Patent ID: 7552893
Filing Date: 2009-06-30
Classification: B64B

Abstract:
1. A method for operating an airship, the method comprising the steps of: providing a non-rigid, non-spherical airship having a weight and an outer envelope defining a hull having a first volume, said airship having a propulsion system and a directional control system, said airship also having a second envelope contained within the first volume and the second envelope having a second volume; and a third envelope contained within the second volume and having a third volume for holding lifting gas; said third envelope being expandable within said second envelope to a maximum predetermined volume, inflating said second envelope with a gas having a density greater than said lifting gas; and partially inflating the third envelope with a mass of said lifting gas, thereby permitting the expansion and contraction of the third envelope within the second envelope as the lifting gas expands and contracts during operation, whilst maintaining said mass of said lifting gas within said third envelope during said expansion and contraction; wherein the volume occupied by the lifting gas is sufficient to balance said weight.