FIFTY YEARS & MORE OF HOVERCRAFT DEVELOPMENT

SNAME and IHS Dinner Meeting

11 MAY 2011

DAVID R. LAVIS

BAND LAVIS DIVISION OF CDI MARINE

CONTENTS OF PRESENTATION

EARLY ENDEAVORS RAPID EXPANSION

MAJOR CHALLENGES MOST SIGNIFICANT CONTRIBUTIONS MANY ACV & SES PHOTOS & VIDEOS

RECENT DEVELOPMENTS CUSHION SEALS PROPULSION MANEUVERING CONTROL DESIGN SOFTWARE

SUMMARY, CONCLUSIONS & THE WAY AHEAD

EARLY ENDEAVORS1936 – Grandpa Lavis stumbles onto

the idea of Amphibious Assault

WELL, MY GRANDPA DID RUN A BOAT BUILDING BUSINESS

EARLY ENDEAVORS

RINA PAPER LISTS 30INVENTORS WITH PATENTS PRIOR TO 1953.

AT LEAST 12 OTHERS DIDNOT FILE PATENTS.

8 PATENTS FEATURED FLEXIBLE SKIRTS BEFORE SR-N1 CROSSED THE ENGLISH CHANNEL WITHOUT A SKIRT IN 1959.

SR-N1 in 1959

Date of Patent

Name and Location Subject

1716 Swedenborg, E., Sweden Plenum Craft Illustration

1876 Ward, J., San Francisco, USA

Plenum Machine Idea

1877 Sir John Thornycroft, UK Air Lubricated Hull

1880 Girard, L., France Rail Car

1882 De Laval, G., Sweden Air Lubricated Hull

1888 Walker, J., Texas, USA Air Lubricated Hull Idea

1889 Barre, M.C.A., France Rail Car

1897 Culbertson, USA Sidewall Craft Idea

1902 Therye, C., France Rail Car

1906 Schroeder, F.W., Germany (British Patent)

Air Lubricated Hull Design

1907 Clark, J., USA Craft With Annular Ducts

1908 Worthington, C., USA Rail Car With Flexible Seals

1908 Porter, J.R., UK Annular Jet Craft With Flexible Skirt

1909 Wunderlich, A., Germany Plenum Craft

1912 Alcock, A.U., Perth, Australia

Levapad Craft

1913 Eells, A.F., USA Rail Car

1916 Von Thomamhul, D.M., Austria

Air Lubricated Torpedo Boat

1921 Gambin, M.A., France Sidewall Craft

1922 Breguet, L., Paris, France Plenum Craft With Flexible Seals

1922 Trask, F.G., North Dakota, USA

Rail Car

1925 Casey, V.F., Minneapolis, USA

Air Lubricated Hull With Air Recirculation

1927 Tsiolkovski, K.E., Russia Rail Car

1928 Nicin, V., Dresden, Germany

Plenum Car Giving Reduced Wheel Load

1928 Warner, D.K., Sarasota, USA

Sidewall Craft with Spring-Loaded Rigid Seals

1935 Birrard, J., France Sidewall Craft Design

1935 Kaario, T.J., Finland Plenum/Ram Wing Craft

Date of Patent

Name and Location Subject

1939 Courant, France Sidewall Craft with Mechanical End Seals

1942 Cristadoro, C.C., Venice, CA, USA

Sidewall Craft With Flexible End Seals

1944 Brian, W.S. & Birk, F.J., Owensboro, KY, USA

Sidewall Craft

1952 Bondat, A.J., France Snow Skis With Multi-Plenum Air Cushions

1954 Seck, W.G., Canton, Ohio, USA

Hovering Vacuum Cleaner by Hoover Co.

