The study of the motion of manoeuvring aircraft has traditionally considered the aircraft to be rigid. This simplifying assumption has been shown to give quite accurate results for the flight dynamics of many aircraft types. As modern transport aircraft have developed however, there has been a marked increase in the size and weight of these aircraft. This trend is likely to continue with the development of future blended-wing-body and supersonic transport aircraft. This increase in size and weight has brought about a unique set of aeroelastic and handling quality issues. The aerodynamic forces and moments acting on an aeroplane have traditionally been represented using the aerodynamic derivative approach. It has been shown that this quasisteady aerodynamic model inadequately predicts the aircraft’s stability characteristics, and that the inclusion of unsteady aerodynamics “greatly improves the fidelity” of aircraft models. This thesis thus presents a novel numerical simulation of an aeroelastic aeroplane for real-time analysis. The model is built around the standard six degree-of-freedom equations of motion for a rigid aeroplane using the mean-axes system, and includes unsteady aerodynamics and structural dynamics. This is suitable for pilot-in-the-loop simulation, handling qualities and flight loads analysis, and control law development. The dynamics of the structure are modelled as a set of normal modes, and the equations of motion are realised in state-space form. The unsteady aerodynamic forces acting on the aeroplane are described by an indicial state-space model, including unsteady tailplane downwash and compressibility effects. An implementation of the model is presented in the MATLAB/ Simulink environment. The interaction between the flight control system, the aeroelastic system and the rigidbody motion of the aeroplane can result in degraded handling qualities, excessive actuator control, and fatigue problems. The introduction of load alleviation systems for the management of loads due to manoeuvres and gusts is also likely to result in the handling qualities of the aeroplane being degraded. This thesis presents a number of studies into the impact of structural dynamics, unsteady aerodynamics, and load alleviation on the handling qualities of a flexible civil transport aeroplane. The handling qualities of the aeroplane are assessed against a number of different handling qualities criteria and flying specifications, including the Neal-Smith, Bandwidth, and CAP criterion. It is shown that aeroelastic effects alter the longitudinal and lateral-directional characteristics of the aeroplane, resulting in degraded handling qualities. Manoeuvre and gust load alleviation are similarly found to degrade handling qualities, while active mode control is shown to offer the possibility of improved handling qualities.

A dynamic flight model of a jet trainer aircraft is developed in MATLAB-SIMULINK. Using a six degree of freedom mathematical model, non-linear simulation is used to observe the longitudinal and lateral-directional motions of the aircraft following a pilot input. The mathematical model is in state-space form and uses aircraft stability and control derivatives calculated from the aircraft geometric and aerodynamic characteristics. The simulation takes the changes in speed and altitude into consideration due to pilot input and demonstrates the non-linearity of the aircraft motion. The results from the simulation are compared with the results from flight characteristics manual of the actual aircraft to validate the mathematical model used. The simulation is carried out for a number of airspeed and altitude combinations to examine the effect of changing speed and altitude on the aircraft dynamic response.

<div>In order to answer the most pressing scientific questions about the two Martian moons, Phobos and Deimos, new remote sensing observations are required. The best way to obtain global high resolution observations of Phobos and Deimos is through dedicated missions to each body that utilize close-proximity orbits, however much of the orbital tradespace is too unstable to realistically or safely operate a mission.</div><div><br></div><div>This thesis explores the dynamics and stability characteristics of trajectories near Deimos. The family of distant retrograde orbits that are inclined out of the Deimos equatorial plane, known as quasi-satellite orbits, are explored extensively. To inform future mission design and CONOPS, the sensitivities and stability of distant retrograde and quasi-satellite orbits are examined in the vicinity of Deimos, and strategies for transferring between DROs are demonstrated. Finally, a method for designing quasi-satellite science orbits is demonstrated for a set of notional instruments and science requirements for a Deimos remote sensing mission.<br></div>

