Resumo em Inglês:

Abstract: The Satellite Launch Vehicle electrical network, which is currently being developed in Brazil, is sub-divided for analysis in the following parts: Service Electrical Network, Controlling Electrical Network, Safety Electrical Network and Telemetry Electrical Network. During the pre-launching and launching phases, these electrical networks are associated electrically and mechanically to the structure of the vehicle. In order to succeed in the integration of these electrical networks it is necessary to employ techniques of electrical power distribution, which are proper to Launch Vehicle systems. This work presents the most important techniques to be considered in the characterization of the electrical power supply applied to Launch Vehicle systems. Such techniques are primarily designed to allow the electrical networks, when submitted to the single-phase fault to ground, to be able of keeping the power supply to the loads.

Resumo em Inglês:

Abstract: Over the last 40 years, many solid and liquid rocket motors have experienced combustion instabilities. Among other causes, there is the interaction of acoustic modes with the combustion and/or fluid dynamic processes inside the combustion chamber. Studies have been showing that, even if less than 1% of the available energy is diverted to an acoustic mode, combustion instability can be generated. On one hand, this instability can lead to ballistic pressure changes, couple with other propulsion systems such as guidance or thrust vector control, and in the worst case, cause motor structural failure. In this case, measures, applying acoustic techniques, must be taken to correct/minimize these influences on the combustion. The combustion chamber acoustic behavior in operating conditions can be estimated by considering its behavior in room conditions. In this way, acoustic tests can be easily performed, thus identifying the cavity modes. This paper describes the procedures to characterize the acoustic behavior in the inner cavity of four different configurations of a combustion chamber. Simple analytical models are used to calculate the acoustic resonance frequencies and these results are compared with acoustic natural frequencies measured at room conditions. Some comments about the measurement procedures are done, as well as the next steps for the continuity of this research. The analytical and experimental procedures results showed good agreement. However, limitations on high frequency band as well as in the identification of specific kinds of modes indicate that numerical methods able to model the real cavity geometry and an acoustic experimental modal analysis may be necessary for a more complete analysis. Future works shall also consider the presence of passive acoustic devices such as baffles and resonators capable of introducing damping and avoiding or limiting acoustic instabilities.

Resumo em Inglês:

Abstract: The classical metrics of ground segment site location do not take account of the pattern of ground segment access to the satellite. In this paper, based on the pattern of access between the ground segment and the satellite, two metrics for site location of ground segments in Low Earth Orbits (LEO) missions were developed. The two developed access-based metrics are total accessibility duration and longest accessibility gap in a given period of time. It is shown that repeatability cycle is the minimum necessary time interval to study the steady behavior of the two proposed metrics. System and subsystem characteristics of the satellite represented by each of the metrics are discussed. Incorporation of the two proposed metrics, along with the classical ones, in the ground segment site location process results in financial saving in satellite development phase and reduces the minimum required level of in-orbit autonomy of the satellite. To show the effectiveness of the proposed metrics, simulation results are included for illustration.

Resumo em Inglês:

Abstract: Computer systems are increasingly used in space, whether in launch vehicles, satellites, ground support and payload systems. Software applications used in these systems have become more complex, mainly due to the high number of features to be met, thus contributing to a greater probability of hazards related to software faults. Therefore, it is fundamental that the specification activity of requirements have a decisive role in the effort of obtaining systems with high quality and safety standards. In critical systems like the embedded software of the Brazilian Satellite Launcher, ambiguity, non-completeness, and lack of good requirements can cause serious accidents with economic, material and human losses. One way to assure quality with safety, reliability and other dependability attributes may be the use of safety analysis techniques during the initial phases of the project in order to identify the most adequate dependability requirements to minimize possible fault or failure occurrences during the subsequent phases. This paper presents a structured software dependability requirements analysis process that uses system software requirement specifications and traditional safety analysis techniques. The main goal of the process is to help to identify a set of essential software dependability requirements which can be added to the software requirement previously specified for the system. The final results are more complete, consistent, and reliable specifications.

