Aerodynamic Theory

Part of the Princeton Aeronautical Paperback series designed to bring to students and research engineers outstanding portions of the twelve-volume High Speed Aerodynamics and Jet Propulsion series. These books have been prepared by direct reproduction of the text from the original series and no attempt has been made to provide introductory material or to eliminate cross reference to other portions of the original volumes. Originally published in 1960. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

An excellent introduction to inviscid airflow using potential theory, this book is a classic in its field. Complete reprint of the revised 1966 edition, which brings the subject up to date.

Why do aircraft fly? How do their wings support them? In the early years of aviation, there was an intense dispute between British and German experts over the question of why and how an aircraft wing provides lift. The British, under the leadership of the great Cambridge mathematical physicist Lord Rayleigh, produced highly elaborate investigations of the nature of discontinuous flow, while the Germans, following Ludwig Prandtl in Göttingen, relied on the tradition called “technical mechanics” to explain the flow of air around a wing. Much of the basis of modern aerodynamics emerged from this remarkable episode, yet it has never been subject to a detailed historical and sociological analysis. In The Enigma of the Aerofoil, David Bloor probes a neglected aspect of this important period in the history of aviation. Bloor draws upon papers by the participants—their restricted technical reports, meeting minutes, and personal correspondence, much of which has never before been published—and reveals the impact that the divergent mathematical traditions of Cambridge and Göttingen had on this great debate. Bloor also addresses why the British, even after discovering the failings of their own theory, remained resistant to the German circulation theory for more than a decade. The result is essential reading for anyone studying the history, philosophy, or sociology of science or technology—and for all those intrigued by flight.

In this second edition a new chapter has been added covering the buffeting theory in a finite element format. The motivation for this has been that a finite element format is becoming more and more dominant in all areas of structural mechanics. It is streamlined for computer programming, and it facilitates the use of general purpose routines that are applicable in several types of structural engineering problems. In this book the finite element formulation of the problem of dynamic response calculations follows the general principle of virtual work, a general principle which may be found in many other text books. While the buffeting wind load itself has with no trouble been included in a finite element format, the main challenge has been to obtain a consistent formulation that includes all the relevant motion induced forces. This has been important, because, while many structures (e.g. long-span suspension bridges) may suffer greatly and become unstable at high wind velocities, the same structures may also benefit from these effects at the design wind velocity. It is well known that motion induced forces will change the stiffness and damping properties of the combined structure and flow system. If calculations are performed for a suitably close set of increasing mean wind velocities and the changing mechanical properties (stiffness and damping) are updated from one velocity to the next, then the response of the system may be followed up to wind velocities close to the stability limit, i.e. up to response values that are perceived as unduly large. Finite element calculations may be performed in time domain, in frequency domain or converted into a modal format. All these options have been included. Pursuing a time domain solution strategy requires the use of the so-called indicial functions. The theory behind such a formulation is also covered, and the determination of these functions from aerodynamic derivatives has been included in a separate appendix.

This book provides an introduction to ground vehicle aerodynamics and methodically guides the reader through the various aspects of the subject. Those needing specific information or a refresher can easily jump to the material of interest. There is a particular emphasis on various vehicle types (passenger cars, trucks, trains, motorcycles, race cars, etc.). However, the book is focused on cars and trucks, which are the most common vehicles in the speed range in which the study of ground vehicle aerodynamics is beneficial. Readers will gain a fundamental understanding of the topic, which will help them design vehicles that have improved aerodynamics; this will lead to better fuel efficiency, improved performance, and increased passenger comfort. The author’s basic approach to the presentation of the material is complemented with review questions, application questions, exercises, and suggested projects at the end of most of the chapters, which helps the reader apply the information presented, either in the classroom or for self-study. Aside from offering a solid understanding of ground vehicle aerodynamics, the book also offers more thorough study of several key topics. One such topic is car-truck interaction, when one vehicle (usually the smaller one) is overtaking the other. There is a direct and instant benefit in terms of safety on the highway from understanding the forces at play when one vehicle passes the other in the same direction and sense. Chapters examine: • Drag • Noise and vehicle soiling • Wind tunnels and road/track testing • Numerical methods • Vehicle stability and control • Vehicle sectional design • Large vehicles: trucks, trailers, buses, trains • Severe service and off-road vehicles • Race cars and convertibles • Motorcycles • Concept vehicles