Resumo em Inglês:

ABSTRACT: The natural terrestrial environment plays a significant role in the design and operation of aerospace vehicles (space vehicles and rockets) and in the associated integrity of aerospace systems and elements. Addressed herein are some of the key vehicle and environment areas of concern plus "lessons learned" that have been identified over a number of years. Many of these aerospace meteorology related events occurred during the development and interpretation of natural environment inputs, especially those of terrestrial environment, used in the design and development of the Saturn Apollo and Space Shuttle vehicles plus associated mission operations. Background is given regarding the actions needed to avoid having to re-learn these lessons.

Resumo em Inglês:

ABSTRACT: The present work addresses a sensitivity analysis investigation of the aeroelastic stability margins for the VSB-30 sounding rocket during the atmospheric flight phase. Parametric stability analyses are performed considering variations of the inertia properties of the modular payload. Such variations can be caused by different type and/or number of experiments (payload modules). The aerodynamic model is based on a supersonic unsteady potential aerodynamic method. Freestream conditions depend on the flight speed and atmosphere. An equivalent structural dynamic model of the rocket is represented by a beam-like structure. The objective of this investigation is to establish an aeroelastic model for aeroelastic stability and response analyses, as well as a procedure for the identification of stability margins for rockets. The resulting aeroelastic model should be further used in MDO processes for the improvement of the vehicle flight performance. The results of the present effort indicate that the flutter behavior of the VSB-30 sounding rocket is sufficiently robust inside the operational envelope, even considering the environmental and loading conditions. The spinning effect, in this case, does not play a significant role, because the flutter margins remain almost unaltered with and without VSB-30 body spin.

Resumo em Inglês:

ABSTRACT: The wind energy research has grown substantially in the past few years, considerably fostered by the pursuit for a clean and sustainable energy source. Improvements on the design methods are increasingly needed. The purpose of this research is to investigate the use of the Loewy's lift deficiency function (LDF), also named Returning Wake Model, coupled with a non-stationary Blade Element-Momentum Method (BEM). The LDF simulates the influence of the wake behind the wind turbine on its capacity to generate power. It is expected that this model reduce the dependency of the several empirical parameters necessary in other wake models which are currently used. Aiming to validate the results obtained in this new approach they are compared with those provided by commercial computational software and they have proven to be very consistent. It is concluded that the method is feasible to be used as an efficient design and optimization tool of upwind horizontal axis wind turbine blades.

Resumo em Inglês:

ABSTRACT: Scientists at the laboratory of Força Aérea Brasileira (FAB) have demonstrated experimentally that laser-induced "air spikes" (DEAS) may reduce effectively both total vehicle drag and heating at hypervelocities. Now, we apply the Rayleigh flow to directly determine the degree of reduction in vehicle drag and convective heat flux into the airframe of a hypersonic blunt-body when laser energy is added upstream of the flight path. Our numerical findings are in accordance with the physical trends observed in our previous hypersonic laser-induced DEAS experiments.

Resumo em Inglês:

ABSTRACT: The aim of this paper was to identify, for a specific maneuver, the optimal combination between the trajectory and the associated heat shield configuration, namely the locations and thicknesses of the ablative and reusable zones, that maximize the allowable payload mass for a spacecraft. The analysis is conducted by considering the coupling between the trajectory's dynamics and the heat shield's thermal behavior while using a highly representative model of the heat shield. A global optimization procedure and original software were developed and implemented. The analyzed mission considers an aeroassisted transfer from two low Earth orbits with an assigned orbital plane change maneuver for a given delta wing vehicle equipped with a heat shield consisting of both ablative and reusable materials. The results indicate that the aeroassisted maneuver is more convenient than a "full propulsive" maneuver in the analyzed case, even considering the increased vehicle mass due to the presence of the heat shield.

Resumo em Inglês:

ABSTRACT: The surface of vulcanized ethylene propylene diene terpolymers (EPDM) was modified by Ar and N2, microwave generated plasma in order to improve adhesion properties. Surface modification was characterized by universal attenuated total reflectance Fourier Transform Infrared (UATR/FT-IR), because it presented lower interference of ingredients of EPDM formulation when compared with other techniques used for the attenuated total reflectance (ATR) to different crystals (ATR/KRS-5 and ATR/Ge). Oxygenated groups were introduced on the surface after treatments which were formed when the activated surface was exposed to the plasma gas. In treatments with nitrogen, oxygen groups and probable nitrogen groups were formed on the surface and could be identified by FT-IR. Reduction in the measurement of the contact angle and an increase in the work of adhesion and in the peel strength (EPDM X Polyurethane (PU)) were observed after the treatment resulted in the improvement of the adhesion properties of the modified surface.

