Theory and Design of Air Cushion Craft (eBook)

Cover 1
Contents 8
Chapter 1. Introduction to hovercraft 16
1.1 Hovercraft beginnings 16
1.2 ACV and SES development in the UK 24
1.3 ACV and SES development in the former USSR 37
1.4 US hovercraft development 40
1.5 ACV and SES development in China 47
1.6 SES and ACV developments in the 1990s 54
1.7 Applications for ACV/SES 56
1.8 The future 60
1.9 SES and ACV design 61
Chapter 2. Air cushion theory 63
2.1 Introduction 63
2.2 Early air cushion theory developments 65
2.3 Practical formulae for predicting air cushion performance 70
2.4 Static air cushion characteristics on a water surface 81
2.5 Flow rate coefficient method 86
2.6 The 'wave pumping' concept 88
2.7 Calculation of cushion stability derivatives and damping coefficients 91
Chapter 3. Steady drag forces 99
3.1 Introduction 99
3.2 Classification of drag components 99
3.3 Air cushion wave-making drag (Rw) 101
3.4 Aerodynamic profile drag 111
3.5 Aerodynamic momentum drag 111
3.6 Differential air momentum drag from leakage under bow/stern seals 112
3.7 Skirt drag 113
3.8 Sidewall water friction drag 119
3.9 Sidewall wave-making drag 126
3.10 Hydrodynamic momentum drag due to engine cooling water 130
3.11 Underwater appendage drag 130
3.12 Total ACV and SES drag over water 132
3.13 ACV skirt/terrain interaction drag 136
3.14 Problems concerning ACV/SES take-off 139
3.15 Effect of various factors on drag 145
Chapter 4. Stability 151
4.1 Introduction 151
4.2 Static transverse stability of SES on cushion 152
4.3 SES transverse dynamic stability 167
4.4 Calculation of ACV transverse stability 178
4.5 Factors affecting ACV transverse stability 183
4.6 Dynamic stability, plough-in and overturning of hovercraft 188
4.7 Overturning in waves 200
Chapter 5. Trim and water surface deformation under the cushion 202
5.1 Introduction 202
5.2 Water surface deformation in/beyond ACV air cushion over calm water 205
5.3 Water surface deformation in/beyond SES air cushion on calm water 212
5.4 Dynamic trim of ACV/SES on cushion over calm water 215
Chapter 6. Manœuvrability 220
6.1 Key ACV and SES manœuvrability factors 220
6.2 Introduction to ACV control surfaces 222
6.3 Differential equations of motion for ACV manœuvrability 232
6.4 Course stability 239
6.5 ACV turning performance 242
Chapter 7. Design and analysis of ACV and SES skirts 247
7.1 Introduction 247
7.2 Development and state of the art skirt configuration 250
7.3 Static geometry and analysis of forces acting on skirts 265
7.4 Geometry and analysis of forces in double or triple bag stern skirts 273
7.5 Geometry and forces for other ACV skirts 275
7.6 Analysis of forces causing the tuck-under of skirts 276
7.7 Skirt bounce analysis 282
7.8 Spray suppression skirts 285
7.9 Skirt dynamic response 286
Chapter 8. Motions in waves 288
8.1 Introduction 288
8.2 Transverse motions of SES in beam seas (coupled roll and heave) 294
8.3 Longitudinal SES motions in waves 309
8.4 Longitudinal motions of an ACV in regular waves 323
8.5 Motion of ACV and SES in short-crested waves 337
8.6 Plough-in of SES in following waves 339
8.7 Factors affecting the seaworthiness of ACV/SES 343
Chapter 9. Model experiments and scaling laws 357
9.1 Introduction 357
9.2 Scaling criteria for hovercraft models during static hovering tests 358
9.3 Scaling criteria for tests of hovercraft over water 363
9.4 Summary scaling criteria for hovercraft research, design and tests 367
Chapter 11. Determination of principal dimensions of ACV/SES 392
11.1 The design process 392
11.2 Role parameters 393
11.3 Initial weight estimate 394
11.4 First approximation of ACV displacement (all-up weight), and estimation of weight in various groups 399
11.5 Parameter checks for ACV/SES during design 412
11.6 Determination of hovercraft principal dimensions 414
Chapter 12. Lift system design 420
12.1 Introduction 420
12.2 Determination of air flow rate, pressure and lift system power 422
12.3 Design of fan air inlet/outlet systems 428
12.4 Lift fan selection and design 435
Chapter 13. Skirt design 448
13.1 Introduction 448
13.2 Skirt damage patterns 448
13.3 Skirt failure modes 450
13.4 Skirt loading 452
13.5 Contact forces 456
13.6 Selection of skirt material 457
13.7 Selection of skirt joints 462
13.8 Assembly and manufacturing technology for skirts 464
13.9 Skirt configuration design 466
Chapter 14. Structural design 473
14.1 ACV and SES structural design features 473
14.2 External forces on hull – introduction to the strength calculation of craft 476
14.3 Brief introduction to the structural calculation used in MARIC 480
14.4 Calculation methods for strength in the former Soviet Union 482
14.5 Safety factors 488
14.6 Considerations for thickness of plates in hull structural design 489
14.7 Hovercraft vibration 589
Chapter 15. Propulsion system design 502
15.1 Introduction 502
15.2 Air propellers 522
15.3 Ducted propellers and fans 530
15.4 Marine propellers 535
15.5 Water jets 551
15.6 Power transmission 579
15.7 Surface contact propulsion 589
Chapter 16. Power unit selection 592
16.1 Introduction 592
16.2 Powering estimation 600
16.3 Diesel engines 603
16.4 Gas turbines 611
16.5 General design requirements 619
16.6 Machinery space layout 621
16.7 Systems and controls 622
16.8 Operation and maintenance 622
Index 633