Ribbed cushion bounding walls for ground effect machines

Claim 1

A VEHICLE FOR TRAVELLING OVER A SURFACE AND WHICH IS SUPPORTED ABOVE THAT SURFACE, AT LEAST IN PART, BY A CUSHION OF PRESSURISED GAS FORMED BENEATH THE VEHICLE, INCLUDING A WALL STRUCTURE CONTAINING THE CUSHION FOR AT LEAST PART OF ITS PERIPHERY COMPRISING A PLURALITY OF RIB MEMBERS DEPENDING DOWNWARDLY BELOW THE LOWER PART OF THE VEHICLE AND SPACED APART IN DATUM POSITIONS TO FORM A SERIES EXTENDING FOR THE SAID PART OF SAID PERIPHERY OF THE CUSHION, THE RIB MEMBERS BEING DEFLECTABLE IN DIRECTIONS PARALLEL TO SAID PERIPHERY BUT HAVING, COLLECTIVELY, A STIFFNESS IN A DIRECTION NORMAL TO THE SAID PERIPHERY SUFFICIENT TO PREVENT DEFLECTION IN SIDEWAYS DIRECTIONS AND TO SUSTAIN THE PRESSURE OF THE CUSHION WHEN FORMED, CUSHION-CONTAINING MEANS EXTENDING BETWEEN THE RIB MEMBERS TO ASSIST IN CONTAINING THE CUSHION WHILE PERMITTING VARIATION IN THE SPACED APART RELATIONSHIP OF THE RIB MEMBERS, AND STABILISING MEANS ATTACHED TO AND EXTENDING BETWEEN ADJACENT RIB MEMBERS AND PROVIDING A SUPPORT TENDING TO RETURN THE RIB MEMBERS TO THEIR DATUM POSITIONS.