Page 146 - Theory and Design of Air Cushion Craft

Problems concerning ACV/SES take-off 129

RIW
0.10

0.06

Z s: see fig. 3.41
0.02

0.2 0.6 1.0 Fr,

Fig. 3.42 Influence of the vertical distance between the base-line and lower tip of stern seal Z s on drag ratio
R/W.

Fig. 3.43 Various locations of balanced type stern seal. 1, 2, 3: flexible connection seal; AB, A'B': two modes
for solid seal.

stern seal took off very easily because of good yielding features of the skirts in
waves. After a time, the craft was extended by 6 m and LJB C stretched from 4 to
5.05 and reduced cushion pressure-length ratio from 17.6 to 14.6 kgf/m. For this
reason, the peak wave-making drag was reduced drastically and moved the hump
speed to larger Fr. Therefore, the engines could supply more power because of the
large magnitude of the hump speed. Take-off performance improved greatly, with
shortened time for take-off and less spray.