera prestanda i den dynamiska miljön som ALPHA drönaren kommer att möta. Av den testade hårdvaran uppfyller en propeller med en diameter på tio tum och en stigning på sju tum kraven. Av de testade motorerna uppnår sex av dem den prestanda som krävs och dessa presenteras med förslag på vidare analys / Kandidatexjobb i elektroteknik 2022, KTH, Stockholm

This thesis explores the potential of utilizing metal-based plasma sources as a sustainable solution for high-powered electric propulsion and its implications for future interplanetary travel. Focusing on the Vacuum Arc Thruster and the Variable Specific Impulse Magnetoplasma Rocket engine, the study encompasses numerical simulations, analytical comparisons, and performance analyses to assess the feasibility of metal plasma fuels in space missions.The numerical analysis employs COMSOL Multiphysics to delve into the magnetohydrodynamics behavior within the VAT. Such simulation setup could provide valuable insights. Although the numerical results are disappointing for this paper, there exist possibilities within future work. The main hurdle is the simulation of vacuum. There are workarounds in COMSOL's Vacuum System Modeling tool which was not available for this thesis. Also, the used material properties were not suited for this high temperature plasma environment. The lack of material properties is a consequence of the insufficient research in the metal plasma field.Performance analysis is conducted on both the VAT and VASIMR engine, exploring efficiency, thrust capabilities, and feasibility for interplanetary missions. The results demonstrate the potential of metal-based plasma sources to reduce dependence on Earth for refueling and decrease mission costs. It is found that aluminum and magnesium have similar performance as the argon gas used in the VASIMR.Although challenges exist, such as integration problems and availability of material properties for metals in plasma states, the study underscores the promise of metal plasma fuels for sustainable space exploration. By advancing high-powered electric propulsion technologies, we move closer to realizing humanity's ambitious journey to distant celestial bodies. This research paves the way for future innovations, enabling a more self-sustaining space economy and unlocking new horizons of interplanetary travel.

Small unmanned aircraft and electric vertical takeoff and landing (eVTOL) aircraft have recently emerged as vehicles able to perform new missions and stimulate future air transportation methods. This dissertation presents several system identification research advancements for these modern aircraft configurations enabling accurate mathematical model development for flight dynamics simulations based on wind-tunnel and flight-test data. The first part of the dissertation focuses on advances in flight-test system identification methods using small, fixed-wing, remotely-piloted, electric, propeller-driven aircraft. A generalized approach for flight dynamics model development for small fixed-wing aircraft from flight data is described and is followed by presentation of novel flight-test system identification applications, including: aero-propulsive model development for propeller aircraft and nonlinear dynamic model identification without mass properties. The second part of the dissertation builds on established fixed-wing and rotary-wing aircraft system identification methods to develop modeling strategies for transitioning, distributed propulsion, eVTOL aircraft. Novel wind-tunnel experiment designs and aero-propulsive modeling approaches are developed using a subscale, tandem tilt-wing, eVTOL aircraft, leveraging design of experiments and response surface methodology techniques. Additionally, a method applying orthogonal phase-optimized multisine input excitations to aircraft control effectors in wind-tunnel testing is developed to improve test efficiency and identified model utility. Finally, the culmination of this dissertation is synthesis of the techniques described throughout the document to form a flight-test system identification approach for eVTOL aircraft that is demonstrated using a high-fidelity flight dynamics simulation. The research findings highlighted throughout the dissertation constitute substantial progress in efficient empirical aircraft modeling strategies that are applicable to many current and future aeronautical vehicles enabling accurate flight simulation development, which can subsequently be used to foster advancement in many other pertinent technology areas. / Doctor of Philosophy / Small, electric-powered airplanes flown without an onboard pilot, as well as novel electric aircraft configurations with many propellers that operate at a wide range of speeds, referred to as electric vertical takeoff and landing (eVTOL) aircraft, have recently emerged as aeronautical vehicles able to perform new tasks for future airborne transportation methods. This dissertation presents several mathematical modeling research advancements for these modern aircraft that foster accurate description and prediction of their motion in flight. The mathematical models are developed from data collected in wind-tunnel tests that force air over a vehicle to simulate the aerodynamic forces in flight, as well as from data collected while flying the aircraft. The first part of the dissertation focuses on advances in mathematical modeling approaches using flight data collected from small traditional airplane configurations that are controlled by a pilot operating the vehicle from the ground. A generalized approach for mathematical model development for small airplanes from flight data is described and is followed by presentation of novel modeling applications, including: characterization of the coupled airframe and propulsion aerodynamics and model development when vehicle mass properties are not known. The second part of the dissertation builds on established airplane, helicopter, and multirotor mathematical modeling methods to develop strategies for characterization of the flight motion of eVTOL aircraft. Innovative data collection and modeling approaches using wind-tunnel testing are developed and applied to a subscale eVTOL aircraft with two tilting wings. Statistically rigorous experimentation strategies are employed to allow the effects of many individual controls and their interactions to be simultaneously distinguished while also allowing expeditious test execution and enhancement of the mathematical model prediction capability. Finally, techniques highlighted throughout the dissertation are combined to form a mathematical modeling approach for eVTOL aircraft using flight data, which is demonstrated using a realistic flight simulation. The research findings described throughout the dissertation constitute substantial progress in efficient aircraft modeling strategies that are applicable to many current and future vehicles enabling accurate flight simulator development, which can subsequently be used for many research applications.