<div>Studying the motion of cells and investigating their migration patterns in inertial microchannels have been of great interest among researchers because of their numerous biological applications such as sorting, separating, and filtering them. A great drawback in conventional microfluidics is the inability to focus extremely small biological particles and pathogens in the order of sub-micron and nanometers due to the requirement of designing an impractically elongated microchannel, which could be in the order of a few meters in extreme cases. This restriction is because of the inverse correlation between the cube of the particle size and the theoretically required channel length. Exploiting an oscillatory flow is one solution to this issue where the total distance that the particle needs to travel to focus is virtually extended beyond the physical length of the device. Due to the present symmetry in such flow, the directions of the lift forces acting on the particle remain the same, making the particle focusing feasible. </div><div><br></div><div>Here, we present results of simulation of such oscillatory flows of a single capsule in a rectangular microchannel containing a Newtonian fluid. A 3D front-tracking method has been implemented to numerically study the dynamics of the capsule in the channel of interest. Several cases have been simulated to quantify the influence of the parameters involved in this problem such as the channel flow rate, capsule deformability, frequency of oscillation, and the type of applied mechanism for inducing flow oscillations. In all cases, the capsule blockage ratio and the initial location are the same, and it is tracked until it reaches its equilibrium position. The capability to focus the capsule in a short microchannel with oscillatory flow has been observed for capsule deformabilities and mechanisms to induce the oscillations used in our study. Nevertheless, there is a limit to the channel flow rate beyond which, there is no single focal point for the capsule. Another advantage of having an oscillatory microchannel flow is the ability to control the capsule focal point by changing the oscillation frequency according to the cases presented in the current study. The capsule focusing point also depends on its deformability, flow rate, and the form of the imposed periodic pressure gradient; more deformable capsules with lower maximum velocity focus closer to the channel center. Also, the difference between the capsule equilibrium point in steady and oscillatory flows is affected by the capsule stiffness and the device flow rate. Furthermore, increasing the oscillation frequency, capsule rigidity, and system flow rate shorten the essential device length. </div><div><br></div><div>Although the oscillation frequency can provide us with new particle equilibrium positions, especially ones between the channel center and wall that can be very beneficial for separation purposes, it has the shortcoming of having a zero net throughput. To address this restriction, a steady component has been added to the formerly defined oscillatory flow to make it pulsating. Furthermore, this type of flow adds more new equilibrium points because it behaves similarly to a pure oscillatory flow with an equivalent frequency in that regard. They also enable the presence of droplets at high Ca or Re that could break up in the steady or a very low-frequency regime. Therefore, we perform new numerical simulations of a deformable droplet suspended in steady, oscillatory, and pulsating microchannel flows. We have observed fluctuations in the trajectory of the drop and have shown that the amplitude of these oscillations, the average of the oscillatory deformation, and the average migration velocity decrease by increasing the frequency. The dependence of the drop focal point on the shape of the velocity profile has been investigated as well. It has been explored that this equilibrium position moves towards the wall in a plug-like profile, which is the case at very high frequencies. Moreover, due to the expensive cost of these simulations, a recursive version of the Multi Fidelity Gaussian processes (MFGP) has been used to replace the numerous high-fidelity (or fine-grid) simulations that cannot be afforded numerically. The MFGP algorithm is used to predict the equilibrium distance of the drop from the channel center for a wide range of the input parameters, namely Ca and frequency, at a constant Re. It performs exceptionally well by having an average R^2 score of 0.986 on 500 random test sets.</div><div><br></div><div>The presence of lift forces is the main factor that defines the dynamics of the drop in the microchannel. The last part of this work will be dedicated to extracting the active lift force profiles and identify their relationships with the parameters involved to shed light on the underlying physics. This will be based on a novel methodology that solely depends on the drop trajectory. Assuming a constant Re, we then compare steady lift forces at different Ca numbers and oscillatory ones at the same constant Ca. We will then define analytical equations for the obtained lift profiles using non-linear regression and predict their key coefficients over a continuous range of inputs using MFGP.</div>

