scispace - formally typeset
Search or ask a question

Showing papers in "Canadian Aeronautics and Space Journal in 2002"


Journal ArticleDOI
TL;DR: Computational Fluid Dynamics (CFD) is increasingly being applied to model turbulent jet flows in practical applications ranging from gas turbine combustion to noise control and thrust augmentation as mentioned in this paper.
Abstract: Computational Fluid Dynamics (CFD) is increasingly being applied to model turbulent jet flows in practical applications ranging from gas turbine combustion to noise control and thrust augmentation....

95 citations


Journal ArticleDOI
TL;DR: The Large Adaptive Reflector (LAR) as discussed by the authors is a concept for a low-cost, large-aperture, wideband, radio telescope, designed to operate over the wavelength range from 2mt o 1.4 cm.
Abstract: A multi-national grouping of radio astronomers has identified the need for a major new instrument, called the Square Kilometer Array (SKA), to be constructed in the coming decade. This giant radio telescope will be 100 times more powerful than any in existence today. The innovative Canadian concept for the underlying design of the telescope, the Large Adaptive Reflector (LAR), is among the best candidates and is well positioned to be adopted by the international community. The LAR is a concept for a low-cost, large-aperture, wideband, radio telescope, designed to operate over the wavelength range from 2mt o 1.4 cm. Theproposed design for the LAR includes two central components. The first is a long focal length, large-diameter parabolic reflector, composed of actuated hexagonal panels, mounted on the ground. The second component is a focal package supported at a height of 500 m by a large helium balloon (aerostat) and a system of three or more taut tethers. The telescope is steered by simultaneously changing the lengths of the tethers with winches (thus changing the position of the feed) and by modifying the shape of the reflector. Simulations have shown that in operating wind conditions, the position of the feed platform can be stabilized to within a few centimetres. This paper gives an overview of the present state of the LAR design, with an emphasis on the airborne subsystem. Construction of a 1/3-scale model of the tethered aerostat subsystem, with a footprint of "only" 0.5 km 2 , is presently underway in Penticton, B.C. It will allow a validation of the underlying design and the study of some fascinating issues in the design and control of this system. Continued on page 240

45 citations


Journal ArticleDOI
TL;DR: A review of thrustvectoring initiatives shows that thrust-vectoring technology is proven to be a proven concept that enhances the projection of aerospace power with many advantages, including improved aircraft m... as mentioned in this paper.
Abstract: A review of thrust-vectoring initiatives shows thrust-vectoring technology to be a proven concept that enhances the projection of aerospace power with many advantages, including improved aircraft m...

39 citations


Journal ArticleDOI
TL;DR: In this article, the authors deal with the high-altitude simulation and testing of upper stage rocket motors with large nozzle area ratios, using second-throat exhaust diffusers (STED).
Abstract: This paper deals with the high-altitude simulation and testing of upper stage rocket motors with large-nozzle area ratios, using second-throat exhaust diffusers (STED). To evaluate the performance ...

32 citations


Journal ArticleDOI
TL;DR: The design of the proposed Galileo system is described in comparison with the existing Global Positioning System (GPS) and availability and accuracy are defined and statistical reliability theory is reviewed.
Abstract: The performance of a Global Navigation Satellite System can be quantified by availability, accuracy, and reliability. The deployment of Galileo by the European Union will provide double the number of navigation satellites currently available to users and offer improvements in accuracy and reliability. This paper briefly describes the design of the proposed Galileo system in comparison with the existing Global Positioning System (GPS). Availability and accuracy are then defined and statistical reliability theory is reviewed. Worldwide availability, accuracy, and reliability estimates for GPS, Galileo, and the combined GPS/Galileo system are obtained by software simulation. The simulation results are presented using Horizontal and Vertical Dilution of Precision as measures of availability and accuracy and maximum Horizontal Position Error due to one undetected blunder as a measure of reliability. The validity of these quantities as measures of accuracy and reliability is discussed and compared with other me...

