<p>Current indirect optimal control problem (IOCP) solvers, like beluga or PINs, use symbolic math to derive the necessary conditions to solve the IOCP. This limits the capability of IOCP solvers by only admitting symbolically representable functions. The purpose of this thesis is to present a framework that extends those solvers to derive the necessary conditions of an IOCP with fully numeric methods. With fully numeric methods, additional types of functions, including conditional logic functions and look-up tables can now be easily used in the IOCP solver.</p> <p><br></p> <p>This aim was achieved by implementing algorithmic differentiation (AD) as a method to derive the IOCP necessary conditions into a new solver called Giuseppe. The Brachistochrone problem was derived analytically and compared Giuseppe to validate the automatic derivation of necessary conditions. Two additional problems are compared and extended using this new solver. The first problem, the maximum cross-range problem, demonstrates a trajectory can be optimized indirectly while utilizing a conditional density function that switches as a function of height according to the 1976 U.S. atmosphere model. The second problem, the minimum time to climb problem, demonstrates a trajectory can be optimized indirectly while utilizing 6 interpolated look up tables for lift, drag, thrust, and atmospheric conditions. The AD method yields the exact same precision as the symbolic methods, rather than introducing numeric error as finite difference derivatives would with the benefit of admitting conditional switching functions and look-up tables. </p>

<p dir="ltr">The electrification of pneumatic or hydraulic system on aircraft has been shown effective in reducing the fuel burn. Recently, electrifying propulsive loads has attracted a lot of atten- tion to further improve fuel economy. This work focuses on tools to facilitate more electric aircraft at conceptual design stage, particularly assuming a turbo-generator architecture. Specifically, we develop a simulation tool, mimicking SUAVE [1], which allows mission and fuel burn analysis. Major differences from SUAVE include more detailed models of compo- nents in the electric propulsive branch and degrees of freedom to adjust the velocity profile along the entire mission. Based on the simulator, this work further proposes to leverage a gradient-free optimization technique, which optimizes the optimal velocity profile along the entire mission to minimize fuel burn. Simulation results on two aircraft designs, a con- ventional Boeing 737-800 and NASA-STARC-ABL, verify the effectiveness of the proposed tools.</p>

Aircraft are not allowed to take off prior to cleaning of snow and ice deposits that form on their surfaces under winter conditions to refrain from compromising flight safety. Water based solutions containing mainly ethylene or propylene glycol, or both, are employed either to remove the snow/ice layers or to provide protection against deposition of these layers. The first group of solutions, i.e. de-icing fluids, are Newtonian and have generally low viscosity so that right after their application they fall off the aircraft surfaces, providing little or no further protection against precipitation. Therefore, various anti-icing solutions have then been developed to provide the prolonged protection due to their non-Newtonian and high viscosity characteristics. Although the appropriate ranges of viscosity and surface tension have been determined in a number of studies, actual compositions of these solutions are proprietary. The main objective of this study is to determine the basic interactions between the chemical species in de/anti-icing fluids and their effects on the physical properties of the solutions, especially viscosity, surface tension,freezing point and corrosive effect which enable the design of the de/anti icing fluid composition. A number of polymers and surfactants were dissolved in water-glycol solutions and used in different compositions to get the desired viscosity and surface properties. The dependence of viscosity on polymer concentration, pH of the solutions, glycol content, surfactant concentration, temperature and shear rate were investigated and reported in detail. Among various chemicals, slightly crosslinked and hydrophobically modified polyacrylic acid was utilized as a thickener, sodium oleate and tributyl amine were used as surface agents in the de/anti-icing solutions whose physical properties satisfied the desired requirements. In addition to the studies about de/anti icing solutions, synthesis of a new polymer namely poly (DADMAC-co-vinyl pyyrolidone) was made and its characterization and performance tests were performed. High swelling ratios (up to 360) were attained with 0.5 % crosslinker in 2-3 minutes. Moreover, swellings of the gels were demonstrated to be independent of pH. It was also thought that such a copolymer having anti-bacterial effect induced by DADMAC (Diallyldimethyl ammonium chloride) segments and biocompatability of NVP (N-vinyl pyyrolidone) component would be of interest in biorelated areas.

