The Enigma of the Aerofoil: Rival Theories in Aerodynamics, 1909-1930

562 Pages·2011·2.59 MB·English

by  David Bloor

The Enigma of the Aerofoil
frontispiece. Before and after the first meeting of the Advisory Committee for Aeronautics. The
meeting took place on May 12, 1909, with Rayleigh assuming the chair at 2:30 p.m. The caption identifies
Glazebrook and Rayleigh, but who were the other two gentlemen? I tentatively identify the man next to
Rayleigh as H. R. A. Mallock and Glazebrook’s companion as F. J. Selby. From the Daily Graphic, May 13,
1909. (By permission of the Trustees of the National Library of Scotland)
The Enigma of
the Aerofoil
Rival Theories in Aerodynamics, 1909–1930
david bloor
The University of Chicago Press
Chicago and London
David Bloor is professor emeritus in the Science Studies Unit at the University of
Edinburgh. He is the author of Knowledge and Social Imagery and coauthor of Scientific
Knowledge: A Sociological Analysis, both published by the University of Chicago Press.
The University of Chicago Press, Chicago 60637
The University of Chicago Press, Ltd., London
© 2011 by The University of Chicago
All rights reserved. Published 2011.
Printed in the United States of America
20 19 18 17 16 15 14 13 12 11 1 2 3 4 5
isbn-13: 978-0-226-06094-1 (cloth)
isbn-13: 978-0-226-06095-8 (paper)
isbn-10: 0-226-06094-2 (cloth)
isbn-10: 0-226-06095-0 (paper)
Library of Congress Cataloging-in-Publication Data
Bloor, David.
The enigma of the aerofoil : rival theories in aerodynamics, 1909–1930 / David Bloor.
p. cm.
Includes bibliographical references and index.
isbn-13: 978-0-226-06094-1 (cloth : alk. paper)
isbn-10: 0-226-06094-2 (cloth : alk. paper)
isbn-13: 978-0-226-06095-8 (pbk. : alk. paper)
isbn-10: 0-226-06095-0 (pbk. : alk. paper) 1. Aerodynamics—History.
2. Prandtl, Ludwig, 1875-1953. I. Title.
tl570.b566 2011
629.132′3—dc22
2011013059
¥ This paper meets the requirements of ansi/niso z39.48–1992 (Permanence of
Paper).
Contents
List of Illustrations vii
Acknowledgments xi
Introduction: The Question to Be Answered 1
1 Mathematicians versus Practical Men:
The Founding of the Advisory Committee for Aeronautics 9
2 The Air as an Ideal Fluid:
Classical Hydrodynamics and the Foundations of Aerodynamics 40
3 Early British Work on Lift and Drag:
Rayleigh Flow versus the Aerodynamics of Intuition 79
4 Lanchester’s Cyclic Theory of Lift and Its Early Reception 111
5 Two Traditions:
Mathematical Physics and Technical Mechanics 160
6 Technische Mechanik in Action:
Kutta’s Arc and the Joukowsky Wing 200
7 The Finite Wing:
Ludwig Prandtl and the Göttingen School 247
8 “We Have Nothing to Learn from the Hun”:
Realization Dawns 304
9 The Laws of Prandtl and the Laws of Nature 340
10 Pessimism, Positivism, and Relativism:
Aerodynamic Knowledge in Context 399
Notes 447
Bibliography 497
Index 535

