GB1566723A - Creation of Inventions and Patents with Artificial Intelligence

GB1566723A – Skrits for gas cushion vehicles
– Google Patents

GB1566723A – Skrits for gas cushion vehicles
– Google Patents
Skrits for gas cushion vehicles

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Publication number
GB1566723A

GB1566723A
GB12257/76A
GB1225776A
GB1566723A
GB 1566723 A
GB1566723 A
GB 1566723A
GB 12257/76 A
GB12257/76 A
GB 12257/76A
GB 1225776 A
GB1225776 A
GB 1225776A
GB 1566723 A
GB1566723 A
GB 1566723A
Authority
GB
United Kingdom
Prior art keywords
tie means
adjusting
lever
skirt
vehicle
Prior art date
1976-03-26
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

Application number
GB12257/76A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Hovercraft Development Ltd

Original Assignee
Hovercraft Development Ltd
Priority date (The priority date 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 date listed.)
1976-03-26
Filing date
1976-03-26
Publication date
1980-05-08

1976-03-26
Application filed by Hovercraft Development Ltd
filed
Critical
Hovercraft Development Ltd

1976-03-26
Priority to GB12257/76A
priority
Critical
patent/GB1566723A/en

1977-03-22
Priority to US05/780,104
priority
patent/US4111276A/en

1977-03-24
Priority to CA274,693A
priority
patent/CA1054191A/en

1977-03-25
Priority to FR7710146A
priority
patent/FR2345327A2/en

1977-03-26
Priority to JP3392477A
priority
patent/JPS52135117A/en

1980-05-08
Publication of GB1566723A
publication
Critical
patent/GB1566723A/en

Status
Expired
legal-status
Critical
Current

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Classifications

B—PERFORMING OPERATIONS; TRANSPORTING

B60—VEHICLES IN GENERAL

B60V—AIR-CUSHION VEHICLES

B60V1/00—Air-cushion

B60V1/16—Flexible skirts

B—PERFORMING OPERATIONS; TRANSPORTING

B60—VEHICLES IN GENERAL

B60V—AIR-CUSHION VEHICLES

B60V1/00—Air-cushion

B60V1/11—Stability or attitude control

Description

PATENT SPECIFICATION
( 21) Application No 12257/76 ( 22) Filed 26 March 1976 ( 19) ( 61) Patent of Addition to No 1 439 326 dated 5 June 1973 ( 23) Complete Specification filed 14 March 1977 ( 44) Complete Specification published 8 May 1980 ( 51) INT CL ‘ B 60 V 1/16 ( 52) Index at acceptance B 7 K DC ( 11) ( 72) Inventors JOHN EDWARD RAPSON and DEAN ALDERS ( 54) IMPROVEMENTS IN OR RELATING TO SKIRTS FOR GAS CUSHION VEHICLES ( 71) We, HOVERCRAFT DEVELOPMENT LIMITED, a British Company, of Kingsgate House, 66-74 Victoria Street, London, S.W 1, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method bv which it is to be performed, to be particularly described in
and by the following statement: –
This invention relates to modifications of or improvements in cushion containing skirts of gas cushion vehicles the subject of Patent Specification No 1,439,236, hereinafter called the parent specification, in which there is described and claimed a skirt for a gas cushion vehicle comprising upper and lower parts of flexible sheet material, the upper part being connected to the vehicle body so as to be deflectable relative thereto, at least the lower part comprising a contiguous succession of independently deflectable flexible wall members each having an outer portion which faces the gas cushion and a pair of inwardly extending side portions, the side portions being connected to the vehicle body by tie means, in which adjusting means are provided to cause angular movement of at least inner portions of the tie means about substantially vertical axes passing through their attachments to the vehicle and thereby result in the outer portions of the wall members being moved laterally in a direction towards or away from the vehicle body.
In a preferred embodiment the adjusting means comprise further tie means extending substantially at right angles to the side portions of the wall members and operatively connected to the tie means thereof, and means are provided operative to effect linear movement of the further tie means to cause the said movement of the wall members.
It will be understood that by providing for such adjusting movement of such skirts a shift in the position of the centre of pressure of the gas cushion in relation to the centre of gravity of a vehicle may be occasioned, or fluctuations in cushion pressure may be alleviated By appropriately shifting the centre of pressure of the cushion in relation to the centre of gravity of a vehicle, roll or pitch of the vehicle may be combatted or promoted or general adjustment of the trim of the vehicle may be effected.
It is the object of the present invention to provide an improved mechanism for effecting and controlling movement of the wall members comprising such a skirt.
In accordance with one aspect of the present invention in a gas cushion vehicle having a skirt comprising upper and lower parts of flexible sheet material, the upper part being connected to the vehicle body so as to be deflectable relative thereto, at least the lower part comprising a contiguous succession of independently deflectable flexible wall members each having an outer portion which faces the gas cushion and a pair of inwardly extending side portions, the side portions being connected to the vehicle body by tie means, there is provided a skirt control mechanism comprising adjusting tie means extending substantially at right angles of the said tie means and operatively connected to substantially the mid point thereof, means including a lever system operative to effect linear movement of the adjusting tie means and means to at least restrict movement of the wall members in a direction parallel to the adjusting tie means upon adjusting movement thereof, whereby upon linear movement of the adjusting tie means the said tie means connected to the side portions of the wall members are caused to be angled and thereby result in the outer portions of the wall members being moved in a direction towards or away from the vehicle body, the lever system being mechanically equivalent to the lever system effectively constituted by the said tie means and the said adjusting tie means and arranged to act such that as the mechanical advantage of one lever system alters an equal and op1 566 723 m pl A 2 1,566,723 2 posite alteration occurs in the other lever system so that for a given cushion pressure the force required to operate the adjusting tie means is maintained substantially constant at least over a predetermined range of movement.
