Development of modern aircraft has become more and more expensive and time consuming. In order to minimize the development cost, an improvement of the conceptual design phase is needed. The desired goal of the project is to enhance the functionality of an in house produced framework conducted at the department of machine design, consisting of parametric models representing a large variety of aircraft concepts. The first part of the work consists of the construction of geometric aircraft control surfaces such as flaps, aileron, rudder and elevator parametrically in CATIA V5. The second part of the work involves designing and simulating an Inverse dynamic model in Dymola software. An Excel interface has been developed between CATIA and Dymola. Parameters can be varied in the interface as per user specification; these values are sent to CATIA or Dymola and vice versa. The constructed concept model of control surfaces has been tested for different aircraft shapes and layout. The simulation has been done in Dymola for the control surfaces.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2015. / Currently non-destructive testing techniques for composite aircraft structures are disadvantaged when compared to online Structural Health Monitoring (SHM) systems that monitor the structure while in-service and give real time data. The present research work looks at developing a protocol for online structural health monitoring of a UAV wing structure using PVDF film sensors, especially including the monitoring of structural changes caused by defects. Different types of SHM techniques were studied in relation to carbon fibre composites. Laminate composite make-up and manufacturing process was investigated and vacuum infusion process was used to manufacture the samples that resemble the Guardian II wing structure, then the three-point bending test was used to determine the material properties. Digital Shearography was employed as a stationery non-destructive technique to determine the sensor to structure attachment, type and position of defects that affect the state of performance. Finite Element Analysis (FEA) was done using ANSYS Workbench which served as a modelling tool using a drawing imported from Solid-works. Experimental investigation was done using PVDF sensor embedded on the surface of the sample in a cantilever setup and a vertical Vernier scale to measure the deflection due to impact and vibration loading. A Fluke-View oscilloscope was used as a data logger when the measurement of the output voltage and the natural frequency were recorded. The techniques of using FEA and experimental investigation were then compared. The findings of this study showed that the PVDF sensor is suitable for condition monitoring of a UAV wing structure.

Recently, the wavy leading edge airfoils, inspired by the humpback whale´s flipper, have been investigated, as flow control mechanisms, at low Reynolds numbers in order to improve aerodynamic performance in this particular flow regime. The overall aim of this work is to investigate the airfoil geometric effects on wavy leading edge phenomena in the low Reynolds number regime. Experimental investigations were carried out correlating force measurements with mini-tuft and oil visualizations in order to understand the airfoil thickness effects on wavy leading edge phenomena. Three sets of airfoil thickness were tested (NACA 0012, NACA 0020 and NACA 0030), each set consisting of smooth plus three wavy configurations (A=0.11c, ?=0.40c; A=0.03c, ?=0.40c and A=0.03c, ?=0.11c); Reynolds number was varied between 50,000 and 290,000. The results present many findings that were not possible in previous studies due the fact that these investigations were constrained to specific geometries and/or flow conditions. At higher Reynolds number, the decrease in airfoil thickness leads the airfoils to leading edge stall characteristics causing the lowest aerodynamic deterioration for the thinnest wavy airfoil as compared to smooth configuration in the pre-stall regime. In addition, the results show impressive tubercle performance in the lowest Reynolds number. For any tubercle geometry and airfoil thickness, the wavy leading edge airfoils present higher maximum lift values as compared to smooth configurations showing an unprecedented increase in performance for a full-span model tested in the literature. The flow visualizations present two flow mechanisms triggered by secondary flow: three-dimensional laminar separation bubbles and vortical structures. Regarding three-dimensional laminar bubbles, the results confirm some of the few previous experimental and numerical studies, and presents for the first time these structures as a very efficient flow control mechanism in the post-stall regime justifying the impressive increase in maximum lift in the lowest Reynolds number. Besides that, two characteristics of laminar bubbles, \"tipped-bubbles\" and \"elongated-bubbles\", are identified with different effects in the pre-stall regime. This thesis presents higher tubercle performance for thinner airfoils (NACA 0012) and/or lower Reynolds