Page 168 - Theory and Design of Air Cushion Craft

Static transverse stability of SES on cushion 151

0.04 -

0.03 -

0.02 -

0.01 -

2 4 6 8 0(°)

Fig. 4.17 Static transverse stability for three craft of series 717.

Table 4.4 The leading particulars for three SES type 717

Item Symbols Dimensions 717 717A 717C
Craft weight W t 13.7 15.95 18.20
Cushion length 4 m 13.2 15.2 17.3
Cushion beam fi c m 3.5 3.5 3.5
Cushion lib ratio lJB e 3.77 4.34 4.94
Cushion pressure length ratio PA kgf/m 19.93 17.31 15.38
Cushion pressure N/m 2 2630 2630 2660
PC
Flow coefficient Q 0.00757 0.00658 0.00570
VCG KG m 1.27 1.27 1.27
Bow and stern seals clearance Z m 0.15 0.15 0.15
b,s
Sidewall midship deadrise angle a deg 60 60 60
Sidewall flare above hard chine ft deg 89 89 89
Sidewall keel plate width 5, m 0.12 0.12 0.12
correct, therefore, to say that the transverse stability will definitely deteriorate with
increasing cushion length/beam ratio; one has to analyse the particular craft design to
identify its sensitivity to this possible problem.

Summary
1. The calculated results of the static transverse stability of craft by means of this
method agree well with the experimental results, therefore it can be recommended
to use this method to check and analyse the static transverse stability of the
designed or constructed SES.