Page 9 - Theory and Design of Air Cushion Craft

viii Contents

3.8 Sidewall water friction drag 104
3.9 Sidewall wave-making drag 111
3.10 Hydrodynamic momentum drag due to engine cooling water 115
3.11 Underwater appendage drag 115
3.12 Total ACV and SES drag over water 117
3.13 ACV skirt/terrain interaction drag 121
3.14 Problems concerning ACV/SES take-off 124
3.15 Effect of various factors on drag 130

4. Stability 136
4.1 Introduction 136
4.2 Static transverse stability of SES on cushion 137
4.3 SES transverse dynamic stability 152
4.4 Calculation of ACV transverse stability 163
4.5 Factors affecting ACV transverse stability 168
4.6 Dynamic stability, plough-in and overturning of hovercraft 173
4.7 Overturning in waves 185

5. Trim and water surface deformation under the cushion 187
5.1 Introduction 187
5.2 Water surface deformation in/beyond ACV air cushion over
calm water 190
5.3 Water surface deformation in/beyond SES air cushion on
calm water 197
5.4 Dynamic trim of ACV/SES on cushion over calm water 200

6. Manoeuvrability 205
6.1 Key ACV and SES manoeuvrability factors 205
6.2 Introduction to ACV control surfaces 207
6.3 Differential equations of motion for ACV manoeuvrability 217
6.4 Course stability 224
6.5 ACV turning performance 227

7. Design and analysis of ACV and SES skirts 232
7.1 Introduction 232
7.2 Development and state of the art skirt configuration 235
7.3 Static geometry and analysis of forces acting on skirts 250
7.4 Geometry and analysis of forces in double or triple bag stern
skirts 258
7.5 Geometry and forces for other ACV skirts 260
7.6 Analysis of forces causing the tuck-under of skirts 261
7.7 Skirt bounce analysis 267
7.8 Spray suppression skirts 270
7.9 Skirt dynamic response 271

8. Motions in waves 273
8.1 Introduction 273