number conditions (Re=50,000) showing clearly that an optimum performance lead the \"tubercles\" to operate under conditions of leading edge flow separation conditions. Therefore, a design space for tubercles conducted to leading edge stall characteristics confirming the hypothesis of Stanway (2008) eight years before. / Recentemente, aerofólios com bordo de ataque ondulados, inspirados na nadadeira da baleia jubarte, tem sido investigados como mecanismo de controle de escoamento para baixo número de Reynolds com a finalidade de se aumentar o desempenho aerodinâmico neste específico regime de escoamento. O objetivo geral deste trabalho é investigar os efeitos geométricos do aerofólio nos fenômenos do bordo de ataque ondulado na condição de baixo número de Reynolds. Investigações experimentais foram realizadas correlacionando medições de forças com visualizações de lã e óleo a fim de compreender os efeitos da espessura do aerofólio sobre os fenômenos de bordo de ataque ondulado. Três conjuntos de espessura de aerofólios foram testados (NACA 0012, NACA 0020 e NACA 0030) na faixa de número de Reynolds entre 50,000 e 290,000, onde cada conjunto tem um aerofólio liso e três ondulados (A = 0.11c, ? = 0.40c; A = 0.03c, ? = 0.40c e A = 0.03c, 0.11c ? =0.11c). O dados experimentais mostram importantes resultados que não foram possíveis em estudos anteriores devido às investigações serem restritas à geometria ou/e condição de escoamento específicas. O resultados de medida de força mostram que a diminuição da espessura do aerofólio conduz às características de separação de escoamento de bordo de ataque que causam menor deterioração aerodinâmica nos aerofólios ondulados finos quando comparados aos lisos no regime de pré-stall. Além disso, os resultados mostram um desempenho destacado do bordo de ataque ondulado para condição de menor número de Reynolds. Em quaisquer espessuras de aerofólio, os bordos ondulados apresentam valores de sustentação máxima maiores quando comparado aos aerofólios lisos mostrando assim resultado inédito na literatura para modelos ondulados bi-dimensionais. As visualizações de óleo evidenciaram dois mecanismos de controle de escoamento desencadeadas pelo escoamento secundário: bolhas de separação laminar tridimensionais e estruturas vorticais. Os resultados confirmam alguns poucos estudos experimentais e numéricos anteriores relacionadas com bolhas tridimensionais, e apresenta pela primeira vez estas estruturas como um mecanismo muito eficiente de controle de escoamento em regime de pós-stall justificando o aumento de máxima sustentação para o menor número de Reynolds. Adicionalmente, foram identificadas duas estruturas de bolhas tridimensionais nomeados aqui como \"bolhas com pontas\" e \"bolhas alongadas\" que causam distintos efeitos no regime de pré-stall. Esta tese apresenta como resultado maior desempenho para aerofólios ondulados com menor espessura (NACA 0012) e/ou para condições de menor número de Reynolds (Re=50,000)mostrando claramente que estas características levam as ondulações a operarem em condições de stall de bordo de ataque assim tendo um desempenho superior. Portanto, um espaço de projeto para tubérculos conduz às características de stall de bordo de ataque confirmando a suposição de Stanway (2008) oitos anos antes.

Made available in DSpace on 2016-04-15T21:44:14Z (GMT). No. of bitstreams: 2 Marcelo Silva Oliveira1.pdf: 3584802 bytes, checksum: 6c449bc2868b11debc6abaf00c790c95 (MD5) Marcelo Silva Oliveira2.pdf: 1736464 bytes, checksum: 7b5ab81c163e2f6fa851d4a953bba239 (MD5) Previous issue date: 2010-08-25 / The present work is the matureness of the research for new primary/basic trainer aircraft requirements to substitute the current Brazilian made Universal Neiva T-25C. These aircrafts are at the end of their service life with the Brazilian Air Force and, at the moment, there are no substitutes to act as a replacement trainer to the Braziliam Air Force Academy (AFA) cadets. In the search for requirements and standards to define the characteristics of the new trainer, the author took advantage of a Systems Engineering analysis methodology with which, under a more holistic and macro point - of - view, he highlighted three main aspects of the instruction system: man, machine and method. The work begins with the definition of the interfaces among engineering, design and architecture; after that there is an exposition of the objectives and a national private (civilian) and military flight training programs review, in order to emphasize the problems and build up the hypotheses and the thesis. After the analysis and comparison of the Brazilian system with the USAF (United States Air Force) program, a change in the Brazilian flight training program was discussed, which would start with an initial flight instruction phase using light aircraft. This new revised program would contribute for the reduction of the attrition number (elimination of cadets not suited to flying in the training process) and would save hundreds of thousands of reais per year of the tax payers money. A research was done with the Brazilian Air Force