tained on all six shots.
PROGRAM i: BLAST AND SHOCK
MEASUREMENTS
Non-ideal wave forms op-
tained indicated that water does not constitute a per-
Project 1.la, 1.1b, and 1.1d “Blast Pressures and
Shock Phenomena Measurements by Photography”
(WT-902), Naval Ordnance Laboratory; C. J. Aronson,
fectly reflecting surface, as had sometimes been
assumed. Shot 3 was detonated in the rain and showed the effects there in low pressures and rounded
wave forms. It was concluded that peak pressures
generally correspond to about 1.6W instead of 2W
free air when the hydrodynamic firebali yields, using
2W theory, are the referenceyicids.
Project Officer.
The objectives of these projects were lo (1) determine the peak shock overpressures in air as a function
of distance from ground zero, (2) to obtain information on the furmation, growth, and magnitude of precursors and other visibly observable thermal effects
which may occur, and (3) to measure the motion of
the shock wave on the waters surfice to obtain the
pressure-distance relation.
The smoke-rocket photography and direct-shock
The principal mission was to obtain pressure-time
data in the region greater than 40 psi. A scvondary
photcgraphy results were in general satistactory.
objective was to field~test a newly developed self-
Some data were lost due to photographic difficulties
and the presence of cloud cover at the time of detonation for several shots. The project participated on
all shots, but no film was usable from Shot 3 because
of the low yield of the device. Pressure-distance
data vertically above the shot were obtained only on
Shot 2. The uncertainty of the measured date was
such that it was not possible to define the effect of a
nonhomogeneous atmosphcre on blast. Measured surface data of both pressure and arrival time appear
self-consistent, as well as comparing favorably with
Jangle and Ivy data. It seems justified to conclude that
cube-root scaling of blast data from events of this
yield range is valid.
No precursors as such were
noted; however, anomalous wave furms were recorded
by the pressure-time gages. aA dense water cloud
following immediately behind the shot on Shots 4 and
5 may explain the anomaly. The aerial photography
was unsuccessful. The extreme range of the aircraft
and the obscuration of the field of view by clouds prevented the project from obtaining any readable film.
Project 1.lc “Base Surge Measurements by Photography” (WT-903), Naval Ordnance Laboratory;
Cc. J. Aronsor., Project Officer.
The objective was to gather photographic data obtained during the operation which could be of value in
the formulation of scaling laws to predict the basesurge effects from surface detonations.
The experiment was almost entirely unsuccessful,
since photography was rendered useless when it was
decided to schedule detonation of the skots before sun-
rise. A minimum effort was maintained throughout
the series, which indicated a possible base surge formation on Shots 1 and 2; however, a detailed study
could not be accomplished.
Project 1.2a “Ground Level Pressures from Sur-
face Bursts” (WT-904), Sandia Corporation; C. D.
Broyles, Project Officer.
This project was directed toward obtaining meas-
urements on blast pressure versus time at ground
level with Wiancko gages. Measurements were ob~
Project 1.26 “Ground Surface Air Pressure versus Distance from High Yield Detonations (WT-905),
Ballistic Research Laboratories; J. J. Meszaros,
Project Officer.
recording pitot gage.
Pressure-time measurements
were made on ali six shots.
Two blast lines were
activated for Shot 3, and pressure measurements
were obtained on both lines.
Extensive dynamic-
pressure measurements were made on Shot 6.
Air-pressure measurements using the self{contained flast-initiated gages were successful.
Overpressure data were obtained up to pressure
levels of 250 psi. Dynamic-pressure measurements
using newly developed self-recording q-gages were
very successful. Measurements were obtaincd aver
a dynamic pressure range of 0.43 to 138 psi. Shot 3
produced anomalous reaults: two blast lines oriented
approximately 180 degrees apart obtained two distinct
pressure-distance relations. The pressures chtained
on the Tare line. cver which rain or fog was evident
during detonation, were as much as 20-percent lower
than the pressures at comparable distances on Uncle
Island.
The validity of the cube-root scaling law to scale
distances for yields as great as 15.0 Mt appears to
have been substantiated. It was concluded that overpressures from a surface burst are the same as
would be obtained from a burst of 1.6 times the yield
in free air.
Project 1.3 “Dynamic Pressure Measurements”
(WT-906), Sandia Corporation; C. D. Broyles, Project Officer.
The objectives were to spot check the theoretical
relationship between dynamic pressure and overpressure in the 10-to-40 pal overpressure range, and to
evaluate a group of gages measuring various blast
parameters.
The single measurement of dynamic preasure obtained on Shot 6 in an overpressure region of 21.5 psi
agreed with that normally associated with the overpressure. The instrument was located such that the
shock had travelled 800 feet over land immediately
before reaching the gage. On Shots 4 and 5, measurements of dynamic pressures by the gage group
- were higher than values calculated from the measured overpressures; the records showed peculiar
106