The drone industry is growing and the need for increased autonomy will be required if large fleetof drones will be able to fly without a single pilot per drone. A useful part of automating the flighten-route can be achieved with the upcoming standard of Direct Remote Id (DRI), which signalspositional data for drones and can be used as the perceptive part in a collision avoidance systembetween drones with the advantage of limited weight penalties and minimal financial cost.Simulations were carried out to understand different kinds of evasive maneuvers and develop asimple yet effective algorithm for avoiding obstacles and continue towards the next waypoint ona mission. Positional data can be retrieved with an ESP-32 board from a flight computer withMavlink protocol, which can then be broadcasted and received to an ESP-32 board using DirectRemote Id. The distances between the nearest drones can be computed, along with the shortest al-lowable distance and closest positions of the drones, if they were to continue on a straight course. Ifthe closest passing distance turned out closer than a set safety distance, an evasive maneuver is cal-culated and executed, with preliminary work focusing on evasion maneuvers on an horizontal plane.Flight tests showed that an evasive position could be calculated, and the drone successfully di-verted to it, while continuing with the mission after the evasion was completed. These resultsshowed the potential of using Direct Remote Id as a simple close proximity detection for use withcollision avoidance / Drönarindustrin växer allt snabbare och det kommer att krävas en större grad av autonomitet för att kunna få drönare att flyga av sig själva utan att ha en pilot per drönare. En användbar del av att kunna autonomisera flygrutten vid flykt kan vara den nya standarden Direct Remote Id (DRI), som sänder ut positionsdata för den individuella drönaren och kan användas för att kunna upptäcka och bli upptäckt av andra drönare med minimal vikt- och priskostnad.Simuleringar gjordes för att undersöka samt förstå olika typer av undanmanövrar och för att utveckla en simpel och effektiv algoritm för att kunna undvika objekt och fortsätta med en planerad rutt. Positionsdata kan skickas till ett ESP-32 kretskort fån en flygdator med hjälp av Mavlink protokoll, denna data kan sedan sändas och bli mottaget av ett annat ESP-32 kretskort med Direct Remote Id standarden. Avståndet till den närmsta drönaren kan beräknas samt den minsta passagedistansen mellan drönarna om de skulle fortsätta i rak riktning. Om den minsta passagedistansen mellan drönarna är mindre än ett satt säkerhetsavstånd, beräknas en undanmanöver samt utförs. Flygtester visade att en undanmanöver kunde beräknas samt att drönaren omdirigerades till sidan om objektet och därefter fortsatte på sin planerade flygrutt. Dessa resultat visade potentialen i att använda Direct Remote Id som ett enkelt sätt att upptäcka andra drönare för att användas i ett kollisionsundvikande system.

The prediction of contrails have been studied since the 1930s primarily for militaryapplications. In present times, contrail avoidance strategies are gaining popularity insustainable aviation. In this project, the theory behind their formation, persistenceand the mitigation strategies are explored, studied and implemented.Several methods are evaluated in order to predict the critical temperature. Aircraftparameters are included in the prediction of contrails and implemented. This dynamicprogramming is contrasted against real case operational flight plans.The first implementation considers an operational flight plan for which contrails are pre-dicted along the trajectory. The second involves the prediction of contrails at the end ofthe vertical trajectory optimisation. The optimisation for contrail persistence avoidanceis also accomplished. Results show that contrail persistence can be avoided. / Förutsägelsen av kondensspår har studerats sedan 1930-talet, främst för militära tillämp-ningar. I nutid, strategier för undvikande av långvariga kondensspår ökar i popularitetinom hållbar flygning. I det här examensarbetet, utforskas och studeras teorin bakombildning, uthållighet och begränsningsstrategier för kondensspår för att sedan imple-menteras.Flera metoder evalueras för att förutsäga den kritiska temperaturen. Flygplansparame-trar är inkluderade och implementerade i förutsägelsen av kondesspår. Den dynamiskaprogrammeringen jämförs mot verkliga operativa färdplaner.Den första implementeringen avser en operativ färdplan för vilken kondensspår förut-spås längs banan. Den andra implementeringen involverar förutsägelse av kondensspåri slutet av den vertikala banoptimeringen. Optimeringen med avseende på långvarigakondensspår genomförs också. Resultaten visar att långvariga kondensspår kan und-vikas.

