Detailed design of a class I UAV for maritime surveillance

ALFAL/ENGAER 138081-J João Correia. Examination Committee: Chairperson: MGEN/ENGAER 076441-J Paulo Manuel Veloso Gonçalves Guerra (DMSA); Supervisor: MAJ/ENGAER 129905-A Luís Filipe da Silva Félix (AFA); Supervisor: CAP/ENGAER 131603-G João Vítor Aguiar Vieira Caetano (AFA); Member of the Committee: Doutor Frederico José Prata Rente Reis Afonso (IST)Esta tese destina-se ao design estrutural em materiais compósitos de um Veículo Aéreo Não-Tripulado (VANT) de classe I para vigilância marítima. A intenção de expandir o uso de VANTs pela Força Aérea Portuguesa (FAP), na ampla área de jurisdição portuguesa e nas operações internacionais, motivou a necessidade de desenvolver uma nova plataforma capaz de cumprir todos os requisitos operacionais e tecnológicos. A presente tese começa pela definição dos sistemas a bordo necessários para a aeronave, nomeadamente a carga útil, aviónicos e propulsão. O design estrutural ao nível conceptual e preliminar envolveu o planeamento da disposição geral da aeronave para atingir uma margem estática longitudinal válida e a determinação do envelope de voo com rajada para determinar o factor de carga da aeronave. Este parâmetro vai definir a caracterização das forças aerodinâmicas e inérciais para a manobra crítica de voo. O projecto detalhado da aeronave foi realizado através de modelação em Desenho Assistido por Computador (CAD) com o objetivo de minimizer o peso estrutural. O design foi confirmado por uma análise numérica de tensões através de uma Análise de Elementos Finitos (FEA) e foi alcançada convergência para os valores obtidos de tensão e de deslocamento. O design desenvolvido é capaz de suportar a condição de carga crítica sem falha estrutural. A configuração da aeronave com todos os sistemas a bordo apresenta um peso dentro dos limites para a respectiva classe e uma autonomia de oito horas para operações de vigilância marítima. O design desenvolvido pode apresentar outras configurações, e tem uma autonomia máxima de doze horas.This thesis concerns the composite structural design of a class I Unmanned Aerial Vehicle (UAV) for maritime surveillance. The intention to expand the UAV use by Portuguese Air Force (FAP), over the broad area of Portuguese jurisdiction and in international operations, motivated the need to develop a new platform capable to fulfil all the operational and technological requirements. This thesis starts by defining all the necessary onboard systems for the aircraft, namely the payload, avionics and propulsion. The conceptual and preliminary structural design involved planning the general layout to achieve a valid longitudinal static margin and determining the aircraft flight envelope with gust loads to determine the design load. This design driver set the aerodynamic and inertial load characterization of the critical flight manoeuvre. The aircraft detailed design was performed through Computed Aided Design (CAD) modelling with the objective of minimizing the structural weight. The design was endorsed by a numerical stress analysis through a Finite Element Analysis (FEA) and achieved convergence for the stress and displacement results. The developed design withstands the critical load condition without failure of the structure. The aircraft configuration with full payload presents a weight within its class range and an endurance of eight hours for maritime surveillance operations. The implemented design supports other configurations, presenting an endurance up to twelve hours.N/

Using learning from demonstration to enable automated flight control comparable with experienced human pilots

Modern autopilots fall under the domain of Control Theory which utilizes Proportional Integral Derivative (PID) controllers that can provide relatively simple autonomous control of an aircraft such as maintaining a certain trajectory. However, PID controllers cannot cope with uncertainties due to their non-adaptive nature. In addition, modern autopilots of airliners contributed to several air catastrophes due to their robustness issues. Therefore, the aviation industry is seeking solutions that would enhance safety. A potential solution to achieve this is to develop intelligent autopilots that can learn how to pilot aircraft in a manner comparable with experienced human pilots. This work proposes the Intelligent Autopilot System (IAS) which provides a comprehensive level of autonomy and intelligent control to the aviation industry. The IAS learns piloting skills by observing experienced teachers while they provide demonstrations in simulation. A robust Learning from Demonstration approach is proposed which uses human pilots to demonstrate the task to be learned in a flight simulator while training datasets are captured. The datasets are then used by Artificial Neural Networks (ANNs) to generate control models automatically. The control models imitate the skills of the experienced pilots when performing the different piloting tasks while handling flight uncertainties such as severe weather conditions and emergency situations. Experiments show that the IAS performs learned skills and tasks with high accuracy even after being presented with limited examples which are suitable for the proposed approach that relies on many single-hidden-layer ANNs instead of one or few large deep ANNs which produce a black-box that cannot be explained to the aviation regulators. The results demonstrate that the IAS is capable of imitating low-level sub-cognitive skills such as rapid and continuous stabilization attempts in stormy weather conditions, and high-level strategic skills such as the sequence of sub-tasks necessary to takeoff, land, and handle emergencies

