Large Rate Sticks

Rate Stick: ~200 Lbs Bullseye

Generally we use rate sticks for material characterization studies. For example, rate stick experiments can provide an immediate initial characterization of potential terrorist explosives at relatively low costs.

Typically deployed diagnostics include fast framing cameras, high-speed video cameras, arrays of PZT time of arrival pins, Manganin and Carbon stress gauges, and blast over pressure gauges.

In this particular shot series we were studying Bullseye, a common highenergy gun propellant. An asymmetric breakout at the bottom of the tube was successfully recorded several times.

Typically our large rate sticks are constructed from 12 inch PVC. These tubes are loaded with ~180-200 lbs of energetic material, a 12 inch plane wave generator with detonator is mounted on the top of the tube on machine aligned cleats, and the system is detonated in the downward direction.

The asymmetric breakout shown here has not yet been sufficiently studied, but it is speculated that small perturbations, perhaps caused by small gradients in density that result during pouring of the Bullseye powder, might be interacting with a detonation front that is close to neutral stability.

Large Rate Sticks (pdf)