Air Cushion

8/2/2019 Air Cushion

1/20

Theory and Designof Air Cushion CraftLiang YunDeputy Chief Naval Architect o f the MarineDesign & Research Institute of China

Alan Bliault5hell International Exploration and ProductionHollan

A member of the Hodder Headline GroupLONDONCopuhlibhcd in North, Central and South America by

John Wilcy & Sons Inc.. New York . Toronto


2/20

Contents

du ct io n to hovercraftHovercraft beginningsACV an d SES development in the U KACV an d SE S development in the former USSRIJS hovercraft developmentACV a nd SES development in ChinaSES and ACV developments in the 1990sApplications for ACVISESThe futureSES and ACV design

2. Air cushion theory2.1 Introduction2.2 Early air cushion theory developments2.3 Practical form ulae for predicting a ir cushion perform ance2.4 Static air cushion characteristics on a water surface2.5 Flow rate coefficient m etho d2.6 Th e 'wave pum ping' conce pt2 .7 Calculation of cushion stability derivatives and dam pingcoefficients3. Steady dr ag forces3.1 Introduction

3.2 Classification of dr ag com po nen ts3.3 Air cushion wave-making drag (R , )3.4 Aerod ynam ic profile dr ag3.5 Aerodynamic mo me ntum drag3.6 Differential air m om entum drag froln leakage und er bowlsternseals3.7 Skirt dr ag


3/20

vii i Contents3.8 Sidewall water friction dr ag3.9 Sidewall wave-making dra g3.10 Hyd rodyna ~nic n oin ent um rag due to engine cooling watcr3.11 Underwater appcndagc dra g3.12 Total ACV a nd SES drag over watcr3.13 ACV skirtlterrain interaction drag3.14 Problems concerning ACVlSES take-off3.15 Effect of va rious Factors on dra g

4. Stability4.1 lntroduction4.2 Static transverse stability of SES on cushion4.3 SE S transverse dynam ic stability4.4 Calculation of ACV transverse stability4.5 Fac tors affecting ACV transv crsc stability4.6 Dynamic stability, plough-in and overturning or hovercraft4.7 Overturn ing in waves

5. Trim and water surface deformation under the cushion5.1 lntroduction5.2 Water surface deforination inlbeyond AC V air cushion overcalm water5.3 Water surface deformation inlbeyond SE S air cushion o ncalm water5.4 Dynam ic trim of ACV lSES on cushion over calm water

6. Manceuvrability6.1 Kcy ACV an d SES manceuvrability facto rs6.2 Introduction to ACV c ontrol surfaces6.3 Differential equations of motion for ACV manceuvrability6.4 Cou rse stability6.5 ACV turning performance7. Design and analysis of ACV a nd SE S skirts

7.1 lntroduction7.2 Development and state of the art skirt configuration7.3 Static geom etry an d analysis of forces acting o n skirts7.4 Ge om etry and analysis of forces in double o r triple bag sternskirts7.5 Geom etry a nd forces for othcr ACV skirts7.6 Analysis of forces causing the tuck-und er of skirts7.7 Skirt bounce analysis7.8 Spray suppression skirts7.9 Skirt dynam ic response8. Mo tion s in waves8.1 Introduction


4/20

Contents i x

8.2 Transverse motions of SE S in beam seas (coupled roll and heave)8.3 Loilgitudinal SES mo tions in waves8.4 Longitudinal motion s of an ACV in regular waves8 .5 M ot ion o f ACV an d SE S in short-crested wm es8.6 Plough-in of SES in following waves8.7 Factors affecting the seaworthiness of ACVISES

9. Model experiments an d scaling laws9.1 Introduction9.2 Scaling criteria for hovercraft m odels d uring static hovering tests9.3 Scaling crite ria Tor tests of hoverc raft over wate r9.4 Su mm ary scaling criteria for hovercraft research, design an d tests10. Design methodolog y and performan ce estimation10.1 Design methodology10.2 Stability requiremen ts an d stand ards10.3 Req uirements for damag ed stabiliiy10.4 Requirements for seaworthiness10.5 Requirements for habitability10.6 Kequirements for ma nau vrab ility10.7 Ob staclc clearance capability

11. Determination of principal dime nsions of ACV ISES11.1 Th e dcsign process11.2 Role parameters11.3 Initial weight estimate11.4 First approxim ation of ACV displacement (all-up weight),an d estimation of weight in various groups11.5 Parameter checks [or ACVISES during dcsign11.6 Determ ination of hovercraft principal dimen sions

12. Lift system design12.1 Introduction12.2 De terinillatio n of air flow rate, pressure a nd lift system power12.3 D esign of f an air inletloutlet systcms12.4 Lift fan selection and design

13. Skirt design13 .l Introduction13.2 Skirt damage patterns13.3 Skirt failure mod es13.4 Skirt loading13.5 Contact forccs13.6 Selection of skirt ma terial13.7 Selection of skirt joints13.8 Assembly and ma nufacturing technology for skirts13.9 Sk irt con figura tion design


5/20

X Contents14. S tructu ral design14.1 ACV an d SE S structur al design features14.2 External forces on hull int ro d u ct io n to the st rengthcalculatio~l f craft

14.3 Brief introdu ction to the structur al calculation used inM A R I C14.4 Calculation methods for strength in the former Soviet Union14.5 Safety facto rs14.6 Considerations for thickness of plates in hull structural design14.7 Hov ercraft vibration15. Prop ulsion system design15.1 Introdnction15.2 Air propcllcrs

