This thesis investigates the mechanisms behind the control of a typical two line kite, where the lines are attached to the kite side by side. This arrangement gives the kite flyer the ability to apply a roll angle to the kite, which then results in a yawing motion. The reason for this yaw rotation has not been adequately described previously. The definitions of roll and yaw for a kite have been re-defined to match the real world behaviour of the kite-bridle-line system. Specifically, these are defined as rotations relative to the lines rather than the kite itself. This detail has been neglected in previous research, and has a significant effect on the turning behaviour of a kite. A static model of a kite represented by flat disks was created. This model allows the out of balance forces and moments to be found for a kite when it is held at any position. When the kite is held with a roll angle applied, the disk angles of attack become unequal. This causes a change in the magnitude, direction, and point of action of the aerodynamic forces on each disk, which can lead to a yaw moment. While this does not give a complete picture of how a kite turns, it does explain one of the two mechanisms that cause a kite to begin to yaw when a roll angle is applied. The other mechanism is due to the velocity of the roll rotation, and is out of the scope of this thesis since a dynamic analysis would be required. The static model showed that any variation to kite geometry or any parameter that affects the equilibrium position of the kite will affect turning response. The most important of these parameters for a simple kite represented by two disks is the dihedral angle. A minimum negative dihedral angle (or anhedral) is required for a kite to turn in the expected direction when a roll angle is applied. The value of the minimum anhedral angle required for this behaviour varies with other parameters, but is generally between 8° and 20°. Other parameters such as bridle geometry also affect the turning response of a kite, primarily because they alter the equilibrium positions of the kite and line. Altering these equilibrium positions has a strong effect on turning response, since it changes the initial disk angles of attack. Additionally, if the kite and line are not aligned perpendicular to each other (which is a rare condition for a kite) a roll angle further changes the disk angles of attack, since the roll angle is applied about an axis relative to the line rather than the kite. An investigation into the effect of varying wind velocity on turning response showed that it has an important effect. Some kites will reverse their response to a given roll angle at some wind velocities, which could make the kite very difficult to control. Additionally, some kites can alter their equilibrium positions sharply with wind velocity, again causing varying turning behaviour as the wind conditions change. Future work should examine the dynamic turning response of kites. A dynamic simulation could be used to examine how the turning response of a kite is influenced by the rate at which a control input is applied. Additionally, the behaviour of the kite once the initial turning movement has begun could be assessed.

Thesis (M.S.)--Humboldt State University, 2007. / Includes bibliographical references (leaves 43-47). Also available via Humboldt Digital Scholar.

"This research focuses on studying the feasibility of tethered undersea kite (TUSK) systems for power generation. Underwater tethered kite systems consist of a rigid wing that moves in a circular or figure-8 path below the surface. The tether can connect to a platform mounted either on the surface or anchored to the seafloor. On the kite is a turbine that extracts energy from the kite’s forward motion, which has the potential to be several times the current velocity. This speed multiplication combined with the density increase of water as opposed to air is one of the main benefits of this class of systems over wind turbines. A scale-model TUSK kite was designed. Testing was conducted in a water flume at Alden Research Labs (ARL). Model scale factors were determined from a real world prototype TUSK system currently in commercial development. The scale-model kite was primarily constructed out of ABS plastic using 3D printing rapid prototyping methods. Other components of the system were either repurposed from prior projects or constructed with traditional methods. Testing was conducted at current speeds of 0.15 m/s, 0.31 m/s, and 0.46 m/s; kite pitch angles of 80?, 85?, and 90?; and over circular and figure 8 trajectory shapes. Data collected included the azimuth and declination angles of the rigid tether as well as the power output of the generator on board the kite. Filtering techniques were employed on the data to generate graphs of kite position, velocity, and output for analysis. Relationships between current velocity, kite velocity, kite pitch angle, and power output have been measured. Inaccuracies in the model and areas for improvement in future work have been identified."

