Aerodynamics of the helicopter

BOOK REVIBWS AERODYNAMICS OF Trm HELICOPTER, by Alfred Gessow and Garry C. Myers, Jr. 343 pages, illustrations, 14 X 22 cm. New York, The Macmillan Co., 1952. Price, $6.00. This reviewer continues to be delighted by the excellent texts on the various specialized subjects in aeronautical engineering theory and design to appear on the market in recent years. The relatively new and rapidly expanding field of helicopter aerodynamics and design has created many gaps in the essential background of student and graduate aeronautical engineers and the busy practicing aeronautical engineers in allied fields who are merely conversant with the myriad aspects of rotary wing fundamentals. For the most part, the information presented screens and integrates a vast a m o u n t of theoretical and practical information on the subject in heretofore widely scattered, and in many cases unavailable, sources. As such, this book bridges m a n y of these gaps in a concise and progressive manner; this is 11o simple task. Since the authors' wealth of experience in the helicopter field was gained in the Flight Research Division of the Langley Labs. of the NACA, they were well qualified to assemble and organize the past and most recent rotary wing material into such a complete and practical guide in the theoretical and physical terms most useful to the student and engineer alike. An extensive bibliography of all NACA papers on the subject, as well as papers from other sources, is given in the appendix. In presenting the material, the authors have succeeded in illustrating physical concepts for those phenomena associated with rotating wings. Lengthy mathematical formulae and derivations are rightly avoided except where they are of prime significance, thus sidestepping the usual "padding" and consequent loss of meaningfulness too often employed in the past by many authors of technical publications of this type. The book is divided into twelve major chapters. The initial chapters deal with the development of rotary wing aircraft, an introduction to the helicopter and an introduction to hovering theory. Next are chapters on hovering and vertical-flight analyses and those factors affecting the related performance, followed by a presentation of autorotation in vertical descent. The succeeding chapters are concerned with physical concepts of blade motion and rotor control, the aerodynamics of forward flight, forward-flight performance, the prediction and effects of rotor blade stall, an introduction to helicopter stability, and finally all introduction to helicopter vibration problems. SAMUEL M. BERKOWITZ THE CHEMISTRY OF SYNTHETIC DYES, Vol. I, by K. Venkataraman. 704 pages, tables, diagrams, 16 X 24 cm. New York, Academic Press, Inc., 1952. Price, $14.50. This book extensively surveys the developments in the dyestuffs industry, the chemical processes involved in the manufacture of synthetic dyes, the methods of application, and the theories of color. Despite the rather broad scope of the book, it is presented in a readable style. The building blocks on which the synthetic dye industry is based are listed, and their sources and manufacture are described in detail. Standard procedures for testing the purity of these primary compounds are included. The unit processes of organic synthesis such as sulfonation, chlorination, nitration and reduction, alkali fusion, etc. are discussed in some detail as they relate to the manufacture of dye intermediates. In a lucid, organized manner the author traces the synthesis of most of the common and uncommon intermediates. Several chapters are devoted to the theory and measurement of color in which there is a discussion of the relationship between chemical structure and the colors emitted. He describes with little comment the various theories which have been presented to correlate the absorption spectrum of an organic compound with its chemical constitution. However, there is an extensive discussion of the theory of color in which he presents his own views. The latter half of the book describes the chemistry, manufacture, and application of the dyes used in the textile industry. Detailed processes are not included, and are certainly beyond 613