Over the past decade, there has been a considerable increase in space exploration efforts, driving the need for new methods to examine planets and other celestial bodies. The current trend involves designing spacecraft capable of surveying surfaces from elevated positions, with drones proving to be more suited for the task. . The focus of space missions has primarily been on exploring Mars, as evidenced by the pioneering flight of the Ingenuity helicopter in 2021. The Martian environment poses significant aerodynamic challenges due to its thin atmosphere and low pressure, complicating drone flight. The generation of lift is problematic owing to the scant atmosphere and the restricted dimensions required for space missions, resulting in low-chord Reynolds number flows. Despite the reduction in skin friction drag due to lower viscosity, the decrease in airfoil efficiency is significantly compromised, with only a partial counterbalance by the reduced gravitational pull. Two main challenges must be addressed: low chord-based Reynolds number flows and Martian dust. The former results in the formation of Laminar Separation Bubbles (LSB), severely impairing the aerodynamic efficiency of the airfoil. Concurrently, the accumulation of dust particles on the airfoil’s surface significantly affects its performance, altering its geometry and surface roughness. Thus, it is crucial to accurately determine the presence and location of both separation bubbles and particle deposition to predict performance degradation. \\This thesis presents a comprehensive survey on drones for planetary exploration and an analysis conducted on a cambered plate with 6$\%$ camber and 1$\%$ thickness, ideal for the types of flows considered. The studies are carried out for Reynolds number flows, namely 20,000 and 50,000, to observe the effects of rotor and airfoil dimensions. The computational study is performed using ANSYS Fluent, utilising a two-dimensional CFD model with a C-type mesh and the gamma-Re ($\gamma-Re_{\theta}$) transition model, which aids in capturing the behaviour of these flow regimes. Additionally, for the dust study, two phases are created: a primary phase, the atmosphere, and a secondary phase, the dust particles. The volume fraction of particles is assumed to be small enough to imply that the primary phase influences the secondary, but not vice versa (one-way coupling). To assess particle adhesion, a deposition model has been developed to check for the deposition of dust particles, working in conjunction with the Discrete Phase Modelling (DPM), which simulates the trajectory of particles within the control volume. The deposition model comprises a particle transport model, which accounts for the forces acting on the particles, and a particle-wall interaction model, which determines the particles' rebound or adhesion. The results are presented and discussed at the end of the thesis, along with a brief discussion of future studies focusing on alternative assumptions for dust modelling.

In this thesis, the design and particularities of a unique and revolution- ary scalable propulsion system are presented. A spacecraft mechanical design is included together with a mission definition, aiming to provide a context for a technology demonstration in space of an Hybrid Rocket Motor (HRM) as satellite thruster. Rocket motors have been around for many decades, with their use mainly focused on launch vehicles and large satellites, thus restricting the access to space to institutions with big budgets. To overcome this limitation, the application of a cost-effective type of rocket motor without a heritage of space utilization is explored. This is the implementation of an HRM as satellite thruster. In Chapter 2, the characteristics of this particular case of chemical rocket motor are presented in detail. The HRM applied for the present mission is a particular case of an in- house developed motor design method. As presented in Chapter 7, a scalable and versatile mechanical and propulsion design have been elab- orated following the maturation of a scalability software (Appendix A). The combination of these constitute a valuable tool allowing for a fast and accurate motor design for the desired scenario. Taking advantage of this straightforward tool, an attractive mission was defined to provide a meaningful context for the maiden use of an HRMin space. A micro satellite deep space mission, defined in Chapter 3, was chosen to validate the tool and prove Hybrid Rocket Motors (HRMs) capabilities, showing the benefits of its use over other propulsion systems already available, specifically in the small satellite family. The spacecraft design was tackled aiming to support the motor’s scalable concept while complying with the mission requirements and space standards. The out- come is an easily adaptable satellite design, justified in Chapter 8. The performed structural simulations are outlined in Appendix C to validate the developed design. Ultimately, this thesis work intends to provide the space community with a noteworthy product, opening the access to interplanetary missions provided the reduced mission costs of small satellites mounted with anHRM as propulsion system. Arising from the thesis content, research papers (Part v) have been published and presented in distinguished congresses, contributing to space development.

Satellite laser ranging provides an opportunity to track spacecraft trajectory fluctuationsas well as contributes to study of Earth’s tectonic motions and parameters ofMoon motions. Routine operations of laser ranging are carried out during night-timewhen noise probability is low. Classical approach for distance estimation includesdistance prediction thus reflected signal is expected to arrive during known time intervalcalled gate, however this is not possible when targeted object trajectory is notknown. In these cases gateless registration mode can be applied, but this mode greatlyreduces signal-to-noise ratio. In this thesis filter for noise event reduction during gatelessor full event registration was successfully developed. The filter is applied duringthe post-processing stage to improve signal-to-noise ratio of gathered data from laserranging. Not only the application of filter resulted in reduction of noise events, butalso it provides an insight whether there is an actual useful signal being emitted fromspacecraft. Investigation of event loss during full registration showed loss probabilityof 7.6% for calculated noise rate of 19 events per 0.01 millisecond. The developedfilter in combination with gateless registration mode opens the door for precipitationaltitude determination.

