Air cushion vehicles having deflectable wall structures

Claim 1

A VEHICLE FOR OPERATING OVER A SURFACE AND WHICH, IN OPERATION, IS SUPPORTED ABOVE THAT SURFACE, AT LEAST IN PART, BY A CUSHION OF PRESSURISED GAS FORMED AND CONTAINED IN A SPACE BENEATH THE VEHICLE, IN WHICH THE SPACE IS BOUNDED FOR AT LEAST PART OF ITS PERIPHERY BY A DEFLECTABLE WALL STRUCTURE COMPRISING A FLEXIBLE DIAPHRAGM EXTENDING DOWNWARDLY FROM THE BOTTOM SURFACE OF THE VEHICLE AT THE PERIPHERY OF THE CUSHION SPACE FOR THE FULL HEIGHT OF THE WALL STRUCTURE TO CONTAIN SAID CUSHION, AND A SERIES OF STRUTS EXTENDING BETWEEN THE BOTTOM SURFACE OF THE VEHICLE AND THE LOWER EDGE OF THE DIAPHRAGM, OUTBOARD OF THE DIAPHRAGM AND OUTSIDE THE CUSHION SPACE, AND HAVING THEIR LOWER ENDS CONNECTED TO THE LOWER EDGE OF THE DIAPHRAGM TO HOLD THE DIAPHRAGM IN POSITION AGAINST THE CUSHION PRESSURE, EACH STRUT BEING NORMALLY INCLINED DOWNWARDLY AND INWARDS TOWARDS THE CUSHION SPACE AND AT LEAST PART OF EACH STRUT BEING DEFLECTABLE RELATIVE TO THE VEHICLE UPON CONTACT OF THE STRUT WITH THE SURFACE OVER WHICH THE VEHICLE IS OPERATING, THE OUTBOARD SURFACE OF THE DIAPHRAGM BEING EXPOSED TO A PRESSURE LESS THAN THE PRESSURE IN THE CUSHION SPACE, WHEREBY THE DIAPHRAGM NORMALLY ASSUMES AN OUTWARDLY CONVEX CURVED SHAPE AND ROLLS UPWARDLY OVER THE INBOARD FACES OF THE STRUTS WHEN THE STRUTS ARE DEFLECTED INWARDS TOWARDS THE CUSHION SPACE, THE CUSHION PRESSURE EXERTED AGAINST THE ROLLER UP PORTION OF THE DIAPHRAGM ACTING TO DEFLECT TO THE STRUTS OUTWARDLY TOWARDS THEIR NORMAL POSITIONS.