The Generic Planning Tool (GPT) is a new software package being developed by the Flight Dynamics team at DLR. In an era where laser communications are becoming more and more relevant to data transmission for space missions, the GPT’s purpose is to compute highly accurate visibility windows and provide a wide variety of support information for both satellite-to-ground and inter-satellite links. What sets the GPT apart from previous products, is its shift from mission-specific to multi-mission and being able to accept various orbit and attitude data formats, thus enabling the support of multiple missions from DLR and external clients with flight dynamics information for mission planning applications. Its two main components are the core libraries written in Fortran, which serve as the powerhouse for the orbital mechanic’s computations, and the microservice architecture, enabled by JSON input/output files and Python scripts, which implement an automatic request-response service accessible over the network. This thesis will present why, how, and which GPT software functionalities were developed and tested during the internship at the German Space Operation Center. / Det generiska planeringsverktyget, Generic planning tool (GPT), är ett nytt mjukvarupaket som utvecklas av den flygdynamiska avdelningen på DLR. I en tid när kommunikation med hjälp av laser blir alltmer relevant vid dataöverföringar för rymduppdrag, är syftet med GPT att beräkna mycket exakta öppningar för dataöverföringar, men också att bidra med en mängd olika sorters användbar information för både ”satellit-till-mark”- och ”satellit-tillsatellit”-länkar. Det som skiljer verktyget från tidigare produkter är dess omvandling från att vara uppdragsspecifik till att kunna hantera multipla uppdrag. I och med GPT:s förmåga att acceptera olika dataformat gällande omloppsbana och orientering, öppnar det upp för att kunna stödja multipla uppdrag från DLR och externa klienter med flygdynamisk information, för applikationer inom uppdragsplanering. GPT:s två huvudsakliga delar är, de centrala biblioteken skrivna i Fortran vilka verkar som ett kraftverk för de orbital-mekaniska beräkningarna, och mikroservice-arkitekturen skapad från JSON input/output-filer och Pythonskript, vilket implementerar en automatisk begär- och svarstjänst tillgänglig via nätverket. Detta examensarbete kommer presentera varför, hur och vilka av GPT:s mjukvarufunktioner som utvecklades och testades under praktikplatsen på German Space Operations Center (GSOC).

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.

<p> The abort mission refers to the mission where the landing vehicle needs to terminate the landing mission when an anomaly happens and be safely guided to the desired orbit. Missions involving crew on board demands for a robust and efficient abort strategy. This thesis focuses on solving the time-optimal abort guidance (TOAG) problem in real-time via the feature-based learning method. First, according to the optimal control theory, the features are identified to represent the optimal solutions of TOAG using a few parameters. After that, a sufficiently large dataset of time-optimal abort trajectories is generated offline by solving the TOAG problems with different initial conditions. Then the features are extracted for all generated cases. To find the implicit relationships between the initial conditions and identified features, neural networks are constructed to map the relationships based on the generated dataset. A successfully trained neural network can generate solution in real time for a reasonable initial condition. Finally, experimental flight tests are conducted to demonstrate the onboard computation capability and effectiveness of the proposed method. </p>

Aircraft system identification has been widely used to this day in applications like control law design, building simulators or extending flight envelopes. It can also be utilized for determining flight-mechanical characteristics in the preliminary design phase of a flight vehicle. In this thesis, three common time-domain methods were implemented in MATLAB for determining the aerodynamic derivatives of a subscale aircraft. For parameter estimation, the equation-error method is quick, robust and can provide good parameter estimates on its own. The output-error method is computationally intensive but keeps account of the aircraft's evolution in time, being more suitable for fine-tuning predictive models. A new model structure is identified using multivariate orthogonal functions with a predicted squared error stopping criteria. This method is based on linear regression (equation-error). The code written is flexible and can also be used for other aircraft and with other aerodynamic models. Simulations are compared with experimental data from a previous flight test campaign for validation. In the future, this tool may help taking decisions in conceptual design after a prototype is tested.