In accordance with another aspect of the invention a skirt for a gas cushion vehicle comprises upper and lower parts of flexible sheet material, the upper part being connected to the vehicle body so as to be deflectable relative thereto, at least the lower part comprising a contiguous succession of independently deflectable wall members each having an outer portion which faces the gas cushion and a pair of inwardly extending side portions, tie means connecting the side portions to the vehicle body and adjusting means for causing the tie means to swing in a substantially horizontal plane about their attachments to the vehicle and thereby result in the outer portions of the wall members being moved laterally relative to the vehicle body, the adjusting means comprising further tie means extending substantially at right angles to and connected substantially to the mid point of the ties of the side portions, means including a lever system operative to effect linear movement of the further tie means to cause the said movement of the skirt and means for restricting movement of the wall members in a direction parallel to that of the further tie means upon adjusting movement thereof, in which the said lever system includes a lever having at least one arm the length of which is equivalent to half the operative length of the tie means of the side portions, the angle formed between the said arm of the lever and the said further tie means being arranged to equal half the angle included between the parts of the ties of the side portions on either side of their connection to the said further tie means and control cables for operating the lever are maintained in a predetermined angular relationship with the adjusting tie means whereby the mechanical advantage obtained via the lever alters in an equal and opposite sense to alterations in the mechanical advantage of the system comprising the said further tie means and the tie means of the side portions upon movement thereof, so that for a given cushion pressure the force required to be applied to the lever to effect the said skirt movement is maintained substantially constant.
According to a further aspect of the invention means for horizontally adjusting the boundary of a cushion of a gas cushion vehicle in a direction towards or away from the same comprises a skirt having upper and lower parts of flexible sheet material for containing the cushion at least in part, the upper part being connected to the vehicle body so as to be deflectable relative thereto and at least the lower part comprising a contiguous succession of independently deflectable wall members each having an outer portion which faces the gas cushion and a pair of inwardly extending side portions con 70 nected by tie means to the vehicle body, adjusting tie means extending substantially at right angles to and connected to the mid point of the tie means of the side portions, means including a lever system operative to 75 effect linear movement of the adjusting tie means and means to at least restrict movement of the wall members in a direction parallel to the adjusting tie means upon adjusting movement thereof, whereby upon 80 linear movement of the adjusting tie means the tie means connected to the side portions are caused to be angled and thereby result in the outer portions of the wall members being moved substantially horizontally in a 85 direction towards or away from the vehicle body, the lever system including at least one arm of a length equivalent to half of the operative length of the side portions of the wall members and so arranged as opera 90 tively to constitute with the said tie means a parallelogram linkage system whereby the force required to operate the said lever is maintained substantially constant for a given cushion pressure 95 The invention is described below with reference to the accompanying drawings in which: Figure 1 is a diagrammatic perpsective view of a gas cushion vehicle showing one 100 embodiment of the skirt control mechanism; Figure 2 is a diagrammatic side elevation of the mechanism of Figure 1; Figure 3 is a diagrammatic side elevation of a modified form of control mechanism; 105 Figures 4 a and 4 b are fragmentary diagrammatic plan and end elevational views respectively of a further modification of the control mechanism, Figures Sa and 5 b are fragmentary side 110 elevation and plan views respectively of yet a further modification of the control mechanism; Figures 6 a and 6 b are a diagrammatic side elevation and plan view respectively of 115 yet a further modification of the control mechanism; Figure 6 c is a fragmentary plan view on an enlarged scale of a modification to the mechanism of Figures 6 a and 6 b, 120 Figure 7 is a diagrammatic perspective view of a still further modification of the control mechanism; Figure 8 is a diagrammatic plan view showing an alternative arrangement of skirt 125 ties; Figure 9 is a fragmentary perspective view of a modification of Figure 8; Figures l Oa and l Ob are idealised diagrammatic representations of the lever sys 130 1,566,723 terns exemplified in the embodiments of Figures 1 to 9, and Figures lla and 1 lb are vector diagrams of the forces involved in the lever system when in the positions indicated in Figures a and l Ob respectively.
In accordance with the invention and in all the arrangements illustrated a gas cushion vehicle is equipped with skirts, as best seen in Figures 1 and 4, comprising upper and lower parts formed of flexible sheet material, the upper part comprising a simple sheet forming a loop 1 which is attached at its upper edge to the vehicle body and at its lower edge to the lower part of the skirt.
This lower part comprises a succession of independently deflectable flexible wall members 2 of the kind described in Patent Specification No 1,043,351 each wall member comprising an outer portion 3 and a pair of side portions 4 secured by ties 5 to the body of the gas cushion vehicle Movement of the outer portions of the wall members towards and away from the vehicle body is effected by linear movement of adjusting ties 6 which are secured to the ties 5 intermediate the connections of the latter to the side portions of their associated wall members at 7, and their anchorages to the vehicle body at 8 Longitudinal movement of wall members is at least restricted if not prevented by longitudinally extending restraining ties 9.
