The primary objective of this thesis is to develop a framework to compare the performance of fixed-wing aircraft, airships, and the rotary-wing aircraft in the Martian environment and through that framework, determine which of these platforms is best suited to conduct a series of scientific investigations on Mars. Three Mars mission scenarios provide the context within which the performance of the platforms is evaluated. The mission scenarios are used to derive the performance requirements including the range and flight path to be covered, the altitude at which the platforms fly, and the scientific investigations to be performed along with the associated scientific instrumentation to be carried as payload. Existing platform designs are used for the purpose of this comparative study and are modified depending on specific mission requirements. A set of weighted performance metrics, including the gross takeoff mass, power required, manoeuvrability, and complexity, serves as a common basis for comparing the performance of the three aerial platforms. The results of this comparative study indicate that the airship is best suited for all mission scenarios considered due to its simplicity and high degree of manoeuvrability. However, it is important to note that a series of subjective design choices with respect to platform speed and available power were made that significantly impact the overall performance of the platforms. Altering these design choices as well as the mission requirements could result in a different platform being best suited for each Mars mission. For instance, increasing the cruising velocity of the fixed-wing aircraft may allow its dimensions to be scaled down thereby reducing the complexity and making it a more competitive platform for long-range missions. In addition, for short-range missions that do not require a high degree of manoeuvrability but where the gross takeoff mass and complexity are more important factors, the rotary-wing aircraft becomes the best option.

Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Includes bibliographic references (p.105-107).

