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

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its bursting diameter, the gear strikes the ground, or corrective action is taken. Even if the extremely critical balance is initially achieved, there will be unbalance occasioned by (1) bursting of balloons due to deterioration in the sunlight, (2) diffusion of lifting gas from the balloons, (3) loss or gain of buoyancy when temperature inside the balloon changes with respect to the ambient air temperature. This will result initially from radiative differences, and after an amount of difference (superheat) has been established, changes in ventilation will cause changes in buoyancy.

Two methods of attaching the payload to the clusters of rubber balloons were tried. In the first of these (Figure 3) a long load line was used, and short lines led from it to the individual balloons. The length of such arrays was as much as 800 feet, and this size made them difficult to launch. The single load ring array, seen in Figure 4, proved to be much easier to handle and is recommended for cluster launchings. During ascent each of the balloons in such an array ride separated from each other and no rubbing or chafing has been observed.

The controls which were associated with this balloon system were crude and, in general, ineffective. They included (1) cutting off balloons as the buoyancy became excessive and a preset altitude extreme was passed, and (2) releasing part of the load in the form of solid or liquid ballast whenever descent occurred. The sensitivity of these elastic balloons makes it difficult to control their altitude with any system of controls, and as controls were developed it was found more practical to change from freely expanding balloons to non-extensible cells not made of neoprene. The tendency of neoprene to decay within a few hours when exposed to sunlight was the most cogent argument against doing more work on altitude controls to be used with such a system.

## B. Plastic Balloons

The next attempts to control the altitude of a balloon vehicle were made using non-extensible plastic cells, with an open bottom to prevent rupture when expansion of the lifting gas is excessive. With a fixed maximum volume, such a system has inherent vertical instability in only one direction. When full, there is a pressure altitude above which a given load will not be carried. The instability of such a system is found only when an unbalanced downward force exists. The development of controls and films for balloon material proceeded concurrently, but the choice of a non-extensible plastic film was made before the system of control was perfected.

The properties which were given most consideration in the selection of fabric include (1) availability and cost, (2) ease of fabrication and (3) satisfactory chemical and physical properties. Pri-