US3512603A - Flexible hulls - Google Patents

Flexible hulls Download PDF

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Publication number
US3512603A
US3512603A US730857A US3512603DA US3512603A US 3512603 A US3512603 A US 3512603A US 730857 A US730857 A US 730857A US 3512603D A US3512603D A US 3512603DA US 3512603 A US3512603 A US 3512603A
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US
United States
Prior art keywords
flexible
cushion
vehicle
pressure
skirt assembly
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US730857A
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English (en)
Inventor
Peter Rowland Crewe
Michael Ivan Manning
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British Hovercraft Corp Ltd
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British Hovercraft Corp Ltd
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Publication date
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Publication of US3512603A publication Critical patent/US3512603A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60V—AIR-CUSHION VEHICLES
    • B60V1/00—Air-cushion
    • B60V1/04—Air-cushion wherein the cushion is contained at least in part by walls
    • B60V1/043—Air-cushion wherein the cushion is contained at least in part by walls the walls being flexible
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60V—AIR-CUSHION VEHICLES
    • B60V1/00—Air-cushion
    • B60V1/16—Flexible skirts

Definitions

  • An air cushion vehicle has a flexible skirt assembly forming at least part of the cushion barrier.
  • the skirt assembly includes an upper, inflatable flexible chamber and depending therefrom a plurality of juxtaposed discrete flexible segments.
  • the skirt assembly has characteristics such that it has suflicient strength to withstand the outward forces generated by the cushion pressure, and vibration is reduced.
  • This invention relates to flexible skirt assemblies for air cushion vehicles. It is principally, but not exclusively, concerned with skirt assemblies in which a pressurised flexible chamber acts as part of the skirt assembly, and may also provide buoyancy and keel effect when the vehicle is acting as a displacement watercraft.
  • Flexible skirt assemblies may include an upper pressurised baglike member having a plurality of juxtaposed discrete flexible segments depending therefrom, and the upper pressurised baglike member may be divided into compartments pressurised to superatmospheric pressure.
  • the skirt assembly must have suflicient strength to withstand the outward forces generated by the pressurised fluid cushion or cushions. This strength, in the type of skirt assembly hereinbefore described, is dependent, in part, upon the skirt height, the distance between its inner and outer attachment points to the rigid structure of the vehicle and the pressure within the upper pressurised baglike member. There are, however, other factors to be considered in the design and construction of such a flexible skirt assembly, for example, the resonance frequency of the assembly and the water impact loads which it receives.
  • the skirt assembly Because of the elasticity of pressurised air and the flexibility of the pressurised baglike member the skirt assembly has a natural vibratory period and if this period coincides with that of the vehicle as a whole the skirt may vibrate continually and reduce the performance of the vehicle.
  • the likelihood of skirt vibration may be reduced by changing the distance between the skirt fixing points in relation to the skirt height, by changing the pressure in the baglike member in relation to the cushion pressure or by a combination of both changes.
  • a flexible skirt assembly for a vehicle which, during at least one phase of operation, receives support from at least one cushion of pressurised fluid, the skirt assembly forming at least part of a barrier to the cushion or cushions and including at least one upper, inflatable, flexible chamber and a plurality of juxtaposed, discrete, flexible segments depending from the upper chamber or chambers, wherein the upper, inflatable, flexible chamber or chambers is inflated by pressurised fluid to a pressure between 1.15 and 5 times the pressure of the cushion or cushions.
  • a flexible skirt assembly for a vehicle which, during at least one phase of operation, receives support from at least one cushion of pressurised fluid the skirt assembly forming at least part of a barrier to the cushion or cushions and including at least one upper, inflatable, flexible chamber and a plurality of juxtaposed, discrete, flexible segments depending from the upper chamber or chambers, the upper, inflatable, flexible chamber including a sheet of flexible impermeable material attached at first and second points to structure carried by the vehicle to form a loop in a substantially vertical cross section, wherein the distance between the first and second points of attachment of the sheet is greater than 0.9 times the vertical distance between the underside of the rigid structure of the vehicle and the lower tip of the flexible skirt assembly and the pressure within the inflatable, flexible chamber is at least 1.15 times the cushion pressure.
  • the pressure in the inflatable, flexible chamber may be selectively variable within the 1.15-5 range.