Resumo em Inglês:

Abstract: The purpose of this work was to assess the development of solid state joints of dissimilar material AA1050 aluminum and AISI 304 stainless steel, which can be used in pipes of tanks of liquid propellants and other components of the Satellite Launch Vehicle. The joints were obtained by rotary friction welding process (RFW), which combines the heat generated from friction between two surfaces and plastic deformation. Tests were conducted with different welding process parameters. The results were analyzed by means of tensile tests, Vickers microhardness, metallographic tests and SEM-EDX. The strength of the joints varied with increasing friction time and the use of different pressure values. Joints were obtained with superior mechanical properties of the AA1050 aluminum, with fracture occurring in the aluminum away from the bonding interface. The analysis by EDX at the interface of the junction showed that interdiffusion occurs between the main chemical components of the materials involved. The RFW proves to be a great method for obtaining joints between dissimilar materials, which is not possible by fusion welding processes.

Resumo em Inglês:

Abstract: The main objective of these studies was the synthesis and characterization of new energetic binders and their use in some propellant formulations. Following the working plan elaborated, the synthesis and characterization of the following compounds has been done successfully: GAP; energetic Monomer BAMO; energetic Binders; copolymer GAP/PolyBAMO. The scale up for the synthesis of copolymer GAP/PolyBAMO and PolyBAMO using GAP as initiator has been done and they were fully characterized by IR, (1H, 13C) NMR-spectroscopy, GPC, elemental analysis, OH-functionality, differential scanning calorimetry (DSC) and sensitivity tests (friction, impact). For this two scale up synthesis some propellant formulations were carried out and the results of mechanical and burning properties have been compared with GAP propellants.

Resumo em Inglês:

Abstract: Copper chromites are well known as burning rate catalysts for the combustion of composite solid propellants, used as a source of energy for rocket propulsion. The propellant burning rate depends upon the catalyst characteristics such as chemical composition and specific surface area. In this work, copper chromite samples from different suppliers were characterized by chemical analysis, FT-IR spectroscopy and by surface area measurement (BET). The samples were then evaluated as burning rate catalyst in a typical composite propellant formulation based on HTPB binder, ammonium perchlorate and aluminum. The obtained surface area values are very close to those informed by the catalyst suppliers. The propellant processing as well as its mechanical properties were not substantially affected by the type of catalyst. Some copper chromite catalysts caused an increase in the propellant burning rate in comparison to the iron oxide catalyst. The results show that in addition to the surface area, other parameters like chemical composition, crystalline structure and the presence of impurities might be affecting the catalyst performance. All evaluated copper chromite samples may be used as burning rate catalyst in composite solid propellant formulations, with slight advantages for the SX14, Cu-0202P and Cu-1800P samples, which led to the highest burning rate propellants.

Resumo em Português:

Resumo: Embora a composição química seja a mesma, as propriedades físico-químicas dos polimorfos podem ser totalmente distintas, como, por exemplo, a condução ou não de eletricidade. Discute-se até mesmo a legalidade de reconhecê-los como produtos totalmente novos, dadas as características próprias que um polimorfo pode ter em detrimento de outro. Fato é que os diferenciais de solubilidade, estabilidade e formação de sítios ativos de fases distintas de uma substância despertam interesse dos variados setores economicamente ativos. Não são poucos os materiais energéticos polimórficos, ou precursores deles, que também apresentam aplicações terapêuticas. Portanto, algumas das técnicas desenvolvidas pela lucrativa indústria farmacêutica para o estudo do polimorfismo podem ser adaptadas às necessidades da indústria de material de defesa. Este trabalho visou apresentar materiais energéticos e farmacológicos reconhecidos por seu polimorfismo, bem como discorrer sobre propriedades, técnicas de caracterização e estudo de transição de fase nesses materiais.

Resumo em Inglês:

Abstract: Despite the same chemical composition, the physicochemical properties of polymorphs can be totally different, such as leading or not electricity. The legality of recognize them as completely new products is discussed, in front of the characteristics that a polymorph may have over another. The fact is that the differential solubility and stability and formation of active sites in different phases of a substance engage the interest of many active sectors of the economy. There are no few polymorphic energetic materials, or their precursors, which also have therapeutic applications. Therefore, some of the techniques developed by the lucrative pharmaceutical industry to study the polymorphism can be tailored to the needs of the war industry. This paper presents energetic and pharmacological materials recognized for their polymorphism and discuss properties, characterization techniques and the study of phase transition in these materials.

