substantially smaller tubes 26 the tubes 26 comprise end ring tubes 28 disposed at the respective front and rear end of the tube 2 intermediate ring tubes 30 are disposed intermediate the front and rear end of the tube 2 longitudinal tubes 32 connect the end ring tubes 28 and the intermediate ring tubes 30 into one communicating network of tubes the network of tubes 26 provides a supporting framework when inflated to the tube 2 although a specific arrangement of small tubes 28 30 and 32 is disclosed other arrangements may be used that would provide the same function of supporting the tube 2 in the deployed form the ring tubes 28 and 30 and the longitudinal tubes 32 have a cross sectional area substantially smaller than the cross sectional area of the main tube 2 the outlet 14 of the valve assembly 7 communicates with the network of tubes 26 preferably via one of the intermediate ring tubes 30 as best shown in fig6 in this manner the compressed gas fills up the network of tubes 26 relatively quickly with the gas filling up the ring tube which functions as a header connecting the longitudinal tubes 32 and the other ring tubes to facilitate the flow of the gas advantageously the gas cylinder 6 only needs sufficient capacity to fill up the network of tubes 26 which is much smaller than the volume required to fill up.