Percorrer por autor "Sousa, Joana Carlota Caires"
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- Solar System for a Long Endurance Electric UAVPublication . Sousa, Joana Carlota Caires; Gamboa, Pedro VieiraFossil fuels such as coal, oil and natural gas, are the worldwide primary energy resources. Energy is essencial to the peoples’ well-being and society development, as it is known today and expected in the future to produce and use energy in a sustainable way is vital to our civilization. However, dependence on fossil fuel is awfully high and it is necessary to hinder their use in several industries as it is a limited resource. In the Aeroespace Industry solar energy has been gaining widespread development, becoming the solution to many negative factors. This Master Thesis includes a conceptual design of an electric propulsion system for a UAV with a wingspan of 4.5 m and a weight of approximately 52 N. The construction of this system is different from conventional propulsion methods, so the design and sizing rely on the available energy stored in the battery and the power generated by the solar panels. As solar radiation is different throughout the year, a plan for experimental tests was drafted to verify the system viability. Experiments show that exact azimuth orientation is not critical, vertical axis given by pitch and roll, have a more important effect on performance. Although it is a small aircraft, the wing beyond its aerodynamics function, has a proper zone where solar cells should be placed. Appealing to a second order differentiation it is possible to determine that solar panels should be placed at 1.5 cm from the trailing edge affecting as little as possible the airfoil. A mission simulation was done to understand the propulsion system feasibility. Although, the eight hour sustainable-flight was not possible to replicate the motor still ran for 5 hours, being the battery charged during cruise phase as pretended. Therefore, proper solar cells placement, development of a mounting method and electrical circuit design are carried out in order to allow the UAV to achieve a sustainable-flight.