No description available.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Aerostats and Stratolites could play a major role in expanding current satellite and other technologies in the near future. A study was made on the development of aerostat platforms and the current state of Stratolite development. The aim was to develop an airship system that is capable of maintaining a specific position regardless of the presence of wind. The various applications of such a geostationary platform are discussed. A dynamic model of an airship was developed and a simulation was implemented in software. This was done to study the possibility of developing aerostats like these. A tethered airship system was developed and built to demonstrate that it is possible to control the position of an airship. The airship system uses current technology in an unique combination to fulfil the requirement of remaining stationary despite the influence of wind. Various control system design techniques were used to implement the controllers. Linear models of the airship system were identified practically and used to design the controllers. The controllers were tested in simulation as well as practically and the results of these tests are given. It was concluded that there exists potential for the development of Stratolite systems, although there exists a fair amount of challenges and obstacles that would need to be overcome before this technology could be implemented. / AFRIKAANSE OPSOMMING: Aerostats en Stratolites kan ’n besondere rol speel in die uitbreiding van huidige sateliet- en ander aardwaarnemingstoepassings. ’n Studie is gemaak oor die ontwikkeling van Aerostat platforms en die huidige stand van Stratolite ontwikkeling. Die mikpunt was om ’n lugskipstelsel te ontwikkel wat in staat is om ’n spesifieke posisie te handhaaf ten spyte van die invloed van wind. Die verskeidenheid van toepassings, waarvoor so ’n geostasionêre platform gebruik kan word, word genoem. ’n Dinamiese model van ’n lugskip is ontwikkel en die stelsel is in sagteware gesimuleer. Dit is gedoen om die moontlikheid te ondersoek om sulke Aerostats in die toekoms te ontwikkel. ’n Lugskipstelsel, wat aan die grond geanker word met ’n kabel, is ontwerp en gebou. Die stelsel is gedemonstreer en daar is bewys dat dit moontlik is om die posisie van die lugskip te beheer. Die lugskip gebruik huidige tegnologie wat in ’n unieke kombinasie saamgevoeg is om te illustreer dat dit moontlik is vir die lugskip om stasionêr te bly ten spyte van wind. Verskeie beheerstelsels ontwerptegnieke is gebruik om die beheerders mee te implementeer. Lineêre modelle van die lugskip is prakties geïdentifiseer en is gebruik om die beheerders te ontwerp. Die lugskip se beheerders is in simulasie sowel as prakties getoets en die resultate van hierdie toetse word gegee. Die projek bevestig dat daar ’n potensiaal bestaan vir die praktiese ontwikkeling van Stratolite stelsels. Daar is egter ’n hele paar uitdagings en probleme wat eers uit die weg geruim sal moet word, voordat hierdie tegnologie ’n alledaagse werklikheid sal word.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / A real time attitude and heading reference system (AHRS) was successfully implemented for use on an airship. The AHRS was tested on board a small airship (blimp) with real data supplied from the inertial measurement unit and GPS receiver. The inertial measurement unit was built with lower grade sensors, resulting in significant reductions in component cost. To ensure accurate navigation results, the high rate inertial measurements were complemented with low rate GPS velocity and position updates in an extended Kalman filter configuration. A study was made of various Kalman filter configurations, especially the possibility of splitting a big Kalman filter into smaller Kalman filters. It was found that the best trade-off between accuracy and processing power was achieved by having two smaller Kalman filters running in sequence. The first extended Kalman filter estimates the attitude of the airship, while the second extended Kalman filter estimates the velocity and position of the airship. The two smaller Kalman filters were implemented on an onboard computer to provide real time estimates of the attitude, velocity and position of the airship.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In recent years, the use of airships has become popular for observation purposes since they provide a cost effective alternative to other aircraft. For this project a lateral and longitudinal flight control system are required for waypoint navigation flight of an 8m long, non-rigid airship. The airship’s actuators include a rudder, elevator and a propulsion system which can be vectored longitudinally. Two airship models are evaluated for this project. A chosen model is linearised and a modal analysis is done. The modal analysis is compared to a previous modal study done on the YEZ-2A airship and is found to compare well. Each airship mode is discussed and the linear behaviour is compared to the behaviour of the non-linear model. A fuzzy logic controller design approach was undertaken for the design of speed, heading and height controllers. These non-linear controllers were designed for the non-linear model, due to the following reasons: Fuzzy logic controllers show tolerance to model inaccuracies. Complexity of design is simple. Controllers can be adjusted intuitively. Fuzzy logic controllers can be combined with conventional control techniques. Simulation results showed adequate lateral and longitudinal performance, even when subjected to light wind conditions and disturbances. The inertial measuring unit implemented in a previous project is used and additional hardware is designed and implemented for the control of the airship’s actuators. Several improvements are made to the groundstation software to allow for activation of different controllers as well as for setting up the desired flight plan. The controller performance is tested through flight tests and shows adequate performance as well as controller potential. Although further work is still required for improving the controllers’ performance, this thesis acts as a platform for future research. / AFRIKAANSE OPSOMMING: In die afgelope paar jaar het die gebruik van die lugskepe gewild geword vir waarnemings doeleindes aangesien dit ’n koste effektiewe alternatief vir ander lugvaartuie bied. In hierdie projek word ’n laterale en longitudinale beheerstelsel benodig vir merker navigasie vlugte met ’n 8m lang, nierigiede lugskip. Die lugskip se aktueerders sluit in ’n rigtingroer, hoogteroer asook ’n aandrywing stelsel wat oorlangs gestuur kan word. Vir hierdie projek is twee lugskip modelle geïmplementeer. Die gekose model is gelineariseer en ’n modale analise is gedoen. Die modale analise is met ’n vorige modale studie vir die YEZ-2A lugskip vergelyk en wys soortegelyke linieêre gedrag. Die lugskip modusse is bespreek en die linieêre gedrag word met die gedrag van die nie-linieêre model vergelyk. Daar is op ’n fuzzy logiese beheerder ontwerp besluit vir die ontwerp van spoed, rigting en hoogte beheerders. Hierdie nie-linieêre beheerders is ontwerp vir die nie-linieêre model a.g.v. die volgende redes: Fuzzy logiese beheerders toon toleransie vir modellering of meetfoute. Kompleksiteit van die ontwerp is eenvoudig. Beheerders kan intuïtief aangepas word. Fuzzy logiese beheerders kan met konvensionele beheertegnieke gekombineer word. Simulasie resultate toon voldoende werkverrigtinge, selfs in die teenwoordigheid van ligte wind sowel as ander versteurings. Die inersiële metings eenheid, wat geïmplementeer is in ’n vorige projek, is gebruik en addisionele hardeware vir die beheer van die lugskip is aktueerders is ontwerp en geïmplementeer. Talle verbeterings is aangebring aan die grondstasie sagteware vir die aktiveer van die beheerders sowel as die uitleg van die gekose vlugplan. Die beheerders se werksverrigtinge is getoets gedurende vlugtoetse en toon voldoende beheer vermoë sowel as beheerder potensiaal. Alhoewel verdere werk steeds nodig is vir die verbetering van die beheerders, dien hierdie tesis as ’n platform vir toekomstige navorsing.

The field of man portable UASs (Unmanned Aerial Systems) is currently a key area in improving the fielded warrior's capabilities. Pressurized aerostructures that can perform with similar results of solid structures can potentially change how this objective may be accomplished now and in the future. Construction with high density polymers and other composites is currently part of active inflatable vehicle research. Many shape forming techniques have also been adapted from the airship and balloon manufacturing industry. Additional research includes modeling techniques so that these vehicles may be included in simulation packages. A flight dynamics simulation with reduced-order aeroelastic effects derived with Lagrangian and Eulerian dynamics approaches were developed and optimized to predict the behavior of inflatable flexible structures in small UASs. The models are used to investigate the effects of significant structural deflections (warping) on aerodynamic surfaces. The model also includes compensation for large buoyancy ratios. Existing literature documents the similarity in structural dynamics of rigid beams and inflatable beams before wrinkling. Therefore, wing bending and torsional modes are approximated with the geometrically exact ntrinsic beam equations using NATASHA (Nonlinear Aeroelastic Trim And Stability for HALE Aircraft) code. An approach was also suggested for inclusion of unique phenomena such as wrinkling during flight. A simplified experimental setup will be designed to examine the most significant results observed from the simulation model. These methods may be suitable for specifying limits on flight maneuvers for inflatable UASs.