15.3 Du ctcd propellers and fans15.4 Marine propellers15.5 Waterjcts15.6 Power transmission15.7 Surface contact propulsion16. Power unit selection16.1 lnt roduct io~l16.2 Pow ering estim ation16.3 Diesel engines

16.4 G as turbines16.5 General design requirements16.6 Machinery space layout16.7 Systems and controls16.8 Operation an d maintellancc


6/20

Index

Page numbers in bold rzfcr to figures andpage numbers in italic indicate tablcs.AALC 150 50 !node1 350Acceleration 124, 468Acceleration/frequency tolrrat~onimits 369Accidents 185ACVs 13hovercrat-t 13, 13, 14Accommodation space requirements 399ACV

accidents 13applications 41-5calculation ol' transverse stability 1638 .166-8development in UK 9-21dimensions of 386-7, 389-YOdynamic trim 190Factors affecting transverse stability168-72longitudinal motion in regular waves for308 22manceuvrability 206moving over deep water 190 3operation modes over ground terrain 122over shallow water 1 9 6 6water surfacc deformation inlbeyond aircushion over calm water 190-3weight of 389-90Aerodynamic force and momcnt 221, 223Aerodynamic momentum drag 96

Aerodynamic profile drag 95-6, 96Aerodynamic yawing moment 226Air clearance 50, 62, 65characteristic curves 424Air cushion 2, 42adiabatic stiffness coefficient S48

charactcristics 72characteristics curves 70. 71craft, classilication 6flow rdtc due to mass change rate of S01pcrfortnanceon rigid surface 51prediction 55-65pressure distribution 472, 472stability 76-83

supported vehicles, see ACVsystem 2824. 299-301, 313-17theory 48-83

early developments 50 5Air duct 70, 71,424calculation 410-12charactcristics 78configuration 413loss coelficicnt 411non-dimensional charactcristic curves345-6non-dimensional characteristics 350system 412,413valves 2 16Air flow coellicient 64Air tlow rate 1 334, 339,340coefficient 149determination 407 10distribution effect 339Air gap 83,128Air inlet

inclination angle 417of integrated liftipropulsior~ ystems 414pressure losses 414Air jet momcnt from cushion to atmosphere286 7

Air jet propulsio~~0 6 7Air jet strean~lines 4


7/20

Air leakage 79flow rate of 300, 3 14 15under SES sidewall 67Air lub ric ati o~ l -3, 9. 48Air propellers 507 14blade erosion and its mitigation 514-15blade types and efliciency 5 0 9 10construction 513diamctcrltip speed relationship 511selec tion 510, 51 1weight 513Air p rop uls ors 21 1-14Air rudders 217Air streamlines 55Air supply to bow skirt arca 328Alum inium alloy 459

Amphibious capability 41 ,4 8Am phibious hovercraft 1, 3, 4. 4, 274Anti-plough-inhydrofoils 327requirements 453Anti-roll systems 335-6Anti-spray plate 335An ti-sub ma rine vessels 41, 42AP1.RR 15, 20, 21. 40. 41, 213 , 507, 520 , 592 ,594A P I . 8 8 4 0 0 4 4Aprons 271Archirnedes' principle 66Arctic trans port 45Axial flow pumps 559Bag an d linger bow seal 247Bag and f inger bow skir t 153,24 7,24 9Bag a nd finger skirt 49. 52, 55, 59, 62. 71.129,238,243. 262 ,451equations for static geometry and forceanalysis 251 5forces aclirig on 263model tests 250-1static geometry 250-7supporting forces acting o n oints 2 5 L 7Bag an d nozzle skirtchain connection lor 237flexible diaphragm connection 237Bag an d periccll skirt 243, 244, 261Bag chord length 251Bag cus hio r~ ressure ratio 63, 262Bag pressure 59Bag ski rt 49Bag ste rn seal 248

Index 619Bag stern skirt, geometry an d analysis offorces in d ou hlc o r lriple 258-60Bag to cush ion pressure ratio 62, 65. 251coefficient 60Beam seas, difkre ntial equ ations of coupled

roll and heave motion o l SES in 291Rearings 571Bell Aerospace Corporation 25, 29Bcll-Halter Corporation 29Bell Tcx lron Jeff (B) 599Bending 469Bending mom ent 470. 470, 471acting on m idship section 469-70cushion-bornc operation 470hull-borne operation 471transverse 471Bernoulli cq uation 53,4 12, 495Bernoulli theory 67BH.7 14, 15.2 39BH .11029 30, 29Bla de elem ent theory 499-500. 501, 524Blade velocity vector diagram 496Bliss, Demlis l l , 233Blohm a nd Voss 40Boundary layer thickness 54Bow acceleration 307Bow finger tip linc 327Bow hydrofoils 33 34 .3 3 4Row seal during tak e off, watcr contactphenomenon of 105Bow skirtetnergencc 302tuck-in 326Bow skirt areaair supply to 328relative to stern 327Bow skirt finger tip 258Rowistern acceleration. frequency responsefor 32 1Bowistern sealan d basc-line gap 149during heeling, righting moment of 155equipment 326-7heave stiffness for 328relative gap 150Bowlstcrn seal drag 102 3B A . Kolczacv method 103M A R I C method 102

