1057 
PRESSURES PRODUCED BY THE UNDERWATER 
EXPLOSION OF LINE CHARGES 
G. Charlesworth 
November 1943 
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Summat'y 
Pressure=time curves have been obtained with piezo-electric gauges at points near to line charges 
consisting of lengths of Cordtex detonated under water. Measurements on the perpendicular bisectors 
of 30, 14 and 5 feet lengths of charge showed that the peak pressure was not appreciably affected by 
the length of the charge but. that the impulse decreased with length of charge. Measurements were also - 
made at points on the axes of 5 feet lengths of Cordtex with detonation towards and away from the gauges. 
At the same distance from the charge the maximum pressures were greatest at points on the perpendicular 
bisector and least on the axis in the direction of detonation of the charge. The rate of decay of 
pressure behind the wave front was less on the axis than at right angles to it, It is suggested that 
the enhanced peak pressure on the axis. when detonation took place away from the gauge may have been 
partly due to the added effect of the detonator. The impulses on the axis were independent of the 
direction of detonation and about half those on the perpendicular bisector of the charge. This 
difference may have beén partly due to the effect of the negative surface reflection reducing the 
imputses more at points on the axis than at right angles to it. 
Introduction. 
The object of the tests was to determine the form and magnitude of the pressures produced by 
underwater explosion of line charges. 
Experimental. 
Pressure measurement:— Pressures were measured by piezo-electric gauges recording 
photographically by means of cathode-ray oscil lographs. 
Charges:— The charges used consisted of varicus lengths of Cordtex containing about 3.3 gm. 
of P,E,T.N./ft. The charges were stretched in a straight line parallel to the water surface, 
ite:- The tests were made in a concrete tank containing about 36,000 gallons of water, 
the depth of water being about 9 feet 6 inches. The charges and gauges were all about 3 feet 
6 inches deep. 
Arrangement of Tests. 
Two sets of tests were made:= 
(a) Pressures were measured at points on the perpendicular bisector of the line charge 
for charge lensths of 30 fer t, 14 feet and 5 feet. 
(b) Measurements were made along the axis of the charge, the charge being detonated towards 
the gauges in one case and away from them in the other, 
The arrangements are shown diaurammetically In-Figure 4. 
ResultS seves 
