Flight 97: Released from Alamogordo, New Mexico, 0856 MST, September 10, 1948 Recovered at Duncan, Oklahoma
On this flight a .001", 20-foot polyethylene balloon was used to test a new type of ballast control. In this system, ballast flow was excited at any altitude if the balloon descended at a rate equal to or greater than 1 milli bar in five minutes.
The buoyancy record and the Olland-cycle pressure data obtained from this flight show a disagreement of about 10,000 feet (Figure 45). No explanation has been provided for this difference and the following evidence has been considered. The predicted floating level was about 45,000 feet, in agreement with the Olland-cycle radiosonde data. On the other hand, the balloon rose extremely slowly and may have taken in air to dilute the lifting gas. In this event, the floating level might easily have been reduced by 10,000 feet.
Figure 45
Once at the floating level, however, the balloon was maintained within 1000 feet (or 1200 feet) of a constant level for over four hours. This indicated that the control system was in operation since previous flights (88 and 93) at this altitude descended after about two hours of flight without ballast.