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PROGRAM 10
Project 10.1 = Fireball Hydrodynamics - J. H. Mullaney - LASL
10.2 = Time of Arrival
The object of Program 10.1 is the consideration of fluid dynamics of the
fireball, for the purpose of estimating the yield of an explosion. This program
does no experimental work of its own but relies on Program 15.1, Fireball Photography, by EG&G, for its input data.
These input data are reduced through some
scheme such as the analytic solution or Mach number scaling to give approximate
yield. These methods are both somewhat similiar to the Phi to the 5th scaling
method used by EG&G,
Before Operation REDWING starts, Program 10.1 hopes to have finished, with
the help of the Theoretical Division of this laboratory, a series of calculations
done on the automatic computing machines. These calculations will attempt to
describe the progress of a shock wave thru air starting at a time somewhat earlier
than that used in ISM problem “M" which was done in this laboratory about 10 years
ago.
This new series of calculations will be done usingas realistic an equation
of state of air as we can find and the series will cover a small range of
densities of air. We hope to pick up whatever small departures exist from a simple
atmospheric pressure and density scaling. The calculations should provide one
other basis for scaling at least slightlydifferent from those currently in use.
Some of the shots of this operation are rather low yield devices with
relatively large associated masses, large shields, powder caps amd so on. in the
past, shots with low yield to mass ratio have caused some trouble. Our data
reduction interpretation procedures give yield determinations that are in good
agreement with those given by radiochemistry for high yield devices, but when
these same methods are used in a simple-minded fashion on low yield to mass
devices the energy release figures are much higher than those given by radiochemistry. Program 10 again with the help of the Theoretical Division is trying
to put mass effect work done in this laboratory some years ago in such form that
it can be used in the field.
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The yield of the bomb can be estimated also from time of arrival of the shock
Using hand-held stop watches, the interval between the flash and arrival of
the shock wave can be measured, and then, through use of problem "M" listing, or
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