No description available.

The ion acceleration process in Bipolar High Power Impulse Magnetron Sputteringis investigated for use in a novel space propulsion system - the BP-HiPIMS thruster.The interest for BP-HiPIMS has recently been growing within the area of thin filmdeposition due to the theorised acceleration of target ions caused by the reversedpulse following the regular HiPIMS pulse. This same acceleration could be usedto produce thrust in a space propulsion system, where the lack of physical gridsand temporal separation of ionisation and acceleration are attractive benefits of thesuggested system. In this paper the physical processes and parameters of importanceare experimentally investigated to gain understanding of the ion acceleration processwith the goal of verifying the theory of BP-HiPIMS thusters.Through plasma potential measurements a beneficial potential structure between themagnetic trap and bulk of the plasma which could potentially accelerate ions is foundat certain discharge conditions and some acceleration of ions is confirmed in massspectrometer measurements. The results are promising for a thruster application butfurther research is needed to evaluate the viability of the proposed system. / Jonaccelerationsprocessen i Bipolar High Power Impulse Magnetron Sputteringundersöks för användning i ett nytt framdrivningssystem för rymdfarkoster: BPHiPIMSthrusters. Intresset för BP-HiPIMS har ökat den senaste tiden inomtunnfilmsfysiken på grund av accelerationen av “target” joner som tros accelererasav den bipolära pulsen som följer den vanliga HiPIMS pulsen. Denna accelerationskulle också kunna användas för att skapa en framdrivande kraft som kan användassom motor på rymdfarkoster, där saknaden av accelererande galler och separationav jonisering och acceleration i tiden är attraktiva fördelar av det föreslagnasystemet. I denna rapport undersöks den fysikaliska processen och viktiga parametrarexperimentellt för att få en förståelse för jonaccelerationsprocessen med målet attverifiera teorin bakom “BP-HiPIMS thrusters”.Genom plasmapotentialmätningar kan en gynnsam potentialstruktur, mellan denmagnetiska fällan nära magnetronen och volymenutanför, som potentiellt kan accelerera joner uppmätas under vissa förhållanden, däracceleration av joner bekräftas av masspektrometri. Resultaten är lovande för ettelektriskt rymdframdrivningssystem, men ytterligare forskning krävs för att evaluerakonkurrenskraften av det föreslagna systemet.

A volume-averaged hollow cathode plasma model is presented that serves as a preliminary design tool for orificed hollow cathodes. The plasma discharge volume is subdivided into two computational domains with separate sub-models that are used to determine the emitter and orifice region plasma parameters. The plasma model is coupled with a lumped node thermal model that uses power inputs from the plasma model to estimate the temperature distribution of the hollow cathode. The model has been implemented for conventional cylindrical emitter geometries and for novel disc-shaped emitters. A lanthanum hexaboride (LaB6) hollow cathode has been used to validate the cylindrical model results and shows good agreement with well-known trends of hollow cathodes and published model data, while a calcium aluminate electride (C12A7:e-) hollow cathode developed at Technische Universität Dresden (TUD) served as the basis for the disc configuration. The model results of the disc configuration are presented and discussed to identify trends and optimization potential for hollow cathodes using C12A7:e- emitters. The model results in combination with thermal measurements of the TUD hollow cathode indicate a work function of C12A7:e- in a hollow cathode plasma below 2 eV.

