Page 181 - Theory and Design of Air Cushion Craft

164 Stability

occurs with heeling. This phenomenon also happens on an ACV hovering on a water
surface as shown in Fig. 4.28. In the case where the ACV heels on the water surface
as shown in Fig. 4.28, the cushion pressures for left/right cushion compartments are
rather different, thus it causes a different water surface deformation for each of the
compartments. The water hollow under the left cushion compartment is deeper than
that in the right compartment and the water displaced by the hollow is equal to the
lift caused by the cushion pressure on each side. Thus it can be seen that the restoring
moment and the drifting force are caused by the different cushion pressure in the left
and right cushion compartments.

Side slip

Fig. 4.26 Heeling of an ACV without air cushion compartmentation on water.
\

Fig. 4.27 Heeling of an ACV with air cushion compartmentation on rigid surface.

Fig. 4.28 Heeling of an ACV with air cushion compartmentation on water.