Page:Aerial Flight - Volume 1 - Aerodynamics - Frederick Lanchester - 1906.djvu/57

Rh '''§ 27. Mutilation of the Streamline Form (continued).'—In Fig. 16, A and B, the consequences of truncating the fore body, or entrance'', of a streamline body are indicated diagrammatically. If, as in A, the mutilation be slight, the result may be merely a local disturbance of the lines of flow. A surface of discontinuity will probably arise, originating and terminating on the surface of the body in the manner shown. It is possible that if the streamline body be travelling at something approaching its critical velocity (at which even in its complete form it is on the point of giving



rise to discontinuity), a minor mutilation such as here suggested might have more serious consequences.

If the greater part of the entrance be removed, as shown at B, the surface of discontinuity generated quits the body for good, and the resistance becomes immediately as great as that of a normal plane of area and form equal to that of the section. This is in harmony with the experiments of Button and Dines, to which reference has already been made (Fig. 17), the three bodies shown being found to offer the same resistance within the limits of experimental error.

It is evident that the dictum of the late Mr. Froude, that it is