Navtech är en internationell leverantör av flygoperationella produkter. Det här examensarbetet utfördes på en av deras produktionsavdelning som kallas Aircraft Performance, i Stockholm. Arbetet består av framtagning av en manual till en mjukvaruprodukt. Produkten är ett program som beräknar och presenterar flygprestandainformation för start och landning. Programmet tillhandahålls med två användarmanualer, Userguide och Prepages. Dessa manualer beskriver hur programmet fungerar och hur det presenterade flygprestandainformation skall användas. Företaget har funnit ett behov av att förbättra innehållet av dessa två manualerna och vill ha hjälp med att skapa en ny, enhetlig och lättanvänd manual. För det har upptäckts att manualerna som tillhandahålls till kunderna inte alltid innehåller all grundläggande information om programmet och lett till att kunderna behöver kontakta Aircraft Performance kundsupport för hjälp och vägledning. Förutom att den nya manualen skulle vara enhetlig ville företaget att innehållet skulle vara generellt och fungera som en grundmall. Detta för att den sedan kunna anpassas efter varje nytt specifikt program. Den nya framtagna manualen har fått namnet Aircraft Performance Manual. För att informationen skall vara konsekvent i hela Aircraft Performance Manual för ett specifikt program har riktlinjer, kallad Developer guidelines, tagits fram under examensarbetet. De beskriver steg för steg vilken information som behöver anpassas för programmet. Denna rapport är en studie av programmets funktionaliteter och manualernas innebörd (Userguide och Prepages) samt Navtechs interna dokumenter som också är relaterad till programmet. Rapporten presenterar resultatet av det första upplägget av Aircraft Performance Manual, som är godkänd av Geneth Daley, Product Manager på Aircraft Performance avdelningen. I och med att Aircraft Performance Manual har blivit ett mycket stort dokument har vissa delar i denna lämnats med förslag till vidare utveckling och bearbetning. Detta är presenterad i slutet av rapporten. / Navtech is an international supplier of flight operational products. This thesis is performed in one of their production department called Aircraft Performance, in Stockholm. The work consists of development of a manual to a software product. The software calculates and presents aircraft performance information for takeoff and landing. The software is provided with two user manuals called Userguide and Prepages. These manuals supply information of how the software works and how to apply the flight performance information. The company has found needs of improving the contents in these manuals and needs help to develop a new and uniform manual that is easy-to-use. It has been discovered that the manuals which have been provided to customers does not always consist of all fundamental information about the software. The consequence of this has led customers to contact Aircraft Performance customer service for help and guidance. In addition to have a uniform manual, the company wants it to be generic and be used as a basic template. The reason is to be able to customize it for every new specific software. The newly developed manual is called Aircraft Performance Manual. To be able to maintain consistent information in the Aircraft Performance Manual for specific software a guideline, called Developer guidelines, has been created during the thesis work. It describes step by step which information needs to be customized for the software. This report consist study of the software functionality, the purpose of the manuals (Userguide and Prepages) and Navtechs internal documentations which also contains information related to the software. The report presents the first edition of the Aircraft Performance Manual, which is approved by Geneth Daley, the Product Manager of Aircraft Performance department. Because Aircraft Performance Manual has become a huge document, some parts have been left out with suggestions for further development och processing. They are presented in the end of this report.

