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—
the blast wave from large incidence angles. Future laboratory analysis and
shock tube work may resolve some of the records.
Next in priority was} _
Lacrosse, the medium kiloton range,
land-surface burst.
Both electro
and self-recording pressure gages obtained excellent,:correlatable data. Observed was a prccursor-type wave of
limited extent — dying out at the close range of about 45 psi. Direct shock
photography from the Mack tower failed. However, shock phctography of
the rocket trails from cameras on Runit should give pressure-distance data
vertically over the burst and at horizontal range. Dragforce gages of
model shapes recorded good loading data at two ranges in the clean Mach
region. These models will be studied in the shock tube, data from which
will be compared with that obtained on the shot. It is hoped that a correlation can be established to determine criteria for estimating or predicting
drag forces on different targets by laboratory experiments.
(Zuni), a surface burst jn the megaton rang¢,-was instrumented
with self-recording gages to obtain basic blast data on the ground surface
and, with shock photography, tu obtain pressure-distance data in the free
air and along the water surfuce. The blast gages were placed on two lines
from GZ, 180° apart, towards Eniirikku and down the Eninman complex. At
present there seems to be a difference in the pressure-distance curve
plotted for each line.
Further study may reveal a reason for this, or it
may furn out to be no more than normal scatter of the data. The pressuretime records from buth blast lines show distorted wave shapes similar to
those associated with a precursor. Excelent photography of both high- and
low-level rockets should give good data vertically over the burst and at
hor’ zontal range over a water surface.
A study of blast diffraction was
made on a Conercte cubical target, instrumented with flush-mounted gages
on the front and side walls and on the top.
[
(Inca) was instrumented with surface gages to document the
propagatfon of a precursor shock over a vegetated and over a cleared sur-
face. The precursor was observed to be less severe over the vegetated
surface than over the cleared area, showing later arrival times, higher
overpressures, and lower dynamic presgures.
The _——
(Yuma), was instrumented with
self-recording surface gages to obtain basic blast data. Data were recorded
which are expected, upon further analysis, to validate the height-of-burst
curves
C¥ater measurements were made on all ground-surface shots. Meceasurements consisted of acrial photography to obtain crater diameter by
means of stereoptic analysis and lead-line sounding surveys for depth profile.
Preliminary results give crater size as follows:
430 ft, depth 45 ft; (2)[~
(1) ~
_
diameter
aianetes 2410 ft, depth about 106 ft; and
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nt