Advance Detonation in a Tubular Charge of Explosive

Abstract

A GENERAL study of the effects of a void within an unconfined solid explosive on its detonative properties was made in these laboratories in 1941 and later; some new observations were made. One effect, as shown by rotating-mirror camera records, is that the velocity of detonation of a tubular charge is higher than normal ; for example, with a cylindrical charge of cast 40 : 60-tetryl/T.N.T. (density 1.62), 1¼ in. in external diameter, with an open axial cavity, 14 in. long and ¼ in. in diameter, the steady velocity of detonation in the tube wall is 7,410 m./sec., as compared with the normal rate of 7,125 m./sec. in a solid cylinder of the same diameter¹. Inside the cavity in these conditions a luminous phenomenon (recorded by the camera because of the translucency of the explosive) travels at a sensibly constant speed of about 12,500 m./sec., and thus out-distances the detonation wave in the wall. In the open, beyond the end of the tube, the effect is recorded as an intense flame having temporarily a still higher speed.