Abstract in English:Abstract: Titanium parts are ideally suited for advanced aerospace systems because of their unique combination of high specific strength at both room temperature and moderately elevated temperature, in addition to excellent general corrosion resistance. The objective of this work is to present a review of titanium metallurgy focused on aerospace applications, including developments in the Brazilian production of titanium aimed at aerospace applications. The article includes an account of the evolution of titanium research in the Brazilian Institute (IAE/CTA) and the current state-of-art of titanium production in Brazil.
Abstract in English:Abstract: The Pilot Transonic Wind Tunnel of Institute of Aeronautics and Space (PTT Pilot Transonic Wind Tunnel) is an important result of a tremendous effort to install a high speed wind tunnel complex (TTS acronyms for Transonic and Supersonic Tunnels, in Portuguese) at the IAE, to support Brazilian aerospace research. Its history is described below, startingfrom the moment the TTS project was first conceived, highlighting each successive phase, mentioning the main difficulties encountered, and the solutions chosen, up until the final installation of the Pilotfacility. A brief description of the tunnel's shakedown and calibration phases is also given, together with the present campaigns and proposed activities for the near future.
Abstract in Portuguese:Resumo: Este trabalho descreve as ações e os resultados alcançados na otimização do processo de obtenção do pré-polímero MetilAzoteto de Glicidila (GAP). Foram obtidas amostras de poliepicloridrina (PECH) utilizando três diferentes catalisadores, BF3, SnCl4.5H20 e SnCl4 anidro, sob diferentes condições e cada amostrafoi convertida, posteriormente, no pré-polímero GAP. Cada uma das amostras foi submetida às análises por FT-IR, determinação do índice de hidroxila e determinação da massa molar. Ao final, os resultados obtidos foram comparados com os valores previamente estabelecidos e determinado o melhor método de obtenção do GAP.
Abstract in English:Abstract: This paper describes the action and results achieved during the optimization of Glycidyl Azide Polymer (GAP) characterization and process. Under different conditions, three different kinds of catalysts, BF3, SnCl4.5H20 and SnCl4 were used to obtain polyepichlorohydrin and each sample was converted into GAP. Ali the samples were submittedfor characterization analysis by FT-IR and determination of molecular mass and hydroxyl value. Finally, results were compared and the best method to obtain GAP was determined.
Abstract in English:Abstract: Synthesis and characterization of energetic ABA-type thermoplastic elastomers for propellant formulations has been carried out. Following the working plan elaborated, the synthesis and characterization of Poly 3-bromomethyl-3-methyl oxetane (PolyBrMMO), Poly 3- azidomethyl-3-methyl oxetane (PolyAMMO), Poly 3,3-bis-azidomethyl oxetane (PolyBAMO) and Copolymer PolyBAMO/AMMO (by TDI end capping) has been successfully performed. The thermoplastic elastomers (TPEs) were synthesized using the chain elongation process PolyAMMO, GAP and PolyBAMO by diisocyanates. In this method 2.4-toluene diisocyanate (TDI) is used to link block A (hardandmono-functional)) to B (soft and di-functional). For the hard A-block we used PolyBAMO and for the soft B-block we used PolyAMMO or GAP. This is ajoint project set up, someyears ago, between the Chemistry Division of the Institute of Aeronautics and Space (IAE) - subordinated to the Brazilian Ministry of Defense - and the Fraunhofer Institut Chemische Technologie (ICT), in Germany. The products were characterized by different techniques as IR- and (1H, 13C) NMR spectroscopies, elemental and thermal analyses. New methodologies based on FT-IR analysis have been developed as an alternative for the determination of the molecular weight and CHNO content of the energetic polymers.
Abstract in English:Abstract: Nano-scale aluminum particles are innovative materiais increasingly used in energetic formulations. In this contribution, the rheological behavior of suspensions with either paraffin oil or HTPB as the matrix fluid and nano-scale aluminum (ALEX) as the dispersed phase is described and discussed. The paraffin oil/aluminum suspensions exhibit non-Newtonian flow behavior over a wide range of concentrations, where as the HTPB/aluminum suspensions exhibit Newtonian behavior (i.e. the viscosity is independent of shear stress) up to a concentration of 50 vol.% aluminum. Both systems have unusual viscoelastic properties in that their elastic moduli are independent of the solids concentration.
Abstract in Portuguese:Resumo: O principal objetivo do presente trabalho foi a determinação do módulo de cisalhamento G12 e a máxima resistência ao cisalhamento (ô12) utilizando o ensaio de cisalhamento losipescu. Os testes foram conduzidos com dois tipos de compósitos, fibra de carbono/epóxi e fibra de vidro/epóxi utilizados na indústria aeroespacial e também uma matriz de resina moldada. Os resultados indicam a efetiva contribuição das fibras de reforço para a resistência ao cisalhamento (ô12) e para o módulo de cisalhamento (G12) comparado com a matriz polimérica sem reforço.