1955 De Lima, R.A., Brazil Peripheral Jet and Aircraft Landing Gear

1955 Cockerell, C., UK Peripheral Jet and Sidewall Craft

1955 Roe, A.V., Canada Peripheral Jet Craft

1957 Beardsley, M.W., Severna Park, MD, USA

Craft With Peripheral Jet & Membrane Sheet

1957 Weiland, C., Switzerland Craft With Labyrinth Seal

1957 Bertin, M., France Craft With Multi-Cell Plenum Skirt

1958 Jay, D.J. & Pelthman, H.W., USA

Craft With Multi-Plenum

1958 Latimer, C.H., Needham, UK

Craft With Flexible Skirt

1958 Petersen, T.K. & Smith, P.L., Tulsa, OK, USA

Cargo Handling Conveyor

1959 Gaska, C.W., Michigan, USA

Craft With Flexible Skirt

1959 Vaughen, J.F., Irving, Texas, USA

Hover Pallet With Flexible Seals

1960 Ford, A., USA High-Speed Sidewall SES

1960 Hurley, R.T. & Agni, E.S., USA

Sidewall Craft

1960 Mackie, H.A. & Veryzer, R.W., USA

Wheel Barrow With Flexible Skirt

1960 McCreary, N.B., Arkansas, USA

Plenum Craft With Flexible Skirt

1962 Lewis, N.W., USA Craft With Finger Skirt - Vertical

1962 Bliss, D.S., of HDL, UK Craft With Finger Skirt - Inclined

CRAFT WITH FLEXIBLE SKIRT BY PORTER, UK, 1908

FABRICSKIRT

FLEXIBLE END SEALS BY BREGUET, FRANCE, 1922

FLEXIBLE END SEALS AND CUSHION DIVIDER BY CRISTADORO, USA, 1942

Transverse Seal

Air Supply Fans

AVRO PROJECT-Y, FLYING SAUCER (1952 to 1962, CANADA)

Click for web source Click for web source

CURTIS-WRIGHT MODEL 2500 AIR CAR (USA)Operated in 1959 with 8-inch Flexible Skirt

Click for Web Source

EARLY ENDEAVORS (Contd.)

1952 – 1960 ACV (GEM) DEVELOPMENT CANADA (AV ROE); UK (Cockerell), USA (CURTIS-WRIGHT, GM,

FORD, CONVAIR, MARTIN, BELL, GD, H. Chaplin, Beardsley, Bertelsen)

1960 – HIGH-SPEED SES DEVELOPMENT USA NADC (A. Ford) & UK HDL (Cockerell)

1960 – 1970 RAPID EXPANSION UK, USA, CANADA, SWEDEN, NORWAY, FRANCE, JAPAN,

RUSSIA, CHINA, AUSTRALIA

TECHNOLOGY PROGRESSION

1959 UK UK

1963 USA

1980 USA 2004 FINLAND

THE PRINCIPAL CHALLENGES

HIGH COST (LOW EFFICIENCY) PROPULSION LOW RELIABILITY OF HIGH-POWERED SYSTEMS NEED TO REDUCE AIRBORNE NOISE PERFORMANCE SENSITIVE TO WEIGHT GROWTH

TWO ADDITIONAL SYSTEMS (SKIRTS + AIR SUPPLY) SKIRT MAINTENANCE (MINIMIZED BY GOOD DESIGN)

SPEED LOSS IN A SEAWAY CHALLENGING MANEUVERABILITY

SAFETY (HIGH-SPEED NAVIGATION)

Aerojet All-Welded Aluminum AALC JEFF(A) (ACV & SES) – 1977 Bell AALC JEFF(B) Controllable Bow Thrusters (ACV) – 1977

SRN-Series Integrated Lift & Propulsion (ACV & SES) – 1962 SRN-Series Integrated Maneuvering Controls (ACV) – 1962 US Navy XR-Series of Experimental SES – 1962-85 Bell Skimmer Shrouded Propellers (ACV) – 1964 Aerojet General Application of Water Jet Propulsion (SES) – 1966 Aerojet General Ride Control (SES) – 1966 Aerojet 100A, Bell 100B and Rohr 3KSES Programs – 1967-79 Hovermarine GRP Hull Mass Production (SES) – 1968

SOME OF THE MOST SIGNIFICANT DEVELOPMENTS1962 to 1977

HDL Bag-Finger Skirt (ACV & SES) – 1962 Denny D-2 GRP Hulls (SES) – 1962 Airscrew-Weyroc Centrifugal Fans (ACV & SES) – 1962

BHC/HW Air-Cooled Diesel, Auto-Welded Structure for AP.1-88 (ACV) – 1982 Griffon Hovercraft Ltd starts World’s Largest Range of ACVs – 1982 LCAC Erosion Protected Propeller and Fan Blades (ACV) – 1984 Brodrene Aa Cored Composite Structures (SES) – 1986 BLA Compact Axial-Flow Water Jets (SES) – 1988 ABS Hovercraft Ltd M-10 with Advanced Composites (ACV) – 1994 BLA Deep Skirt (ACV) – 1995 BLA Wake-Adapted Shrouded Airscrews (ACV) – 2003 Japan’s Ogasawara 460-ft Techno-Superliner (SES) – 2005 Russia’s Murena E-Class Landing Craft (ACV) – 2005 IMAA Partial Air Cushion Catamaran, PACSCAT (SES) – 2008