  • the upper, inflatable, flexible chamber may include separate compartments at different peripheral locations around the vehicle and the pressures in each compartment may be different.
  • any combination of compartments may be interconnected and each set of interconnected compartments may have pressures different from other sets.
  • Both the upper, inflatable, flexible chamber and the fluid cushion or cushions may be pressurised with air and the supply means for the upper, inflatable, flexible chamber may be separate from the supply means for the fluid cushion or cushions.
  • each compartment of the upper, inflatable, flexible chamber may be varied by the provision of an accumulator having a variable volume interconnected with each compartment, and the accumulator may be selectively operable.
  • the height of the discrete, flexible segments in relation to the total height of the flexible skirt assembly, and also the area of the fluid cushion, may be selectively varied by changing the ratio between the pressure in the inflatable, flexible chamber and the cushion pressure.
  • the flexible skirt assembly as hereinbefore described may form the complete lateral barrier to the fluid cushion or it may be used at the bow and side portions of a fluid cushion supported vehicle only. In the latter case a simple inflatable chamber or other suitable barrier means may complete the lateral fluid cushion barrier.
  • the pressurised compartments at the sides of the vehicle may provide buoyant support for the vehicle in the displacement role, and the portions of the skirt assembly at the bow and stern may be depressurised and retracted so that the vehicle assumes the form of a catamaran displacement craft.
  • FIG. 1 is a side elevation of a vehicle incorporating a flexible skirt assembly according to the invention
  • FIG. 2 is a bow view of the vehicle illustrated in FIG. 1, on a different scale, in the air cushion supported role.
  • the left side of the figure is a front elevation of the vehicle and the right side is a section on the line IIII of FIG. 1, and
  • FIG. 3 is a diagrammatic section, in a vertical plane, of the skirt assembly of the vehicle illustrating how the ratio of the height of the discrete segments to the total height of the skirt assembly and also the cushion area may be varied.
  • An upper inflatable, flexible chamber 1 depends from the periphery of the rigid structure 2 of a vehicle and a plurality of discrete flexible segments 3 depend from the inflatable, flexible chamber 1.
  • the upper, inflatable, flexible chamber 1 includes a sheet of flexible impermeable material attached at a point 4 to the lower surface of the rigid structure 2 of the vehicle and at a point 5 carried by rigid struts.
  • the chamber 1 is inflated with pressurised air so that the sheet takes the form of a loop between the attachment points 4 and 5. This loop is provided with releasable attachment means for the segments 3.
  • the chamber 1 is divided into separate airtight compartments 7 by flexible im ermeable diaphragms 6. Interconnected With each compartment 7 is a variable volume air accumulator 8, which provides a selectively increased volume for each compartment 7.
  • Each accumulator 8 consists of a rigid upper rectangular member 9 hinged to the rigid structure of the vehicle at points 10 and flexible impermeable sheets 11 interconnecting the free edges of the member 9 and the rigid part of the vehicle.
  • the sheets 11 are restrained by internal tension members so that they assume a convoluted shape.
  • the position of the rigid member 9 about its hinge points 10 is controlled by any suitable method, for example, cables in tension, to achieve a required rate of variation of internal pressure with volume for a compartment 7 of the inflatable, flexible chamber 1.
  • Each compartment 7, together with its associated accumulator 8 is supplied with pressurised air from a source separate from the air cushion supply, and the ratio between the air pressure in the compartments 7 and in the air cushion space 12 is arranged to be within the range 1.15 to 5.0.
  • Means for generating and distributing pressurised air to the compartments 7 and means for controlling the pressure of the air so that it remains at a constant pressure with respect to the air cushion pressure are well known in fluid mechanics, and are usually incorporated in the air supply arrangements. Therefore, such means are not described herein.
  • the air cushion is supplied by pressurised air from a lift fan (not shown), and flows through ducts, as indicated by the arrow 13, to the air cushion space 12.
  • the pressurised air may be led, through flexible ducts, to the tops of the segments 3 and thence to the cushion space 12.
  • FIGS. 1 and 2 show the skirt assembly divided intosix compartments, two on each side of the vehicle and two around the bow of the vehicle.
  • the lateral boundary of the air cushion is completed by a stern skirt 14 which may be similar to the bow and side skirts already described.
  • the stern skirt 14 may be a simple pressurised flexible member without depending segments, or may be any other suitable flexible barrier.