In practice to provide for both roll and pitch control it is envisaged that a gas cushion vehicle will be provided with at least four sections of skirt, two on each side of the vehicle, the fore section of skirt on one side being operatively connected with the aft section of skirt on the other side, the arrangement being such that as one of an interconnected pair of skirt sections is moved inwardly the other section moves outwardly, or vice versa.
Referring now to Figures 1 and 2, operation and control of movement of the skirt of a gas cushion vehicle in which the skirt is divided into four sections as mentioned above, is effected by a control column 10 supported intermediate its ends by a universal joint 11 and to one end of which are connected cables 12 a, b, c and d each of which is secured at its other end to one arm of an associated bellcrank lever 13 a, b, c and d The adjusting ties 6 a, b c and d associated with the four aforementioned skirt sections are connected to the other arm of a respective one of the bellcrank levers In the arrangement illustrated the body 14 of the gas cushion vehicle has a frame 15 to which the bellcranks 13 are secured by horizontal pivots 16 The cables 12 are conveniently passed through bushes 17 and pulleys 18 as shown, and are connected to the control column 10 through the intermediary of turnbuckles 19 which in turn are conveniently secured to a plate 20 universally pivotted to the lower end of the control column.
In the modification shown in Figure 3 each control cable 12 is formed in two parts 70 interconnected by a lever 21 which in this case is pivotted at its upper end 22 to the vehicle structure This arrangement avoids wear associated with the use of bushes and should reduce friction and can provide the 75 system with added mechanical advantage.
Additionally the arrangement helps to keep the control wires parallel which is desirable for the efficient operation and balance of the system in operation as will be described 80 hereinafter.
The bellcranks 13, being external the body of the vehicle and one of their arms projecting as it will, depending upon its operating position, below the frame 15, may be prone 85 to damage through accidental contact with obstacles traversed by the vehicle The length of the lower arm of the bellcranks may be relatively shortened to reduce risk of such damage if a lever 23 as illustrated 90 in Figures 4 a and 4 b is employed which is pivotted at its inner end 24 to the vehicle frame 15, in the plane of the ties 5, and to the outer end of which the adjusting tie 6 of the associated skirt section is secured The 95 lever 23 is then in turn connected by a cable acting intermediate its ends, to the lower arm of the bellcrank lever The lever 23 is arranged so as to extend parallel to and to be of the same lengths as the portions of 100 the ties 5 inboard of the adjusting tie 6 so as to be operationally equivalent to the lower arms of the bellchanks in the preceding embodiments, as will be further explained below 105 Clearly, instead of, as in the preceding embodiments, having bellcranks mounted on horizontal axes, cranks acting about substantially vertical axes may be employed.
Such cranks may conveniently as indicated in 110 Figures 5 a and 5 b be formed with a shaft 27 journalled in a sleeve (not shown) passing through the body of the vehicle, the shaft and sleeve being of such a length that the upper end of the sleeve is above the 115 level of the water line when the vehicle floats on water.
A still further alternative arrangement is shown in Figure 6 a and 6 b in which the bellcranks and control cables are all posi 120 tioned beneath the frame of the vehicle.
With such an arrangement a false bottom may be provided for the craft to protect the control cables, pulleys etc so far as possible The lower end of the control column 125 would need to be contained within an air and water-tight housing as indicated at 28.
Although it is convenient, it is by no means essential to employ two-armed or bellcrank levers Thus a one-armed lever 130 1,566,723 1,566,723 as illustrated at 31 in Figure 7 may be used which is operationally equivalent to the lever 23 of Figure 4 and the lower arm of the bellcranks in other embodiments Figure 7 also demonstrates the fact that the lever 31 or its equivalent may be disposed at any convenient point in a lever system, in this case the adjusting ties 6 of the skirt sections each being connected to the lever 31 via a lever 29 pivotted at its centre 30 to the vehicle structure, so that the lever 31 may be located adjacent the control column or wherever else desired.
Although in all the arrangements illustrated in Figures 1 to 7 the adjusting ties 6 lead towards the ends of the craft, the system of ties or part of the system may in fact be reversed so that the adjusting ties converge towards the centre of the craft or the location of the control column In this event the arrangement of the restraining ties 9, which as previously mentioned at least restrict if they do not prevent longitudinal movement of the wall members 2 in sympathy with their associated adjusting ties 6, will be reversed That is to say instead of, as in the arrangements illustrated, being anchored to for example the frame 15 at the opposite end of the vehicle to that of the skirt sections to the side portions of the wall members of which the tie is otherwise coupled at or adjacent the points 7, the ties 9 will be led from those points to the same end of the vehicle as that at which its associated skirt section is situated Such a reversed arrangement of the ties 9 may require the provision of special anchorages disposed outboard of the anchorages 8 of the ties 5 to the vehicle body, so that the ties 9 may extend parallel or as near parallel as practical to the line of anchorages 8 Although certain of the illustrations may give a distorted appearance to the contrary, in practice with the arrangements shown the relative distances between one skirt section and the opposite end of the vehicle will be such that the divergence of the ties 9 over their length coupled to the side portions of the wall members, from a direction substantially parallel with the adjacent side of the vehicle body, is insignificant.
