Published version of Ph.D. Thesis - University of Groningen; the work is divided into three parts; the first deals with ethnographic evidence and a general discussion of the physical properties of boomerangs; the second part with the aerodynamics of boomerangs by mathematical and experimental investigation; the third part with the theoretical basis of motion involved in the movement of boomerangs; in the first part the section dealing with ethnographic evidence includes a discussion of types of Australian boomerangs, the distribution, the morphology and manufacture, the throwing of boomerangs and the function of the objects in the past and today; three further sections discuss the use of boomerangs outside Australia and this is concluded with a brief discussion of the origin of boomerangs; an extensive bibliography on boomerangs ends this section; the other two theoretical sections also contain bibliographies.

More frisbees are sold each year than baseballs, basketballs and footballs combined. Yet these familiar flying objects have subtle and clever aerodynamic and gyrodynamic properties which are only recently being documented by wind tunnel and other studies. In common with other rotating bodies discussed in this readily accessible book, they are typically not treated in textbooks of aeronautics and the literature is scattered in a variety of places. This book develops the theme of disc-wings and spinning aerospace vehicles in parallel. Since many of the examples are recreational, anyone who enjoys these activities will likely find it profitable and enjoyable. In addition to spinning objects of various shapes, several exotic manned aircraft with disc planforms have been proposed and a prototypes built – these include a Nazi ‘secret weapon’ and the De Havilland Avrocar, also discussed in the book. Boomerangs represent another category of spinning aerodynamic body whose behavior can only be understood by coupling aerodynamics with gyrodynamics. The narrative, supported by equations and graphs, explains how the shape and throw of a boomerang relates to its trajectory. The natural world presents still other examples, namely the samaras or ‘seed-wings’ of many tree species, which autorotate during their descent, like a helicopter whose engine has failed. The flight performance of these spinning wings directly affects the dispersal and thus the evolutionary competitiveness of the trees concerned. Samara-type configurations are also considered for instrumentation and other payload dispersal applications. In short, the book discusses a range of familiar, connected, but largely undeveloped, topics in an accessible, but complete, manner. From the reviews of the first edition: "In his fascinating book Spinning Flight, Ralph Lorenz provides a rich feast of ... examples of spinning bodies ... . The book is well organized ... . The discussion in the book ... should be accessible to readers with some elementary understanding of aerodynamic principles. For the expert, the book is full of open problems ... . Its scope is extensive ... . In this respect, there may be something for everyone within its attractively designed cover ... ." (H. K. Moffatt, Nature, Vol. 444, December, 2006) "If you liked physics at school, then this book is for you. It concerns itself with flying objects that spin through the air, and even tells you how to impress your friends with the biomechanics of Frisbees. ... there is plenty of information at all levels, and the book has a wealth of detail that only an aerospace engineer like Lorenz could have come up with." (Len Fisher, BBC Focus, February, 2007)

Explains how to build, perfect and troubleshoot paper boomerangs.

Describes the traditional making and uses of the boomerang. Provides information about topics such as boomerangs in fighting, fishing, rituals and trade, decorating boomerangs, and the differences in appearance and usage across Australia. Includes a bibliography. The author has published widely on Aboriginal history and art.

Living in modern society, we have become increasingly disassociated from the earth, from the essence of ourselves, and the need is awakened in us to return to the wilderness--physically and emotionally. We long to feel a sense of connection with our ancient roots. This urge is what has prompted man's fascination with primitive skills: producing objects from natural materials using methods similar to prehistoric cultures. Primitive Technology: A Book of Earth Skills is a sharing of ideas--the philosophies, the history, and the personal stories by the authorities on primitive technology from teh pages of The Bulletin of Primitive Technology. Included are instructions for creating fire and tools of wood, stone, and bone, as well as fiber adhesives, projectiles, art, and music. Practicing these primitive methods will lead the seeker towards a tangible, raw connection with the ancient past, with nature's resources and, ultimately, with the creative forces that constructed the foundation of man's survival on the planet.

HYDRODYNAMIC PROPULSION AND ITS OPTIMIZATION ANALYTIC THEORY Hydrodynamic propulsion has been of major interest ever since craft took to the water. In the course of time, many attempts have been made to invent, develop, or to improve hydrodynamic propulsion devices. Remarkable achievements in this field were made essentially by experienced individuals, who were in need of reliable propulsion units such as paddle wheels, sculling devices, screw propellers, and of course, sails. The problem of minimizing the amount of input energy for a prescribed effective output was first investigated seriously at the beginning of this century. In 1919, BETZ presented a paper on air-screw propellers with minimum consumption of energy which could be applied to ship-screw propellers also. Next, attempts were made to optimize hydrodynamic propulsion units. Ensuing investigations concerned the optimization of the hydrodynamic system: ship-propeller. The first simple theory of ship propulsion which was presented considered more or less only thrust augmentation, wake processing and modification of propeller characteristics when operating behind the ships hull. This theory has been little improved meanwhile and is still useful, particularly with regard to practical ship design and for evaluating results of ship model tests. However, this theory is not adequate for optimization procedures necessary for high-technology propulsion, particularly for ship propellers utilizing propulsion improving devices such as tip end plates or tip fins at the propeller blades, spoilers in front of the propeller, asymmetrical stern etc.

Demonstrating many fundamental concepts of physics and engineering through the working principles of popular science toys is inexpensive, quickly reaching the senses and inspiring a better learning. The systematic way of setting theoretical model equations for the toys provides a remarkable experience in constructing model equations for physical and engineering systems.Given that most science toys are based on the principles of physics, and to cater to the needs of graduate and master-level programme students in physics and engineering, the present book covers more than 40 wide ranging popular toys. For each toy various features are presented including history, construction, working principle, theoretical model, a solved problem and 5-10 exercises.A course on The Physics of Toys can be designed based on the proposed book to be taught as a full course at graduate and master-level and even to students who have never been exposed to physics. Further, the features of the toys covered in this book can be used to illustrate various concepts and principles in different branches of physics and engineering.

Of considerable interest to applied mathematicians as well as sporting enthusiasts is the mathematical theory underlying the many sporting activities documented here, ranging from the high jump to frisbees and soccer to table tennis.

This is a treatment of a number of aspects of the theory of hydrody namic propulsion. It has been written with in mind technical propulsion systems generally based on lift producing profiles. We assume the fluid, which is admitted in conventional hydrody namics, to be incompressible. Further we assume the occurring Reynolds numbers to be sufficiently high such that the inertia forces dominate by far the viscous forces, therefore we take the fluid to be inviscid. Of course it must be realized that viscosity plays an important part in a number of phenomena displayed in real flows, such as flow separation at the nose of a profile and the entrainment of fluid by a ship's hull. Another ap proximation which will be used in general is that the problems are linearized. In other words it is assumed that the induced disturbance velocities are sufficiently small, such that their squares can be neglected with respect to these velocities themselves. Hence it is necessary to evaluate the domain of validity of the results with respect to these two a priori assumptions. Anyhow it seems advisable to have first a good understanding of the linearized non-viscous theory before embarking on complicated theories which describe more or less realistic situations. For elaborations of the theory to realistic situations we will refer to current literature. In low Reynolds number flow, singular external forces and moments are very useful.