A balloon system includes a balloon having a balloon membrane extending between an upper apex and a lower apex opening. The lower apex opening extends through the balloon membrane at a balloon lip. A ballonet is 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 and an upper ballonet panel having an upper perimeter edge. The upper and lower ballonet panels are coupled along the respective upper and lower perimeter edges. A lower apex fitting couples the ballonet with the balloon at the balloon lip of the lower apex opening.