Rin-lchi Mara o mcthod 103Bowlstern seals 246-9interaction 188


8/20

620 IndexBowlstern skirts. height determination 453Brodrene Aa 3 9 4 0British Hovel-craft Corporation 10Britten-Norman 12Cabin 370, 373

volu~ne 1 2Captured air bubble 2 3. 246Cargo vessels 40Catamarans l , 42-3, 113Cavitation 522 4. 523, 531. 537, 545. 561

water jets 556 7Cavitation tunnel 552Centrifugal fans 4259, 507

aerodynamics characteristics 426Centrifugal pumps 558CG 359,359,461,463,464,469, 564China. ACV and SES dzvelopment 32-9Chong Cheng Shipping Company 35Cirrus 39Cohblcstnnc effect 322, 323, 324Cockerell. Sir Christopher 3, 7, 9. 48, 233,

275C:oeHicient f SOCoefficient of addcd mass 278Cocfficicnt of clongation 347Commercial design parameter5 378Co~npuler rogram for dilrerential equationsof rnolion 290Constant cushion volume 74Constr~~ctionost per unit seat 398Contact forces 441- 2C:ontinuity equation of Iiow 282Control equipment 208Control surfaces 207-17

fcatures 21 6state of the art 2 1 6 17. 216

Control bystem colnponeiits 563Controllable pitch air propellers (ductedpropellers) 21 1-13Coordinate system 297-8, 298, 308, 309Correction coefficient of wetted surface 109Correction coefficient of wetted surface arca

of sidewalls 110Couplings 571Coursz-keeping ability

and handling 374under qua~.tcring r beam winds 375

Course stability 224-7analysis 225-7dynamic 225

static 224-5vertical fins for 208. 209see also Stability

Cushion aircompressibility 321, 322-3How rate and pressure 71

Cushion altenualion coefficient vs. craftspccd 465

Cushion-hornc uper ' onbending nmlnent 470in high wews 3 36 8

Cushion compartmentation l634. 169,170Cushion depth, damping effect of 323C:ushion dcpthfbcam ralio 359Cushion flow coefficient 401Cushion llow 1-ate 334Cushion fluw rate coefficient 62Cushion force 214-16, 222-3, 284Cushion geometry 49Cushion height 359Cushion heightlwidth ratio versus transvel.sc

roll stiffness 360Cushion lcngtbibeani ratio 87. 101, 132,

150-1, 330-1,332,357,400Cushio~lift power coefficient 62Cushion mome11t2223 . 284Cushion pi-cssure 41, 50, 5940, 73, 79, 80,

89analysis of forces acting on fingers under264

and heave amplitude R1during plough-in 326tluctuations 277. 324spatial distribution 278trends 401

Cushion prcssure coefficient 60, 62Cushion pressure distribution 472, 473

\S. ship speed 181Cushion przssurcllengtl~ atio 89, 132, 149.400Cushion pressure ratio 344Cushion stalic prosure 506, 506Cushion system fans 507Cushion wave-making drag 98Cushioncraft CC1 12Cushioncraft CC2 12Cushiollcraft CC5 12, 507Damping coelficienl 7 6 83, 278

calculation 77-80cxperimer~talmethods 80 2


9/20

Index 621

Dam ping effectof cushion depth 323on seaworthiness 333-5Dcck area 41-2Deck plates, dcsign load 473d e Laval, Ciustav 2D csig n 4 6 7concepts 190

inertial loa ds 461-3leading particulars selection prior to 402loads 469lnethodology 353-5parameters 354, 377. 378-9checks during design 397 9process 377sequence 377Detachable b owistcrn scals 249Lliaphragms 251installation 451of D-sha pe bags 264 5Diesel engines 57 9,5 81 , 588-96cooling systems 590-4exhausts 595lubrication system 595maintenance 610-1 1number of engines and layout 588-90.589ope ration 607-10reliel' valves 595vibra tion 5 9 4 5Differential air mo men tum drag fromleakage und er howlstern seals 97Differential equations of couplcd roll andheave mo tion in beam seas 291

DilTerential equ ation s of longitudinalnlotio n in wavcs, block d iagram 297. 305Differential equations of motion 223 4,281-90. 304-7, 317-18co n~ pu tcr rogram Sor 290formation 219-20in regular waves 313Dimcnsionsde termina tion 354, 37 7 40 4limitations 399of ACV 386 7. 389-90.403Disc loading 498Disp lacem ent, ACV 384-97Docking. strcngth calculation 473Dragcomponents, classification 84-5forccs 84-134in head seas 338

in waves 338of non-flush sca-watcr strainers 116 17of rudders 1 15-1 hof shafts (or quill sh afts) and boss I l hof strut palms 116over calm water 120, 130srr nlsu llyd rody nam ic drag: Kesidualdra g; Seal dn->*g; kir t dr ag ; Total drag :Wave-making drag1~)ragIweight atio 94Drivcr tcchniquc 185D-shape hags 184 ,184,25d iaphragm s of 26 6 5

D T N S R D C 28Duc t system character ist ic 3 2 3 4Ilucted falls 515-20duct dcsign 518-19fan selection 5 17stato rs 518Du ctcd prop cllcrs 21 1 13. 507. 515Ducted propulsors 274. 520Dyn amic motion s 273-341. h04historical rcvicw 2 7 4 6Dynamic transverse righting mom ent of SES159Dynamic trim 156on cushion over calm water 200 4, 2 0 1over calm water for ACV 308-12prediction over calm water 200-3Elas tic n~od ulu s347Electrical cquipmcnt, wcight of 396Elevons 208-10Energy equation 141Enginccooling water, hydrodynamic momentumdrag due to 115lhilurc modes and clk cts 606heating for suh-zero temperatures 584-5monitoring and control systern 6U8ope rating characteristics 581-2power ranges 579starting 605

systclns an d controls 607Equations of motion 217Equilihrium equationUS brccs 2 6 5 6static forces 309-10Euler num ber 344Extended szgmen t skirts 245, 244. 260External a ir stream lines 180


