For those who fly, a thorough knowledge of the Principles of Flight – also referred to as Aerodynamics - is essential if they are fully to appreciate the flight characteristics of their aircraft, and become safe and proficient pilots. One of the main aims of the Principles of Flight section of the book, therefore, is to provide both student and qualified pilots with study material which will enable them to learn as effectively and enjoyably as possible the scientific principles upon which flight itself depends, and to acquire an understanding of the nature of the physical forces in play when an aeroplane is being manoeuvred. Complementary to the study of the Principles of Flight, in terms of acquiring an understanding of the way an aeroplane flies, is the study of Aeroplane Performance, which is the subject of the second section of this book. The Subject of Aeroplane Performance deals with all the main phases of flight: take-off, climb, cruise, descent and landing. In Aeroplane Performance, it is not only aerodynamic factors but also engine power and thrust considerations, along with atmospheric conditions, which must be borne in mind in order to explain an aeroplane's overall performance. While we have attempted, in this book, to relate the subjects of Principles of Flight and Aeroplane Performance to the practical aspects of piloting, it is a further primary aim of the book to prepare the student pilot for the PPL theoretical knowledge examinations. Appropriate emphasis, therefore, has been given to the pure theory of the two subjects which is demanded by the PPL ground examinations. The depth and scope of the treatment of both subjects are such that this book should also provide a sound introduction to the subjects of Principles of Flight and Aeroplane Performance for those students who are preparing for examinations at professional pilot level.