An alternative arrangement of ties which avoids the need for restraining ties 9 as such, is shown in Figures 8 and 9 Thus the ties 5 are duplicated to adopt a diamond formation in operation, one tie 5 of a pair connected to a given one of the side portions of the wall members being operable by a first adjusting tie 61, and the other tie 5 of the pair being operable by a second adjusting tie 611, the latter being passed round a pulley 26 so as to be operable in unison with the tie 61 with which it shares a common connection point to the lever 13 In Figure 9 a simplification is shown in which the ties 61 and 611 are different runs of the same cable As shown a turnbuckle 32 is conveniently provided to allow for such adjustment as may be necessary to ensure symmetry in the tie system 70 The basic operation of the skirt sections, i.e the manner in which movement of the wall members making up the skirt sections is effected, is the same as described in the parent specification For practical purposes 75 the normal operating or datum position of the skirt sections is arranged to be one in which the adjusting ties 6 hold the ties 5 of the wall members in an angled, chevron or diamond formation as illustrated Appropri 80 ate movement of the adjusting ties may then either allow the wall members to move away from the adjacent structure of the vehicle to which they are secured, under the influence of cushion pressure, or alterna 85 tively to be moved towards the vehicle structure against the forces exerted thereon by cushion pressure.
The manner in which, in accordance with the invention the alternative lever systems 90 described operate to maintain the force required to effect controlled movements of the skirt or skirt section, substantially constant, may best be understood by reference to the diagrams of Figures 10 and 11 95 The outwardly directed force C due to cushion pressure acting on the skirt is taken to be constant This force is of course reacted by tension in the side portions 4 of the wall members of the skirt and the ties 100 back to the anchorages 8 of the ties The magnitude of the tension T in the ties 5 and the tension L in the adjusting ties 6 depends of course on the angular setting of the two parts of ties 5 With the tie 6 connected to 105 the mid point of the ties 5, and the connections 7 of the ties 5 to the side portions 4 held against longitudinal movement by the previously described restraining ties 9 or their equivalent, between the two posi 110 tions of the system shown in Figures 1 ia and l Ob the relative magnitudes of the tentions T and L will vary as indicated by vector diagrams lla and 1 lb respectively Since however, in accordance with the invention 115 the lever system incorporating the lever B is mechanically equivalent to the lever system effectively constituted by the ties 5 and 6, and the arrangement is such that as the mechanical advantage of one lever system 120 alters an equal and opposite alteration occurs in the other lever system, the force S required to be transmitted by the control cables 12 to the lever B to operate the tie 6 remains constant as also demonstrated by 125 the vector diagrams.
To achieve this end, in the simple idealised system of diagrams 10 the lever B has an operative length equal to half the operative length of the ties 5 Furthermore it is ar 130 1,566,723 ranged that the angle Y between the adjusting tie 6 and the lever B is substantially half the angle X included between the two parts of each tie 5 It is also arranged that the angle Y and the angle Z formed between the control cable 12 and the lever, amount in sum to 900.
Once it is arranged that the force in a control cable 12 required to effect movement of its associated adjusting tie is maintained substantially constant, at least over the range of movement envisaged, it will be seen that it can be arranged that the forces exerted on the control column by the cables of each skirt section of an interconnected pair of skirt sections are balanced one by another, with the result that in principle the only force required on the control column to operate the skirt adjusting mechanism will be that needed to overcome friction in the system This of course presupposes that upon movement of the skirt sections there is substantially no alteration in the volume of the cushion they contain i e.
fluctuations of cushion pressure do not occur consequent upon the skirt movements.
Preferably all the skirt sections are of the same form and of equal length so that the arrangement of all the ties and cranks or levers may be the same If necessary, however, interconnected skirt sections may be of different lengths or forms provided the mechanical advantages of the cranks or levers employed are suitably arranged to i 5 cater for the difference in the total forces exerted on one skirt section as opposed to the other by cushion pressure.
In embellishment of the above general description of the skirt control mechanism of this invention and first with reference to Figures 1-3 it will be appreciated that it is the lower arm of each lever 13 which is equivalent to the lever B of Figure 10, the operative length of the lower arms of the levers 13 being equal to half the operative length of the ties 5, to the mid point of which their associated adjusting tie 6 are connected.
In the arrangement of Figures 4 a and 4 b it is each lever 23 which is equivalent to the lever B, the bellcranks 13 the lower arms of which in the special case illustrated are shortened compared with those of Figures 1 to 3, being arranged through the position of the connections of the cables 25 to the levers 23, to have the same mechanical advantage as the bellcranks of Figures 1 to 3.
In Figure 5 is is again the lower arm of the two-armed lever which is the equivalent of lever B, and in Figure 6 it is the outer arm of the bellcrank In both these cases in which the relevant lever arms are disposed and act in the same plane as the ties 5 they of course extend parallel to the inner ports tions of the ties 5 as does the lever B of the idealised diagrams of Figure 10 The predceing embodiments however, and that of Figure 7 where the lever 31 is equivalent to lever B, indicate that the spatial disposition of the lever B or equivalents thereof 70 is a matter of choice.
