When the first edition of this book appeared in 1992, it filled a major hole that existed in texts available on current flight dynamics practice. The application of control theory in the 1950s and 1960s was supported by books such as those by Etkin (Dynamics of Flight Stability and Control) and McRuer (Analysis of Nonlinear Control Systems) et al, but by the 1990s, major advances had been made in control theory, computing and simulation and the book by Stevens and Lewis reflected these changes. In subsequent years, many other books have addressed the same area so that flight dynamics is now well served with textbooks. This third edition updates the original material and adds two new chapters on unmanned air vehicles.
The book retains its original chapter subject skeleton with the titles slightly changed and as mentioned has two new chapters added – in total it is some 150 pages longer than the original. This is not, however, a simple graft of new material onto the original book. Many of the chapters have been rewritten so that even where much the same material is covered, it is more detailed and augmented, whilst at the same time maintaining a consistent uniform style across the whole book. As before, each chapter has an introduction explaining the objectives of the chapter and a summary at the end plus a larger selection of problems than the first edition.
The first major change is the notation used in the book. Much the same symbology is used as in the original, but it is augmented by a system of dressings in the form of pre-, post-, super- and subscripts, so as to remove ambiguity from the equations regarding reference frames, axes sets, relative velocities, etc. For example, the symbol
\begin{equation*}
\begin{array}{@{}l@{}}
b \cdot c\\[-2pt]
\hspace*{11pt} {\rm{V}}\\[-9pt]
\hspace*{17pt} A\hbox{/}i
\end{array}
\end{equation*}
represents the components in coordinate system c of the vector derivative taken in frame b of the velocity of point A in frame i. This is much more precise, but it does mean the resulting equations look much more daunting and opaque, and they have to be read carefully.
The first three chapters entitled, ‘The Kinematics and Dynamics of Aircraft Motion’, ‘Modelling the Aircraft’ and ‘Modelling, Design, and Simulation Tools’ are extensively rewritten and are some 54 pages longer than the original chapters. The first chapter provides increased detail regarding the equations required for trans-atmospheric vehicles and has an extended coverage of the kinematic equations for the attitude of a rotating body. The second chapter covers the same material as the original, but it is rearranged and extended with more detail regarding numerical linearisation, trim conditions and the origin and significance of the derivatives. The third chapter is extensively modified with much more emphasis on state space formulation and systems theory.
Chapter 4, ‘Aircraft Dynamics and Classical Control Design’, is slightly reorganised, whilst Chapter 5, ‘Modern Design Techniques’, is unchanged apart from the addition of a section on dynamic inversion. Chapter 6, ‘Robustness and Multivariable Frequency-Domain Techniques’, and Chapter 7, ‘Digital Control’, are unchanged.
The remaining two chapters, Chapter 8, ‘Modelling and Simulation of Miniature Aerial Vehicles’ (41 pages), and Chapter 9, ‘Adaptive Control with Application to Miniature Aerial Vehicles’ (50 pages), are all new. The first part of Chapter 8 concentrates on modelling propeller/rotor forces and moments using a combination of momentum and simple blade element theory and then moves on to rotor flapping models. Simple models of internal combustion engines and electric motors are then discussed. Finally, the ideas are illustrated by three medium-fidelity models, a fixed-wing aircraft, a quadrotor and a helicopter. The final chapter illustrates the application of adaptive control to small air vehicles via dynamic inversion and neural networks. This is an important area for unmanned vehicles because such methods have been distrusted for manned vehicles.
In conclusion, this new edition is a significant update of a popular text but for students the price (£110) may make them look at some of the other books that now occupy this space.