32 citations


Journal ArticleDOI
TL;DR: A review of Canadian airborne and space-borne hyperspectral Earth observation (EO) activities can be found in this paper, where Canadian progress in applications development, space technology, and ground processing and analysis is discussed.
Abstract: This paper reviews Canadian airborne and spaceborne hyperspectral Earth observation (EO) activities. Civilian uses for hyperspectral imaging include agriculture, environment, fisheries (including aquaculture), forestry, geoscience, disaster mitigation, and other areas. Canadian progress in applications development, space technology, and ground processing and analysis is discussed. Current and future hyperspectral satellite missions are listed, along with Canadian participation. The paper concludes by outlining the Canadian Space Agency's current plans to develop a spaceborne hyperspectral imager.

25 citations


Journal ArticleDOI
TL;DR: The methode d'essai FLV as discussed by the authors is a methode classique de test vibratoire and decrit en detail quelques caracteristiques of the methode.
Abstract: Lors de tests vibratoires conventionnels de materiel spatial, l'acceleration imposee a la base de l'unite mise a l'essai est controlee selon des specifications habituellement tires de l'acceleration d'interface de l'unite a des niveaux avances d'assemblage. Depuis maintenant 30 ans, cette approche conventionnelle de mise a l'essai du materiel est reconnue pour surtester les elements a leurs propres frequences naturelles. Au cours des dernieres annees, le JPL de la NASA a ete le chef de file dans le developpement et la mise en oeuvre d'une nouvelle methode de test vibratoire ou la force d'interface est aussi controlee (FLV pour Force Limited Vibration testing). En plus de controler l'acceleration imposee, la methode d'essai FLV mesure les forces exercees entre l'element teste et le pot vibrant et limite ces dernieres. Cette publication traite du probleme du surtestage associe a la methode classique de test vibratoire et decrit en detail quelques caracteristiques de la methode d'essai FLV. En outre, cet article presente quelques resultats de l'effort concerte de l'ASC et de EMS visant l'etude et la demonstration de la methode d'essai FLV appliquee a des elements simples.

16 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present adaptive finite element methods as a means of achieving verification of codes simulations (obtaining numerical solutions with controlled accuracy). Validation of these grid-independent solutions is then performed by comparing predictions to measurements.
Abstract: This paper presents adaptive finite-element methods as a means of achieving verification of codes simulations (obtaining numerical solutions with controlled accuracy). Validation of these grid-independent solutions is then performed by comparing predictions to measurements. We adopt the standard accepted definitions of verification validation (AIAA 1998; Roache 1998). Mesh adaptation is used to perform the systematic rigorous grid-refinement studies required for both verification validation in CFD. This ensures that discrepancies observed between predictions measurements are due to deficiencies in the mathematical model of the flow. Issues in verification validation are discussed. The paper presents examples of code verification by the method of manufactured solution. Examples of successful unsuccessful validation show that agreement with experiment is achieved only with a good mathematical model of the flow physics combined with accurate numerical solutions of the differential equations. The paper emphas...

16 citations


Book ChapterDOI
TL;DR: The MOST (Microvariability and Oscillations of STars) astronomy mission has been chosen by the Canadian Space Agency's Small Payloads Program to be Canada's first space science microsatellite as discussed by the authors.
Abstract: The MOST (Microvariability and Oscillations of STars) astronomy mission has been chosen by the Canadian Space Agency’s Small Payloads Program to be Canada’s first space science microsatellite. It is currently planned for launch in early 2002 to conduct long-duration stellar photometry observations in space. A major science goal is to set a lower limit on the age of several nearby “metal-poor sub-dwarf” stars, which may in turn allow a lower limit to be set on the age of the Universe. To make these measurements, MOST will incorporate a small (15 cm aperture), high-photometricprecision optical telescope developed by the University of British Columbia. A direct benefit of meeting the formidable challenges of the MOST mission is the creation of a versatile spacecraft bus that can be used for a multitude of science and technology missions that could not be performed previously using a spacecraft of similar size and cost. Moreover, the expertise now exists for collaboration with the European community on low-cost space technology projects.

