any
wrote
that in the case of three observations, Nos. 2, 3, and 8, the couples did not return to the initial
sero. They all showed negative voltages. The reason is nct apparent. The possibility of a
cooler environment of ambient air is not plausible. A higher temperature for the mass of
brass and lava surrounding the coid junction, although possible, does not appear likely. Therefore two products (millivoits x time) were taken for each of these three radiometers. First,
the area was measured using as a base the initial zero; this waz assumed to hold. Second, the
line connecting the first zero and the negative voltage was used as a base line (see Fig. $.3).
In Talle 3.2 the latter, the “corrected” zero, values are given first; the second values, in
parentheses are those obtained assuming no change during exposurein the zero between cold
and hot junctions. These alternate choices for zero result in alternate values for the data in
the total-thermal column, the peak-intensity column, and the rise-in-temperature column, and
they are distinguished oy enclosing the “uncorrected rero” talues in parentheses,
It is further to be noted that the blast arrived at Mike canister No. 7 before the radiation
puise had ceased. Apparently the shock injured the telemetering system within the canister.
An estimate of the unrecorded remainder of the radiation pulse was attempted, as shown by
the dashed line in Fig. 3.3. This increment would increase the total energy for No. 7 by about
10 per cent. This augmented value is given in parentheses in Table $3.2. The random output
from the injured telemeiter component is not taken as evidence of an injured thermocouple or
of a zero shifc.
$.2
KING SHOT
3.2.1
Blast-overpressure Data
The basic peak-overpresgure, time, altitude, and slant-range data for King shot are given
in Tables 3.3 and 3.4. Sample oscillograph traces are shown in Fig. 3.4, and the overpressure
ve time curves as scaled from the original records and calibration curves are plotted in Fig.
3.5. The records from canisters Nos. 2, $, and 5 show secondary shocks within 0.5 to 2 sec
following the primary shock. It is very probable that these represent the reflection from the
ground and that these canisters therefore lio within the region of regular reflection.* The
records from the other canisters show a single main peak with only a very small secondary
shock at around 6 sec after the primary shock. This is {ar too late an arrival to be attributed
to ground refiection; hence all canisters except Nog. 2, 3, and 5 are assumed to lie within the
region of Mach reflection.
From the time intervals between direct and reflected shocks at canisters Nos. 2, 3, and 5,
a crude estimate of the path of the triple point can be ubtalned by assuming that thia interval
may be extrapolated linearly to zero with distance along straight linea drawn between the pairs
§-3 and 2-3. The locus shown by the dashed Line in Fig. 2.5 is thus obtained. For comparison
the path of the triple point has algo been plotted as computed from the data derived from ex-
periments with high explosives as summarized in Tha Effects of Impact and Explosion.' in the
compuiations a burzit height of 1500 ft, a yield of 550 Kt, and a blast efficiency of 40 per cent
relative to TNT were assumed.
3.2.2
Thermat-radiation Data
For King shot the information similas to that for Mike shot given in Table 3.2 and Fig. 3.3
are presented in Table 3.5 and Fig. 3.6. The records do not show the anomalies found in Mike
shot, aa already discussed.
*Thi« contradicts a etatement made in 2 preliminary report on Operatioa Ivy, Project 6.11,
which was written before the significance of the secondary shocks shown on the pressure-time
records had been adeauately considered tn order to make the principal data on peak overpressuce available to saterested groups as quickly as possible.
26
RESTRICTED DATA “QB secuciry INFORMATION
®:.
$