abstract: The objective of this study is to understand how to integrate conical spike external compression inlets with high bypass turbofan engines for application on future supersonic airliners. Many performance problems arise when inlets are matched with engines as inlets come with a plethora of limitations and losses that greatly affect an engine’s ability to operate. These limitations and losses include drag due to inlet spillage, bleed ducts, and bypass doors, as well as the maximum and minimum values of mass flow ratio at each Mach number that define when an engine can no longer function. A collection of tools was developed that allow one to calculate the raw propulsion data of an engine, match the propulsion data with an inlet, calculate the aerodynamic data of an aircraft, and combine the propulsion and aerodynamic data to calculate the installed performance of the entire propulsion system. Several trade studies were performed that tested how changing specific design parameters of the engine affected propulsion performance. These engine trade studies proved that high bypass turbofan engines could be developed with external compression inlets and retain effective supersonic performance. Several engines of efficient fuel consumption and differing bypass ratios were developed through the engine trade studies and used with the aerodynamic data of the Concorde to test the aircraft performance of a supersonic airliner using these engines. It was found that none of the engines that were tested came close to matching the supersonic performance that the Concorde could achieve with its own turbojet engines. It is possible to speculate from the results several different reasons why these turbofan engines were unable to function effectively with the Concorde. These speculations show that more tests and trade studies need to be performed in order to determine if high bypass turbofan engines can be developed for effective usage with supersonic airliners in any possible way. / Dissertation/Thesis / Run file and text files from the propulsion simulations performed in NPSS. / Input and output file used in EDET to generate aerodynamic data of Concorde. / Five column propulsion data of tested engines after inlet matching. / Masters Thesis Aerospace Engineering 2018

Over the last few decades, many factors, including increased electrification, have led to a critical need for fast and efficient transient cooling. Thermal management systems (TMSs) are typically designed using steady-state assumptions and to accommodate the most extreme operating conditions that could be encountered, such as maximum expected heat loads. Unfortunately, by designing systems in this manner, closed-loop transient performance is neglected and often constrained. If not constrained, conventional design approaches result in oversized systems that are less efficient under nominal operation. Therefore, it is imperative that \emph{transient} component modeling and subsystem interactions be considered at the design stage to avoid costly future redesigns. Simply put, as technological advances create the need for rapid transient cooling, a new design paradigm is needed to realize next generation systems to meet these demands. <br><br>In this thesis, I develop a new design approach for TMSs called hierarchical control co-design (HCCD). More specifically, I develop a HCCD algorithm aimed at optimizing high-fidelity design and control for a TMS across a system hierarchy. This is accomplished in part by integrating system level (SL) CCD with detailed component level (CL) design optimization. The lower-fidelity SL CCD algorithm incorporates feedback control into the design of a TMS to ensure controllability and robust transient response to exogenous disturbances, and the higher-fidelity CL design optimization algorithms provide a way of designing detailed components to achieve the desired performance needed at the SL. Key specifications are passed back and forth between levels of the hierarchy at each iteration to converge on an optimal design that is responsive to desired objectives at each level. The resulting HCCD algorithm permits the design and control of a TMS that is not only optimized for steady-state efficiency, but that can be designed for robustness to transient disturbances while achieving said disturbance rejection with minimal compromise to system efficiency. Several case studies are used to demonstrate the utility of the algorithm in designing systems with different objectives. Additionally, high-fidelity thermal modeling software is used to validate a solution to the proposed model-based design process. <br>

An investigation was conducted into the feasibility of using an unconventional flight technique, asymmetric flight, to improve overall efficiency of solar aircraft. In this study, asymmetric flight is defined as steady level flight in a non-wings-level state in- tended to improve solar incidence angle. By manipulating aircraft orientation through roll angle, solar energy collection is improved but aerodynamic efficiency is worsened due to the introduction of additional trim drag. A point performance model was devel- oped to investigate the trade-off between improvement in solar energy collection and additional drag associated with asymmetric flight. A mission model with a focus on aircraft orbits was then developed via integration of the point performance model over a set of discrete points. It is shown that there is a non-zero bank angle where optimal net power is achieved for a given aircraft orientation, flight condition, and sun position. The study also shows that there is improvement in overall efficiency over conventional flight for various orbit shapes and winds aloft. This indicates that there is potential value in not only flight path planning, but also in orientation planning for solar aircraft.