All that is necessary, as mentioned above and as indicated in Figure 6 c, is that the included angle X between the two parts of the ties 5 is twice the angle Y formed be 75 tween the adjusting ties 6 and the first arm of the bellcrank lever 13, and the angle Y plus the angle Z formed between the control cable 12 and the second arm of the bellcrank in the sum amount to 90 When as 80 in the case illustrated a right angled bellcrank is employed then the adjusting ties 6 and cables 12 will extend parallel to each other.
In practice it will be undersstood there 85 will be a limit to the degree to which the ties 5 can be “cranked” and also over their range of movement there will be deviations from the desired substantially constant angular relationship between the ties 6 and 90 cables 12 Thus for example, particularly at the extremes of their movement the adjusting ties 6 and control cables 12 associated with a right-angled bellcrank will tend to diverge from their desired parallel relation 95 ship At least over a middle operating range however this deviation will be insufficient to cause any great change in the substantially constant force to be applied to and by the cables 12 100 Although it has been assumed in the foregoing that the total forces exerted on a skirt section, and to be restrained inter alia by the control system, will remain substantially constants cases can occur in which this is 105 not so Thus for example if the vehicle is rolled such that the lower edges of the wall mmebers of one skirt section partly collapse into contact with the surface, then of course the area of that partly collapsed skirt sec 110 tion on which the cushion pressure acts will be less than the area of the uncollapsed skirt section on the opposite side of the craft to which the first mentioned section is interconnected Thus the desired balance in the 115 control system will be upset In order at least to alleviate if not avoid this imbalance, as indicated in Figure 6 c an additional pulley or roller 33 may be provided which will be contacted by the cable 12 when the latter is 120 operated to pull its associated skirt section inwards beyond a predetermined amount.
The result is that the angle Z formed between the cable 12 and the second arm of the bellcrank 13 will be varied and it can 125 be arranged that the change in the angle Z is such that a balance of loads is maintained at the control stick 10 Conversely rollers 33 or their equivalent may be arranged to correct deviation of the control cables towards 130 s 1,566,723 extremes’of their travel tending to vary the angle Z.
As will be noted most clearly from Figures 1 and 6 b the interconnection of the skirt sections via the control column 10 is such that operation of the column is in accordance with normal senses Thus assuming the vehicle is facing in the direction of the arrow A, backward movement of the column 10 will cause inward movement of the two aft skirt sections and outward movement of the two fore sections with the result that the centre of pressure of the cushion will be moved forwardly and the craft will adopt a nose up attitude Similarly movement of the control column to one side will cause the skirt sections on that side to be drawn inwardly and those on the other side to move outwardly with the result’ that the vehicle will roll to the side to which the column is moved With the universal mounting of the control column any combination of rolling and pitching movements of the vehicle may be effected.
The turnbuckles 19 apart from being of use in adjusting the effective lengths of the control cables to take up stretch and to set them to have the ties 5 orientated in the required datum position, may also be employed to adjust the trim of the vehicle Provision may also be made by for example arranging for vertical adjustment of the control column to cause all the skirt sections to be paid out or drawn in and thus adjust the effective area of the cushion and hence the cushion pressure.
Springs (not shown) may be inserted in the control cables 12 in order to introduce a degree of springing into the cushion suspension system.
Apart from selecting the lengths of the lever arm of the bellcranks or other levers when necessary to equalise the forces exerted by the control cables on the control column, these levers may also be selected to minimise the forces which act at the control column Although it is not essential, in the embodiments of Figures 1 to 6 in which the bellcranks are mounted on a separate frame or chassis of the vehicle there is the advantage that this frame or chassis rather than the other structure of the vehicle takes the majority of the loads imposed on the skirt controlling mechanism by cushion pressure.
The arrangement of the control systemalso has the advantage that in the event of one control cable breaking both the skirt section controlled by that cable and its intended interconnected pair will be paid out, there being in the case of neither section anything to resist outward movement of the skirt ‘sections under the influence of cushion pressure -until they are held by straightening of theies 5 The arrangement is thus such that it fails safe Depending upon the degree of movement provided for in the system, to prevent over extension of the skirts in the event of failure of the control mechanism it may be desirable to affix additional ties (not shown) which act in parallel with the ties 5 to limit the extent to which the skirt can move outwardly The limiting position of the skirt is one beyond which the cushion pressure will exert a net upward force on the skirt With skirts as illustrated this point will be reached at approximately the condition when the seal point of the wall members with the subjacent surface comes to lie outboard of the line of attachment of the loop 1 to the vehicle body.
It will be understood that the invention has been described in relation to its most simple forms employing systems directly operable by a control stick Many mechanical equivalents for a variety of the components may manifestly be provided, particularly if the system is applied to large craft Plainly, for example, the control cables 12 may be replaced by servomechanisms operable in any appropriate manner from a central control point.
Finally although the invention has only been described in relation to gas cushion vehicles the control system could equally be applied to similar skirt arrangements employed for containing cushions of pressurised liquid.

