Page:Aerial Flight - Volume 2 - Aerodonetics - Frederick Lanchester - 1908.djvu/429

Rh boomerang that will come into view as the result of the precession in the manner indicated in successive positions shown, (b), (c), and (d). As a consequence the path of the boomerang will take an upward trend. Figs. 194-5, and it will continue to rise until its kinetic energy is absorbed as potential, when it will

Fig. 194.

slide back along a similar path, and fall at the feet of the thrower. Fig. 194 (a).

When we take account of the forward displacement of the centre of pressure as well as its lateral displacement, we have

Fig. 195.

superposed on the motion as above depicted a further motion partaking of that of the previous example, the disc, and the flight path, instead of being in plan a straight line (Fig. 195), becomes a curve (Fig. 196).

If the plane containing the boomerang at the instant of projection is not horizontal, the flight path undergoes considerable modification. The form of trajectory given in Figs. 195-6 is not