The Aerodynamic Design of Aircraft

596 Pages·2012·31.68 MB·English

by  Dietrich Küchemann

AIAA EDUCATION SERIES
Editor-in-Chief
Joseph A. Schetz
Virginia Polytechnic Institute and State University
Editorial Board
Joe0 Luiz F. Azevedo Brian Landrum
Comando-Geral De Tecnologia University of Alabama in Huntsville
Aeroespacial
Michael Mohaghegh
Marty Bradley The Boeing Company
The Boeing Company
Conrad F. Newberry
James R. DeBonis
NASA Glenn Research Center Brett Newman
Old Dominion University
Kajal K. Gupta
NASA Dryden Flight Research Center Mark A. Price
Queen’s University Belfast
Rickard B. Heslehurst
University of New South Wales Hanspeter Schaub
University of Colorado
Rakesh K. Kapania
Virginia Polytechnic Institute and State David M. Van Wie
University Johns Hopkins University
The Aerodynamic Design
of Aircraft
Dietrich Kuchemann
AlAA EDUCATION SERIES
Joseph A. Schetz, Editor-in-Chief
Virginia Polytechnic Institute and State University
Blacksburg, Virginia
Published by the
American Institute of Aeronautics and Astronautics, Inc.
1801 Alexander Bell Drive, Reston, Virginia 20191-4M
American Institute of Aeronautics and Astronautics, Inc., Reston, Virginia
1 2 3 4 5
Library of Congress Cataloging-in-Publication Data
Record on file
Copyright 0 2012 by Dietmar Kuchemann. All rights reserved. Published by the
American Institute of Aeronautics and Astronautics, with permission. Printed in the
United States of America. No part of this publication may be reproduced, distributed,
or transmitted, in any form or by any means, or stored in a database or retrieval system,
without the prior written permission of the publisher.
Data and information appearing in this book are for informational purposes only. AIAA
is not responsible for any injury or damage resulting from use or reliance, nor does
AIAA warrant that use or reliance will be free from privately owned rights.
ISBN 978-1-60086-922-8
CONTENTS
Foreword xi
Preface xv
Chapter 1 Prolegomena 1
1.1 Some introductory observations 1
1.2 An overall technical assessment 4
1.3 The motivation of aviation 12
1.4 The design problem 19
Chapter 2 The Treatment of Airflows 23
2.1 Models to describe the air and some of its properties 23
2.2 Some methods to describe inviscid flows 26
2.3 Some models to describe the compressibility of the air 33
2.4 Viscous interactions-flow separations 36
2.5 Flows suitable for aircraft applications 52
Chapter 3 Means for Generating Lift and Propulsive Forces 56
3.1 Overall lift and associated drag forces 56
3.2 Wings with near-planar vortex wakes 58
3.3 Slender wings with non-planar vortex wakes 69
3.4 Lifting bodies with shockwaves 71
3.5 Overall thrust forces 77
3.6 Propulsion flow cycles 78
3.7 Elements of propulsion engines 88
Chapter 4 Properties of Classical and Swept Aircraft 103
4.1 A family of aircraft according to Cayley’s concept 103
4.2 An extension to swept-winged aircraft 111
4.3 Classical wing theory and some extensions 121
4.4 Threedimensional sweep effects 135
4.5 Viscosity effects 151
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viii The Aerodynamic Design of Aircraft
4.6 Separation effects 161
4.7 High-lift effects 168
4.8 Swept wings in transonic flow 184
4.9 Swept wings in supersonic flow 212
Chapter 5 The Design of Classical and Swept Aircraft 221
5.1 Some design aims for swept wings 221
5.2 Aerofoil section design 225
5.3 Threedimensional wings 241
5.4 Some special designs 252
5.5 The fuselage 257
5.6 Wing-fuselage interference 266
5.7 Interfering wings and ground effects 289
5.8 Some effects of non-uniform flows 305
5.9 Some propulsion problems 313
5.10 Some problems of complete aircraft 328
Chapter 6 Properties and Design of Slender Aircraft
for Supersonic Flight 338
6.1 The evolution of the design concept 338
6.2 Families of slender aircraft 342
6.3 Properties of vortex flows over slender wings 35 1
6.4 Theories for separated flows 374
6.5 General properties of wings at low speeds 387
6.6 The design of warped wings with attached flow 405
6.7 Non-lifting wings at supersonic speeds 412
6.8 Lifting wings at supersonic speeds 42 1
6.9 Some problems of complete aircraft 432
Chapter 7 Slender Aircraft for Flight at Subsonic Speeds
Over Short Ranges 439
7.1 Gates’ concept of an aerobus 439
7.2 Performance considerations 441
7.3 Design considerations 44f3
Chapter 8 Waverider Aircraft 448
8.1 The waverider concept and its possible applications 448
8.2 Design of lifting bodies from known flowfields 452
8.3 Off-design characteristics 465
8.4 Effects of viscosity 477
Contents ix
8.5 Heat addition to airstreams 496
8.6 Propulsive lifting bodies 502
Chapter 9 Conclusions and Outlook 511
References 515
Index 557
Supporting Materials 565
FOREWORD
When Dietrich Kuchemann’s The Aerodynamic Design of Aircraft was
published posthumously in 1978, it was a unique and forward thinking
text comprising the philosophy and life’s work of a unique and visionary
intellect. Dietrich Kuchemann studied under Ludwig Prandtl at the Univer-
sity of Gottingen from 1930 until receiving his doctorate in 1936. He was a
research scientist at the Aerodynamische Versuchs Anstalt Gottingen for
ten years before coming to work at the Royal Aircraft Establishment
Farnborough. He would continue working at the RAE in a variety of scien-
tific and leadership roles until his death in 1976. For the last four years of his
life, he taught a course at Imperial College London upon which this book is
based.
Dietrich Kuchemann was a preeminent aerodynamicist of his era. His
early work with Dr. Johanna Weber, his lifelong scientific collaborator,
helped usher in the jet age and resulted in the publication of Aerodynamics
of Propulsion in 1953. His conception of and work on slender-wing super-
sonic aircraft strongly influenced the development of the Concorde. In 1962
Kuchemann was awarded the Royal Aeronautical Society‘s Silver Medal and
