An Engineering Methodology for Kite Design Copyright c 2010 by J. Breukels Printed by: Proefschriftmaken.nl Printyourthesis.com Published by: Uitgeverij BOXPress,|| Oisterwijk All rights reserved. No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without the prior permission of the author. ISBN 978-90-8891-230-6 Typeset by the author with the LATEX documentation system. Cover design composition made by the author. Author email: [email protected] ii An Engineering Methodology for Kite Design PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Technische Universiteit Delft, op gezag van de Rector Magnificus Prof. ir. K.Ch.A.M. Luyben, voorzitter van het College voor Promoties, in het openbaar te verdedigen op vrijdag 21 januari 2011 om 10.00 uur door Jeroen BREUKELS Ingenieur Luchtvaart en Ruimtevaart geboren te Elst. Dit proefschrift is goedgekeurd door de promotoren: Prof. dr. W.J. Ockels Prof. dr. ir. J.A. Mulder Samenstelling promotiecommissie: Rector Magnificus voorzitter Prof. dr. W.J. Ockels Technische Universiteit Delft, promotor Prof. dr. ir. J.A. Mulder Technische Universiteit Delft, promotor Prof. dr. ir. J.C. Brezet Technische Universiteit Delft Prof. dr. D.J. Rixen Technische Universiteit Delft Prof. M. Milanese Politechnico di Torino Dr. R. Schmehl Technische Universiteit Delft Dr. H. Rebbeck Mutiny kites De volgende bedrijven en instellingen hebben in belangrijke mate financieel bijgedragen aan de totstandkoming van dit proefschrift. The Rotterdam Climate Initiative, Stichting Shell Research, E-on, Provincie Groningen, Energy Delta Institute, Gasunie, Fugro, Rijksuniversiteit Groningen, Gemeente Delft, Gemeente Groningen, Energy Valley, Prolyte Products. ii For my parents Henk en Ineke and my girlfriend Judith iii iv De vlieger Mijn vlieger gaat naar boven, Wat heeft de wind veel kracht! Wie zou het ooit gelooven, Ik trok, met al mijn magt; ’k Heb zoo veel touw gekregen En ’t is er aan besteed; Hij is zoo hoog gestegen, Dat ik hem naauwlijks weet. Ik moet mijn’ vlieger binden, Want anders reis ik meˆe; Waar zal men mij dan vinden, Hij trok mij wis in zee! - ’k Zal op mijn’ vader wachten, Dat die hem naar zich trekt; Ik heb mijn kleine krachten Niet vruchteloos ontdekt. - De wind heeft veel vermogen, Wie kan hem tegen gaan? - Wij zien hier, met onze oogen, Toch niets van zijn bestaan! - Dit is nooit aangewezen; God geeft die kennis niet, Wiens almagt elk moet vreezen, Die ook den wind gebiedt. - Johannes Hazeu Cornelisz ”Kinderspelen, in leerzame gedichtjes” Ten Brink en De Vries, Amsterdam z.j. 2e druk, 1837. v Preface When I first heard of energy generation using large controlled kites that go up thousands of feet, I was struck by a feeling of disbelief. It is simply hard to imagine what such a system would entail. The mental picture I had of a kite was that of a small, square shaped toy which was fragile and crashed every time the wind changed. During the course of my master thesis and later, the work presented in this dissertation, I came to realize the real potential of kites. If anything, my hopes are to communicate this realization to the reader as much as I can. The odd thing is that no one bats an eyelash at the large commercial aircraft that land at Schiphol airport every three minutes with pinpoint precision. We have become both accustomed and dependent to this sight that even a brief period of stagnation in air transport seems to throw the whole world into disarray. It is a testament to the phenomenal achievements of the aviation industry that we have become so blase about our dependence on those planes landing every three minutes. We simply assume they will. We can, because they always do! But when you are at the beach, flying a kite with airplane controls, it doesn’t take long for a crowd to gather and to look on in amazement. My personal experiences at conferences were much the same. The concept of a kite hanging in the sky while you steer it from left to right using a flightstick is something most people have never seen. This very fact shows, with undenyable clarity, the difference in public awareness with regard to airplanes and kites. I myself was a victim of that discrepancy in awareness as well until I started to look at kites as an engineer with an open mind. During my work, I have found no reason why controlled kites should be so rare. From an engineering point of view, a kite is a tethered airplane which adheres to the same laws of physics as airplanes do. The applications for controlled kites are abundantly clear and very diverse. As a result of my publications and videos on the internet I have received a great deal of interest from not