Claims (9)

WHAT WE CLAIM IS: 100

1 In a gas cushion vericle having a skirt comprising upper and lower parts of flexible sheet material, the upper part being connected to the vehicle body so as to be deflectable relative thereto, at least the 105 lower part comprising a contiguous succession of independently deflectable flexible wall members each having an outer portion which faces the gas cushion and a pair of inwardly extending side portions, the side 110 portions being connected to the vehicle, body by tie means, the provision of a skirt control mechanism comprising adjusting tie means extending substantially at right angles to the said tie 115 means and operatively connected to substantially the mid point thereof, means including a lever system operative to effect linear movement of the adjusting tie means and means to at least restrict movement of 120 the wall members in a direction parallel to the adjusting tie means upon adjusting movement thereof, whereby upon linear movement of the adjusting tie means the said tie means connected to the side por 125 tions of the wall members are caused to be angled and thereby result in the outer portions of the wall members being moved in a direction towards or away from the vehicle body, the lever system being mechanically 130 1,566,
723 equivalent to the lever system effectively constituted by the said tie means and the said adjusting tie means and arranged to act such that as the mechanical advantage of one lever system alters an equal and opposite alteration occurs in the other lever system so that for a given cushion pressure the force required to operate the adjusting tie means is maintained substantially constant at least over a predetermined range of movement.

2 A gas cushion vehicle as claimed in Claim 1 in which the skirt is formed in at least two sections each provided with a control mechanism, the control mechanisms being operatively interconnected so that the forces exerted on each are balanced the one by the other.

3 A gas cushion vehicle as claimed in Claim 2 in which the skirt is divided into two fore and two aft skirt sections and the fore skirt sections are operatively interconnected to the aft skirt sections on opposite sides of the craft.