in 1963 he was elected a Fellow of the Royal Society. He was appointed a
Commander of the British Empire in 19M. In 1970 he received the Ludwig
Prandtl Ring.
In addition to his many technical contributions, Kuchemann was a
tireless advocate for the aerospace community. He was the founder and
principal editor of the journal Progress in Aeronautical Sciences (now Pro-
gress in Aerospace Sciences) from 1961 until his death. He served on the
AGARD Fluid Dynamics Panel from 1965, including serving as its chair
from 1973 - 1975.
The Aerodynamic Design of Aircraft is quite unlike most engineering
texts. Engineering texts are typically focused on a set of tools-the rigorous
derivation and presentation of analysis techniques sufficient to span a
discipline. Kuchemann’s approach is to focus on the problem and its
solution-what kind of flow is best for a given class of aircraft and how to
achieve it. In this approach, Kuchemann fully embraces the true inverse
nature of design; rather than answer “what flow given the shape,” he strives
to answer “what flow given the purpose” and then “what shape given
the flow.”
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xii The Aerodynamic Design of Aircraft
Kuchemann establishes three classes of aircraft based on the character
of flow involved. Each class is suitable for a distinct cruise speed
regime: classical and swept aircraft for subsonic and transonic cruise,
slender-wing aircraft for supersonic cruise, and wave-rider aircraft for
hypersonic cruise. The desired flow for each kind of aircraft has distinct
structure: classical and swept aircraft with streamlined and attached flow
separating from the trailing edge of airfoils, slender-wing aircraft with vor-
tices attached to sharp leading edges, and wave-rider aircraft with a strong
shock attached to the leading edges of the underside of the wing.
In addition to the structure of each flow, Kuchemann establishes the
need for each flow to be “healthy.”A healthy flow exhibits the desired struc-
ture and is stable and controllable not only at the design point, but also at
off-design operating conditions. The forces and moments on the aircraft
must change gradually and continuously throughout the flight envelope.
My own experience with this book is one that almost didn’t happen. For
years, I knew this book, then long out-of-print, only by reputation; although
highly regarded and oft cited, I had never managed to find a copy of my
own. My desire for this text had led me to request an automated notification
from an online auction site. That request went unfulfilled for more than a
year. I remarked on this situation before a technical meeting of aircraft
design practitioners, researchers, and educators in the spring of 2009 only
to find out that another member of the group had requested the same noti-
fication from the same site. We were all quite amused that if a copy were to
become available, two friends would unknowingly become embroiled in
a fierce bidding war. As luck would have it, just a few days after that
meeting, I was notified of an available copy and was able to secure purchase
before my friend.
Upon its arrival, I found that this book exceeded its reputation as a
unique treatment of aerodynamic design. I became determined that The
Aerodynamic Design of Aircraft must be reprinted and made available
again to the aerospace community. Later that year, I received enthusiastic
support for this project from the membership and leadership of the
AIAA Aircraft Design Technical Committee. With their backing, I
approached the publishing staff of the AIAA about pursuing this project.
Although this project has been long in coming, its completion stands as a
tribute to the dedication of Dietrich Kuchemann’s family and the editors
of the AIAA Education Series.
The Aerodynamic Design ofAircraft is as relevant and as forward looking
today as it was in 1978. The swept wing aircraft, in becoming the mainstay
of the aerospace industry, has achieved a high degree of sophistication, but
much of the nuance contained in this text, required to continue advancing
these designs, is lost outside a few experienced practitioners in industry.
Since the Concorde, there has been no second generation of supersonic
Fore word xiii
transport aircraft. Acceptable sonic boom is the primary challenge facing
developers of supersonic business jets, but these aircraft will also have to
balance cruise efficiency and must still achieve healthy flow. The past few
years have seen the successful development and test of several scramjet
engine and hypersonic vehicle technology programs. These programs
build the case for the development of a generation of hypersonic wave-
rider vehicles as foreseen by this text.
Kuchemann understands, explains, and advocates the integration of
aerodynamic and propulsive roles of air vehicles in a way now considered
essential for the success of the next generation of vehicles of all classes.
Recent years have seen dramatic progress in the use of computation for
aerodynamics. Computational fluid dynamics provides an incredibly
powerful tool for sophisticated aerodynamic analysis. Aerodynamic shape
optimization techniques are poised to provide an equally powerful tool
for sophisticated aerodynamic design. Despite the rigor and power of
these techniques, they fail to provide the guidance of this text as to what
flow or shape is desired. Kuchemann’s call for healthy flow having the
same characteristics off- and on-design rings true today. The physical
insight and intuition conveyed by this text are timeless.
With the republication of this text, Dietrich Kuchemann’s influence will
extend to the next generation of the aerospace industry and the vehicles it
will produce. I know he would be proud that so many, including my friend,
will finally have access to this work.
Rob McDonald
San Luis Obispo, CA
June 2012