Page 191 - Theory and Design of Air Cushion Craft
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174 Stability
Fig. 4.40 The plough-in phenomenon of British SR.N6 in tests.
that the speed decreases, followed by large pitching down and heeling angle, as
well as stern pitching up tendency so as to enlarge the drifting angle.
The principal author has had a number of such experiences; for example, the 5 t
ACV model 711-11 would plough-in on calm water (or in a breeze) at a speed of
70-80 km/h. In the case where the craft was travelling downwind, then the proba-
bility of plough-in would be over 90%. Violent slamming would occur to the craft
and lead to speed degradation from high speed (about 80 km/h) to off cushion
speed (about 5 km/h) in 2-3 seconds. Such high deceleration accompanied by the
