D.C. The ULDB is approximately 500 feet tall and consists of 20 acres of a special polyethylene composite material and 20 miles of seams.to overall annual temperatures. At launch it is partially inflated with helium with the balloon expanding as it rises. The material used was developed specifically for this project and is twice as strong as materials used in the past. The longitudinal tendons are braided rope cords and run from the top of the balloon to the bottom to handle the pressure load. They are made out of zylon, the strongest and lightest fiber known to man.
Footage includes preparation and launch of the nearly half-sized prototype.
The new material must withstand environmentalstresses the balloon will encounter at 115,000 feet for 100 days. These stresses include temperature variations, pressure, and ultraviolet radiation. Normal balloons are much smaller, vary in altitude by several thousands of feet, can only stay afloat for short periods of time, and carry much smaller payloads. This is NOT a finished production but does contain some narration.