15 citations


Journal ArticleDOI
TL;DR: In this paper, a morphogenetic model is used to predict the shape and mass forming on a cylinder under rime and glaze conditions, taking into account the variation of local cloud-droplet collision efficiency and local heat transfer around the cylinder surface.
Abstract: In this paper, we propose and illustrate a new modelling approach to tackle the challenging problem of in-flight icing prediction. With this new approach, termed morphogenetic modelling, we attempt to predict the structural details of aircraft ice accretions by emulating the behaviour of individual fluid elements, including interception, surface flow, freezing, and shedding. A two-dimensional, morphogenetic model is used here to predict the ice-accretion shape and mass forming on a cylinder under rime and glaze conditions. The model takes into account the variation of local cloud-droplet collision efficiency and local heat transfer around the cylinder surface. It simulates such common icing features as horn formation, runback, and water shedding.We complement the numerical simulation with an analytical model for cylinder icing that is based on a simple form of the mass and heat conservation equations. This analytical investigation allows us to define a new dimensionless ratio, the runback factor, which is...

13 citations


Journal ArticleDOI
TL;DR: In this article, detailed measurements of the unsteady periodic flow characteristics were taken in a radial vaneless diffuser using hot-wire miniature probes and several static and dyna...
Abstract: Detailed measurements of the unsteady periodic-flow characteristics were taken in a radial vaneless diffuser. The measurements were made using hot-wire miniature probes and several static- and dyna...

Journal ArticleDOI
TL;DR: The Polar Outflow Probe (POP) as discussed by the authors is a mission of the International Astronautical Satellite Association (IASA) which is a bord of a mictosatellite.
Abstract: Ce memoire presente le developpement et les objectifs scientifiques de la sonde de mesure de l'ecoulement du plasma dans le vent polaire (POP pour Polar Outflow Probe). La mission qui sera dirigee par l'Institut de recherche spatiale de l'Universite de Calgary se deroulera a bord d'un mictosatellite. La mission POP a ete selectionnee dans le cadre du concours des etudes de phase A de l'avis d'offre de participation de 1996 lance par le Programme des petites charges utiles de l'ASC. Le projet a ensuite ete selectionne pour etre developpe a titre de « mission cruciale de reserve ». L'objectif scientifique principal de la mission POP est d'etudier les processus d'ecoulement plasmique et atmospherique dans l'ionosphere polaire et la haute atmosphere, entre 300 et 1500 km d'altitude, ou la population atmospherique de particules neutres est en grande partie inexploree et la population de particules plasmiques est sous-exploree. La mission POP vise egalement a etudier les caracteristiques a petite echelle de l'ecoulement plasmique dans l'ionosphere polaire et d'analyser, a des resolutions inedites, les processus plasmiques qui se produisent a petite et moyenne echelles. Elle vise aussi a etudier l'occurrence de l'ejection de particules neutres dans la haute atmosphere. La mission POP sera embarquee dans un microsatellite place sur orbite elliptique a inclinaison prononcee. Le microsatellite sera constitue d'une plate-forme de 70 kg mesurant 0,5 m 3 et comprenant une charge utile de 25 kg composee d'instruments scientifiques. L'orbite sur laquelle evoluera ce satellite sera elliptique, avec un perigee nominal de 300 a 500 km, un apogee de 1000 a 1500 km et une inclinaison variant entre 65 et 110 degres. Afin d'atteindre l'orbite elliptique a grande inclinaison, les organisateurs ont prevu lancer le satellite POP en qualite de charge utile secondaire sur une orbite basse (LEO) pour ensuite le placer sur son orbite finale a l'aide de propulseurs integres. La charge utile scientifique sera constituee de cinq instruments, soit un spectrometre imageur ultra-rapide servant a a determiner la masse, l'energie et la distribution angulaire des particules ioniques, un spectrometre a temps de vol servant a determiner la masse et la vitesse des particules neutres, un imageur d'electrons suprathermiques, un imageur auroral et un recepteur radio. Ces instruments pourront ainsi mesurer depuis une plate-forme orbitale la vitesse des ions, des electrons et des particules neutres, a des resolutions spatio-temporelles inedites. De plus, la charge utile sera constituee d'un magnetometre a vanne de flux et d'un recepteur GPS differentiel qui sera utilise pour determiner l'attitude et la position de l'engin spatial, et pour mesurer scientifiquement les perturbations du champs magnetique et les irregularites de l'ionosphere. L'imageur auroral et le spectrometre de mesure de la masse des particules neutres sont deux nouveaux instruments actuellement en developpement a l'Universite de Calgary et a a l'Institut des sciences spatiales et aeronautiques (ISAS pour Institute of Space and Astronautical Science), respectivement. Les autres instruments sont des versions ameliorees ou modifiees d'instruments ayant deja ete utilises dans le cadre de mission spatiales canadiennes ant erieures.