10/20

622 IndexExternal fol-ccs on hull 461-5External response 327Fan air duct

characteristic 323charactcristic equation 310Fan air inletloutlet system 413-19Fan blade regulation 21 6Fan characteristic cquatiotl 142Fan charactcristic~ 84Fan curve gradient 327Fan flow rate 172Fan inlet

loss coefficient 412pressure recovery coefficient at 412system 413-17

Fan outlet system. SES 419Fan overall pressure 412-13Fan speed 148Fans

aerodynamic characteristics 423air How rate 430centrifugal 425-9, 507cushion system 507efficiency-flow rate characteristics 431horizontal arrangement 418-19HVAC systems 423impellcr diameter 428-9noise reduction 430non-dimensional characteristic curves

345-6non-dimensional characteristics 350off-design operation 422overall pressure-tlow rate characteristics

431overall pressure head 410 13pressure-How characteristic curve 430selection of type 420 5. 421by means of specific speed 426-8vertical arrangement 418see also Ducted fans; Lifl fans

Fast Attack SES 44Fast vessels 42Fatigue endurance of transmission shafts

569-7 1Finger bow skirt 247Finger height ratio 454Finger inclination angle 454Fins 217Flagellation 437Flat lilt fan 323 4

Flexible bow seal 135Flexible bowlstern seal 153 4Flexible skirt 11, 28, 47-9. 52, 56, 91, 100,

127, 173,232,235advantages 232development 233

Flow coefficient 407, 408Flow continuity equation 78. 141

for small perturbations 315-17Flow modes in heaving motion 77. 78Flow rate

air lcakage 300air leakage and cross-llow, small

perturbation equation Cor 314 15coefficient 49, 71-3. 345continuity equation 310-12due to mass change ratc of air cushion

301equation 141minimum calm water drag 409-10

Flow rate-pressurc head linear equation withsmall perturbation 313-14

Flullering 437Foil-shaped appendages l l SFootprint pressure 41France 40Frequency response

bowistern acceleration 321cushion prcssure 293heave acceleration 292,319heave amplitude 318-19,318heave motion 77pitch amplitude 319-20. 319. 333roll amplitude 293wave exciting force 320wave exciting moment 320

Froude Krilov hypothesis 276-7,296Frotide number 85, X7,91.92, 102, 103, 109,

110, 115, 177,181, 196,338, 348-9and wiwe profile 189Froude scaling relationship 342Fuel and oil, weight of 396Fuel consumption 397-8Fuel filtering 606Fucl system 505Gap height 12.1Gas turbines 579,583, 596-603,597,602

air intake filtration 601-3, 603air intake How requirements 600alarms 605


11/20

inflow distortions 600layout a nd engine sclcction issues 598-9mainten ance 610 l lnoise 603operation 610protection fro m foreign object damag e600-1Gea rbox 572-3,575power flow diagram 574Generators 595Geo metrical dime nsions 297-8, 298, 308, 309Germany 40Goldstein factor 525, 526

Corko~~rhunin27GriKon Hovercraft 25GRP 38,38, 39,459Gu ide wheels on laud 210-11,211Habitability requirements 365-74Halter M arine Inc. 29Harbin Shipbuilding Engineering Institute(HSEI) 32 ,48HD-I 12HD-2 194Head winds, performance 341Hezt generation 28Heave 273Heave acceleration, frequency response 292,319Heave amplitude 75, 80an d cushion pressure 81frequency response 318-19.318Heave attenuation system 335-6Heave displacement 81Heave frequency 80Heave motion 76, 76. 81, 306, 341flow modes in 77 ,7 8frequency response for 77Heave position 8 3Hcavc stability 80, 83derivatives

calculation 77-80experimental methods 80-2Heave stiffnessfor howlstern seals 328Heave velocity 8 1. 83H EB A high efficiency fan 431-2Heeling 138, 141ang le 361-2moment 361regulation using weight of persons andwater (oil) ballast 215

restoration moment 145restoring moment during 223righting a rm 147righting mo men t of howlstern seal during155with air cushion compartmentation o nrigid surface 164with air cushion compartmcntation onwaler 164without air cushion compartmentation o nwater 164High-performance marinc vehicles,classification 2High-speed marine vehicle typcs IHM-2 14-15,20, 330, 356,408bow scal 17glass reinforced structures und er

construction 16stern seal 17H M - 5 20HM-218 16HM-221 18Holland 40Horizontal a ir rudders 20 8 1 0Hovercraftaccidents 13, 13, 14classification 6futu re 45-6historical background 1 4principal particu lars for carly Chinese andBritish 7

see alro ACV: SESHovercraft D evelopment L td 10, 11, 275Hovering damping 76-83Hoverlloyd 16Hovermarine Limited 14, 18Hulldesign 185efficiency 544exte rna l forces o n 461-5strength of 464structural design 474. 476weight of 393, 397Hull-borne operation, bending mom ent 471Hu mp drag 132H u m p transition speed 364HVAC 515Hydrodynamic coel'ficients 222Hydrody namic drag 274du e to engine cooling water 115

