1073 
MEASUREMENT OF THE SHCCK WAVE VELOCITY IN AIR ABOVE 
A WATER SURFACE DUE TO THE DETONATION OF 16-Ib. 
SPHERICAL CHARGES OF T.N.T. 
D._Croney 
Poad Research Laboratory, 
London 
March 1946 
Summary. 
In a previous investigation the shock wave and water surface velocities due to the 
detonation of submerged 4-oz. charges of C,E, were measured by an acetylene jet method. The 
results were used to obtain values for the peak shock pressures in the water surface, and these 
values were compared with theoretical figures deduced from the formula given by Penney and 
Dasgupta. 
It was decided to repeat the work on approximately four times the previous scale using 
16-1b. spherical charges of T.N.T., fired at depths (measured to the charge centre of 8, 16 and 
32 in. This investigation was not completed, but several exploratory charges were fired, The 
present report summarises the results obtained on these charges. 
Some of the 4-oz. experiments have been repeated, the Marley high-speed camera working 
at about 6,000 frames/second being used to photograph the water plume. Water surface velocities 
and Peak shock pressures in the water surface deduced from these records are compared with the 
values previously obtained, 
Introduction. 
Experimental data previously reported(1) was used(2) to obtain values for the water and 
air shock pressures associated with the detonation of submerged 4-oz. charges of C.E. In 
particular, the peak shock pressures in the water surface were compared with theoretical values 
obtained from the formula given by Penney and Dasgupta(3). A discrepancy between the calculated 
and experimental values in the case of the shallowest charges was in part attributed to the 
cylindrical shape of the explosive. 
It was decided to repeat the work on four times the previous scale using 16-1b. spherical 
charges of T.N.T. fired at. depths (measured to the charge centre) of 8, 16 and 32 in. This 
investigation was not completed, but the present note summarises the results obtained on several 
exploratory charges which were fired, 
Some of the 4-oz. experiinents have been repeated, and the Marley high-speed camera 
working at about 6,000 frames/second has been used to photograph the water plume. Water surface 
velocities and peak shock pressures in the water surface deduced from these records are compared 
with the values previously obtained. 
Description of Charges. 
16-1b. charges. 
The 16-1b. charges were 8in. diameter spheres of T.N.T. fitted with radial C.E. primers 
each 2 in. in diameter and 4 in. long. The charges were detonated with the primer axis vertical 
and the detunator uppermost. 
4Y-oz, charges. 
The 4-oz. charges were cylindrical pellets of C.E., 2 ine in diameter and 13 in. Vong» 
Each charge was fired with its principal axis vertical. 
Details eevee 
