Aerodynamic theory was not prepared to offer assistance in the early development of the airplane. The scientific community, most qualified for action at the forefront of human endeavor, often turns out in practice to be surprisingly conservative. It is recorded that Lord Rayleigh expressed "not the smallest molecule of faith in aerial navigation, except by balloon." It was not until experiments such as those of Lilienthal and Langley and the successful powered flights of the Wright brothers that correct theories for the aerodynamic action of wings were developed. Following the successful demonstrations of the Wright brothers, aerodynamic theory developed rapidly, primarily in European laboratories. These developments we associate with the names Joukowsky, Kutta, Prandtl and his students, Munk, Betz, and Von Karman. It should not be forgotten that the writings of F. W. Lanchester provide many of the physical insights that were elaborated in these mathematical theories. Throughout World War I, these developments in aerodynamic theory remained virtually unknown in the U.S. However, in the early 1920's, the U.S. National Advisory Committee for Aeronautics undertook to translate or otherwise make available important works on aerodynamic theory in the form of NACA Technical Reports, Notes, and Memoranda, and to encourage similar effort in its own laboratory. At the present time, many of these old NACA documents are no longer readily available and it seems worthwhile to collect the most important early works under the title "Classical Aerodynamics." In most cases, the theories are explained in the author's own words and often with a degree of clarity unequalled in later interpretations. R. T. Jones Senior Staff Scientist NASA-Ames Research Center June 18, 1979 CONTENTS Preface Applications of Modern Hydrodynamics to Aeronautics L. Prandtl The Mechanism of Fluid Resistance Th. v. Karman and H. Rubach Pressure Distribution on Joukowski Wings Otto Blumenthal Graphic Construction of Joukowski Wings E. Trefftz The Minimum Induced Drag of Aerofoils Max M. Mun K The Aerodynamic Forces on Airship Hulls Max M. Munk Elements of the Wing Section Theory and of the Wing Theory Max M. Munk Remarks on the Pressure Distribution over the Surface of an Ellipsoid, Moving Translationally Through a Perfect Fluid Max M. Munk The Inertia Coefficients of an Airship in a Frictionless Fluid H. Bateman Flow and Drag Formulas for Simple Quadrics A. F. Zahm Flow and Force Equations for a Body Revolving In a Fluid A. F. Zahm Behavior of Vortex Systems A. Betz General Potential Theory of Arbitrary Wing Sections T. Theodorsen and I. E. Garrick General Theory of Aerodynamic Instability and the Mechanism of Flutter Theodore Theodorsen