Journal ArticleDOI
TL;DR: In this article, the influence of landing-gear design on ground resonance was investigated with the aid of finite-element software, and the influence was shown that landing gear design can influence ground resonance.
Abstract: The influence of landing-gear design on a ground-resonance phenomenon is investigated with the aid of finite-element software. Ground resonance is a vibration phenomenon that occurs at certain roto...

Journal ArticleDOI
TL;DR: In this article, the authors describe the tests undertaken to determine the dipole moments of a magnetic torquer rod and present the test methodology, experimental setups, and test results in detail.
Abstract: This paper describes the tests undertaken to determine the dipole moments of a magnetic torquer rod. Test methodology, experimental setups, and test results are presented in detail. The dipole mome...

Journal ArticleDOI
TL;DR: In this article, the authors compare le filtre de Kalman etendu (qui etait traditionnellement utilise pour determiner l'attitude d'un engin spatial) a un filtre relativement nouveau.
Abstract: Les exigences en matiere de conception et fabrication des engins spatiaux sont en pleine effervescence. Il est de plus en plus preferable de construire des petits engins spatiaux peu couteux et tres performants(pensez seulement au telescope spatial qui doit poursuivre les etoiles avec precision). L'utilisation de materiaux moins couteux reduirait le rendement de l'engin spatial, mais cet effet peut etre contre en ayant recours a de meilleures techniques de commande de l'appareil et d'evaluation des couts du projet Ce memoire compare le filtre de Kalman etendu (qui etait traditionnellement utilise pour determiner l'attitude d'un engin spatial) a un filtre relativement nouveau, le filtre predictif non lineaire. Il est demontre que dans certaines conditions, le filtre predictif non lineaire est plus performant que le filtre de Kalman etendu, Certaines de ces conditions (notamment l'utilisation de detecteurs de vitesse) sont incompatibles avec les exigences portant sur la robustesse de l'appareil par rapport a l'estimation initiale des probabilites d'erreur.

Journal ArticleDOI
TL;DR: In this article, a new coupled wake-based CFD method was used to include realistic wake effects in CFD solutions for rotor flow in hover, and the analytical method for predicting hovering rotor wake was described to investigate the motion of the helical tip vortex.
Abstract: A new coupled wake – CFD method is used to include realistic wake effects in CFD solutions for rotor flow in hover. The analytical method for predicting hovering rotor wake is described to investigate the motion of the helical tip vortex. Beginning with the generalized wake model, a semi-empirical correction for the vortex core effect on rotor wake is made. Then on the condition of circulation and wake geometry convergence, the free wake calculation is accomplished. Finally, Euler–Navier–Stokes equations are solved for transonic rotor flow employing Jameson's finite-volume explicit Runge-Kutta time-stepping scheme. The results are compared with the respective references and experimental data.