  • FIG. 3 shows how the plan area of the air cushion is variable by varying the ratio of the pressure in the compartments 7 to the pressure in the air cushion area, signified hereafter in the specification as Pb/Pc.
  • the pressure in the air cushion space 12 generates a force represented by the arrow 15 which is restricted by the strength of the skirt assembly, and the configuration of the skirt assembly depends upon a balance of these two factors.
  • Pb/Pc is high, for example 2.5
  • the outline of the skirt assembly is as shown by the long dashed lines 16 and the lateral position of the lower tip of the skirt assembly is on the vertical line '17.
  • Pb/Pc is low, for example 1.3
  • the outline of the skirt assembly is as shown by the short dashed lines 18 and the lateral position of the lower tip of the skirt assembly has moved to the vertical line 19.
  • the distance X between the lines 17 and 19, therefore, represents an increase in the plan dimensions of the air cushion.
  • an increase in the plan area of the air cushion is obtained by reducing the Pb/Pc ratio.
  • the vertical'distance between the underside of the rigid part of the vehicle, represented by the skirt attachment point 4, and the lower tip of the skirt assembly is Y1.
  • the height of the same skirt assembly may be reduced by reducing Pb/Pc (short dashed outline 18), so that the height of the skirt assembly becomes Y2.
  • the change in the vertical heights Y3 and Y4 of the segments is much less than the change of the overall skirt assembly heights Y1 and Y2, so that in the high Pb/Pc case the segment height Y3 is 50% of the skirt assembly height Y1, and in the low Pb/Pc case the segment height Y4 is 70% of the skirt assembly height Y2.
  • the skirting assembly is arranged so that the distance W between the skirt attachment points 4 and 5 is greater than 0.9 times the vertical distance between the underside of the rigid structure of the vehicle and the lower tip of the skirt assembly.
  • each compartment assumes the circular configuration indicated by the chain lines 20, and, when the vehicle moves through the water, the action of the water causes the segments 3 to fold against the surface of the compartments.
  • the compartments at the sides of the vehicle have no segments depending therefrom and the compartments are of a size which, in cooperation with the parts of the skirting assembly at the bow and stern, provide an even hemline.
  • the skirting assembly at the bow and the stern of the vehicle is arranged to be depressurised and retracted so that, when the vehicle is in a displacement water craft phase, it is supported by the compartments at each side, and the bow and stern skirt assemblies are clear of the water.
  • a flexible skirt assembly forming at least part of a barrier to the cushion, and including at least one upper, inflatable, flexible chamber and a plurality of juxtaposed, discrete, flexible segments depending from the upper chamber, wherein the upper inflatable, flexible chamber is inflated by pressurized fluid to a pressure between 1.15 and 5 times the pressure of the cushion.
  • a flexible skirt assembly for a vehicle which, during at least one phase of operation, receives support from at least one cushion of pressurized fluid, the skirt assembly forming at least part of a barrier to the cushion and including at least one upper inflatable, flexible chamber and a plurality of juxtaposed, discrete, flexible segments depending from the upper chamber, the upper inflatable, flexible chamber including a sheet of flexible impermeable material attached at first and second points to structure carried by the vehicle to form a depending loop in a substantial vertical cross section, wherein the distance between the first and second points of attachment of the sheet is greater than 0.9 times the vertical distance between the underside of the rigid structure of the vehicle at the lowermost of said points of attachment and the lower tip of the flexible skirt assembly, and the pressure within the inflatable, flexible chamber is at least 1.15 times the cushion pressure.
  • each compartment is provided with a selectively variable volume accumulator in communication therewith.
  • variable volume accumulator includes a rigid rectangular member pivotally attached, along one of its rectangular sides, to a rigid part of the vehicle, and flexible impermeable sheets interconnecting the free edges of the rigid rectangular member and the rigid structure of the vehicle.
  • a vehicle which, in one phase of its operation, receives support from at least one cushion of pressurized fluid, at least part of the lateral boundary of the cushion area being defined by a flexible skirt assembly including an inflatable, flexible chamber divided into a plurality of compartments attached to the rigid part of the vehicle at inner and outer points, wherein the distance between the inner and outer attachment points is greater than 0.9 times the vertical distance between the underside of the rigid structure of the vehicle at the lowermost of said points of attachment and the lowest part of the flexible skirt assembly, and at least one compartment is in connection with a variable volume fluid accumulator, the pressure within the compartments and accumulator being between 1.15 and 5 times the pressure of the cushion.