L’effet Biefeld-Brown, du nom de ses découvreurs dans les années 1920, désigne la force électrohydrodynamique (EHD) s’appliquant sur deux électrodes sous haute tension dans l’air. Si l’origine de cette force a pu faire l’objet de certaines spéculations, il est aujourd'hui admis qu’elle repose sur l’accélération par un fort champ électrique d’un volume d’air partiellement ionisé. Cet effet aussi appelé vent ionique intéresse diverses applications : contrôle actif d’écoulement, augmentation du transfert de chaleur par convection forcée, séchage de denrées alimentaires ou encore la propulsion. Cette thèse, présente une étude expérimentale, théorique et numérique du vent ionique dans une configuration modèle à deux électrodes parallèles. Le faible rendement du vent ionique l’a écarté des applications à la propulsion mais des expériences récentes menées en 2013 montrent qu’il permet d’atteindre un rapport poussée/puissance étonnement élevé. Nous montrons dans une première partie, à partir de mesures et de considérations aérodynamique générales que la poussée générée pourrait suffire à contrebalancer la force de traînée pour certains aéronefs ultra-légers. Ces mesures ont permis de quantifier la force EHD et sa dépendance avec la géométrie des électrodes. En outre, la meilleure configuration à deux collecteurs peut produire une poussée presque deux fois plus importante qu’une configuration avec un seul collecteur, à tension fixée. Ces premiers résultats ont été affinés dans un second temps par les mesures PIV qui ont permis la reconstruction de l’écoulement et du champ de force entre les électrodes. Les vitesses mesurées dépassent rarement 3 m/s, et la force volumique est de l’ordre de 10 N/m 3. L’origine physique de la configuration optimale à deux collecteurs a été éclaircie par la mise en évidence des structures de sillages et de leurs effets instationnaires. Par ailleurs, une analyse théorique générale de la force propulsive nous a permis de confirmer sa dépendance explicite avec le rapport courant sur mobilité ionique. Le courant étant directement lié à la physique de la décharge couronne, la seconde partie de la thèse s’est concentrée sur son analyse théorique et numérique. Une analyse asymptotique a ainsi permis de trouver une expression analytique du champ électrique critique et de la caractéristique courant-tension permettant de connaître l’influence de la densité du gaz et de sa composition sur le courant produit dans des électrodes concentriques. Cette approche asymptotique a été associée à une formulation de décomposition de domaine dans le cadre d’une discrétisation par éléments finis pour analyser des configurations plus générales. Une résolution itérative du système d’équations stationnaires non-linéaire couplées par méthode de Newton est proposée, testée et validée. Cette méthode peut être étendue à des géométries plus complexes, permettant ainsi d’obtenir une condition d’injection des charges prenant en compte la physique complexe de la décharge. / The Biefeld-Brown effect, named after its discoverers in 1920s, stands for the electrohydrodynamic (EHD) force applied on two high voltage electrodes in air. The origin of this force has been subject to controverse, but it is establised that it relies on the acceleration of ionized air by a strong electric field. Numerous applications are associated with ionic wind : active flow control, heat transfer enhancement, food drying or even propulsion. At the first glance, the low efficiency is unattractive for propulsion. However recent experiments highlighted a surprisingly high thrust/power ratio. This PhD research aimed to better understand the phenomena, through experiments and theoretical or numerical analysis. First, an experimental study was carried out to quantify the EHD force and its variations with the geometry of the electrodes. For instance, the best position of two collecting electrodes could produce nearly twice more thrust than the one collector configuration, for a given applied voltage. Considering the mass and the aerodynamic of some already existing very light aircrafts, it is shown that the produced thrust could at most balance the aerodynamic drag. This first results were enhanced by PIV measurements, which gave deeper insight into the flow and the force field between the electrodes. The air speed recorded was at most around 3 m/s, while the volumetric force of the order of 10 N/m3. The physical explaination of the optimal two collectors configuration relied partially on the wake flow structures and their unsteady effects. Then, a theoretical analysis of the propulsive force confirmed its explicit dependence on the current to mobility ratio. The discharge current being determined by the corona discharge physics, the second part of this work focuses on its theoretical and numerical analysis. An asymptotic approach of the corona discharge for concentric cylindrical electrodes led to an explicit expression of both the onset surface electric field and the current-voltage law as functions of the gas density, the effective ionization coefficient and the electrodes size. This asymptotic approach was reformulated in the frame of a domain decomposition method, implemented numerically with a finite elements discretization, in order to generalize the asymptotic approach. The iterative algorythm for the steady non-linear coupled system of equations is based on Newton method. This method provides a physically relevant boundary condition for the charge injection and can be applied to more complex geometries.