SOME OF THE MOST SIGNIFICANT DEVELOPMENTS1978 to 2008

BHC Low-Pressure Responsive Skirts (ACV) – 1978Bell BH-110 Medium Displacement Sidehulls (SES) – 1978 BLA Whole-Craft Design Synthesis Tools (ACV & SES) – 1978

VA1, 1960 (UK)

CC 1 AND 2, 1960 & 1961 (UK)

CC 2, 1961 (UK)

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SR-N2, 1961 (UK)First Integrated Lift & Propulsion & Maneuvering Control System

VICKERS VA-2, 1961 (UK)

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VA3, 1962 (UK)First ACV Passenger Ferry

SR-N3, 1963 (UK)

BELL SKMR-1, 1963 (USA)First ACV with Shrouded Props

BELL SKMR-1 (USA)

HD1, 1963 (UK) With Inclined Finger Skirt

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SR-N6 AND SR-N5, 1965 & 1964 (UK)

SR-N5, 1964 (UK)With Peripheral Jet Skirt

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BHC SR-N4, 1968 (UK)With Bag-Finger Skirt

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BHC SR-N4, 1968 (UK)

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BHC BH-7, 1969 (UK)

BELL LACV-30, 1969 (USA/CANADA)Modular Construction for Transportability

JEFF(A), 1977 (USA)First ACV with Welded Aluminum Structure

JEFF(B), 1977 (USA)First ACV with Rotatable Bow Thrusters

BHC AP-188, 1982 (UK) Air-Cooled Diesel-Powered and Auto-Welded Aluminum Structure

LCAC, 1984 (USA)

GRIFFON-HOVERWORK 4000 TD (UK)

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POMORNIK, 1986 (ZUBR-CLASS USSR)

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ABS M-10, 1994 (UK)

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DASH 400, 1998 (UK)

DENNY D1 SES, 1961 (UK)

DENNY D2 SES, 1962 (UK)First SES Passenger Ferry and First of GRP

HD1 CONVERTED TO SES, 1963 (UK)

US NAVY XR-1 SES, 1963 (USA)First High-Speed SES

US NAVY XR-1D SES, 1974 (USA)

US NAVY XR-3 SES, 1967 (USA)

HM2 SES, 1968 (UK)

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HM2

BELL SES 100B, 1972

AEROJET SES 100A, 1972 (USA)

3KSES (USA)

US NAVY XR-5 SES, 1973 (USA)

BELL-HALTER BH-110 SES, 1978 (USA)First Commercial SES in USA

SES-200, 1982 (USA)

CIRR 120P SES, 1987 (NORWAY)First Cored FRP SES

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DERGACH SES, 1987 (USSR)Largest Military SES

CORSAIR SES,1989 (GERMANY) Modular Construction including MTU Diesels

Suspended in Modules from the Overhead

AGNES 200 SES, 1990 (FRANCE)

AGNES 200 SES, 1990 (FRANCE)

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SMYGE SES, 1991 (SWEDEN)

OKSOY & ALTA-CLASS, 1993 (NORWAY)Mine Hunters and Sweepers

OKSOY SES, 1993 (NORWAY)

P960 SES, 1997 (NORWAY) 55-knot Skjold Military Patrol SES

IMAA 1/3rd -Scale FLC Manned Model (UK) Partial Air Cushion Catamaran, PACSCAT (SES)Operating at High Speed in Scale SS4 Head Seas

PACSCAT 2010 (UK)

Click for Web Source

JAPAN’S TSL-A140 OGASAWARA SES, 2005Largest Fast Ferry of any kind

MORE RECENT TECHNOLOGY DEVELOPMENTS

CUSHION SEALS PROPULSION MANEUVERING CONTROL DESIGN SOFTWARE

SKIRT SYSTEMSCross-Section of JEFF Craft Skirts

SIDE SKIRT BOW SKIRT

DEEP SKIRT DESIGN

DEEP SKIRT DESIGNSubjected to Extensive Sub-Scale Test Prior to Committing to

Full-Scale Prototyping

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NOT ALL IS GOODMaterial Delamination after 100 operating hours on the prototype skirt.

Issue also showed up on the Canadian Coast Guard AP.1-88/400 and the Hoverspeed SR.N4 MKIII.

All three craft used the same natural rubber material.

Suspected that Fatigue was the Primary Failure Mode.