Abstract in English:Abstract: The main aim of the present work was the determination of the shear modulus (GI2) and the maximum shear strength (ôI2) using the losipescu Shear Test. Tests were carried out on two types of composites, carbon fiber/epoxy and glass fiber/epoxy, used in the aerospace industry, and also a molded epoxy resin matrix. The results indicate the effective contribution of fiber reinforcements to the shear strength (ô12) and shear modulus (G12) compared to the no reinforcement polymer matrix.
Abstract in Portuguese:Resumo: Um novo método de análise por via úmida e instrumental foi desenvolvido para avaliação da abertura do anel aziridínico do óxido de tris(l-(2-metil)aziridinil) fosfina (MAPO), agente de ligação usado em propelente compósito. Foi observada redução de intensidade das bandas de absorção em 1400 e 1040 cm-1, que são características do anel aziridínico. Em alguns casos, observou-se que, quando o número de anéis abertos aumenta, a banda de absorção do grupo NH, na região 3400 e 3300 cm-1, que aparece com a abertura do anel, está localizada na região de menor número de onda. O estudo de síntese do derivado do MAPO evidenciou reações secundárias com a hidroxila do ácido 12-hidroxiesteárico, homopolimerização e reação com a umidade existente na amostra.
Abstract in English:Abstract: A new method using wet chemistry and instrumental analysis has been developed for evaluating the ring-opening of aziridine tris [l-(2 methyl) aziridinyl] phosphide oxide (MAPO) of the bonding agent used in composite propellant. A reduction was observed in the intensity absorption bands in 1400 and 1040 cm-1, characteristic of aziridinic ring. It was also observed, in some cases, that when the number of open aziridinyl ring increases, the NH band in the range 3400-3300 cm-1, that appears with ring-opening, is located in the region of lower wave numbers. The study of the synthesis of MAPO derivative indicated side reactions such as homopolymerization of rings and also, with secondary hydroxyl of the 12-hydroxy stearic acid and probable humidity existent in the original sample.
Abstract in English:Abstract. Quartz phenolic composites have been applied to thermal protection systems (TPSs) for reentry vehicles since the late fifties due to their excellent ablative resistance and mechanical performance. TPSs must withstand the aggressive reentry environment, such as atomic oxygen, when submitted to very high temperatures (> 1000° C) and heat flux. The ablative performance of composites is influenced by both base materiais and environmental parameters during the ablation process. For TPS systems phenolic resin is usually used as the base matrix due to its ability to form a stable char during decomposition. This charplays an important role in the absorption of the heat generated during the ablation process. During re-entry, parts of the charred matrix can be abrasively removed by shear force due to high pressure and velocity. In this work the ablative and mechanical properties of quartz phenolic composites were evaluated in order to identify the range of properties suitable for the use of these materiais as thermal protection systems for space vehicles. Quartz fabric having an areai weight of 680 g/m2 and a resole-typephenolic resin were used to prepare the composites. The resin has a viscosity of l65 MPa at 20°C. The prepreg material was cured by heating under pressure of 100 bar in a mold. The resin content of the prepreg obtained was about 50 per cent. The mechanical properties evaluated were, tensile, shear and flexural strength. The results obtained showed that this material has average values of 38.5 MPa, 52 MPa and 85 MPa for tensile, shear andflexural strength, respectively. The ablative tests were carried out in a high-energy air plasma in ambient atmosphere and the mass losses were measured for different exposure time.
Abstract in English:Abstract: A conceptual control model for the Reynolds number test based on isentropic relations was established for the supersonic wind tunnel. Comparison of the system response of the model simulation and the actual wind tunnel test data was made to design the control system. Two controllers were defined: the first one was based on the stagnation pressure at the settling chamber; the second was based on the relation between stagnation pressure and temperature at the settling chamber which represents the Reynolds number specified for the test. A SIMULINK® block diagram code was used to solve the mathematical model consisting of mass and energy conservation equations. Performance of the supersonic wind tunnel using a PI (proportional-plus-integral) controller was found to be satisfactory, as confirmed by the results.
Abstract in Portuguese:Resumo: No lançamento dos primeiros protótipos do Veículo Lançador de Satélites (VLS-1), diferentes falhas impediram o cumprimento da missão. Em 2005, foi decidido realizar novos ensaios em vôo, denominados tecnológicos, com propósito de testar os sistemas do veículo. O objetivo do trabalho é avaliar a decisão sobre a necessidade de realização do segundo vôo tecnológico, XVT02, para a continuidade e sucesso do projeto VLS-1, com base na utilização de um método multicritério de apoio à decisão. Foi aplicado um processo decisório em grupo, com especialistas de diversas áreas do projeto. A agregação de julgamentos permitiu sintetizar a decisão do grupo, cujo resultado comprovou a decisão que já havia sido tomada, ou seja, realizar os ensaios em vôo tecnológicos.
