The Roswell Report: Fact vs. Fiction in the New Mexico Desert

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will cause the balloon to descend. Third, as a consequence of the previous limitation, the maximum floating period of a balloon with this control system is 24 hours, achieved when launching is at sunset.

When any or all of the above objections prohibit the use of this simple control system, more complex ballast dropping devices may be used. Figure 9 shows in schematic form the servo or demand type control which has been used to maintain balloons at a constant pressure level, with high ballast efficiency and without harmful sunset effects. Figure 10 is the ballast reservoir assembly which is used with this type control. A more detailed discussion of this servo-control is given in Technical Report Number 2 of the Balloon Project, New York University.

## C. Flight Termination Gear

When a balloon loses buoyancy by the loss of lifting gas, it sinks slowly to earth. To prevent the balloon from remaining in airplane traffic lanes for a long period of time, a flight termination device is added to the equipment train. This device, shown in Figure 11, consists of a pressure-actuated switch and rigging to tear a large hole in the balloon when it descends to some predetermined height. A pressure pen is held above its commutator by a short shelf (see Figure 12). After passing an altitude corresponding to the end of the shelf, the pen falls onto the commutator. Upon subsequent descent to 20,000 feet, it closes an electrical circuit. When this circuit is closed, a squib is detonated in an aluminum "cannon" (see Figures 13 and 14) driving a pellet through the main load line. As the line is severed, the weight of the load is suddenly taken by a rip line which extends nearly taut (about 2 feet slack) up the side of the balloon to a point about 10 feet below the balloon crown. At this point, two small holes about 18" apart have been made, and the rip line is passed from the outside into the balloon through the top hole, then down the inside and out the bottom hole. Both holes are securely taped with acetate fiber tape. About 6 inches of slack line is left inside the balloon. When the main line is cut, a large hole is made in the fabric by this rip line as it pulls out of the balloon. After the instruments have fallen about 10 feet and the rip is made, they are caught up by a snub line and the load is again taken to the load ring. The ruptured balloon then acts as a parachute for the load, descending at about 1000 to 1500 feet per minute.