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SHOCK-WAVE PARAMETERS MEASURED OFF THE ENDS AND PERPENDICULAR BISECTOR 
OF LINE CHARGES 25 FT LONG CONTAINING 50 LB OF FLEXED TNT 
I. INTRODUCTION 
1. Nature of Problem 
A great many measurements of the primary shock wave have been made 
for large charges, usually of symmetrical cylindrical shape (i.e., 
height = dianoter}, although spherical charges have been used in certain 
experiments.1,2) To develop a better understanding of the fundamental 
nature of shock waves as they are affected by charge shape, a number 
of different charge shapes must be used. Such studies have been 
carried out on small charges photographically3) and with piezoelectric 
and diaphragm gauges’) at UERL, on Cordtex (similar to primacord) by 
the Britjsh,5) and have been investigated theoretically by Rice and 
Grinnel. 97) Owing to instrumental and experimental limitations, 
the Cordtex experiments did not yield as much information as was desired. 
To obtain more information, a number of measurements of the shock wave 
have been carried out at UERL with gauges on the extension of the 
longitudinal axis and also on the perpendicular bisector of 50 1b 
"flexed" TNT charges, 25 ft long. The results so obtained are in agree- 
ment with calculations made by considering the relative velocities of 
the detonation wave through the explosive and of the shock wave through 
water. They cannot be compared directly, however, with the calculations 
of Rice,6,7) owing to his assumption of infinite detonation velocity and 
charge length. 
II. EXPERIMENTAL ARRANGEMENTS 
2. Charges 
The charges used in these tests were US Navy Mark 8 demolition 
charges, which contained 50 lb of "flexed" INT in a 2 in. inside 
diameter rubber hose 25 ft long. ("Flexed" TNT is prepared by 
pouring the molten INT into the rubber hose, which is then subjected 
to continued flexing until the INT has solidified in the form of 
densely packed crystals.) As will be noted in Fig. 1 a tetryl booster 
was cast into each end of the charge; the charges were detonated 
statically by means of a US Army Engineer's Special Electric Detonator 
placed in one or both of the ends of the charge, as desired. 
3. Instrumentation 
Four pairs of piezoelectric gauges were arranged at four distances 
from the charge, on a horizontal line 40 ft below and parallel to the 
water surface. These gauges were all forward of the charge as it was 
towed through the water. Two light gauge blocks, each mounting two 
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