at several] Underwater Sound Transmission Experimental Facilities (USTEF) stations in the Pacific and
at similar research stations {in the Atlantic The
studies were designed to lead to a better understanding
wave forms, indicating that the shock had picked up
water.
For these two shots, the gage group was lo-
cated near the edge of the water
The force plate and density gage seemed to be
suitable for field use, but study was needed on their
response to dust.
of the underwater sound propagation and to determine
the accuracy of device yield figures that might be extracted from the measurements.
Shots 2, 4, 5, and 6 were monitored by detecting
stations located on the California coast and at Bermuda. No clear-cut signals were recorded which
could be attributed to sources at either Bikini or Eniwetok. It was concluded that the positions of the shots,
inside the lagoon and on the atoll rim, precluded the
coupling of energy into the SOFAR channel in the frequency channel to which the instruments were sensi-
“Instrumentation for Projects 1.2a, 1.3, and 1.7”
(WT-907), Sandia Corporation; R. H. Thompson,
project Officer.
The primary objective of this project was to make
support measureinents of pressures, shock winds,
and ground accelerations from large scale detonations
for Projects 1.2a, 1.2, and 1.7. A secondary objective was to field-test several new gages.
tive.
“che primary measurements were made with
Wiancko and Sancia pressure transducers, differential-pressure y-tubes, and accelerometers. Other
instrumentation used included drag q-tubes, forecplate stagnation~presaure gages, density gages, temperature gages, and displacement gages.
Of the records taken on 112 data channeis, 99 gave
complete infurmution; 6 gave information up to arrival of the shock wave; and seven gave no information.
Project 1.6 ‘‘Water Wave Measurements” (WT-910),
Scripps Institution of Oceanography; R. R. Revelle
and John D. Isaacs, Project Officers.
The objective was to study water surface waves
generated within the lagoon by a large-yield surface
detonation. The measurements of wave height were
obtained from underwater gages designed to record
the hydrostatic pressure vibrations produced by the
Preliminary evaluation of new inatrumentation
passing wave. In addition, surveya of inundation
levels on land areas wcre made.
In contrast to the Ivy-Mike results, Castle data indicated that the recorded waves did emanate from the
central region of the detonation. The time of arrival
of the first crest of the direct water wave showed a
indicated that: (1) the density gage needed better
waterproginvg, (2) the force plate operated satisfac-
torily, (3) the temperature gage was still too delicate
for field use, (4) the gage q-tube was easy to cali-
orate but needed waterproofing to protect the canti-
lever f-om custing and to protect the E-coil, and (5)
propagation velocity fitting the relation V = (gh)!/?,
the differential cressure gage was easy to calibrate
but needed wate: proofing.
where h is an average depth of 170 feet assumed for
the Bikini lagoon. Refraction and reflection against
the reef or shoreline can significantly reduce or amplify the destructive capabilities of water waves at
termination. Where focusing effects and the reflectionrefraction potential of the adjacent lagoon topography
Project1.4 “Underwater Pressure Measurements”
Project Officer.
This project was designed to measure the under-
water pressure-time field produced by large-yield
surface bursts. Pressure-time measurements and
oall-crusher-gage measurements were obtained for
was a minimum, the heaviest inundation and potential
damage occurred with the first crest. These results
were obtained uncer particular conditions of geometry,
in a region of relatively shallow depth; such damage
Shots 2, 4, 5, and 6; ball-crusher-gage measure-
ments were obtained for Shot 1.
The gages were lo-
criteria are applicable to conditions that depart only
slightly from those under which the data were obtained.
cated as close ag 6,000 feet from ground zero.
Some difficulty with instrumentation was experienced during the operational phase; as a result, a
Project 1.7 “Ground-Motion Studies on Operations
Ivy and Castle” (WT-9002), Sandia Corporation; W. R.
Perrett, Project Officer.
lesser amount of reliable data were obtained than
uriginally anticipated. The major result of the recorded data indicated that the maximum, or peak,
This project was designed to obtain measurements
underwater pressures are of the same magnitude as
the air-blast peak overpressures at the same range.
of three components of ground acceleration on Shota 3
and Echo. These measurements were to be closer in
to ground zero than those obtained on Ivy-Mike and
it was concluded, therefure, that a nuclear weapon
detonated on the surface of a relatively shallow water
layer, under conditions as experienced on the Castle
hence augment and extend those measu ements pre-
shot, produces underwater pressures which are probably of small military significance.
Project 1.5
“Acoustic Pressure Signals in Water
(SOFAR)” (WT~909), Office cf Naval Research; J. W.
Smith, Project Officer.
The objectives were to make special observations
viously obtained. Unfortunately, the yield of Shot 3
was only about a tenth of that expected and Shot Echo
was cancelled.
As @ result of the low actual yield of Shot 3, set
ranges for the gages were too high, recording a verylow signal amplitude. With such a low signal-to-noise
ratio, the identification of phase arrival, frequencies,
107