Modeling of complex mechanical systems faces challenges throughout the systems lifecycle. From keeping track of evolving system requirements during development to design configuration and version control for legacy models. Methodologies such as Model-Based System Engineering (MBSE) emphasize the utilization of information already embedded in models to aid in the propagation of information between disciplines and stakeholders. By automating the creation of digital artifacts and standardizing their formatting, robust connections between specialized engineering tools can be generated and full adoption of MBSE is possible. One such connection that must be established for MBSE adoption is between tools for geometrical design, such as CATIA V5, and tools for system simulation. The Functional Mock-up Interface (FMI) and System Structure and Parameterization (SSP) standards have been shown to provide a viable standardized format for coupling geometrical Computer Aided Design (CAD) models with system simulation models. However, the application of such standards coupled with geometrical design is still in its infancy and more research is needed to prove its usability and establish functional methodologies in an industry setting. The goal of the thesis was to further develop the application of the SSP standard on a geometrical CAD model of a Coolant Distribution System (CDS), and through automation estimate deterministic simulation parameters. The work was carried out at Saab Aeronautics in Linköping, Sweden. By utilizing the industry as laboratory method, the industry-grade geometrical CAD models were used to converge the research and the industry needs to make the resulting proposed methodology applicable in an industry setting. The work showed that with the help of automated frameworks, deterministic simulation data can be retrieved from new and legacy geometrical CAD models of CDS whilst complying with version control protocols. The implemented automation frameworks were able to estimate pressure loss coefficients for the different parts included in the CDS such as pipes, hoses, and couplings. Additionally, other needed simulation data such as lengths, insulation coverage, and inlet coordinates for the simulation components was also extracted from the geometrical model. By utilizing the presented method of isolated mapping, parts in the geometrical CAD model could be mapped to the correct simulation component whilst offering substantial flexibility and minimal editing of the models. Ultimately, the work showed that the tools needed for using automation for interoperability between geometrical design and system simulation does already exist. With automation frameworks and necessary knowledge integrated into the geometrical models, the field of geometrical design is shown to be ready for MBSE adoption.

Functioning satellite communication is a key part in everyday life and this thesis aims to contribute to the research area by exploring the characterisation of electrostatic discharges on antennas. Currently there is a gap in the research field when it comes to discharges on antennas and this thesis aims to try to fill that gap. Currently most research involves expensive electron beam and vacuum chamber testing. Simpler and more cost effective test methods are not as explored. This thesis explores current spacecraft charging and Electrostatic Discharge (ESD) standards, and how they can be used to analyze the charging and discharging characteristics of an antenna. The thesis involves how such a analysis is done and what limitations it may have. Two practical direct injection tests were also performed as to see how the antenna reacts to discharges of different energies and voltages. Finally a proposal of a test setup for an electron beam test was done. The main findings of the thesis is that there may be a risk of sustaining damage from the level of discharges measured despite the antenna fulfilling current standards and recommendations. Another take-away is that more research is required to establish if simpler analytic or practical tests are applicable for characterising discharges on the antenna.

