1085 
SHOCK-WAVE PARAMETERS FROM SPHERICAL TNT CHARGES DETONATED UNDER WATER 
by J. S. Coles, BE. A. Christian, J. P. Slifko, C. R. Niffenegger, and 
lis Ae Rogers, Underwater Explosives Kesearch Laboratory, Woods Hole, 
Massachusetts, 1946. 
ABSTRACT 
The similitude curves for peak pressure, momentum, time constant and 
energy of TNT have been determined from experiments with 12 and 14 inoh 
diameter spherical chargese Data are presented from piezoelectric gauges, 
as well as from UERKL diaphragm, Modugno, ball crusher and momentum mechani- 
cal gauges. Kirkwood's theoretioal curves for TNT peak pressures, momentum 
and time constant have been caloulated and are compared with the experimental 
valuese Peak pressures calculated from ball orusher deformations show good 
agreement with piezoelectric gauge results for pressures below 8000 1b/in-2. 
I. INTRODUCTION 
A series of spherical TNT oharges has been shot at the Underwater 
Explosives Research Laboratory in Woods Hole, Massachusetts, to obtain the 
parameters of the explosive and to compare the results with Kirkwood's 
theoretical caloulations. 
The charges were all fired from the schooner "Reliance" with the 
standard rig used on previous underwater work at this laboratory. The 
oharge and gauges were suspended 40 feet below the surface in at least 
80 feet of water. It was especially desired to obtain records in the 
high pressure region where the theoretical ourve deviates from ,the em- 
pirical straight line on a log-log plot % pressures versus wt S/R (cube 
root of the charge weight in pounds = W-/*, and charge-to-gauge distance 
in feet = KR). In order to obtain pressures over the range of 400 to 
20,000 lb/in.® with the charge weights used, the charge-to-gauge distances 
were varied from 100 to 5 feet, and consequently the range of W 3/R was 
0.036 to 0.86. 
Results were obtained from UERL diaphragm, Modugno, ball orusher, and 
momentum mechanical gauges, and from piezoelectrio gauges Data from these 
gauges are given in Tables A-I, A-II, and i783 of the fe Plots 
have been made of peak pressyre, momentum/W1, og energy/WW 5 and time 
constant (6)/i1/> against Wi/3 72 (Figs. 2-8) and equations determined for 
the best straight line through the experimental points. 
II. CHARGES 
The TNT charges were cast into 14 gauge steel spheres of 12 inch 
and 14 inoh diameters, resulting in average TNT charge weights of 48 
pounds and 76 pounds (average loading density of TNT = 1.42). A 250 gram 
pentolite booster (spherical) was cast into the center of ‘each charge. 
The charges were centrally detonated by U. S. Army Engineer's Special 
Eleotrio Detonators (base charge 13.5 grains of PETN) inserted through a 
tube from the bottom of the charge as oriented for firing. Three eye-pads 
welded fore, aft, and topside of the sphere were used to position the 
charges (filling hole to one side) relative to the gauge lines. Six 
charges were fired, three of each weight. 