Resumo em Inglês:

Abstract: The prioritization of R&D projects in the Aerospace Sector is considered a complex problem because it involves qualitative and quantitative issues that are frequently conflicting. This paper aimed to apply the AHP (Analytic Hierarchy Process) method with ratings to select projects of R&D in a Brazilian aerospace institution, Department of Science and Aerospace Technology (DCTA). The results showed that using ratings is appropriate when there is a great quantity of projects, since it reduces the judgments required to the decision maker.

Resumo em Inglês:

Abstract: We present in this paper a case of technological competence development in the aerospace sector in Brazil, by addressing the complete cycle of integrated circuits for satellite applications, an area of high technology which is strategic to the country. The development of technological and business competences is linked to an understanding of the existing relations between different participating institutions, both public and private. There is an effort to establish a network for the development of radiation-hard integrated circuits in Brazil, comprising universities, research centers, private companies, design houses, funding and governmental agencies. These institutions have been working to define their roles, through participation in federally funded projects to develop robust component technology for the aerospace industry in Brazil. As a means to maintain and improve this network, it is suggested that long term planning tools such as technology roadmaps be adopted, as well as measures to increase awareness of and help clarify intellectual property issues, which is considered a significant bottleneck to advance technology development in this area. In this sense, open innovation may be considered an alternative for competitively enhancing the outcomes of the sector.

Resumo em Inglês:

Abstract: Communication skills have been considered a strategic asset for any kind of organization. However, technical-oriented enterprises usually emphasize the virtues of a cluster of technical competences and technological resources availability. So, this paper aimed to discuss communication skills development beyond technical communication in a high technology and technical-based operation, such as ground and flight operations. To do so, this article describes some tragic-ending cases in commercial aviation in which the poor quality of interpersonal communication was identified as the one of the most influential causes of the aircraft, or at least that was seen as a compelling force for creating the perfect backdrop for a disaster involving civilian aircrafts. Methodological procedures were basically addressed to a qualitative approach, supported by a documental research considering some of the most documented cases of aircraft accidents reported by the Aviation System Safety Report, issued by Federal Aviation Administration (FAA), USA, as well as reports of accidents provided by The National Transportation Safety Board (NTSB), USA, and by the Center for Aircraft Research and Prevention (Cenipa), Brasil.

Resumo em Português:

Resumo: Este artigo trata do Sistema de Identificação Amigo-Inimigo (IFF) com tecnologia genuinamente nacional, incluindo o Modo 4 com criptografia autóctone. São apresentados fratricídios reais e os métodos do país para reduzi-los. Aspectos técnicos dos sistemas IFF em uso pela Organização do Tratado do Atlântico Norte (OTAN), são revistos e atualizados com base nas Normas de Padronização da OTAN 4193. A análise mostra que o estágio atual de desenvolvimento da Indústria Nacional de Defesa, combinado à sua capacidade de integração com os centros tecnológicos das Forças Armadas, bem como as disponibilidades orçamentárias para a pesquisa e o desenvolvimento, fruto da Política de Defesa Nacional, são fatores para o êxito do projeto. Também expõe a importância da combinação da defesa aérea e controle do tráfego aéreo no Brasil como fator de sucesso do trabalho. A solução deve ser baseada na manutenção dos padrões da OTAN das características técnicas dos interrogadores e transponders do IFF Mark XII, mantidos os processos de interrogação e "resposta". Indica-se a necessidade de subsídios para estudo da incorporação do Modo 5 e Modo S, em segunda etapa.

Resumo em Inglês:

Abstract: This paper discusses the System of Identification Friend-Foe (IFF) with genuinely national technology, including Mode 4 with native encryption. Actual fratricides are illustrated and the Brazilian processes to reduce them are shown. Technical aspects of IFF systems in use by the North Atlantic Treaty Organization (NATO), are reviewed and updated based on the standards of NATO Standardization Agreement (STANAG 4193). The analysis shows that the current stage of development of the industry of National Defense, coupled with its ability to integrate with the technological centers of the Armed Forces, as well as the availability of budget for research and development, resulting from the National Defense Policy, are factors for the success of the project. Also, it exposes the importance of combining air defense and air traffic control in Brazil as a determinant factor for the success of the task. The solution should be based on maintaining the standards laid down in STANAG 4193 technical characteristics of interrogators and transponders of IFF Mark XII, keeping the processes of interrogation and "response". Results indicate the need of providing grants to study the incorporation of Mode 5 and Mode S, in a second step.