see ulso Drag


12/20

624 IndexHydrodynamic forces and mom ents 221-2

acting o n sidewalls 285-6. 295, 303acting on skirts 294, 301-3acting on stern seal 303Hydrodynamic resistance 1, 178Hydrofoil patrol boat (PHM) 32Hydrofoils 42, 43

anti-plough-in 327Hydrostatic pressure acting on bo ttom andsidewalls 473Hyperbolic distribution 89Ice breaker 45Inducer pumps 559lnllatable diaphragm s, tenlion calculation252lti~ier raft 132, 133Inneriouter water lints 126lnncrloutcr watcr surfaccs 188Insulation 370Internal air stream lines 180Internal wave profiles 177Italy 40Japan 40J E F F ( A ) 2 5 . 1 6 4 ,2 4 1 , 4 3 6 ,4 6 3J E FF(B) 2 5 ,9 6 ,4 6 3Jct cxtcnsions 49k t velocity 498Jetted air rudd er 208Jcttcd bag typc skirt 235.Jetted extensiotis 128Jetted nozzle skirts 236Jcttcd skirt 127.Iin Snh River 5. 353K-SES 28Kaario, Toivio 3Korea 40LACV-30 26Laplace transformation 317LC AC 25-6.43. 241. 507LCAC-001 207LCG 94, 130-2, 130, 131, 185LEBED 23LHD -4 26Life-saving equipme nt. weight o f 395Lift drag 185ratio 134Lift fans 2 8 2 4

balancing 429basic da ta 427characteristics a t sm all flow rate 429impellor speed a nd diatllctcr 429installation 430, 430prcssure-llow or 296selection a nd design 420 32statistics 427tcchn ical issues 429-32Lift power 51, 54 5_ 148output coefficient 65versus air inlet loca tion 415Lift systemdesign 406-32distribution of pressure 406ducting problems 326insufficieticy 3 26layout 406powcr 412 13simulated pressure distribution 411Lining situation, strength calculation 473Limiting roll angles versus relative cushionheight 362Limiting atress design 564

Liquid load 396 7Load transporters 45Local load ing 471-2Longitudinal ccntrc of gravity; see L C GLongitudinal metacentric height 356 60Longitudinal motionin rcg~t larwavcs for ACV 308-22it 1 waves 296307

principal parameters 298Longitudinal stability kccl (LSK) 139LSD-I 26M10 44Machineryco ntro l 604-5, 604G.5space layout 606Maticeuvrability 205-31ACV 206~basic assumptions and nomenclature 218,

218. 219diflerential equations of motion 217-24fcaturcs of ACVISES 205-6key factors 205-7on ice 376rcquirzments 374-6M A R I C 3, 33-8, 56, 62, 84, 88, 102, 104-6,111. 117. 119, 125, 143,465-7


13/20

Index 62 5

Marine Design & Research Institute ofChina. xec MARlC

Marine propellersbladc pitch 529blade sections 521design 520-37efficiency 520example propeller and shaft layouts for

SES 533fbr SES 535-6installation 521K, and Ku diagrams 53Usclcction proccdurc 526 31, 528types 522Market development 17-22

Matzrials 28Mayer velocity distribution 54MCM 31-9,44

dctail dcsign and construction 3 1primary design 31

MCMH 31,40MCR (Maximum Continuous power Rating)

577Medium sized patrol SES 32MEKAT 40Metacentric height

longitudinal 356-60transverse 356-60. 3.58

Military applications 43 4Military design parameters 378Military SESiACV 32Military transport vehicles, time interval

from invention to first application YMine countermeasures 11. 30-9Mine swccpcrs 41Mixed flow pumps 558Model 711 127, 173Modcl711 3 138Model 71 1-1 33,33, 235, 236Model 711-11 34. 34,214.257.441Modcl 71 1-111 34, 34,326, 327Model 713 189, 327Model 716 36Model 71641 37.37Model 717 35, 145, 151,151, 188, 189Model 717-71 36, 356Model 717-111 356Model 717A 156. 158Model 717C 121, 130, 131, 156, 158, 159,

160, 357Model 719-11 36

Model 719 433Model 719-11 43,460Model 7202 35Model 7203 36Model 7205 199Model experiments 342-52Moment of inertia 463Momentum exchange principle diagram 496Momentum theory 97,493-8, 524, 548-55Motion pumping 274Motion standards 360Motions in waves 273-341

characteristic features of ACV and SES2768historical review 2 7 6 6

key craft paranlctcrs 278short crested waves 3 2 2 4

MTBO (Mean Time Between Ovzrhaul) 577Multi-bag stern skirt 247Multi-cell skirt system 165Multiple engines 579-81MVPP5 15,19,226MVPP15 15NACA 16 scrics 524NACA h3 series 51 9NACA 66 series 524National Rcscarch Dcvclopmcnt

Corporation 10Needham, C.H. Latimer 11.232Nct positivc suction hcad (NPSH) 544, 547,

561-2Newton's formula 53Noise

fans 430gas turbines 603lzvcls 369-72. 370, 372 4. 372water jets 539, 540

Non-flush sea-water strainers, drag of 11G17Norway 3940Nozzles 546-7

elevation 547Obstacle clearance capability 375, 376Oil exploration 22, 39Oil field applications 4 6 5Open loop and segment skirt 243, 261Operating modes 136Outline design procedure 535Ovcrdll propulsive efficiency (OPC) 538, 554,