just kite companies, but also other large companies who often inquired about the use of kites for a particular application which I myself had never thought of. The potential for kites is now more obvious to me than ever. vii As far as scientific research goes, kites have seen very little so far. This makes the subject of this thesis somewhat of an odd duck. This has its advantages and disadvantages. An advantage is that no matter what you do, it is almost always new. Kites present a largely unexplored field with a lot of potential for researchers. The disadvantage is that, during my work, almost no one was doing similar work which creates an atmosphere of isolation. It makes it more difficult to be accepted to conferences and to get papers published. It seemed that with every presentation, I had to tell the story of the potential of kites all over again in order to convince my audience. However, in all honesty I have to say that I have greatly enjoyed doing so. I am most grateful to my promotor, Prof. Dr. Wubbo J. Ockels, for the opportunity to pursue this research project. His vision is what has made this work possible in the first place and his input during the course of my PhD track has been most valuable. I also would like to thank Dr. Roland Schmehl for his patience in proof reading all that I wrote and his great insight which has helped me a great deal. I am also most grateful to Prof. Dr. Ir. Bob Mulder for believing in this, and I quote: ”exotic project” enough to be involved in such an intense manner. His input has had a significant impact on this work. Lastly, without the support and organizational skills of Nana Saaneh, management assistent at ASSET, none of us at ASSET would be able to do what we do. Much of this work has been made possible by the sponsorship of The Rotter- dam Climate Initiative, the University of Groningen, the Town of Delft, Gasunie, E-on, Fugro, Energy Delta Institute, Stichting Shell Research, Prolyte products, the Town and Province of Groningen and Energy Valley. Without their support, the Laddermill project would not even exist. I owe them my gratitude. For providing support for MSC ADAMS, I am most thankful for Ir. Chris Verheul of Sayfield International. I have thoroughly enjoyed working together with Chris and I would like to thank him for all his effort. I am also thankful for the help provided by Ir. Arend Schwab and Ir. Edwin de Vries on the multi-body simulations. Furthermore, I am most appreciative for the excellent discussions I have had with Peter Lynn of Peter Lynn Kites, Armin Harich from Flysurfer and Dr. Henry Rebbeck of mutiny kites (formerly of FlexiFoil) for sharing their knowledge and experience in the kite industry. Their insights have been most helpful. I also owe a debt of gratitude to Mike Lam and Corneilla Lam of Lam Sails in Hong Kong for producing some of the kite designs that were devised. I would also like to thank Dr. Keith Alexander of the Canterbury University in Christchurch, New Zealand for his hospitality and for sharing his insights with me. During my work I have had the good fortune to work together with a large number of students. I have found the cooperation with students to be both inspi- ring and enjoyable. I am especially grateful to the master students I was given the opportunity to supervise. Edwin Terink, Stefan de Groot, Aart de Wachter, John van den Heuvel, Joep Breuer and Gert-Jan Spierenburg have all made valuable contributions to this thesis. I am also grateful for the cooperation with Lillian viii van Emden, Alberto Saez, Jan Muit, Thomas Frenkel and Rene Oudeman for all their work during their graduation projects. Lastly I want to especially mention Roland Verheul and express my gratitude for all his support during the course of my thesis work. I would like to thank both my parents Henk en Ineke Breukels for all their incredible support during my time in Delft. Without them, everything would have been different. The last words of gratitude go to my sweet girlfriend Judith, for her love, her patience and her unending enthusiasm whilst listening to me rambling on about the wonderful world of kites. Jeroen Breukels 2010 ix Summary An Engineering Methodology for Kite Design Kites have existed for nearly 3000 years [Fadul, 2009], yet they have seen little serious attention from the scientific community. Kites have been of paramount importance during the development of powered flight in the nineteenth century. By the beginning of the twentieth century, the widespread attention of the scien- tific community has made it possible for aeronautical science and technology to grow into a serious field of study.