Academy instructors, aiming to reveal the real facts, problems and characteristics for a hypothetic brand new trainer aircraft. There is still an analysis of the systems engineering process and its role in the aeronautical industry. In the final part of this work, a comparative study of commercially available trainer aircraft can be found. The trade study aims to establish a scenario for the changes in the present training system and the adoption of the light aircraft as an initial trainer. The requirements extracted from the reports review and the instructor survey can help future works concerning aircraft selection or the design of a new trainer aircraft. / O presente trabalho é o amadurecimento da pesquisa de requisitos para o projeto de uma aeronave de treinamento primário/básico, para substituir os atuais treinadores de fabricação nacional Neiva T-25C Universal. Estas aeronaves estão no término de suas vidas operacionais e, até o presente momento, não há ainda uma aeronave escolhida para dar continuidade à tarefa de instrução dos cadetes na Academia da Força Aérea Brasileira (AFA). Na busca por requisitos e normas para a definição das características do novo treinador, o autor acabou por utilizar uma metodologia de análise, emprestada da Engenharia de Sistemas, onde, sob uma ótica mais holística e macro, destacou três principais aspectos do sistema de instrução: Homem, Máquina e Método. O trabalho inicia-se com a definição das interfaces entre: engenharia, design e arquitetura, seguindo a uma exposição dos objetivos do trabalho e uma revisão do processo de pilotagem civil e militar neste país, procurando enfatizar os problemas, para a construção das hipóteses e da tese. Foi discutida, após análise e comparação do sistema brasileiro com o processo de instrução da USAF (Força Aérea dos Estados Unidos), a mudança no programa de instrução brasileiro, que passaria a contar com uma fase inicial de instrução utilizando-se aeronaves leves, que além de contribuir para a diminuição do número de atrito desligamentos dos cadetes não adaptados para a tarefa do vôo), economizaria aos cofres públicos uma centena de milhares de reais por ano. Foi realizada uma pesquisa com os instrutores da AFA, visando saber das restrições, problemas e características ideais para o cumprimento da tarefa de instrução na força aérea brasileira. Há ainda uma revisão do processo de engenharia de sistemas e seu emprego na indústria aeronáutica. Na parte final do volume, pode ser encontrada um estudo comparativo entre aeronaves de instrução disponíveis comercialmente no mercado. A comparação se faz com o objetivo de estabelecer um cenário para a mudança no sistema de treinamento e a inclusão do novo vetor de instrução. Foram gerados requisitos gerais com relação à configuração, características e desempenho em voo, que podem servir para embasar o processo de seleção ou projeto de uma nova aeronave de instrução.

Aircraft structural layout concept design at Saab Aeronautics utilize thickness optimizationto evaluate astructural layout concept. The thickness values can be used to compare conceptsto each other,and the bestonecan be further developed. Today, most ofthe creation and evaluation of structural layout concepts is manual work. Therefore, there is an ongoing investigation on how to implement design automation to reduce this manual and repetitive work. The investigationaims to achieve rapid exploration of the design space to find a good base for a new aircraft development. This includes investigating how the synchronization between a structural layout model (SLM) and a global finite element model (GFEM) can be improved. This thesis contributes to the investigation by exploring the possibilities to implement design automation in the creation of the SLM regarding the fuselage structure. Further, exploring the implementation of design automation in the creation of the GFEM to enable automatic evaluation of concepts. The thesis also explores how the synchronization between the models can be improved. To structure the thesis work, the software development methodologies of MOKA and RAD weremodified and combined. The execution of the thesis was carried out in the software of 3DEXPERIENCE, particularly using the applications CATIAand SIMULIA. This thesis work resulted in a methodfor developing and evaluating aircraft structure concept designs with design automation. The new method includes two models with corresponding scripts. The first model developed is a tool for a conceptualdesignerthat enables the creation of aircraft fuselage SLM from user defined inputs. The second model is generated by script which results in a GFEM with a direct connection to the SLM. To conclude, the developed method enables a faster iteration work of fuselage structural concept designs compared to the current method. The detail level is lower but more consistent and uniform. The GFEM was not able to fulfil its purpose in the developed method due to time limits and software limitations. However, the synchronization between the SLM and GFEM was implemented successfully and contained all critical elements.