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  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Combined Devices Of Dampers And Springs (AREA)
  • Air Bags (AREA)
  • Mattresses And Other Support Structures For Chairs And Beds (AREA)
US730857A 1967-06-22 1968-05-21 Flexible hulls Expired - Lifetime US3512603A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB28955/67A GB1190206A (en) 1967-06-22 1967-06-22 Improvements in or relating to Flexible Skirt Assemblies for Air Cushion Vehicles

Publications (1)

Publication Number Publication Date
US3512603A true US3512603A (en) 1970-05-19

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Family Applications (1)

Application Number Title Priority Date Filing Date
US730857A Expired - Lifetime US3512603A (en) 1967-06-22 1968-05-21 Flexible hulls

Country Status (6)

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US (1) US3512603A (fr)
DE (1) DE1756563A1 (fr)
ES (1) ES355296A1 (fr)
FR (1) FR1572665A (fr)
GB (1) GB1190206A (fr)
NL (1) NL6807830A (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3672461A (en) * 1968-11-22 1972-06-27 British Hovercraft Co Ltd Flexible skirt assemblies for air cushion vehicles
US3779334A (en) * 1972-06-07 1973-12-18 Aerojet General Co Cells for fluid cushion vehicles
US3882960A (en) * 1974-04-18 1975-05-13 Us Navy Ride quality control for surface effects craft
US3892287A (en) * 1973-09-20 1975-07-01 Sun Oil Co Vacuum ice anchor
US3907061A (en) * 1972-09-18 1975-09-23 Hovermarine Transport Ltd Gas-cushion vehicles
US4209400A (en) * 1978-02-06 1980-06-24 Suntech, Inc. Oil spill cleanup method and apparatus
US4383664A (en) * 1977-09-16 1983-05-17 The United States Of America As Represented By The Secretary Of The Air Force Vibration suppressing trunk fingers for air cushion devices
US5909857A (en) * 1995-10-31 1999-06-08 Filimonov; Alexandr Iosifovich Filimonov hybrid dirigible craft
CN105691569A (zh) * 2016-02-03 2016-06-22 江苏科技大学 一种可变空间多球交接耐压装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3990533A (en) * 1974-02-22 1976-11-09 British Hovercraft Corporation Limited Skirts for air cushion vehicles

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3424266A (en) * 1963-06-21 1969-01-28 Hovercraft Dev Ltd Gas - cushion vehicles with multi-stage flexible skirts and attitude correcting means therefor

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3424266A (en) * 1963-06-21 1969-01-28 Hovercraft Dev Ltd Gas - cushion vehicles with multi-stage flexible skirts and attitude correcting means therefor

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3672461A (en) * 1968-11-22 1972-06-27 British Hovercraft Co Ltd Flexible skirt assemblies for air cushion vehicles
US3779334A (en) * 1972-06-07 1973-12-18 Aerojet General Co Cells for fluid cushion vehicles
US3907061A (en) * 1972-09-18 1975-09-23 Hovermarine Transport Ltd Gas-cushion vehicles
US3892287A (en) * 1973-09-20 1975-07-01 Sun Oil Co Vacuum ice anchor
US3882960A (en) * 1974-04-18 1975-05-13 Us Navy Ride quality control for surface effects craft
US4383664A (en) * 1977-09-16 1983-05-17 The United States Of America As Represented By The Secretary Of The Air Force Vibration suppressing trunk fingers for air cushion devices
US4209400A (en) * 1978-02-06 1980-06-24 Suntech, Inc. Oil spill cleanup method and apparatus
US5909857A (en) * 1995-10-31 1999-06-08 Filimonov; Alexandr Iosifovich Filimonov hybrid dirigible craft
CN105691569A (zh) * 2016-02-03 2016-06-22 江苏科技大学 一种可变空间多球交接耐压装置

Also Published As

Publication number Publication date
GB1190206A (en) 1970-04-29
ES355296A1 (es) 1969-12-16
FR1572665A (fr) 1969-06-27
DE1756563A1 (de) 1970-05-06
NL6807830A (fr) 1968-12-23

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