Abstract in English:Abstract: With the launch of the first prototypes of the Satellite Launch Vehicle VLS-1, different failures prevented accomplishing the mission. Then, in 2005, it was decided to carry out test flights with the purpose of testing all the systems in the vehicle. The proposal of the work is to assess the decision of conducting the second test flight XVT02 for the continuity and success of project VLS-1 basedon a decision support multicriteria method. A group decision process was applied, with specialists from diferent areas of the project. The aggregating judgments approach led to integrate the group decision and the ensuing findings confirmed the decision taken previously, of carrying out the tests flight.
Abstract in English:Abstract: The Alcântara Space Center (ASC) region has a peculiar topography due to the existence of a Coastal cliff, which modifies the atmospheric boundary layer characteristic in a way that can affect rocket launching operations. Wind tunnel measurements can be an important tool for the understanding of turbulence and wind flow pattern characteristics in the ASC neighborhood, along with computational fluid dynamics and observational data. The purpose of this paper is to describe wind tunnel experiments that have been carried out by researchers from the Brazilian Institutions IAE, ITA and INPE. The technologies of Hot-Wire Anemometer and Particle Image Velocimetry (PIV) have been used in these measurements, in order to obtain information about wind flow patterns as velocity fields and vorticity. The wind tunnel measurements are described and the results obtained arepresented.
Abstract in Portuguese:Resumo: Este trabalho apresenta as atividades na área de propulsão líquida no IAE, que teve um impulso efetivo no final da década de 90. É consenso entre os especialistas da área espacial a utilização da tecnologia de propulsão líquida nas futuras gerações de veículos lançadores de satélites, com o objetivo de elevar significativamente o desempenho do foguete e a precisão de inserção de satélites. Diversas atividades nesta área encontram-se em desenvolvimento, entre as quais podem ser citadas: os motores L5, L15 e L75, as especificações das instalações de testes de motores, componentes e estágios de foguetes, além de um programa de capacitação de recursos humanos nas áreas de projeto, fabricação e testes de motores foguetes desta natureza.
Abstract in English:Abstract: This paper presents the activities in the area of liquid propulsion, which received an effective boost at the end of the 90s. There is a consensus among specialists on the use of liquid propulsion in the next generation of satellite launcher vehicles in order to increase significantly both the performance and the satellites insertion accuracy. Several activities in this area are in development, among which should mention, the L5, the L15 and the L75 LPRE, the specifications for engine testing facilities for components and rocket stages, and a human resources program for training in the areas of liquid rocket engine design, manufacture and testing.
Abstract in English:Abstract: This paper presents an overview of the activities developed by the Structural Integrity Group at the Institute of Aeronautics and Space - IAE, Brazil, as well as the status of ongoing work related to the life extension program for aircraft operated by the Brazilian Air Force BAF. The first BAF-operated airplane to undergo a DTA-based life extension was the F-5 fighter, in the mid 1990s. From 1998 to 2001, BAFworked on a life extension project for the BAFAT-26 Xavante trainer. All analysis and tests were performed at IAE. The fatigue critical locations (FCLs) were presumed based upon structural design and maintenance data and also from exchange of technical information with other users of the airplane around the world. Following that work, BAF started in 2002 the extension of the operational life of the BAF T-25 "Universal". The T-25 is the basic training airplane used by AFA - The Brazilian Air Force Academy. This airplane was also designed under the "safe-life" concept. As the T-25 fleet approached its Service life limit, the Brazilian Air Force was questioning whether it could be kept inflight safely. The answer came through an extensive Damage Tolerance Analysis (DTA) program, briefly described in this paper. The current work on aircraft structural integrity is being performed for the BAF F-5 E/F that underwent an avionics and weapons system upgrade. Along with the increase in weight, new configurations and mission profiles were established. Again, a DTA program was proposed to be carried out in order to establish the reliability of the upgraded F5 fleet. As a result of all the work described, the BAF has not reported any accident due to structural failure on aircraft submitted to Damage Tolerance Analysis.
Abstract in English:Abstract: The Brazilian F-5 was submitted to avionics and weapons upgrade. This "new" aircraft has proven to be heavier and more capable. A comprehensive damage tolerance analysis is being performed to evaluate how the new mission profiles and weight distribution may affect the airframe structural integrity. Operational data were collected at the Brazilian Air Force Bases where the fighter is flown. Software was developed in order to acquire, filter and anafyze flight data. This data was used for comparison between the pre and post modernization mission profiles and to determine the stress level in each of the known aircraft fatigue critical locations (FCL). The results show that the change in aircraft weight and balance and the new operational profile can significantly change the inspection intervals of certain fatigue critical locations of the structure. A preliminary result for the horizontal tail has shown that this component will have a much more restrictive maintenance schedule to assure flight safety.