A SPHERICAL FOCUSED BLAST DEVICE
JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB
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A spherical explosive device that, by selective multipoint initiation, concentrates its energy in a beam along any of several aiming axes is described. Aiming is accomplished by electronically selecting the proper group of detonators, thereby eliminating the necessity of physically aiming the charge as is required in all other focused blast devices. Once fired, these initiators cause a nearly cylindrical detonation wave, collapsing on the focusing axis, which forces the explosive products out along this axis. Three small 14 lb. C-4 spherical focused blast devices have been built and fired. The explosion products velocity, shock wave velocity and peak pressure along the focusing axis were measured. These blast parameters were compared with similar ones measured for centrally initiated spheres the purpose being to achieve a quantitative measure of the degree of focusing. The comparisons revealed that considerable gains over isotropic blast result from this focusing method. Furthermore the focusing appears to be a far field effect in that the values of peak pressure and the shock velocity are nearly equal to those of the centrally initiated sphere in close but tend to fall off much less rapidly with distance. Another result of interest is that the data obtained from the small, 14 lb., 2 inch diameter, centrally initiated spheres are in very good agreement with similar data scaled from much larger spheres.