roswell

Flig_ht 74: Released from Alamogordo, New Mexico, 1040 MST, July 19, 1948
Not recovered
This was a test of a single 7-foot balloon made of .001" polyethylene,
carrying a 4-kilogram payload. Onepart of the load was the first model
of an automatic ballast siphon used to detect and telemeter the amount of
ballast being discharged throu~h an auto~tic ballast valve.
The balloon flew at 7000 teet MSL across a heated desert area and into
a motmtain paas whose elevation was about 6000 feet MSL. During the first
two hours its behavior was reported by radio, and the accompanying time-
height curve (Figure 28) shows how the ballast valve operated successfully
1010 - IMO IIOCi 1110 1140 1100 IIIII 1140 1100
Figure 28
to sustain the balloon. During this turbulent flight about 200 grams of
ballast were expendod per hour6 but the pronounc·ed orographic and convective
currents probably necessitated more control than would be required in a
more stable e.tmosphere.
The very usef.ul information about be.llast flow was reported clearly, and
the principle of the auto-siphon was used repeatedly on later flights. Small
variations are seen in the pressure at which the ballast flow began. Since
the balloon was floating below the base of clouds, this represents the changes
of activation pressure which resulted from changes of superheat of the air
entrapped in the aneroid.
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