Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/12

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PREFACE.

considered a vital question from a National point of view is beyond dispute; under the conditions of the near future the command of the air must become at least as essential to the safety of the Empire as will be our continued supremacy on the high seas.

The present volume deals exclusively with the Aerodynamics of Flight; the arrangement of this section is as follows:—

Chapters I.. II, and III, are devoted to the preliminary exposition of the underlying principles of fluid dynamics, examined from different points of view. Chapter I, is of an introductory character, and includes a discussion as to the nature of fluid resistance, the theory of the Newtonian medium, and a preliminary examination of the questions of discontinuous motion and streamline form. Chapter II, is devoted to the consideration of viscosity and skin-friction, the argument being largely founded on dimensional theory; and Chapter III, consists in the main of an account of the Fulerian hydrodynamic theory, in which the mathematical demonstrations are in general taken for granted;[1] this chapter also includes some further discussion of the phenomenon of discontinuous flow and a review of the controversy relating to same.

Chapter IV, consists in most part of an investigation on peripteral motion,[2] dating from the year 1894-5 and offered to the Physical Society of London in the year 1897, but rejected.[3]

  1. The reader is referred to "Hydrodynamics" (Horace Lamb, Cambridge University Press) for the complete mathematical treatment: a work to which the author desires to acknowledge his indebtedness.
  2. A term proposed and employed by the author to denote the type of fluid motion generated in the vicinity of a bird's wing, or the supporting member of an aerodrome essential to its supporting function (lit. "round about the wing," Gr. περι and πτερόν). The term has an architectural signification which can by no possibility clash with its present usage.
  3. The rejection of this paper was probably due to an unfortunate selection of the readers to whom it was submitted. The names of the Society's readers are not disclosed, but from the wording of the reports (which the author is not at liberty to quote), it would seem that the recognised application of the Newtonian method (as in the theory of propulsion) was a thing unknown to them.