The suggestion has been made that an equation of the form
R
=
1
(WE) /3 | f(A.) . (m)
is more satisfactory.* When either form is used for the extrapolation
of TNT data to megaton nuclear explosions, a certain range of uncer.
tainty in R is shown, resulting from reasonable values assumed for the
uncertainty in f(\,) and f(m).
The uncertainty in R shown by the sug.
gebted equation form is smaller than that shown by the equation form
used”in.the main body of this report.
Another and more important benefit adduced for the suggested form
is that the predicted crater radii for megaton explosions have a smalle
spread when soil characteristics are changed.
It is the.opinion of the author that the benefits indicated are
illusory and: that the form used in the main body has a slightly better
basis. The true value of crater radius produced by a megaton explosion
in any mediumother than that existing in the Marshall Islands will re.
main unknown until: such a shot is fired and the resulting crater mea.
sured.
In the meantime, it is felt that caution in stating the expec-
ted values and their. uncertainties is of vastly greater military use
than over-optimism.
* One piece of information which has been put forward as favoring the
suggested form of equation is the result of some cratering experiments
in the Marshall Islands. These, experiments were run under the directia
of Dr. H. Kirk Stephenson, durrently on the staff of the National Scien
Foundation.
Quoting from Memorandum SWPEF 2/924 (354.2) dated 26 Nov.
1954, "1. A series of high explosive shots were fired on Elugelab (Flor
Island, Eniwetok Atoll in the aprtgof 1952.
These shots consisted
of a combination of R-7-HDA(c-2)ReJ«HCA(Tetrytal), primacord, and blast
ing caps piled in a beehive shape on the surface which had been excavated down to the high tide level. A dike was established around the
charge to prevent wave interference but| this proved ineffective. In
addition to seismic shock information, “the erater radii were determined
The crater data obtained from these HE shots:fat the Pacific Proving
Grounds may be used to establish a soil factorfor comparing saturated
coral with Nevada soil. A summary of the data is_as follows:
wW(tons TNT Equivalent)
Scale height to
Coke CQ, )
wi/3
Chater Radius
| Rg
1
5
10
15
20
12.6
0.06
eTs5§5
27.1
31.1
34.2
0.06
0.06
0.06
37.5
45.5
50
21.5
(cont. on page 59 )
R,/wi/3
ft.
re
(lbs) /3
1
-
0.06
32
overall average
Average if first shot omitted
58
2 18
1.49
1.39
1.47
1.47
1.60 .
1.46.