http://www.popsci.com/popsci/aviation/article/0,12543,473272-1,00.htmlI\'m not going to try and explain this, nor am I going to pull out all of the cool quotes, but damn. This is pretty cool.
"The concept behind the PDE is deceptively simple. In short, there are two kinds of combustion: the old, familiar, slow kind of burning, called deflagration, and another, much more energetic process called detonation, which is a different animal entirely. Imagine a tube, closed at one end and filled with a mixture of fuel and air. A spark ignites the fuel at the closed end, and a combustion reaction propagates down the tube. In deflagration—even in "fast flame" situations ordinarily called explosions—that reaction moves at tens of meters per second at most. But in detonation, a supersonic shock wave slams down the tube at thousands of meters per second, close to Mach 5, compressing and igniting fuel and air almost instantaneously in a narrow, high-pressure, heat-release zone. "
