Tham khảo tài liệu 'theory design air cushion craft episode 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 146 Stability 1. width of keel plate of sidewall Bx 2. deadrise angle of midships section of sidewalls a 3. height of hard chine line amidships ỉk 4. width of sidewall Bsw 5. flare angle of sidewall above hard chine P 6. external draft of the sidewall t0. From Fig. we have B Bị t0 cot a BsJBc - Bx zo cot d IBc In general B can be kept as a constant t0 can be determined by the cushion pressure pc so we can take the parameters a p and B as variables the variable range of which is shown in Table . The calculation results are shown in Fig. . In order to investigate the effect of Bị on stability we obtain the second set of variables shown in Table . The basic parameters were kept the same as for craft type 717 such as principal dimensions cushion pressure length ratio flow rate coefficient flare angle of sidewall section above the hard chine the gap between the lower edge of the bow stern seals and the base-line fan characteristic etc. except the parameters a and p. Then the static transverse stability could be calculated. The results are as shown in Fig. . From the figures it is found that 1. The static transverse stability of craft at large heeling angles is strongly affected but not at small angles. Table The variable range of a fi a 40 45 50 55 60 m 55 60 65 50 60 65 60 65 70 60 65 70 65 70 BJBC Fig. Geometrical parameters for sidewalls. static transverse stability of SES on cushion 147 Fig. Influence of parameters a p on relative heeling righting arm. Fig. Influence of parameters a p on relative heeling righting arm. 2. Linearity in the relation of the righting arm with respect to the heeling angle only exists at small heeling angles to about 3 4 therefore it is convenient to take the relative metacentric height h h Bc where h is the metacentric height and Bc is the cushion beam as one of the stability criteria of the craft. 3. The width of the keel plate on .