Esta dissertação apresenta o desenvolvimento da teoria de dinâmica de voo e o conceito de controle a ser aplicado na modelagem e simulação de voo de um VANT com decolagem e pouso vertical proposto. Um conceito de aeronave de asa semi-tandem é projetado e os coeficientes aerodinâmicos, propriedades inerciais e parâmetros de controle são estimados, o que permitiu a implementação da teoria proposta. O modelo fez uso das equações de movimento multi-corpos onde a aeronave é dividida em partes de forma que a asa, o estabilizador horizontal e os rotores sejam entidades independentes. Além disso, o sucesso da fase de transição de voo pairado para cruzeiro e de cruzeiro para voo pairado pode ser verificado se houver a possibilidade da aeronave trimar ao longo do regime de velocidades de voo, em outras palavras, se houver uma combinação de estados de movimento que mantenha a aeronave estável do voo pairado para a condição de cruzeiro. Assim, as curvas de trimagem que expressam os estados são calculadas usando a minimização de uma função de custo envolvendo a soma dos quadrados de alguns dos estados de movimento, definidos pelas equações de movimento mencionadas anteriormente. Tal minimização é realizada usando o algoritmo Simplex Sequencial. Além disso, é apresentada uma estratégia de controle que estabiliza a aeronave durante a transição de voo pairado para configuração de cruzeiro, que é testada em simulação computacional de um voo longitudinal acelerado e desacelerado, ou seja, de voo pairado para cruzeiro e de cruzeiro para voo pairado. Finalmente, um protótipo da aeronave estudada é apresentado. / This thesis presents the development of the flight dynamics theory and control concept to be applied in the modeling and flight simulation of a proposed VTOL UAV. A semi-tandem wing aircraft concept is designed and the aerodynamic coefficients, inertial properties and controls parameters are estimated, which allowed the implementation of the proposed theory. The model made use of the multi-body equations of motion where the aircraft is divided in parts so that the wing, horizontal stabilizer and rotors are independent entities. Additionally, the success of the transition phase from hovering to cruise and from cruise to hovering can be verified if there is the possibility of the aircraft to trim along the flight speed regime, in other words, if there is a combination of states of motion that keep the aircraft stable from hover to cruise condition. So, the trim curves expressing the states are computed using the minimization of a cost function involving the sum of the squares of some of the states of motion, defined through the equations of motion previously mentioned. Such minimization is performed using the Sequential Simplex algorithm. Moreover, a control strategy that stabilizes the aircraft while it transitions from hovering to cruise configuration is presented, which is tested in computer simulation of an accelerated and decelerated longitudinal flight, that is, from hovering to cruise condition, and from cruise to hovering condition. Finally, a prototype of the aircraft studied is presented.

