Atmospheric balloon system

A balloon having a balloon membrane extending between an upper apex and a lower apex opening, the lower apex opening extending through the balloon membrane at a balloon lip;

• a ballonet within the balloon, the ballonet is coupled with the balloon membrane at the lower apex opening, the ballonet includes:
• a lower ballonet panel having a lower perimeter edge and a ballonet orifice extending through the lower ballonet panel at a ballonet lip, the ballonet lip includes a flat ring extending around the ballonet orifice,
• an upper ballonet panel having an upper perimeter edge,
• wherein the upper and lower ballonet panels are coupled along the respective upper and lower perimeter edges;
• and
• a lower apex fitting coupling the ballonet lip with the balloon at the balloon lip of the lower apex opening, the lower apex fitting includes first and second clamping rings, and the flat ring of the ballonet lip is coupled in surface to surface contact with the first and second clamping rings.

A method for assembling an atmospheric balloon system comprising:

• positioning an upper ballonet panel over a lower ballonet panel;
• joining the upper and lower ballonet panels along respective upper and lower perimeter edges;
• clamping a ballonet lip of the lower ballonet panel in a lower apex fitting, clamping including engaging a flat ring of the ballonet lip in continuous surface to surface contact around the lower apex fitting with first and second clamping rings of the lower apex fitting;
• and
• installing the ballonet within a balloon, installing the ballonet includes:
• feeding the ballonet through a lower apex opening of the balloon, and
• coupling the lower apex fitting with a balloon lip of the balloon at the lower apex opening.