Authors:André Luis da Silva, Marcelo Serrano Zanetti Abstract: The Brazilian Aerospace Congress (CAB) is an event that aims at the synergy of institutions related to the Brazilian aeronautical and astronautics sector. The second edition of the event took place between September 16th and 19th, 2019, in Santa Maria, Rio Grande do Sul, with the theme: “Debates and Dialogue between the Actors of the Brazilian Aerospace Sector” PubDate: 2020-11-22 Issue No:Vol. 12 (2020)
Authors:Artem Andrianov, Jungpyo Lee, Gabriela Possa, Hiterson de Oliveira Silva Abstract: The objective of this study was to characterize the thermal insulation efficiency of the silicone rubber reinforced composites by oxyacetylene torch. These composites reinforced by glass, carbon, ceramics and silica fibers were intended to be used as ablators in a low-thrust hybrid propulsion motor. The back-face temperature measurements were used as a criterion for insulation efficiency of the specimens, whose frontal face is subjected to the oxyacetylene flame for 40 s. The paper includes the results of the ablation rate measurements and the influence of orientation of glass and carbon fibers relatively to the flame direction on the back-face temperature of the specimens. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Authors:Graziela Fernanda de Souza Maia, Marcelo Lopes de Oliveira e Souza, Alírio Cavalcanti de Brito Abstract: One of the processes that determine the reliability of solar panels used in space applications is the welding of interconnections between two adjacent solar cells. This process has various technologies, sequences and activities that have various characteristics, factors and parameters. Their combinations and values allow countless possibilities, making their adjustments time consuming, costly and exhausting. One way of abbreviating this, achieving competitiveness and meeting the needs of stakeholders is through the Analysis and Design of Experiments. This technique helps in optimizing the best adjustments to obtain the expected results. Thus, this paper presents a preliminary analysis of the parameters and their interactions of the welding process (by parallel-gap resistance welding) of interconnections between solar cells using design of experiments. In this welding process, the cell undergoes a certain level of degradation. For this reason, it is important to determine which process parameters are important and their proper levels, without big cell degradation. The result of this analysis can be used in the future to optimize the welding process meeting the design requirements for reliability and performance. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Authors:Leonardo César Freitas, Olexiy Shynkarenko Abstract: The work is focused on the performance estimation and control of a cold flow inside a ramjet test engine, which initially operates without combustion, preparing the flow for the main propulsive phase. To achieve this objective, a “connected pipe” test bench was assembled. Flow management was performed using the control valve that allows regulating pressure and air mass flow rate in the engine according to its flight conditions through sensors installed at relevant positions. The proportional, integral and derivative (PID) parameters for the flow control algorithm were studied in order to guarantee the stable operation of the engine and correspondence of the flow parameters to predicted ones by the analytical modeling. Experimental results were validated by the numerical and analytical compressible flow models. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Authors:Artur Gustavo Slongo, Deniel Desconzi Moraes, Lorenzzo Quevedo Mantovani, Mateus Schmitz Venturini Abstract: The use of unmanned aircraft vehicles (UAVs) for the most diverse aeronautic missions is a reality. Then, with the rise of precision agriculture (PA), the viability of the incorporation of this technology in the countryside on both big and small proprieties is under study. This work aims to analyze the handling qualities of an UAV with a mission of pest control chemical spraying. With this objective, aircraft data was used to analyze the eigenvalues of the aircraft modes. Then, the impact of mass and inertia variation during its mission was studied. Also, the longitudinal and latero-directional dynamics were evaluated based on the Cooper–Harper scale. The results found indicate that all aircraft modes are stable for both full hopper and empty hopper conditions. Moreover, the determined handling quality grades of the UAV in the Cooper–Harper scale indicate the need for some correction applied by the pilot during flight. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Authors:Samara Herrmann, Macklini Dalla Nora, Thompson Diordinis Metzka Lanzanova Abstract: Reciprocating internal combustion engines have wide application in agricultural, recreational and experimental aircraft, resulting from their low cost and less complex maintenance compared to other engines. Thus, this work analyzed the performance of a conventional four-stroke engine operating in the two-stroke cycle by means of direct fuel injection and mechanical air supercharging. The use of a supercharger was essential in this design to provide adequate gas exchange inside the cylinder during the long valve overlap required, while direct fuel injection made it possible to reduce the short circuit of air-fuel mixture to the exhaust. Due to the double ignition frequency compared to a four-stroke engine, it was possible to obtain a large power density (40 kW/L) at a speed of 2400 rpm, also a specific fuel consumption of 270 g/kWh with gasoline and 400 g/kWh with ethanol. The use of ethanol in replacement of gasoline made it possible to operate at full load (160 Nm/L) at 800 rpm without the occurrence of knocking combustion. