Excellence in design is one of the principal factors that enable a
developed nation to stay competitive in a global economy. The ability of companies to
add value to a product or manufactured goods is highly regarded throughout the
world. Within this context, aircraft manufacture and operation is regarded as a desirable
commercial activity. Many countries who previously were not involved in aeronautics are
now moving into the business. However, as aircraft are made technically more complex,
involve increasing interdependence between component parts (airframe, engines and
systems), there is an increasing challenge to the industry. The aircraft design team is in
the forefront of this challenge.
Set against this scenario are the conflicts between the
various objectives and requirements for new aircraft projects. The designer is concerned
about increasing performance and quality, meeting production deadlines, promoting
total-life product support, and satisfying customer and infrastructure requirements. Above
all these aspects the designer is expected to meet established safety and environmental
requirements and to anticipate the sociological and political impact of the design.
Balancing all these aspects within an acceptable cost and timescales is what makes
aircraft design such a professionally challenging and ultimately satisfying activity.
One of the educational objectives of an aeronautical
engineering curriculum is to introduce students to the procedures and practices of
aircraft design as a means of illustrating the often conflicting requirements mentioned
above. This textbook describes the initial project stages of civil transport aircraft
design as an example of such practices. Obviously, the methods used have had to be
simplified from industrial practice in order to match the knowledge, ability and
timescales available to students. However, this simplification is made in the level of
specialisation and detail design and not in the fundamental principles. An example of this
approach is the substitution of general purpose spreadsheet methods in place of the
specialist procedural-based mainframe programs commonly used for aircraft analysis in
Apart from a general introduction to aircraft project
design, this book provides an extension to the classical Flight Mechanics
courses. It also bridges the gap between specialist lectures in aerodynamics, propulsion,
structures and systems, and aircraft project coursework. The scope of the book has
purposely been limited to meet the objectives of undergraduate study. In order to
illustrate the basic principles, a simplified approach has had to be made. Where
appropriate, reference is made to other texts for more detailed study. Some prior
knowledge of conventional theories in aerodynamics, propulsion, structures and control is
necessary but where possible the analysis presented in the book can be used without
further study. The terminology and the significance of various parameters is explained at
the point of application and the main notation listed at the end of the book.
The book is arranged in two parts. In Chapters 114
each of the significant influences on aircraft project design is described. This part
starts with a broad introduction to civil air transport, followed by a detailed
description of the design process and a description of aircraft layout procedures. The
next set of chapters are concerned with detailed descriptions of the design methods and an
introduction to the principal aircraft components. The concluding chapters deal with the
parametric methods used to refine the design configuration and a description of the formal
presentation of the baseline design.
The second part of the book (Chapters 1519) includes
an introduction to the use of spreadsheet methods in aircraft design work and four
separate design studies. The studies illustrate the application of such spreadsheet
methods. Each study deals with a separate design topic. The first shows how a simple
design specification is taken through the complete design process. As a contrast the
second study deals with non-passenger aircraft design, considering a transport aircraft.
As both the previous studies deal with conventional configurations the third study shows
how to assess unorthodox layouts. Finally, the last design study shows how you may use the
methods to analyse topics other than pure aircraft technical aspects.
No book alone will provide the key to good design. You can
only achieve this through the acquisition of knowledge, hard methodical work, broad
experience on many different aircraft projects and an open and creative mind. However, we
hope that this book will eliminate some of the minor stumbling blocks that young engineers
find annoying, confusing and time-wasting at the start of their design work.
Wherever possible System International (SI) units have been
used. However, in aeronautics several parameters continue to be used and quoted in non-SI
units (for example altitude is normally in feet). It is therefore necessary to have an
understanding of different systems of units. To allow conversion between different systems
of units a conversion table offers help to both aspiring young designers and older
engineers who struggle to convert their past experience into the new system of units.
Finally, it is impossible to make the book complete. The
contents and data do not cover all the aspects of civil transport design required by every
user. For example, we have not included anything on supersonic aircraft because it is
still uncertain if we can solve the environmental problems (noise and emissions)
associated with high and fast operations. By the same token we have not gone too far on
the inclusion of advanced technologies and materials. Such developments will not affect
the main design process and you could allow for them in future studies by establishing
factors for use in the standard formulae (e.g. mass and drag reduction factors).
However, allowing for these omissions, we have made a
genuine attempt to produce a book that is a starting point for students who want to know
more about the fascinating process of commercial turbofan aircraft design.