Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/192

§124 requires that the load should be distributed throughout the region in question (compare § 92), a condition that could be only approximated in practice by the employment of a number of surfaces, such as indicated diagrammatically by the stouter lines shown in the figure. The form of these surfaces for the conditions stated is that of a series of concentric cylindrical sections.



§ 125. Peripteroid Motion in a Simply Connected Region.—The problem presented in the case of an aerofoil of finite lateral extent is, from the present standpoint, one of some difficulty, inasmuch as the region under these circumstances becomes simply connected, so that cyclic motion can no longer exist, and rotation in some form constitutes the only solution. It is, of course, conceivable that flight in an inviscid fluid is theoretically impossible.

Let us first study the case of a viscous fluid, and then, by