NOT ALL IS GOODFEA analysis of an inflated finger indicated Stress Concentrations and areas of Large Deformations.

Stress Map Deflection Map

THINGS GET BETTERFEA analysis indicated that a modification of the Design & Lofting Process would correct this.

Deflection Map before Modification

Deflection Map after Modification

SECOND & THIRD GENERATION DESIGNS

2nd Generation T-2000 Skirt had 440+ hours on original bow and side fingers.

Stern corner and stern fingers replaced after approximately 300 hours.

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SECOND & THIRD GENERATION DESIGNS

Believe that Additional Performance Improvements are Possible

.

Head-Sea Operation in Sea-State 3

THE OVERALL POWERING CHALLENGEDiminishing Transport Efficiency with Speed

0.1

1.0

10.0

100.0

1,000.0

0.1 1.0 10.0 100.0Speed (Volumetric Froude Number)

Monohull

Catamaran

SWATH

Hydrofoil-Foil

SES

ACV

HydroPlane

Miss BudweiserHydroPlane

JGH

RV Triton Trimaran

InCat 050 HSV-X1

InCat Jervis Bay

Jetfo il Hydrofo il

VISBY MonoHull

Bazan B60 Cat

KNM Skjold SES

Aker T2000 ACVStena HSS 1500 SemiSWATH

Aus tal III MEF Cat

IOWA Monohull

Offs hore Racer Monohull

THE POWERINGTHE POWERING

CHALLENGECHALLENGE

W.V P

SPEED (VOLUMETRIC FROUDE NUMBER)

Circle Q

Circle K

TODAY’S SOLUTIONS

0.1

1.0

10.0

100.0

1,000.0

0.1 1.0 10.0 100.0Speed (Volumetric Froude Number)

WVP

Monohull

Catamaran

SWATH

Hydrofoil-Foil

SES

ACV

HydroPlane

Miss BudweiserHydroPlane

JGH

RV Triton Trimaran

InCat 050 HSV-X1

InCat Jervis Bay

Jetfo il Hydrofoil

VISBY MonoHull

Bazan B60 Cat

KNM Skjold SES

Aker T2000 ACVStena HSS 1500 SemiSWATH

Aus tal III MEF Cat

IOWA Monohull

Offs hore Racer Monohull

70-kt ACV

40-kt SEMI-SWATH40-kt SEMI-SWATH

70-kt ACV

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55-kt

SES

100-kt OFFSHORE RACERS

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170++-kt HYDROPLANES

DUCTED PROPULSORS

Typically, designs are developed for free-stream conditions. Ignores Installation

Effects. Full-scale trials

experience indicates that these designs typically produce Significantly Less Thrust than expected.

TOOL VERIFICATION

LCAC propulsor analyzed prior to starting new design.

Checked against known performance.

Results compared favorably.

LCAC CFX Computational Model

CFX for LCAC at 25 knots (Midway Station 7’6”)

AIR FLOW INTO PROPULSOR

View from Bow View from Aft

Leading Edge of Shroud

BOW THRUSTER NOZZLES Bow Thrusters are used on many modern ACV’s

Enhance Maneuverability Augment Thrust from Main Propulsors Provide Some Redundancy to Main Propulsors

BOW THRUSTER NOZZLES

Typical Bow Thruster Nozzle Easy to Manufacture Aerodynamically

Inefficient Easy Bend versus

Hard Bend Large Over-Turning

Moment on Bearing

BOW THRUSTER NOZZLES

Aerodynamically Efficient Cascade

Significant Reduction in “Over-Turning” Moment on Bearing

Reduced Visual & Radar Signature

Complex to Manufacture

Low-Profile Bow Thruster

Full-Scale Trials Verified Aerodynamic Efficiency

ACV DESIGN TOOLDesigning With Respect to Cost

SUMMARY & THE WAY AHEAD NEW SKIRT

Lower drag, reduced powering, more reliable, less cost. Extra depth, improved seakeeping /overland operations.

NEW LIFT FANS Higher efficiency, more compact & quieter.

NEW PROPULSORS Higher power absorption, more efficient.

NEW BOW THRUSTERS More efficient, less vulnerable, reduced loading.

NEW SES Lower cost, more reliable PACSCAT solution.

ACV & SES DESIGN & ASSESSMENT TOOL Reduced cost, easier to assess technology options. Easier to assess cost impact of operational requirements.

WHAT’S LEFT Lighter weight systems, better skirt material, stability, ride,

collision avoidance, less noise, improved RMA & lower cost.

Questions?