4 A gas cushion vehicle as claimed in Claim 1, 2 or 3 in which the lever system comprises a lever the operative length of which is equal to half the operative length of the tie means of the side portions of the wall members and the angle formed between the lever and the adjusting tie is arranged to equal half the angle included between the parts of the ties of the side portions on either side of their connection to the adjusting tie and the lever is in turn operated by means acting at an angle which in sum with the first mentioned angle amounts to 9 T 0.

A gas cushion vehicle as claimed in Claim 4 in which the lever comprises one arm of a right-angled bell crank lever.

6 A gas cushion vehicle as claimed in Claim 1 in which the means for restricting movement of the wall members parallel to the adjusting tie means comprise a duplicate set of tie means connecting the side portions of the wall members to the vehicle body which duplicate tie means are connected to a duplicate adjusting tie means arranged to operate simultaneously with but in the opposite direction to the first mentioned adjusting tie means so that in operation each duplicated pair of tie means connected to the side portions of the wall members adopts a symmetrical diamond formation.

7 A skirt for a gas cushion vehicle comprising upper and lower parts of flexible sheet material, the upper part being connected to the vehicle body so as to be deflectable relative thereto, at least the lower part comprising a contiguous succession of independently deflectable wall members each having an outer portion which faces the gas cushion and a pair of inwardly extending side portions, tie means connecting the side portions to the vehicle body and adjusting means for causing the tie means to swing in a substantially horizontal plane about their attachments to the vehicle and thereby result in the outer portions of the wall members being moved laterally relative to the 70 vehicle body, the adjusting means comprising further tie means extending substantially at right angles to and connected substantially to the mid point of the ties of the side portions, means including a lever system opera 75 tive to effect linear movement of the further tie means to cause the said movement of the skirt and means for restricting movement of the wall members in a direction parallel to that of the further tie means upon 80 adjusting movement thereof, in which the said lever system includes a lever having at least one arm the length of which is equivalent to half the operative length of the tie means of the side portions, the angle formed 85 between the said arm of the lever and the said further tie means being arranged to equal half the angle included between the parts of the ties of the side portions on either side of their connection to the said 90 further tie means and control cables for operating the lever are maintained in a predetermined angular relationship with the adjusting tie means whereby the mechanical advantage obtained via the lever alters in an 95 equal and opposite sense to alterations in the mechanical advantage of the system comprising the said further tie means and the tie means of the side portions upon movement thereof, so that for a given cushion 100 pressure the force required to be applied to the lever to effect the said skirt movement is maintained substantially constant.

8 Means for horizontally adjusting the boundary of a cushion of a gas cushion 105 vehicle in a direction towards or away from the same comprising a skirt having upper and lower parts of flexible sheet material for containing the cushion at least in part, the upper part being connected to the vehicle 110 body so as to be deflectable relative thereto and at least the lower part comprising a contiguous succession of independently deflectable wall members each having an outer portion which faces the gas cushion and a 115 pair of inwardly extending side portions connected by tie means to the vehicle body, adjusting tie means extending substantially at right angles to, and connected to the mid point of the tie means of the side portions,
120 means including a lever system operative to effect linear movement of the adjusting tie means and means to at least restrict movement of the wall members in a direction parallel to the adjusting tie means upon 125 adjusting movement thereof, whereby upon linear movement of the adjusting tie means the tie means connected to the side portions are caused to be angled and thereby result in the outer portions of the wall members 130 be operated substantially as herein described with reference to Figures 1 and 2, 3, 4 a and b, 5 a and b, 6 a and b, 7, 8 or 9 of the accompanying drawings.
11 A gas cushion vehicle in which the cushion is contained at least in part by a skirt as claimed in any one of the claims of the parent specification incorporating the modifications or improvements substantially as herein described with reference to Figures I and 2, 3,4 a and b, 5 a and b, 6 a and b, 7, 8 or 9 of the accompanying drawings.
12 A skirt for a gas cushion vehicle as claimed in any one of the preceding claims which skirt is constructed, arranged and adapted to be adjusted substantially as herein described with reference to Figures 1 and 2, 3, 4 a and b, 5 a and b, 6 a and b, 7, 8 or 9 of the accompanying drawings.
13 Means for horizontally adjusting the boundary of a cushion of a gas cushion vehicle as claimed in any one of the preceding claims constructed, arranged and adapted to be operated substantially as herein described with reference to Figures 1 and 2, 3, 4 a and b, 5 a and b, 6 a and b, 7, 8, 9 or 10 and 11 of the accompanying drawings.
14 A method of adjusting the boundary of the cushion of a gas cushion vehicle substantially as herein described with reference to Figures 1 and 2, 3, 4 a and b, 5 a and b, 6 a and b, 7, 8, 9 or 10 and 11 of the accompanying drawings.
J S SPAIGHT, Chartered Patent Agent, Agent for the Applicants.
being moved substantially horizontally in a direction towards or away from the vehicle body, the lever system including at least one arm of a length equivalent to half of the operative length of the side portions of the wall members and so arranged as operatively to constitute with the said tie means a parallelogram linkage system whereby the force required to operate the said lever is maintained substantially constant for a given cushion pressure.

