Book Review for The Aeronautical Journal

Title:-                        Flight Dynamics

Author:-                   Robert F. Stengel

Publisher:-                Princeton University Press

Publication date:-    2004

ISBN:-                      0-691-11407-2

Retail Price:-             $99.50 (£65.00)

Reviewer:-                M.V.Cook, School of Engineering, Cranfield University.

 

The eminence of Professor Robert Stengel will be well known to most engineers, scientists and academics working in the field of flight dynamics. His universally acknowledged position as a leading academic in the field derives from his “real world” experience which includes involvement in the design of the Apollo Lunar Module and the direction of many flight experiments in the modified Navion light aircraft at Princeton. Over a period of many years the results of his research have been published in countless papers. Since he is an undisputed authority in the field of flight dynamics it came as no surprise to learn that he has published a new book on the subject and an opportunity to review this text was eagerly awaited.

 

First impressions were that this is a substantial book (845 pages) and that it is extremely well researched, having a very large number of references and a useful bibliography of NASA reports related to aircraft configuration aerodynamics. The content of the book is a little unusual in that it really is totally focused on the topics we understand to comprise modern Flight Dynamics, the author having resisted the temptation to stray into the closely related field of flight control. However, flight control system topics are included appropriately where it is relevant to do so. It is pleasing to see that the subject treatment is securely founded on aerodynamics and flight physics, and that subsequent topic development makes extensive use of the mathematics and tools of modern systems analysis. This, of course, is entirely consistent with the computer age in which we now live and work and it helps to make the material readily accessible.

 

The style of the book also differs a little from the norm. It reflects the unmistakable enthusiasm of the author for the subject, his considerable application experience and his ability to make the most complex topic easy to assimilate – a skill no doubt refined over many years of teaching students. His approach is to take each topic, to reduce to its most basic foundations and then to develop it step by step until the desired objective is reached. This means, for example, that the reader is taken through a mathematical development from its most elementary starting point. In comparison, most authors of similar texts omit the most basic steps on the basis that it is assumed prior knowledge. The dangers of this approach in a teaching context are well known. Consequently, it seems at first sight that some of the material in the book is pedantically comprehensive. However, this opinion is short lived when it is appreciated just how accessible the material becomes as a result of this approach. The style must therefore greatly enhance the book as a learning resource for students and it also makes it an especially valuable reference for those already familiar with the subject area. This reviewer found the book so useful in this respect that the review process was temporarily overlooked!

 

In spite of its considerable volume, the book has only seven main chapters, which reflects the thorough and comprehensive treatment of the material. The introductory material reviews a variety of modern aircraft “shapes” and comments very briefly on their principal characteristics in context. No doubt with the student in mind, the introduction concludes with a Matlab example showing how the flight mechanics of a simple paper aeroplane can be modelled and evaluated. The second chapter is called Exploring the flight envelope, and serves to introduce all the foundation flight mechanics. This covers atmosphere physics, axes systems, kinematics, aerodynamics, powerplants and performance. The objective here is to assemble the basic mathematical models on which all flight dynamics depends. The third chapter, Dynamics of aircraft motion, builds an extremely complete mathematical model of the aircraft with reference to both linear and non-linear solutions. A substantial part of this chapter includes an in-depth discussion of the aerodynamic contributions to the equations of motion. Chapter four deals with Methods of analysis and design, and unusually it deals with both the familiar and the less familiar. Topics include linearization, solution of linear differential equations, stability, time and frequency domain analysis, parameter uncertainty, aeroelasticity and flying qualities and flight control. Chapters five and six deal with Longitudinal motions and Lateral-directional motions respectively. The approach is similar in both chapters and most of the topics are familiar. However, the depth of the analytical discussion is considerably greater than is usual in books on the subject and the detail affords a powerful insight into aircraft dynamics. Chapter seven deals with Coupled longitudinal and lateral-directional motions. Topics include small amplitude motions, inertial coupling, “systems” exhibiting dynamic bifurcation and some of the most recent advances relating to flight at very high angles of attack.

 

Clearly, the book has been written with the student market in mind as it includes many worked examples to illustrate application of the material. Further, much of the example material is structured around a suite of Matlab programs which are available from the author and I am sure that the interest in this material will extend well beyond the student market. Summaries of the software tools and tutorial example aircraft models are given in the appendices. However, the reader can download the programs from the authors’ web site - http://www.pupress.princeton.edu/stengel.

 

This is a terrific book which should appeal to students and practitioners alike. It is most comprehensive, thorough in its detail and the style of writing makes the subject easily accessible to all. Students and teachers will find in it a resource that is complete and compatible with the requirements of the industry and research organisations. Practising engineers and researchers will find the book an invaluable reference, especially as it is comprehensive and starts from first principles which makes it easier to deal with unconventional configurations. All that is required of the reader is a reasonable graduate level ability in engineering mathematics, but such is the thoroughness of the treatment that much of the mathematics is explained as well. I recommend this book without hesitation to those engaged in, or aspiring to become engaged in, flight dynamics, flight test, flight control and related flight sciences. Priced at £65 it represents very good value for money, and for that it is hardbound as well!