Theory of Jet Formation by Charges with Lined Conical Cavities

An article by Birkhoff, MacDougall, Pugh, and Taylor (see reference 1) presented hydrodynamic theories of jet formation and target penetration by explosives with lined conical cavities. However, it was unable to explain satisfactorily why the jets produced are several times as long and, therefore, several times as effective as the steady-state theory predicts. It is shown here that these difficulties are overcome by assuming a variable instead of a constant collapse velocity for the walls of the conical liner. The variability in the collapse velocity produces a surprisingly large change in the process of jet formation.