US3388766A - Fluid cushion device for ground effect vehicles and the like - Google Patents

Description

June 18, 1968 J. H. BERTIN 3,

FLUID CUSHION DEVICE FOR GROUND EFFECT VEHICLES AND THE LIKE Original Filed Jan. 11, 1962 2 Sheets-Sheet 1 Inuenor Tear; Ber/fin CSWE MMW 1% fowneys J. H. BERTIN June 18, 1968 FLUID CUSHION DEVICE FOR GROUND EFFECT VEHICLES AND THE LIKE 2 Sheets-Sheet 2 Original Filed Jan. 11 1962 QN mm Imnswo jean Barin United States Patent 3,388,766 FLUID CUSHION DEVICE FOR GROUND EFFECT VEHICLES AND THE LIKE Jean H. Eertin, Neuilly-sur-Seine, France, assignor to Societe Bertin & 'Cie, Paris, France, a company of France Original application Jan. 11, 1962, Ser. No. 165,634, now Patent No. 3,263,764, dated Aug. 2, 1966. Divided and this application Oct. 20, 1965, Ser. No. 498,250 Claims priority, application France, June 30, 1961,

866,604, Patent 80,047 8 Claims. (Cl. 180-127) This is a divisional application of my co-pending application Ser. No. 165,634 filed Ian. 11, 1962, now Patent No. 3,263,764.

The present invention relates to ground effect vehicles or like movable bodies sustained at a small distance from a ground, sea or other surface by means of compressed fluid cushions, in a known manner.

One of the objects of the present invention is to reduce to a minimum the unavoidable leakage of fluid from said cushions and the compressed fluid consumption.

Another object of this invention is to provide fluidcushion devices which will permit the vehicle to negotiate obstacles without damage and without unduly increasing its height above the ground.

A further object of this invention is to provide fluidcushion devices offering a good resistance to wear and tear, and yet light and cheap.

In accordance with the present invention, the fluidcushion device comprises a skirt made of supple, fluidtight, wear and tear resisting material, adapted to be tensioned by internal over-pressure into a shape of generally conical or cylindro-conical shape having a downwardly tapering cross-section, which automatically gives the flaccid skirt a stable shape when internal pressure is exerted and, in addition, the forces of internal pressure exer'ted on the tapering portion will give rise to a vertical component which puts the skirt under stress longitudinally.

Other objects and advantages of the present invention will appear in the following description with reference't the accompanying drawings in which:

FIGURE 1 is a diagrammatic elevation view, partly in section of a ground effect vehicle.

FIGURE 2 is a corresponding front elevation view.

FIGURE 3 shows in vertical section a wholly frustoconical skirt in accordance with the present invention.

FIGURE 4 illustrates similarly a cylindro-conical form of skirt.

FIGURES 5 and 6 show two alternative embodiments of such a skirt.

FIGURES 7 and 8 are respectively a side elevation and a plan view of a preferred arrangement of skirts.

FIGURE 9 illustrates a vehicle with varied skirts.

Referring now to FIGURES 1 and 2, there is shown thereon a platform 1 with four gaseous cushions, each supplied by three ejectors 3, the inductive nozzles 4 of which branch off the discharge duct of a compressed gas generator 5, for instance a gas-turbine engine.

Each of said gaseous cushions is of the plenum chamber type and confined within a skirt 2 made of supple material and mounted on a supporting frame 7 gimballed by means of two horizontally opposed pivots 8 and supported by two horizontally opposed pivots 10 solid with the platform 1 and set at right angles to the axis of the pivots 8. The pivots 10 are preferably fixed to the walls of a flotation tank 21 disposed inside each cushion.

The upper portion of each skirt 2 provides an oscillation joint, an example being bellows joint 11, whereby the skirt is able to move freely in all directions and full tightness with minimum friction is ensured.

Through actuating means well known per se, such as the cable and pulley assembly shown in FIGURE 8 of Parry 2,953,320, a flight control lever 12 controls the pivotal motion of the skirts about the two perpendicular axes containing respectively the pivots 8 and the pivots 10.

The platform is further equipped with a front orientable wheel 13 and a rear wheel 14 driven by an engine 17, for providing positive (friction) guidance and propulsion in a manner well known in the motorcycle art. The wheels are linked to the platform 1 by arms 15, 16 provided with suspension elements 18 and 19 designed to support only 10 to 20% of the total weight of the vehicle, the major part of the weight being supported by the gaseous cushions. The suspension elements may be adapted to permit stiffness adjustment, as shown for instance in Brueder 2,757,376.

