Experimental Measurement of TNT Equivalency For Contact Charges

The ability to compare explosives is fundamental. Numerous methods are used and while 10 simple conversion factors are often used, the use of TNT Equivalency (TNTe) is not a 11 simple subject as explosives exhibit very different equivalencies depending on whether the 12 pressure or impulse are being considered as well as other conditions. The scaled distance has 13 been found to have a significant effect on the TNTe but due to the difficulty of taking 14 measurements at very close ranges, no TNTe have been quoted for charges in direct contact 15 (Z=0). This paper describes the use of a ballistic pendulum to measure the impulse from 16 contact charges and presents some surprising results that require a two-stage propulsion, as 17 originally described by Backofen, to be explained.