Appraisal of UTIAS implosion-driven hypervelocity launchers and shock tubes

Abstract

A critical appraisal is made of the design, research, development, and operation of the novel UTIAS implosion-driven hypervelocity launchers and shock tubes. Explosively driven (PbN 6-leadazide, PETN-pentaerythritetetranitrate) implosions in detonating stoichiometric hydrogen-oxygen mixtures have been successfully developed as drivers for hypervelocity launchers and shock tubes in a safe and reusable facility. Intense loadings at very high calculated pressures (almost megabar range), densities (g/cm 3) and temperatures (thousands °K), at the implosion centre, cause severe problems with projectile integrity. Misalignment of the focal point can occur and add to the difficulty in using small calibre (6–8 mm dia.) projectiles. In addition, the extreme driving conditions cause barrel expansion, erosion, and possible gas leakage from the base to the head of the projectile which cut the predicted muzzle velocities to half or a third of the lossless calculated values. However, in the case of a shock-tube operation these difficulties are minimized or eliminated and the possibilities of approaching Jovian re-entry velocities are encouraging. In a recent run using about 100 g of explosive PETN and 400 psi 2H 2 + O 2 a shock Mach number M s ≈ 60 was obtained in air at an initial pressure of 1 torr in a 1.0-in.-dia. shock-tube channel. In addition, the use of focused, explosive-driven implosion waves may have many other physical and technological applications.