562


14/20

626 IndexOverturning 173-85. 175. I82

and yawing angles 183at high speed 177 85at low speed 176in waves 185-6measures for improving resistance to

1835principal reasons 18&3SR.N6 186

Parabola-shaped sidewalls 114Parabolic water plancs 114Passenger accommodation 42Passcnger ferries 44Patrol vessels 40Payload factor 397Payload fraction 38493Peripheral Interfacc Module (PTM) 609Peripheraljct air cushion 50-1Peripheral jet hovercraft 48Pitch

amplitude, frequency response 319-20,319,333

angle 306damping 333 4exciting moment 307motions 340-1

Pitching 273Planing craft 1,42Planing stern seal 154Plate thickness in hull structural design 474,

476Platforming 7 3 4 , 74

analysis 7 4 6Pleasure craft 44Plenum chamber

cushion 8. 52on rigid surface 5 1-2theory 72

Plough-in 173-85, 174, 182, 325at high speed 177-85boundary 181

SR.N6 186cushion pressure during 326in following waves for SES 324-8internal reasons 326 7measures for improving resistance to183 5methods for prevcnting 327-8principal reasons 180-3progression 178-80, 179

test dala 180see a l , ~ o nti-plough-in

Position determination 220-3Post-hump spced 374Power augmented ram wing (PARWIG) craft5-9,6Power consumption

in head winds and waves 406per ton-knot 20

Power loss with increased temperature 5 8 4 5Power pcr unit seat 398Power plant

limitations 399weight of 395 6

Power transmission 564-73design criteria 564-~6

Power unit selection 577-61 1design requirements 604-6

Powering estimation 585-7, 586, 587Pressure coefficient 345, 462Prcssure-flow of lift fans 296Pressure head equation 283Pressureilength ratio 86, 87Propulsion devices, turning tracks ibr 229Propulsion system 28, 37, 37, 41, 42

design 487-576ACV 487basic theories 492-504methodology 508-9SES 488-92

PUC-22 592Puff ports 213-~14. 14, 231Pump

characteristics. types and selection 555-6eficiency 559

Quill shafts, drag due to 116Radial flow pumps 558Ram air pressure recovery 417Range determination 399Recreation design parameters 379Reduction drives 572-3Relative air gap 65Relative initial static transverse metacentric

height 148-9.148, 149,150Relative sidewall thickness 1489, 148Relative transvcrse righting arm 150Remote monitoring 604-5, 604-5Residual drag 84-5

coellicient of sidewall 115


15/20

Index 6 27Restoring moment during heeling 223Retractable water rudder 210. 210Reversing gcar 562-3Reynolds law 342Reynolds number 100, 104, 344,345,349Ride characteristics 367Ride control system (RCS) 30, 336, 336, 337Ridz quality 43Righting moment of howlstern seal duringheeling 155Rigid body dynamics 277Rigid bow seal l35Role naramcters 378-9Roll amplitude, frequency response curves

for 293Rolling 273, 280, 285stiNness 359Rolling angle and craft speed 178Rolls-Royce 'Marine Proleus' gas turbineenglnes 13Rotatable nozzles 562Rotating ducted thrusters 213Rotating thruster unit 508Rotation derivatives 220-3Rudders 208-1 1drag of 115-16Running attitude 156 9, 158Safety factors 4734. 474, 475Saunders-Roe Limited 10, 11Scaling criteria 351during static hovering tests 343-8over water 348-52Scaling laws 342-52Sea Action Group (SAG) 44Seakeeping quality 43Seal drag 121coefficient 103Seasickness 368Seaspeed 16Seaworthiness 90, 273-4, 321, 32841,454effcct of principal dimensions 33&3key observations 33941requirements 3645, 399scaling conditions 352Service speeds 43SESapplications 41-5dynamic transverse righting moment of159location of inlets and appendages 188-90

plough-in in following waves for 32 6 8static transverse stability on cushion13 7 52transverse dynamic stability 152 63water surcace deformation inlbeyond aircushion on calm water 197-200, 198SES-100 86SES-100A 27,27,28, 30, 85,85. 175, 337SES-100B 27, 28SES-200 30, 30, 39, 86, 336, 336Shafts and boss, drag due to 116Shallow watcr drag 91Shanghai Hu Ilong Shipyard 35Shaw, R.A. 10Shear forces 471Sidewail 109air leakage 280, 281-2chines 335configurations 66depth 333depth ratio 400draft 280, 281-2geometric configuration 145-8hydrodynamic forces and moments acting

on 285-6, 295,303inner draft 333thickness 66, 357thickness ratio 332-3, 40 2 4wetted surface of 110Sidewall hovercraft 4, 5development in UK 9 22Sidcwall water friction drag 104-10B.A. Kolezaev method 109MARIC method 104-6mcthod used in Japan 106-8, 108NPL method 109Sidewall wave-making drag l 11-14, 113B.A. Kolezaev method 114equivalent cushion beam method 11 1-13Hiroomi Ozawa method 113-14Single wall theory 52-5Skirtabrasion and corrosion 434abrasion force 441air feed holes 449-50assembly and manufacturing technology449 51attachments 449bounce analysis 267-70,268,269,270clearance 79, 82, 171coating 439, 44 65, 44 4