Journal ArticleDOI
TL;DR: This paper presents the flight- software development framework created for the Generalized FLight Operations Processing Simulator (GFLOPS) testbed, which applies principles of object-oriented design to separate sub-system software functions into protected, quasi-independent modules.
Abstract: To maximize the profitability of modern satellites, designers must invest their spacecraft with both capability and reliability. On-board, autonomous software holds the promise of greatly enhancing spacecraft abilities, yet software glitches have been directly to blame for recent, highly publicized failures. This paper presents the flight- software development framework created for the Generalized FLight Operations Processing Simulator (GFLOPS) testbed. Based upon a robust, commercial, real- time operating system, the methodology applies principles of object-oriented design to separate sub-system software functions into protected, quasi-independent modules. The flight software modules are coupled to simulation modules, which provide high-fidelity, real-time, representations of system hardware and dynamics. The GFLOPS approach provides tools and a methodology suitable for rapid flight software development. Since the basic implementation of the framework does not rely on any advanced techniques such as autonomy, it can be used in both conservative and aggressive engineering programs. Focus applications include an MIT-designed formation flying experiment (SPHERES) and a U.S. Air Force- funded distributed satellite mission (TechSat 21). continued on page 52

Journal ArticleDOI
TL;DR: In this article, the effects of skirt material damping on heave dynamics of an air-cushion-vehicle bag-and-finger skirt is investigated, and the effect of skirt viscoelastic properties is investigated.
Abstract: An investigation of the effects of skirt-material damping on heave dynamics of an air-cushion-vehicle bag-and-finger skirt is described. Previous investigations of skirt viscoelastic phenomena are ...

Journal ArticleDOI
TL;DR: The degree to which hardware can be emulated using the development of the attitude control system for the MOST microsatellite as an example is investigated and a trade study is presented that indicates when the cost of programming the emulator outweighs the benefits, and a law of diminishing returns applies.
Abstract: In small-satellite projects on short schedules, there is often insufficient time to develop new hardware and subsequently write software once the hardware is tested and ready. In some cases, it is not possible to build a satellite and develop new hardware for that same satellite. However, if the target functionality and performance of the new hardware elements are known together with their interfaces to other parts of the system, then emulating these elements may be useful if the effort involved in doing so is kept to a minimum. Ideally, the proper hardware interfaces should be implemented, and the purpose of the emulation should be to act as a substitute for the missing hardware so that flight code can be developed concurrently with the hardware. The use of the real-time development system RT-Lab™ (RT-Lab is a trademark of Opal-RT), which combines both software-based emulation and customized hardware interfaces, provides a flexible environment to develop embedded software early in the development cycle of a small satellite. As hardware elements become available, they can be interfaced with the real-time system, seamlessly replacing the software modules previously simulating their performance. This paper investigates the degree to which hardware can be emulated using the development of the attitude control system for the MOST microsatellite as an example. A trade study is presented that indicates when the cost of programming the emulator outweighs the benefits, and a law of diminishing returns applies. A level of hardware emulation is recommended that facilitates the early development of flight code, but beyond which only the actual hardware should be used. continued on page 88