Illustrations
frontispiece Before and after the first meeting of the Advisory Committee
1.1 Richard Burdon Haldane (1856–1928) 11
1.2 Advisory Committee for Aeronautics and its institutional context 15
1.3 Richard Tetley Glazebrook (1854–1935) 16
1.4 The controversial BE2 developed by the Royal Aircraft Factory 24
1.5 C. G. Grey, editor of the Aeroplane 26
1.6 George Hartley Bryan (1864–1928) 31
1.7 Grahame-White type 10 aero charabanc, 1912 38
2.1 Small control volume used to arrive at the equation of continuity 45
2.2 Fluid element 47
2.3 Pitot tube, static tube, and Pitot-static probe 54
2.4 Streamlines of flow past a circular cylinder 60
2.5 Ideal fluid flowing around a barrier 61
2.6 Continuous flow around an inclined plate 68
2.7 Discontinuous flow around a barrier 71
3.1 Discontinuous or “Rayleigh” flow around an inclined plate 80
3.2 John William Strutt, Lord Rayleigh (1842–1919) 81
3.3 Sir Alfred George Greenhill (1847–1927) 84
3.4 Greenhill’s figure 13 87
3.5 Greenhill’s figure 14 88
3.6 The relation between the lift and the angle of incidence of a wing 92
4.1 A steady wind and a vortex 114
viii illustrations
4.2 A flow combining a steady wind and a vortex, and vector addition and
the parallelogram of velocities 115
4.3 Flow resulting from a uniform free stream and a vortex 116
4.4 Circulation is contour-independent for an idealized vortex flow 121
4.5 The flow along a contour 121
4.6 The circulation around an aerofoil 122
4.7 Frederick William Lanchester (1868–1946) 125
4.8 Lanchester’s pictures of trailing vortices 128
4.9 Lanchester’s account of a spinning ball 132
4.10 Leonard Bairstow (1880–1963) 151
5.1 Horace Lamb (1849–1934) 168
5.2 A single source in a uniform flow of ideal fluid 174
5.3 A system of sources and sinks to simulate the flow around an airship 175
5.4 Richard von Mises (1883–1953) 180
5.5 August Föppl (1854–1924) 189
6.1 Martin Wilhelm Kutta (1867–1941) 201
6.2 Muriel Barker’s notes on Kutta’s 1910 paper 210
6.3 A paradox? 213
6.4 The “paradox” resolved 214
6.5 Kutta’s analysis of leading-edge flow 216
6.6 Joukowsky’s geometrical construction of a winglike profile 226
6.7 Joukowsky’s construction of a strut or rudder 227
6.8 Blumenthal’s unifying principle 232
6.9 Blumenthal’s predicted pressure distributions 233
6.10 Ludwig Prandtl and Albert Betz 234
6.11 Betz’s pressure graphs for a Joukowsky aerofoil 236
6.12 Betz abandons the Kutta condition 237
6.13 Betz’s revised pressure graphs after modification of the Kutta condition 239
6.14 Kármán-Trefftz profile 241
6.15 A von Mises profile with a zero pitching moment 243
7.1 Ludwig Prandtl (1875–1953) 249
7.2 Separation of the boundary layer 249
7.3 Felix Klein (1849–1925) 254
7.4 Theodore von Kármán (1881–1963) 259
illustrations ix
7.5 Trailing vortices from the wingtips 262
7.6 The trailing vortices induce a downward flow behind the wing; tilt in the air-
flow produces an “induced drag” 264
7.7 The Biot-Savart law 265
7.8 The induced velocity due to a finite vortex segment 266
7.9 Application of the Biot-Savart law to the horseshoe vortex 267
7.10 Föppl’s model for testing Prandtl’s prediction of downwash 270
7.11 Stepwise complication of the simple horseshoe model 277
7.12 Geometry of an ellipse, and an elliptical distribution of lift and circulation 282
7.13 Two polar curves relating induced drag and lift 288
7.14 Lanchester’s trailing vortices divide the space around a wing 293
7.15 The rolling up of the vortex sheet behind a finite wing 295
7.16 Einstein’s profile 95 stands out because of its unusual shape 299
7.17 Flow through a variable cross section 301
7.18 Flow of an ideal fluid with circulation around an arc 302
8.1 Foreign publications available to members of the Advisory Committee 307
8.2 The Chudleigh set 309
8.3 Hermann Glauert (1892–1934) 314
9.1 G. I. Taylor (1886–1975) 344
9.2 G. I. Taylor’s counterexample to Bryant and Williams 347
9.3 Taylor’s reanalysis of Rayleigh flow 350
9.4 The contours and circulation in Bryant and Williams’s experiment 352
9.5 Fage and Simmons’s experiment to test the theory of the finite wing 358
9.6 Apparatus used by Fage and Simmons 359
9.7 Lines of equal vorticity behind a finite wing 361
9.8 Circulation created by the bound vortices 363
9.9 The streamlines of a trailing vortex 364
9.10 Richard Vynne Southwell (1888–1970) 369
9.11 The initial moment in the creation of a vortex 377
9.12 The creation of circulation around a wing 378
9.13 Stationary fluid around a strut 384
9.14 Strut in motion with confluence at rear edge 385
9.15 Klein’s coffee-spoon experiment 387
9.16 Harold Jeffreys (1891–1989) 388