From: gt4458c@prism.gatech.edu (John Stephens Cronin)
Newsgroups: rec.guns
Subject: Re: explosives question
Date: 13 Nov 92 18:01:27 GMT
Article-I.D.: hydra.74729
Organization: Common Container Liberation Front


In article <--fqrs+@dixie.com> jgd@dixie.com (John De Armond) writes:
#gt4458c@prism.gatech.edu (John Stephens Cronin) writes:
#
###2) Same question, but for a large building complex (about 4 or 5 city blocks
###of large buildings).
###
##Definitely going to take a small nuke to do this, no question about it.
##A back pack or tactical artillery nuke ought to be able to do it (ie even
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
##one kiloton might be enough).
              ^^^^^
#Unfortunately this kind of gross overestimation of the capabilities of
#nukes has resulted in the kind of irrational fear commonly seen 
#in years past.
#
Agreed.  I have had people seriously tell me that 5 or 6 big nukes could
destroy the state of Georgia.  It sure as hell would take a LOT more than
that.  I was in the army in Germany when the wall was still up, and one
of the scenarios considered and practiced (as much as possible, obviously)
was one in which nukes had been used.  We were trained to fight on and had
to calculate (by time difference between flash and shock wave) our distance
from the blast, whether we were downwind and due for fallout, etc.  So
I am not one of those who believes that a nuke or two will destroy the
world, although I certainly don't want to be anywhere near one that is
set off.

#Structural damage outside the radius of the actual fireball
#(which might extend a few dozens of yards for a 1 kt device) is done
#primarily by blast overpressure.  Radiant heat does, of course,
#cause fires and kills humans but any structural damage is delayed and
#best classified as collateral to the main blast.  Some figures for
#the destruction of various types of construction:
#
#Frame house							0.5-1 psi
#Typical commercial construction		3 psi
#Reenforced concrete construction	>5 psi.
#
##From my handy-dandy gen-u-wine government issued atomic bomb blast
#computer, a 1 kt device will produce the following overpressure 
#contours for a surface burst:

Do you have a program that computes this stuff?  If so, I would be
interested in obtaining it, if that is possible.  I hate math (why I
switched from engineering to computer science) but I don't mind letting
a computer do it for me.

#	Maximum Dynamic Pressure           radius
#	1 psi                              0.24 mile
#	3 psi                              0.17 mile
#	5 psi                              0.14 mile
#
#This is for flat, unobstructed terrain.  For typical urban terrain,
#large structural damage (buildings down) would likely be limited to a block 
#or two.  
D
OK.  I admit a one kiloton blast might be insufficient.  However, it was
just a very rough estimate.  Still, backpack nukes and tactical nukes,
which was the main thrust of the argument, often have yields in the 5 to
20 kiloton range.  For comparison, the Hiroshima and Nagasaki blasts were
in the 20 kiloton range, and this certainly seemed to destroy more than
4 or 5 blocks.  Admittedly, they were also airbursts, which have the
advantage of being less dependent on whether the terrain is open or
cluttered by large buildings.  In the final analysis, however, I think
a backpack nuke should do the job.

#A one kt device would make a large bang but it would NOT destroy even a 
#significant part of a large city.

Well, it depends on whether a part you consider significant was near
ground zero, doesn't it?  :)  In any event, it could be argued that the
original post was not asking about destroying a significant part of a
large city, just 4 or 5 blocks of it.  In this context, the difference
between 1 or 2 blocks and 4 or 5 blocks is not that significant, although
I will admit your level of research and expertise is higher than mine.
Of course, properly place, only a few tons of TNT or C4 or some other
high explosive would be actually needed, if you had the time and expertise
to distribute them for maximum effect.

-- 
John Cronin	Internet: gt4458c@prism.gatech.edu	Phone: (404) 876-1419
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Live each day as if it's your last.  One day you'll be right.  -- me
Lighten up, you're gonna die whether you have fun or not.      -- me again