Resumo em Inglês:

ABSTRACT: The success in developing modern aerospace systems addresses competitive subjects as optimization, reduced costs, sustainability, environment, weight, and safety. There is an increased demand for lighter materials such as laminated composites. In order to match the demand of aeronautical companies, the shell structures are very important. The dynamic behavior of composite structures is also essential to improve the potential applications of these materials. The knowledge of the dynamic response of the cylindrical shell structures is an important issue in their design, in which the ply thicknesses are often preestablished and the ply orientations are usually restricted to a small set of angles due to manufacturing constraints. Obtaining the best stacking sequence of laminated shell may lead to a problem of combinatorial optimization. As this problem is hard to be solved, several techniques have been developed. Ant colony optimization is a class of heuristic optimization algorithms inspired by the behavior of real ants, related to their ability to find the shortest path between the nest and the food source. Thus, this paper deals with optimal stacking sequence of laminated cylindrical composite shells with the aim of maximizing their fundamental frequency using this approach. The ant colony algorithm was implemented in Matlab platform and was linked to Abaqus academic version to compute the structural response. Cylindrical shells with and without a cutout geometry were studied. Fundamental frequencies were maximized for both cases, and results were presented and discussed.

Resumo em Inglês:

ABSTRACT: Modern electronic support (ES) systems are descended from systems intended for the detection of small numbers of high-power radar systems, and are thus not suitable for the low-power transmitters and dense signal environments typical of commercial communication networks. A new ES-system architecture is proposed to allow the detection of large numbers of low-power emitters and the estimation of their angle of arrival. The proposed architecture has a number of benefits including versatility, suitability for deployment on airborne platforms, and modularity.

Resumo em Inglês:

ABSTRACT: Contemporary digital systems must necessarily be based on the "System-on-Chip" (SoC) concept. Especially in relation to the aerospace industry, these systems must overcome some additional engineering challenges concerning reliability, safety and low power. An interesting style for aerospace SoC design is the GALS (Globally Asynchronous, Locally Synchronous) paradigm, which can be used for Very Large Scale Integration - Deep-Sub-Micron (VLSI_DSM) design. Currently, the major drawback in the design of a GALS system is the asynchronous interface (asynchronous wrapper - AW) when being implemented in VLSI_DSM. There is a typical AW design style based on asynchronous controllers that provides communication between modules (called ports), but the port controllers are generally subjected to essential hazard, what decreases the reliability and safety of the full system. Concerning to this main drawback, this paper proposes an AW with robust port controller that shows to be free of essential hazard, besides allowing full autonomy for the locally synchronous modules, creating fault tolerant systems as much as possible. It follows the Delay Insensitive (DI) model interacting with the environment in the Generalized Fundamental Mode (GFM) without the need to insert any delay elements. Additional delay elements, although proposed by some previous work found in literature, are not desirable in aerospace applications. The proposed interface allows working on Ib/Ob mode, showing the DI model is more robust than the QDI model and, therefore, it does not need to meet isochronic fork requirements nor timing analysis. Once an interface presenting similar properties was not found in literature, the proposed architecture proved to have great potential of implementation in practical VLSI_DSM designs, including the aerospace ones, once it overcomes the main engineering challenges of this kind of industry.

Resumo em Inglês:

ABSTRACT: Airport noise presents a major environmental impact arising from aircrafts airport activities, being one of the most complex and difficult mitigation problems. From the environmental point of view, airports cause serious problems to the population. Annoyance caused by noise was evaluated from the Day-Night Level (DNL) metrics proposed by Schultz. However, acoustic comfort is assessed separately during the day and at night, because the noise adverse effects are different. In this context, this paper presents a study on sound impact assessment related to noise annoyance caused by aircraft and aims to establish a method to analyze the sound impact on inhabited communities that are in the vicinity of airports. Besides, it proposes reviews available in literature and discusses noise annoyance exposure caused by transportation systems in an evolutive context. The study was based on criteria of evaluation levels panned for comfort of the community according to the Brazilian Standard ABNT/ NBR 10151. Therefore, a fuzzy logic system was developed in order to establish a relationship between the percentage of people highly annoyed by adverse noise effects around the airport, Day Equivalent Sound Level (LAeqD) and Night Equivalent Sound Level (LAeqN) metric descriptors.

Resumo em Inglês:

ABSTRACT: The continued growth of the general aviation fleet demands the need of forever improved preventive methods of failure analysis, in order to reduce the number of incidents or accidents. It has been proved that one possible solution to avoid unsafe conditions is the installation of new avionic systems. This article presents the method named IMFLAR - an Intuitive Method For a Logical Avionics Reliability, an analysis method for avionic systems installations based on a conceptual model of human factors and an artificial neural network application, giving an overview of these installations and analyzing the involved risk factors. This is a new preventive approach that establishes a relationship between unsafe characteristics observed during the installation of avionic systems and an operational database of incidents and accidents, in order to provide a framework to make aviation safer. Additionally, this article describes the steps to obtain the necessary parameters that ought to be used to avoid unsafe conditions for a modification that installs an avionics system in the aircraft.