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Authors:Artur Gustavo Slongo, André Luís da Silva, Deniel Desconzi Moraes, João Felipe de Araújo Martos, Lorenzzo Quevedo Mantovani, Mateus Schmitz Venturini, Róger Mateus Sehnem Abstract: During the last decade, the world faced the mass insertion of small satellites in the space technology scenario. Every year, the number of micro and nanosatellites launched increases and gets more attention from players in the space market. Despite the lack of a national launcher, the Brazilian Space Program is known for some successful development in the last century, including its space assets, such as a privileged launch site near the equator, a family of flight proven and reliable sounding rockets for suborbital flights and microgravity experiments and universities with established small satellites programs. Thereby, the present work proposes a modification of the Brazilian VSB-30 sounding rocket in order to allow the launch and insertion in low Earth orbit (LEO) of small satellites fulfilling the gap of a national launcher. It also presents a CubeSat orbital decay simulation and orbital insertion simulation with the modified rocket launched from the Alcântara Launch Center as a matter of verifying the potential of national missions using this modified launcher. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Authors:Antonio Cassiano Julio Filho, Auro Tikami, Elaine de Souza Ferreira de Paula, Jhonathan Murcia Piñeros, George Favale Fernandes, Lázaro Aparecido Pires Camargo, Carlos Alberto Monteiro Barbosa dos Santos, Walter Abrahão dos Santos, Kleber Pinheiro Naccarato Abstract: Annually, severe weather phenomena are responsible for tens of thousands of deaths and tens of billions of dollars of damage around the world. In Brazil, unlike other hydrometeorological events, severe atmospheric events are random and, therefore, do not have a sociospatial pattern. Because of that, there is a significant motivation to improve the prediction techniques for this kind of events, using high resolution numerical models. A large amount of high-quality observational data is required, including lightning data in a very short-range. In addition, the detection of lightning flashes produced by storms is important for a wide variety of applications and in some areas of scientific research, which include the understanding of the human action on the climate and how the climate change can affect the behavior of storms in long range. One method to monitor the lightning flashes is the implementation of sensors in satellites to obtain data. In this sense, the objective of the RaioSat project is to develop national technology for detecting lightning flashes from the space, in order to complement the existing data from the ground detection network, BrasilDAT. The main objective of this article is to present a methodology for the development of the RaioSat mission including some parts of the preliminary design and operational modes. Additionally, the article describes the expected results and the continuity of the project and a preliminary analysis of a constellation for future projects. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Authors:Kenedy Matiasso Portella, Wilcker Neuwald Schinestzki, Róger Mateus Sehnem, Leonardo Barros da Luz, Lorenzzo Quevedo Mantovani, Renan Rathis Sacco, Tarso Kraemer Sarzi Sartori, Pedro Paglione Abstract: In space missions, there is often a need for an attitude control system capable of maintaining the desired attitude. In situations that require agile and accurate responses, which also require large torques, control moment gyroscopes (CMGs) may be used. Control moment gyroscopes are high angular moment gyros mounted on gimbals and are responsible for changing the direction of the angular momentum vector, consequently generating the control torques. There are several linear and nonlinear techniques that can be employed in the design of control laws with the final choice being a compromise between simplicity, effectiveness, efficiency and robustness. The main objective of this study is to evaluate the performance of control systems techniques with 4 CMGs in a pyramidal arrangement, either by using Linear Quadratic Tracker (LQT) with integral compensator or Exponential Mapping Control (EMC). A reference attitude will be defined to be traced in the presence of disturbance torques caused by the gravitational gradient. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Authors:Maria Cecilia Zanardi, Paola da Rosa Prado, Leandro Baroni Abstract: This paper proposed a study of a spatial tether system (STS), composed by two satellite (a main satellite and a subsatellite), with the objective of developing a control system in which the motion of the subsatellite is limited in the orbital plane of the main satellite. The linear quadratic regulator (LQR) method is used to implement this control, which is an optimal control with state feedback to predict the linearization of the equations of motion to calculate the feedback gain, using the resolution of Riccati equation. The results show an effective control, with the motion of the subsatellite limited only to the stretch of the cable that links both satellites. However, it is necessary to introduce an auxiliary torque, since the linearized equation associated with the second variation of the angle out of the plan does not have a term independent of the state vector. PubDate: 2020-11-21 Issue No:Vol. 12 (2020)
Open Access journal