This thesis has its starting point in an existing computer model of an electricity generating kite, from Heidelberg University. The modelled kite has an area of 500 m2 and is tethered to a generator at sea. A control unit steers the kite in an optimised trajectory. The design and trajectory that maximise mean power output per loop had been found using the optimisation software MUSCOD-II. Firstly, the model is investigated in order to find possible adjustments to make it closer to reality. Then a method to take the economic aspect into account in the optimisation has been developed. The most important findings in the model survey concerned wind speed. The original model overrated the wind speed at high altitudes and it used a mean wind speed instead of including yearly variations. Adjustments are made and a new objective function aiming at maximising the yearly average power output per invested Euro is used. Furthermore, the revised model has a preset wind speed range within which the kite can operate, and a maximum power output of the generator (the nominal power) which is found through optimisation with respect of cost. Cable strength and other production limitations are included as well. Using cost estimations for relevant parts, the revised optimisation model results in a system with a tethering cable about half the original length, and a steadier power output over the loop. The yearly production sums up to 16.8 GWh, as compared to the original model which would have given 42.9 GWh yearly.

The Baramon is a handmade kite from the Gotô Islands in Nagasaki Prefecture, Japan. Its motif features a fierce ogre biting an ornate warrior's helmet. Today, the Baramon is widely recognized as a unique Gotô product. However, nearby regions of Nagasaki also produce similar traditional kites. How and why was the Baramon's exclusive connection to Gotô cultivated and how does it affect notions of regional identity in contemporary Gotô? This thesis argues that while the Baramon belongs to the broader repertoire of Nagasaki kite types, the people of Gotô have gradually appropriated it as a regional symbol by selectively associating particular aspects of Gotô culture and history with the kite's iconography and shape. Consequently, it has become an officially recognized emblem of Gotô. Moreover, the playful transmutation of the Baramon continues in the tourist industry's continuous efforts to revitalize Gotô's image by promoting local history and culture.

Les cerf-volants existent depuis l'Antiquité, mais leur utilisation comme moyen de récupération de l'énergie éolienne est relativement récente. Pourtant, leur légèreté et leur capacité à aller chercher les vents forts et réguliers en altitude en font un dispositif compétitif pour produire de l'électricité ou pour tracter des navires commerciaux. En effet, un cerf-volant peut espérer produire plus de $10$ kW.m$^{-2}$. Cela implique qu'un cerf-volant de $1000$ m$^2$ pourrait apporter une assistance substantielle (typiquement $20$ $%$) à la propulsion des plus gros cargos actuels. Cette thèse s'intéresse à deux problèmes associés au développement de tels cerf-volants:Comment les faire décoller et atterrir de manière autonome et sans risque de les perdre? L'utilisation de cerf-volants à structure gonflable donne l'avantage d'avoir une aile rigide et légère en vol et compacte lors de son stockage. Pour aider au dimensionnement de ces cerf-volants, nous étudions dans le première partie de la thèse le comportement des structures gonflables soumis à des chargements statiques et dynamiques.Comment s'assurer de son vol stable? Une fois qu'il a décollé, un cerf-volant doit pouvoir rester en l'air. Il apparait cependant que dans certaines conditions, les cerf-volants entrent dans des oscillations de grandes amplitudes avant de tomber au sol. Grâce à des expériences en soufflerie, nous étudions dans la seconde partie de la thèse l'origine de ces oscillations et les conditions à réunir pour les éviter. / Kites exist since ancient times, but their use as wind energy harvesting device is relatively recent. Still, their light weight and ability catch strong and steady winds in altitude make them a competitive mean to generate electricity or to tow commercial ships. Indeed, a kite can typically produce $10$ kW.m$^{-2}$. This implies that a $1000$ m$^2$ kite could provide substantial assistance ($20$ $%$) to the propulsion of the biggest current tankers. This thesis focuses on two issues associated with the development of such kites:How can one perform autonomous take off and landing without the risk of losing them? Kites with inflatable structures take advantage rigidity and lightness during flight and from high compactness during storage. It also allows them to float if they crash on the ocean. To design those kites, we study in the first part of the thesis the behavior of inflatable structures under static and dynamic loadings.How can one achieve a stable flight? Once it takes off, it appears that under certain conditions, the kites undergo large amplitude oscillations that eventually lead to their fall onto the ground. Using wind tunnel experiments, we examine in the second part of the thesis the origin of these oscillations and the conditions which prevent them from occurring.