9 A skirt for a gas cushion vehicle as claimed in Claim 3 of the parent specification in which the further or adjusting tie means is connected to the mid point of the tie means of the said portions and is operated by a lever the lever arm of which is equivalent to half the operative length of the tie means of the side portions and a predetermined angular relationship is maintained between control cables viia which the lever is operated and the adjusting tie means such that as the mechanical advantage of the system comprising the adjusting tie means and the tie means of the side portions alters, the mechanical advantage obtained via the lever alters in an equal and opposite sense so that the force required to be applied to the control cable to effect movement of the 30} outer portions of the wall members in a direction towards or away from the vehicle body is maintained substantially constant for a given cushion pressure.
A gas cushion vehicle as claimed in any one of the preceding claims having a skirt constructed, arranged and adapted to Printed for Her Majesty’s Stationery Office by Burgess & Son (Abingdon), Ltd -1980.
Published at The Patent Office, 25 Southampton Buildings, London, WC 2 A IAY, from which copies may be obtained.
1,566,723

GB12257/76A
1976-03-26
1976-03-26
Skrits for gas cushion vehicles

Expired

GB1566723A
(en)

Priority Applications (5)

Application Number
Priority Date
Filing Date
Title

GB12257/76A

GB1566723A
(en)

1976-03-26
1976-03-26
Skrits for gas cushion vehicles

US05/780,104

US4111276A
(en)

1976-03-26
1977-03-22
Skirts for gas cushion vehicles

CA274,693A

CA1054191A
(en)

1976-03-26
1977-03-24
Skirts for gas cushion vehicles

FR7710146A

FR2345327A2
(en)

1976-03-26
1977-03-25

GAS CUSHION VEHICLE SKIRT

JP3392477A

JPS52135117A
(en)

1976-03-26
1977-03-26
Skirt for air cushion vehicle

Applications Claiming Priority (1)

Application Number
Priority Date
Filing Date
Title

GB12257/76A

GB1566723A
(en)

1976-03-26
1976-03-26
Skrits for gas cushion vehicles

Publications (1)

Publication Number
Publication Date

GB1566723A
true

GB1566723A
(en)

1980-05-08

Family
ID=10001246
Family Applications (1)

Application Number
Title
Priority Date
Filing Date

GB12257/76A
Expired

GB1566723A
(en)

1976-03-26
1976-03-26
Skrits for gas cushion vehicles

Country Status (5)

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US
(1)

US4111276A
(en)

JP
(1)

JPS52135117A
(en)

CA
(1)

CA1054191A
(en)

FR
(1)

FR2345327A2
(en)

GB
(1)

GB1566723A
(en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

DE4219830A1
(en)

1992-06-17
1993-12-23
Abs International Sa St Blaise

Static trim for a hovercraft

Family Cites Families (5)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

CA781806A
(en)

1968-04-02
J. Hardy Derek
Ground effect vehicle

US3532179A
(en)

1965-06-01
1970-10-06
Norman Bryan Mccreary
Aerodynamic lifting device and method of lifting

US3481423A
(en)

1966-10-25
1969-12-02
Cushioncraft Ltd
Means to trim air cushion vehicles

GB1241594A
(en)

1968-03-26
1971-08-04
Vosper Ltd
An improvement in gas-cushion vehicles

GB1439326A
(en)

1972-06-06
1976-06-16
Hovercraft Dev Ltd
Skirts of gas cushion vehicles

1976

1976-03-26
GB
GB12257/76A
patent/GB1566723A/en
not_active
Expired

1977

1977-03-22
US
US05/780,104
patent/US4111276A/en
not_active
Expired – Lifetime

1977-03-24
CA
CA274,693A
patent/CA1054191A/en
not_active
Expired

1977-03-25
FR
FR7710146A
patent/FR2345327A2/en
active
Granted

1977-03-26
JP
JP3392477A
patent/JPS52135117A/en
active
Pending

Also Published As

Publication number
Publication date

FR2345327B2
(en)

1980-10-03

CA1054191A
(en)

1979-05-08

FR2345327A2
(en)

1977-10-21

JPS52135117A
(en)

1977-11-11

US4111276A
(en)

1978-09-05

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