The objective of this research is to examine how to design low-noise transport aircraft using Multidisciplinary Design Optimization (MDO). The subject is approached by designing for low-noise both implicitly and explicitly. The explicit design approach involves optimizing an aircraft while explicitly constraining the noise level. An MDO framework capable of optimizing both a cantilever wing and a Strut-Braced-Wing (SBW) aircraft was developed. The framework employs aircraft analysis codes previously developed at the Multidisciplinary Design and Analysis (MAD) Center at Virginia Tech (VT). These codes have been improved here to provide more detailed and realistic analysis. The Aircraft Noise Prediction Program (ANOPP) is used for airframe noise analysis. The objective is to use the MDO framework to design aircraft for low-airframe-noise at the approach conditions and quantify the change in weight and performance with respect to a traditionally designed aircraft. The results show that reducing airframe noise by reducing approach speed alone, will not provide significant noise reduction without a large performance and weight penalty. Therefore, more dramatic changes to the aircraft design are needed to achieve a significant airframe noise reduction. Another study showed that the trailing-edge (TE) flap can be eliminated, as well as all the noise associated with that device, without incurring a significant weight and performance penalty. To achieve approximately 10 EPNdB TE flap noise reduction the flap area was reduced by 82% while the wing reference area was increased by 12.4% and the angle of attack increased from 7.6 degrees to 12.1 degrees to meet the required lift at approach. The wing span increased by approximately 2.2%. Since the flap area is being minimized, the wing weight suffers only about a 2,000 lb penalty. The increase in wing span provides a reduction in induced drag to balance the increased parasite drag due to a lower wing aspect ratio. As a result, the aircraft has been designed to have minimal TE flaps without any significant performance penalty. If noise due to the leading-edge (LE) slats and landing gear are reduced, which is currently being pursued, the elimination of the flap will be very significant as the clean wing noise will be the next 'noise barrier'. Lastly, a comparison showed that SBW aircraft can be designed to be 10% lighter and require 15% less fuel than cantilever wing aircraft. Furthermore, an airframe noise analysis showed that SBW aircraft with short fuselage-mounted landing gear could have similar or potentially a lower airframe noise level than comparable cantilever wing aircraft. The implicit design approach involves selecting a configuration that supports a low-noise operation, and optimizing for performance. A Blended-Wing-Body (BWB) transport aircraft has the potential for significant reduction in environmental emissions and noise compared to a conventional transport aircraft. A BWB with distributed propulsion was selected as the configuration for the implicit low-noise design in this research. An MDO framework previously developed at the MAD Center at Virginia Tech has been refined to give more accurate and realistic aircraft designs. To study the effects of distributed propulsion, two different BWB configurations were optimized. A conventional propulsion BWB with four pylon mounted engines and two versions of a distributed propulsion BWB with eight boundary layer ingestion inlet engines. A 'conservative' distributed propulsion BWB design with a 20% duct weight factor and a 95% duct efficiency, and an 'optimistic' distributed propulsion BWB design with a 10% duct weight factor and a 97% duct efficiency were studied. The results show that 65% of the possible savings due to 'filling in' the wake are required for the 'optimistic' distributed propulsion BWB design to have comparable $TOGW$ as the conventional propulsion BWB, and 100% savings are required for the 'conservative' design. Therefore, considering weight alone, this may not be an attractive concept. Although a significant weight penalty is associated with the distributed propulsion system presented in this study, other characteristics need to be considered when evaluating the overall effects. Potential benefits of distributed propulsion are, for example, reduced propulsion system noise, improved safety due to engine redundancy, a less critical engine-out condition, gust load/flutter alleviation, and increased affordability due to smaller, easily-interchangeable engines. / Ph. D.

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Today's modern aerospace systems exhibit strong interdisciplinary coupling and require a multidisciplinary, collaborative approach. Analysis methods that were once considered feasible only for advanced and detailed design are now available and even practical at the conceptual design stage. This changing philosophy for conducting conceptual design poses additional challenges beyond those encountered in a low fidelity design of aircraft. This thesis takes some steps towards bridging the gaps in existing technologies and advancing the state-of-the-art in aircraft design. The first part of the thesis proposes a new Pareto front approximation method for multiobjective optimization problems. The method employs a hybrid optimization approach using two derivative free direct search techniques, and is intended for solving blackbox simulation based multiobjective optimization problems with possibly nonsmooth functions where the analytical form of the objectives is not known and/or the evaluation of the objective function(s) is very expensive (very common in multidisciplinary design optimization). A new adaptive weighting scheme is proposed to convert a multiobjective optimization problem to a single objective optimization problem. Results show that the method achieves an arbitrarily close approximation to the Pareto front with a good collection of well-distributed nondominated points. The second part deals with the interdisciplinary data communication issues involved in a collaborative mutidisciplinary aircraft design environment. Efficient transfer, sharing, and manipulation of design and analysis data in a collaborative environment demands a formal structured representation of data. XML, a W3C recommendation, is one such standard concomitant with a number of powerful capabilities that alleviate interoperability issues. A compact, generic, and comprehensive XML schema for an aircraft design markup language (ADML) is proposed here to provide a common language for data communication, and to improve efficiency and productivity within a multidisciplinary, collaborative environment. An important feature of the proposed schema is the very expressive and efficient low level schemata. As a proof of concept the schema is used to encode an entire Convair B58. As the complexity of models and number of disciplines increases, the reduction in effort to exchange data models and analysis results in ADML also increases. / Ph. D.