Sailing has gone from being an effective mode of transport to now only be a hobby. The main reason for this is that the sailboats have not had the same rate of development as other modes of transport. The main reason for this is that the sail is attached to a mast which creates a large heeling angle on the boat. Volare's solution to the problem is to use a kite sails instead of the traditional sail making so that torque is minimized considerably, which in turn means that you can reach significantly higher speeds. Volare has developed a unique solution for launch of a kite on sail boats, which contains several patented solutions. The product project team has developed stands up well against the competition in the market as it is easy to use, designed to launchas by only one person and that it takes up little space on the boat when not in use. With a less heel and higher speed are Volare on the way to creating the future way to sail.

No abstract available. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1981.

O gavião-de-pescoço-branco Leptodon forbesi Swann, 1922, endêmico da Mata Atlântica do Centro Pernambuco, é uma espécie cujo status taxonômico ainda é controverso. Autores como Swann (1922 e 1945), Teixeira et al. (1987) e del Hoyo (1994) consideram a espécie como válida, enquanto que outros, como Grossman e Hamlet (1964), Brown e Amadon (1968), Blake (1977) e Sick (1994) optam por considerá-la como uma variante morfológica do gavião-de-cabeça-cinza L. cayanensis. As diagnoses tradicionais de L. forbesisão as coberteiras inferiores das asas, brancas ao invés de negro; píleo cinza; lados do pescoço brancos; ápice das escapulares, manto e rêmiges esbranquiçados; e a cauda com uma larga faixa branca (Swann 1945; Hellmayr e Conover 1949; Pinto 1964). O presente trabalho teve como objetivos estudar e descrever a variação morfológica e morfométrica de L. cayanensis, e testar a validade dos táxons componentes deste complexo, com especial atenção para o táxon L. forbesie sua distribuição geográfica. Foram analisados 128 espécimes do gênero Leptodon, provenientes do México até o estado do Rio Grande do Sul, Brasil. Dados morfométricos foram obtidos e analisados para se avaliar diferenças entre os sexos, o polimorfismo de coloração nas plumagens dos juvenis, e as subespécies propostas por Swann (1922) para L. cayanensis. Além disso, caracteres de plumagem também foram analisados para se testar a validade de L. forbesi. Concluiu-se que há dimorfismo sexual em L. cayanensis, sendo as fêmeas de maior porte (I); que ocorrem duas, e não três, fases de coloração nas plumagens juvenis de L. cayanensis (II); que as subespécies propostas por Swann (1922) para L. cayanensis não são válidas, sendo a variação geográfica do porte mais bem explicada por um gradiente em resposta ao módulo da latitude, como previsto pela Lei de Bergmann (III); e que a espécie L. forbesié um táxon válido, com base nos caracteres da coloração das penas coberteiras inferiores e da borda de ataque das asas, brancas em L. forbesie pretas em L. cayanensis, do contraste entre a coloração ventral das rêmiges, sendo as primárias escuras e as secundárias mais claras em L. forbesi, e da coloração das penas da região do pescoço, brancas em L. forbesie cinzas em L. cayanensis (IV). Desta forma, L. forbesi constitui mais uma espécie endêmica do Centro Pernambuco de Endemismo. / The White-collared (or Forbes) Kite Leptodon forbesi Swann, 1922 is an endemic raptor of the Centro Pernambuco, the northernmost portion of the Atlantic Forest, in Northeastern Brazil, and its taxonomic status is still a case of controversy. It is considered a valid species by Swann (1922, 1954), Teixeira et al. (1987) and del Hoyo (1994), whereas Grossman and Hamlet (1964), Brown and Amadon (1968), Blake (1977) and Sick (1994) opt to consider it a morphological variant of the widespread Grey-headed Kite L. cayanensis. The traditional diagnoses of L. forbesiare the underwing coverts, white instead of black; grey pileum; white collar; white tip of quills, mantle and scapular feathers; and a wide white band on both sides of the tail (Swann 1945; Hellmayr and Conover 1949; Pinto 1964). The present study aims to analyse and describe the morphological and morphometrical variation in L. cayanensis, and to test the validity of taxa within the complex, with a special interest in L. forbesiand its geographical distribution. 128 specimes of the genus Leptodon, from Mexico to Southern Brazil, were studied. Morphometrical data was obtained and analysed to evaluate differences between sexes, colour polymorphism in the juvenile plumage, and the subspecies described by Swann (1922) for L. cayanensis. Plumage characters were also studied to test the validity of L. forbesi. We conclude that L. cayanensis shows sexual dimorphism, the females being larger (I); that there are two, not three, coloration morphs in the juvenile plumages of L. cayanensis (II); that the subspecies described by Swann (1922) for L. cayanensis are invalid, the geographical variation in size better explained as a response to latitude module, as predicted by Bergmanns Rule (III); and that the species L. forbesi is a valid taxon, based on the coloration of underwing and leading edge coverts, white in L. forbesi and black in L. cayanensis; on the coloration of the ventral side of the rêmiges, with a contrast between dark primaries and lighter secondaries in L. forbesi; and on the collar coloration, white in L. forbesiand grey in L. cayanensis (IV). Therefore, L. forbesi constitutes another endemic and endangered species of the Centro Pernambuco, in the Brazilian Atlantic Forest.

