Aircraft Flight

For this fourth edition we have updated the text and a number of illustrations. During the twenty years that have elapsed since the first edition was published, there have been few significant outward changes in the shape of aircraft; most developments have been in the areas of electronics, systems and structural materials. Two relatively new classes of aircraft have however emerged: the low orbit space-plane, and unmanned air vehicles. These vehicles are dealt with in this edition. As in the previous edition, we have included an appendix giving the characteristics of three different aerofoils. This information should be particularly useful for project work.

This book is intended to provide a description on the principles of aircraft flight in physical rather than mathematical terms. There are several excellent mathematical texts on the subject, but although many people may be capable of reading them, in practice few will do so unless forced by dire circumstances such as an impending examination and inadequate lecture notes. As a con­sequence, a great deal of aeronautical knowledge appears to be handed on by a kind of oral tradition. As with the great ballads of old, this can lead to some highly dubious versions.

We would of course encourage our readers to progress to the more difficult texts, and we have given suitable references. However it is always easier to read mathematical explanations if you already have a proper understanding of the physics of the problem.

We have included in our account, some of the more important practical aspects of aircraft flight, and we have given examples of recent innovations, descriptions of which are generally only to be found scattered around in assorted technical journals.

Although we do not include any mathematical analysis, we have slipped in one or two simple formulae as a means of defining important terms such as ‘lift coefficient’ and ‘Reynolds number’, which are an essential part of the vocabulary of aeronautics.

In a book of affordable size, we cannot hope to cover every aspect of aircraft flight in detail. We have therefore concentrated on items that we consider to be either important, or interesting. We have also restricted the book to cover the aerodynamics and mechanics of flight, with only the briefest consideration of other important aspects such as structural influences.

We see the book primarily as a general introduction for anyone interested in aircraft or contemplating a career in aeronautics. Students of aeronautical engineering should find it helpful as introductory and background reading. It should also be useful to anyone who has an occupational concern with aero­nautics, either as flight crew, ground staff, or as an employee in the aerospace industry. Finally, we hope that it will be read by anybody who, like us, just finds the whole business of aviation fascinating.

It is assumed that the reader has some school background in elementary physical science, and is at least vaguely familiar with concepts such as energy, and momentum.

Many years ago, someone thought up a convincing, but incorrect explanation of how a wing generates lift; the force required to support the weight of an aircraft in flight. This explanation is, unfortunately, so widely known and believed, that it is probably true to say that most of the world’s aircraft are being flown by people who have a false idea about what is keeping them in the air. Correct descriptions do exist, of course, but they are mostly contained in daunting mathematical texts. Our objective is to give an accurate description of the principles of flight in simple physical terms. In the process of doing so, we will need to demolish some well-established myths.