Aerodynamic detailed design of an Unmanned Aerial Vehicle with VTOL capabilities

ALF/ENGAER 139424-L Vasco Luís Martins Ferreira Coelho. Examination Committee: Chairperson: BGEN/EngEl 119923-E Rui Fernando da Costa Ferreira; Supervisor: MAJ/EngAer 131603-G Joao Vítor Aguiar Vieira Caetano, Dr. Frederico José Prata Rente Reis Afonso; Member of the Committee: Prof. Dr. Afzal SulemanEsta tese está integrada num projeto de desenvolvimento de um veículo aéreo não tripulado capaz de efetuar descolagem e aterragem vertical, e tendo hidrogénio como principal fonte de energia utilizando para tal uma célula de combustível. A dissertação foca-se nas fases de desenvolvimento preliminar e detalhada no que diz respeito a estudos aerodinâmicos e desempenho em voo. A fase preliminar abrange a conceção da asa e da cauda, recorrendo ao software XFLR5, em conjunto com uma estimativa da resistência aerodinâmica total da aeronave, recorrendo a expressões semi-empíricas. Para a análise detalhada, foi utilizado o software de mecânica de fluidos computacional Fluent. A escolha do modelo de turbulência SST, em conjunto com o modelo de transição y_Re0 , é validada pelas simulação 2D do perfil SG6042, apresentando resultados consistentes com os dados experimentais. A polar aerodinâmica da asa é obtida através da simulações 3D da mesma para vários ângulos de ataque. Por forma a melhorar as propriedades aerodinâmicas da asa, foi aplicada torção à ponta da asa, movendo a região inicial da perda da ponta da asa para a raiz. O impacto do sistema de propulsão vertical na resistência aerodinâmica em voo cruzeiro é avaliado através da realização de testes em túnel de vento e simulações em Fluent. Simulações de toda a aeronave concluem que, dependendo do alinhamento dos rotores, a resistência aerodinâmica da aeronave varia entre 16.32 e 19.22 N para voo cruzeiro, resultando num tempo total de voo entre 3H05 e 3H25.This thesis is part of a project to design an unmanned aerial vehicle capable of performing vertical take-off and landing, and having hydrogen as its main energy source by using a fuel cell. The present dissertation is focused on the preliminary and detailed design phases regarding aerodynamics and flight performance studies. The preliminary phase encompasses the wing and tail design, with the aid of XFLR5, together with an estimate of the total aircraft drag by resorting to semi-empirical expressions. A longitudinal static stability analysis is conducted, and the unmanned aerial vehicle characteristics are presented after the preliminary phase of the project. For the detailed analysis, Fluent was chosen as the computational fluid dynamics software to be used. 2D simulation over the SG6042 wing airfoil validated the choice of the SST turbulence model, coupled with the y_ Re0 transition model, as the results were consistent with experimental data. The drag polar of the wing is obtained by simulating the 3D wing at various angles of attack. To enhance the wing aerodynamic properties, twist was given to the wingtip, moving the stall region from the wingtip to the root. The impact of the vertical propulsion system on the drag at cruise is assessed by performing wind tunnel tests and simulations on Fluent. Simulations of the entire aircraft conclude that, depending on the stopping position of the rotors, the drag of the aircraft varies between 16.32 and 19.22 N for cruise, which results in a total flight time between 3H05 and 3H25.N/

Autonomous Unmanned Aerial Vehicle Navigation using Reinforcement Learning: A Systematic Review

There is an increasing demand for using Unmanned Aerial Vehicle (UAV), known as drones, in different applications such as packages delivery, traffic monitoring, search and rescue operations, and military combat engagements. In all of these applications, the UAV is used to navigate the environment autonomously --- without human interaction, perform specific tasks and avoid obstacles. Autonomous UAV navigation is commonly accomplished using Reinforcement Learning (RL), where agents act as experts in a domain to navigate the environment while avoiding obstacles. Understanding the navigation environment and algorithmic limitations plays an essential role in choosing the appropriate RL algorithm to solve the navigation problem effectively. Consequently, this study first identifies the main UAV navigation tasks and discusses navigation frameworks and simulation software. Next, RL algorithms are classified and discussed based on the environment, algorithm characteristics, abilities, and applications in different UAV navigation problems, which will help the practitioners and researchers select the appropriate RL algorithms for their UAV navigation use cases. Moreover, identified gaps and opportunities will drive UAV navigation research

Development and applications of a vision-based unmanned helicopter

Ph.DDOCTOR OF PHILOSOPH

12th EASN International Conference on "Innovation in Aviation & Space for opening New Horizons"

Epoxy resins show a combination of thermal stability, good mechanical performance, and durability, which make these materials suitable for many applications in the Aerospace industry. Different types of curing agents can be utilized for curing epoxy systems. The use of aliphatic amines as curing agent is preferable over the toxic aromatic ones, though their incorporation increases the flammability of the resin. Recently, we have developed different hybrid strategies, where the sol-gel technique has been exploited in combination with two DOPO-based flame retardants and other synergists or the use of humic acid and ammonium polyphosphate to achieve non-dripping V-0 classification in UL 94 vertical flame spread tests, with low phosphorous loadings (e.g., 1-2 wt%). These strategies improved the flame retardancy of the epoxy matrix, without any detrimental impact on the mechanical and thermal properties of the composites. Finally, the formation of a hybrid silica-epoxy network accounted for the establishment of tailored interphases, due to a better dispersion of more polar additives in the hydrophobic resin

Aerial Vehicles

This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space

VERTICAL REPLENISHMENT BY UNMANNED AERIAL VEHICLES.

Master'sMASTER OF ENGINEERIN

Aeronautical engineering: A continuing bibliography with indexes (supplement 245)

This bibliography lists 537 reports, articles, and other documents introduced into the NASA scientific and technical information system in October, 1989. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics