Patent ID: 8777156

Claim:
A vehicle comprising: a gas impermeable body; a heavier than air gas having a composition that is different from air; a flexible barrier comprising a lightweight nylon or polyester scrim attached internally to the body and separating the body into a lift compartment configured to hold a lighter than air gas and a ballast compartment configured to hold the heavier than air gas; and a one-way discharge valve positioned within the ballast compartment and configured to open and to permit passage of the heavier than air gas from the ballast compartment to an exterior of the body at a predetermined threshold based on a pressure differential between an interior of the body and the exterior of the body caused by the ascent of the vehicle, wherein, upon release, through the one-way discharge valve, of the heavier than air gas from the ballast compartment, the flexible barrier moves, allowing the volume of the lift compartment to increase as the volume of the ballast compartment decreases.