16/20

628 Index

Skirt (contd)cumponcnts, force acting on 264contact drag 277-8damage patterns 433 4deformability 455deformation 242delamination 4334 , 438drag ibrcc 44 1dynamic response 271-2effect on seaworthincss 328 30Ihilurc modes 435-6, 435gcometric features 451. 452ground interference drag 124hydrodynamic foi-ces acting on 294, 301-3impact force 442manufacture flow chart 450observation under water 238pressure drag 10 1-2processing 450service l ik 433shifting installation 215shifting system 165stiKness 455systcni 184tailoring 449-50tearing 434tcst boxes 343test rig 568 , 5&9. 59. 60total drag 99luck-in at bow skirt 326tuck-under 261-7tuck-under boundary 453type cffcct on seaworthiness 329-30wave-making drag coellicicnt 101weight 265-7, 396weight pcr unit area 346, 349-50with extended flexible nozzle 236

Skirt analysis 232. 452-7forccs acting on 262-3forces analysis for deformed fingcrs 266hydrodynamic forccs acting on skirts

running on water 265Skirt bag

D-type 184, 184tension acting on curved sections 262

Skirt configuration 53, 134, 165, 233, 233,242-5,244,245, 249.250amphibious ACV 235 42BH.7 241design 451-7development 235 49

evolution 235SR N 6 241state of the art 23549

Skirt design 232, 433~57main issues 234

Skirt drag 98-103, 124Skirl drag coefficient 134Skirt fingers 436, 439, 441, 442, 442. 445. 450

inward inclination angle 454Skirt force (morncnt) 284Skirt friction drag 99-101Skirt geometry 453

design 323clastic deformation and hysteresis etTect

250-1Skirt height 328-9, 359

and cushion beam ratio 358ratio 400-1statistics 356

Skirt joints, selection 447-9, 447, 448Skirt lift apparatus 214-15. 215Skirt loading 437-41, 437

prcssure force 437vibration forces 437

Skirt material 64, 64, 347open wcavc cloth 443selection 442-7specific weight 44.5, 446tension and tear strength 443test facilities 440thickness effect 330

Skirtiterrain intcraction drag 121-3SKMR-I 25,463Slamming 1. 46G7

forces in wavcs 364-5Slipstream jet velocity 497Small waterplane thin hull vcsscls (SWATH) 1S-N curve 569.570Speed

degradation 330, 331, 341, 364delerrnination 399improvement 332

Spray suppression skirts 270-1, 272, 456 7SK.N1 7.7. 10. 11,48-9, 507SR.N2 11 , 13SR.N3 11, 12, 13SK.N4 11. 12, 13. 14, 16, 17, 239, 330, 330,

331, 331. 333, 361, 368, 418, 441, 463,520drag and thrust curves 119skirt configuration 240


17/20

Index 629SR.N5 13,76, 173SR.N6 13, 14.15, 86, 173, 174. 176, 214,361,

418overturning 186plougli-in boundary 186

SR.N6-012 185Stability 135 86

acceptable 137and cushion height

ACV 355SES 356

coordinate system of craft l67criteria and standards for stability of SES

stability in turns 162stability in wavcs 162static stability 161-2

damagc requirements 363design requirements 355 62dynamic stability of ACV travelling ovcr

watcr 173effect of fan flow rate on transverse

stability 01- ACV 172eflect of stability skirt clearancc on

transverse stability 171effect of various parameters on transvcrseslability 14&51in waves 364internal stability skirts 190longitudiiial stability trunks 456rcquirements 399

for large hecling angles 361-2skirt configurations 261standards 355-62static transversc i~llt ial tahility of ACV

360static transverse stability of ACV l69static transversc stability on cushion

137-52; 143static transverse stability without LSK

141-2transversc dynaiilic stability 152-63transverse stability 358

as function ol' Froude number 177during lake-off 159-61effcct of VCG 171-2factors affecting ACV 168-72for ACV 163-8in waves 161on cushion in motion 154 9with flexible bowlstern seals 154-5with rigid stern seal 155-6

without cushion compartmentation170-1

transverse stability moment of hcclcd SESal spccd 160

transverse stability trunks 456Standing's formula 197Static air cushion characteristics on water

surface 66-71Static air cushion performance of ACVs on

water surfilcc 68-71, 68, 69Slatic hovering performancc of SES on water

66-8Static hovcriiig tests 343-8Static thiust 5 0 14Stator systems, design 518Steel 459Stern bag skirts, geometric parameters 259Stern double planing bag 247Stern planing rigid seal 247. 249Stern scal 12S-9. 154

hydrodynamic forcc acting on 303with air bag 248,248

Stern skirt, pressure distribution acting oninner surface 260

Streamlineanalysis 60-2diagram 61

Strength calculation 461Strength of hull 464Strouhal number 346Structural design 458-86

ACV 459 60current state 460features 458-60hull 474, 476SES 459

Structural strengthanalysis. former IJSSK 467-73calculation 465-7

Strut palms, drag of 116Subcavitating propellers 520. 526Subsystem design 354-5Supercavitating propcllers 522, 531-7

outline dcsign procedure 535Supports 571Surface contact propulsion 57 66design considerations 574-6Surhcc cffect ships (SES) ISway 273Swivelling pylons 211, 212Systems 28


18/20

630 IndexTacoma Marine Industries 40Take-off 1249, 159-61dynamic stability during 127holes 71

performance 72water contact phenomenon of how sealduring 105TCG 162Teeth 271Thornycroft. Sir John 1. 2Thrustdeduction 544in head seas 338Thrustllift ratio 181Torsion 469Torsion load 470, 470Torsional stress 564Total drag 85of ACV model 71 1-IIA 118of ACV model 7202 118over water 1 17-21ACV 117-19, 117,118SES 119 21skirt 99Total system weight 577-9, 578Transmission configuration 582~4Transmission shaftdesign factors 566design load case matrix 568design stresses 566-8fatigue endurance of 569-71sections for analysis 567Transport eficiency 397Transverse metacentric height 162, 356-60.