<p> Within recent years, there has been a renewed interest in developing data-driven learning based algorithms for solving longstanding challenging control problems. This interest is primarily motivated by the availability of ubiquitous data and an increase in computational resources of modern machines.  However, there is a prevailing concern on the lack of provable performance guarantees on data-driven/model-free learning based control algorithms. This dissertation focuses the following key aspects: i) with what facility can state-of-the-art learning-based control methods eke out successful performance for challenging flight control applications such as aerobatic maneuvering?; and ii) can we leverage well-established tools and techniques in control theory to provide some provable guarantees for different types of learning-based algorithms?  </p> <p>To these ends, a deep RL-based controller is implemented, via high-fidelity simulations, for Fixed-Wing aerobatic maneuvering. which shows the facility with which learning-control methods can eke out successful performances and further encourages the development of learning-based control algorithms with an eye towards providing provable guarantees.<br> </p> <p>Two learning-based algorithms are also developed: i) a model-free algorithm which learns a stabilizing optimal control policy for the bilinear biquadratic regulator (BBR) which solves the regulator problem with a biquadratic performance index given an unknown bilinear system; and ii) a model-free inverse reinforcement learning algorithm, called the Model-Free Stochastic inverse LQR (iLQR) algorithm, which solves a well-posed semidefinite programming optimization problem to obtain unique solutions on the linear control gain and the parameters of the quadratic performance index given zero-mean noisy optimal trajectories generated by a linear time-invariant dynamical system. Theoretical analysis and numerical results are provided to validate the effectiveness of all proposed algorithms.</p>

<p> Motivated by the increasing need to monitor safety-critical systems subject to uncer-<br> tainties, a novel set-membership approach is proposed to estimate the state of a dynamical<br> system with unknown-but-bounded exogenous inputs. By fully utilizing the system struc-<br> tural information, the proposed algorithm can address both computational efficiency and<br> estimation accuracy without requiring restrictive conditions on the system. Particularly,<br> the system is first decomposed into the strongly observable subsystem and the weakly un-<br> observable subsystem. To make full use of the subsystem’s properties, a set-membership<br> observer based on the unknown input observer and an ellipsoidal set-membership observer<br> are designed for the two subsystems, respectively. Then, the resulting set estimates from<br> each subsystem are fused and transformed to obtain the set estimate for the original system,<br> which is guaranteed to bound the actual system state. The conditions for the boundedness<br> of the proposed set estimate are discussed, and the proposed set-membership observer is also<br> tested numerically using illustrative examples.</p>

Multidisciplinary Design Optimization (MDO) is an area in engineering design which has been growing rapidly in terms of applications in the last few decades, aircraft design being no exception to that. The application of MDO to aircraft and more specifically, wing design, presents many challenges, since disciplines like aerodynamics and structures have to be combined and interact. The level to which this interaction is implemented depends only on how much one is willing to pay in terms of computational cost. The objective of the current work is therefore to develop a simplified MDO tool, suitable for the preliminary design of aircraft wings. At the same time, versatility in the definition of optimization problems (in terms of design variables, constraints and objective function) is given great attention. At the same time, modularity will ensure that this framework is upgradeable with higher-fidelity and/or more capable modules. The disciplines that were chosen for interaction were aerodynamics and structures/ aeroelasticity, though more data can be extracted from their results in order to perform other types of analyses. The aerodynamics module employs a Vortex Lattice code developed specifically for the current implementation of the tool. The structural module is based on Equivalent Plate model theory. The fluid structure interaction is simply one-way, wherein the aerodynamics loads are passed on to the structural analyzer for computation of the static deformation. Semi-empirical relations are then used to estimate the flutter speed. The optimizer, which controls the activity of the other modules, makes use of a gradient based algorithm (Sequential Quadratic Programming) to search for a local minimum of a user defined objective function. Among the myriad of MDO strategies available, two are chosen to exemplify the modularity of the tool developed: Multidiscipline Feasible (MDF) and Sequential Optimization (SO), and their results are compared. Several case studies are analyzed to cover a broad spectrum of the capabilities of the framework. Because user interaction is of prime concern in design optimization, a graphical interface (GUI) of the tool is presented. Its advantages in terms of the set up of optimization problems and post-processing of results are made clear. In conclusion, some topics for future work regarding the expansion and improvement of the features of the application are noted.