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

capsule and linkage is of conventional design but in place of the commutator bar, a motor driven helix is employed. This system permits the determination of

FIG. 4. Minimum pressure switch (mercurial).

pressure data without knowledge of the history of contact sequence or of the ascent or descent of the balloon, as is required in the conventional radiosonde.

## 5. Tracking of the balloon

The balloons that have been flown by the writers usually have been tracked by theodolites. Airplanes have also been used, to extend the observations. These two methods require the balloon to be visible and not obscured by cloud cover. When available, ground radar has been used in tracking the balloons, with good results.

A series of SCR 658 radio direction-finders is also used, arranged in a net along the expected trajectory of the balloon. In addition, aircraft equipped with inverted search radar have been employed to extend the tracking net.

## 6. Flight results

While the characteristics of various plastics were being investigated, four preliminary flights were made with clusters of ordinary meteorological balloons, from 16 to 26 in number, to which two to four towing balloons were attached. The towing balloons were cut free by a baroswitch at a predetermined altitude. The remainder of the balloons were inflated so that they exactly balanced the load hung from the cluster. To offset diffusion, sand was dropped from an arrangement of tubes, 9 to 16 in number, each containing about 200 to 1500 grams of sand ballast. This ballast was dropped by a baroswitch mechanism on descent

only. Some of these flights were relatively successful as a beginning method but the dropping of discrete quantities of sand caused too great fluctuation of altitude and therefore was abandoned later. The first successful flight stayed at 51,000 ft, plus or minus 100 ft, for 38 minutes; another remained between 30,000 and 40,000 ft for 147 minutes. The latter shows the same characteristic time-altitude curve as the cosmicray clusters, although its altitude control is superior. It is not believed that much improved altitude control can be obtained, utilizing ordinary meteorological balloons. Flight termination was usually due to deterioration of the balloon caused by the sun.

In the first flight utilizing plastic balloons, a cluster of ten seven-foot diameter balloons $ ^{6} $ was used. The load on the cluster was 16.5 kilograms. An altitude control was used. Unfortunately, the maximum altitude reached was not as high as the predetermined altitude which was selected to seal the diaphragm of the automatic ballast valve. As a result, the cluster rose to ceiling and stayed at this altitude for a short while. Diffusion and leakage of helium produced a loss of lift at the rate of 125 feet per minute.

The next flight was made with a single polyethylene balloon, 15 ft in diameter. To insure sealing-off, the ballast-release diaphragm was set to operate at an altitude of 12,000 ft, considerably below the calculated ceiling of the balloon. After a dawn release the balloon continued to ascend to 15,100 ft where it leveled off, then slowly descended to 9000 ft due to diffusion losses. At this altitude the ballast release began to operate and thereafter the balloon maintained its altitude within $ \pm 1300 $ ft for a period of $ 4\frac{1}{2} $ hours before the radio signal was lost. However, in the first two hours of this period, before the convection currents

FIG. 5. Olland-cycle pressure modulator.