Considerable resources worldwide are invested in the research and development of future transportation technology. The foreseen direction and therefore research of future personalised transportation is focused on Battery Electric Vehicles (BEV) or hybrid combinations that use hydrogen fuel cells. These new transport energy systems are consider most to replace the current vehicles powered by the internal combustion engine (ICE). The research work presented in this thesis mainly focuses on the development of a software control system for future BEV prototype vehicles - a generic intelligent control system (GICS). The system design adopts a modular design concept and intelligent control. The whole system consists of four modules being communication, power supply, motor driver and transmission module. Each module uses a microcontroller as the brain and builds an embedded control system within the module. The control and communication between the modules is based on a group of specific parameters and the status of a state machine. In order to effectively implement intelligent control and simplify the system structure and programming, a generic intelligent fuzzy logic model that can be configured to a specific application with a near real-time buffered communication methodology is developed. The tests made on the fuzzy control model and the near real-time buffered communication gave a very positive outcome. The implementation of the fuzzy control and the communication methodology in each of the modules results in a communication between the modules with a steady speed, better reliability and system stability. These modules link together through the communication channels and form a multi-agent collaborative system (MACS). As the controllers are designed based on the parametric concept, the system is able to be implemented to future new modules and therefore allow prototype vehicle control systems to be developed more efficiently. The MACS is based on the core components of the control system - fuzzy logic controller (FLC), Serial Communication and Analogue input control software modules. Further work is carried out as an attempt to integrate the control software with a hardware design for a generic electric propulsion drive (GEPD). This thesis therefore outlines the design and considerations in software and hardware integration in addition to the GICS. The output from this thesis being the construction of soft programming modules for embedded microcontroller based control system has been accepted and presented at two international conferences; one in Wellington, New Zealand[1] the second in Acireale, Italy[2].

Considerable resources worldwide are invested in the research and development of future transportation technology. The foreseen direction and therefore research of future personalised transportation is focused on Battery Electric Vehicles (BEV) or hybrid combinations that use hydrogen fuel cells. These new transport energy systems are consider most to replace the current vehicles powered by the internal combustion engine (ICE). The research work presented in this thesis mainly focuses on the development of a software control system for future BEV prototype vehicles - a generic intelligent control system (GICS). The system design adopts a modular design concept and intelligent control. The whole system consists of four modules being communication, power supply, motor driver and transmission module. Each module uses a microcontroller as the brain and builds an embedded control system within the module. The control and communication between the modules is based on a group of specific parameters and the status of a state machine. In order to effectively implement intelligent control and simplify the system structure and programming, a generic intelligent fuzzy logic model that can be configured to a specific application with a near real-time buffered communication methodology is developed. The tests made on the fuzzy control model and the near real-time buffered communication gave a very positive outcome. The implementation of the fuzzy control and the communication methodology in each of the modules results in a communication between the modules with a steady speed, better reliability and system stability. These modules link together through the communication channels and form a multi-agent collaborative system (MACS). As the controllers are designed based on the parametric concept, the system is able to be implemented to future new modules and therefore allow prototype vehicle control systems to be developed more efficiently. The MACS is based on the core components of the control system - fuzzy logic controller (FLC), Serial Communication and Analogue input control software modules. Further work is carried out as an attempt to integrate the control software with a hardware design for a generic electric propulsion drive (GEPD). This thesis therefore outlines the design and considerations in software and hardware integration in addition to the GICS. The output from this thesis being the construction of soft programming modules for embedded microcontroller based control system has been accepted and presented at two international conferences; one in Wellington, New Zealand[1] the second in Acireale, Italy[2].

Considerable resources worldwide are invested in the research and development of future transportation technology. The foreseen direction and therefore research of future personalised transportation is focused on Battery Electric Vehicles (BEV) or hybrid combinations that use hydrogen fuel cells. These new transport energy systems are consider most to replace the current vehicles powered by the internal combustion engine (ICE). The research work presented in this thesis mainly focuses on the development of a software control system for future BEV prototype vehicles - a generic intelligent control system (GICS). The system design adopts a modular design concept and intelligent control. The whole system consists of four modules being communication, power supply, motor driver and transmission module. Each module uses a microcontroller as the brain and builds an embedded control system within the module. The control and communication between the modules is based on a group of specific parameters and the status of a state machine. In order to effectively implement intelligent control and simplify the system structure and programming, a generic intelligent fuzzy logic model that can be configured to a specific application with a near real-time buffered communication methodology is developed. The tests made on the fuzzy control model and the near real-time buffered communication gave a very positive outcome. The implementation of the fuzzy control and the communication methodology in each of the modules results in a communication between the modules with a steady speed, better reliability and system stability. These modules link together through the communication channels and form a multi-agent collaborative system (MACS). As the controllers are designed based on the parametric concept, the system is able to be implemented to future new modules and therefore allow prototype vehicle control systems to be developed more efficiently. The MACS is based on the core components of the control system - fuzzy logic controller (FLC), Serial Communication and Analogue input control software modules. Further work is carried out as an attempt to integrate the control software with a hardware design for a generic electric propulsion drive (GEPD). This thesis therefore outlines the design and considerations in software and hardware integration in addition to the GICS. The output from this thesis being the construction of soft programming modules for embedded microcontroller based control system has been accepted and presented at two international conferences; one in Wellington, New Zealand[1] the second in Acireale, Italy[2].