Le siècle dernier a été le siècle de la révolution technologique. Les combustibles fossiles ont alimenté cette révolution technologique. Les défis auxquels notre société est confrontée, que ce soit le changement climatique ou la situation énergétique mondiale ou l’épuisement des réserves de combustibles fossiles, sont les défis les plus graves auxquels sont confrontés toutes les générations. L'énergie renouvelable est considérée comme la clé des problèmes énergétiques de notre société. De nombreuses technologies innovantes se font concurrence pour alimenter la prochaine révolution énergétique. Sources d'énergies renouvelables telles que l'énergie solaire, l'énergie éolienne, la biomasse, l'hydroélectricité, l'énergie géothermique, etc. Presque tous sont saisonniers, et sont donc des sources d'énergie discontinues et non uniformes. Ils ont également une limitation en termes de choix des sites de production et, en général, nécessitent de grandes étendues de terre pour les plantes, ce qui conduit à une faible densité de puissance par unité de surface.Néanmoins, l'énergie éolienne et solaire a beaucoup attiré l'attention au cours des dernières décennies. Cependant, pour que le monde passe complètement des énergies fossiles et de l’énergie nucléaire à l’énergie éolienne et solaire, il est nécessaire de développer de nouveaux types de systèmes capables de générer de l’énergie à moindre coût avec moins de contraintes de sélection de sites.Dans la quête de la source d'énergie pérenne. Notre société se tourne vers la communauté scientifique pour des solutions innovantes. Cette thèse est une étape vers la recherche de solutions innovantes à nos problèmes énergétiques. Les systèmes d'énergie éolienne à haute altitude (HAWE) ou plus communément appelés systèmes éoliens aéroportés (AWES) sont considérés comme la réponse aux besoins énergétiques des générations futures. L'énergie éolienne aéroportée (AWE) est un concept innovant visant à utiliser l'énergie des courants de vent à haute altitude, car les courants de vent à haute altitude sont presque uniformes dans le monde entier et AWES peut pratiquement être installé partout dans le monde. De plus, les systèmes AWE proposés nécessitent moins de matériau de structure. Ils devraient donc être beaucoup moins chers que toute autre source d’énergie disponible. AWE est donc une perspective prometteuse dans cette quête pour trouver une solution à nos problèmes énergétiques.Dans ce travail, la faisabilité des systèmes d'énergie éolienne aéroportés basés sur Magnus est explorée. Le travail présente en détail un bref historique des systèmes d'énergie éolienne aéroportés et des concepts de base nécessaires pour développer une compréhension de la technologie AWE. Il examine en détail les systèmes aéroportés basés sur Magnus et donne une perspective historique sur les machines basées sur l’effet Magnus. Il présente en détail les propriétés aérodynamiques de l’effet Magnus et présente un modèle aérodynamique pour ces systèmes. Puisque la modélisation est un aspect important de toute technologie. Ce travail présente un modèle détaillé des systèmes AWE basés sur Magnus ainsi que les algorithmes de contrôle nécessaires au fonctionnement de tels systèmes. Les courbes de puissance sont des outils couramment utilisés pour analyser les systèmes d'énergie éolienne. Ce travail présente une approche pour la conception de courbes de puissance pour les systèmes AWE afin d'analyser les capacités de production d'énergie des systèmes d'énergie éolienne aéroportés. / Last century has been the century of the technology revolution. Fossil fuels have fueled this technology revolution. The challenges faced by our society be it the climate change or the world energy situation or the depletion of fossil fuel reserves are the most grievous challenges faced by any generation. Renewable energy is believed to be the key to energy problems of our society. There are many innovative technologies competing against each other to fuel the next energy revolution. Renewables sources of energies such as solar, wind, biomass, hydropower, geothermal etc. Though promising but due to the high economic cost and limited application they are yet to prove their mass scale applicability. Almost all of them are seasonal, hence, are discontinuous and non-uniform sources of energy. They also have a limitation in terms of choice of plant sites, and generally, require large tracts of land for plants which lead to low power density per unit area.Nonetheless, Wind and Solar energy have attracted a lot of attention in the last few decades. However, for the world to fully shift from fossil fuels and nuclear energy to Wind and Solar power, it is necessary to develop new kind of systems which can generate continuous power at a lower cost with fewer site selection constraints.In the quest to find the perennial clean source of energy. Our society is looking towards the scientific community for innovative solutions. This thesis is one such step towards finding innovative solutions to our energy problems. High altitude wind energy systems (HAWE) or more commonly known as Airborne wind energy systems (AWES) are believed to be the answer to the energy needs of the future generations. Airborne wind energy (AWE) is an innovative concept aiming at utilizing the energy of the high altitude wind currents, as high altitude wind currents are almost uniform across the globe, and AWES can be practically set-up anywhere around the world. Also, the proposed AWE systems require less structural material. Thus, they are expected to be much cheaper than any other available energy source. Therefore, AWE is a promising prospect in this quest to find a solution to our energy problems.In this work, the feasibility of Magnus-based airborne wind energy systems is explored. The work presents in detail a brief history of Airborne wind energy systems and the basic concepts needed to develop an understanding about the AWE technology. It discusses in detail Magnus-based airborne systems and gives a historical perspective on the Magnus-effect based machines. It discusses in detail the aerodynamical properties of the Magnus effect and presents an aerodynamic model for such systems. Since modeling is an important aspect of any technology. This work presents a detailed model of the Magnus-based AWE systems along with the control algorithms required for the operation of such systems. A common tool used to analyze wind-based energy systems is power curves. This work presents an approach to design power curves for AWE systems in order to analyze the power producing capabilities of Airborne wind energy systems.