Tannerite a patented binary solid explosive is intended to be
detonated by a high velocity rifle bullet.
Lesser velocities don't work.
The term you are looking for is "brisance". The "sudden" of what Ben says.
Gen. Julian Hatch, NRA Technical Director for many years, has many
interesting thing described in his book, "Hatchers Notebook".
In chapter 21, "Explosions and Powder Fires" he discusses the
requirement of "brisance" or shattering effect required to initiate
detonations.
Later in that chapter (page 528) he describes "Ignition of Powder by
Rifle Bullets". They did some tests with soldiers shooting
Springfield.30-06 into 150 lbs cannister of smokeless power to see if
they could be ignited. Usually they would be. But they found if
they shot the barrel at the bottom with more than 2 ft of power
above, the whole thing would detonate. Knocked a sitting shooter 100
ft away end over end he said.
Fascinating book, sort of an earlier incarnation of Myth Busters on gun stuff.
Ed Kelleher
att 11:12 AM 08/12/2015, Ben Brockert wrote:
Normally they're set off by the shockwave of the explosive nearby
going off, which is to say that sudden large pressure rises set them
off. A heartily supersonic bullet can make a large sudden pressure
spike, a 300 mph impact not so much.
On Mon, Aug 3, 2015 at 7:02 PM, Dave McMillan <skyefire@xxxxxxxxxxxx> wrote:
>
> The recent PEPCON discussionk, along with a recent MythBusters rerun,
> got me to thinking on this subject. The Mythbusters ep in question is the
> one where they demonstrate that a Hollwood SFX explosive can be set off by a
> high-powered rifle bullet (~1400mph, IIRC), but then tried to set off a
> car-trunk load of the stuff by slamming a truck into it at ~300 mph (using
> the University of New Mexico's rocket sled), and failed. A quick BOTE
> suggests that the truck should have had more than 200x the impact energy of
> the bullet, so I got to thinking: just what are the key factors in play
> here? Total impact energy obviously isn't it. Is it energy *concentration*
> -- joules/unit volume, or even joules/impact area? Or is it the impact
> *velocity*, as relative to the shockwave propagation rate in the explosive?
> Or is this one of those questions where the answer is "it depends"? :)
>