Page:Aerial Flight - Volume 2 - Aerodonetics - Frederick Lanchester - 1908.djvu/33

sufficient magnitude to be of consequence ; if, however, the mica plate is defective, the path of flight will be of spiral form, and if the defect is serious the spiral may become a curve of decreasing radius and instability may thus result.

The sense of direction of a ballasted aeroplane may be sometimes improved by the addition of a small fin near the front edge, conveniently attached to the ballast (Fig. 7). With the same end in view, the front corners of the plane may be "dog-eared" slightly (Fig. 8), a procedure that is otherwise advantageous. The simple ballasted plane has no " right side up," if properly

Fig. 7.

Fig. 8.

launched it will fly with either face topmost, but there is some risk that in the act of launching the reaction will be downwards instead of upwards, in which case the path of flight is entirely modified, in a manner that will be explained later in the work. In the case of the plane with the corners dog-eared (upwards), this does not apply to the same extent, and the launching may be effected with greater ease and certainty. Although the above expedients may sometimes be found advantageous it is the better plan to reject at the outset mica that is perceptibly on the twist or otherwise contorted.

 

§ 7. Ballasted Aeroplane. Interaction of Motions in and about the co-ordinate Axes.—It is of interest to summarise the inter-{[c|11}}