I dagens samhälle är flygplan det snabbaste och ibland ett livsviktigt transportmedel. Med nutidens teknologi är det inte möjligt att tillverka ett passagerarflygplan som drivs av el då det skulle bli för tungt. Elen produceras av bränsleceller som drivs av vätgas. Detta projekt går ut på att ta fram en innovativ vingintegrerad kryotank för flytande väte som ska möjliggöra interkontinentala flygningar med hjälp av bränsleceller. Den teoretiska delen av projektet handlar om att dimensionera en cylindrisk tank med kupade gavlar mot förekommande laster. Det praktiska handlar om att lyckas svetsa ihop en vakuumtät spalt för ett termoskärl. Syftet med detta projekt är att identifiera ett möjligt tankmaterial som klarar av den låga temperaturen och alla krafter som den kan utsättas för. Kraven som sattes på tanken varatt den skulle klara accelerationer på 8,5 g och ett inre övertryck på 8 bar med trefaldig säkerhet mot plastisk deformation av materialet. Syftet med testtanken var att skapa vakuumtäta svetsfogar. Projektet utmynnade i ett val av aluminiumlegeringen 2091 som tankmaterial. Kravet påtrefaldig säkerhet mot plastisk deformation av tankmaterialet innebär att en minimitjocklek kan beräknas. En något högre tjocklek valdes och tankens geometri var således fastställd.Tanken hållfastighetsberäknades för förekommande laster och befanns uppfylldasamtliga uppställda krav. Efter att risken för buckling vid böjning utretts, kan godstjockleken slutligt fastställas. Av kostnadsskäl bör då i första hand en kommersiellt tillgänglig plåttjocklek väljas. Att utreda risken för buckling ligger utanför uppdragets ramar, men rekommenderas i fortsatta arbeten. / In today’s society airplanes is the fastest and sometimes vital means of transport. With modern technology it is not possible to manufacture a passenger aircraft which is powered by electricity as it would be too heavy. To eliminate carbon dioxide emissions from airplanes, the electricity can be produced by fuel cells powered by hydrogen gas. This project aims to develop an innovative winginregrated cryotank for liquid hydrogen that will enable intercontinental flights using fuels cells. The theoretical part of the project is about dimensioning a cylindrical tank with domed ends against occurring loads. The practical part was about succeeding in welding together a vacuum-tight gap for a thermos container. The purpose of this project was to identify a possible tank material that can withstand the low temperature and all the forces that can be subjected to it. The requirements placed on the tank were that it should withstand accelerations of 8,5 g and an internal excess pressure of 8 bar with triple safety against plastic deformation of the material. The purpose of the test tank was to create vacuum-tight weld joints. The project culminated in a choice of aluminum alloy 2091 as tank material. The requirement for threefold safety against plastic deformation of the tank material means that a minimum thickness can be calculated. A slightly higher thickness was chosen, and the geometry of the tank was thus determined. The tank’s strength was calculated for existing loads and found to meet all set requirements. After the risk of buckling during bending has been investigated, the material thickness can finally be determined. For economical reasons, a commercially available plate thickness should then be chosen in the first place. Investigating the risk of buckling is outside the scope of the assignment but is recommended in further work.

This master thesis addresses the development of an automatic numerical tool for thermal analysis, focusing on thermal systems comprising a printed circuit board assembly and cooling case structure. The project, conducted in collaboration with Unibap, aims to enhance the design process of space computer modules by automating middle steps between design software and thermal analysis results. The numerical tool employs the lumped parameter method, implemented in Python, as an alternative to traditional finite element analysis to efficiently generate thermal results. Informed decisions can be made using the tool regarding case-cooling and the selection of components requiring cooling, thus optimizing manufacturing costs and design complexity. The project results in the successful development of the automatic numerical tool. A unique method to derive values for thermal resistance within the case structure is also utilized. Though experimental test results for verification are pending, the functionality of the tool is presented along with results from a thermal analysis where it is used.

<p>The overall goal of the research presented in this thesis is to extend the physical understanding of the unsteady external aerodynamics associated with highly maneuverable delta-wing aircraft by using and developing novel, more efficient computational fluid dynamics (CFD) tools. More specific, the main purpose is to simulate and better understand the basic fluid phenomena, such as vortex breakdown, that limit the performance of delta-wing aircraft. The problem is approached by going from the most simple aircraft configuration - a pure delta wing - to more complex configurations. As the flow computations of delta wings at high angle of attack have a variety of unusual aspects that make accurate predictions challenging, best practices for the CFD codes used are developed and documented so as to raise their technology readiness level when applied to this class of flows.</p><p>Initially, emphasis is put on subsonic steady-state CFD simulations of stand-alone delta wings to keep the phenomenon of vortex breakdown as clean as possible. For half-span models it is established that the essential characteristics of vortex breakdown are captured by a structured CFD code. The influence of viscosity on vortex breakdown is studied and numerical results for the aerodynamic coefficients, the surface pressure distribution and breakdown locations are compared to experimental data where possible.</p><p>In a second step, structured grid generation issues, numerical aspects of the simulation of this nonlinear type of flow and the interaction of a forebody with a delta wing are explored.</p><p>Then, on an increasing level of complexity, time-accurate numerical studies are performed to resolve the unsteady flow field over half and full-span, stationary delta wings at high angle of attack. Both Euler and Detached Eddy Simulations (DES) are performed to predict the streamwise oscillations of the vortex breakdown location about some mean position, asymmetry in the breakdown location due to the interaction between the left and right vortices, as well as the rotation of the spiral structure downstream of breakdown in a time-accurate manner. The computed flow-field solutions are visualized and analyzed in a virtual-reality environment.</p><p>Ultimately, steady-state and time-dependent simulations of a full-scale fighter-type aircraft configuration in steady flight are performed using the advanced turbulence models and the detached-eddy simulation capability of an edge-based, unstructured flow solver. The computed results are compared to flight-test data.</p><p>The thesis also addresses algorithmic efficiency and presents a novel implicit-explicit algorithm, the Recursive Projection Method (RPM), for computations of both steady and unsteady flows. It is demonstrated that RPM can accelerate such computations by up to 2.5 times.</p>