Valves 20 enable the compressed gas supplied by the gas generating engine 5 to be distributed as desired to the various cushions.

After the engine 5 has been started up, the platform 1 rises on its air cushions and may be piloted by movement of the control lever 12 which orientates the skirts 2. Accelerations obtained thereby, however, must be kept to a low value in order to avoid diminishing the lifting efliciency, and such acceleration will therefore be suited to translational motion and to low speed manoeuvering.

As a part of the weight of the vehicle is supported by the wheels 13, 14, the propulsion of said vehicle may be effected by means of the rear wheel and the accelerations and decelerations exceed those attained by aerodynamic means, with yet a good propulsive efficiency. The tandem wheels will in fact ensure good stability when travelling on the ground, even at cruising speeds, if they support 10 to 20% of the weight and if the front wheel 13 is steerable as said hereinbefore. The wheels may be fitted with tires having treads adapted to ensure good traction with the ground.

The effects of the sideway forces due to the wind are thus reduced, and the corresponding tipping couple may be further counterbalanced by suitably operating the valves 20 in a differential manner.

FIGURE 3 illustrates, in vertical half-section, a conical skirt 2h. The wall of the cushion is in this case inclined, and its open lower end is of smaller area than its upper end fixed to the platform 1 at 34, so that the force of the pressure F, exerted normal to the wall, produces a vertical component V tending to stretch the skirt, in addition to the horizontal component H which maintains the circular planform.

Considering now FIGURE 4, it will be seen that a similar result may be obtained by providing a conical portion 2 j, of regularly tapering cross-section, "at the bottom of a cylindrical portion 2i.

In both cases, the shapes provided thus ensure stability solely by the action of the internal pressure, and this in turn makes it possible to use thin skirts made of a convenient supple material which is particularly resistant to wear and yet not particularly elastic.

It may be desirable to raise a skirt which has been thus shape-stabilized, or even to raise one of its edges only. FIGURE 5 shows a raisable skirt together with its associated raising device.

This skirt, provided with a conical lower portion 2k, comprises an upper bellows-type portion 2l. Rigid hoops 35 prevent any increase in diameter of the bellows. The bottom hoop 35k is connected by cables 36, symmetrically disposed in plan view, to hoist gears such as 37 for adjusting the height of the skirt.

Thus the raising of a skirt may be under the control of a detected obstacle ahead of it, in which case a mechanical or electro-optical feeler or sensing system such as disclosed in Fert, United States 2,507,001 or Boncompain, United States 2,535,720, is provided to operate the hoist gear, but of course it will be understood that such control may be entrusted to the pilot if desired. The cables 36 may be connected to a single hoist gear 37 in order to obtain an even raising of the skirt. It is also manifest that the hoist gears 37 may be controlled difierentially if required. The orientation of the resulting efilux provides a means of controlling yawing motion in the platform, and this method of control is equivalent to that used with the gimballed cylindrical skirts described hereabove.

FIGURE 6 illustrates another method of adjusting the length of the skirt. The sides of the skirt are formed in part at least by superposed annular air chambers or tubes 38, the extension of which varies according as the tubes are inflated or not. A simple inflating device is provided in the form of a three-way cock 39, whereby each air tube 38' may be connected through a flexible tube 40 to a pipe supplying gas under pressure, for example to the compressed air pipe 33 upstream of the skirt 2, or to exhaust.

As may be seen from FIGURE 6, it is thus possible to provide a skirt which has a bottom conical portion and which is controlled pneumatically throughout. More specifically, as explained above, the bottom conical portion gives rise to a downwardly directed component (of. V on FIGURE 3) of force which tends to stretch the skirt longitudinally. If the air tubes 38 are all deflated (as illustrated in the case of the lowest one in FIGURE 6), the skirt will be stretched to its maximum length. The inflation of one or more air tubes 38 causes a corresponding shortening of the skirt and therefore a corresponding raising of its lower rim, the minimum length and therefore the highest raising being obtained by fully inflating all the air tubes 38. If this proves to be insufficient, the purely pneumatical control of the skirt length by means of the air tubes 38 may be supplemented by a mechanical control such as by means of a hoist gear 37 as explained with reference to FIGURE 5. In this case, the air tubes 38 will be again deflated to allow full effectiveness of the hoist gear 37.