Ocean currents and tidal energy are significant renewable energy resources, and new concepts to extract this untapped energy have been studied in the last decades. Tethered undersea kite (TUSK) systems are an emerging technology which can extract ocean current energy. TUSK systems consist of a rigid-winged kite, or glider, moving in an ocean current. One proposed concept uses an extendable tether between the kite and a generator spool on a fixed or floating platform. As the kite moves across the current at high speeds, hydrodynamic forces on the kite tension the tether which extends to turn the generator spool. Since the TUSK system is a new technology, the process of bringing a TUSK design to commercial deployment is long and costly, and requires understanding of the underlying flow physics. The use of computational simulation has proven to be successful in reducing development costs for other technologies. Currently, almost all computational tools for analysis of TUSK systems are based on linearized hydrodynamic equations in place of the full Navier-Stokes equations. In this dissertation, the development of a novel computational tool for simulation of TUSK systems is described. The numerical tool models the flow field in a moving three-dimensional domain near the rigid undersea kite wing. A two-step projection method along with Open Multi-Processing (OpenMP) on a regular structured grid is employed to solve the flow equations. In order to track the rigid kite, which is a rectangular planform wing with a NACA-0012 airfoil, an immersed boundary method is used. A slip boundary condition is imposed at the kite interface to decrease the computational run- time while accurately estimating the kite lift and drag forces. A PID control method is also used to adjust the kite pitch, roll and yaw angles during power (tether reel-out) and retraction (reel-in) phases to obtain desired kite trajectories. A baseline simulation study of a full-scale TUSK wing is conducted. The simulation captures the expected cross-current, figure-8 motions during a kite reel-out phase where the tether length increases and power is generated. During the following reel-in phase the kite motion is along the tether, and kite hydrodynamic forces are reduced so that net positive power is produced. Kite trajectories, hydrodynamic forces, vorticity contours near the kite, kite tether tension and output power are determined and analyzed. The performance and accuracy of the simulations are assessed through comparison to theoretical estimations for kite power systems. The effect of varying the tether (and kite) velocity during the retraction phase is studied. The optimum condition for the tether velocity is observed during reel-in phase to increase the net power of a cycle. The results match theoretical predictions for tethered wind energy systems. Moreover, the effect of the tether drag on the kite motion and resulting power output is investigated and compared with the results of the baseline simulation. The kite drag coefficient increases by 25% while the effect of the tether drag is included into the baseline simulation. It affects the trajectory and the velocity of the kite. However, it has a small effect on the power generation for the proposed concept of TUSK system.