Flight 78: Released from Alamogordo, New Mexico, 2038 MST, July 22, 1948
Not recovered
This flight was the first to be made with (white) thermistors exposed in-
side the .001" polyethylene balloon, inside the battery box and exposed to
the air. The flight was at night and the be.lloon temperature was. colder than
the air temperature by about 50C during the short period of tizr.e that the
temperature valUts were telemetered. The standard SCR-658 receiver and
Friez radiosonde ground station were used to record this data Which was trans-
mitted by a T-69 radiosonde. A New York University AM-1 transmitter was
used to send out pressure data.
An automatic ballast valve, activated by a mercury minimum-pressure swi toh,
was used to control ballast flow but the cold temperature _presumably caused
the mercury to freeze and no ballast flow was 8'l7idenced. (A ballast-metering
siphon was part of the equipment.)
On subsequent flights, the minimum-pressure switch used en electrolite
which can withstand the cold nighttime temperatures of the upper air.
The evidence of the the~.istor in the battery box is very encouraging,
since after four hours of flight the temperature remained above lOOC. This
was the first measurement obtained on the cooling of batterie~ and indicated
that no special cold te~perature batteries were needed if insulation is care-
fully made. The temperature data and the height-ti.'Ile curve of Flight 78 are
shown in Figure ~1.
r ~ FLIGHT 78
40 Released at Alamogordo, N.M.
~~ July 22, 1948- 2038 MST
OLLAND OYOL! DATA
LHII
j~ I "'~' "1----~·~'~ 20
""'
'.. ' -
110
~J -o .., ~- ...~. 0
"'
~ II - -20~
~ " ,.
i 1 ,, - ..\I ... ~\\ Balloon temp.~ --40,, __ .....
10 '' Aort~ _-::.--~-
J '\.':.:::-:;~- --eo .,.,...,.I
I .Go I el I I0100 0100
IJ411-MU
Figure 31
-38-