Page:Aerial Flight - Volume 2 - Aerodonetics - Frederick Lanchester - 1908.djvu/220



§ 109. Preliminary.—In the foregoing chapters many results individually of importance have been demonstrated; the main consequence of these results—the definite proof of the automatic stability of a properly designed aerodone—is alone a matter of very great moment. The establishment of the laws of stability in a form immediately available to the designer, cannot fail to have a far-reaching influence on the future of mechanical flight, and on the development of the flying machine for aerial navigation.

In the present chapter we shall first carefully review the theory, especially with regard to its aerodynamic foundations, which will be examined minutely, and subsequently any unaccounted factors and limitations, where such limitations exist, will be discussed. We will then briefly consider the application of the theory to the problem of mechanical flight, dealing with such points as the influence of the mode of propulsion, the rate of damping of the phugoid oscillation, the law of corresponding speed and the conduct of model experiments, departures from the elementary type, etc., etc.; afterwards discussing the experimental verification and employment of the theory of lateral stability of Chapter VII., and in conclusion a brief note will be given of the historical development of the present aerodonetic theory and of its experimental confirmation.

§ 110. Aerodynamic Basis of the Phugoid Theory.—From a strictly logical point of view the series of investigations forming the subject matter of the present volume begin at the commencement