a
Standard water calorimetry aecnous were sufficiently accurace (= 5 pesccui)
for the larger therzal radiation instrm=ments, but chis aethod was ruled our for
the X-ray instrioents because of the need for greater accuracy ia Chese oeasure~
ments.
The heat capacity of these calorimeters was measured to within 3 percent
by sizulraneously eaploying the eabedded sensing elements as electrical beaters
and chermumeters, recording teaperature rise versus tine as a function of enerzy
input.
Upon reaching steady-state conditions, the time rate of energy input
equals the product of beat capacity times the time rate of tesperature increase.
actually, beat losses became significant about 2 minutes after reaching the
steady-state condirions, so that walues recorded after this time wre cever
used for deriving heat capacity.
The two upper instrument rockets carried X-ray and thernsl transducers of
the types shown in Figs. 2.16 and 2.17 with the exception of a change in X-ray
filters oa the lower rucket, as previously noted in Section 2.1.2, due to lower
predicted X-ray intensities at this position.
Since these instruments were mounted in the carrier aidsections and the
carriers were spin stabilized, a problem was iamediately evident.
Examinatioa
cf the planned positions of these two rockets at burst time reveals the difficulties wre clearly.
In the case of the uppermost carrier (Station TK-252, ,
Fig. 1.1), the transducers had to face radially outward from the midsection aod
see equally well around the midsection circumference.
Six dual X-ray traas-
ducers and eight thermal radiation calorimeters accomplished this satisfactorily,
as discussed previously in Section 2.1.1.
Since a limited oumber of teleneter-
ing subchannels were available, a total of 20 calorimeter outputs had to be
monitored by three subchannels.
This was accocplished by eaploying readout cir-
cuits of the type shown in Fig. 2.18.
This circuit consisted of a sinple
Wheatstone bridge which monitored the temperature of six caloriseters and
supplied four voltage calibration steps each second by subcoceatation; eight
calorineters were sonitored by the same circuit by sacrificing tso of the calibration steps.
The fixed bridge resistors and calibration resistors used were
potaoiy insensitive to temperature.
It was necessary to have the “read” posi-
tion separated by ground positions, as shown in the illustration, to prevent
overdriving the subchannel during the "make-before-breax” intervals of the subcommutating cycle.
Instriments in the second roczet (Station TK-Z209, Fig. 1.1) bad to face
upward along the rocket axis and had to be located about 8 isches outside the