158Transverse motions of SES in beam seas279-94Transverse righting moment 160,295Transverse roll stiffness versus cushionheightlwidth ratio 360Transverse shift of ccntrc of cushion area165-6, 165,166Trim 187-204angle 181, 182. 185calculation 153 4

factors influencing 188prediction above hump speed on calmwater 203-4regulation using weight of persons andwater (oil) ballast 215TSL-A 600.601

Tuck-under 267Turning diameter 374Turning pcrformancc 227 31Turning tracksbetween bank and non bank turn 230for propulsion devices 229Twin bag skirt 154, 451

UH-15P 502UK 9 21 ,4 0Underwater appendage drag 115-17US 25-32amphibious craft 25surface effect ship development 26-30USSR (formcr) 22-5,22-3Utility applications 44Utility craft 45, 590Utility design parameters 378-9VA.1 to 3 series 11Variable depth sonar (VDS) 32Variable-pitch ducted fans 516Variable-pitch propeller hub constructionand controlsystem 514VCG171 2Velocitv streamlines 501. 502Vertical acceleration 320, 335. 336. 365-8,366,367Vertical fins for course stability 208, 209Vertical rudder 208, 209Vessel trim 604Vibration 28, 31, 368, 47686absorption 478-82acceptahle levels 480analysis 479

assessment 485critical operational frequencies 484damping 370-2design 481detail design phase 4 8 3 ~ 5diesel engines 596 5during construction 485exciting force 482high operational speed 477TSO 2372 and IS 0 3945 standards 4 7 ~low natural frequency 476malfunctions caused by 477permissible rules 482preliminary design phase 482-3severe and supcrharmonic excitationsource 476


19/20

Index 631

tests and trials 486watcr jets 540

Vickers 12Vortex theory 524 6Viya,ycur 96VT.2 14, 15Waban Aki 45Wake factors 544Warner, D.K. 3Watcr contact plienomcnon of bow seal

during take-off 105Water jets 537 64

advantages 538cavitat~on 56-7efficiency 492,521, 522, 548 54,549,551,

557flush-type inlet 538geometries 541inlet losses 544 6inlet velocity 560-1inlet with sccondary slow specd intake 546integrated control systems 5 6 3 4KaMcWa 522noise 539, 540overall propulsivc cficiency (OPC) 538,

554, 562performancc 540-1physical dimensions 540prcssure effects around intake 553selection 543, 550, 559-62steering 562 3tlirusl vs. craft speed 558vibration 540weight vs. inlet diameter 562, 563

Watcr propulsor types 491Water surfacc deformation 189, 192

at inboard profile 194HD-2 194inlbcyond ACV air cushion over calnl

water 190 6iniheyond SES air cushion on calm water

197-200. 198Water surface profile 192Wavc amplitude 19 6 7Wave equation 298-9, 312Wave exciting force, frequency response ibr

320Wave exciting moment, frequency response

for 320Wave height 338,340

Wave impactforce distribution 472-3loading coefficient 462presrul-e 463-5,464

Wave interference 323Wave-making drag 86-93, 90, 91.92, 94, 94,

97coefficient 88, 8 9 , 9 6 5coeflicient of slender sidcwalls 114influence of water depth 92ratio 91

Wave-making drag-lift ratio 89Wave profilc

and Froude number 189bcyond cushion, 1ilodel7205 199inloff cushion due to moving rectangular

air cushion 193Wave pumping 274, 278

concept 49,73-6motion 74. 74rate 75-6

WD-901 37.37, 3 8 , 189WD-902 38Wcapon systems 32, 42Weber number 100, 349Weight

components 379 80distribution 38.5. 388equilibrium equation 142of ACV 389~90,403of air propellers 51 3of deck equipment and painting 39 3 4of electrical equipment 396of equipment 394of fuel and oil 396of hull 393, 397of life-saving equipment 395of mctallic structure 393of power plant 395-6o f ship systems 395of skirt systcm 265-7, 346. 349 50, 396of water-jet unit 562, 563vs, displacement 394

Weight classilicationformer USSR 381-2high-speed boats 382 4MARIC 380USSR 381Western countries 382

Weight estimate 379-84checklist 391-2


20/20

6 3 2 IndexWest, A A . 52-5, 63 Wing in ground ell'cct machines (WIG andWcstland AircraSt Limited 1 1 PAKWIC;) I . 5 9 . 6Wetted surlhcc Work boats 45

corrzction coefficierlt o l 109of sidewalls 104. 106. 107, 110 XR-I 138

Wetted hurlhcc area, correction coefficient XR-IA 26 , 26107, 108 XR- D 30Wetted surface5 188 XR-S 29Whirl speed 568 9Wind direction and speed 228 Yaw 92. 9 6 5 . 273Wind tunnel model lcsts 347 Yawing angles and overturning 183Wind tunnel tcsts 343

Air Cushion

Documents

Transcript of Air Cushion