Journal ArticleDOI
TL;DR: In this article, the authors describe the design and implementation of the horizontal configuration used during design of the BOLAS (Bi-static Observations with Low-Altitude Satellites) rotating tethered satellite configuration.
Abstract: Two configurations of ground tests may be envisaged to provide experimental data to enhance dynamic modelling of tethered satellite configurations: (a) a vertically suspended tether and (b) a horizontally suspended tether. This paper describes the design and implementation of the horizontal configuration used during design of the BOLAS (Bi-static Observations with Low-Altitude Satellites) rotating tethered satellite configuration. The merits of the horizontal and vertical configurations, in the context of rotating tethered satellites, are compared. Large-scale, room-temperature experimental tests emulating the in-orbit dynamic state are described, in which a SPECTRA1000 ® /acrylic tether is suspended horizontally and attached to a pendulum-supported sub-satellite mass. Tension variation due to gravitational cable sag effects is reduced by supporting the tether at intermediate points. The stiffness and structural damping properties are deduced from a cable model that accounts for tether tension variation due to gravitational cable sag effects. Small-scale laboratory tests of tether samples at cryogenic temperatures are conducted to establish the temperature dependence of the tether-material properties. Tether stiffness and damping properties at orbital temperatures are estimated using the experimental data from both large- and small-scale tests. The in-orbit loss of rotation rate of the BOLAS mission due to the gravitygradient-induced longitudinal stretching of the tether is estimated by applying the experimentally determined tether stiffness and damping properties to previously determined equations of orbital motion. continued on page 98

Journal ArticleDOI
TL;DR: In this paper, the aerodynamic design and development of a new single-slotted flap for the Bush Hawk XP was described, and flight test results were presented for the new flap.
Abstract: The Bush Hawk XP, which is produced by Found Aircraft of Canada, is a small, piston-engined utility transport aircraft suitable for bushplane operations. The original version was made in the 1960s, and it uses a sealed, plain hinged flap. In the latest production version the gross weight is increased substantially, necessitating an improved flap design to achieve better airfield distances and climb performance.This paper describes the aerodynamic design and development of a new single-slotted flap for the Bush Hawk. The flap shape and locations when deflected were optimized using modern CFD methods, and wind tunnel tests were bypassed. The features of the flap aerodynamic design, the aircraft structure, and the flap drive systems are described. Flight test results are presented for the Bush Hawk with the new flap; they show outstanding performance in its category.

Journal ArticleDOI
TL;DR: The David Florida Laboratory is Canada's National Facility for assembly, integration, and testing of space and non-space hardware as mentioned in this paper, and three main test facilities exist at the facility.
Abstract: The David Florida Laboratory is Canada's National Facility for assembly, integration, and testing of space and non-space hardware. This paper outlines the three main test facilities existing at the...

Journal ArticleDOI
TL;DR: In this paper, the authors present an Optical Intersatellite link (OISL) terminal design that has the flexibility to meet the requirements of a wide range of potential customers.
Abstract: This paper presents an Optical Intersatellite Link (OISL) terminal design that has the flexibility to meet the requirements of a wide range of potential customers. The program concentrated on the development of the terminal Optical Front End (OFE). The OFE acts as the interface between a fiber-optic communication sub-system and free-space. It finds and tracks the partner satellite, and then maintains a full duplex optical communication link with that partner; 1550 nm is the chosen communication wavelength because of its compatibility with established terrestrial standards. However, the use of all metal, all reflective optics permits the choice of other wavelengths. This paper reviews the terminal architecture and the design of the key OFE components. At the heart of the OFE resides the Afocal Optical Assembly (AOA), positioned between the terminal's telescope and the fiber-optic subsystem. The AOA is essentially a mini-OFE unto itself. It is the common element in all variations of the terminal design. For...

Journal ArticleDOI
TL;DR: The Atmospheric Chemistry Experiment (ACE) is a solar occultation space science mission whose overarching goal is to measure and understand the chemical and dynamical processes that control the solar occultations as mentioned in this paper.
Abstract: The Atmospheric Chemistry Experiment (ACE) is a solar occultation space science mission whose overarching goal is to measure and to understand the chemical and dynamical processes that control the

Journal ArticleDOI
TL;DR: In the past four decades, Canadian scientists and their industrial partners have made major contributions to both the technology of auroral imaging and to the advancement of knowledge through the development of knowledge as discussed by the authors.
Abstract: Over the past four decades, Canadian scientists and their industrial partners have made major contributions to both the technology of auroral imaging and to the advancement of knowledge through the