AUTHOR’S PREFACE

Between the years of 1945 and 1950, the author consolidated his aerodynamic experience (since 1930) as a researcher, wind-tunnel experimenter, designer and as a pilot (in organizations such as Junkers and Messerschmitt) by writing “Aerodynamic Drag”. After augmenting his knowledge through the numerous publications pouring out after that time, he then wrote and published “Fluid-Dynamic Drag” (1958), second edition 1965. On the basis of this book he was asked by the U. S. Navy’s Office of Naval Research, whether he could and would write a text on “lift”. Thus encouraged and aided by Contract Nonr-3196(00), the author set out writing “Fluid-Dynamic Lift”.

The number of available publications and technical reports dealing with aerodynamic lift, may now be between 10 and 20,000. It soon became obvious that not all of these could be evaluated. To reduce the amount of effort and complexity, the author restricted the subject to subsonic speeds. Even then, it was found impossible to study all of the remaining, say 10,000 sources of information. However, not all of the published information is worth reading. Possibly 50% of it is obsolete, unnecessary, repetitious, and some of it is misleading. If the author did not use all of the useful results available, there is a point of view given as advice by the late Hugo Junkers to his engineers. He told them, when studying and developing something new, not to look up what others had done and found in the same field. New ideas, aspects and conclusions may thus be reached, without interference by premature and/or erroneous judgements by others. The best way of using existing information seems to be to take indisputable facts, and to explain and accept them in spite of conclusions and theoretical indications to the contrary. To be sure, it is the author’s intent to find the “truth” about the many aspects of fluid-dynamic lift. However, as a French research professor (Ourisson, Ecole Normale Superieure in Paris) has said, “the search for truth is influenced by one’s idea of what the truth must be”. In this respect, the author never accepts what theory says it “must” be. Emphasis is placed upon the deviations from theoretical predictions, although any theoretical analysis is gratefully used as soon as it consistently agrees with experimental results. In particular, theory can thus be used to extrapolate available statistical data.

After completion of* this text, the author wishes to thank and/or to acknowledge the help of those, without whom the book could not have been written; among them Cdr. H. B. Keller and Mr. Ralph C. Cooper of the Office of Naval Research, Mr. G. L. Desmond at the Bureau of Weapons, the Office of Scientific Research of the U. S. Air Force, the NACA or NASA (where most of the technical reports came from) and the librarians of the American Institute of Aeronautics and Astronautices.

S. Hardy F. Hoerner

New York City January 1967

THE AUTHOR studied mechanical engineering at the Institute of Technology in Miin- chen (Dipl. Ing.), he earned a degree as Dr.-Ing. in aerodynamics at the Institute of Technology in Braunschweig, and he obtained a degree as Dr.-Ing. habil. from the TH Berlin. He served at one time as research assistant at the Deutsche Versuchsanstalt fur Luftfahrt (DVL, near Berlin), as aerodynamicist in the Fieseler Corporation (working on the first STOL airplane, the "Stork”) and later for a time as head of design aerody­namics in the Junkers A. G. He was then research aerodynamicist at the Messerschmitt A. G. After World War II, the author was invited to come to the United States, where he worked in aerodynamics at Wright Field, Ohio. For some years he has been acting as specialist for aerodynamics and hydrodynamics in the field of naval architecture at Gibbs & Cox, Inc., New York City.

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