It is to be noted that in all the embodiments of skirts illustrated in FIGURES 3 to 6, the flaccid skint, when subjected to internal overpressure, assumes a relatively rigid outline in the shape of a geometrical solid of revolution, i.e. a shape defined by the motion of a line (generatrix) about an axis, this line remaining in contact with a curve (directrix) extending in a plane perpendicular to this axis. In the above embodiments, the directrix is a circle centered on the longitudinal aixs of the skirt, whereas the generatrix is an oblique straight line in FIGURE 3, a vertical straight line followed by an oblique straight line in FIGURE 4, a zig-zag line followed by an oblique straight line in FIGURE 5, an undulated line followed by an oblique straight line in FIGURE 6.

Thus, in every case, this revolution shape has a crosssection which decreases toward the outlet or lower open end of the skirt due to the form of the generatrix which is either entirely (FIGURE 3) or at least partly (FIGURES 4, 5 and 6) an oblique straight line, this rectilinear gen-- eratrix or rectilinear portion of the generatrix generating a frusto-conical shape. In other words, the skirt, when subjected to internal overpressure, is in the shape of a frustum of a cone from end to end (FIGURE 3) or at least toward its outlet end (FIGURES 4, 5, and 6).

With a view to ensuring an even flow and a correct distribution of air or other gas delivered into the skirt, it has been found convenient to fit a special distributor device at the outlet of the feed pipe 33. Such a distributor device is shown in FIGURE 3 and consists of a plate 33a which extends across the outlet of the pipe 33 and which depends from supports such as 331).

A preferred distributor device is illustrated in FIG- URE 4 and consists of a ported plate 33c, which is dished in order to better withstand the pressure and which is fixed to the platform along its periphery. By way of indication, such a ported plate may have 30%, say, of its area perforated and absorb about 10% of the overpressure exerted by the gas discharged from the pipe 33. I

The various drawbacks that arise from the discharge, into the capacity bounded by a skirt, of a high speed jet of small cross-section may be avoided by the use of such distributor devices: one of the most serious drawbacks is the tendency of the skirt to be entrained by the jet, thereby causing the supple wall to form folds and to flap about and the jet to discharge directly into the open and to impinge violently on the ground, which in turn produces an eroding effect on the soil and gives rise to dust clouds and loss of lift when the lower edge of the skirt is distant from the ground.

Such devices or equivalents thereof may be used with advantage in all the forms of construction illustrated in the figures on the accompanying drawings.

Individual or elmental skirts such :as described above are preferably provided in large number and clustered together to increase platform stability, but this in turn implies a large total efllux or leakage perimeter. Therefore, when it is desired to achieve high lift efficiency, an encompassing peripheral skirt may be used in conjunction with the clustered elemental skirts. Referring now to FIG- URES 7 and 8, there is illustrated thereon a peripheral skirt 41 which is frusto-conical to some degree in side elevation and has a circular dual-lobe planform. Such a skirt may be supplied separately, at an adjustable pressure, rather than be only fed with the leakages from the inner elemental skirts 2.

Adjustment of the relative heights of the skirts 2 and 41 allows selecting for the platform 1 either a high degree of stability (when the skirts 2 are relatively long with reference to the skirt 41), or great lifting efficiency (when the skirt 41 is relatively long with reference to the skirts 2).

An improvement which is applicable to platforms with multiple skirts consists in imparting diiferent elasticity characteristics to the elemental skirts supporting such platforms. As will be readily understood, the geometrical size of each skirt, namely its height and diameter, and its volume in particular, together with its stiffness and the dimensions of its associated supply duct, all affect the instantaneous rate of leak-age and determine a natural period of vertical oscillations of the corresponding air cushion. If all the skirts were identical, such vertical oscillations might give rise to resonance phenomena which may detrimentally affect overall platform sustention. On the other hand, if the elemental skirts be given different sizes, as shown in FIGURE 9, then the natural oscillation periods of the various air cushions will be different and the sustention will tend to be aperiodic.

Thus, in vehicles of this type, the lift and guidance functions may be fulfilled, either independently or jointly, by several different elements such as wheels and air cushions. Such vehicles should extend both the field of application and the capabilities of wheeled vehicles used heretofore, in particular over widely varying ground surfaces where deep mud, snow or sand may be encountered.

