Page 141 - Theory and Design of Air Cushion Craft

124 Steady drag forces

0.04

Craft speed v,=2m/s
Finger type skirt
0.03

0.02

0.01

Firm snow
10 15 20 25
Skirt drag/Craft weight x 100(%)

Fig. 3.36 Skirt ground interference drag as a function of surface condition and ACV equivalent air gap /?, K.
[37]

Test on concrete surface

o
o
- 4 h
x

2 -

2 4 6 8 10
v s (m/s)

Fig. 3.37 Skirt ground interference drag as a function of /? f/f and craft speed.

3.14 Problems concerning ACV/SES take-off

The acceleration capability of ACV/SES through hump speed is a very important
design feature. Designers and users are therefore often concerned about the 'take-off'
capabilities of ACV/SES running over water, because the hump speed is only one-