A concessão de créditos garantidos pelo próprio ativo financiado responde por substancial fatia da atividade creditícia e permite o acesso a financiamentos de devedores mais arriscados com taxas de juros reduzidas. O financiamento de aeronaves é um nicho especialmente dependente desse tipo de estrutura e a investigação de um indicador que consolide os parâmetros quantitativos relevantes para sua análise amplia a robustez e organiza a subjetividade dos processos de tomada de decisão. Esse trabalho ilustra o desenvolvimento do indicador time to loss como um desdobramento prático dos fundamentos implícitos na formulação de perda esperada do Comitê de Basileia. São evidenciadas as três curvas que caracterizam a estimação do tempo para a perda: a exposição devida ao inadimplir, o valor residual da aeronave e os custos e encargos no período de recuperação do crédito. Calculado o indicador para o caso base de estudo, o trabalho explora ainda alternativas para a construção de escalas de referência que qualifiquem sua interpretação. Testes e estudos continuados são propostos como referência para futuras pesquisas e desenvolvimento do tema. / The concession of credit secured by the financed asset itself accounts for a substantial share of lending activity and allows access to finance for riskier borrowers with lower interest rates. The aircraft financing is a typical niche dependent on this type of structure and the investigation of an index that consolidates relevant quantitative parameters for its analysis extends the robustness and organizes the subjectivity of the decision-making process. This work illustrates the development of the indicator time to loss as a practical deployment of the implicit foundations in the expected loss formulation of the Basel Committee. Three curves are evidenced featuring the estimation of the time to loss: exposure due to defaults, the residual value of the aircraft and the cost and burden on the credit recovery period. After calculating the time to loss indicator for the base case study, the work also explores ways to build a reference scale which qualify its interpretation. Tests and continued studies are proposed as reference theme for future research and development. / Dissertação (mestrado) - Programa de Pós-Graduação e Pesquisa em Administração e Economia, Faculdades Ibmec, Rio de Janeiro, 2015. / Bibliografia: p. 76-77

Made available in DSpace on 2016-04-28T14:16:34Z (GMT). No. of bitstreams: 1 Erivelton Alves Bizerra.pdf: 8926443 bytes, checksum: 178bf86156f6b57ad9075f66503b1aac (MD5) Previous issue date: 2008-10-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Alberto Santos Dumont (1873-1932) is well known in Brazil and France for his pioneer contributions to the development of the airplane. However, before that, he also helped to develop the technique of balloon flight, obtaining important results of directed flight using motorized airships. This works analyses his contribution to this field. This dissertation presents, first, an historical account of the invention of balloons, from the early Chinese flying lights to the introduction of hot-air and hydrogen balloons in Europe, in the 18th century. Next, this work analyses the issue of balloon flight control. After the first manned flights, in 1783, there was a strong interest for this invention and there were several proposals of controlling its flight. The first attempts of flying motorised balloons, which attained a moderate success, were made in 1852, using a heavy steam machine. Other attempts were made afterwards, using several kinds of motors (including electrical ones), but they did not attain practical results. In the late 19th century, Santos Dumont began to develop airships driven by internal combustion engines (such as those used by automobiles) and obtained good results. In 1901 he was awarded the Deutsch de la Meurthe Prize, when he demonstrated the control of a motorised balloon that was able to make a flight round the Eiffel Tower. Finally, this dissertation analyses Santos Dumont s scientific and technical knowledge, as well the technical difficulties involved in the control of airships, at that time / Alberto Santos Dumont (1873-1932) é muito conhecido, no Brasil e na França, por seus trabalhos pioneiros sobre aviação, mas também desenvolveu, antes disso, a técnica de vôo em balões, obtendo importantes resultados na dirigibilidade com aparelhos dotados de motor. Este trabalho analisa sua contribuição neste campo. Esta dissertação apresenta primeiramente um histórico da invenção dos balões, desde as luzes voadoras chinesas até a introdução de balões de ar quente e de hidrogênio na Europa, no século XVIII. Em seguida, a dissertação analisa a história da dirigibilidade dos balões. Logo após os primeiros vôos tripulados, em 1783, surgiu um enorme interesse pelo invento e foram propostas formas de proporcionar-lhe dirigibilidade. As primeiras tentativas, com algum grau de sucesso, de balões dotados de motores ocorreram em 1852, utilizando uma máquina a vapor. Houve depois algumas poucas tentativas, utilizando motores de vários tipos (inclusive elétricos), mas não foram obtidos bons resultados. Nos últimos anos do século XIX, Santos Dumont iniciou o desenvolvimento de balões movidos por motores de combustão interna (como os de automóveis) e conseguiu bons resultados. Em 1901, obteve o Prêmio Deutsch de la Meurthe, demonstrando o controle de um balão motorizado que contornou a Torre Eiffel. Por fim, a dissertação analisa os conhecimentos científicos e técnicos de Santos Dumont, bem como as dificuldades técnicas que era necessário superar para conseguir controlar o vôo dos balões, na época