A desoription of the use of this barograph is given in Part II,
"Opera tiona," of this report.
B. Temperature Measuremen!
To interpret some of the observed balloon behavior, a knowledge
of the temperature of the gas and the outside air temFerature was
required. The evaluation of "superheat" effects was accomplished
pri.me.rily by exposing a conventional radiosonde thermistor inside
the balloon with a control thermistor measuring the free-air tempera-
ture. Similarly, a thermistor was someti~es installed inside the
battery-pack housing to measure the temperature of the batteries.
While this system was in use it was general practice to use the
standard government service thermistors ML 376/.Aid (brown) and
ML 395/W.Q-1 (white). The white elements 1':ere needed' when the ex-
ternal temperature was measured, since no adequate protection from
the sun was available. Also, at floating level there is no venti-
lation to be had since the balloon is stationary with respect to
the air. ·
The resistance of the thermistors was switched into the grid.cireuit
of the blocking oscillator of the AM-1 transmitter, and by compari-
son with pre-flight ealibrations the audio frequency transmitted
could be interpreted in terms of temperature. To record the signal
after it was received, a fast-speed Brush Co. Oscillograph Model BL212
is used. (Due to the frequency response of the Brush recording
system, the circuit was arranged to give lower frequencies than a
standard radiosonde for the same temperature range.) A sample cali-
bration chart is shown in_Figure 34.
+60
+40
Q +20
cio
•0
J.. 0
e
•.....
-20
-40
-60
20
If,
}
Freauencv-· c~• J40 60 8/ 100
~
/
v/
Figure 34. Sa:nple calibration chart for
temperature measurements.
-74-