Obviously, the number of air cushions, compressed gas generators, ejectors land so on may be modified as required, and it will be well understood by those skilled in the art that various further changes and modifications may be made in the presently preferred embodiments of the ground effect platform herein-before disclosed, within the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. A skirting device to be fitted to ground effect vehicles or like bodies movable along a bearing surface and designed, in operation, for laterally bounding a fluid cushion formed against said surface, wherein the improvement comprises, in longitudinal succession, a body portion made of superposed inflatable tubes, and an end portion made of thin, flaccid, fluidtight material and tapering toward an end orifice designed, in operation, to move adjacent to and opposite said surface.

2. A movable body of the ground effect type comprising a support frame spaced from a bearing surface along which said body is designed to move, and a skirting device fitted to said frame and designed, in operation, for laterally bounding a fluid cushion formed against said surface, said skirting device comprising, in longitudinal succession, a body portion mad of superposed inflatable tubes, and an end portion made of thin, flaccid, fluidtight material and tapering toward an end orifice designed, in operation, to move adjacent to and opposite said surface.

3. A movable body of the ground effect type comprising a support frame spaced from a surface along which said body is designed to move, and a fluid pressuriza'ble skirt fitted to said frame and designed, in operation, for laterally bounding a fluid cushion formed against said surface, said skint being made of thin, flaccid, fluidtight material and ending with an orifice designed, in operation, to move adjacent to and opposite said surface, wherein the improvement comprises a tapering end portion for said skirt extending over a substantial fraction of the overall length measured from said frame to said orifice, of frustoconical revolution shape having an inclined rectilinear generatrix defined by two points spaced apart from each other a distance whereby said points define a straight line of substantial length, and a circular end rim bounding said orifice and forming the smaller base of said frustoconical shape.

4. A body as claimed in claim 3, wherein said skirt further comprises a body portion of cylindrical shape connected to said frustoconical end portion at the larger base thereof and extending said end portion away from said orifice thereof, whereby the skirt has a cylindroconical revolution shape.

5. A body as claimed in claim 4, wherein said cylindrical body portion comprises superposed inflatable tubes.

6. A body as claimed in claim 4, wherein said cylindrical body portion comprises a section in the form of bellows.

7. A body as claimed in claim 3, wherein said skirt further comprises a body portion of frustoconical revolution shape having the same inclined rectilinear generatrix as said end portion and extending the same away from the orifice thereof, whereby the skirt has a frustoconical shape substantially from end to end.

8. A body as claimed in claim 3, comprising a plurality of separate and distinct fluid-pressurizable skirts fitted to said frame and made of thin, flaccid, fluidtight material, each of said skirts having a tapering end portion of frustoconical revolution shape with an inclined rectilinear generat-rix and a circular end rim bounding an orifice.

References Cited UNITED STATES PATENTS 2,743,787 5/1956 Seck 7 3,052,483 9/1962 Petersen 180-7 3,055,446 9/ 1962 Vaughen 1807 3,082,836 3/1963 Billrnan 180-7 3,118,513 1/1964 Cockerell 180--7 3,134,452 5/ 1964 Latimer-Needh am 180-7 3,182,739 5/ 1965 Cockerell a 1807 FOREIGN PATENTS 246,358 9/ 1960 Australia. 860,781 2/ 1961 Great Britain.

A. HARRY LEVY, Primary Examiner.

Claims (1)

1. 3. A MOVABLE BODY OF THE GROUND EFFECT TYPE COMPRISING A SUPPORT FRAME SPACED FROM A SURFACE ALONG WHICH SAID BODY IS DESIGNED TO MOVE, AND A FLUID PRESSURIZABLE SKIRT FITTED TO SAID FRAME AND DESIGNED, IN OPERATION, FOR LATERALLY BOUNDING A FLUID CUSHION FORMED AGAINST SAID SURFACE, SAID SKIRT BEING MADE OF THIN, FLACCID, FLUIDTIGHT MATERIAL AND ENDING WITH AN ORIFICE DESIGNED, IN OPERATION, TO MOVE ADJACENT TO AND OPPOSITE SAID SURFACE, WHEREIN THE IMPROVEMENT COMPRISES A TAPERING END PORTION FOR SAID SKIRT

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